Approaches to mixture risk assessment of PFASs in the European population based on human hazard and biomonitoring data.

Per- and polyfluoroalkyl substances (PFASs) are a highly persistent, mobile, and bioaccumulative class of chemicals, of which emissions into the environment result in long-lasting contamination with high probability for causing adverse effects to human health and the environment. Within the European Biomonitoring Initiative HBM4EU, samples and data were collected in a harmonized way from human biomonitoring (HBM) studies in Europe to derive current exposure data across a geographic spread. We performed mixture risk assessments based on recent internal exposure data of PFASs in European teenagers generated in the HBM4EU Aligned Studies (dataset with N = 1957, sampling years 2014-2021). Mixture risk assessments were performed based on three hazard-based approaches: the Hazard Index (HI) approach, the sum value approach as used by the European Food Safety Authority (EFSA) and the Relative Potency Factor (RPF) approach. The HI approach resulted in the highest risk estimates, followed by the RPF approach and the sum value approach. The assessments indicate that PFAS exposure may result in a health risk in a considerable fraction of individuals in the HBM4EU teenager study sample, thereby confirming the conclusion drawn in the recent EFSA scientific opinion. This study underlines that HBM data are of added value in assessing the health risks of aggregate and cumulative exposure to PFASs, as such data are able to reflect exposure from different sources and via different routes.

PFAS levels and determinants of variability in exposure in European teenagers - Results from the HBM4EU aligned studies (2014-2021).

BACKGROUND: Perfluoroalkyl substances (PFAS) are man-made fluorinated chemicals, widely used in various types of consumer products, resulting in their omnipresence in human populations. The aim of this study was to describe current PFAS levels in European teenagers and to investigate the determinants of serum/plasma concentrations in this specific age group. METHODS: PFAS concentrations were determined in serum or plasma samples from 1957 teenagers (12-18 years) from 9 European countries as part of the HBM4EU aligned studies (2014-2021). Questionnaire data were post-harmonized by each study and quality checked centrally. Only PFAS with an overall quantification frequency of at least 60% (PFOS, PFOA, PFHxS and PFNA) were included in the analyses. Sociodemographic and lifestyle factors were analysed together with food consumption frequencies to identify determinants of PFAS exposure. The variables study, sex and the highest educational level of household were included as fixed factors in the multivariable linear regression models for all PFAS and each dietary variable was added to the fixed model one by one and for each PFAS separately. RESULTS: The European exposure values for PFAS were reported as geometric means with 95% confidence intervals (CI): PFOS [2.13 µg/L (1.63-2.78)], PFOA ([0.97 µg/L (0.75-1.26)]), PFNA [0.30 µg/L (0.19-0.45)] and PFHxS [0.41 µg/L (0.33-0.52)]. The estimated geometric mean exposure levels were significantly higher in the North and West versus the South and East of Europe. Boys had significantly higher concentrations of the four PFAS compared to girls and significantly higher PFASs concentrations were found in teenagers from households with a higher education level. Consumption of seafood and fish at least 2 times per week was significantly associated with 21% (95% CI: 12-31%) increase in PFOS concentrations and 20% (95% CI: 10-31%) increase in PFNA concentrations as compared to less frequent consumption of seafood and fish. The same trend was observed for PFOA and PFHxS but not statistically significant. Consumption of eggs at least 2 times per week was associated with 11% (95% CI: 2-22%) and 14% (95% CI: 2-27%) increase in PFOS and PFNA concentrations, respectively, as compared to less frequent consumption of eggs. Significantly higher PFOS concentrations were observed for participants consuming offal (14% (95% CI: 3-26%)), the same trend was observed for the other PFAS but not statistically significant. Local food consumption at least 2 times per week was associated with 40% (95% CI: 19-64%) increase in PFOS levels as compared to those consuming local food less frequently. CONCLUSION: This work provides information about current levels of PFAS in European teenagers and potential dietary sources of exposure to PFAS in European teenagers. These results can be of use for targeted monitoring of PFAS in food.

