Heavy Metal Contamination in Biotic Component: A gradual case study in West Bengal

Abstract

Fish is a popular human food. Over two-and-a-half billion people globally obtain their daily nutrient intake from fish. In India, it is a major dietary component for over 50 percent, and is a particularly important nutrition source for the poor. Mercury is a deadly environmental pollutant, both in its elemental form and in combination with other chemicals. When released into the environment mercury is transformed into methylmercury through microbial action. Methylmercury is the most pernicious form of mercury. It bioaccumulates in fish and enters human body with the consumption of contaminated fish. Fish in polluted water bodies accumulate methylmercury – a toxic pollutant of high potency that crosses the blood brain barrier and placental barrier, making it an intergenerational toxin. It enters the food chain both from point and non-point sources. Effluent pipes from industrial processes often contain mercury or mercury compounds. Emissions and ash from coal-fired power plants also contain mercury. It is well known that mercury circulates globally and deposits in water, bioaccumulating in the food chain through algae and fish. The higher the pecking order of a fish in the food chain, greater is the amount of mercury it is likely to contain. Advisories on fish consumption are quite common in developed countries, especially for pregnant women. Human exposure to such toxins therefore assumes significance. Contamination of this vital food is a key issue. In developing countries, issues like food contamination rarely draw attention. Mere availability of food is argued to be of foremost concern. In this scenario of poverty and hunger, system of industrial production has largely remained unaccountable to society and the environmental pollution it causes.