Antimony Trioxide Profile

INDUSTRIAL CHEMICALS – POSSIBLE CARCINOGEN (IARC 2B)

How did CAREX choose this agent for review?

Antimony Trioxide Profile

General Information

Antimony trioxide (Sb₂O₃) is a slightly soluble, white crystalline powder.[1] It is produced by smelting antimony-containing ores[1] or reacting antimony trichloride with water.[2] Antimony is not abundant in the earth’s crust.[3] Antimony trioxide may also be referred to as diantimony trioxide (DAT), antimony oxide, or in manufacturing as antimony white.[4] There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.[4]

Antimony trioxide was last classified by the International Agency for Research on Cancer (IARC) in 1989 as Group 2B, possibly carcinogenic to humans, based on inadequate evidence in humans and sufficient evidence in animals.[1] Antimony trioxide is a respiratory carcinogen in female rats.[1]

The epidemiological literature on exposure to antimony trioxide is not extensive and is limited by difficulty in controlling for confounding variables. Recent reviews of studies report excesses of lung cancer in antimony exposed smelter workers, but factors such as smoking, exposures to PAHs and other metals (e.g. arsenic), were not appropriately controlled.[2,5]

Antimony trioxide has also been linked to pneumoconiosis, bronchitis, and airway inflammation.[3] Digestive and neurologic symptoms have been reported from high levels of exposure, but causal relationships have not been established.[3] An early study reported that exposure is associated with an increase in spontaneous abortions, premature birth, and slow growth rates in offspring.[6] The study’s control of confounding variables and exposure assessment techniques, however, were unclear.[7]

Regulations and Guidelines

Occupational Exposure Limits (OEL) [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]

Canadian Environmental Guidelines

Antimony trioxide was not included in other Canadian government environmental guidelines reviewed.[27,28,29,30]

Canadian Agencies/Organizations

Antimony trioxide was not included in other Canadian government chemical listings reviewed.[36]

Canadian Production and Trade

Canadian market demands for antimony trioxide are met through imports.[39] Most of the market for antimony trioxide is in flame retardants for use in vinyl fabrics, wire & cable, and other plastics and rubber.[39]

Approximately 125,000 tonnes of antimony metal are mined globally on an annual basis.[40] China is the dominant producer, taking on approximately 85% of production. South Africa, Russia and Bolivia produce lesser amounts.[40] Canada produces a very small fraction (0.1%) of global antimony metal.[41] The two primary lead smelters in Canada, located in Trail, BC and Bathurst, NB recover antimony metal as by-product from the ores. They also recycle antimonial-lead from lead-acid batteries.[41]

Four secondary lead smelters located in Quebec, Ontario, and BC use recycled batteries and isolate antimony metal from lead alloys during the process.[41] The Beaverbrook antimony mine in Newfoundland was closed in 1998 and reopened in 2008 when market conditions were more favourable. Its operations were again suspended in 2013 due to high operating costs.[40]

Production and Trade

t = tonne

Environmental Exposures Overview

The main source of exposure to antimony trioxide for the general population is through dermal contact with household items that contain flame retardants, such as paint, mattress covers and furniture upholstery.[44] However, Environment Canada reports that exposures from this pathway are low.[44]

Other sources of environmental exposure include food, drinking water, and air.[3,44] Overall, levels of antimony trioxide in water are low due to its poor solubility in water.[44] Higher levels of exposure may occur around smelters, incinerators, and near combustion of petroleum and coal products.[3] Higher levels of exposure to antimony trioxide have also been associated with smokers and those exposed to secondhand smoke.[45]

Searches of Environment Canada’s National Pollutant Release Inventory (NPRI) and the US Household Products Database yielded the following results on current potential for exposure to antimony trioxide in Canada:

NPRI and US Household Products Database

Occupational Exposures Overview

Inhalation is the most important route of occupational exposure, however oral and dermal contact are also a concern.[3]

CAREX Canada estimates that approximately 9,700 Canadians are exposed to antimony trioxide in the workplace. The primary industrial groups exposed are public administration, followed by glass and glass product manufacturing. In terms of occupations, the largest exposed groups are police officers (exposed in firing ranges) and welders. Other occupations that may be significantly exposed to antimony trioxide are textile processing and glass forming workers.

Other workers likely to be exposed include those involved in: antimony trioxide production; antimony processing, smelting, and packaging of antimony compounds; production of ceramics and alloys that contain Sb₂O₃; and manufacture and application of flame retardants.[38]

Workers in facilities that recycle lead-acid batteries may also be exposed to antimony.[48] Firefighters and other emergency workers may be exposed when materials containing antimony trioxide as a fire retardant combust.[38] Exposures may also occur for workers involved producing PET bottles, where antimony trioxide is used as the main catalyst.

For more information, see the occupational exposure estimate for antimony trioxide.

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