Blood lead effects

Dose (blood lead)-effect data are available in the study by Fowler et al. (1980). Rats exposed to lead acetate in the drinking water through the dams during gestation and lactation and then directly until 9 months of age had the following external exposures (ppm lead), internal exposures ( pg lead/dL in blood), and renal effects 0 ppm (controls), 5 pg/dL, no lesions 0.5 ppm, 4.5 pg/dL, no lesions 5 ppm,... 

Marcus AH, Schwartz J. 1987. Dose-response curves for erythrocyte protoporphyrin vs blood lead Effects of iron status. Environ Res 44 221-227. 

Marcus, A.H., Schwartz, J., 1987. Dose—response curves for erythrocyte protoporphyrin vs. blood lead effects of iron status. Environ. Res. 44, 221—227. 

The skin s mechanism of heat conservation involves its very complex circulatory system [2,3]. To conserve heat, blood is diverted away from the skin s periphery by way of the arteriovenous anastomoses. The ex-ternalmost circulation of the blood is effectively shut down, leading to a characteristic blanching of the skin in fair-skinned individuals. Less heat is irradiated and convectively passed into the atmosphere. Furry mammals have yet another mechanism to conserve body heat. Each tiny arrector pilorum stands its hair up straight, adding appreciable thickness to the insulating air layer entrapped in the fur, reducing heat loss. 

Effects in Humans Based on Blood Lead (PbB) Levels... 

Duration of exposure System Effect Blood lead levels at which effect was observed (ug/dL) Reference... 

NS (general population) Cardiovascular Increased systolic pressure by 1-2 mm Hg and increased diastolic pressure by 1.4 mm Hg with every doubling in blood lead level effect most prominent in middle-aged white men 7-38 Coate and Fowles 1989 Harlan 1988 Harlan et al. 1988 Landis and Flegal 1988 Pirkle et al. 1985 Schwartz 1988 Proctor et al. 1996... 

NS (general population) Neurological No correlation between blood lead levels and permanent effects on neurobehavioral development in children 10-15 Bellinger et al. 1989a Cooney et al. 1989a Dietrich et al. 1987a Emhart and Greene 1990 Harvey et al. 1984,1988 Lansdown et al. 1986 McBride et al. 1982 McMichael et al. 1986 Pocock et al. 1989 Smith et al. 1983 Winneke et al. 1984... 

No effects of lead on thyroid function have been found in children. Thirty-six male and 32 female children ranging in age from 11 months to 7 years (median age of 25 months) took part in a study of the effects of lead exposure on thyroid function in inner city children (Siegel et al. 1989). Blood lead levels,... 

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... 

The literature on the neurobehavioral effects of oral exposure to lead in animals is extensive. Only those studies considered key to clarifying human health issues will be presented here. High levels of exposure to lead produce encephalopathy in several species, but blood lead data for this effect are generally not available. 

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... 

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