Lead and arsenic exposure from the environment among young children and health risk assessment at an abandoned mine in southern Thailand

Abstract

Background: Abandoned tin mining in Tamtalu sub-district, Bannangsta district, Yala province in southern Thailand has left the area contaminated with lead and arsenic. The objectives of the study were to assess the risk among the children of exposure to lead and arsenic from the environment and to determine the quantities of the toxic substances accumulated in the body by analyses of blood and hair samples.

Methods: This study focused on children from newborn to six years old. A total of 119 households were randomly sampled from 157 households having children. The parents were interviewed. Environmental and biological samples from Tamtalu sub-district were collected and analysed for lead and arsenic levels by inductively coupled plasma-optical emission spectrometry (ICP-OES) and graphite furnace atomic absorption spectrometry (AAS). Risk assessment was calculated using conventional equations of US Environmental Protection Agency (EPA).

Results: Environmental lead levels were found ranged from 0.223-721.200 mg/kg, <0.010-5.215 mg/kg, 0.150-1.155 mg/L and <0.010-0.011 mg/L in soil, vegetable, breast milk and drinking water samples, respectively.  Environmental arsenic levels ranged from 0.532-475.000 mg/kg.,<0.020-0.650 mg/kg, <0.020-0.540 mg/L and <0.020-0.098 mg/L in soil, vegetable, breast milk, and drinking water samples, respectively. The hazard indices of lead and arsenic exposure via oral route were 0.2 and 2.1, respectively. It’s mean that hazard from non- carcinogen from arsenic was unacceptable (>1).  The risk of arsenic as a carcinogen was 3 in 1000 people, suggesting that the risk was unacceptable. The data suggested that the risk was highest from exposure to soil than vegetables, drinking water and breast milk, respectively. Lead levels ranged from 0.093-43.882 µg/dL and 0.045-7.670 mg/kg in the blood and hair samples, respectively.  Arsenic levels in the hair samples ranged from <0.020-1.670 mg/kg.

Conclusions: The health of some of the young children appeared to be at risk from lead and arsenic exposure.  Risk management through reduction of the exposure is needed.