Mercury pollution from coal burning or mining has recently fallen significantly. But tuna is still almost as contaminated with the toxic heavy metal as it was in the early 1970s.
Mercury is difficult to excrete and accumulates in predatory fish such as tuna. Pregnant women are advised not to eat tuna. Infants and small children are also particularly at risk from neurotoxic effects because their development is not yet complete and their nervous tissue is therefore vulnerable. The Federal Environment Agency in Germany says mercury pollution is harmless to health.