Blood lead levels analysis

A multivariate analysis (Table XXV) shows the increased blood-lead level caused by the RSR smelter contribution and the traffic contribution to be 5.5 and 1.0, respectively. ... 

According to the investigators, the lack of association with lead rank indicated that the effect of lead was due to current rather than past lead exposure. The probability that a child was hyperactive increased significantly with increasing PbB levels (as PbB percentile rank within age group). The probability of speech impairment, however, was not related to blood lead levels. Linear regression analysis... 

Analysis of the unadjusted data showed that all postnatal blood lead levels were inversely associated with Full Scale IQ measured at age 10 however, only the associations involving PbB level at ages 10 years,... 

A later analysis (Emhart et al. 1987) related PbB levels obtained at delivery (maternal and cord blood) and at 6 months, 2 years, and 3 years of age to developmental tests (MDI, PDI, Kent Infant Development Scale [KID], and Stanford-Binet IQ) administered at 6 months, 1 year, 2 years, and 3 years of age, as appropriate. After controlling for covariates and confounding risk factors, the only significant associations of blood lead with concurrent or later development were an inverse association between maternal (but not cord) blood lead and MDI, PDI, and KID at 6 months, and a positive association between 6-month PbB and 6-month KID. The investigators concluded that, taken as a whole, the results of the 21 analyses of correlation between blood lead and developmental test scores were "reasonably consistent with what might be expected on the basis of sampling variability," that any association of blood lead level with measures of development was likely to be due to the dependence of both PbB and... 

An adverse effect of lead on pregnancy rate has been noted in some animal studies (Kennedy et al. 1975). Acute-duration gavage administration of 390 mg lead/kg/day as lead acetate to rats resulted in a sharp decrease in pregnancy rates. This effect was not noted at 39 mg lead/kg/day. The study limitations include a lack of measurement of blood lead levels and lack of statistical analysis of pregnancy incidence. A decrease in the number of implantations was noted in untreated female mice that were mated to males that had been treated with 141 mg/kg/day lead chloride in the drinking water for 3 months... 

After absorption, lead enters the blood, and 97% is taken up by red blood cells. Here, lead has a half-life of two to three weeks during which there is some redistribution to the liver and kidney, then excretion into bile or deposition in bone. After an initial, reversible, uptake into bone, lead in bone becomes incorporated into the hydroxyapatite crystalline structure. Because of this, past exposure to lead is possible to quantitate using X-ray analysis. It is also possible to detect lead exposure and possible poisoning from urine and blood analysis, and the amount in blood represents current exposure. However, as lead is taken up into the red blood cell, both the free blood lead level and that in the erythrocytes needs to be known. 

Cohen GJ, Ahrens WE Chronic lead poisoning a review of seven years experience at the Children s Hospital, District of Columbia. J Pediatr 54 271-284,1959 Conaway MR, Watemaux C, Allred E, et al Pre-natal blood lead levels and learning difficulties in children an analysis of non-randomly missing categorical data. Stat Med 11 799-811, 1992... 

Moore MR, Meredith PA, Goldberg A A retrospective analysis of blood-lead in mentally retarded children. Lancet 1 717-719, 1977 Munoz H, Romieu I, Palazuelos E, et al Blood lead level and neuro behavioral development among children living in Mexico City. Arch Environ Health 48 132-139, 1993... 

Abbreviations ALAD, delta-aminolevulinic acid dehydratase ANOVA, analysis of variance BLL, blood lead level Hgb, hemoglobm HCT, hematocrit ZPP, zinc protoporphyrin. 

Regardless of the method of analysis and the competence of the laboratory, different laboratories come out with somewhat different results for the same sample. Variations of up to 5 xg/dl between one laboratory and another are not considered unusual or problematic. This does mean, however, that if a child s blood lead level is being followed to see if it is responding... 

B) For each employee covered under paragraphs 0)(1)(i) or (II) of this section whose last blood sampling and analysis Indicated a blood lead level at or above 40 pg/dl, at least every two months. This frequency shall continue until two consecutive blood samples and analyses Indicate a blood lead level below 40 pg/dl and... 

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