Preliminary investigation on residents' thallium exposure after thallium pollution in a river in southeast Guangxi Zhuang Autonomous Region, China

Objective To investigate thallium levels in well water, soil, and food products from land, as well as residents of a village along a river of thallium pollution in southeast Guangxi Zhuang Autonomous Region, China after thallium pollution three years later, and to evaluate the health risk of local residents.

Methods In 2016, a village along a river where a thallium pollution event had occurred in 2013 were selected as the polluted area, and a natural village along the upstream of the polluted river section were selected as the control area. Well water samples, soil samples, land-produced food samples, and urine samples from local residents aged between 18 and 75 years were collected to measure thallium levels by ICP-MS.

Results Compared with the control area, the polluted area had a significantly higher thallium level in well water (median: not detected vs 0.290 μg/L, z=-6.51, P < 0.01), a significantly lower qualified rate of thallium in well water (100.0% vs 24.6%, χ²=42.48, P < 0.01), a significantly higher thallium level in soil (median: 0.595 vs 0.755 mg/kg, z=-2.02, P < 0.05), and a significantly higher thallium level in food (median: 0.250 vs 1.861 μg/kg, z=-4.14, P < 0.01). There was no significant difference in urinary thallium content among residents in the polluted area and those in the control area (geometric mean: 0.70 vs 0.67 μg/g creatinine, F=1.18, P>0.05).

Conclusion Residents in the polluted area are exposed to thallium to a certain extent, but their urinary thallium level is similar to that of residents in the control area.