Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

Abstract

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Keywords: PBDEs; Polybrominated diphenyl ethers; food; human exposure; occurrence; risk assessment; toxicology.

FIGURE 1

General structure of PBDEs.

FIGURE 2

Levels of PBDEs in indoor dust samples from different continents (from Coelho et al., 2014).

FIGURE 3

Levels of PBDEs in indoor dust samples from different environments (houses, cars, public places and offices (from Coelho et al., 2014).

FIGURE 4

Levels of PBDEs in indoor dust samples collected by different methods. SVC: specific vacuum cleaner or domestic cleaner with a nylon sock; HVB: Household vacuum cleaner (from Coelho et al., 2014).

FIGURE 5

Concentrations of the sum of 8 PBDEs (BDE‐28, ‐47, ‐99, ‐100, ‐153, ‐154, ‐183, ‐209) in different species from Florida coastal waters (lipid‐normalised concentrations) (from Zhang, Wang, et al., 2016). © 2016 Zhang et al Creative Commons Attribution License.

FIGURE 6

Suggested general mammalian metabolic pathway of BDE‐47 based on Marsh et al. (2006). Four postulated BDE‐47 epoxide intermediates lead to formation of six OH‐tetraBDE metabolites ((1) to (6)). Each OH‐tetraBDE may undergo debromination to form the three OH‐triBDE metabolites ((7) to (9)). Note: (1) 6‐OH‐2,2′,4,4’‐tetraBDE, (2) 5‐OH‐2,2′,4,4’‐tetraBDE, (3) 4‐OH‐2,2′,3,4’‐tetraBDE, (4) 2’‐OH‐2,3′,4,4’‐tetraBDE, (5) 3’‐OH‐2,2′,4,4’‐tetraBDE, (6) 4’‐OH‐2,2′,4,5’‐tetraBDE, (7) 2’‐OH‐2,4,4’‐triBDE, (8) 3’‐OH‐2,4,4’‐triBDE, (9) 4’‐OH‐2,2′,4‐triBDE.

FIGURE 7

Suggested metabolic pathway of BDE‐154 in male rats based on characterisation of metabolites in faecal extracts (reproduced from Hakk et al., 2009) © Taylor and Francis Online. (I) mono‐OH‐hexaBDE (five isomers), (II) mono‐OH‐pentaBDE (four isomers), (III) mono‐OH‐tetraBDE (two isomers), (IV) di‐OH‐hexaBDE (one isomer), (V) di‐OH‐pentaBDE (two isomers), (VI) tri‐OH‐pentaBDE (one isomer).

FIGURE 8

Suggested general mammalian metabolic pathway of BDE‐209. Debromination of BDE‐209 is a prerequisite for the formation of OH‐nonaBDE metabolites (from EFSA CONTAM Panel, 2011b).

FIGURE 9

Distribution of occurrence values reported for PBDEs across different European countries.

FIGURE 10

Distribution of occurrence values reported for PBDEs by year.

FIGURE 11

Percentage of analytical results below LOD, below LOQ and quantified values in the final dataset across the different food categories (FoodEx2 Level 1). The sum of percentages for non detected, non quantified and quantified values is not always 100% due to rounding.

FIGURE 12

Proportion of non detected, non quantified and quantified analytical results across the 10 congeners considered (BDE‐28, ‐47, ‐49, ‐99, ‐100, ‐138, ‐153, ‐154, ‐183 and ‐209). The sum of percentages for non detected, non quantified and quantified values is not always 100% due to rounding.