Age-stratified probabilistic cancer and noncancer inhalation risks from volatile organic compounds near a major petrochemical complex in Rayong, Thailand
Communities residing near petrochemical complexes are chronically exposed to complex volatile organic compound (VOC) mixtures, but routine surveillance is often restricted to limited sentinel panels, which may lead to the underestimation of true health risks. This study assessed age-stratified probabilistic carcinogenic and noncarcinogenic inhalation risks near the Map Ta Phut Industrial Estate, Thailand, the world’s eighth-largest petrochemical hub. During 2021–2023, six routinely monitored VOCs, namely, benzene, toluene, ethylbenzene, xylene, 1,3-butadiene, and vinyl chloride, were measured at two residential stations and one industrial fence-line station. An expanded 20-VOC panel was additionally analyzed at the fence-line station to capture broader industrial emissions. In this study, Thai-specific anthropometric data and the carcinogenic equivalence quotient framework were integrated into 10,000-iteration Monte Carlo simulations to estimate the excess lifetime cancer risk (ELCR) and hazard index (HI) for preschool children, school-aged children, adolescents, and adults. In addition, the annual number of VOC-attributable excess cancer cases in Rayong Province was also estimated. The mean ELCRs were low at the community stations (4.10 × 10 − 7 to 3.08 × 10 − 6 ) but increased markedly at the fence-line station (3.18 × 10 − 5 to 2.32 × 10 − 4 ) and increased further under the expanded 20-VOC panel (5.00 × 10 − 5 to 3.61 × 10 − 4 ). While the mean HI remained below 1.0 for the routine panel at all the stations, it exceeded 1.0 for all the age groups under the expanded 20-VOC panel (ranging from 2.04 to 4.83). Preschool children had the greatest noncarcinogenic burden, with a 95th -percentile HI of 10.8. Benzene and ethylbenzene were the main carcinogenic contributors at the two community stations, whereas vinyl chloride dominated both the carcinogenic and noncarcinogenic risks at the industrial fence line. The estimated number of adult VOC-attributable excess cancer cases increased from 2.79 in 2015 to 3.15 in 2023, accounting for 0.36% of the regional cancer burden. Limited routine VOC monitoring may substantially underestimate petrochemical-related carcinogenic and noncarcinogenic risks. Age-stratified probabilistic assessment using an expanded VOC panel revealed substantial fence-line risks driven by specialty monomers, highlighting preschool children as a priority population for strengthened surveillance and site-specific risk management.