Objective To determine the concentrations of phenol endocrine-disrupting chemicals (PEDCs) in drinking water in Chengdu plain, China and to conduct an exposure assessment.

Methods A total of 24 municipal water supply plants from six cities in Chengdu plain were selected for collection of source water, finished water, and terminal water samples (each one sample in everyone plant) from July to November 2023. Solid-phase extraction and ultra-performance liquid chromatography-tandem mass spectrometry were used to determine the concentrations of 11 PEDCs. The exposure assessment of residual PEDCs in drinking water was conducted according to the method for exposure assessment of pollutants in drinking water in the Exposure Factors Handbook of Chinese Population. The health risks of PEDCs in drinking water to humans were evaluated using an estrogenic activity-associated risk model.

Results Eleven PEDCs were detected in drinking water in Chengdu plain, with a median total concentration (P₂₅, P₇₅) of 177 (49, 575) ng/L. There were three PEDCs with detection rates greater than 40%, including nonylphenol, bisphenol AF, and octylphenol. The total concentration of alkylphenols was significantly higher than that of bisphenols (Z=-9.15, P < 0.001). The highest detection rate and concentration were observed in nonylphenol in six cities, with the higher detection concentration in B, E, and F cities. The types of PEDCs with detection rates greater than 40% were the most in F city and the fewest in B city. There was a significant difference in the total concentration of PEDCs, the concentration of alkylphenols and the concentration of bisphenols among six cities (χ²=13.74, 13.99 and 15.82, P < 0.05). The median total concentration (P₂₅, P₇₅) of PEDCs was 538 (241, 1 329) ng/L in source water, 105 (38, 388) ng/L in finished water, and 79 (40, 166) ng/L in terminal water. There was a significant difference in the total concentration of alkylphenols, bisphenols, and PEDCs among different types of water sources (χ²=20.60-21.64, P < 0.05). The pairwise comparison results showed that the total concentrations of alkylphenols, bisphenols, and PEDCs in source water were significantly higher than those in finished water and terminal water, respectively (corrected P < 0.05). The exposure assessment analysis showed that the average daily exposure dose of PEDCs in different age and gender groups was 0.02-4.90 ng/(kg ·d), and the maximum exposure dose was 0.16-68.88 ng/(kg ·d). Girls aged 0- < 3 months had the highest average daily exposure dose for total PEDCs, alkylphenols, and bisphenols among all age and sex groups, which were 68.88, 68.85, and 0.40 ng/(kg ·d), respectively. The estrogenic activity-associated risk analysis of PEDCs showed that the estrogenic toxicity equivalent values of six PEDCs in terminal water were all much lower than 1 ng E2/L, indicating no risk to health.

Conclusion Trace amounts of PEDCs, at the concentration in ng/L, are detected in the drinking water of six cities in Chengdu plain. The exposure of bisphenols to drinking water by different age and sex groups is much lower than the threshold of 4 μg/(kg ·d) recommended by the European Food Safety Authority and relatively safe. At the same time, there is no estrogenic activity-associated health risk. However, further attention should be paid to nonylphenol, octylphenol, and bisphenol AF, which have high detection rates and concentrations outside the standards for drinking water quality.