Water Disinfectants Green Facts
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Water Disinfectants Green Facts as PDF for free.
More details
- Words: 6,817
- Pages: 27
Questions on Water Disinfectants
Home > Studies > Water Disinfectants
Scientific Facts on
Water Disinfectants & disinfectant by-products
Source document: IPCS (2000) Summary & Details: GreenFacts (2004)
More
Questions and Answers presented in 3 levels of increasing detail.
Questions on Water Disinfectants
Context - To protect drinking water against germs and fight disease transmitted through water, disinfectants such as chlorine, chloramines, ozone and chlorine dioxide are used. These disinfectants can react with natural material in the water to form certain unwanted by-products, which raise health concerns.
1. What disinfectants and by-products are we talking about? 2. What happens to disinfectants and their by-products when ingested or inhaled? 3. How can disinfectants and their by-products affect health? 4. Have disinfectants and their by-products affected human health? 5. What are the risks posed by disinfectants and their byproducts? 6. Conclusions 7. Other views
This is a faithful summary of the leading scientific consensus report produced in 2000 by the IPCS ( International Programme on Chemical Safety) "Executive Summary of the Environmental Health Criteria (EHC) 216: disinfectants and disinfectant by-products" More...
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/index.htm (1 of 2) [24/09/2004 10:06:38]
Download this study Top
Water Disinfectants : Level 1 - Summary on Water Disinfectants
Home > Studies > Water Disinfectants > Level 1
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
More
Info on our studies structure
Level 1 - Summary on Water Disinfectants 1. 2. 3. 4. 5. 6. 7.
What disinfectants and by-products are we talking about? What happens to disinfectants and their by-products when ingested or inhaled? How can disinfectants and their by-products affect health? Have disinfectants and their by-products affected human health? What are the risks posed by disinfectants and their by-products? Conclusions Other views
Level 1 Questions
Next Question
More in Details
Top
1. What disinfectants and by-products are we talking about? 1.1. Disinfectants such as chlorine, chloramines, ozone and chlorine dioxide are very important to protect drinking water against germs and fight disease transmitted through water. However, they can also react with natural material in the water to form unwanted by-products, which can be of concern to public health. More... 1.2. The formation of by-products depends on the disinfectant used, the chemical and physical characteristics of water and the treatment conditions. More... 1.3. While all disinfectants form by-products, different disinfectants form different by-products, for instance:
●
● ●
Chlorine can form halogenated by-products (i.e. that have chlorine or bromine incorporated into their structure) such as trihalomethanes and haloacetic acids. Ozone can form bromate. Chlorine dioxide can form chlorite and chlorate.
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (1 of 4) [24/09/2004 10:06:50]
Water Disinfectants : Level 1 - Summary on Water Disinfectants ●
All disinfectants form a variety of oxidation products that have not been well characterized. More...
1.4. There are several options to reduce the amount of disinfectant by-products in drinking water. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
2. What happens to disinfectants and their by-products when ingested or inhaled? Disinfectants still present in drinking water will react with saliva and stomach content to form disinfectant byproducts similar to those produced in water. The way disinfectant by-products are metabolised and eliminated depends on the by-product. Some will change to a harmless form but some can be converted into a form that can affect health. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
3. How can disinfectants and their by-products affect health? Disinfectants in drinking-water do not raise health concerns themselves at the levels used but some of their byproducts do:
●
● ●
Some chlorine by-products can harm the liver and kidney of laboratory animals given high doses and may even cause tumours. They do not appear to affect reproduction except at very high doses. Chlorine dioxide by-products can affect the red blood cells. Ozonation by-products can cause tumours in animals at high dose. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
4. Have disinfectants and their by-products affected human health? 4.1. Some studies in human populations seem to indicate that they may cause cancers of the bladder, colon and rectum, but the studies are not conclusive. Neither chlorinated nor chloraminated drinking-water appear to cause cardiovascular disease in humans. Other disinfectants have not been studied. More... 4.2. There is no convincing evidence that water chlorination can harm pregnancies or cause reproductive problems. More...
Conclusion
Level 1 Questions
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (2 of 4) [24/09/2004 10:06:50]
More in Details
Water Disinfectants : Level 1 - Summary on Water Disinfectants
Next Question
Top
5. What are the risks posed by disinfectants and their by-products? 5.1. The World Health Organization (WHO) has set intake limits for most disinfectants and by-products. These are used for developing the WHO drinking water guidelines that are, in turn, used by many countries as a basis for their drinking water standards. More... 5.2. Several milligrams of disinfectant per litre of water are typically employed in treatment plants, but what arrives at the tap is generally considerably less and well below the WHO guidelines. The concentration of disinfectant byproducts varies according to the properties of the water and the amount of natural organic matter it contains. More... 5.3. Potential human health effects would depend on both the concentration of disinfectant by-products and the length and timing of exposure. However, it is difficult to measure actual exposure levels and to take into account all possible risk factors. More... 5.4. Studies on human populations are useful but those on population studies of disinfectant by-products in particular have been but often difficult to interpret. Available studies are insufficient to establish that water disinfectants and their by-products affect health. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
6. Conclusions Since disinfection is a very important barrier to waterborne disease, it should never be compromised in attempting to control disinfection by-products. Studies to date do not provide sufficient evidence to say that exposure to disinfectant by-products actually causes cancer or affects reproduction. However, it is prudent to take steps to limit the exposure to disinfectant by-products where this can be achieved without compromising disinfection effectiveness. More...
Conclusion
Level 1 Questions
More in Details
Top
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (3 of 4) [24/09/2004 10:06:50]
Water Disinfectants : Level 1 - Summary on Water Disinfectants
7. Other views This summary is based on the latest International Programme on Chemical Safety (IPCS) review on Disinfectants and disinfectant by-products, EHC216. It is considered by most scientists as a consensus document and other recent scientific assessments reach similar conclusions - click here for some links. However, some institutions take a different approach - click here for some links.
Conclusion
Send this page 23-Sep-2004
Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (4 of 4) [24/09/2004 10:06:50]
Download this study Top
Other views on Water Disinfectants
About the Toolbox | Back | Print | Forward
Other views on Water Disinfectants The links on this page have been selected as examples of views that differ from that of the IPCS. This list of links is only a sample and neither pretends to be complete nor fully representative of all the views available. GreenFacts takes no position concerning the views expressed in these linked documents.
Is the IPCS report a consensus one? Most scientists globally agree with the conclusions of the Executive Summary of the Environmental Health Criteria (EHC) 216: disinfectants and disinfectant by-products, produced in 2000. An other institution having reached similar conclusions: ●
The UK Committee on Carcinogenicity in Food, Consumer Products and the Environment (COC), discusses conclusions in its 1999 Annual Report (p.59-61): www.advisorybodies.doh.gov.uk/coc/1999ar.pdf
Some institutions take a different risk approach Certain institutions consider that water disinfectants present a quantifiable health risk. ●
●
Health Canada states its position on chlorine by-products (CBPs): www.hc-sc.gc.ca/pphb-dgspsp/publicat/ cdic-mcc/19-3/c_e.html The EPA regulations addressing disinfection by-products (DBPs): Stage 1: www.epa.gov/OGWDW/mdbp/noda2.html Stage 2: www.epa.gov/safewater/stage2/ The links on this page have been selected as examples of views that differ from that of the IPCS. This list of links is only a sample and neither pretends to be complete nor fully representative of all the views available. GreenFacts takes no position concerning the views expressed in these linked documents.
Back | Print | Forward 30-Aug-2004
http://www.greenfacts.org/water-disinfectants/links/other-views.htm (1 of 2) [24/09/2004 10:06:57]
Top
Water Disinfectants : Level 2 - Details on Water Disinfectants
Home > Studies > Water Disinfectants > Level 2 > Questions
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Info on our studies structure
Level 2 - Details on Water Disinfectants ●
1. What disinfectants and by-products are we talking about? ❍ 1.1. Why is there concern about water disinfectants? ❍ 1.2. How are disinfectant by-products formed? ❍ 1.3. What are the most relevant disinfectant by-products? ❍ 1.4. How can the amount of disinfectant by-products be reduced?
●
2. What happens to disinfectants and their by-products when ingested or inhaled?
●
3. How can disinfectants and their by-products affect health?
●
●
4. Have disinfectants and their by-products affected human health? ❍ 4.1. Has water disinfection caused cardiovascular disease or cancer? ❍ 4.2. Has water disinfection harmed pregnancies? 5. What are the risks posed by disinfectants and their by-products? ❍ 5.1. What tolerable daily intakes and guideline values has the WHO set? ❍ 5.2. How much disinfectants and by-products are we exposed to? ❍ 5.3. Are there uncertainties in assessing exposure? ❍ 5.4. Have epidemiological studies been able to evaluate the risks?
●
6. Conclusions
●
7. Other views (level 1 only)
Back to Summary
Send this page 23-Sep-2004
Level 2 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/index.htm (1 of 2) [24/09/2004 10:07:15]
More in the Source Document
Download this study Top
More
Water Disinfectants : 1. What disinfectants and by-products are we talking about?
Home > Studies > Water Disinfectants > Level 2 > Question 1
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Level 1 Questions
More
Next Question
1. What disinfectants and by-products are we talking about? 1.1. 1.2. 1.3. 1.4.
Why is there concern about water disinfectants? How are disinfectant by-products formed? What are the most relevant disinfectant by-products? How can the amount of disinfectant by-products be reduced?
