Objectives To evaluate the urinary gallium (Ga), indium(In) and thallium (Tl) level of general people in China and to analyze their population distribution.

Methods A total of 18 120 subjects from general population aged 6～60 years were recruited from 24 districts in 8 provinces of eastern, central and western China from 2009 to 2010 by cluster random sampling method, and their urinary samples were collected. A questionnaire survey method was used to collect the information on their living environment and health condition. Inductively coupled plasma mass spectrometry (ICP-MS) was applied to determine Ga, In and Tl level in urine samples, and the distribution of urinary Ga, In and Tl in different ages and genders was then analyzed.

Results In general, the 50^th percentiles of urinary Ga was 0.08 μg/L (< LOD), and the 95^th percentile was 1.72 μg/L. The 50^th percentile of urinary Indium in male and female were all 0.08 μg/L (< LOD). The detection rate of urinary Ga in male and female were 26.5% and 21.6% respectively (χ²=43.478, P < 0.01), The 50^th percentile of urinary indium was 0.03 μg/L (< LOD), and the 95^th percentile was 0.61 μg/L. The 50^th percentile of urinary indium in males and females were all 0.03 μg/L (< LOD). The detection rate of urinary indium in male and female were 16.3% and 18.1%(χ²=5.234, P < 0.05)respectively. The geometric mean (GM) of urinary thallium was (0.17±0.01) μg/L, the 50^th percentile was 0.27 μg/L and the 95^th percentile was 1.37 μg/L. The geometric mean (GM) of urinary Tl in male and female were (0.18±0.01) μg/L and (0.16±0.01) μg/L (Z=4.86, P < 0.01). The detection rate of urinary thallium were 84.0% and 83.0% for male and female (χ²=2.577, P>0.05) respectively.

Conclusions The concentrations and distribution of urinary gallium, indium and thallium in the general population in China reported in this study provided a basic data and evidence for further studies on biological monitoring gallium, indium and thallium in Chinese population.