Blood lead in children and associations with trace elements and sociodemographic factors.

BACKGROUND: No safe blood lead concentration in children has been identified. Lead can affect nearly every system in the body and is especially harmful to the developing central nervous system of children. The aim of this study is to analyze blood lead in a population of children and its association with sociodemographic variables, biochemical parameters, copper, iron, selenium and zinc. METHODS: We recruited 155 children (86 boys and 69 girls) with a mean age of 7.3 (SD:4.1). Blood lead and serum selenium concentrations were measured by electrothermal atomic absorption spectrometry. Serum copper and zinc concentrations were measured by flame atomic absorption spectrometry. Serum iron levels were determined by colorimetric assay. A risk exposure questionnaire for lead was administered to the participants. RESULTS: The median blood lead level was 1.1 (IQR 0.7-1.6) µg/dL. Regarding risk exposure factors, the youngest children (<2 years) who played outdoors presented a median blood lead concentration of 1.1 µg/dL IQR: 0.48-1.48, compared to the median of 0.3 µg/dL IQR:0.2-0.48 in the children who stated they played at home (p = 0.024). Significant differences were also found when taking into account those parents who smoked (median 1.3 IQR 0.8-1.9 µg/dL vs 0.9 IQR 0.5-1.4 µg/dL of non-smokers, p = 0.002). Children who drank tap water had higher blood lead levels (median 1.2 IQR 0.7-1.6 µg/dL) than those who drank bottled water (median 0.7 IQR 0.2-1.3 µg/dL p = 0.014). In addition, children whose mothers had not finished school had higher blood lead levels (median 1.7 IQR 1.2-2.3 µg/dL) than those whose mothers had finished school (median 1.2 IQR 0.7-1.7 µg/dL) and those whose mothers had gone to university (median 0.9 IQR 0.5-1.4 µg/dL) p = 0.034. In the multivariate lineal regression analysis we continue to observe the association between mother's higher level of education and lower blood levels (p = 0.04) and the interaction between age and outdoor play (p = 0.0145). CONCLUSIONS: In spite of the decline in blood lead concentrations, associated risk factors continue to exist in vulnerable populations such as children.

Relationship between serum selenium, sociodemographic variables, other trace elements and lipid profile in an adult Spanish population.

INTRODUCTION: Several studies have shown an inverse relationship between selenium status and cardiovascular health, although epidemiologic evidence yielded by the randomized trials did not find a beneficial effect of selenium administration. The aim of this study was to analyze the association between serum selenium levels and lipid profile adjusted by age, sex and other associated factors among a general adult population in Spain. MATERIALS AND METHODS: We recruited 372 hospital employee volunteers (60 men and 312 women) with a mean age of 47 (SD: 10.9), whom were given a standardized questionnaire. Serum selenium concentration was measured by electrothermal atomization atomic absorption spectrometry. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry. RESULTS: The mean of serum selenium was 79.5µg/L (SD: 11.7) with no sex-dependent differences. In the multivariate linear regression analysis, the associated factors with the mean levels of selenium were: age (ß=0.223; CI 95%: 0.101-0.345), p<0.001; widowhood (ß=-9.668; CI 95%: -17.234 to -2.102), p=0.012; calcium supplements (ß=3.949; CI 95%: 0.059-7.838), p=0.047; zinc (ß=0.126; CI 95%: 0.013-0.238), p=0.028 and glucose (ß=0.172; CI 95%: 0.062- 0.281), p=0.002; Participants with serum selenium≥79.5µg/L were 1.98 (OR=1.98; CI 95% 1.17-3.35; p=0.011) and 2.04 times (OR=2.04; CI 95% 1.06-3.97; p=0.034) more likely to have cholesterol ≥200mg/dL and LDL-c ≥100mg/dL respectively than those with serum selenium <79.5µg/L. CONCLUSIONS: Higher selenium was positively associated with increased total and LDL cholesterol but not with HDL-c and triglycerides. More studies are needed in order to confirm the lower serum selenium findings in widows.