1.1. Why is there concern about water disinfectants? Chlorine has been used very widely to kill germs in drinking water and fight waterborne disease. However chlorine reacts with natural material in the water to form a range of disinfectant by-products (DBPs) of public health concern. Therefore, alternative chemical disinfectants are increasingly being used, either alone, in addition to chlorine, or in combination with one another. They include ozone (O3), chlorine dioxide (ClO2) and chloramines (NH2Cl). However, each has been shown to form its own set of disinfectant by-products (DBPs). There is thus a need to better understand the health risks associated with each mode of disinfection and to decrease the chemical risk without compromising the microbiological safety of drinking water. More...
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-1.htm (1 of 3) [24/09/2004 10:07:19]
Water Disinfectants : 1. What disinfectants and by-products are we talking about?
1.2. How are disinfectant by-products formed? Disinfectant by-products (DBPs) are formed when chemical disinfectants react in the water either with natural organic matter (NOM) or with bromide ions (Br-). Natural organic matter (NOM) comes mainly from the breakdown of plants and organic matter in soil and Br- comes from natural sources and from wastewater discharges. The reactions of disinfectants are influenced by the physical characteristics of the water, such as pH and temperature, and by treatment conditions, such as disinfectant dose. When inorganic bromide is present, it can also take part in the reaction to produce brominated by-products. When the disinfectant is chlorine, the reaction gives rise to halogenated (addition of chlorine or bromine) by-products such as trihalomethanes, haloacetic acids, chloral hydrate, haloketones, haloacetonitriles and halogenated hydroxyfuranone derivatives. When bromide is also present in the water, a mixture of different by-products containing varying amounts of chlorine and bromine will be formed. When the disinfectant is ozone, it oxidizes natural organic matter to form a number of by-products, with aldehydes being dominant. If bromide is present ozone can form brominated compounds similar to some of those produced by chlorine, and also inorganic bromate. When the disinfectant is chlorine dioxide, it does not appear to form many by-products, but it does break down to form chlorite and chlorate. When the disinfectant is chloramine, it generally leads to the formation of cyanogen chloride and significantly reduced levels of chlorine disinfectant by-products, but it can also form nitrite in the distribution system if it is not properly controlled. More...
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
1.3. What are the most relevant disinfectant by-products? When the disinfectant is chlorine, the predominant by-products are the trihalomethanes (THMs), followed by the haloacetic acids (HAAs). The THM usually present in highest concentration is chloroform, followed by dibromochloromethane. The HAAs present in the greatest concentrations are dichloroacetic acid and trichloroacetic acid. When the disinfectant is ozone, the most important by-product is bromate, which is present at very variable concentrations. When the disinfectant is chlorine dioxide, predictable quantities of chlorite and chlorate are formed, depending on the amount of chlorine dioxide used. Disinfectant by-products are usually present in complex mixtures that can vary greatly as conditions vary. The most widely studied process is chlorination and there are comparatively few studies on other disinfectants. More...
Back to Summary
Level 2 Questions
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-1.htm (2 of 3) [24/09/2004 10:07:19]
More in the Source Document
Water Disinfectants : 1. What disinfectants and by-products are we talking about?
Top
1.4. How can the amount of disinfectant by-products be reduced? The amounts of disinfectant by-products (DBPs) formed can be reduced by:
●
reducing DBP precursors (e.g. NOM, Br- ions) which react with disinfectants to form disinfectant by-products (DBPs): ❍
❍
●
limiting the amount of natural organic matter (NOM) in the water, using coagulation, granular activated carbon, membrane filtration or ozone biofiltration; protecting the quality of the water at the source.
optimizing the use of disinfectant by combining different disinfectants at different stages, i.e. at the treatment plant (primary disinfection) and in the distribution system (secondary disinfection). Ozone can be used exclusively as a primary disinfectant, chloramines exclusively as a secondary disinfectant, and both chlorine and to a lesser extent, chlorine dioxide, in either role. It is less usual for chloramines to be used as a primary disinfectant because it acts much more slowly. More...
Back to Summary
Level 2 Questions Level 1 Questions
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-1.htm (3 of 3) [24/09/2004 10:07:19]
More in the Source Document Next Question
Download this study Top
Water Disinfectants : 2. What happens to disinfectants and their by-products when ingested or inhaled?
Home > Studies > Water Disinfectants > Level 2 > Question 2
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Previous Question
Level 1 Questions
More
Next Question
2. What happens to disinfectants and their by-products when ingested or inhaled? 2.1. Some of the chlorine disinfectant can still be present in drinking water and react with saliva and stomach content, resulting in the formation of disinfectant by-products similar to those they produce in water. More... 2.2. The way chlorine by-products are metabolised depends on several factors:
●
●
●
● ●
Trihalomethanes (THMs) can be taken in by drinking the water and breathing its vapours (for example when showering). They are then metabolised and eliminated rapidly. Most THMs are metabolised into a less-toxic form, but some are transformed into more reactive substances, especially at high concentrations. Different haloacetic acids are eliminated differently. Dichloroacetic acid (DCA) is metabolised by forming both monochloroacetic acid and substances naturally found in human metabolism, the rate of conversion being dependent on the dose. trichloroacetic acid is partly metabolised to DCA, which then undergoes further conversion. Chloral hydrate undergoes several transformations in the body, leading to the formation of trichloroacetic and dichloroacetic acids (see above). Little is known about the elimination of haloacetonitriles. The most studied halogenated hydroxyfuranone derivative is called MX. Research indicates that MX is rapidly absorbed and excreted, mainly in urine but also in feces. MX itself cannot directly be measured in blood. More...
2.3. The main by-products of chlorine dioxide, chlorite and chlorate, are probably absorbed and largely broken down to chloride in the body. More... 2.4. Bromate formed during ozonation of the water is rapidly broken down to inorganic bromide and eliminated in urine. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-2.htm (1 of 2) [24/09/2004 10:07:23]
More in the Source Document Next Question
Download this study Top
Water Disinfectants : 3. How can disinfectants and their by-products affect health?
Home > Studies > Water Disinfectants > Level 2 > Question 3
Scientific Facts on
Water Disinfectants & disinfectant by-products
Previous Question
Level 1 Questions
Source document: IPCS (2000) Summary & Details: GreenFacts (2004)
More
Next Question
3. How can disinfectants and their by-products affect health? 3.1. Disinfectants themselves, at the concentrations used, do not appear to contribute to toxicity but it is the byproducts and breakdown products that have received attention. Chlorine gas, chloramine and chlorine dioxide are strong respiratory irritants, but only at much higher exposure than would result from the release of vapors through from drinking-water. More... 3.2. The different groups of chlorine by-products have different toxicity. They can particularly affect the liver and kidney of laboratory rats and mice: ●
●
●
● ●
The toxicity of the trihalomethanes (THMs) in laboratory animals is higher when administered with corn oil than with water. Chloroform is not considered to be genotoxic and induces cancers only at high doses after tissues have been damaged. The other THMs appear to be weakly genotoxic. At high doses, some induce tumours of the liver and kidney and others of the large intestine, when administered in corn oil. The haloacetic acids (HAAs) produce a range of effects in rodents including tumours of the liver and reproductive and neurological effects, but only at very high doses. They are only weakly genotoxic but this does not appear to be how they cause tumours. Chloral hydrate has been shown to potentially induce liver tumours and other health effects in laboratory rodents but only at very high doses. Some of the other halogenated aldehydes and ketones are highly genotoxic possibly carcinogenic and one, chloroacetaldehyde has induced liver tumours in laboratory animals. The haloacetonitriles have not been well studied. Some are mutagenic, but may not induce tumours. MX is a very potent mutagen in bacteria and also appears to cause some tumours in laboratory rats. More...
3.3. The by-products of chlorine dioxide, chlorite and chlorate, can damage red blood cells. Chlorite may cause mild neurobehavioural effects in rat pups at relatively high doses but does not increase tumours in laboratory animals. Chlorate shows lower toxicity than chlorite. More... 3.4. Bromate, the main by-product of ozonation, has been shown to induce tumours of the kidney, peritoneum and thyroid in rodents at high doses. More...
Back to Summary
Level 2 Questions
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-3.htm (1 of 2) [24/09/2004 10:07:25]
More in the Source Document
Water Disinfectants : 3. How can disinfectants and their by-products affect health? Previous question
Send this page 23-Sep-2004
Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-3.htm (2 of 2) [24/09/2004 10:07:25]
Next question
Download this study Top
Water Disinfectants : 4. Have disinfectants and their by-products affected human health?
Home > Studies > Water Disinfectants > Level 2 > Question 4
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Previous Question
Level 1 Questions
More
Next Question
4. Have disinfectants and their by-products affected human health? 4.1. Has water disinfection caused cardiovascular disease or cancer? 4.2. Has water disinfection harmed pregnancies?
4.1. Has water disinfection caused cardiovascular disease or cancer? There are no indications that chlorinated or chloraminated drinking-water are a cause of cardiovascular disease in humans. Studies on other disinfectants have not been performed. Many epidemiological studies have been carried out on the possibility that chlorinated drinking water, and to a lesser extent chloramination, could contribute to cancer in human populations. There have been weak indications that the consumption of chlorinated drinking water may have increased the number of cancers of the bladder, rectum and colon in some studies. However, because the exposure to water contaminants was generally not adequately evaluated, there is no sufficient evidence to say that chlorinated drinking water was or was not the cause of these cancers. It is possible that the associations observed might be due to some other factors. There are no epidemiological studies on the carcinogenic effects of other disinfectants. More...
