Elemental carbon and lead content of fine particles from American and French cities of comparable size and industry, 1985

Thermal degradation of hexachlorobenzene in the presence of calcium oxide at 340-400 °C

Hexachlorobenzene (HCB) in the milligram range was co-heated with calcium oxide (CaO) powder in sealed glass ampoules at 340-400 °C. The heated samples were characterized and analyzed by Raman spectroscopy, elemental analysis, gas chromatography/mass spectrometry, ion chromatography, and thermal/optical carbon analysis. The degradation products of HCB were studied at different temperatures and heated times. The amorphous carbon was firstly quantitatively evaluated and was thought to be important fate of the C element of HCB. The yield of amorphous carbon in products increased with heating time, for samples treated for 8h at 340, 380 °C and 400 °C, the value were 17.5%, 34.8% and 50.2%, respectively. After identification of the dechlorination products, the HCB degradation on CaO at 340-400 °C was supposed to through dechlorination/polymerization pathway, which is induced by electron transfer, generate chloride ions and form high-molecular weight intermediates with significant levels of both hydrogen and chlorine, and finally form amorphous carbon. Higher temperature was beneficial for the dechlorination/polymerization efficiency. The results are helpful for clarifying the reaction mechanism for thermal degradation of chlorinated aromatics in alkaline matrices.

Lead exposure assessment from study near a lead-acid battery factory in China

The production of lead-acid battery in China covered about one-third of the world total output and there are more than 2000 lead-acid battery factories. They may cause the major environment lead pollution. Blood lead levels of several hundreds of residents were over 100 μg/L due to the waste discharges from a lead-acid battery factory in Heyuan, Guangdong province. This study aimed to find out the environmental lead sources, the human lead exposure pathways, and the amplitudes from a lead-acid battery factory. The study results showed that lead levels in soil, dust, tree leaves and human blood declined with the distances increased from the production site. Twenty nine of 32 participants had blood lead levels of over 100 μg/L with an exceptional high value of 639 μg/L for one child. This result suggested that the lead-acid battery production from this factory has caused the elevated lead levels in its neighboring environment and residents. Dust intake was the dominant exposure pathway for humans (over 90%). The lead levels found in adult and toddler (6.19 and 50.1 μg/kg/d, respectively) in the polluted area were far higher than the provisional tolerable weekly intake (PTWI) of 25 μg/kg body weight (translated into 3.5 μg/kg/d), which was established by the joint FAO/WHO Expert Committee. Blood lead levels within the family members were strongly correlated with the house dust lead levels. Our results in this study suggested that further studies in this area should be performed to assess human exposure and relevant human health risks from living close to lead-acid battery factories.

Exposure to environmental tobacco smoke in pregnancy and lead level in maternal blood at delivery

OBJECTIVES

The particular purpose of our study was to assess the impact of environmental tobacco smoke (ETS) on the individual variability of blood lead levels in pregnant women as earlier publications demonstrated the increased blood lead in smokers.

MATERIALS AND METHODS

The material consisted of 240 pregnant women who participated in a prospective cohort study on vulnerability of the fetus and infant to environmental hazards. The enrolment included only non-smoking women with singleton pregnancies between the ages of 18-35 years. Whole blood lead concentrations were determined using inductively coupled plasma mass spectrometry.

RESULTS

On average, blood-lead measured in pregnant women at delivery was low (GM = 1.7 microg/dL; 95% CI:1.6-1.8 microg/dL) and none of them showed levels above 4.0 microg/dL, but persons reporting exposure to ETS had significantly higher blood lead level (GM = 1.9 microg/dL; 95%CI:1.8-2.1 microg/dL) than those free from this exposure (GM = 1.6 microg/dL; 95%CI:1.5-1.7 microg/dL). In order to single out the effect of the ETS exposure from the confounding variables, we used the stepwise multivariate linear regression for log blood-lead in maternal blood as dependent variable and a set of independent variables, such as age, weight of women before pregnancy and their education level. The results of the analysis showed that all the independent variables included in the model explained 11% of total blood-lead variability among the study women. The strongest component of variance was attributed to ETS exposure (5%), age (3%), education level (2%) and weight (1%). Inclusion into the model of other variables, e.g., residence area and traffic intensity did not improve the proportion of explained variability.

CONCLUSIONS

The reason for higher levels of blood-lead in the ETS-exposed women may result from the fact that tobacco smoke contains lead. However, it is possible that inhaled tobacco smoke also increases the absorption of lead from particulate matter deposited in the bronchial tree.