Human hairs, nails, and urine as biomarker of human exposure related with heavy metals contaminated in drinking water in agricultural area

Abstract

Urine, hairs and nails were used as biomarkers to compare between the groundwater drinking group and the non-groundwater drinking group in intensively agricultural areas in Ubon Ratchathani province, Thailand. The shallow groundwater is acidic with average pH values of 5.28+1.15 and 5.16+4.19 in dry and wet seasons, respectively. The results showed an average drinking rate of approximately 4.21±2.73 L/day, which is twice as high as the standard. Due to the high drinking rate and groundwater contaminated with heavy metals (As, Cd, Pb, Hg), during the dry season, the results showed that 24.14 % of the groundwater drinking participants found As carcinogenic risk and 27.59 % found As non-carcinogenic risks as well as 13.79 % of the participants had a Pb non-carcinogenic risk. Similarly, during wet season, the results revealed that 17.24% of groundwater drinking persons found As carcinogenic risk and 18.97% found As non-carcinogenic risk as well as 36.21% of the participants found Pb non-carcinogenic risk. Interestingly, the concentrations of As, Cd, Pb, and Hg in urine, hairs and nails of the groundwater drinking group were significant higher than the other group. The average As concentration in the urine of the groundwater drinking participants was 36.97 µg/L exceeding the urine standard (35 µg/L), while the other group was 19.30 µg/L. The average concentrations of As, Cd, Pb and Hg in hairs of the groundwater drinking group were 0.091, 0.613, 18.26, and 87.27 ug/gH, respectively, while non-groundwater drinking group were 0.077, 0.076, 14.851 and 15.43 ug/gH. For nails, the average concentrations of the groundwater drinking group of As, Cd, Pb and Hg were 0.378, 0.192, 61.640, 2.281 ug/gN, while non-groundwater drinking group were 0.257, 0.150, 23.500, 1.030 ug/gN, respectively. Finally, the associated factor of odd ratio and binary logistic regression of As in urine found potential risk factor was the groundwater drinking (OR=43.50, 95%CI: 5.60-337.91, and ORadj=70.77, 95%CI: 7.86-634.83). For As in nails, potential risk factor also found the groundwater drinking (OR=2.99, 95%CI: 1.31-6.80, and ORadj=3.58, 95%CI: 1.28-10.01). As a result, this study suggested that groundwater should be avoided directly consume and should be treated especially before use as drinking water. For the future study, urine is suggested to be the biomarker related with daily exposure to As, Cd, Pb, and Hg. Furthermore, for long term exposure, nail is suggested for As, Cd, and Pb bio-monitoring, while hair is suggested to be the biomarker for Hg exposure.