Human health

On March 9, 2006 the second draft human health (HH) report of the ATO Risk Assessment (RA) was discussed at the EU’s Technical Committee for New and Existing Substances (TC NES) meeting in Arona, Italy. This second draft of the Risk Assessment report only contains the exposure scenarios (occupational exposure, consumer exposure and exposure via the environment), toxicokinetics and the mutagenicity effects. All other acute and chronic effects data had been deleted from the report again by KemI, including the risk characterisation.

ATOS has filled data gaps regarding acute toxicity (sensitisation, irritation, and inhalation toxicity), occupational exposure (particle size distribution- dermal exposure and absorption and dustiness) and finally mutagenicity studies (toxicokinetics and an in vivo clastogenicity study). These data provide conclusive evidence that ATO is neither a sensitizer, nor an eye or respiratory tract irritant.  Human data confirm that ATO is irritating to human skin and should thus be labelled with the R phrase, R38. Antimony trioxide is currently classified as dangerous substance within the meaning of Directive 67/548/EC as Carcinogen category 3 (implying Xn, harmful and R40 limited evidence of a carcinogenic effect).

ATO is not considered poisinous via oral ingestion. It has a high LD50 value > 20 g/kg body weight. Sub-chronic administration also does not result in systemic toxicity even at high doses. The oral absorption factor is < 1%; dermal absorption factor: < 1% and inhalation absorption factor: ~15%

Considering the results of a new toxicokinetics study and based on one new and one existing in vivo mutagenicity study, our scientists are convinced that ATO is not a mutagen (i.e. not a class 3 mutagen) and as a consequence should not be reclassified as a class 2 carcinogen and should remain in carcinogenicity class 3 (i.e. there is no data to justify classification as a possible carcinogen). The fact that ATO is not a mutagen has been confirmed by independent scientists in a recent publication in the international journal ‘Mutation Research’ in December 2006. The article’s title: “Failure of antimony trioxide to induce micronuclei or chromosomal aberrations in rat bone-marrow after sub-chronic oral dosing” is self-explanatory.

Based on the comments from industry and several member states, an enormous set of new study results and an extensive package of new exposure data from both producers and downstream users, the exposure scenarios, the effects section and the risk characterization are being revised by the rapporteur and a new report is expected the coming weeks for discussion at TC NES III in September 2007.

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