Exposure estimation during use and during weee treatment

• Author: Clemm, Christan; Löw, Clara; Baron, Yifaat; Moch, Katja; Möller, Martin; Köhler, Andreas R; Gensch, Carl-Otto; Deubzer, Otmar
• Pages: 38-46

RoHS Annex II Dossier, final

TBBP-A (flame retardant)

38

6. EXPOSURE ESTIMATION DURING USE AND DURING WEEE TREATMENT

6.1. Basis of exposure estimation

Before becoming WEEE, products containing covalently bound TBBP-A as part of epoxy or

polycarbonate resin based PWBs are not thought to release the substance to the environment.107

The stakeholder contribution of ZVEI (2018) underpins this claim by referring e.g. to the status report

of the ICL. JEITA and AEM stress the fact that no TBBP-A emissions from PWCs could be detected

although evidence was not provided.108 The presence of unreacted TBBP-A as a production residue

in finished epoxy-based printed wiring boards is negligible according to information provided by

stakeholders from industry. The FR4 laminates contain TBBP-A at levels of less than the detection

limits of either 10 or 20 ppm. Therefore, the unreacted residue levels can be considered as very low

(see also section 2.1).

The possibility of TBBP-A exposure resulting from additive use in polymers is higher than from

residues of unreacted TBBP-A residues in PWBs. In its form as an additive, TBBP-A is non-

covalently and therefore more loosely bound to the polymer than in its reacted form. Therefore, the

substance has a higher likelihood to be released from products in the use phase and when WEEE

is recycled or disposed of. However, as the volatility of TBBP-A is negligible air emissions will be

extremely small (US EPA 2015). TBBP-A may be released in the form of dust particles in the process

of shredding, crushing, and milling of flame retarded ABS plastics contained in WEEE.

6.2. Human exposure estimation

6.2.1. Exposure of workers of EEE waste processing plants

Modelled data

According to the waste streams examined in chapter 5.3 and 5.4 exposition of workers in WEEE

processing plants to TBBP-A can occur during the processes of dismantling and shredding. The

exposure can occur through inhalation of dust and dermal contact. The exposure route via inhalation

is assumed to be the more relevant one.

Exposure estimation for workers was modelled in the course of the preparation of the dossier at

hand by using the ECETOC’s Targeted Risk Assessment (TRA)109 tool. It helps calculating the risk

of exposure from chemicals to workers, consumers and the environment. The ECETOC TRA tool is

intended for manufacturing and formulation processes, therefore no appropriate processes to

describe the exposure conditions of waste treatment processes are available so far.

The process category 24: “high (mechanical) energy work-up of substances bound in materials

and/or articles” has been selected to calculate the exposure of workers of EEE waste processing

plants. This approach has been first introduced by the Austrian Umweltbundesamt for the RoHS

assessment of the phthalates DEHP, DBP and BBP; it has also been used by KEMI for the MCCP

107 Op. cit. Alaee, M., et al. 2003 and Buekens A. and Yang J. (2014)

108 Op. cit. ZVEI, JEITA and AEM (2018)

109 http://www.ecetoc.org/tools/targeted-risk-assessment-tra/