Targeted expert consultation: cycloxydim

5-19 November 2012

Questions and instructions for contributors

Targeted expert consultation on harmonised classification of cycloxydim (EC No 405-230-9, CAS No 101205-02-1) with regard to reproductive toxicity.

The Committee for Risk Assessment (RAC) is currently developing an opinion on a proposal for the harmonised classification of cycloxydim for flammability (according to criteria in Annex VI, Dir. 67/548/EEC). The proposal was submitted to ECHA in August 2011 and has been subject of a public consultation ending on 1 October 2011.

RAC is currently discussing the potential reproductive toxicity of cycloxydim. Therefore, this targeted expert consultation, aims to provide the parties concerned with an opportunity to comment on the questions presented below related to the reproductive toxicity of cycloxydim.

• 1. How can the maternal effects in the two-generation study (Hellwig et al., 1988) and developmental toxicity studies (Hellwig and Hildebrand 1987 (a)(b) and (c)) in the rat be interpreted in relation to the developmental toxicity of cycloxydim?
• 2. The pup effects in rats that may be critical for classification are outlined below (Hellwig and Hildebrand 1987(a)).
  • A. Dumb-bell shaped ossification centres in the thoracic region, were observed at a foetal incidence of 30% vs. 2.5% in the high dose (400 mg/kg bw/day) and control group, respectively.
    Dumb-bell shaped or bipartite ossification centres of vertebral body/bodies with involvement of cartilage are assessed as a variation in the CLH  report.
    However, the expert group on harmonisation of rat foetal skeletal terminology (Solecki et al., 2001, p. 718) concluded "The term dumb-bell implies that the bone precursor is affected as well as the ossification site and the change is likely to be permanent. Therefore, the condition would classify it as a malformation."
  • B. Incomplete ossification sternebrae was observed at a foetal incidence of 33% vs. 5.1% in the high dose (400 mg/kgbw/day) and control group, respectively.
    Incomplete ossification of the sternebrae (cartilage present) is assessed as a retardation in the CLH report.
    The expert group (Solecki et al. 2001) judged incomplete or unossified structures usually (except cranium effects) as a variation because of its transient nature.
    Incidences of both effects remained increased by post-natal day 21 (see post-natal segment findings in the study of Hellwig and Hildebrand, 1987b, page 118-119 in the CLH report)
• 2.1 Do you interpret these skeletal effects, i.e. dumb-bell shaped ossification centres in the thoracic region and incomplete ossification of the sternebrae, as anomalies/variations/retardations?
• 2.2 Do you assess these skeletal findings as relevant for classification and why?

Contributors

The experts should submit their input to the key questions in writing by 19 November 2012 at the latest.

The written input should reply to the key questions above and it should include a  summary text of a maximum of 250 words that outlines the response to the key questions.

This email should include:

• The identity of the parties concerned and a brief statement on why the party in question is considered as a party concerned
• The name and contact details of the expert

Depending on the number and/or volume of comments, either the full expert comment or only the summary will be published on the ECHA website in an Annex to the RAC opinion.

If an access to documents application pursuant to Regulation (EC) No 1049/2001 on public access to documents is received regarding this information (i.e. the written input); in order to define its position, ECHA will have to first perform an assessment of the content of this information. Therefore, when you submit the information mentioned above please indicate if any reason on why disclosure of this information should be denied exists. ECHA can examine as valid only reasons appearing in Article 4 of the Regulation (EC) No 1049/2001 on public access to documents.

Disclaimer

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