Abstract:
This research aims to study the concentration of arsenic in the water supply and water consumption in the tin-distribution areas located in Surat Thani province during June-July 2013. And to assess human health risk from exposure to arsenic from 5 kinds of water supply produced from surface water, ground water, old mine water, hill water and shallow well water. Two exposure pathways, i.e., gastrointestinal indirectly (indirect ingestion) and skin (dermal contact) were evaluated for two groups consisting of children (aged 0-6 years) and adults. using the methodology of USEPA (1989). The concentrations of arsenic in water ranged from 0.001 - 0.185 mg/l. The maximum concentration which exceeded the water standard value was found in the old mine water. The concentrations of arsenic in surface water supply and the old mine water supply, were both below the water supply standard. The risk assessment found that the cancer risks of all water types, for children and adults were 1.20E-04 - 7.23E-03 and 4.58E-05 - 2.75E-03, respectively, which exceeded the acceptable threshold. As for non-cancer risks, these two groups were in the range 0.27 - 16.06 and 12.10 - 6.10, respectively, which also exceeded the acceptable threshold. The two risk categories are sorted by descending order as follows; water, shallow well water, hill water, ground water, old mine water and surface water. Route of exposure via the digestive indirectly posed a greater risk than the skin. The risk assessment indicated that, although the concentration of arsenic in the water supply was within the standard, the risks of total cancers and non-cancers were higher than the acceptable values. Therefore, in order to secure the health of consumers, the dangers of arsenic should be considered from the standard and health risk together. For risk management, there should inform these unacceptable risks to the agency who is responsible for taking care of villages water supply system to remove the concentration of arsenic in the water treatment process. As well as the people who use the water for their cooking should treat the water prior to reduce the concentration of arsenic.