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In several recent epidemiological studies blood lead levels (BLLs) even below the current CDC intervention level of 10 microg/dl have been associated with reduced neurocognitive capacities of children, with no clear evidence of a "safe" threshold. We analyzed the relationship between the BLLs and the neurocognitive capacities of 205 Sardinian students aged 11 to 15 years, using 2 tests of the Swedish Performance Evaluating System (SPES) and the full-scale Intelligence Quotient (IQ) derived from the Wechsler Intelligence Scale for Children (WISC). The studied population included 104 children (61 males and 43 females) living in Portoscuso, a town 2 Km far from a lead smelter (mean BLLs: 5.98 +/- 2.2; max 11.5 microg/dl), and 101 age-matched students (55 males and 46 females) living in Sant'Antioco, a town about 20 Km far from the same smelter (mean BLLs: 2.08 +/- 0.8; max 4.5 microg/dl). Subjects with BLLs above 4 microg/dl performed worse in the SPES tests and scored about 5.0 points less on the full-scale IQ compared to the students with lower BLLs. The adjusted regression coefficients derived from the multivariate analysis showed that higher BLLs were significantly associated with worse performances in the SPES tests and with reduced IQ (0.94 points for each microg/dl of BLL). This study confirms the potential neurotoxicity of low-levels of lead suggesting the need of lowering the actual CDC "limit of concern" for children to values lower than 4 microg/dl, improving at the same time the environmental primary prevention for limiting the lead exposure of subjects living near the lead smelter.

In several recent studies blood lead levels below 100 microg/L have been associated with reduced neurocognitive capacities and neurobehavioural performances in children, with no clear evidence of the lowest "safe" level not associated to adverse effects on the CNS. We analyzed blood lead concentration and the results of 5 neurocognitive tests, two derived from the Swedish Performance Evaluating System (SPES) and three from the Wechsler Intelligence Scale for Children-Revised (WISC-R), in 139 Sardinian adolescents living in Portoscuso, a town 2 Km far from a lead smelter, and in 72 age-matched students living in S. Antioco, a town about 15 Km far from the same smelter. The blood lead concentrations were lower than 100 microg/l in almost subjects, but, in average, significantly higher particularly among males, in the Portoscuso group compared to controls. The regression coefficients derived from the multivariate stepwise analysis, adjusted for the student's age and gender and for the educational and socio-economic level of parents, showed that reduced performances in neurocognitive test were significantly associated to increasing blood lead concentrations. According to previous our surveys in the same area and to the recent scientific literature on this topic, the present study suggests the need to further low the blood lead levels, considered by the U.S. CDC in 1991 as potentially "safe" for the children's CNS, to a threshold possibly < 50 microg/L.

Among 273 students (age 11-16 years) living in two small towns located respectively 2 (Portoscuso) and 15 kilometres (S. Antioco) far from the industrial area of Portovesme, the respiratory risk associated to cigarette smoking and environmental pollution was evaluated by the ISAAC questionnaire and standardized spirometry. The prevalence of parent's smoking was high in both groups (66.3% and 59.4%). Smoking during pregnancy was reported by 15% of mothers, without significant differences between the two schools. The prevalence of smokers among students was similar comparing the two groups (7% vs 6%). The prevalence of asthma in the whole population was significantly associated to skin positivity to common allergens, to the familiarity for asthma and to the environmental tobacco smoking, particularly if maternal. Spirometric values were significantly lower among students living in Portoscuso than among those of the S. Antioco school, with an evident interaction between the residential factor and the tobacco smoking, active and/or passive, in reducing the forced end- expiratory flows. Our results support the significant role of tobacco smoking, active and passive, particularly if derived from maternal smoking during pregnancy, in increasing the prevalence of respiratory disorders and lowering lung function in children. Living in Portoscuso, because of higher environmental exposure to airborne pollutants of industrial origin, has been shown as a relevant factor further lowering the lung function among the studied sample.

Several recent meta-analyses, although some inconsistencies between studies, provide evidence for subtle deficits in neurobehavioural tests being associated with average blood levels (PbB) between 350 and 600 microg/l and for significant correlations between impairments in some test results and increasing indices present andlor cumulative exposure to inorganic lead. In this study we assessed the relationship between blood lead level (PbB) and results of some neurobehavioural tests derived from the SPES battery and from the WAIS-R among a sample of 94 lead smelter workers (median PbB: 302 microg/l; range: 60-690 microg/l). The stepwise multiple regression analysis shows that, even after adjusting for age, education level, score in the vocabulary test and for alcohol and cigarette consumption, the rise of PbB above 300 microg/l was significantly associated with the rise in the number of errors and in the response time of the Symbol Digit test. No significant relationship between PbB and results of the other tests was observed after adjusting for the main confounding factors. Despite the small size of this study and the few number of neurobehavioural tests applied, our results are suggestive for suble potential neurotoxic effects of inorganic lead even at the present exposure levels found in the studied sample of smelter workers and support the ACGIH BEI and the SCOEL recommendation for a biological limit of 300 microg/l of PbB.

The effects of low-level lead exposure on children's intelligence quotient (IQ) were investigated in 64 Sardinian adolescents (13-16 years old). To estimate potential early adverse effects on the Central Nervous System (CNS) due to very low-level lead, the Intelligence Quotient (IQ) of adolescents with present blood lead concentrations (PbB) generally below 10 microg/dl was measured. We analyzed blood lead concentration and individual IQ of 32 Sardinian children living in Portoscuso, a town 2 Km far from a lead smelter, and of other 32 controls living in S. Antioco, a town about 15 Km far from the same smelter. The Wechsler Intelligence Scale for Children Revised (WISC-R) was administered. The relation between IQ and blood lead concentration was estimated by linear multivariate models adjusting for several potential confounders, such as the educational and socio-economic level of the parents. The blood lead concentration was in average significantly higher in the Portoscuso group compared to controls. The linear model applied to the total population studied (n 64) showed that the blood lead concentration was inversely and significantly associated with IQ, with an extrapolated decline of 1.29 points in total IQ for each microg/dl increase of lead blood concentration. According to the recent scientific literature on this topic, results of our pilot study suggest the need to further lower the blood lead concentration for children to a threshold significantly below 10 microg/dl, value till now considered "safe" for the children's CNS.

To estimate potential early adverse effects on the Central Nervous System (CNS) due to very low exposure to inorganic lead, the Intelligence Quotient (IQ) of adolescents with present blood lead concentrations (PhB) generally below 10 micrograms/dl was measured. We analyzed blood lead concentration and individual IQ of 32 Sardinian adolescents living in Portoscuso, a town 2 Km far from a lead smelter, and of other 32 controls living in S. Antioco, a town about 15 Km far from the same smelter. The Wechsler Intelligence Scale for Children Revised (WISC-R) was administered. The relation between IQ and blood lead concentration was estimated by linear multivariate models adjusting for several potential confounders, such as the educational and socio-economic level of the parents. The blood lead concentration was in average significantly higher in the Portoscuso group compared to controls. The linear model applied to the total population studied (n 64) showed that the blood lead concentration was inversely and significantly associated with IQ, with an extrapolated decline of 1.29 points in total IQ for each microgram/dl increase of blood concentration. According to the recent scientific literature on this topic, results of our pilot study suggest the need to further lower the definition of an elevated blood lead concentration for children to a threshold significantly below 10 micrograms/dl, value till now considered "safe" for the children's CNS.