Trace Metal and Metalloid Profiles in Hair Samples from Children in the Oil-Producing Region of Kazakhstan.

Toxic elements are considered a significant threat to public health in oil-producing countries. Western Kazakhstan is experiencing serious environmental problems due to the development of the oil and gas industry. This study aimed to assess the concentrations of toxic trace elements-aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), mercury (Hg), and lead (Pb)-in the hair of children residing in Kazakhstan's oil and gas-producing region, and to evaluate the relationship between the concentration of toxic elements and the remoteness of their residence from oil and gas fields. A cross-sectional analysis was conducted involving 1595 school-aged children. Element levels in hair samples were quantified using inductively coupled plasma mass spectrometry (ICP-MS). The association between trace element concentrations and residential distance from oil and gas fields was examined across three distance-based groups and further analyzed through multiple linear regression. The highest concentration of Al = 4.824 μg/g and Hg = 0.096 μg/g was found in the hair of children living close to oil and gas fields (0-16 km). A decrease in levels of Al (-0.072 (CI: -0.109; -0.036)) and Hg (-0.293 (CI: -0.343; -0.243)) is associated with increasing distance from oil and gas fields. As, Cd, and Pb had the lowest median concentrations in the hair of children living near oil and gas fields (0.030, 0.010, and 0.122 µg/g, respectively). There is a tendency for levels of As, Cd, and Pb to increase with distance from the fields (0.064 (CI: 0.039; 0.089), 0.093 (CI: 0.045; 0.141), and 0.244 (CI: 0.202; 0.287), respectively). Our findings indicate the need for biomonitoring of toxic elements to determine long-term temporal trends in the influence of toxic trace elements on the health of the child population of Western Kazakhstan.