Environmental arsenic exposure and risk of diabetes type 2 in Ron Phibun subdistrict, Nakhon Si Thammarat Province, Thailand: unmatched and matched case-control studies.

BACKGROUND: There are inconsistent findings on associations between low-to-moderate level of arsenic in water and diabetes risk from previous epidemiological reports. In Ron Phibun subdistrict, Nakhon Si Thammarat Province, Thailand, a low level of arsenic exposure among population was observed and increased diabetes mellitus (DM) rate was identified. OBJECTIVES: We aimed to investigate the association between determinants (including low-level water arsenic exposure) of DM type 2 risk among residents of three villages of Ron Phibun subdistrict, Nakhon Si Thammarat Province. MATERIALS AND METHODS: Secondary data from two previous community based-studies, conducted in 2000 and 2008, were utilized. Data on independent variables relating to arsenic exposure and sociodemographic characteristics were taken from questionnaires and worksheets for health-risk screening. Water samples collected during household visit were sent for analysis of arsenic level at certified laboratories. Diabetes cases (N=185) were those who had been diagnosed with DM type 2. Two groups of controls, one unmatched to cases (n=200) and one pair matched on age and gender (n=200), were selected for analysis as unmatched and matched case-control studies, respectively. A multiple imputation technique was used to impute missing values of independent variables. Multivariable logistic regression models, with independent variables for arsenic exposure and sociodemographic characteristics, were constructed. The unmatched and matched data sets were analyzed using unconditional and conditional logistic analyses, respectively. RESULTS: Older age, body mass index (BMI), having a history of illness in siblings and parents, and drinking were associated with increased DM type 2 risk. We found no convincing association between DM type 2 risk and water arsenic concentration in either study. CONCLUSION: We did not observe meaningful association between diabetes risk and the low-to-moderate arsenic levels observed in this study. Further research is needed to confirm this finding in the study area and elsewhere in Thailand.

Laboratory case identification of arsenic in Ronpibul village, Thailand (2000-2002).

Ronpibul village dwellers in the southern part of Thailand have been exposed to arsenic in the water and the environment over three generations. Over the past decades, clean water supplies, utilization and consumption have been introduced to the area. The villagers still use and select rainwater to other forms of potable water. In 2000, the epidemiological survey by Siripitayakunkit (Siripitayakunkit, U. Survey of Chronic Arsenic Poisoning in Ronpiboon, Nakhon Si Thammarat, Thailand, 2000. Proc. 6th International Conference on the Biochemistry of Trace Elements, Guelph, Canada) showed prevalence rate at 24.7%, by using the skin lesion as selection criteria. In 2000-2002, attempt to initiate the local arsenic patient center, we investigated the population at risk in three villages. The laboratory analyses cover urine arsenic level, urine sugar screening and skin lesion classified by dermatologist. The result showed the prevalence of 5.99% of melanosis and 8.67% of hyperkeratosis, 3.84% of urine sugar > 100 mg/dL and 6.33% urine arsenic > 50 microg/g creatinine. There were low to negligible correlation between arsenic urine with urine sugar (r2 = 0.241) and arsenic urine with skin lesion (r2 = 0.058).