Back to Summary
Level 2 Questions
More in the Source Document
Top
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-4.htm (1 of 2) [24/09/2004 10:07:28]
Water Disinfectants : 4. Have disinfectants and their by-products affected human health?
4.2. Has water disinfection harmed pregnancies? Some studies of populations having consumed chlorinated water, have found small to moderate increased risks for some adverse birth outcomes such as miscarriage and neural tube defects. However, these studies are difficult to interpret because of methodological limitations or suspected bias and they need to be confirmed by other studies. The experts concluded that the results of currently published studies do not provide convincing evidence that chlorinated water or THMs cause adverse pregnancy outcomes. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-4.htm (2 of 2) [24/09/2004 10:07:28]
More in the Source Document Next Question
Download this study Top
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
Home > Studies > Water Disinfectants > Level 2 > Question 5
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants & disinfectant by-products
Previous Question
Level 1 Questions
Summary & Details: GreenFacts (2004)
More
Conclusions
5. What are the risks posed by disinfectants and their by-products? 5.1. 5.2. 5.3. 5.4.
What tolerable daily intakes and guideline values has the WHO set? How much disinfectants and by-products are we exposed to? Are there uncertainties in assessing exposure? Have epidemiological studies been able to evaluate the risks?
5.1. What tolerable daily intakes and guideline values has the WHO set? For disinfectants and disinfectant by-products (DBPs) with sufficient data, the World Health Organisation (WHO) has set safe acceptable intake levels. These levels are called Tolerable Daily Intakes (TDIs). TDIs are determined by taking the level at which no harmful health effect has been observed (No Observed Adverse Effect Level or NOAEL) in a particular animal species (e.g. mice, rats, hamsters) and applying an uncertainty factor (in this case, between 100 and 1000 depending on studies available and confidence in the results). These TDIs are used as a basis for developing the WHO drinking water guidelines that are, in turn, used by many countries, including the European Union (EU), as a basis for their drinking water standards. The guideline values are typically derived from the TDI assuming the average adult weighs 60 kg and drinks 2 litres of water per day. The following tables present TDIs for disinfectants and disinfectant by-products and the NOAELs from which they were derived. In addition to the data from the IPCS report, presented in the first two columns, a third column is added, which is based on the "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004, providing the most up-to-date guideline values in terms of concentrations in drinking water. 5.1.1. Disinfectants (More...) Table 1. Intake reference values for disinfectants NOAEL (µg/kg body weight) Chlorine
15 000
Tolerable Daily Intake (TDI) WHO drinking water guideline ( µg/kg body weight) value (µg/litre)* 150
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (1 of 6) [24/09/2004 10:07:31]
5 000
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
Monochloramine Chlorine dioxide (1) (based on chlorite)
9 400
94
3 000
2 900 (chlorite)
30
700 (chlorite)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004
5.1.2. Chlorine by-products (More...) Table 2. Intake reference values for chlorine by-products NOAEL (µg/kg body weight)
Tolerable Daily Intake (TDI) WHO drinking water guideline (µg/kg body weight) value (µg/litre)*
Trihalomethanes
(1 )
-BDCM
-
-
60 (2)
-DBCM
30 000
30
100
-Bromoform
25 000
25
100
-Chloroform
10 000
10
200
Haloacetic acids
(3 )
-DCA
40 000
40
50
-TCA
40 000
40
200
160 000
16
10 (4)
Chloral hydrate Haloacetonitriles
(5 )
-DCAN
15 000
15
20
-DBAN
23 000
23
70
MX
Not established (6)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004
5.1.3. Chlorine dioxide by-products Table 3. Intake reference values for chlorine dioxide by-products
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (2 of 6) [24/09/2004 10:07:31]
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
NOAEL (µg/kg body weight)
Tolerable Daily Intake (TDI) WHO drinking water guideline (µg/kg body weight) value (µg/litre)*
Chlorite
2 900
30
700
(1)
Chlorate
30 000
30
700
(1)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004
Notes referring to the above table 1: The Tolerable Daily Intake (TDI) for chlorite and for chlorate has translated into a WHO provisional drinking water guideline value. The TDI reflects current lack of a specific long-term study which is in progress. More... 5.1.4. Ozonation by-products (More...) Table 4. Intake reference values for ozonation by-products NOAEL (µg/kg body weight) Bromate
Tolerable Daily Intake (TDI) WHO drinking water guideline (µg/kg body weight) value (µg/litre)*
1 300
1
10
(1)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004 Notes referring to the above table 1: At present there are conflicting data regarding the exact mechanism by which bromate causes cancer in laboratory animals and how that would impact on risk assessment. The WHO has developed a drinking water guideline value of 10 µg/litre based on two approaches and taking into account the practicality of using ozone. Where bromide is present in the raw water, the guideline value can only be achieved by appropriate control of disinfection conditions.
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (3 of 6) [24/09/2004 10:07:31]
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
5.2. How much disinfectants and by-products are we exposed to? Typically, several milligrams of disinfectant per litre (mg/l) of water are employed in the system, corresponding to the dose necessary to kill the microorganisms in the treatment plant (primary disinfection) and the dose necessary to maintain a residual disinfection in the distribution system (secondary disinfection). The concentration at the tap is considerably less than initially injected. The concentrations of disinfection by-products will vary according to the raw water quality and its physical and chemical properties such as pH and temperature, and the level of drink-water treatment. Chlorine by-products:
●
●
●
Trihalomethanes (THMs) are normally dominated by chloroform but the levels of brominated THMs will depend on the bromide present in the water. The concentration of total haloacetic acids (HAA) is generally about half of the total THMs but it is quite difficult to generalize. Dichloroacetic acid (DCA) and trichloroacetic acid (TCA) are the first and second most dominant species. If a hypochlorite solution is used instead of chlorine gas, chlorate may also occur during chlorination.
When the disinfectant is chloramine, the by-products depend on the mode of chloramination, application of ammonia followed by chlorine leading to lower levels of chlorine by-products. Bromate is primarily formed by ozonation of water containing bromide: about 50% of the bromide is converted to bromate. In European water treatment plants, the concentration of bromate was found to be a maximum of 16 mg per litre. When the disinfectant is chlorine dioxide, about 50 to 70% of the applied dose forms chlorite. More...
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
5.3. Are there uncertainties in assessing exposure? Toxicological studies attempt to extrapolate the results of laboratory animal studies to humans. This may lead to an estimation of risk factors for some health effects. Epidemiological studies attempt to link human health effects (e.g. cancer) to a cause (e.g. exposure to a disinfectant by-product, DBP) and require exposure assessments. Humans can be exposed to chemical risks from disinfected drinking-water through several routes:
● ●
●
ingestion of disinfectant by-products (DBPs) in drinking-water; ingestion of drinking-water that has a residual of free chlorine at the tap and the resulting formation of DBPs in the mouth and stomach (ozone cannot be present at the tap and chloramines and chlorine dioxide do not react to form by-products); inhalation of volatile DBPs during showering.
However, it is generally assumed that the most significant route is the ingestion of DBPs. Human health effects depend on both DBP concentration and duration of exposure. They are difficult to assess
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (4 of 6) [24/09/2004 10:07:31]
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
because DBP mixtures: ●
●
●
are complex, e.g. trihalomethanes (THMs) versus haloacetic acids (HAAs), chlorinated versus brominated species ; change with time, as a function of temperature, nature and concentration of natural organic matters (NOM) in the source water ; change with location, i.e. throughout a distribution system.
For epidemiological studies, some historical databases exist for disinfectant doses (e.g. chlorine) and possibly for DBP precursors (e.g. total organic carbon, TOC) and THM concentrations. In contrast, data for HAAs, bromate and chlorite are much more recent and hence sparse. When DBP data is not available, exposure can be estimated indirectly from the chlorine dose and other data. More...
