Trace elements in hair of urban schoolboys: a diagnostic tool in environmental risk assessment.

Hair analysis may represent a means to quantify the relationship between human exposure to metal contaminationand the environmental conditions of workplaces or residence sites. Hair are stable and their composition does notchange over short time period. Furthermore, sampling procedure is very easy, requires no specific professionalskills, is painless and non-invasive. 334 hair samples were collected from Caucasian children 11-13 years old,of both genders, without colored or treated hair, living in several Sicilian towns characterized by differentgeochemical environments: urban (Palermo), volcanic (Etna), mining area (Antillo-Fiumedinisi), industrial site(Pace del Mela), uncontamined area (Mistretta). Our study was divided into two parts. The first part was addressedto establish accurate coverage intervals for a cohort of elements (Al, As, Ba, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb,Rb, Sb, Se, Sr, U, V and Zn).The obtained main results can be summarised as follows:a) the most abundant chemical elements were zinc and copper (Zn>Cu), with concentrations exceeding 10ug/g.Next, we found Al>Sr>Ba>Pb>Se, all greater than 1ug/g. The remaining elements were all below 1ug/g;b) mean concentrations of Al, Ba, Sr and Zn were significantly higher in girls’ hair and those of Cr, Li, Rb, Sb,and V higher in boys’ hair;c) the predominance of Ba, Sr and Zn in girls seems to be attributable to puberty, whereas the higher levels of Cr,Li, Rb, Sb, U and V in boys may reflect the longer time boys spend outdoors with respect to girls.d) Coverage intervals for each element were computed according to IUPAC criteria.The second part was intended to provide more information about hair analysis by examining the impact of lifeambient on the element concentrations in hair and evaluating whether differences exist among children residing indifferent places. Palermo represented the reference site. Data were analysed statistically with the STATISTICAprogram. Kolmogorov– Smirnov’s test, with a level of significance set at p <0.01, was used to verify the normalityof data distribution. ANOVA (general linear model, GLM) at p<0.001 was used to verify the statistical significanceof observed differences between genders. 0.95 central inter-fractile coverage intervals were computed withcoverage uncertainty at confidence level 0.95. At the moment, with respect to Palermo, the following similaritieswere confirmed for each site:• Zinc and copper are the most abundant elements, with Zn>Cu and both greater than 10ug/g.• Sr levels in girls were always higher than those in boys.Some differences could be also observed. It was found that the abundance order of elements having concentrationsgreater than 1ug/g, excluding Zn and Cu, differed significantly among the study sites:• Al>Sr>Ba>Pb at Palermo• Al>Sr>Pb>Ba at Antillo-Fiumedinisi (mineralized area)• Al>Sr>Ba at Mistretta (rural area; Pb levels lower than 1ug/gr)• Al>Mn>Sr>Pb at Nicolosi (volcanic area; Ba less than 1ug/gr)• Sr>Al>Pb>Ba at Pace del Mela (industrial area)Furthermore, when compared with the other sites, Nicolosi samples have the highest concentrations of sevenelements out of the 18 determined: Co, Cr, Cu, Li, Mn, Sb, V and Zn. Pace del Mela samples show the highestconcentrations of Cd, (Pb), and Sr; hair samples from the mineralized area (Antillo-Fiumedinisi) have the highestconcentrations of Al, As, (Pb). Mistretta and Palermo samples have respectively the highest concentrations ofBa-Ni-Rb-Se and Mo. The linear discriminant analysis allowed us to statistically distinguish groups according togeographical sites.