Abstract

Human arsenic (As) exposure was first identified in the Ron Phibun subdistrict, southern Thailand, three decades ago. Since then, the government and other organizations have worked to minimize the problem by providing households with safer sources of water for consumption. According to the most recent study conducted between 2000 and 2002, a tiny percentage of the population had elevated urine As concentrations. Afterward, this issue received little attention. The objectives of this study were to describe human As contamination in high- and low-contamination areas of the Ron Phibun subdistrict as measured by urinary As concentrations, to compare urinary As concentrations between participants from high- and low-contamination areas, and to identify factors associated with elevated urinary As concentrations in high- and low-contamination areas. The survey of residents of Ron Phibun who were 18 years or older, had lived in the subdistrict for at least six months, and accepted to participate was conducted. The overall sample size was 560: 280 from low-contamination areas and 280 from high-contamination areas. Urine samples were analyzed using inductively coupled plasma tandem mass spectrometry. The urinary As concentration was adjusted by the urinary creatinine level. The prevalence of elevated urinary As concentration (>50 μg/g creatinine) was 74.9% and 81.3% in high- and low-contamination areas, respectively (p-value, 0.086). The median urinary As concentration was 73.8 μg/g creatinine for high-contamination areas and 78.3 μg/g creatinine from low-contamination areas (p-value, 0.201). In high-contamination areas, participants who worked as farmers had a significantly higher urinary As concentrations. In low-contamination areas, having deep well water in households was related to a significantly higher urinary As concentrations. Residents of the Ron Phibun subdistrict continue to face an environmental health risk from As exposure in both historically low- and high-contamination areas. Agricultural operations may be additional sources of As contamination.