EVISA Newsletter

Mercury is a very toxic element and some of the organic mercury compounds are even more toxic for humans. It is very likely that the mercury concentration in the earth atmosphere was much higher during earths early history due to volcanic activity. The role of biology is also critical in understanding the environmental cycling of the element. Although mercury is rarely directly involved in biological processes-except in some rare bacteria-its interactions with oxygen came about entirely due to the appearance of the photosynthetic process, which plants and certain bacteria use to convert sunlight into chemical energy. Mercury also has a strong affinity for carbon-based compounds that come from biological material, such as coal, shale, petroleum, and natural gas products. By the formation of mercury minerals (see: R.M. Hazen et al., Am. Mineral., 97 (2012) 1013-1042. DOI: 10.2138/am.2012.3922) the toxic element was fixed to the earth crust and atmospheric concentration reduced. Unfortunately, now it is man how brings it back to the biosphere by mining, burning all the fossil fuels, roasting the minerals (e.g. in cement kilns) or combusting waste and other materials. While early organisms (e.g. bacteria) were quite resistant to this toxic element, today's organisms are much more sensitive.

Human activities have raised the mercury level during the last centuries and bacterial activity is heavily involved in the cycling of the element. A group of scientists in Sweden has now investigated, how climate change would influence such cycling. Their results are quite scary: Efforts to reduce mercury emissions may be offset by the impacts of climate change, including increased precipitation and runoff, and we might not see an expected decrease of methylmercury in the food web. (see the News below)

Human health organizations such as WHO, CDC etc. therefore regularly warn especially pregnant woman to limit the consumption of contaminated seafood in order not to harm the developing child. The UNEP Minamata Convention tries to limit the industrial use and emission of the element to the environment, in order to reduce human health risks. Interestingly, pharmaceuticals were exclude from the mercury ban, so that mercury laden vaccines can be injected into mothers and their babies, while the mother is carefully limiting dietary exposure. This astonishing situation was explained by CDC, WHO and other "health" organizations with the message that the mercury in vaccines (Thimerosal and the released ethylmercury) is totally different from the methylmercury in seafood. Two CDC scientists now have reviewed the vast literature on mercury toxicity and conclude that different organomercury compounds share the same fundamental mechanisms related to their toxicity: there is no harmless mercury, both methylmercury and ethylmercury are extremely toxic. (see the news below)