Following a request from the European Commission, the Panel on Contaminants in the Food Chain (CONTAM Panel) was asked to deliver a scientific opinion on brominated phenols and their derivatives in food. The present opinion will focus on brominated phenolic compounds and their derivatives, other than tetrabromobisphenol A (TBBPA) or TBBPA derivatives, since the latter have been dealt with separately in a previous opinion by the CONTAM Panel.
Brominated phenols and their derivatives comprise a complex group of brominated flame retardants (BFRs). Brominated phenols that have been identified as flame retardants include 2,4-dibromophenol (2,4-DBP), 2,4,6-tribromophenol (2,4,6-TBP), pentabromophenol (PBP), and tetrabrominated bisphenol S (TBBPS). 2,4,6-TBP, PBP and TBBPS are precursors of four non-phenolic derivatives also being applied as BFRs, i.e. TBP allyl ether (TBP-AE), PBP allyl ether (PBP-AE), TBP 2,3‑dibromopropyl ether (TBP-DBPE) and TBBPS bis(2,3-dibromopropyl ether) (TBBPS-BDBPE). These brominated phenols and their derivatives are used as reactive as well as additive flame retardants in a large range of resins and polyester polymers. Several of the commercially produced brominated phenols also occur as natural products in the marine environment.
A call for data on BFRs including brominated phenols was issued by the European Food Safety Authority (EFSA) in December 2009. No data on brominated phenols or their derivatives considered in this opinion were submitted to EFSA. A limited number of occurrence data was identified in the literature. Data from European sampling showed that 2,4,6-TBP predominates over the other brominated phenols. Levels of 2,4,6-TBP in fish meat of perch and Arctic char from < 0.03 to 3.5 ng/g wet weight (w.w.) were reported. Higher levels were reported for blue mussels (3.2 to 13 ng/g w.w.) and cod liver (86 ng/g w.w.). These data cover one food group only, “Fish and other seafood”, and therefore a meaningful exposure assessment for the general population is not possible. In order to provide some indication of whether there could be a possible health concern with respect to dietary exposure to 2,4,6-TBP, the CONTAM Panel made a tentative exposure estimate for the specific group of adult high consumers of fish, molluscs and crustaceans. The worst case exposure estimate for this population group was 40 ng/kg body weight (b.w.) per day.
Data on levels of brominated phenols in human milk are too limited to perform a meaningful risk assessment for breast-fed infants. In order to obtain a rough idea about the magnitude of exposure via human milk, the data on 2,4,6-TBP in one pooled sample of Norwegian human milk were used for a tentative exposure estimate. For 3 months old breast-fed infants with an average human milk consumption (800 mL per day) the concentration of 2,4,6-TBP human milk would result in a daily exposure of 3 ng/kg b.w. For infants with high human milk consumption (1 200 mL per day) the daily exposure would be 4 ng/kg b.w.
The limited toxicokinetics data suggest that, following oral administration to rats, 2,4,6-TBP is rapidly absorbed, distributed in different tissues such as kidney, lung and liver and eliminated, mainly via urine, within 48 hours. No information was found on metabolic pathways of 2,4,6-TBP. No data on the other brominated phenols considered in this opinion were identified.
Data on the toxicity of brominated phenols are generally lacking and most of the sparse information available relates to 2,4,6-TBP. In a few short-term oral toxicity studies in rats, liver and kidneys were the main targets. In a repeated dose oral toxicity study, which was combined with a reproduction/developmental toxicity screening test, a no-observed-adverse-effect level (NOAEL) for 2,4,6-TBP of 100 mg/kg b.w. per day was identified. In the reproduction/developmental phase of this study, reduced neonatal viability and reduced neonatal body weights were observed at a dose of 1 000 mg/kg b.w. per day. The NOAEL for developmental toxicity was 300 mg/kg b.w.
2,4,6-TBP did not induce gene mutations in bacterial cells, but induced chromosomal aberrations in mammalian cells. In vivo, no increase in micronuclei formation in bone marrow of mice was found. No long-term toxicity or carcinogenicity studies with 2,4,6-TBP were identified.
The CONTAM Panel concluded that due to the limitations and uncertainties in the current database, the establishment of a health based guidance value for 2,4,6-TBP was not appropriate. Therefore, the Panel derived a margin of exposure to assess the level of possible health concern.
Comparison of the NOAEL for 2,4,6-TBP of 100 mg/kg b.w. with the worst case dietary exposure estimate of 40 ng/kg b.w. per day for high consumers of fish, molluscs and crustaceans, results in an estimated margin of exposure of about six orders of magnitude. This margin of exposure is, however, so large that the CONTAM Panel concluded that it is unlikely that current dietary exposure to 2,4,6‑TBP in Europe would raise a health concern.
For breast-fed infants with average or high human milk consumption a margin of exposure of about seven orders of magnitude was estimated. Although the exposure estimate was only based on one pooled sample of Norwegian human milk, this margin is so large, that the CONTAM Panel concluded that it is unlikely that exposure to 2,4,6-TBP via breast feeding in Europe would raise a health concern.
Due to lack of data a risk assessment of the other brominated phenols or their derivatives is not possible.
The CONTAM Panel recommended that information on production rates and use of brominated phenols should be obtained, and that data on occurrence in food, especially of marine origin, should be generated.