Tetrabromobisphenol A

Definition of tetrabromobisphenol–A: Tetrabromobisphenol–A (TBBP-A) is a brominated organic compound. It's primary used as an intermediate in the production of flame retardants like PBDEs, but can also be used as a flame retardant itself. This is the common definition for tetrabromobisphenol–A, other definitions can be discussed in the article

Notes

tetrabromobisphenol–A
Formula
C15H12Br4O2

Tetrabromobisphenol-A is produced in the USA, Israel and Japan but not in the EU. Current production is estimated between 120.000 and 150.000 ton each year, of which approximately 40.000 ton is each year exported to the European Union.

Tetrabromobisphenol-A is likely to reach the marine environment largely through industrial waste waters from land-based industrial activities. A smaller contribution to releases to water comes from particulate losses from products containing the substance over their lifetime. Emissions to air are smaller than those to water, and most such emissions are expected to be deposited close to the sources of emission. There are however some indications of possible transport over longer distances, possible adsorbed to particulate matter, which could lead to a contribution to the marine environment through this route.

No data are available on loads of tetrabromobisphenol-A entering the OSPAR Convention Waters and the Greater North Sea.

There are no available measured levels of tetrabromobisphenol-A in marine waters, but there are measurements in estuarine sediments, as well as in freshwaters, freshwater sediments and waste waters. A summary of these data2 is included in Tables 2 to 4. The available data on the levels of tetrabromobisphenol-A in aquatic biota are summarised in Table 5.

Tetrabromobisphenol-A is not considered to fully meet the PBT criteria as its liability to biaccumulate is below the threshold set by OSPAR. It is, however, persistent and toxic. The potential for tetrabromobisphenol-A to degrade under anaerobic conditions to form bisphenol-A is also still being investigated within the ESR process. Tetrabromobisphenol has been detected in freshwater, freshwater sediments and estuarine sediments but there are no available measured levels in marine waters. It has been detected in marine biota

The classification of tetrabromobisphenol-A against the EC Technical Guidance Document PBT criteria gave the following results: Persistence: tetrabromobisphenol-A is not considered to be readily biodegradable in the risk assessment, hence it meets the screening criteria for P or vP.

Bioaccumulation: the highest measured BCF value for fish is 1 234 l/kg, and there are several other determinations below this value. This value is below the cut-off value of 2 000, and so tetrabromobisphenol- A does not meet the B criterion.

Toxicity: the toxicity criterion used in the marine risk assessment guidance is a chronic NOEC <0,01 mg/l. There is some uncertainty over the actual NOEC for tetrabromobisphenol-A but the currently available data indicate that the NOEC for tetrabromobisphenol-A is around 0,0026 mg/l. Based in this result, it can provisionally be concluded that tetrabromobisphenol-A meets the toxicity criterion.

Conclusion of the PBT assessment Tetrabromobisphenol-A meets two of the three criteria for the PBT assessment. Although the measured BCF value is around 60% of the threshold value, it is considered to be a maximum value as it may include accumulation of metabolites. There are also indications for some degradation of tetrabromobisphenol-A under both aerobic and aerobic conditions. Overall, tetrabromobisphenol-A is not considered to meet the PBT criteria.

Tetrabromobisphenol-A is very toxic to aquatic organisms, it does not degrade readily in the environment and shows a high accumulation in fish (BCF>100). The detailed properties of tetrabromobisphenol-A, including numerical values for toxicity, persistence and bioaccumulation are set out in the fact sheet at Appendix 2. This fact sheet includes the more recent values which have come to light in the RAR. TBBPA has demonstrated no endocrine disrupting effects in any of the tests available.

The overall data set for tetrabromobisphenol-A consists of NOEC values for freshwater fish (NOEC 0,16 mg/l), two species of freshwater invertebrates (lowest NOEC 0,12 mg/l), two species of marine invertebrates (lowest NOEC/EC10 = 0,0026 mg/l for shell regrowth in Crassostrea virginica), and one freshwater algal species (NOEC ≥5,6 mg/l). In addition acute EC50 values (but no NOEC values) are available for one freshwater algal species and three marine water algae (lowest EC50 is 0,09 mg/l). The substance has been shown to have little or no estrogenic activity in the fish, invertebrates and amphibians tested so far. There is some evidence that the toxicity of tetrabromobisphenol-A to marine algae may increase with decreasing pH in the range pH 7,6 to 8,2, but, given that natural seawater is effectively buffered at around pH 8 such trends in toxicity are not likely to be important in reality.

From the Technical Guidance Document an assessment factor of 50 could be applied to the available data as there are NOECs from freshwater/marine species covering three trophic levels (algae, fish and crustaceans) with in addition a long-term NOEC from an additional marine taxonomic group (molluscs). As marine as well as fresh water species have been tested in two of the trophic levels (algae and crustaceans) it could be considered to reduce the assessment factor to a value of 10. However, there is some uncertainty over the actual NOECs for some of the species tested (see main risk assessment report) and no NOEC has been determined for marine algae. The uncertainty over the NOECs means that it is not currently possible to derive a reliable PNEC for the aquatic compartment. Therefore an assessment factor of 50 will be used on the extrapolated EC10 of 0,0026 mg/l for Crassostrea

virginica to derive an indicative value of 0,052 μg/l for the marine risk assessment.