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: 68-69

RoHS Annex II Dossier, final

Diantimony trioxide (flame retardant)

68

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

Diantimony trioxide is used as a synergist for halogenated flame retardants (FR), which means that

the quantities of halogenated flame retardants applied in EEE can be reduced. The most relevant

applications for ATO are plastics (e.g. for EEE enclosures), cable insulations and resin-based Printed

Wiring Boards. Though stakeholders submitted additional information on some applications and

overall quantities, there is still a lack of specific information on the current quantities of ATO placed

on the European market as a constituent of EEE. It is recognised that this uncertainty is a

consequence of the high variety of possible formulations following specific technical requirements.

Next to its primary function as a FR synergist, ATO is used as a gravimetric parameter in post-

shredder sink-float sorting techniques during WEEE recycling. Owing to its high density, it aids the

separation of plastic that contains halogenated flame retardants. It is therefore concluded that ATO

facilitates WEEE management as it improves the detection and separate disposal of plastics

containing halogenated FR.

With regard to risks for human health, it is concluded that workers in WEEE recycling plants are

exposed to ATO especially in dismantling and shredding processes. However, the estimated

potential exposure is put into perspective by measurements at operational e-recycling facilities.

Although the sample size is limited in numbers, these workplace measurements are below the

national occupational exposure limits. However, as ATO is suspected of being carcinogenic, there

is reason to invoke the precautionary principle to intensify the monitoring of occupational exposure

to ATO in recycling plants.

Although alternatives to ATO in its function as a FR-synergist are available, a mono-substitution

(substituting only ATO as synergist) does not currently seem to be applied in EEE products on the

market.

The application of alternatives to the combination ATO and halogenated flame retardants (co-

substitution) is confirmed by waste stream analysis, which means that phosphorus-based flame-

retardant plastics is found in the waste stream. Ecolabel schemes as well as voluntary industry

policies demonstrate that a replacement of the system halogenated FR / synergist is feasible in some

of the application areas, if not in all of them. A restriction of ATO alone could lead to so-called

regrettable substitution, in other words, cause increased use of halogenated flame retardants. The

increased use of halogenated FR is expected to be more harmful to human health and the

environment than the net benefit of an ATO restriction. Furthermore, there are possible substitutes

that are suspected to entail adverse human health impacts, e.g. some arylated organophosphates.

Such regrettable substitution is to be avoided in co-substitution.

In summary, despite its suspected carcinogenic properties, is not recommended to add

diantimony trioxide to Annex II of the RoHS Directive. The main reason is that occupational

exposure limits can be met during WEEE recycling. A secondary reason is the function of ATO as a

FR synergist that allows for a reduced use of halogenated FR in EEE.

Additional recommendation for a group assessment of FR-synergist systems

From the background of the aforementioned trade-offs in environmental and health effects, the

consultant suggests undertaking a joint assessment of the system of halogenated flame retardants

and the ATO synergist.