Health Risk Assessment of Arsenic and Manganese Contamination in West Virginia's Public Water Systems

Abstract

This study examines arsenic (As) and manganese (Mn) contamination in West Virginia's public water systems, focusing on Community Water Systems (CWS) and Non-Transient Non-Community Water Systems (NTNCWS). The research addresses the critical public health issue of heavy metal exposure through drinking water, which can lead to various adverse health effects. Water sampling data from 2011 to 2023 were obtained from the West Virginia Department of Health and Human Resources and analyzed for As (n=305) and Mn (n=112) across the state. This study utilized the U.S. Environmental Protection Agency's risk assessment framework, calculating Average Daily Dose (ADD), Lifetime Average Daily Dose (LADD), Hazard Quotients (HQ), and Cancer Risk (CR) for various age groups under multiple (default, low and high) exposure scenarios. Socioeconomic factors were evaluated using county-level data and examined using univariate analysis. The dependent variables were log-transformed As and Mn concentrations, while the independent variables included median income, county districts, collection year, and water system type. The findings revealed significant geographic variations in As and Mn contamination across counties. Arsenic levels remained relatively stable from 2011 to 2022 (1.6-6.7 µg/L) but spiked dramatically in 2023 (60.17 µg/L). Manganese levels increased significantly from 2017, peaking at 889 µg/L in 2019. Several samples exceeded regulatory limits: 19 As samples surpassed the maximum contaminant level (MCL) of 10 µg/L, and 67 Mn samples exceeded the secondary maximum contaminant level (SMCL) of 50 µg/L. Arsenic levels were significantly influenced by the year of collection and its interaction with the geographic district. Manganese contamination was influenced by geographic district and its interaction with collection year. The study found no significant correlation between As or Mn concentration and median income (p = 0.704, p = 0.283, respectively), suggesting that environmental factors may have a stronger influence on contamination levels than socioeconomic factors. All exposure scenarios for As in both the community water system (CWS) and non-transient non-community water system (NTNCWS) showed hazard quotient (HQ) values greater than 1, indicating considerable non-cancer risks across all age groups. Manganese exposure presented considerable non-cancer risks, particularly for infants and young children. Cancer risk characterization revealed elevated lifetime cancer risks for As exposure, exceeding the threshold of 1 × 10⁻⁶ in most scenarios. The study confirms significant variations in As and Mn contamination between counties and reveals considerable cancer and non-cancer risks from exposure to these metals in drinking water among West Virginia residents. These findings highlight the urgent need for targeted interventions to improve water quality and reduce exposure to these contaminants, particularly in high-risk areas. Recommendations include implementing targeted interventions in high-risk counties, enhancing water quality monitoring and remediation efforts, conducting public awareness campaigns, considering stricter regulations on industrial activities, and investing in water treatment infrastructure and distribution systems.