Back to Summary
Level 2 Questions
More in the Source Document
Top
5.4. Have epidemiological studies been able to evaluate the risks? 5.4.1. Epidemiological studies are a very valuable tool in determining the possible risks from exposure to environmental chemicals. However, there are limitations to the use of Epidemiological studies because it is generally difficult to measure individual exposure to the chemical accurately and because there are usually other causes of the effect of interest, such as smoking or diet. This is also true for epidemiological studies of disinfectant by-products (DBPs). There is often no information on individual water consumption and generally very little information on the concentrations of DBPs other than trihalomethanes (THMs). Another important point for epidemiology is the consistency of the results between different studies. There have been more studies looking at bladder cancer than any other cancer but the evidence is not consistent. Some studies show an increased risk while others do not. In those that do show an increased risk, there are differences in the risk reported and between the sexes and smokers and non-smokers. More... 5.4.2. The epidemiological studies available provide insufficient evidence to establish that water disinfectants and their by-products cause any of the observed effects, mainly because of incomplete information about exposures to specific water contaminants. Risks may be due to other water contaminants or to other factors not taken into consideration. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (5 of 6) [24/09/2004 10:07:31]
More in the Source Document Conclusions
Download this study Top
Water Disinfectants : 6. Conclusions
Home > Studies > Water Disinfectants > Level 2 > Question 6
Scientific Facts on
Water Disinfectants & disinfectant by-products
Previous Question
Source document: IPCS (2000) Summary & Details: GreenFacts (2004)
More
Level 1 Questions
6. Conclusions Disinfection is, without question, one of the most important barriers to waterborne disease in most parts of the world. As a consequence disinfection should never be compromised in attempting to control disinfection by-products. The risks of illness and death from germs in drinking water is very much greater than the risks from disinfectants and disinfection by-products. However, actions have been taken to reduce the levels of DBPs. Chlorine and alternative chemical disinfectants (ozone, chlorine dioxide and chloramine) all lead to the formation of disinfectant by-products (DBPs). Currently, the DBPs of most concern include trihalomethanes (THMs), haloacetic acids (HAAs), bromate and chlorite. The toxicology of the DBPs suggests that the likelihood of adverse effects is not significantly different between different disinfection options. Animal studies indicate that none of the chlorination by-products studied to date is a potent carcinogen at concentrations normally found in drinking water. There is insufficient epidemiological evidence to conclude that drinking chlorinated water causes cancers. The results of currently published studies do not provide convincing evidence that chlorinated water or THMs cause adverse pregnancy outcomes. Nevertheless it is prudent to take steps to minimise exposure to DBPs, where this can be achieved without compromising disinfection. Strategies should focus on eliminating organic impurities fostering DBP formation. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions
More in the Source Document
Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-99.htm (1 of 2) [24/09/2004 10:07:36]
Download this study Top
GreenFacts: Factual Water Disinfectant Links
Home > Studies > Water Disinfectants > Links
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Create a link to our Water Disinfectant study
Water Disinfectant Links Factual Water Disinfectant Links - endorsed by the
GreenFacts Scientific Board
Some of the websites providing reliable scientific information on water disinfectants: Some Q&As & FAQs on water disinfectants More Info for the non-specialist Some water disinfectant News Sites Policy related websites
1. 2. 3. 4.
Other Links - not necessarily endorsed by the GreenFacts Scientific Board ● ●
Other Views suggesting that Water Disinfectants pose either more or less risks Sites linking to this study
Create a link to our Water Disinfectant study
http://www.greenfacts.org/water-disinfectants/links/index.htm (1 of 4) [24/09/2004 10:07:41]
Top
More
GreenFacts: Factual Water Disinfectant Links
1. Some Water Disinfectants Q&As & FAQs ●
●
●
●
The UK Drinking Water Inspectorate (DWI) discusses chlorine water disinfection at: http://www.dwi.gov.uk/consumer/faq/chlorine.htm (2002). The San Francisco Public Utilities Commission (SFPUC) answers questions about water disinfectants at: http://sfwater.org/detail.cfm/MC_ID/10/MSC_ID/51/MTO_ID/NULL/C_ID /654#trihalomethanes The City of Ottawa in Canada also answers questions relating to chloramine disinfection at: http://www.city.ottawa.on.ca/city_services/water/27_2_5_2_1_en.shtml (2004). ToxFAQs by the American Toxic Substances and Disease Registry (ATSDR): http://www.atsdr.cdc.gov/toxfaq.html addressing the following water disinfectants: chlorine, chlorine dioxide and chlorite,bromoform & chlorodibromomethane and chloroform (1997-2002).
Create a link to our Water Disinfectant study
Top
2. Some More Information for the Non-specialist ●
●
●
●
●
●
●
The International Water Association (IWA) explains the practice of chlorination at: http://www.iwahq.org.uk//template.cfm?name=bp0004 The National Toxicology Program's factsheet of it Safe Drinking Water Program at the US National Institute of Environmental Health Science (NIEHS) is presented at: http://ntp-server.niehs.nih.gov/htdocs/liason/factsheets/DrinkingWaterFacts.html (2002). The Aquastel group provides a table with the properties of several water disinfectants at: http://www.aquastel.com/comparison.shtml An index to drinking water facts by the Australia's Cooperative Research Centre for Water Quality and Treatment (CRC) is presented at: http://www.waterquality.crc.org.au/aboutdw_dwfacts.htm, including documents on water treatment and water safety. Information on pre-treatment and chemical water treatment from the World Health Organization (WHO) is presented at: http://www.who.int/water_sanitation_health/dwq/wsh0207/en/index6.html (2004). The US Centre for Disease Control (CDC) discusses variety of conclusions at: http://www.cdc.gov/safewater/thm.htm The Chlorine Chemistry Council (CCC) provides information on water disinfection at: http://c3.org/chlorine_knowledge_center/index.html#3
http://www.greenfacts.org/water-disinfectants/links/index.htm (2 of 4) [24/09/2004 10:07:41]
GreenFacts: Factual Water Disinfectant Links Create a link to our Water Disinfectant study
Top
3. Some Water Disinfectants News Sites ●
●
●
●
The US Water Quality and Health Council (WQHC) has drinking water news at: http://www.waterandhealth.org/drinkingwater/ Recent news on water quality provided by the Water Environment Federation (WEF) at: http://www.wef.org/WaterNews/ The American Water Works Association (AWWA) "Waterweek" news at: http://www.awwa.org/communications/waterweek/ The US Environmental Protection Agency (EPA) general drinking water information can be accessed through their Ground Water & Drinking Water website: http://www.epa.gov/safewater/
Create a link to our Water Disinfectant study
Top
4. Some Policy-related Websites ●
●
The WHO Guidelines for drinking water quality are presented at: http://www.who.int/docstore/water_sanitation_health/GDWQ/Updating/ draftguidel/draftchap87c.htm#8.7.4 The US Environmental Protection Agency (EPA) presents its policy at: http://www.epa.gov/ebtpages/watewaterdisinfectionbyproducts.html The US EPA is currently drawing up new regulations regarding DBPs. These developments can be followed from: http://www.epa.gov/safewater/mdbp.html
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/links/index.htm (3 of 4) [24/09/2004 10:07:41]
Download this study Top
GreenFacts : About this study on Water Disinfectants
Home > Studies > Water Disinfectants > About this study
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants & disinfectant by-products
Summary & Details: GreenFacts (2004)
More
GreenFacts Copyright Policy
About this Water Disinfectant study 1. Sources for this Study 2. Current Status 3. Study Publication History
1. Sources for this Study The material content of the texts on Level 3 are directly sourced from the Executive Summary of the Environmental Health Criteria (EHC) 216: disinfectants and disinfectant by-products, a leading scientific report produced in 2000 by a large international panel of scientists of the IPCS (International Programme on Chemical Safety). The Levels 1 & 2 were written by Dr. John Fawell in collaboration with the
GreenFacts team.
More on the Source and Copyright
2. Current Status Second draft completed and preliminary review on-going.
3. Study Publication History The GreenFacts publication process is designed to ensure as high a degree of objectivity as possible.
First draft The first draft of this study was produced by Dr. John Fawell on November 2003 on the basis of a canvas prepared by the GreenFacts team.
http://www.greenfacts.org/water-disinfectants/about-water-disinfectants.htm (1 of 3) [24/09/2004 10:07:46]
GreenFacts : About this study on Water Disinfectants
Second draft The second draft of this study has been produced in February 2004 by Dr. John Fawell after review by the GreenFacts team.
Preliminary review The final draft of this study will be produced in early 2004 by Dr. John Fawell after pre-review by experts from environmental and industrial organizations (see our pre review form).
Peer review The final draft will be peer reviewed by 3 independent scientists selected by the GreenFacts Scientific Board (see peer review form) and final corrections will be added under the supervision of the GreenFacts Scientific Board
our
in early 2004.
Publication Final publication will be authorized by the President of the GreenFacts Scientific Board in early 2004.
Updates or subsequent post-publication revisions No update or revision at present. GreenFacts Copyright Policy
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/about-water-disinfectants.htm (2 of 3) [24/09/2004 10:07:46]
Download this study Top
IPCS
About the Toolbox | Back | Print | Forward
International Programme on Chemical Safety IPCS Home page |
About IPCS
The International Programme on Chemical Safety (IPCS) was established in 1980 by the WHO, the UNEP and the ILO (International Labour Organisation) "for the early warning and prevention of harmful effects of chemicals to which humans were being increasingly exposed, and for the assessment of the potential risks to human health." It has collaborated to and published many highly recognized scientific publication. Most publications are availaible from the INCHEM website www.inchem.org, "a means of rapid access to internationally peer reviewed information on chemicals commonly used throughout the world, which may also occur as contaminants in the environment and food." Publications include: ●
●
About 250 "Environment Health Criteria" monographs (EHCs), available at www.inchem.org/pages/ehc.html About 50 "Concise International Chemical Assessment Document" (CICADs), available at www.inchem.org/pages/cicads.html
IPCS publications not published on the INCHEM website are posted at IPCS Home page |
www.who.int/pcs/
About IPCS
Back | Print | Forward 05-Aug-2004
http://www.greenfacts.org/links/site-boxes/ipcs.htm (1 of 2) [24/09/2004 10:07:55]
Top
Home > Studies > Water Disinfectants
Scientific Facts on
Water Disinfectants & disinfectant by-products
Source document: IPCS (2000) Summary & Details: GreenFacts (2004)
More
Questions and Answers presented in 3 levels of increasing detail.
Questions on Water Disinfectants
Context - To protect drinking water against germs and fight disease transmitted through water, disinfectants such as chlorine, chloramines, ozone and chlorine dioxide are used. These disinfectants can react with natural material in the water to form certain unwanted by-products, which raise health concerns.
