Antimony
(endorsed 1996)
Guideline
Based on health considerations, the concentration of antimony in drinking water should not exceed the limit of determination of 0.003 mg/L.
General description
Antimony, as the trivalent (Sb(III)) or pentavalent (Sb(V)) salts, has occasionally been detected in natural source waters. Occurrences are more common in areas near lead or copper smelting operations. Antimony–tin solder is beginning to replace lead solder and hence exposure to antimony in drinking water may increase in the future.
Antimony alloys and compounds are used in semiconductors, batteries, anti-friction compounds, ammunition, cable sheathing, and flame-proofing compounds. Antimony salts are used in glass, and in the manufacture of ceramics and pottery.
Studies overseas have generally found low concentrations in drinking water, typically less than 0.005 mg/L, but higher concentrations have been reported occasionally. There are few data available on antimony concentrations in food. The United States Agency for Toxic Substances and Disease Registry has suggested that average daily consumption of antimony in food is about 0.018 mg.
Typical values in Australian drinking water
Australian drinking water supplies have not been routinely monitored for antimony.
Treatment of drinking water
There are no published methods for removal of antimony from drinking water.
Measurement
The concentration of antimony in drinking water can be determined by hydride generation followed by analysis using atomic absorption spectroscopy. The limit of determination is approximately 0.001 mg/L. Alternatively, graphite furnace atomic absorption spectroscopy can be used with a limit of determination of 0.003 mg/L (APHA Method 3500-Sb Part B 1992).
Health considerations
Studies using rats have shown that about 15% of antimony is absorbed by the gastrointestinal tract. It is distributed mainly to the liver, spleen and heart, and to the thyroid and adrenal glands, and it is excreted in faeces and urine.
There have been a number of studies on the effects of long-term human exposure to antimony. One early study of adult male workers in an antimony smelter reported no adverse effects after persistent exposure over periods from 2 to 13 years. A more recent study where workers were exposed for 9 to 31 years to dust containing antimony trioxide and antimony pentoxide reported respiratory and eye problems as well as staining of the front tooth surface. A dermatitis condition was observed in more than half of the exposed workers. Other studies have reported heart irregularities, lung cancer, and spontaneous abortions among female workers.
The toxicity of antimony to animals varies considerably depending on the compound used. No adverse effects have been associated with long-term exposure of rats to antimony trioxide. However, potassium antimony tartrate reduced the animals’ lifespan, and antimony was found to accumulate in the heart, liver, kidney and spleen. It also affected blood glucose and cholesterol concentrations.
Animal studies have shown that antimony can cross the placenta. It may cause sterility, fewer offspring, and foetal damage.
Studies using male and/or female rats have reported that inhalation of concentrates of antimony trioxide and antimony ore increased the incidence of lung tumours in females. In ingestion studies on rats and mice, antimony did not appear to cause tumours.
Trivalent and pentavalent antimony salts have demonstrated mutagenic activity in tests with bacteria. They also induced chromosome aberrations in cultured mammalian cells.
The International Agency for Research on Cancer has concluded that antimony trioxide is possibly carcinogenic to humans by the inhalation route (Group 2B, inadequate evidence in humans, sufficient evidence in animals); and antimony trisulfide is not classifiable as to its carcinogenicity to humans (Group 3, inadequate evidence in humans and limited evidence in animals) (IARC 1989).
Derivation of the guideline
The guideline value of 0.003 mg/L for antimony in drinking water was derived as follows:
where:
0.43 mg/kg body weight per day is the lowest effect level based on decreased lifespan and altered blood levels of glucose and cholesterol in a lifetime study using rats (Schroeder et al. 1970).
70 kg is the average weight of an adult.
0.1 is the proportion of total daily intake attributable to the consumption of water.
2 L/day is the average amount of water consumed by an adult.
500 is the safety factor in using the results of an animal study as a basis for human exposure (10 for interspecies variations, 10 for intraspecies variations and 5 because a lowest effect level was used instead of a no-effect level).
The WHO guideline value of 0.005 mg/L was derived from this calculation but rounded up.
References
APHA Method 3500-Sb Part B (1992). Antimony: Atomic Absorption Spectrophotometric Method. Standard Methods for the Examination of Water and Wastewater, 18th edition. American Public Health Association, Washington.
IARC (International Agency for Research on Cancer) (1989). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans: some organic solvents, resin monomers and related compounds, pigments and occupational exposures in paint manufacture and painting. World Health Organization, IARC, 47, Lyons.
Schroeder HA, Mitchener M, Nason AP (1970). Zirconium, niobium, antimony, vanadium and lead in rats: Lifeterm studies. Journal of Nutrition, 100:59–68.
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