Perfluorooctane sulfonate in the environment: chapter 8
The levels of PFOS were generally higher in urban and industrialized locations across Canada than in rural and remote locations. Consistent with other studies, these data indicate that human activities such as the use and disposal of consumer products containing PFOS and discharge to wastewater continue to be sources of PFOS to the environment. Other sources may include airports, where use of aqueous film-forming foam is permitted until May 2013, as well as other fire training areas where legacy contamination may be a continuing source to surface water. Atmospheric transport of precursor compounds or transport of PFOS through oceanic currents are likely important routes of exposure to background sites. Elevated concentrations of PFOS were detected in water, biosolids and air at WWTPs and in leachate and air of landfill sites. This highlights the contributions of WWTPs and landfills as sources of PFOS to aquatic systems and the atmosphere.
For the most part, levels of PFOS increased markedly from the early 1980s (or the start of data collection) until the late 1990s/early 2000s, corresponding to increased production volumes during this time. However, in recent years, concentration trends varied by media and location. More time may be required before the domestic and international measures related to PFOS are reflected consistently in all environmental media and locations. Continued input from PFOS-containing products still in use and continued use of PFOS products outside of North America may also be preventing decreases of concentrations in the environment.
Through comparison to the draft FEQGs, current PFOS concentrations that have been measured present a low potential for adverse effects on the organisms examined. However, PFOS in fish and bird eggs tended to exceed dietary guidelines for the protection of non-human mammalian and avian consumers, suggesting that this compound could represent a current risk to their wildlife predators. However, wildlife population health assessments are required to determine whether negative impacts are actually occurring. These results provide an important piece of information to be used by the Government of Canada in evaluating the risk management strategy for PFOS and considering how best to approach the risk management for similar substances of concern.
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