1. What disinfectants and by-products are we talking about? 2. What happens to disinfectants and their by-products when ingested or inhaled? 3. How can disinfectants and their by-products affect health? 4. Have disinfectants and their by-products affected human health? 5. What are the risks posed by disinfectants and their byproducts? 6. Conclusions 7. Other views
This is a faithful summary of the leading scientific consensus report produced in 2000 by the IPCS ( International Programme on Chemical Safety) "Executive Summary of the Environmental Health Criteria (EHC) 216: disinfectants and disinfectant by-products" More...
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/index.htm (1 of 2) [24/09/2004 10:06:38]
Download this study Top
Water Disinfectants : Level 1 - Summary on Water Disinfectants
Home > Studies > Water Disinfectants > Level 1
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
More
Info on our studies structure
Level 1 - Summary on Water Disinfectants 1. 2. 3. 4. 5. 6. 7.
What disinfectants and by-products are we talking about? What happens to disinfectants and their by-products when ingested or inhaled? How can disinfectants and their by-products affect health? Have disinfectants and their by-products affected human health? What are the risks posed by disinfectants and their by-products? Conclusions Other views
Level 1 Questions
Next Question
More in Details
Top
1. What disinfectants and by-products are we talking about? 1.1. Disinfectants such as chlorine, chloramines, ozone and chlorine dioxide are very important to protect drinking water against germs and fight disease transmitted through water. However, they can also react with natural material in the water to form unwanted by-products, which can be of concern to public health. More... 1.2. The formation of by-products depends on the disinfectant used, the chemical and physical characteristics of water and the treatment conditions. More... 1.3. While all disinfectants form by-products, different disinfectants form different by-products, for instance:
●
● ●
Chlorine can form halogenated by-products (i.e. that have chlorine or bromine incorporated into their structure) such as trihalomethanes and haloacetic acids. Ozone can form bromate. Chlorine dioxide can form chlorite and chlorate.
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (1 of 4) [24/09/2004 10:06:50]
Water Disinfectants : Level 1 - Summary on Water Disinfectants ●
All disinfectants form a variety of oxidation products that have not been well characterized. More...
1.4. There are several options to reduce the amount of disinfectant by-products in drinking water. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
2. What happens to disinfectants and their by-products when ingested or inhaled? Disinfectants still present in drinking water will react with saliva and stomach content to form disinfectant byproducts similar to those produced in water. The way disinfectant by-products are metabolised and eliminated depends on the by-product. Some will change to a harmless form but some can be converted into a form that can affect health. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
3. How can disinfectants and their by-products affect health? Disinfectants in drinking-water do not raise health concerns themselves at the levels used but some of their byproducts do:
●
● ●
Some chlorine by-products can harm the liver and kidney of laboratory animals given high doses and may even cause tumours. They do not appear to affect reproduction except at very high doses. Chlorine dioxide by-products can affect the red blood cells. Ozonation by-products can cause tumours in animals at high dose. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
4. Have disinfectants and their by-products affected human health? 4.1. Some studies in human populations seem to indicate that they may cause cancers of the bladder, colon and rectum, but the studies are not conclusive. Neither chlorinated nor chloraminated drinking-water appear to cause cardiovascular disease in humans. Other disinfectants have not been studied. More... 4.2. There is no convincing evidence that water chlorination can harm pregnancies or cause reproductive problems. More...
Conclusion
Level 1 Questions
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (2 of 4) [24/09/2004 10:06:50]
More in Details
Water Disinfectants : Level 1 - Summary on Water Disinfectants
Next Question
Top
5. What are the risks posed by disinfectants and their by-products? 5.1. The World Health Organization (WHO) has set intake limits for most disinfectants and by-products. These are used for developing the WHO drinking water guidelines that are, in turn, used by many countries as a basis for their drinking water standards. More... 5.2. Several milligrams of disinfectant per litre of water are typically employed in treatment plants, but what arrives at the tap is generally considerably less and well below the WHO guidelines. The concentration of disinfectant byproducts varies according to the properties of the water and the amount of natural organic matter it contains. More... 5.3. Potential human health effects would depend on both the concentration of disinfectant by-products and the length and timing of exposure. However, it is difficult to measure actual exposure levels and to take into account all possible risk factors. More... 5.4. Studies on human populations are useful but those on population studies of disinfectant by-products in particular have been but often difficult to interpret. Available studies are insufficient to establish that water disinfectants and their by-products affect health. More...
Conclusion
Level 1 Questions
Next Question
More in Details
Top
6. Conclusions Since disinfection is a very important barrier to waterborne disease, it should never be compromised in attempting to control disinfection by-products. Studies to date do not provide sufficient evidence to say that exposure to disinfectant by-products actually causes cancer or affects reproduction. However, it is prudent to take steps to limit the exposure to disinfectant by-products where this can be achieved without compromising disinfection effectiveness. More...
Conclusion
Level 1 Questions
More in Details
Top
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (3 of 4) [24/09/2004 10:06:50]
Water Disinfectants : Level 1 - Summary on Water Disinfectants
7. Other views This summary is based on the latest International Programme on Chemical Safety (IPCS) review on Disinfectants and disinfectant by-products, EHC216. It is considered by most scientists as a consensus document and other recent scientific assessments reach similar conclusions - click here for some links. However, some institutions take a different approach - click here for some links.
Conclusion
Send this page 23-Sep-2004
Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/water-disinfectants.htm (4 of 4) [24/09/2004 10:06:50]
Download this study Top
Other views on Water Disinfectants
About the Toolbox | Back | Print | Forward
Other views on Water Disinfectants The links on this page have been selected as examples of views that differ from that of the IPCS. This list of links is only a sample and neither pretends to be complete nor fully representative of all the views available. GreenFacts takes no position concerning the views expressed in these linked documents.
Is the IPCS report a consensus one? Most scientists globally agree with the conclusions of the Executive Summary of the Environmental Health Criteria (EHC) 216: disinfectants and disinfectant by-products, produced in 2000. An other institution having reached similar conclusions: ●
The UK Committee on Carcinogenicity in Food, Consumer Products and the Environment (COC), discusses conclusions in its 1999 Annual Report (p.59-61): www.advisorybodies.doh.gov.uk/coc/1999ar.pdf
Some institutions take a different risk approach Certain institutions consider that water disinfectants present a quantifiable health risk. ●
●
Health Canada states its position on chlorine by-products (CBPs): www.hc-sc.gc.ca/pphb-dgspsp/publicat/ cdic-mcc/19-3/c_e.html The EPA regulations addressing disinfection by-products (DBPs): Stage 1: www.epa.gov/OGWDW/mdbp/noda2.html Stage 2: www.epa.gov/safewater/stage2/ The links on this page have been selected as examples of views that differ from that of the IPCS. This list of links is only a sample and neither pretends to be complete nor fully representative of all the views available. GreenFacts takes no position concerning the views expressed in these linked documents.
Back | Print | Forward 30-Aug-2004
http://www.greenfacts.org/water-disinfectants/links/other-views.htm (1 of 2) [24/09/2004 10:06:57]
Top
Water Disinfectants : Level 2 - Details on Water Disinfectants
Home > Studies > Water Disinfectants > Level 2 > Questions
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Info on our studies structure
Level 2 - Details on Water Disinfectants ●
1. What disinfectants and by-products are we talking about? ❍ 1.1. Why is there concern about water disinfectants? ❍ 1.2. How are disinfectant by-products formed? ❍ 1.3. What are the most relevant disinfectant by-products? ❍ 1.4. How can the amount of disinfectant by-products be reduced?
●
2. What happens to disinfectants and their by-products when ingested or inhaled?
●
3. How can disinfectants and their by-products affect health?
●
●
4. Have disinfectants and their by-products affected human health? ❍ 4.1. Has water disinfection caused cardiovascular disease or cancer? ❍ 4.2. Has water disinfection harmed pregnancies? 5. What are the risks posed by disinfectants and their by-products? ❍ 5.1. What tolerable daily intakes and guideline values has the WHO set? ❍ 5.2. How much disinfectants and by-products are we exposed to? ❍ 5.3. Are there uncertainties in assessing exposure? ❍ 5.4. Have epidemiological studies been able to evaluate the risks?
●
6. Conclusions
●
7. Other views (level 1 only)
Back to Summary
Send this page 23-Sep-2004
Level 2 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/index.htm (1 of 2) [24/09/2004 10:07:15]
More in the Source Document
Download this study Top
More
Water Disinfectants : 1. What disinfectants and by-products are we talking about?
Home > Studies > Water Disinfectants > Level 2 > Question 1
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Level 1 Questions
More
Next Question
1. What disinfectants and by-products are we talking about? 1.1. 1.2. 1.3. 1.4.
Why is there concern about water disinfectants? How are disinfectant by-products formed? What are the most relevant disinfectant by-products? How can the amount of disinfectant by-products be reduced?
1.1. Why is there concern about water disinfectants? Chlorine has been used very widely to kill germs in drinking water and fight waterborne disease. However chlorine reacts with natural material in the water to form a range of disinfectant by-products (DBPs) of public health concern. Therefore, alternative chemical disinfectants are increasingly being used, either alone, in addition to chlorine, or in combination with one another. They include ozone (O3), chlorine dioxide (ClO2) and chloramines (NH2Cl). However, each has been shown to form its own set of disinfectant by-products (DBPs). There is thus a need to better understand the health risks associated with each mode of disinfection and to decrease the chemical risk without compromising the microbiological safety of drinking water. More...
