Objective To examine association between multiple heavy metals exposure and development of three-yearold children and to provide evidence for preventing long-term effects of heavy metals exposure on children's health.
Methods Three-year-old children (n=461) in a county without heavy metal pollution of Jiangsu province were enrolled in the study. Inductively coupled plasma mass spectrometry (ICP-MS) was used to examine the concentrations of lead, mercury, and cadmium in spot urine samples. The development conditions of the participants were measured by physical examination (body height, body weight, head circumference, and chest circumference) and the Gesell Developmental Scale (intelligence). SPSS 16.0 was used to analyze the association between the exposure and the selected health effects.
Results The urinary concentrations of lead, mercury, and cadmium did not fit the normal distribution, and the median levels and the ranges were 2.64 μg/L (0.50-25.77 μg/L), 0.76 μg/L (0.10-9.51 μg/L), and 0.21 μg/L (0.02-2.62 μg/L), respectively. The median levels and the ranges of creatinine-corrected urinary le ad, mercury, and cadmium concentrations were 5.80 μg/gCr (0.80-91.51 μg/gCr), 1.86 μg/gCr (0.21-28.55 μg/gCr), and 0.47 μg/gCr (0.05-4.61 μg/gCr), respectively. The height and weight of both the boys and the girls were higher than the national recommended values, reflecting good development condition. Trichotomous subgroups were generated by the P25 and the P75 of concentrations of le ad, mercury and cadmium. The body height, weight, motor developmental quotient, adaptive behavior developmental quotient, lan guage developmental quotient, and individual-social behavior were significantly different among the lead trichotomous subgroups. The motor developmental quotient was significantly different among the mercury trichotomous subgroups. The body height, weight, motor developmental quotient, adaptive behavior developmental quotient, language developmental quotient, and individual-social behavior were significantly different among the cadmium trichotomous subgroups. The body height, weight, head circumference, motor developmental quotient, and individual-social behavior were significantly different among the lead, mercury, and cadmium combined trichotomous subgroups. When regrouping by>P95 of selected heavy metal exposure indicators as extremely high exposure and low exposure group, significant differences were found in the adaptive behavior developmental quotient for lead levels, and in the motor developmental quotient and the individual-social behavior for cadmium levels. With the help of multiple linear regression, the cadmium level was negatively associated with the body height.
Conclusion The burden of heavy metals of children in a county of Jiangsu province is in a stable range. Yet relationship between the level of heavy metals and children's growth is not confirmed.
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