Decreased Glutathione Peroxidase Activities with Concomitant Increased Oxidized Glutathione Levels among Residents in an Arsenic Contaminated Community of Southern Thailand

Glutathione peroxidase (GPx) and glutathione are important antioxidants responsible for the scavenging of reactive oxygen species (ROS). It has been shown that changes in GPx activities and glutathione levels are associated with various diseases including toxic chemical related diseases and cancers. The study aimed to determine the levels of GPx activity and glutathione among residents in Ron Phibun district, an arsenicexposed area. Blood samples were obtained from 32 volunteers in the Thasala group, a nearby nonarsenic-exposed area and 36 residents in the Ron Phibun group. Red cell lysates were subjected to analysis of GPx activity and glutathione. The results showed that GPx activities were significantly decreased among study subjects from Ron Phibun (p < 0.05). Interestingly, oxidized glutathione (GSSG) levels were significantly increased compared with those from Thasala (p < 0.05). Total glutathione and reduced glutathione (GSH) levels were not different among the two groups. Mean values of GPx activities, total glutathione and GSH tended to decrease among high-exposure subjects compared to low-exposure subjects. This was concomitant with a slight increase in GSSG levels among highexposure subjects. The levels of GPx activities and GSSG may be early biomarkers for low levels of oxidative stress in a mining area affected with arsenic poisoning.