
Mercury
Mercury in the environment caused some concern a few years ago when it was found in fish as organic mercury. Organic mercury in the form of methyl mercury has been found to cause neurological problems with a daily intake of as little as 0.25 mg. Mercury is a cumulative poison and so low levels of organic mercury can build up in the body over a period of time. Fortunately, mercury in drinking water is predominantly inorganic, which is poorly absorbed by the body. Nevertheless, a very low limit for mercury is set.