Cadmium-exposed population in Mae Sot District, Tak Province: 1. Prevalence of high urinary cadmium levels in the adults.

BACKGROUND In Mae Sot District, Tak Province, Thailand, the paddy fields receiving irrigation from the two creeks and crops grown in the areas were found to contain markedly elevated cadmium levels during the surveys in 2001-2004. OBJECTIVE The present report carried out a survey in 2004 to determine urinary cadmium, a good index of excessive cadmium exposure and body burden, among the exposed residents aged 15 years and older in these contaminated areas. MATERIAL AND METHOD Morning urine samples were collected from the subjects and then kept frozen until cadmium analysis. Urinary cadmium was determined using the atomic absorption spectrometry and urinary creatinine was determined using a method of reaction with picric acid at alkaline pH and colorimetry. RESULTS Of the 7,697 persons surveyed, only 45.6% had urinary cadmium levels < 2 microg/g creatinine. About 4.9% were between 5 and 10 microg/g creatinine and 2.3% had cadmium concentrations > 10. The urinary cadmium level was greater among women than men and increased with increasing age. Smokers were more likely to have high urinary cadmium than non-smokers. Persons who mainly consumed rice grown locally in the contaminated areas had higher urinary cadmium than those who did not. CONCLUSION Persons who had high urinary cadmium levels and might have cadmium-induced toxic effects should be screened for early detection of chronic cadmium toxicity. Smoking cessation programs should be one component of preventive action beneficial for the study population. The production of rice and other crops for human consumption should be prohibited to prevent further accumulation of cadmium in the body of the exposed population.