This national survey collected 166 groundwater samples from wells used for drinking in rural China and screened 1,300 organic micropollutants and 25 metals. Gallium was detected in more than 90 percent of samples. The authors could not find a reference dose for gallium, so it was left out of the noncancer risk sums.
Key numbers
- Gallium, median to maximum: 8.5 to 89 µg/L, detection frequency above 90 percent (Results; the median-to-maximum label is stated on the first metal in the same list and applies to the list). n = 166.
- Reference doses could not be obtained for gallium, rubidium, thallium, and thorium, so those metals were excluded from the noncancer risk assessment (Health Risk Assessment).
- Samples were collected in July 2016, February 2017, and July 2017. Beijing, Shanghai, Zhejiang, Hong Kong, Macao, and Taiwan were not sampled (Methods).
Methods (brief)
Metals were measured by ICP-MS. Organic compounds were screened by GC-MS and LC-QTOF/MS. Risks used Monte Carlo simulation. Missing toxicity values were taken from databases or estimated by quantitative structure-activity models. Gallium had no reference dose from either route.
Evidence fitness
Supports a median and a maximum for gallium in drinking groundwater from one large rural Chinese survey, and the absence of a reference dose in the databases the authors searched. Does not support a health benchmark, a mean, or a lower percentile. The full distribution is in a supplementary table.
Limitations
One country and one water type. The main text does not give a mean, a minimum, or percentiles other than the median and the maximum.
Related evidence
Update history
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