Objectives To assess the health risk of chronic phenol exposure to the residual pollution of sudden phenol water pollution incidents.

Methods Phenol residue pollution was detected by dot sampling, detection and evaluation. On the basis of data completeness review, four steps of health risk assessment were adopted, namely hazard identification, dose-response relationship assessment, exposure assessment and risk characterization. Chronic health risk was assessed for phenol residue sequestration.

Results Since the outbreak of water pollution in Zhenjiang occurred in 2012, a small amount of phenolic remained in the sediment and water in Zhenjiang section of the Yangtze River. Hazard identification found that the key end point of the hazard effect of chronic phenol exposure was that the oral exposure of phenol resulted a slowdown in the weight gain of pregnant mothers, and the corresponding reference dose of non-carcinogenic hazard effect was 0.3 mg/(kg·d). In lifetime exposure scenarios, the average daily external exposure of phenol to drinking water via mouth was estimated to be 6×10^-5 mg/(kg·d) and the increment of emergency exposure was 3×10^-5 mg/(kg·d) based on the arithmetic mean of phenol content. The average daily external exposure of phenol to drinking water via mouth was estimated to be 2.4×10^-4 mg/(kg·d) and the increment of emergency exposure was 2.1×10^-4 mg/(kg·d) based on the maximum of phenol content. Average daily exposure and increment of exposure were less than the reference doses of phenol through oral exposure, which resulted in weight gain slowdown of pregnant mothers. According to the arithmetic mean of phenol content, the health hazard index was 2×10^-4 and the increment of health hazard index was 1×10^-4; the estimated health hazard index based on the maximum phenol content was 8×10^-4 and the increment of health hazard index was 7×10^-4. The non-carcinogenic health risk of chronic phenol exposure and the increment of health risk caused by emergencies were acceptable.

Conclusions Phenol residue pollution can enter human body through drinking water. However, the non-carcinogenic health risks and the incremental health risks caused by emergencies of chronic phenol exposure are very low. This research method can be used as a reference for health risk assessment of residual pollution in similar water pollution emergencies.