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-1.htm (1 of 3) [24/09/2004 10:07:19]
Water Disinfectants : 1. What disinfectants and by-products are we talking about?
1.2. How are disinfectant by-products formed? Disinfectant by-products (DBPs) are formed when chemical disinfectants react in the water either with natural organic matter (NOM) or with bromide ions (Br-). Natural organic matter (NOM) comes mainly from the breakdown of plants and organic matter in soil and Br- comes from natural sources and from wastewater discharges. The reactions of disinfectants are influenced by the physical characteristics of the water, such as pH and temperature, and by treatment conditions, such as disinfectant dose. When inorganic bromide is present, it can also take part in the reaction to produce brominated by-products. When the disinfectant is chlorine, the reaction gives rise to halogenated (addition of chlorine or bromine) by-products such as trihalomethanes, haloacetic acids, chloral hydrate, haloketones, haloacetonitriles and halogenated hydroxyfuranone derivatives. When bromide is also present in the water, a mixture of different by-products containing varying amounts of chlorine and bromine will be formed. When the disinfectant is ozone, it oxidizes natural organic matter to form a number of by-products, with aldehydes being dominant. If bromide is present ozone can form brominated compounds similar to some of those produced by chlorine, and also inorganic bromate. When the disinfectant is chlorine dioxide, it does not appear to form many by-products, but it does break down to form chlorite and chlorate. When the disinfectant is chloramine, it generally leads to the formation of cyanogen chloride and significantly reduced levels of chlorine disinfectant by-products, but it can also form nitrite in the distribution system if it is not properly controlled. More...
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
1.3. What are the most relevant disinfectant by-products? When the disinfectant is chlorine, the predominant by-products are the trihalomethanes (THMs), followed by the haloacetic acids (HAAs). The THM usually present in highest concentration is chloroform, followed by dibromochloromethane. The HAAs present in the greatest concentrations are dichloroacetic acid and trichloroacetic acid. When the disinfectant is ozone, the most important by-product is bromate, which is present at very variable concentrations. When the disinfectant is chlorine dioxide, predictable quantities of chlorite and chlorate are formed, depending on the amount of chlorine dioxide used. Disinfectant by-products are usually present in complex mixtures that can vary greatly as conditions vary. The most widely studied process is chlorination and there are comparatively few studies on other disinfectants. More...
Back to Summary
Level 2 Questions
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-1.htm (2 of 3) [24/09/2004 10:07:19]
More in the Source Document
Water Disinfectants : 1. What disinfectants and by-products are we talking about?
Top
1.4. How can the amount of disinfectant by-products be reduced? The amounts of disinfectant by-products (DBPs) formed can be reduced by:
●
reducing DBP precursors (e.g. NOM, Br- ions) which react with disinfectants to form disinfectant by-products (DBPs): ❍
❍
●
limiting the amount of natural organic matter (NOM) in the water, using coagulation, granular activated carbon, membrane filtration or ozone biofiltration; protecting the quality of the water at the source.
optimizing the use of disinfectant by combining different disinfectants at different stages, i.e. at the treatment plant (primary disinfection) and in the distribution system (secondary disinfection). Ozone can be used exclusively as a primary disinfectant, chloramines exclusively as a secondary disinfectant, and both chlorine and to a lesser extent, chlorine dioxide, in either role. It is less usual for chloramines to be used as a primary disinfectant because it acts much more slowly. More...
Back to Summary
Level 2 Questions Level 1 Questions
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-1.htm (3 of 3) [24/09/2004 10:07:19]
More in the Source Document Next Question
Download this study Top
Water Disinfectants : 2. What happens to disinfectants and their by-products when ingested or inhaled?
Home > Studies > Water Disinfectants > Level 2 > Question 2
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Previous Question
Level 1 Questions
More
Next Question
2. What happens to disinfectants and their by-products when ingested or inhaled? 2.1. Some of the chlorine disinfectant can still be present in drinking water and react with saliva and stomach content, resulting in the formation of disinfectant by-products similar to those they produce in water. More... 2.2. The way chlorine by-products are metabolised depends on several factors:
●
●
●
● ●
Trihalomethanes (THMs) can be taken in by drinking the water and breathing its vapours (for example when showering). They are then metabolised and eliminated rapidly. Most THMs are metabolised into a less-toxic form, but some are transformed into more reactive substances, especially at high concentrations. Different haloacetic acids are eliminated differently. Dichloroacetic acid (DCA) is metabolised by forming both monochloroacetic acid and substances naturally found in human metabolism, the rate of conversion being dependent on the dose. trichloroacetic acid is partly metabolised to DCA, which then undergoes further conversion. Chloral hydrate undergoes several transformations in the body, leading to the formation of trichloroacetic and dichloroacetic acids (see above). Little is known about the elimination of haloacetonitriles. The most studied halogenated hydroxyfuranone derivative is called MX. Research indicates that MX is rapidly absorbed and excreted, mainly in urine but also in feces. MX itself cannot directly be measured in blood. More...
2.3. The main by-products of chlorine dioxide, chlorite and chlorate, are probably absorbed and largely broken down to chloride in the body. More... 2.4. Bromate formed during ozonation of the water is rapidly broken down to inorganic bromide and eliminated in urine. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-2.htm (1 of 2) [24/09/2004 10:07:23]
More in the Source Document Next Question
Download this study Top
Water Disinfectants : 3. How can disinfectants and their by-products affect health?
Home > Studies > Water Disinfectants > Level 2 > Question 3
Scientific Facts on
Water Disinfectants & disinfectant by-products
Previous Question
Level 1 Questions
Source document: IPCS (2000) Summary & Details: GreenFacts (2004)
More
Next Question
3. How can disinfectants and their by-products affect health? 3.1. Disinfectants themselves, at the concentrations used, do not appear to contribute to toxicity but it is the byproducts and breakdown products that have received attention. Chlorine gas, chloramine and chlorine dioxide are strong respiratory irritants, but only at much higher exposure than would result from the release of vapors through from drinking-water. More... 3.2. The different groups of chlorine by-products have different toxicity. They can particularly affect the liver and kidney of laboratory rats and mice: ●
●
●
● ●
The toxicity of the trihalomethanes (THMs) in laboratory animals is higher when administered with corn oil than with water. Chloroform is not considered to be genotoxic and induces cancers only at high doses after tissues have been damaged. The other THMs appear to be weakly genotoxic. At high doses, some induce tumours of the liver and kidney and others of the large intestine, when administered in corn oil. The haloacetic acids (HAAs) produce a range of effects in rodents including tumours of the liver and reproductive and neurological effects, but only at very high doses. They are only weakly genotoxic but this does not appear to be how they cause tumours. Chloral hydrate has been shown to potentially induce liver tumours and other health effects in laboratory rodents but only at very high doses. Some of the other halogenated aldehydes and ketones are highly genotoxic possibly carcinogenic and one, chloroacetaldehyde has induced liver tumours in laboratory animals. The haloacetonitriles have not been well studied. Some are mutagenic, but may not induce tumours. MX is a very potent mutagen in bacteria and also appears to cause some tumours in laboratory rats. More...
3.3. The by-products of chlorine dioxide, chlorite and chlorate, can damage red blood cells. Chlorite may cause mild neurobehavioural effects in rat pups at relatively high doses but does not increase tumours in laboratory animals. Chlorate shows lower toxicity than chlorite. More... 3.4. Bromate, the main by-product of ozonation, has been shown to induce tumours of the kidney, peritoneum and thyroid in rodents at high doses. More...
Back to Summary
Level 2 Questions
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-3.htm (1 of 2) [24/09/2004 10:07:25]
More in the Source Document
Water Disinfectants : 3. How can disinfectants and their by-products affect health? Previous question
Send this page 23-Sep-2004
Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-3.htm (2 of 2) [24/09/2004 10:07:25]
Next question
Download this study Top
Water Disinfectants : 4. Have disinfectants and their by-products affected human health?
Home > Studies > Water Disinfectants > Level 2 > Question 4
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Previous Question
Level 1 Questions
More
Next Question
4. Have disinfectants and their by-products affected human health? 4.1. Has water disinfection caused cardiovascular disease or cancer? 4.2. Has water disinfection harmed pregnancies?
4.1. Has water disinfection caused cardiovascular disease or cancer? There are no indications that chlorinated or chloraminated drinking-water are a cause of cardiovascular disease in humans. Studies on other disinfectants have not been performed. Many epidemiological studies have been carried out on the possibility that chlorinated drinking water, and to a lesser extent chloramination, could contribute to cancer in human populations. There have been weak indications that the consumption of chlorinated drinking water may have increased the number of cancers of the bladder, rectum and colon in some studies. However, because the exposure to water contaminants was generally not adequately evaluated, there is no sufficient evidence to say that chlorinated drinking water was or was not the cause of these cancers. It is possible that the associations observed might be due to some other factors. There are no epidemiological studies on the carcinogenic effects of other disinfectants. More...
Back to Summary
Level 2 Questions
More in the Source Document
Top
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-4.htm (1 of 2) [24/09/2004 10:07:28]
Water Disinfectants : 4. Have disinfectants and their by-products affected human health?
