How mercury impacts on the environment and humans
Mercury can cause severe damage to both health and the environment. Perhaps the most serious damage is that caused to the nervous system of humans during the foetal period and the consequent risk of impaired learning and development in children.
Studies have shown that such damage probably occurs even at extremely low concentrations of mercury.
Mercury is found everywhere around the world in both humans and animals. Bioaccumulation occurs in the food chain, with the result that predators at the top of the food chain have higher concentrations than animals further down the food chain.
Mercury has been identified in both animals and humans on Greenland and in other Arctic areas, underlining the fact that the problem is a global one, as there are no local Arctic sources of any significance, and that extensive air- and seaborne transportation must therefore take place.
In the presence of micro-organisms, metallic mercury is naturally converted to methylmercury, which can be bioaccumulated in the food chain (a process that is often used in text books as an example of the importance of microbial activity). The highest concentrations therefore exist in predatory fish, animals and birds high up in the food chain. Fish containing mercury in concentrations that could have harmful effects if consumed in large quantities have been identified in many places around the world.
Mercury also exists naturally in the environment. It is very difficult to determine the ratio between anthropogenic and natural sources precisely, but there is no doubt that most mercury originates from anthropogenic sources.