Cadmium Exposure and Renal Function Biomarkers: A 10-Year Follow-Up of Thailand’s Tak Province Population

Abstract

Cadmium (Cd) is a toxic heavy metal that has been recognized as significant to environmental health. Thailand’s Tak Province, known for its historical mining and agricultural activities, has been identified as an area of high cadmium exposure. The objective of this investigation was to assess urinary cadmium (UCd), metallothionine in serum (B-MT-1), and kidney injured molecular-1 in urine (U-KIM-1). The target population and study area comprised individuals born between 1992–1999 in the zinc-mining areas of the Phatapadaeng, Mae Tao, and Mae Ku subdistricts of Mae Sot District, Tak Province, Thailand. The sample size was 122 participants and the criteria for inclusion were the individuals rechecked for UCd in 2016. The case definition included testing for UCd by ICP-MS, early renal dysfunction (U-KIM-1), amounts exceeding 0.20 µg/gCr, and environmental exposure to cadmium, indicated by B-MT-1 using the enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed using Pearson’s product-moment correlation coefficient (r), chi-square (χ2), and analysis of variance (ANOVA) at the 0.05 level of statistical significance to make inferences. The results indicate that 90.16% of the urine samples contained cadmium concentrations between 0.20 and 0.49 µg/gCr. The prevalence of MT-1 and KIM-1 in individuals aged 19–21 was 19.35% and 17.59%, respectively. We found that MT-1 was significantly higher among the residents of Phatadpadaeng, whereas KIM-1 was dominant among Mae Ku subdistrict participants. Females aged 15–18 and 19–21 had higher levels of MT-1 and KIM-1 compared to males in both age groups. The concentration of UCd was found to be higher among participants aged 15–18 and 19–21 years with UCd levels ranging between 0.20–0.49 µg/gCr-MT-1 and 0.50–0.80 µg/gCr-KIM-1. There was no correlation between age, gender, or region and MT-1 and KIM-1 detection. Menstruation is one of the risk factors for iron loss resulting in iron deficiency among teenage girls, and thus a source of cadmium bioavailability in the body. We, therefore, recommend that relevant authorities should focus on carrying out periodic surveillance among women aged 19 to 21 to identify those affected and subject them to treatment.