Brominated flame retardants, PFOS, Exposure, HBM
Brominated flame retardants (BFRs) and perfluoroalkyl substances (PFASs) have found extensive use in consumer applications such as electrical and electronic goods, soft furnishings, and building insulation foam to impart properties such as flame retardancy and stain resistance. Such use has led to environmental contamination and human exposure. Owing to concerns about their environmental persistence, ability to bioaccumulate and potential adverse health effects in humans and wildlife, some BFRs and PFASs have been listed under the Stockholm Convention on Persistent Organic Pollutants (POPs), an international treaty designed to eliminate POPs from the environment. Previous studies have revealed low levels of BFRs and PFASs in Irish foodstuffs and human milk. However, no such data existed for Ireland prior to this project about the presence of both BFRs and PFASs in indoor air and dust, and of PFASs in drinking water. This project therefore measured selected BFRs and PFASs in indoor air and dust from Irish homes, offices, cars, and school classrooms (n=30 per microenvironment category). The same contaminants were measured in 16 samples of human milk donated by Irish mothers, created from samples from 92 individuals. PFASs were also measured in samples of Irish tap (n=85) and bottled water (n=31). Comparison of concentrations of BFRs in human milk in this study and in a previous Irish study conducted in 2011, reveal restrictions on the manufacture and use of hexabromocyclododecane and both the Penta- and Octa-bromodiphenyl ether products appear to have been successful in reducing concentrations in Irish human milk. Likely as a consequence of the more recent ban on manufacture and use of the Deca-BDE product, concentrations in human milk in this study show no significant decline compared 2011. Moreover, while in 2011, decabromodiphenyl ethane (DBDPE) - a likely replacement for Deca-BDE - was not detected in any human milk sample, DBDPE was detected in 3 samples in this study. This implies increasing use of DBDPE as a “drop-in” replacement for Deca-BDE, and is supported by our findings that concentrations of DBDPE in both indoor air and dust in this study are the highest reported to date anywhere. While this is likely because this study is one of the few conducted since the listing of Deca-BDE under the Stockholm Convention and that future studies elsewhere will likely reveal similarly elevated concentrations of DBDPE; it suggests further research into exposure to DBDPE and its health effects is a priority. With respect to PFASs, perfluorooctanoic acid (PFOA) dominated air and drinking water, while perfluorobutane sulfonate (PFBS) dominated dust. PFOS concentrations in classroom air exceeded significantly those in homes. Concentrations of PFOA, perfluorononanoic acid (PFNA), and methyl perfluorooctane sulfonamido ethanol (MeFOSE) in air, were significantly higher in cars containing child car seats than in cars without. PFOS, PFOA, PFBS, and perfluorohexane sulfonate (PFHxS) were all detected frequently in drinking water but concentrations of PFASs were low, and although PFASs were 64 ng/L in one bottled water sample, this fell below a Swedish Action Level of 90 ng PFASs/L. The Irish population’s exposure to PFOS and PFOA via non-dietary sources is well below estimates of dietary exposure elsewhere in Europe. Moreover, even under a high-end exposure scenario, it falls below the European Food Safety Authority’s (EFSA) provisional tolerable weekly intakes (TWIs) for PFOS and PFOA. Concentrations of PFOA, PFOS, PFHxS, and PFNA in Irish human milk are within the range of those reported elsewhere in the world. Other PFASs were not detected in human milk. Reassuringly, concentrations of PFOS and PFOA in Irish human milk currently do not indicate a health concern, based on breastfeeding exposure scenarios carried out by EFSA. Application of a simple pharmacokinetic model suggests current adult exposure in Ireland to PFOS is below EFSA’s provisional TWI. In contrast, the model predicts that the maximum concentration detected in human milk in this study, implies a level of adult exposure that would exceed EFSA’s provisional TWI for PFOA. Given that the health effects of PFASs other than PFOS and PFOA are currently under review by EFSA and that this study found non-dietary exposure of children to PFBS exceeds that of the other PFASs targeted in this study, it is recommended that as well as continuing to measure PFOS and PFOA, future research should also monitor exposure to other PFASs such as PFBS, as well as PFHxS and PFNA that were detected in human milk.