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BSEF Briefing Note – Tetrabromobisphenol A (TBBPA)

v 1.2, updated 18 April 2018 | Supersedes briefing note date 24th May 2017

Key Points

 

  • TBBPA is a sustainable and important flame retardant substance
  • Science shows that TBBPA is safe to use in all its applications
  • TBBPA in its intended uses and applications does not present a risk to human health or the environment

 

Introduction

These briefing points are intended to provide BSEF global representatives, affiliates (Flame Retardants Europe and NAFRA) and member companies with the necessary information and speaking points to enable them to respond to any enquires that may arise from downstream users of TBBPA in materials and products concerning its regulatory status.

 

About TBBPA

TBBPA is used as a reactive intermediate in the manufacture of certain brominated polymers and as an additive flame retardant in certain plastic applications. It is often cited as the brominated flame retardant with the largest production volume globally.

Its main use is in the production of printed circuit boards in electrical and electronic equipment to meet important fire safety requirements. More than 80% of TBBPA is used as a reactive flame retardant (resulting in a brominated epoxy polymer) which is used in electrical and electronic equipment, mainly in printed circuit boards. During this process, TBBPA is covalently bound or “reacted” into the polymer matrix and thus ceases to exist as the parent substance. In these applications, the potential releases of TBBPA are negligible[1].

Less than 20% is used as a raw material for brominated oligomers and polymers (covalently bound) and as an additive FR in plastics, mainly in acrylonitrile butadiene styrene (ABS) plastic, where it is encapsulated in the polymer matrix. ABS resins are used for enclosures of televisions and similar products. The potential for exposure to TBBPA when it is encapsulated in plastic is very low.

 

TBBPA in its intended uses and applications does not present a risk to human health or the environment

 TBBPA went through an 8-year EU Risk Assessment, which concluded that the reactive use of TBBPA presents no risk for human health and the environment. This was confirmed in June 2008 when the European Commission published a Decision with the conclusions of the Risk Assessment[2].

All of the data produced in the context of the EU Risk Assessment have been used to prepare the REACH registration dossier, which was submitted in 2010 to comply with the REACH registration deadline.

A study published by the European Food Safety Authority (EFSA) in December 2011 on the exposure of TBBPA and its derivatives in food, looking at 344 food samples, concluded that “current dietary exposure to TBBPA in the European Union does not raise a health concern”.

EFSA also determined that “additional exposure, particularly of young children, to TBBPA from house dust is unlikely to raise a health concern”.

A Canadian screening assessment report on TBBPA published in November 2013 concluded that TBBPA has negligible risk for human health. The report stated that current levels of TBBPA do:

  • Not have an immediate or long-term harmful effect on the environment
  • Not constitute a danger to the environment
  • Not constitute a danger to human life or health

In summary, regulatory agencies who have looked closely at TBBPA recognize that its uses as a reactive chemical intermediate do not represent a concern for human health and the environment.

 

Recent Developments

 Evaluation of TBBPA under REACH

 In March 2015 TBBPA (Tetrabromobisphenol A, CAS no. 79-94-7) was included in the EU’s Community Rolling Action Plan (CoRAP) for Evaluation under REACH, the EU‘s framework legislation on chemicals, mainly due to, “suspected toxicity to reproduction, potential to be an endocrine disruptor, suspected PBT/vPvB properties, and exposure of environment and consumers.”

As the Rapporteur, the Danish EPA’s assessment was completed in March 2016 and submitted to ECHA. A final decision on the Evaluation of TBBPA was agreed by the Member State Committee (MSC) of ECHA on 12th Dec. 2016 and published on the ECHA website[3] in May 2017.

Based on this assessment, the Danish authorities concluded that further studies are necessary. The studies are now being conducted by industry at independent test laboratories.  When completed, the results will then be submitted to ECHA and the Danish authorities for review.  Since a range of complex studies have been requested, a date for submission of the revised dossier (including all requested data) of 4th January 2021 was agreed. A final decision is expected in January 2022.

 

What does the Substance Evaluation mean for TBBPA?

Substance Evaluation in itself does not have any legal or regulatory impact on the production or use of the substance. It aims to clarify whether a substance, which has been identified as being of potential concern, poses an actual risk to human health and/or the environment and requests further information from the Registrants of the substance to verify the suspected concern, if necessary. As of this writing, TBBPA is one of currently 352 chemical substances having been named for substance evaluation under the CoRAP[4].

US NTP Carcinogenicity Review

In 2014 the US National Toxicological Programme (NTP) released its final technical report on the carcinogenicity of TBBPA. Two-year gavage studies provide evidence of carcinogenic activity in female rats (an increased incidence of uterine tumors), equivocal evidence in male rats (a slightly increased incidence of testicular adenomas), and some evidence in male mice (an increased incidence of liver tumors). There was no evidence of carcinogenic activity in female mice.