4.2. Has water disinfection harmed pregnancies? Some studies of populations having consumed chlorinated water, have found small to moderate increased risks for some adverse birth outcomes such as miscarriage and neural tube defects. However, these studies are difficult to interpret because of methodological limitations or suspected bias and they need to be confirmed by other studies. The experts concluded that the results of currently published studies do not provide convincing evidence that chlorinated water or THMs cause adverse pregnancy outcomes. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-4.htm (2 of 2) [24/09/2004 10:07:28]
More in the Source Document Next Question
Download this study Top
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
Home > Studies > Water Disinfectants > Level 2 > Question 5
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants & disinfectant by-products
Previous Question
Level 1 Questions
Summary & Details: GreenFacts (2004)
More
Conclusions
5. What are the risks posed by disinfectants and their by-products? 5.1. 5.2. 5.3. 5.4.
What tolerable daily intakes and guideline values has the WHO set? How much disinfectants and by-products are we exposed to? Are there uncertainties in assessing exposure? Have epidemiological studies been able to evaluate the risks?
5.1. What tolerable daily intakes and guideline values has the WHO set? For disinfectants and disinfectant by-products (DBPs) with sufficient data, the World Health Organisation (WHO) has set safe acceptable intake levels. These levels are called Tolerable Daily Intakes (TDIs). TDIs are determined by taking the level at which no harmful health effect has been observed (No Observed Adverse Effect Level or NOAEL) in a particular animal species (e.g. mice, rats, hamsters) and applying an uncertainty factor (in this case, between 100 and 1000 depending on studies available and confidence in the results). These TDIs are used as a basis for developing the WHO drinking water guidelines that are, in turn, used by many countries, including the European Union (EU), as a basis for their drinking water standards. The guideline values are typically derived from the TDI assuming the average adult weighs 60 kg and drinks 2 litres of water per day. The following tables present TDIs for disinfectants and disinfectant by-products and the NOAELs from which they were derived. In addition to the data from the IPCS report, presented in the first two columns, a third column is added, which is based on the "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004, providing the most up-to-date guideline values in terms of concentrations in drinking water. 5.1.1. Disinfectants (More...) Table 1. Intake reference values for disinfectants NOAEL (µg/kg body weight) Chlorine
15 000
Tolerable Daily Intake (TDI) WHO drinking water guideline ( µg/kg body weight) value (µg/litre)* 150
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (1 of 6) [24/09/2004 10:07:31]
5 000
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
Monochloramine Chlorine dioxide (1) (based on chlorite)
9 400
94
3 000
2 900 (chlorite)
30
700 (chlorite)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004
5.1.2. Chlorine by-products (More...) Table 2. Intake reference values for chlorine by-products NOAEL (µg/kg body weight)
Tolerable Daily Intake (TDI) WHO drinking water guideline (µg/kg body weight) value (µg/litre)*
Trihalomethanes
(1 )
-BDCM
-
-
60 (2)
-DBCM
30 000
30
100
-Bromoform
25 000
25
100
-Chloroform
10 000
10
200
Haloacetic acids
(3 )
-DCA
40 000
40
50
-TCA
40 000
40
200
160 000
16
10 (4)
Chloral hydrate Haloacetonitriles
(5 )
-DCAN
15 000
15
20
-DBAN
23 000
23
70
MX
Not established (6)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004
5.1.3. Chlorine dioxide by-products Table 3. Intake reference values for chlorine dioxide by-products
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (2 of 6) [24/09/2004 10:07:31]
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
NOAEL (µg/kg body weight)
Tolerable Daily Intake (TDI) WHO drinking water guideline (µg/kg body weight) value (µg/litre)*
Chlorite
2 900
30
700
(1)
Chlorate
30 000
30
700
(1)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004
Notes referring to the above table 1: The Tolerable Daily Intake (TDI) for chlorite and for chlorate has translated into a WHO provisional drinking water guideline value. The TDI reflects current lack of a specific long-term study which is in progress. More... 5.1.4. Ozonation by-products (More...) Table 4. Intake reference values for ozonation by-products NOAEL (µg/kg body weight) Bromate
Tolerable Daily Intake (TDI) WHO drinking water guideline (µg/kg body weight) value (µg/litre)*
1 300
1
10
(1)
* Source: "Third edition of the WHO Guidelines for Drinking-Water Quality" 2004 Notes referring to the above table 1: At present there are conflicting data regarding the exact mechanism by which bromate causes cancer in laboratory animals and how that would impact on risk assessment. The WHO has developed a drinking water guideline value of 10 µg/litre based on two approaches and taking into account the practicality of using ozone. Where bromide is present in the raw water, the guideline value can only be achieved by appropriate control of disinfection conditions.
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (3 of 6) [24/09/2004 10:07:31]
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
5.2. How much disinfectants and by-products are we exposed to? Typically, several milligrams of disinfectant per litre (mg/l) of water are employed in the system, corresponding to the dose necessary to kill the microorganisms in the treatment plant (primary disinfection) and the dose necessary to maintain a residual disinfection in the distribution system (secondary disinfection). The concentration at the tap is considerably less than initially injected. The concentrations of disinfection by-products will vary according to the raw water quality and its physical and chemical properties such as pH and temperature, and the level of drink-water treatment. Chlorine by-products:
●
●
●
Trihalomethanes (THMs) are normally dominated by chloroform but the levels of brominated THMs will depend on the bromide present in the water. The concentration of total haloacetic acids (HAA) is generally about half of the total THMs but it is quite difficult to generalize. Dichloroacetic acid (DCA) and trichloroacetic acid (TCA) are the first and second most dominant species. If a hypochlorite solution is used instead of chlorine gas, chlorate may also occur during chlorination.
When the disinfectant is chloramine, the by-products depend on the mode of chloramination, application of ammonia followed by chlorine leading to lower levels of chlorine by-products. Bromate is primarily formed by ozonation of water containing bromide: about 50% of the bromide is converted to bromate. In European water treatment plants, the concentration of bromate was found to be a maximum of 16 mg per litre. When the disinfectant is chlorine dioxide, about 50 to 70% of the applied dose forms chlorite. More...
Back to Summary
Level 2 Questions
Next Sub-Question
More in the Source Document
Top
5.3. Are there uncertainties in assessing exposure? Toxicological studies attempt to extrapolate the results of laboratory animal studies to humans. This may lead to an estimation of risk factors for some health effects. Epidemiological studies attempt to link human health effects (e.g. cancer) to a cause (e.g. exposure to a disinfectant by-product, DBP) and require exposure assessments. Humans can be exposed to chemical risks from disinfected drinking-water through several routes:
● ●
●
ingestion of disinfectant by-products (DBPs) in drinking-water; ingestion of drinking-water that has a residual of free chlorine at the tap and the resulting formation of DBPs in the mouth and stomach (ozone cannot be present at the tap and chloramines and chlorine dioxide do not react to form by-products); inhalation of volatile DBPs during showering.
However, it is generally assumed that the most significant route is the ingestion of DBPs. Human health effects depend on both DBP concentration and duration of exposure. They are difficult to assess
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (4 of 6) [24/09/2004 10:07:31]
Water Disinfectants : 5. What are the risks posed by disinfectants and their by-products?
because DBP mixtures: ●
●
●
are complex, e.g. trihalomethanes (THMs) versus haloacetic acids (HAAs), chlorinated versus brominated species ; change with time, as a function of temperature, nature and concentration of natural organic matters (NOM) in the source water ; change with location, i.e. throughout a distribution system.
For epidemiological studies, some historical databases exist for disinfectant doses (e.g. chlorine) and possibly for DBP precursors (e.g. total organic carbon, TOC) and THM concentrations. In contrast, data for HAAs, bromate and chlorite are much more recent and hence sparse. When DBP data is not available, exposure can be estimated indirectly from the chlorine dose and other data. More...
Back to Summary
Level 2 Questions
More in the Source Document
Top
5.4. Have epidemiological studies been able to evaluate the risks? 5.4.1. Epidemiological studies are a very valuable tool in determining the possible risks from exposure to environmental chemicals. However, there are limitations to the use of Epidemiological studies because it is generally difficult to measure individual exposure to the chemical accurately and because there are usually other causes of the effect of interest, such as smoking or diet. This is also true for epidemiological studies of disinfectant by-products (DBPs). There is often no information on individual water consumption and generally very little information on the concentrations of DBPs other than trihalomethanes (THMs). Another important point for epidemiology is the consistency of the results between different studies. There have been more studies looking at bladder cancer than any other cancer but the evidence is not consistent. Some studies show an increased risk while others do not. In those that do show an increased risk, there are differences in the risk reported and between the sexes and smokers and non-smokers. More... 5.4.2. The epidemiological studies available provide insufficient evidence to establish that water disinfectants and their by-products cause any of the observed effects, mainly because of incomplete information about exposures to specific water contaminants. Risks may be due to other water contaminants or to other factors not taken into consideration. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-5.htm (5 of 6) [24/09/2004 10:07:31]
More in the Source Document Conclusions
Download this study Top
Water Disinfectants : 6. Conclusions
Home > Studies > Water Disinfectants > Level 2 > Question 6
Scientific Facts on
Water Disinfectants & disinfectant by-products
Previous Question
Source document: IPCS (2000) Summary & Details: GreenFacts (2004)
More
Level 1 Questions
6. Conclusions Disinfection is, without question, one of the most important barriers to waterborne disease in most parts of the world. As a consequence disinfection should never be compromised in attempting to control disinfection by-products. The risks of illness and death from germs in drinking water is very much greater than the risks from disinfectants and disinfection by-products. However, actions have been taken to reduce the levels of DBPs. Chlorine and alternative chemical disinfectants (ozone, chlorine dioxide and chloramine) all lead to the formation of disinfectant by-products (DBPs). Currently, the DBPs of most concern include trihalomethanes (THMs), haloacetic acids (HAAs), bromate and chlorite. The toxicology of the DBPs suggests that the likelihood of adverse effects is not significantly different between different disinfection options. Animal studies indicate that none of the chlorination by-products studied to date is a potent carcinogen at concentrations normally found in drinking water. There is insufficient epidemiological evidence to conclude that drinking chlorinated water causes cancers. The results of currently published studies do not provide convincing evidence that chlorinated water or THMs cause adverse pregnancy outcomes. Nevertheless it is prudent to take steps to minimise exposure to DBPs, where this can be achieved without compromising disinfection. Strategies should focus on eliminating organic impurities fostering DBP formation. More...
