Cancer- and non-cancer risk assessment of chlorination by-products in indoor swimming pools in Shenzhen, China

Abstract

Background Trihalomethanes (THMs) generated in chlorinated pools have raised great concerns for potential genotoxic, carcinogenic and mutagenic features. The present study aimed to assess multi-exposure cancer and non-cancer risk of THMs in indoor swimming pools in Shenzhen, China. Methods Six representative indoor swimming pools located in west, central and east of Shenzhen were selected, with waters at 30 cm below and air at 1.2 m above water surface sampled. Headspace gas chromatography-electron capture detector (HSGC-ECD) was used to measure water THMs, and thermal desorption gas chromatography (TD-GC) was adopted to measure air THMs. Swimmer Exposure Assessment Model (SWIMODEL) recommended by USEPA was performed to assess the lifetime cancer and non-cancer risk of THMs. Results The median THMs in pool waters was 48.69 µg/L (IQR: 36.81–65.72), and 45.69 µg/m³ (IQR: 24.61–112.50) for ambient air, both with chloroform (TCM) and bromodichloromethane (BDCM) as predominant components. The daily THMs intake was 1.40E-02 µg/kg.d (range: 6.72E-03–3.96E-02), with estimated lifetime cancer risk 9.39E-07 (range: 3.59E-07–3.05E-06) and non-cancer risk 1.26E-03 (range: 6.21E-04–3.58E-03). Inhalation was major exposure route, accounting for 70.5% of total THMs intaking. Female swimmers had significantly higher cancer risk (P = 0.028) and non-cancer risk (P = 0.028) than male swimmers. Conclusions The estimated lifetime cancer risk of THMs in indoor swimming pools in Shenzhen was below the USEPA‘s regulatory threshold of 1.0E-06, and non-cancer risk was less than the unacceptable level of 1.0. The lifetime cancer- and non-cancer risk was acceptable for THMs in indoor swimming pools in Shenzhen, China.