Analysis of safety guidance value of urinary arsenic in population by using the data of urinary arsenic in the drinking water arsenic poisoning area from 2005 to 2014

Objective To study the urinary arsenic safety guideline value of a population for evaluating the arsenic exposure level in a certain population and providing evidence for the implementation of prevention and control measures in endemic arsenicosis area. Methods According to the data from the national high-arsenic drinking water sources screening in endemic arsenicosis area of drinking water type and quality supervision and inspection for water-improving project to decrease arsenic from 2005 to 2014, census data on arsenic poisoning in endemic arsenicosis area, data on surveillance of endemic arsenicosis, 10 722 people with detailed personal information, complete water arsenic exposure data and accurate urinary arsenic detection data were selected to be the research objects. The relationship between urinary arsenic and water arsenic was analyzed based on the surveillance data of 4 501 people from 2013 to 2014. The safety guidance value of urinary arsenic was determined based on the geometric mean value of urinary arsenic in people exposed to water arsenic in the range of (0.050 ± 0.005) mg/L, and verified using the data of 6 221 people from 2005 to 2012. Every time, a random sample of 2 000 people was taken as the verification sample, the sensitivity and specificity of the index for determining whether water arsenic exposure exceeded the standard were determined by area under the ROC curve (AUC), and a total of 10 sample tests was performed. Results When the water arsenic concentration was less than 0.01 mg/L, the correlation coefficient of water arsenic concentration with urinary arsenic concentration was 0.097 (P < 0.01); when the water arsenic concentration was more than 0.01 mg/L and less than 0.05 mg/L, the correlation coefficient of arsenic concentration with water arsenic concentration was 0.456 (P < 0.01); when the water arsenic concentration was more than 0.05 mg/L, the correlation coefficient of water arsenic concentration with urinary arsenic concentration was 0.630 (P < 0.01). With increase of water arsenic concentration, the concentration of urinary arsenic increased significantly, and the difference was statistically significant (χ2=2 337.956, P < 0.01). When water arsenic concentration was in the range of (0.050 ± 0.005) mg/L, the urinary arsenic geometric mean was 0.032 mg/L. AUC analysis of 10 random samples of 2 000 people showed that the geometric mean of urinary arsenic was 0.032 mg/L in the population, which can accurately distinguish whether the water arsenic level exceeded 0.05 mg/L, and the AUC value was higher than 0.94. And the sensitivity and specificity were achieved 0.898 and 0.844. Conclusions The geometric mean of urinary arsenic is 0.032 mg/L, which can be used as a safety guideline value for urinary arsenic in the population. When the geometric mean of urinary arsenic exceeds this value, the population may be exposed to high arsenic. Key words: Arsenic poisoning; Urine; Water