A survey of antibiotic contamination in tap water and associated health risks in China

As a major country of producer and user of antibiotics, China is likely to have an increased risk of antibiotic contamination in tap water, but relevant data remain limited. We selected 78 tap water samples from 33 of 34 provincial-level administrative regions in China, determined 34 representative antibiotics and their four transformed species in tap water, and assessed the health risks by hazard quotient (HQ) and hazard index (HI) based on the ratio of estimated daily intake (EDI) to current human safety thresholds. A total of 13 antibiotics and four transformed species were detected in tap water, with an overall detection frequency of 92.3 % and a median concentration of 3.73 ηg/L. The top three most commonly detected antibiotics were roxithromycin (74.4 %), dehydrated erythromycin (60.3 %), and acetylated sulfamethoxazole (33.3 %). The highest contamination levels were observed in East China, South China, and Southwest China, while the lowest levels were found in Northeast China. Coastal areas showed higher levels of phenicol contamination, while non-coastal areas or regions with low per capita GDP tended to have higher detection frequencies of sulfonamides. The maximum summed EDI of all antibiotics ranged from 1.43 × 10−3 μg/kg/day to 8.03 × 10−3 μg/kg/day for infants, toddlers, children, teenagers, and adults, with all HQs and HIs based on toxicological or microbiological effect being below 4.0 × 10−3. These findings indicate an extensive antibiotic contamination in tap water in China, with regional and economic development-related differences, and a low health risk suggested based on current human safety thresholds.