The Perfluorochemicals (Pfcs) in Homes and Gardens Study (PIHGS): Implications for Human Exposure Assessment.

Abstract

Background: Since 2004, Minnesota has been responding to the presence of PFC contamination in several Twin Cities area drinking water supplies. Wells with levels of PFCs exceeding state health department guidelines have been mitigated through installation of granular activated carbon filtration systems. Residents now drink water with no to low levels of PFCs. In PIHGS, MDH sought to determine if past or present PFC water and soil contamination impact PFC levels in home-grown produce. Methods: In 2010, exterior tap water, garden soil, and produce samples were collected at homes with a history of water contamination. Water, soil, and produce samples were analyzed for seven PFCs. Results: In water, perfluorobutanoic acid (PFBA) was found most often and at higher concentrations compared to other PFCs. In soil, PFBA, perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA) were found in all samples and at the highest concentrations. PFBA water level and the amount of garden watering were significantly associated with soil concentration. In produce, PFBA was detected most often and at higher concentrations compared to other PFCs. Very few detects of PFOS and PFOA were found in produce. Significant contributors to PFBA in produce were PFBA water level, amount of watering, and produce type. Conclusions: PFBA in water influences levels in soil and produce. The results are consistent with experimental studies demonstrating greater uptake of short-chain PFCs (such as PFBA) over longer chain PFCs by edible plants. Although the general population is mainly exposed through the diet, mechanisms of PFC food contamination are poorly understood. Data are particularly lacking for shorter-chain PFCs even though they have the highest potential to contaminate water and bioaccumulate in crops. Based on PIHGS and related studies, the impacts of substituting shorter-chain compounds for long-chain PFCs in industrial processes should be carefully examined.