Back to Summary Previous Question
Send this page 23-Sep-2004
Level 2 Questions
More in the Source Document
Level 1 Questions
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/l-2/water-disinfectants-99.htm (1 of 2) [24/09/2004 10:07:36]
Download this study Top
GreenFacts: Factual Water Disinfectant Links
Home > Studies > Water Disinfectants > Links
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants
Summary & Details: GreenFacts (2004)
& disinfectant by-products
Create a link to our Water Disinfectant study
Water Disinfectant Links Factual Water Disinfectant Links - endorsed by the
GreenFacts Scientific Board
Some of the websites providing reliable scientific information on water disinfectants: Some Q&As & FAQs on water disinfectants More Info for the non-specialist Some water disinfectant News Sites Policy related websites
1. 2. 3. 4.
Other Links - not necessarily endorsed by the GreenFacts Scientific Board ● ●
Other Views suggesting that Water Disinfectants pose either more or less risks Sites linking to this study
Create a link to our Water Disinfectant study
http://www.greenfacts.org/water-disinfectants/links/index.htm (1 of 4) [24/09/2004 10:07:41]
Top
More
GreenFacts: Factual Water Disinfectant Links
1. Some Water Disinfectants Q&As & FAQs ●
●
●
●
The UK Drinking Water Inspectorate (DWI) discusses chlorine water disinfection at: http://www.dwi.gov.uk/consumer/faq/chlorine.htm (2002). The San Francisco Public Utilities Commission (SFPUC) answers questions about water disinfectants at: http://sfwater.org/detail.cfm/MC_ID/10/MSC_ID/51/MTO_ID/NULL/C_ID /654#trihalomethanes The City of Ottawa in Canada also answers questions relating to chloramine disinfection at: http://www.city.ottawa.on.ca/city_services/water/27_2_5_2_1_en.shtml (2004). ToxFAQs by the American Toxic Substances and Disease Registry (ATSDR): http://www.atsdr.cdc.gov/toxfaq.html addressing the following water disinfectants: chlorine, chlorine dioxide and chlorite,bromoform & chlorodibromomethane and chloroform (1997-2002).
Create a link to our Water Disinfectant study
Top
2. Some More Information for the Non-specialist ●
●
●
●
●
●
●
The International Water Association (IWA) explains the practice of chlorination at: http://www.iwahq.org.uk//template.cfm?name=bp0004 The National Toxicology Program's factsheet of it Safe Drinking Water Program at the US National Institute of Environmental Health Science (NIEHS) is presented at: http://ntp-server.niehs.nih.gov/htdocs/liason/factsheets/DrinkingWaterFacts.html (2002). The Aquastel group provides a table with the properties of several water disinfectants at: http://www.aquastel.com/comparison.shtml An index to drinking water facts by the Australia's Cooperative Research Centre for Water Quality and Treatment (CRC) is presented at: http://www.waterquality.crc.org.au/aboutdw_dwfacts.htm, including documents on water treatment and water safety. Information on pre-treatment and chemical water treatment from the World Health Organization (WHO) is presented at: http://www.who.int/water_sanitation_health/dwq/wsh0207/en/index6.html (2004). The US Centre for Disease Control (CDC) discusses variety of conclusions at: http://www.cdc.gov/safewater/thm.htm The Chlorine Chemistry Council (CCC) provides information on water disinfection at: http://c3.org/chlorine_knowledge_center/index.html#3
http://www.greenfacts.org/water-disinfectants/links/index.htm (2 of 4) [24/09/2004 10:07:41]
GreenFacts: Factual Water Disinfectant Links Create a link to our Water Disinfectant study
Top
3. Some Water Disinfectants News Sites ●
●
●
●
The US Water Quality and Health Council (WQHC) has drinking water news at: http://www.waterandhealth.org/drinkingwater/ Recent news on water quality provided by the Water Environment Federation (WEF) at: http://www.wef.org/WaterNews/ The American Water Works Association (AWWA) "Waterweek" news at: http://www.awwa.org/communications/waterweek/ The US Environmental Protection Agency (EPA) general drinking water information can be accessed through their Ground Water & Drinking Water website: http://www.epa.gov/safewater/
Create a link to our Water Disinfectant study
Top
4. Some Policy-related Websites ●
●
The WHO Guidelines for drinking water quality are presented at: http://www.who.int/docstore/water_sanitation_health/GDWQ/Updating/ draftguidel/draftchap87c.htm#8.7.4 The US Environmental Protection Agency (EPA) presents its policy at: http://www.epa.gov/ebtpages/watewaterdisinfectionbyproducts.html The US EPA is currently drawing up new regulations regarding DBPs. These developments can be followed from: http://www.epa.gov/safewater/mdbp.html
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/links/index.htm (3 of 4) [24/09/2004 10:07:41]
Download this study Top
GreenFacts : About this study on Water Disinfectants
Home > Studies > Water Disinfectants > About this study
Scientific Facts on
Source document: IPCS (2000)
Water Disinfectants & disinfectant by-products
Summary & Details: GreenFacts (2004)
More
GreenFacts Copyright Policy
About this Water Disinfectant study 1. Sources for this Study 2. Current Status 3. Study Publication History
1. Sources for this Study The material content of the texts on Level 3 are directly sourced from the Executive Summary of the Environmental Health Criteria (EHC) 216: disinfectants and disinfectant by-products, a leading scientific report produced in 2000 by a large international panel of scientists of the IPCS (International Programme on Chemical Safety). The Levels 1 & 2 were written by Dr. John Fawell in collaboration with the
GreenFacts team.
More on the Source and Copyright
2. Current Status Second draft completed and preliminary review on-going.
3. Study Publication History The GreenFacts publication process is designed to ensure as high a degree of objectivity as possible.
First draft The first draft of this study was produced by Dr. John Fawell on November 2003 on the basis of a canvas prepared by the GreenFacts team.
http://www.greenfacts.org/water-disinfectants/about-water-disinfectants.htm (1 of 3) [24/09/2004 10:07:46]
GreenFacts : About this study on Water Disinfectants
Second draft The second draft of this study has been produced in February 2004 by Dr. John Fawell after review by the GreenFacts team.
Preliminary review The final draft of this study will be produced in early 2004 by Dr. John Fawell after pre-review by experts from environmental and industrial organizations (see our pre review form).
Peer review The final draft will be peer reviewed by 3 independent scientists selected by the GreenFacts Scientific Board (see peer review form) and final corrections will be added under the supervision of the GreenFacts Scientific Board
our
in early 2004.
Publication Final publication will be authorized by the President of the GreenFacts Scientific Board in early 2004.
Updates or subsequent post-publication revisions No update or revision at present. GreenFacts Copyright Policy
Send this page 23-Sep-2004
Subscribe to our newsletter Contact | Copyright | Glossary | Sitemap | Link to us | Feedback | About GreenFacts® is a registered trademark of GreenFacts asbl
http://www.greenfacts.org/water-disinfectants/about-water-disinfectants.htm (2 of 3) [24/09/2004 10:07:46]
Download this study Top
IPCS
About the Toolbox | Back | Print | Forward
International Programme on Chemical Safety IPCS Home page |
About IPCS
The International Programme on Chemical Safety (IPCS) was established in 1980 by the WHO, the UNEP and the ILO (International Labour Organisation) "for the early warning and prevention of harmful effects of chemicals to which humans were being increasingly exposed, and for the assessment of the potential risks to human health." It has collaborated to and published many highly recognized scientific publication. Most publications are availaible from the INCHEM website www.inchem.org, "a means of rapid access to internationally peer reviewed information on chemicals commonly used throughout the world, which may also occur as contaminants in the environment and food." Publications include: ●
●
About 250 "Environment Health Criteria" monographs (EHCs), available at www.inchem.org/pages/ehc.html About 50 "Concise International Chemical Assessment Document" (CICADs), available at www.inchem.org/pages/cicads.html
IPCS publications not published on the INCHEM website are posted at IPCS Home page |
www.who.int/pcs/
About IPCS
Back | Print | Forward 05-Aug-2004
http://www.greenfacts.org/links/site-boxes/ipcs.htm (1 of 2) [24/09/2004 10:07:55]
Top
Related Documents
Water Disinfectants Green Facts
November 2019 23
Cool Green Facts
May 2020 11
Climate Change Green Facts
November 2019 19
Green Carts_get The Facts
May 2020 9
Ecosystem Green Facts
November 2019 21
Ecosystem Green Facts
November 2019 26More Documents from "Daisy"
Pm - Cross Cultural Communications Part 5
November 2019 28
Emperor's New Crops
November 2019 13
Assessing Energy Futures 3
November 2019 30
Oteshauk Handbook
May 2020 9
Cultural Heritage E01
November 2019 17