Comparison of biometric data of children with high and low levels of lead in the blood

Growth of infants' length, weight, head and arm circumferences in relation to low levels of blood lead measured serially

To determine whether levels of blood lead during gestation and infancy that are below the CDC action level of 10 microg/dl affect infant growth, we studied 211 disadvantaged mother-infant pairs from Albany, NY. Mothers' lead levels were low (second trimester chi = 2.8 microg/dl) as were infants' (chi = 3.3 microg/dl at 6 months; 6.4 microg/dl at 12 months). Multiple linear regression analyses showed that second trimester lead levels were related to reduced head circumference at 6 and 12 months. Infants of mothers with second trimester lead at or above the median (>or=3 microg/dl) exhibited negative associations between blood lead and head circumference at 6 and 12 months, and with weight-for-age, weight-for-length, and upper arm circumference at 6 months, but those below the median did not. Infants' 6-month lead level was related to head circumference at 12 months in the total sample, and in the subsample of infants whose blood lead was above the infants' 6-month blood lead median. Infants were also grouped by changes in their relative blood lead status, that is, above vs. below the median, from second trimester to 12 months of age. Infants whose lead levels changed from above to below the median were larger than infants whose lead levels went from below to above the median. The results suggest that lead may affect some dimensions of infant growth at levels below 10 microg/dl, but effects of lead levels less than 3 microg/dl are not evident in this sample.

Relationship between low blood lead levels and growth in children of white-collar civil servants in Korea

The study examined the relationship between low blood lead levels and the physical growth of children in Seoul, Korea. Data were collected from 108 children (62 boys, 46 girls) aged 5-13 years, and the mean of the blood lead levels was 2.4microg/100ml (SD=0.7). The data analyzed included the blood lead levels, height, total arm length, weight, body mass index (BMI), and father's level of education. We used four multiple linear regression models with height, total arm length, weight, and BMI as the dependent variables, and age, sex, father's level of education, and blood lead levels as independent variables. In the multiple linear regression analysis, we found statistically significant, negative associations of height (p<0.02) and total arm length (p<0.01) with blood lead levels, but no association between blood lead or weight and BMI. Our study suggests that low blood lead levels specifically influence children's physical growth.

Environmental lead exposure, maternal thyroid function, and childhood growth

Prenatal and early-life exposure to lead is hypothesized to have a range of adverse effects on childhood health. Drawing on data collected from a population-based prospective cohort study of a highly exposed town and a low exposed town in Kosovo, Yugoslavia we assessed whether elevated maternal blood lead (BPb) concentrations during pregnancy were associated with reduced childhood measures of attained height and BMI or growth rate, and whether the associations, if any, were mediated by maternal thyroid hormone concentration at mid-pregnancy. There was no association between blood lead levels and height or BMI in either town. However, increased maternal thyroid hormone was unexpectedly associated with reduced attained childhood height, and growth rate of height from 6.5 to 10 years, in the low-exposure town. We examine potential reasons for this unexpected inverse association.

Decrease in birth weight in relation to maternal bone-lead burden

OBJECTIVES

Birth weight predicts infant survival, growth, and development. Previous research suggests that low levels of fetal lead exposure, as estimated by umbilical cord blood-lead levels at birth, may have an adverse effect on birth weight. This report examines the relationship of lead levels in cord blood and maternal bone to birth weight.

METHODS

Umbilical cord and maternal venous blood samples and anthropometric and sociodemographic data were obtained at delivery and 1-month postpartum. Blood-lead levels were analyzed by atomic absorption spectrophotometry. Maternal tibia and patella lead levels were determined at 1-month postpartum with use of a spot-source 109Cd K-X-ray fluorescence instrument. The relationship between birth weight and lead burden was evaluated by multiple regression with control of known determinants of size at birth.

RESULTS

Data on all variables of interest were obtained for 272 mother-infant pairs. After adjustment for other determinants of birth weight, tibia lead was the only lead biomarker clearly related to birth weight. The decline in birth weight associated to increments in tibia lead was nonlinear and accelerated at the highest tibia lead quartile. In the upper quartile, neonates were on average, 156 grams lighter than those in the lowest quartile. Other significant birth weight predictors included maternal nutritional status, parity, education, gestational age, and smoking during pregnancy.

CONCLUSIONS

Our results indicate that bone-lead burden is inversely related to birth weight. Taken together with other research indicating that lead can mobilize from bone into plasma without detectable changes in whole blood lead, these findings suggest that bone lead might be a better biomarker than blood lead. Because lead remains in bone for years to decades, mobilization of bone lead during pregnancy may pose a significant fetal exposure with health consequences, long after maternal external lead exposure has declined.

Effects of lead on the somatic growth of children

Studies on the effects of lead on the somatic growth of children are limited and contradictory. The authors investigated the adverse effects of blood lead concentration on the somatic growth of primary-school-age children. In this study, there was a total of 522 children, aged 6-9 y, who resided in three areas of Greece (i.e., Loutraki, Lavrion, and Elefsina). The medical evaluation included medical history; physical examination; and measurements of height, head circumference, and chest circumference. The authors also evaluated dietary information, socioeconomic status, and height of parents. The authors conducted laboratory tests for hematological parameters and blood lead levels. The mean blood lead level was 12.3 microg/dl (standard deviation = 8.9 microg/dl), and levels ranged from 1.3 microg/dl to 51.2 microg/dl. There were negative monotonic relationships between growth parameters and blood lead levels, even after the authors allowed for confounding effects. An increase in blood lead level of 10 microg/dl was associated with a decrease of (a) 0.33 cm in head circumference (95% confidence interval = 0.12, 0.55; p = .002); (b) 0.86 cm in height (95% confidence interval = 0.14, 1.16; p = .020); and (c) 0.40 cm in chest circumference (95% confidence interval = -0.22, 1.02; p = .207). These findings led the authors to conclude that a decrease in growth in children may be associated with blood lead concentrations.

