The influence of exposure to inorganic arsenic and other arsenic species on early renal impairment among young adults in Taiwan

Chronic kidney disease (CKD) poses a significant global public health challenge, with environmental toxins potentially contributing to its prevalence. In Taiwan, where arsenic (As) contamination is endemic in certain areas, assessing its impact on renal health is crucial due to the country's high rates of unexplained CKD. This cross-sectional study assessed associations between urinary As species and early renal impairment biomarkers-the microalbumin-to-creatinine ratio (ACR) and β2-microglobulin (B2MG)-in 248 young Taiwanese adults (aged 20-29 years). We measured urinary As species (including arsenite [As3+], arsenate [As5+], monomethylarsonic acid [MMA], and dimethylarsinic acid [DMA]) and early renal impairment biomarkers (urinary microalbumin and B2MG levels). Median concentrations of urinary As3+, As5+, MMA, DMA, inorganic As (iAs), and the sum of inorganic and methylated As species (iSumAs) were 1.43, 1.02, 3.79, 31.53, 2.82, and 39.22 μg/g creatinine (Cre.), respectively. We also evaluated the first methylation ratio (FMR) and the second methylation ratio (SMR). After adjusting for potential confounding factors, a multivariate linear regression showed significant associations between B2MG and urinary As5+ (β = 0.299, 95% confidence interval [CI]: 0.113-0.485) and iAs (β = 0.281, 95% CI: 0.061-0.502) concentrations. A generalized additive model revealed non-linear relationships among As5+, iAs, and B2MG concentrations. Moreover, there were elevated risks associated with the highest tertile of B2MG concentrations compared to the highest tertile of urinary As5+ (odds ratio [OR] = 2.366, 95% CI: 1.196-4.682), MMA (OR = 1.917, 95% CI: 1.002-3.666), DMA (OR = 1.952, 95% CI: 1.015-3.753), and iSumAs (OR = 2.302, 95% CI: 1.182-4.483). These results indicated that exposure to As was associated with early renal impairment, particularly evidenced by increased urinary B2MG concentrations.