Comparisons of polybrominated diphenyl ether and hexabromocyclododecane concentrations in dust collected with two sampling methods and matched breast milk samples.

UNLABELLED: Household dust from 19 Swedish homes was collected using two different sampling methods: from the occupant's own home vacuum cleaner after insertion of a new bag and using a researcher-collected method where settled house dust was collected from surfaces above floor level. The samples were analyzed for 16 polybrominated diphenyl ether (PBDE) congeners and total hexabromocyclododecane (HBCD). Significant correlations (r = 0.60-0.65, Spearman r = 0.47-0.54, P < 0.05) were found between matched dust samples collected with the two sampling methods for ∑OctaBDE and ∑DecaBDE but not for ∑PentaBDE or HBCD. Statistically significantly higher concentrations of all PBDE congeners were found in the researcher-collected dust than in the home vacuum cleaner bag dust (VCBD). For HBCD, however, the concentrations were significantly higher in the home VCBD samples. Analysis of the bags themselves indicated no or very low levels of PBDEs and HBCD. This indicates that there may be specific HBCD sources to the floor and/or that it may be present in the vacuum cleaners themselves. The BDE-47 concentrations in matched pairs of VCBD and breast milk samples were significantly correlated (r = 0.514, P = 0.029), indicating that one possible exposure route for this congener may be via dust ingestion. PRACTICAL IMPLICATIONS: The statistically significant correlations found for several individual polybrominated diphenyl ether (PBDE) congeners, ∑OctaBDE and ∑DecaBDE between the two dust sampling methods in this study indicate that the same indoor sources contaminate both types of dust or that common processes govern the distribution of these compounds in the indoor environment. Therefore, either method is adequate for screening ∑OctaBDE and ∑DecaBDE in dust. The high variability seen between dust samples confirms results seen in other studies. For hexabromocyclododecane (HBCD), divergent results in the two dust types indicate differences in contamination sources to the floor than to above-floor surfaces. Thus, it is still unclear which dust sampling method is most relevant for HBCD as well as for ∑PentaBDE in dust and, further, which is most relevant for determining human exposure to PBDEs and HBCD.

POP levels in breast milk and maternal serum and thyroid hormone levels in mother-child pairs from Uppsala, Sweden.

In experimental studies, it has frequently been observed that the homeostasis of thyroid hormones (THs) is affected by exposure to persistent organic pollutants (POPs), such as dioxins and PCBs. In man, similar effects have been indicated in several epidemiological studies. In order to investigate the possible effect on THs at low background exposures found among the Swedish population the following study was performed. Primiparous women (n=395) in the Uppsala region were recruited between 1996 and 1999. Of these, 325 mothers agreed to donate a serum sample in late pregnancy and breast milk was obtained from 211 women 3 weeks after delivery. Babies were sampled for blood at 3 weeks (n=150) and 3 months (n=115) after birth. In connection to the sampling, questions on personal characteristics were asked. Levels of low (tri- to penta-) chlorinated PCB, di-ortho PCB, p,p'-DDE, (mono-ortho) PCB TEQ and PCDD/DF TEQ were monitored in breast milk and in mother's blood (not PCDD/DF). The results showed that the measured TH levels (thyroid-stimulating hormone - TSH, total tri-iodothyronine - TT3, free thyroxine - FT4) in mothers and children were within the reference range. Some significant associations were seen between POP exposures and TH levels in mother or child after simple regression analysis. Following adjustment for important confounding factors, the significant associations mostly disappeared. However, significantly decreasing TT3 levels with increasing prenatal low-chlorinated PCB exposure were still seen in 3 week old children, and on TT3 in mothers exposed to PCDD/DF. In conclusion, the study clearly shows the importance of adjustment for important confounding factors in the analysis of possible associations between POP exposure and hormonal effects. The remaining associations are weak in both children and mothers and the clinical consequences of these alterations are uncertain. When comparing studies that investigate associations between TH levels and POP levels during the perinatal stage, no obvious between-study concordance was seen regarding the critical dose for hormonal effects to occur.