In the 1960s, extremely high mercury concentrations were measured in the tissues of the Saimaa ringed seals, which is suspected to have contributed to the rapid decline of the population. Even though industrial emissions have declined drastically during the last decades, silvicultural treatments and floods still release heavy metals from old deposits in soils. In addition to heavy metals, other chemicals that are easily transported in the atmosphere form a threat to the Saimaa ringed seal. These include, for example, polyfluorinated compounds (PFS) used in manufacturing of Teflon, and polybrominated compounds (PBDE) used as flame retardants. Ecotoxicological research aimed to determine the present concentrations of environmental contaminants in Saimaa ringed seals, and to assess the effects of the chemical load on their wellbeing.