2 Background contamination in the analytical blanks. The MAC is based on exposure solely to Binary option strategy 2013 tx68. MACs for PFOS and PFOA should not exceed 1.
0 Executive summary PFOS is a man-made compound that does not occur naturally in the environment. It is no longer manufactured, imported, sold, offered for sale or used in Canada, but is still found in the environment because of its extremely persistent nature. This guideline technical document reviews and assesses all identified health risks associated with PFOS in drinking water. It incorporates available studies and approaches and takes into consideration the availability of appropriate analytical methods and treatment technology. Health Canada continues to monitor new research and will work with provinces and territories to update the guideline, or develop new guidelines or other technical support material, as needed to reflect significant changes in the weight of evidence.
Some cancer effects were observed in humans after exposure to PFOS, but no clear links could be made due to various study limitations. Tumours were observed in the liver, thyroid, and mammary gland of rats following long term exposure to PFOS. Both cancer and non-cancer endpoints were considered in the derivation of the MAC for PFOS in drinking water. The non-cancer approach, based on liver effects in rats, was used to calculate a MAC that is protective of human health from both cancer and non-cancer effects. Because PFOS remains in the human body longer than in does in rats, an approach that accounts for this difference was used in the derivation of the MAC for PFOS in drinking water. 2 Exposure Canadians can be exposed to PFOS through its presence in food, consumer products, dust, and drinking water.
Exposure is mainly from food and consumer products, however, the proportion of exposure from drinking water can increase in individuals living in areas with contaminated drinking water. Although PFOS is not regularly monitored at water treatment plants in Canada, the analysis has been performed for a few locations. 3 Analysis and treatment To date, the United States Environmental Protection Agency has not approved any analytical methods for the analysis of PFOS in drinking water. There are some methods that can be used to measure PFOS in drinking water at levels well below the MAC. However, they require good quality control procedures to get accurate results. Conventional treatment is not effective for PFOS removal. Other treatment methods are promising, although full-scale studies are limited.
4 Additivity The health effects of PFOS and PFOA are similar and well documented. Recent scientific evidence shows that PFOS and PFOA affect the same organ in similar ways. Thus, when PFOA and PFOS are found together in drinking water, the best approach to protect human health is to consider both chemicals together when comparing to the guideline values. EPA has established a non-regulatory lifetime health advisory of 0.