Association of Urinary Cd, Cr, Mn, As and Cu among Children with Particulate Matter Exposure

Objectives To explore the association and influencing factors of cadmium, chromium, manganese, arsenic and copper in urine among children with metal and metalloid components in particulate matters exposure.

Methods The authors conducted a cross-sectional study and selected the school with better air quality which located the upward wind direction of the pollution source as the control group, and the school located the downward wind direction of the pollution source as the exposure group. Consequently, the authors enrolled 250 children who studied at boarding schools, and 94 and 156 schoolchildren from the control and exposed groups, respectively. The authers collected the daily mean concentrations of PM with aerodynamic diameters ≤ 10 μm (PM₁₀) and diameters ≤ 2.5 μm (PM_2.5), as well as nitrogen dioxide (NO₂) during the full year in environmental monitoring stations nearest to the two chosen schools. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the levels of urinary cadmium, chromium, manganese, arsenic and copper, and gas chromatography mass spectrometry was used to detect urinary cotinine level.

Results The concentrations of PM_2.5, PM₁₀ and NO₂ in the exposed areas were significantly higher than those in the control areas (Z values were -12.46, -16.98 and -21.68, respectively, P < 0.01). The levels of urinary cadmium and arsenic in the exposed group were significantly higher than those in the control group (t values were 4.45 and 11.26, respectively, P < 0.01), but the levels of urinary chromium, manganese and copper were lower than those in the control group (t values were -6.89, -2.18 and -5.72, respectively, P < 0.05). Stratified by gender, the authors found that the urinary cadmium, chromium, manganese, arsenic and copper among boys had significant differences in two groups (t values were 2.53, -6.71, -2.77, 8.21 and -4.21, respectively, P < 0.05), and urinary cadmium, chromium, arsenic and copper among girls had significant differences in two groups (t values were 3.98, -2.60, 7.51 and -4.11, respectively, P < 0.05). Stratified by BMI, the authors found that urinary cadmium, chromium, manganese, arsenic and copper levels among children with normal BMI had significant differences in two groups(t values were 4.24, -5.35, -2.00, 9.48 and -4.74, respectively, P < 0.05), and urinary chromium, arsenic and copper levels among overweight children had significant differences in two groups (t values were -5.04, 5.64 and -3.31, respectively, P < 0.05). Stratified by urinary cotinine, the authors found that among the children of undetermined cotinine, urinary cadmium, chromium, manganese, arsenic and copper levels had significant differences in two groups (t values were 3.08, -5.77, -2.67, 9.59 and -5.49, respectively, P < 0.05), but among children of determined cotinine, urinary cadmium, chromium and arsenic had significant differences in two groups (t values were 3.38, -3.56 and 5.62, respectively, P < 0.05).

Conclusions Metal and metalloid components in particulate matters exposure was positively correlated with increased children's urinary cadmium and arsenic. Gender might have an effect on urine manganese levels. Obesity might affect urine chromium, arsenic and copper, and tobacco exposure might affect urine cadmium, chromium and arsenic levels.