Mercury electrolysis in the Usoliekhimprom Co. was functioning from 1973 to 1998. In the mid 1990s it discharged 2.5 tons of mercury monthly with its wastewater, or 870 tons for the whole period of its operations. In 1998, mercury production at Khimprom was mostly stopped. Approximately one ton of mercury is still recovered from industrial waste per month. According to preliminary research, just under the buildings more than 500t of mercury has accumulated. A whole lake of mercury was formed under the soil. Studies of samples of tissues of fish and birds, mushrooms and local agricultural products revealed levels of mercury several times higher than relevant maximum allowable concentrations. Mercury levels in children's hair exceeded the regional background level by 8.7 times, and high levels of mercury were found in the urine of local residents.