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Water Health

A summary of the concerns related to water pollution.
Historically, the concern about water pollution was related to its health effects. While in many countries this remains true, in developed countries, the result of improved treatment and distribution methods have, to a certain degree, shifted the emphasis. The main sources of water pollution include both inorganic and organic wastes, heat from industries, petroleum compounds, municipal wastes, agricultural wastes, pesticides, and acid mine drainage. Many industrial processes have the potential of discharging different types of wastes that could cause significant water pollution problems. Human diseases and casualties arising from water pollution attracted worldwide attention after “Minamata disease” broke out in Japan during the 1950s.
Minamata disease was caused by eating fish and shellfish laden with highly toxic methylmercury, the organic form of mercury that bioaccumulates in aquatic food webs. Humans and wildlife are exposed to methylmercury primarily through the consumption of contaminated fish, particularly large predatory fish species such as tuna, swordfish, and shark. In humans, methylmercury is known to be neurotoxic, and, as it can pass the placental barrier, the fetus is more sensitive to those effects than the adult. In addition to heavy metals, a variety of inorganic and organic compounds can contaminate streams, lakes, and rivers, threatening their water quality. For example, stream water or garden fertilizers may be contaminated with perchlorate.
Industrial and military operations and firework manufacturers use perchlorate as an oxidizing agent, and they appear to be the primary sources of contamination. Perchlorate and perfluoroalkyls, (PFAs), are potentially harmful to thyroid function and could be widespread in some agricultural areas. Moreover, dioxins and polychlorobiphenyls (PCBs), may be released into waterways by the incineration of rubber and plastics and through the use of pesticides that contains added PCBs. Since such contaminants similar to mercury are highly lipophilic, they tend to accumulate in the adipose tissue of living animals. Humans are thus exposed through the consumption of animal products rich in fat, such as fish. Dioxins and PCBs responsible for chronic toxicity, characterized by endocrine disruption, impairment of the immune system, and increased tumor incidence.
Those pollutants, for the estrogenic activity, enabling them to interfere with the neuroendocrine system and its development, are called endocrine disruptors. They may also impair fertility and meat production of exposed animals. Among those, tributhyltin, (TBT), is an important issue for aquaculture. TBT is an antifungine which leaks in water from boat paint. It contaminates shellfish, then bioaccumulates through food chain as other lipophilic compounds. Disease outbreaks linked to the microbiological quality of water is also an important public health concern. These global challenges are threatening to reduce agricultural yields and further increase the contamination of various water sources, leading to the production of fresh produce contaminated with pathogenic microorganisms.
Water, an important raw material in fresh produce chain, is used in considerable amounts in many operations, including irrigation and application of pesticides and fertilizers, but also as an important transport medium for cooling and washing in post-harvest practices. In several reported outbreaks related to uncooked fruit and vegetable products, water has been identified as the likely source of the outbreak. There are two main sources of irrigation water, surface water or treated wastewater, more prone to contamination and variable in water quality. Ground water reserves, or collected rainfall water, less prone to contamination, or more controlled water if stored property.
Drip or subsurface irrigation limits direct contact between edible plant tissue and irrigation water, splashes, and thus is less likely to introduce pathogens than furrow or sprinkler irrigation. Codes of practice stress the importance of the quality of the irrigation water source for ensuring safety of fresh produce. A few general principles of preventive measures are regular execution of and response to sanitary surveys, maintenance of irrigation water reservoirs and distribution systems, adequate water treatments to gain better water quality, fecal indicator tests to monitor water quality.

The main sources of water pollution include both inorganic and organic wastes, heat from industries, petroleum compounds, urban wastes, agricultural wastes, pesticides, and acid mine drainage. Among these pollutants mercury, perflouoroalkyls (PFAs e.g. perchlorate), tributyiltin, dioxins and polychlorobiphenyls (PCBs) are present.

Water pollution may affect health since many of them are highly lipophilic, and bioaccumulate along the food chain. Moreover, since water is an important raw material in the fresh produce chain, it may contaminate food through irrigation and application of pesticides and fertilizers, but also as a transport medium and for cooling and washing in postharvest practices.

For this reason it is essential to monitor water quality at each step in the food chain.

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