Changes in cadmium exposure among persons living in cadmium-contaminated areas in northwestern Thailand: a five-year follow-up

Abstract

Objective: To determine changes in cadmium exposure among persons aged 15 years and older who lived in the 12 cadmium-contaminated villages in northwestern Thailand.

Material and method: Urinary cadmium was measured among villagers in 2004. An exposure reduction campaign was conducted soon afterwards, and in 2009, urinary cadmium was measured among people living in the same villages. The survey participants were asked about their smoking status and consumption of rice grown locally in cadmium-contaminated areas. Both were the two main routes of cadmium exposure in these villages.

Results: Seven thousand six hundred ninety seven and 6748 persons participated in the first and second surveys, respectively. The proportion of current smokers was higher in the first survey (34.9%) than the second survey (31.5%). The proportion of persons who consumed rice grown locally decreased from 88.0% in the first survey to 50.5% in the second survey. Of persons who consumed rice grown locally, the proportion of those with urinary cadmium > or =2 microg/g creatinine increased from 55.5% in the first survey to 61.3% in the second survey. Of persons consuming rice purchased from other areas, the proportion of those with urinary cadmium > or =2 microg/g creatinine decreased from 46.7% in the first survey to 35.6% in the second survey. In both surveys, the adjusted odds ratio for increasing prevalence of high urinary cadmium associated with consumption of locally grown rice was greater than that for tobacco smoking.

Conclusion: Urinary excretion of cadmium significantly decreased after environmental cadmium exposure was reduced.