Human and environmental contamination by mercury from industrial uses in Brazil

The amount of Hg used for industrial purposes in Brazil has been estimated as 105 t.yr(-1), of which 50% is released into the environment. As the industries that use this Hg are located in the neighborood of highly populated areas. the number of people exposed td the risk of contamination is high. Severe cases of chronically poisoned workers hale been reported most of them presenting neuropsychological disorders. Contamination of air, soil and water resources are also observed. Analysis of sediments, water and biota of Guanabara Bay, Rio de Janeiro, show contamination of all segments by Hg originating mainly from a chlor-alkali plant located nearby. Higher concentrations of Hg were found in the sediments (0.7 to 20 mg.kg(-1)) where it is associated with organic matter usually under anoxic conditions. Mercury can became bioavailable by organification or by changes in the actual environmental conditions and is thus an important source of environmental contamination of people who consume its biota.