Factors affecting arsenic methylation capacity: an italian case

Chronic arsenic (As) exposure is a critical public health issue. The As metabolism can be influenced by many factors. The scientific literature identifies, in addition to the dosage of As exposure, a series of factors related with As methylation capacity, such as individual's ethnicity, age, sex, body mass index, lifestyle and dietray habits, and inherited genetic characteristics. We verified if these factors influence As metabolism in four italian areas affected by differen tsource (natural or anthropogenic) of As pollution. Univariate analyses were conducted on 267 subjects aged20-49. These subjects completed a questionnaire and provided a urine sample for As speciation. Primary Methylation Index (PMI) and Secondary Methylation Index (SMI) were calculated as indicators for As metabolic capacity. The limit of statistical significance was p<0.05. Factors investigated were derived from the administered questionnaire. Compared to women, men had as tatistically significant higher PMI average value and a lower SMI average value. Poeple who drank tap water had a higher PMI average value and a lower SMI average value compared to those who do not drink tap water. Subjects occupationally exposed to chemicals showed a lower PMI average value and a higher SMI average value compared to those not occupationally exposed. People who drank whole milk 2-3 times a week had a lower PMI average value compared to those who do not consume whole milk. These results confirm that As methylation is influenced by a variety of factors. In the studied population As methylation is more efficient in women than in men. Furthermore, As exposure through consumption of tap water can reduce the capacity of As methylation. It also seems that occupational exposure somehow enhances As methylation capacity. Some signals emerged for dietary habits and should be deepened. The results of our study include information on the role of As oxidative methylation to characterize As poisoning process in differently As-contaminated sites.