Blood, teeth and hair: 3 different materials used to evaluate exposure to lead and cadmium in children living in an industrial zone

There is a general agreement that children are a population at increased risk with respect to lead and cadmium exposure and to adverse health effects resulting from increased exposure. Different biological indicators such as blood hair and teeth have been used to evaluate lead and cadmium exposure in humans. However, up to date, it has not been established which is the best indicator to provide an assessment of internal exposure. The aim of the present study was to examine the levels of lead and cadmium in hair, blood and teeth of children living from birth in an industrialized area near Modena. The relationship between these indicators of exposure and children characteristics such as sex, weight, height, blood pressure and smoking habits of parents was also examined. 142 children (71 males and 71 females) representing 20.8% of those aged 6-7 years living in Sassuolo (Modena) have been included in the study. The geometric means of lead in blood, hair and teeth were 11.2 micrograms/dl, 7.24 micrograms/g and 6.16 micrograms/g, respectively. Hair lead were significantly related to both blood and teeth values (r = 0.226, p = 0.007 and r = 0.186, p = 0.027, respectively). Mean cadmium concentrations were 0.47 mu/l in blood, 0.17 micrograms/g in hair and 47.9 ng/g in teeth and no significant correlation was observed between the three biological matrixes examined. Significant correlations were found between lead and cadmium in both hair (r = 0.427, p = 0.000) and teeth (r = 0.224, p = 0.007). In addition, for lead content in teeth, a significant difference between boys and girls was observed; females showed higher values than males (6.77 micrograms/g vs 5.61 micrograms/g; t = 2.23 p = 0.028). Taking into account the individual characteristics of children, a negative relationship was found between Pb levels in teeth and height (r = -0.217, p = 0.024). Systolic blood pressure values were positively associated to cadmium hair levels in males but not in females (r = 0.281; p = 0.053). From the results of the present study it appears that blood, hair and teeth provide different information to predict lead and cadmium exposure of children. Hair seem to be a useful global indicator of total environmental pollution.