Human health hazard profile

• Author: Clemm, Christan; Löw, Clara; Baron, Yifaat; Moch, Katja; Möller, Martin; Köhler, Andreas R; Gensch, Carl-Otto; Deubzer, Otmar
• Pages: 21-24

RoHS Annex II Dossier, final

TBBP-A (flame retardant)

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3. HUMAN HEALTH HAZARD PROFILE

According to the harmonised classification in Annex VI of the CLP Regulation, TBBP-A is not

classified for human health hazards. However, 13 notifiers, among them a joint submission of a

REACH registration dossier, classify TBBP-A as carcinogenic Category 2 (H351 - Suspected of

causing cancer). In summary, the C&L brief for TBBP-A, provided by ECHA, states that “this

substance is suspected of causing cancer”.55

The most recent report of DEPA (2015),56 which was prepared for the purpose of justifying the

selection of TBBP-A for CoRAP inclusion, summarised that there is potential for endocrine disrupting

effects and toxic effects on reproduction and development (see explanation in the following section).

Concerns raised about TBBP-A, being suspected PBT, are summarised in the section on environ-

mental hazards (section 3.3).

3.1. Endpoints of concern

On the potential endocrine disrupting effect of TBBP-A, DEPA57 summarises the following:

“In vitro studies have demonstrated that TBBP-A has a high potency in competing with T4 for binding

to transthyretin (TTR) in animals, however no firm conclusions regarding the affinity of TBBP-A for

TTR in vivo can be drawn from the limited data available. The main target for TBBP-A human toxicity

is thyroid hormone homeostasis, and most of the studies indicated a decrease in serum T4. In

addition, weak estrogenic potency has been found, but TBBP-A did not induce CYP1, CYP2B1 or

CYP3A mRNA, protein and respective monooxygenase activities. The BMDL10 of 16 mg/kg bw for

changes in circulating thyroid hormone levels could, in principle, be used as the basis to derive a

human health-based guidance value.

Furthermore, Environment Canada/Health Canada reported that there is some recent evidence to

suggest that TBBP-A may be capable of disrupting normal functioning of the thyroid system in

amphibians and fish, and enhancing immune system activity in marine bivalves. This may further

support the findings already described.”

The acute toxicity of TBBP-A is reportedly rather low by all routes of exposure (oral, dermal,

inhalation) as well as for repeated dose toxicity. Information on effects is not available. Furthermore,

the EU RAR (2008) stated that there was no data on carcinogenicity nor information that indicated

toxicologically significant effects on fertility or reproductive performance at doses of up to 1,000

mg/kg.

The consultants note however that the EU RAR is older (2008) and based on data generated prior

to its publication. It thus needs to be assumed that the statements of Environment Canada/Health

Canada cited by DEPA (2015) regarding human toxicity and endocrine properties may be based on

more recent data. The current substance evaluation under REACH based on DEPA (2015) anyhow

aims to generate current data regarding endocrine disruption and PBT properties.

In its contribution to the 2nd stakeholder consultation, the Norwegian Environment Agency indicated

their notification to ECHA´s Registry of Intention (RoI) that it will develop a proposal for classification

55 Opt. cit. ECHA Brief Profile: Entry for TBBPA (2019)

56 Danish Environmental Protection Agency DEPA (2015): Justification for the selection of a substance for CoRAP

inclusion, 2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol

57 Opt. cit. DEPA (2015)