TBBPA has been reported as a non-mutagen because of negative results in bacterial reverse mutation assay (Ames assay) and chromosome aberration test in mammalian cells. This means that TBPPA does not develop tumors by directly interacting with the DNA (initiation), but promote tumors through non-genetic mechanisms (tumor promotion). The promotion effect is generally observed only at high-doses[5]. In summary, there is no concern for carcinogenicity of TBBPA at exposures to normal background concentrations (below the threshold value)[6].

 

Update of the REACH TBBPA Registration Dossier

On the basis of the NTP review findings and new information that became available regarding evidence relating to possible carcinogenicity effects of TBBPA, the Lead Registrant and the Brominated Compounds REACH Consortium (responsible for the registration dossier and chemical safety report (CSR)) decided, with advice from an external expert, to self-classify TBBPA as a category 2 carcinogen and to update the CSR and registration dossier accordingly. This is now publically disclosed on the ECHA web site.

The classification of TBBPA for this hazard endpoint has no impact on its use in materials and products for which it is intended nor for consumers. BSEF member companies are in the process of addressing the new classification with respect to the use and handling of TBBPA in production, transport and use by downstream use sectors.

 

International Agency for Research on Cancer (IARC) recent categorization of TBBPA

IARC issued a preliminary notice in February 2016 that TBBPA was assessed as a “probable carcinogen” (category 2A) in February 2016. This categorization of TBBPA is potentially confusing and misleading for users and product manufacturers since it only signifies that TBBPA has the potential to cause cancer but does not look at the risks from relevant human exposures. Of note also is the fact that in 2015, IARC chose to also place red meat in the same category.

As IARC itself notes: “IARC Monograph Programmes evaluate cancer hazards but not the risks associated with exposure. The distinction between hazard and risk is important. An agent is considered a cancer hazard if it is capable of causing cancer under some circumstances. Risk measures the probability that cancer will occur, taking into account the level of exposure to the agent. The Monographs Programme may identify cancer hazards even when risks are very low with known patterns of use or exposure”.

IARC is in the process of producing the full proceedings, or monograph, concerning its deliberations and rationale for concluding the categorization allocated to TBBPA along with some other industrial chemicals. This monograph has not been published yet.

China Priority Control Chemicals

China’s Ministry of Environmental Protection (MEP) has published the first batch of priority control chemicals on 28 December 2017 in conjunction with the Ministry of Industry and Information Technology (MIIT) and the National Health and Family Planning Committee (NHFPC)[7]. The list consists of 22 substances. TBBPA had initially been considered for inclusion in the list, but after having evaluated all the available scientific data, it was decided not to put TBBPA on the list.

 

TBBPA being assessed under EU (RoHS) Directive

The EU Commission has started a review of the substances restricted under RoHS[8], the « Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment”. Article 6 of RoHS requires in a periodic review of the list of restricted substances.

The scope of work includes a review and update of the existing methodology to identify and assess substances for possible restriction as well as a detailed assessment of seven new substances for possible future restrictions. These substances include Tetrabromobisphenol A (TBBPA).

The review is expected to be complete by June 2019. It explicitly allows for stakeholder participation. We do not anticipate any regulatory decision to emerge from this review before end 2020 or later.

BSEF’s view is that TBBPA’s use in E&E equipment is safe and there is no scientific basis to add it to the list of restricted substances. BSEF is fully participating in the review to ensure that the updated methodology is underpinned by science and the resulting assessment takes full account of the principle of risk enshrined in the RoHS Directive.

 

Summary

 

  • There are no restrictions on TBBPA globally
  • EU Risk Assessment confirmed that reactive use of TBBPA does not present a risk to human health or the environment
  • The NTP and IARC are hazard assessments that do not consider exposure
  • REACH Evaluation: industry has been requested to carry out some additional testing. A date for submission of the revised dossier (including all requested data) of 4 January 2021 has been agreed. The REACH registration remains valid and no impact on TBBPA is expected in the near future
  • EU started review of restricted substances under RoHS. TBBPA is one of the candidate substances. No regulatory decision expected before end 2019

 

BSEF Secretariat                                                                                                                               18th April 2018

 

[1] Yang, F and Nelson, G. (2016) Comprehensive Evaluation of Unreacted Flame Retardants in Printed Circuit Boards. Final report to ACC. Manuscript for publication in preparation

[2] http://echa.europa.eu/documents/10162/17313d17-5691-48cc-b7cc-126c06c6458a

[3] https://echa.europa.eu/documents/10162/84afb981-a86f-b3fe-dab8-df0c8d86fa08

[4] A full list of CoRAP substances can be accessed here

[5] Pecquet et al 2017 ; Derivation of a no‐significant‐risk‐level for tetrabromobisphenol A based on a threshold non‐mutagenic cancer mode of action, https://doi.org/10.1002/jat.3594

[6] The rats in the NTP study were exposed to TBBPA levels > 1 million times higher than Health Canada’s highest estimate of human exposures. Hence, there is no risk expected to humans from TBBPA if they are exposed to normal background concentrations.

[7] http://www.mep.gov.cn/gkml/hbb/bgg/201712/t20171229_428832.htm (in Chinese)

[8] http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011L0065