In an article published on February 14, 2019 by news provider Chemical Watch, correspondent Leigh Stringer informed about a recommendation by the U.S. scientific organization the Association Advancing Occupational and Environmental Health (ACGIH) to lower the inhalation threshold limit for antimony trioxide (CAS 1309-64-4). The organization’s current recommended limit of 0.5 mg/m3 was set in 1979, and the new proposed limit lowers it to 0.02 mg/m3. If regulatory bodies were to adopt this newly recommended limit, “many users of the substance would face problems across their production processes, as well as higher costs” according to industry group the International Antimony Association (i2a).

The new limit was developed based on the lowest concentration of respirable antimony that led to development of chronic lung effects in mice and rats (3 mg antimony/m3) in studies completed by the U.S. National Toxicology Program (NTP). However, i2a’s press release on the proposal argues that “very little detail is provided regarding the fashion in which respirable aerosol impacts in the NTP studies were converted to a proposed inhalable limit or the uncertainty factors that were applied.” The ACGIH’s proposal is open for comment until May 31, 2019.

Antimony trioxide is reasonably anticipated to be a human carcinogen (FPF reported), and it is frequently used as a catalyst in the production of polyethylene terephthalate (PET) (FPF reported). Antimony has been previously measured in food contact materials including food trays, straws, and single use drink bottles (FPF reported).

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Leigh Stringer (February 14, 2019). “Antimony trade group raises concerns over proposed threshold limit.Chemical Watch

i2a (February 7, 2019). “ACGIH publishes new TLV for ATO, with comments due by 31 May 2019.(pdf)

ACGIH (2019). “Antimony Trioxide: TLV(R) Chemical Substances Draft Documentation, Notice of Intended Change.