Water Pollution and Human Health: Impact on Health
1. waterborne infectious diseases
Pathogens can enter the water body with human and animal feces, sewage and other pollution, causing bacteria, viruses, parasites and other pollution, leading to the spread of waterborne infectious diseases. Some harmful substances, such as copper, zinc, nickel and cyanide. After entering the environment, it poisons the microbial community in the water, thus hindering the inorganic process of organic matter in the water, affecting the self-purification ability of the water body and deteriorating the sensory appearance of the water body. Water pollution can also change the population advantage of aquatic organisms and even make some aquatic organisms extinct.
2. Acute and chronic poisoning
When the harmful substances in drinking water exceed the allowable concentration, acute or chronic poisoning may occur after drinking. For example, if the cyanide content in water is too high, acute poisoning will occur after drinking, which is manifested as intracellular asphyxia. If the methanol content in water is too high, it will lead to blindness after drinking. However, environmental pollutants are often in a low concentration, which repeatedly acts on the human body for a long time, making the human body's resistance and general health low, and causing an increase in the incidence and mortality of chronic diseases. In addition, some environmental poisons will also accumulate in the body, causing chronic poisoning.
3. Mutagenesis, Carcinogenesis and Teratogenesis
The common mutagenic substances in water are chloromethane, monobromomethane, tribromomethane, 1, 2- dichloroethane, chlordane, acrylonitrile, benzo (a) pyrene, vinyl chloride, pyrene and tetrachloroethylene, while tetrachloroethylene, chloroform, chlordane, lindane, dieldrin, aldrin, carbon tetrachloride and benzo (a). For example, a survey in seven counties of new york shows that the existence of chlorinated organic compounds in drinking water will increase the mortality of gastrointestinal cancer and urinary tract cancer. A survey in the southwest coastal area of Taiwan Province Province found that there was a dose-response relationship between the incidence of local skin cancer and arsenic concentration in drinking water. In recent years, the research on the pollution of Songhua River in China has found that there are more than 260 kinds of organic pollutants in Songhua River, and the concentrated substances in river water have obvious mutagenicity. The malignant tumors in the gastrointestinal tract of Harbin residents who drink river water for a long time are significantly higher than those who drink groundwater. It is not difficult to see from the above examples that mutagenic and carcinogenic substances in water may increase the incidence and mortality of cancer in the population.
There are some teratogenic substances in the water, such as methyl mercury carbaryl, dichlorvos, aldrin, sodium pentachlorophenol, 2,4,5-T and so on. The teratogenic effects of these substances can be divided into two situations. First, the normal embryonic development process is disturbed by the pregnant mother, which makes the embryonic development abnormal and leads to congenital malformation, which is not hereditary. On the other hand, mutagenic substances in the environment directly act on germ cells, affecting reproductive function and pregnancy, such as infertility, abortion, stillbirth, teratoma or other types of birth defects. The latter is hereditary and can pass the mutant gene to the offspring cells.
4. Glomerular chemical diseases
When the concentration of elements in biological tissues is in the range of milligrams per kilogram and micrograms per milligram, it is called trace elements. Although there are few trace elements in human body, they are all components of human hormones, enzymes and vitamins. In some waters, biogeochemical diseases caused by too many or too few trace elements in the base species are called endemic diseases.
In addition to the above hazards of water pollution to human beings, heavy metal pollution has also attracted people's attention. Heavy metal pollution mainly refers to the environmental pollution caused by mercury, cadmium, zinc, copper, nickel and cobalt. Mercury is the most toxic, followed by cadmium, and lead and chromium are also quite toxic.
Present situation of water pollution
The increasingly serious water pollution poses a great threat to the survival and safety of human beings and becomes the main obstacle to the sustainable development of human health, economy and society. According to the investigation of international authoritative organizations, 8% of all kinds of diseases in developing countries are spread by drinking unsanitary water. According to the latest survey report released by international charities, at present, 900 million people in the world do not have access to clean drinking water, 2.5 billion people do not have access to toilets, and as many as 5,000 children die every day due to poor sanitary conditions of drinking water, and at least 20 million people worldwide die every year. Therefore, water pollution is called. The world's number one killer? .
China is a country short of water resources, with per capita water resources less than 2,200m3, which is only 1/4 of the world average. It is one of the countries with the least water resources per capita in the world. However, rivers and lakes in China are sewers where factories dump toxic wastewater, causing water pollution incidents. Since the serious benzene pollution incident in Songhua River in 2005, there have been more than 40 water pollution accidents * * in China, and an average water pollution accident occurred in two to three days. For example, Chifeng water pollution incident, Shaanxi Fengxiang lead poisoning, Yangzonghai arsenic pollution, Guangxi Yongfu County water pollution caused a large number of fish deaths, Fuzhou ecological stream pollution? There have been many serious water pollution accidents in Huangshuigou, Ya 'an, Sichuan, and the blue-green algae incident in Taihu Lake.
At present, China is the country with the largest sewage discharge in the world, reaching more than 50 billion tons every year. A recent survey shows that the polluted area of the Yangtze River, the largest river in China, is constantly expanding, and 60% of the main stream of the Yangtze River has been polluted. The pollution of the Yellow River, the mother river of China, is also increasing, and nearly 40% of its main stream has basically lost its water function. The wastewater discharge in the Pearl River Delta is more prominent, with the Pearl River Delta with Guangzhou as the center accounting for more than 60% of the total. Pearl River pollution has caused serious water shortage along the Yangtze River and serious deterioration of the ecological environment. The Pearl River Estuary has become the largest port in South China and the second largest polluted port in China. Huaihe River is the river with the largest investment and the earliest pollution control in China, and it is still the most polluted river at present.
Harm of water pollution to other aspects of human beings
(1) Harm to Agriculture and Fisheries
Direct irrigation of farmland with sewage containing toxic and harmful substances will pollute farmland soil, reduce soil fertility, destroy the original good structure of soil, and lead to crop yield reduction or even no harvest. Especially in arid and semi-arid areas, the introduction of sewage irrigation may increase crop yield in a short time, but harmful substances such as heavy metals often accumulate in food crops and vegetables and endanger people's health through the food chain.
The quality of water environment directly affects fishery production. Fish and other aquatic organisms in natural water bodies are reduced or even extinct due to water pollution; Due to water pollution, freshwater fishing grounds and mariculture have also reduced fish production.
(2) Damage to industry
Many industrial products need water for processing. The deterioration of water quality not only directly affects the quality of products, but also causes problems such as blockage, corrosion and scaling of cooling water circulation system. The increase of hardness of industrial water will affect the service life and safety of boilers.