compared to concentrations of classical contaminants like PCBs, several other studies in the Oslo Fjord in Norway, Lake Pepin in the US, and Lake Erie in Canada have shown concentrations of siloxanes decrease at higher range in the food chain. This finding raises questions about which factors influence the bioaccumulation potential of siloxanes." Cyclomethicones are ubiquitous because they are widely used in biomedical and cosmetic applications. They can be found at high levels in American cities. They can be toxic to aquatic animals in concentrations often found in the environment. The cyclomethicones D4 and D5 are bioaccumulative in some aquatic organisms, according to one report. In the European Union, D4, D5 and D6 have been deemed hazardous as per the REACH regulation. They were characterized as substances of very high concern (SVHC) due to their PBT and vPvB properties. Canada regulates D4 under a pollution prevention plan. A scientific review in Canada in 2011 concluded that "Siloxane D5 does not pose a danger to the environment." Literature Christoph Rücker, Klaus Kümmerer: Environmental Chemistry of Organosiloxanes. In: Chemical Reviews. 115(1), 2015, p. 466–524, . References External links EPA report: Siloxane D5 in Dry-cleaning Journal Of Protective Coatings And Linings: Field Performance of Polysiloxanes