Mercury levels along the food chain and risk for exposed populations.

Mercury was not regarded as a pollutant of primary importance until many deaths due to mercury poisoning occurred in the 1950s. More recently, adverse health effects have been documented at relatively low exposure levels, and monitoring data must now be interpreted in this light. The Mediterranean basin has been studied in great detail over the past 20 years because of the anomalous natural presence of mercury. Marine animals of this basin have higher mercury body burdens than the same (or similar) species in the Atlantic. The mercury found in marine organisms is mainly in the form of methyl mercury. Long-term and frequent intake of seafood with high mercury levels by populations living in coastal fishing villages is associated with a toxic risk, especially in pregnant women. High blood and hair concentrations of mercury have repeatedly been found in fishermen of Tyrrhenian coastal villages. In some cases these concentrations have been associated with an increase in DNA damage in blood cells. High mercury levels in hair and blood of people from a fishing village of Madeira have also been found. This information deserves renewed scrutiny with regard to preventive efforts needed.