• July 2020
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Preventive medicine-means accepting the ultimate responsibility for our own health. .. Preventive medicine is that part of medicine engaged with preventing disease rather than curing it. It can be contrasted not only with curative medicine, but also with public health methods (which work at the level of population health rather than individual health). What is three level prevention?  Primary prevention (pathogeny prevention)  Secondary prevention (three forepart prevention)  Tertiary prevention (clinical prevention) Ultimate goals of health protection  Healthy People in Every Stage of Life  Healthy People in Healthy Places  People Prepared for Emerging Health threats  Healthy People in a Healthy World Ecosystem- A functional system which constituted by biome and its living surroundings. The substance, energy, information are transferred in ecosystem. Food chain- All living things depend on each other to live. The food chain shows how some animals eat other animals to survive. While being food for animals higher in the food chain, these animals may eat other animals or plants to survive. The food chain is a complex balance of life Bioconcentration- When a chemical becomes absorbed and concentrated in specific organs or tissues, the concentration of the chemical in the organism is higher than that in the environment. Biomagnification- The level of some chemical or toxins in the environment are magnified as they pass through the food web, so the toxins’ concentration in high trophic level organism is higher than that in low trophic level organism. The relationship between human and environment-

• Substance oneness of human beings and environment • Adaptability of human beings to environment • Human beings can change the world on one's own initiative, environment will feed back human beings. environmental pollution-Pollutant produced by human being’s activity, pour into environment and exceed the environment capacity, devastate ecological balance, influence human body directly or indirectly. This phenomenon called environment pollution. The characters of environmental pollution  Fargoing  Low concentration  Long-term  Multifactor  Those effect associate with each other, with a lot of means. 4 step risk assessment process  Hazard Identification-identify health risks associated with exposure  Dose-Response Assessment-model the relationship between dose and effects  Exposure Assessment-estimate a group’s exposure (amount, duration)  Risk Characterization-estimate the probability and severity of effect Water pollution- When pollutants are poured into the river, the lake and so on, leading to the result that the physical and chemical nature of the water quality has been changed, reduces the use-value of the water quality and do harm to the human being’s health or destroy the balance of the ecological system. Impairment of water for its intended use, actual or potential, by man-caused changes in the quality of water  May be a natural substance  May be a toxic synthetic compound

BOD- The amount of oxygen consumed by bacteria to break down the organic matter present in a water sample. COD- The COD test is a chemical approximation of the BOD test. Oxygen consumed by chemicals in reactions in a water sample. Using oxidant oxidize 1L water under a welldefined conditions and then detecting the value of consumed DO. Standard of our country sets COD should not exceed 2-3mg/L. DO- The amount of oxygen dissolved in water. An indicator of oxygen content in water measured in mg / L. Eutrophication- Usually occurs in streams, lakes and ocean, being the accelerated growth of aquatic plants, often as a result of excessive inflows of nitrogen and phosphorus from agriculture, sewage treatment plants, and so on. Water borne disease- Diseases caused by ingestion of water contaminated by human or animal excrement, which contain pathogenic microorganisms such as cholera, typhoid, amoebic and bacillary dysentery and other diarrhea diseases. Advantages and disadvantages of surface water-- Softer  Reliable source  Quality is unstable  Has two flow periods  low flow period (period without rainfall)  high flow period (period with rainfall). Advantages and disadvantages of ground water-- Advantages  Clear, cool, colorless  Uniform in character  Better bacterial quality  Less organic material  Easy to protect  Disadvantages  High minerals

 Quantity hard to find out Class of water pollution-There are three classes of water pollution. They are— 1- physical 2- chemical 3- biological Types of water pollution- There are 2 types of water pollution. 1- point source pollution 2- non point source pollution Typicall pollutants within 3 classes1- Physical - General conditions such as temperature, flow, water color, and the condition of stream banks and lake shores are also important. 2- Chemical - Such as organic constituents (insecticides, herbicides, and industrial organic compounds). 3- Biological - The abundance and variety of aquatic plant and animal life and the ability of test organisms to survive in sample water are also widely used to monitor water conditions. Epidemiological characters of water-borne disease--① it is fulminant, many diseases take place between in the shortest and longest latent period. ②The distribution of the case accords with the distribution of the water supply. ③Once the steps have been taken to control, the pollution and the purification and disinfecting of the water has been reinforced, the epidemic will be controlled quickly. Cause of minimata disease---- Minamata disease is the chronic poisoning disease caused by CH3Hg+. Causes of itai-itai disease------ "itai-itai disease is chronic cadmium poisoning. It first impairs kidney function and progressively causes osteomalacia and osteoporosis Total bacteria count---- It means the total bacteria in 1 ml water sample which has been cultured in common nutritious agar medium for 24 hours under 37℃.

It can be used to judge the cleaning effect of the water purification. Total coliform group---- Total coliform counts in 1ml water sample. The standard regulates that the total coliform group will be 0 CFU/L. While their presence may not signify that a water is a health hazard, their absence provides reasonable evidence of bacteriological safe water. Free residual chlorine---- After the course of disinfecting, many bacteria has been killed, keeping certain concentration of free residual chlorine can make the disinfecting effect steady and lasting. It should be 0.3~0.5mg/L in the drinking water. General sanitary demands for drinking water quality----• Security in the epidemiology. • The chemical components should do no harm to the body and should do benefit to the body. • The sensory nature of the water should be good. • The quantity of water should be enough, and it should be used conveniently. Proper procedures for water treatment---- Pretreatment  Alum  Carbon  Sedimentation  Filtration  Disinfection  Chlorine  UV  Storage  Distribution Mechanism of chlorination----When chlorine is added to water, it is hydrolized immediately and completely, according to the following reaction Cl2 + H2O = HOCl + H+ + ClHypochlorous acid is neutral molecule and it can penetrate through the cell wall easily.

It is also an oxidant. It can damage the cell membrane and make DNA, RNA and protein released and so lead to the bacteria death. Majot symptoms of endemic fluorosis…..  Dental Fluorosis  Skeletal Fluorosis Major causes of epidemic fluorosis---- Excessive fluorides in drinking water supplies are the most common reason.  Excessive fluorides in coal that leads to food and air polluted. Epidemiological character of endemic fluorosis…  This disease occurs mainly in droughty and some mountain areas.  The concentration of fluoride is very high in the drinking water or polluted air. Preventive measures of endemic fluorosis…. • Change the source of water • Defluoride of drinking water • Change the type of coal and the way of food preservation

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