The Office of Environmental Health Hazard Assessment updated the public health goal for antimony in California drinking water in September 2016. The goal is for total antimony ion. The updated goal is 1 ppb, replacing the 1997 goal of 20 µg/L (20 ppb). The critical study is the 90-day oral rat study of Poon and co-workers, and the critical endpoint used for the point of departure is liver nuclear anisokaryosis.
Key numbers
Figures below are copied as printed. Units are not converted. Species are not merged.
| Analyte | What was reported | Value | Unit | Basis | Where |
|---|---|---|---|---|---|
| Sb | previous PHG (OEHHA, 1997) of 20 micrograms per liter (µg/L) or 20 parts per billion (ppb) | 20 µg/L | µg/L | drinking water | Summary, p. 6 |
| Sb | 20 parts per billion (ppb) | 20 ppb | ppb | drinking water | Summary, p. 6 |
| Sb | California’s maximum contaminant level (MCL) for antimony | 6 ppb | ppb | drinking water | Occurrence in Drinking Water, p. 8 |
| Sb | The detection limit for purposes of reporting is 6 ppb | 6 ppb | ppb | drinking water | Occurrence in Drinking Water, p. 8 |
| Sb | the federal antimony MCL of 6 ppb | 6 ppb | ppb | drinking water | Occurrence discussion of Westerhoff et al., p. 9 |
| Sb | US EPA maximum contaminant level goal (MCLG) for antimony of 6 ppb | 6 ppb | ppb | drinking water | Risk characterization, p. 30 |
| Sb | USEPA (IRIS) Oral RfD (1991) & MCL water guidance value 6 ppb | 6 ppb | ppb | drinking water | Table 5, p. 29 |
| Sb | WHO Guidelines for Drinking Water Quality (2003) water guidance value 20 ppb | 20 ppb | ppb | drinking water | Table 5, p. 29 |
| Sb | Health Canada Maximum Acceptable Concentration (2008) water guidance value 4 ppba | 4 ppb | ppb | drinking water | Table 5, p. 29 |
| Sb | the MAC was set at the practical quantitation level of 0.006 mg/L (6 ppb) | 0.006 mg/L | mg/L | drinking water | Table 5 footnote a, p. 29 |
| Sb | calculated maximum acceptable concentration (MAC) for antimony in drinking water is 0.004 mg/L (4 ppb) | 0.004 mg/L | mg/L | drinking water | Table 5 footnote a, p. 29 |
| Sb | LOAEL of 0.43 mg/kg-day | 0.43 | mg/kg-day | oral dose | Risk characterization, p. 30 |
| Sb | The updated PHG of 1 ppb | 1 ppb | ppb | drinking water | Summary, p. 6 |
| Sb | the updated Public Health Goal for antimony is 1 ppb | 1 ppb | ppb | drinking water | PHG derivation, p. 28 |
The structured evidence record for this source holds 21 copied values. The table above is the short set.
Methods (brief)
OEHHA modeled graded liver histopathology from the Poon et al. 90-day drinking-water study with a 10 percent benchmark response. The selected point of departure is the BMDL10 of 0.14 mg/kg-day from the Gamma model for liver nuclear anisokaryosis in male rats. A total uncertainty factor of 1,000 was applied (10 interspecies, 30 human variation, and square root of 10 for subchronic to lifetime). Relative source contribution 0.40 and a time-weighted lifetime drinking-water intake of 0.053 L/kg-day were used. The calculated concentration 1.1 µg/L was rounded to a public health goal of 1 ppb.
Evidence fitness
A California public health goal of 1 ppb for antimony as total antimony ion in drinking water, based on liver histopathological changes (liver nuclear anisokaryosis) in a 90-day rat drinking-water study. The document also states the California MCL, the federal MCL and MCLG, the WHO drinking-water guideline, and the Health Canada maximum acceptable concentration.
It does not report a new occurrence survey of antimony in bottled or tap water. Cited leaching and bottled-water studies are not re-extracted here. It does not set a certification threshold, and it does not separate a numeric inorganic-antimony species limit from total antimony ion.
Limitations
The public health goal is a non-mandatory goal and is not the enforceable maximum contaminant level. The critical study used highly soluble trivalent antimony potassium tartrate, which the document says may overestimate risk from the pentavalent form that predominates in oxic drinking water. The printed health-protective equation labels the acceptable daily dose as 0.14 µg/kg-day while the benchmark dose is 0.14 mg/kg-day divided by 1,000. Numeric limits from other jurisdictions in the comparison table are those agencies’ values as restated by OEHHA, not new measurements.
Related evidence
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