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    ABSTRACT: Erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity, erythrocyte zinc protoporphyrin (ZPP)/heme ratio, and urinary coproporphyrin (UC) concentration have been employed as biological indicators of moderate-to high-level lead exposure, corresponding to blood levels in excess of 50 micrograms/dl, in human subjects. The comparative efficacy of these measures as indicators of lead exposure consistent with sustained lower blood lead levels has not been systematically evaluated. In the present studies, we examined the relative sensitivity and magnitude of response of these three bioindicators in rats during chronic exposure to 0, 100, or 1000 ppm lead as lead acetate in drinking water for up to 10 wk, followed by a 10-wk postexposure period, with weekly assessments, or during subchronic exposure to 0 or 1000 ppm lead as lead acetate in drinking water for 6 d, with daily assessments. Analysis of variance (ANOVA) was used to determine if the lead-treated rats differed from controls and to distinguish between dose groups with respect to the three biochemical indices of lead exposure. The data were normalized by conversion to Z scores in order to compare indicators with regard to magnitude of change in response to lead treatment. The order of sensitivity of each indicator was determined by considering the magnitude of the correlation coefficient (r) between the indicator and the blood lead concentration in each study. The indicators in order of decreasing sensitivity to lead in the chronic study were UC > ZPP/heme > ALAD. The indicators in order of decreasing magnitude of change in response to change in blood lead level were also UC > ZPP/heme > ALAD. None of the heme pathway parameters was judged a satisfactory substitute for direct blood lead measurement as an indicator of low-level lead exposure. However, urinary coproporphyrin appears most useful in this respect owing to highest sensitivity and magnitude of change relative to blood lead content and relatively low variation of mean coproporphyrin levels.
    Journal of Toxicology and Environmental Health 04/1995; 44(3):351-67. DOI:10.1080/15287399509531964 · 2.35 Impact Factor
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    ABSTRACT: Lead plays an important role in many industrial processes. Although highly useful to man, lead has various types of toxic effects. There is constantly growing evidence of a relationship between the induction of chromosome breaks and an increased risk of onset of cancer. However, available data about the possible genotoxic and carcinogenic action of lead are conflicting. In this report we present the results of studies on lead concentrations in blood and the respective micronucleus frequencies in peripheral blood lymphocytes from workers employed in the recycling of automotive batteries in the surroundings of Porto Alegre, Brazil. We observed that in the occupationally exposed group, both lead concentration in peripheral blood and micronucleus frequency in lymphocytes were significantly higher compared to control (Z=6.35, P<0.0001 and Z=4.47, P<0.0001). The nuclear division index (NDI) values were significantly higher in the control group than in the exposed group (Z=2.13, P=0.0330), indicating a possible effect of Pb on nuclear proliferation. We also detected a negative correlation between micronuclei and progression of nuclear division (tau=-0.312, P=0.0129). There were no changes in micronucleus frequency between smoking and non-smoking workers exposed to lead (Z=0.03, P=0.9790). The only difference found between the groups of smokers and non-smokers was with respect to NDI, whose values were significantly higher among non-smokers (Z=1.98, P=0.0481).
    Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 01/2005; 565(1):53-60. DOI:10.1016/j.mrgentox.2004.09.003 · 3.68 Impact Factor
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    ABSTRACT: To determine whether the concentration of lead in bone constitutes a biological marker that is more sensitive for chronic toxicity than blood lead levels. Survey. A construction trade union with members who engage in carpentry, demolition, and other construction activities. Members of the construction trade union. We measured blood pressure, serum creatinine, hematocrit, and hemoglobin. We measured blood lead by anodic stripping voltametry and used a cadmium 109 K x-ray fluorescence instrument to make in vivo measurements of lead in the tibia (a heavily cortical bone) and the patella (a heavily trabecular bone). Information was also collected on medical history, smoking, and alcohol ingestion. Bone lead levels in the patella were found to be significantly correlated with a decrease in hemoglobin and hematocrit, even after adjusting for age, blood lead, body mass index, cigarette smoking, and alcohol ingestion and removing outliers. Blood lead levels were low (mean = 0.40 mumol/L [8.3 micrograms/dL]) and were not correlated with either hemoglobin or hematocrit. In the final multivariate regression model that corrected for measurement error, an increase in patella bone lead level from the lowest to highest quintile in this study population (37 micrograms/g) was associated with a decrease in hemoglobin and hematocrit of 11 g/L (95% confidence interval [CI], 2.7 to 19.3 g/L) and 0.03 (95% CI, 0.01 to 0.05), respectively. We conclude that patella bone lead levels are associated with decreased hematocrit and hemoglobin levels despite the presence of low blood lead levels. This conclusion may reflect a subclinical effect of bone lead stores on hematopoiesis and is the first epidemiological evidence that bone lead may be an important biological marker of ongoing chronic toxicity.
    JAMA The Journal of the American Medical Association 12/1994; 272(19):1512-7. DOI:10.1001/jama.272.19.1512 · 35.29 Impact Factor
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