Rationale for inclusion of the substance in annex II of rohs

• Author: Clemm, Christan; Löw, Clara; Baron, Yifaat; Moch, Katja; Möller, Martin; Köhler, Andreas R; Gensch, Carl-Otto; Deubzer, Otmar
• Pages: 69-71

RoHS Annex II Dossier, final

TBBP-A (flame retardant)

69

10. RATIONALE FOR INCLUSION OF THE SUBSTANCE IN ANNEX II OF ROHS

TBBP-A is used in relevant quantities in EEE. Despite some data gaps it can be stated that the

largest part of the TBBP-A (about 90 %) is used as a reactive component in epoxy resins. Epoxy

resins for their part are the essential component of PWB type FR4 and can be found in practically

every type of EEE. In addition, epoxy resins can also be used as a sealing compound for electronic

components. The remaining 10 % of the TBBP-A applied in EEE is used as an additive flame

retardant, especially for plastic housings. On the basis of the data available and presented in this

dossier, it is open whether the quantities used for these applications have actually decreased or

whether this only applies to European manufacture, and whether the quantities of TBBP-A in

imported EEE components and equipment have remained stable or even increased in view of the

continuing consumption of EEE.

TBBP-A as a precursor for epoxy resins is the main application, however, releases of TBBP-A during

waste phase can mainly be attributed to its second application, the additive use as a flame retardant

in housings and encapsulations. This can be attributed to the fact that TBBP-A undergoes a chemical

transformation when used as a reactive component and – apart from low residual monomer contents

– is no longer present as such substance.

With regard to emissions of TBBP-A from WEEE treatment processes, it should be noted that the

relevant exposure of TBBP-A by dust in shredding processes of plastic housings and enclosures is

assumed to be the most relevant exposure scenario. Monitoring data from recent years was not

made available, so it is not possible to determine whether effects occur in EU facilities at a sufficient

magnitude at this stage or if the opposite is the case.

With regard to risks for human health, there are some reasons in favour of a restriction of TBBP-A

under RoHS:

• The current DNELs for TBBP-A do not take into account potential endocrine disrupting properties.

Instead, given the structural similarity of TBBP-A and BPA, it is proposed to take the DNELs of

bisphenol-A into account as a precautionary approach in order to reflect the potential endocrine

disrupting properties of TBBP-A. It is worth noting that this preliminary recommendation requires

further in-depth evaluation to validate the proposed results.

• The observation that workers of EEE waste processing plants are exposed to TBBP-A is confirmed

by exposure estimations, by measurements of TBBP-A in EEE waste streams and results from

human biomonitoring suggesting that TBBP-A has been detected in the serum of workers. Based

on these considerations, an impact on workers in EEE waste processing plants has been observed

and the estimated exposure by ECETOC TRA rather indicates a risk for workers via dermal

exposure than via inhalation.

• The general population is exposed to a TBBP-A pre-load through ingestion and inhalation of house

dust. Taking into account pre-load exposure to TBBP-A via house dust and taking the DNEL for

bisphenol A for oral exposure at 4 µg/kg bw/day as a precautionary approach, a risk

characterisation ratio of > 1 for children indicates a risk.

• As for the environment, according to monitoring data, TBBP-A is frequently detected and can thus

be seen as a ubiquitous contaminant. This indicates that it is continuously released into the

environment. For persistent substances, the normal risk assessment, by means of the ratio of the

expected environmental concentration (Predicted Environmental Concentration, PEC) and an

estimated non-effect threshold (Predicted No-effect concentration, PNEC) is not applicable.

Substances with PBT properties have the potential to persist and thereby accumulate in the