Factors underlying urinary arsenic levels in a population residing close to a coastal heavy-industrial area in southern Taiwan

Abstract

The public in the southwestern Taiwan’s Kaohsiung City expressed concern over risk of arsenic (As) to people living in six of that city’s townships nearby a coastal area with heavy industry. To investigate, we first analyzed urinary total As levels in 539 subjects administered Taiwan’s Nutrition and Health Survey, a nationwide survey of nutritional status 2005-2008 (NAHSIT 2005-8). We found the top three highest median urinary total As levels in residents from Penghu island (136.93 µg/L, n = 24), the upper northern region of Taiwan (78.54 µg/L, n = 69), and the southwestern region of Taiwan (71.87 µg/L, n = 36). We then measured total urinary As levels in 1,801 and 1,927 voluntary residents of the above-mentioned six townships in 2016 and 2018, respectively, and compared with those with people residing in the top three highest total As levels of NAHSIT 2005-8. Median urinary As levels were 84.6 µg/L in 2016 and 72.5 µg/L in 2018, similar to those in southwestern region of Taiwan, but far below those in Penghu island (p <0.05). Finally, in 2020, we interviewed 116 healthy and voluntary residents from the same six townships and collected one-spot urine samples to analyze total inorganic-related As (TiAs), a summation of As3+, As5+, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). Median urinary TiAs in participants consuming seafood two days before urine sampling (n=15) was 24.0 µg/L, significantly higher than those not consuming seafood then (median: 20.5 µg/L, n=101, p=0.029). The results remained significant after adjusting for other covariates (p = 0.028). These findings suggest that seafood consumption is probably the main source of urinary total As and TiAs in people residing close to that coastal heavy industrial area of southern Taiwan. A future intervention study (dietary control) could be conducted to re-confirm our findings.