Perspectives on lead toxicity

Lead toxicity causes hematological, gastrointestinal, and neurological dysfunction in adults and children. Symptoms are usually noted with blood lead greater than 1.93 mumol/L. Severe or prolonged exposure may also cause chronic nephropathy, hypertension, and reproductive impairment. Lead inhibits enzymes; alters cellular calcium metabolism; stimulates synthesis of binding proteins in kidney, brain, and bone; and slows nerve conduction. Less severe exposure to lead, designated by blood lead levels of 0.48-0.96 mumol/L, has been implicated in poor pregnancy outcome, impaired neurobehavioral development, reduced stature in young children, and higher blood pressure in adults. Biochemical and systemic effects of high and low level lead toxicity are described. Dust, water, and paint chips are still major sources of lead but lead from folk remedies, cosmetics, food supplements, food preparation utensils, and improperly prepared infant formula has caused epidemic and sporadic severe lead toxicity. Screening for pediatric low level lead exposure requires measurement of blood lead.

Prenatal and preschool age lead exposure: relationship with size

This report examines possible adverse effects on size and growth associated with subclinical prenatal and preschool age lead exposure in an urban cohort followed prospectively from birth through early childhood. Measurements of weight, stature (length), and head circumference were obtained at birth and during five subsequent in-home assessments. Prenatal lead exposure was assessed by cord (n = 185) and maternal (n = 162) blood lead levels at delivery. Preschool blood lead samples were obtained at ages six months (n = 151), two years (n = 165), three years (n = 165), and four years, ten months (n = 164). Multivariate longitudinal analyses incorporating adjustment for covariates revealed no statistically significant adverse effects of prenatal lead exposure on either neonatal size or on subsequent growth through age four years, ten months. Similarly, no statistically significant adverse effects were found between the preschool lead indices derived from blood collected at or after age two years and ensuing size measurements. We also found no evidence for an interaction between pre- and postnatal lead exposure. A marginal inverse association was exhibited between blood lead at six months and subsequent measures of head circumference. Limitations in the implications of this result in the context of many nonsignificant tests were discussed.

Increased erythrocyte protoporphyrins and blood lead--a pilot study of childhood growth patterns

The National Health and Nutrition Survey 1976-1980 demonstrated the inverse association of blood lead 8-35 micrograms/dl (0.4-1.7 microM) with height and weight in 2680 children 1-7 yr old. Growth has not been examined. A retrospective pilot study was made of growth, 0-42 mo, for 54 children found to have erythrocyte protoporphyrins greater than 35 micrograms/dl (0.6 mM) at 12-23 mo. For 24/54, all blood leads were less than 30 micrograms/dl (1.2 microM), with a peak annual mean of 18.5 micrograms/dl (0.9 microM); for 30/54, mean blood lead was 46.7 micrograms/dl (2.2 microM) at 12-23 mo with all subsequent blood leads greater than or equal to 30 micrograms/dl (1.2 microM). In both groups the mean height and weight at birth were at the 25th percentile. The high-lead children had increased weight velocity at 15 mo of age and were heavier at 24 mo. Weight gain related to total caloric intake, supporting food consumption, and hand-to-mouth behavior as significant factors in an increased blood lead ages 9-24 mo. The monthly directional change of height and weight percentiles after 24 mo, however, showed a decreased frequency of upward shifts when blood lead was greater than or equal to 30 micrograms/dl. Although an early high food intake appears to contribute to high blood lead by increasing the intake of lead from food and mouthing, persistent increases in the high blood lead and erythrocyte protoporphyrins were associated with subsequent growth retardation.

Lead and osteoporosis: mobilization of lead from bone in postmenopausal women

Although it has been known that humans accumulate lead in bone, mineralized tissue has been considered primarily as a sequestering compartment and not as a site of toxic action for lead. However, experimental data indicate that bone lead can be released during conditions of demineralization, such as pregnancy and lactation. We have examined lead status in women, before and after menopause, using the NHANES II dataset compiled between 1976 and 1980. In 2981 black and white women there was a highly significant increase in both whole blood and calculated plasma lead concentration after menopause. The results indicate that bone lead is not an inert storage site for absorbed lead. Moreover, lead may interact with other factors in the course of postmenopausal osteoporosis, to aggravate the course of the disease, since lead is known to inhibit activation of vitamin D, uptake of dietary calcium, and several regulatory aspects of bone cell function. The consequences of this mobilization may also be of importance in assessing the risks of maternal lead exposure to fetal and infant health.

Lead and child development

A group of independent epidemiological studies shows that fetal exposure to levels of lead previously considered safe is linked to impairment of infant mental development.

Lead contact and poisoning in Barbados slaves: historical, chemical, and biological evidence

Lead contact and lead poisoning have received scant attention in discussions of early West Indian societies but are potentially important issues in considering the health and medical problems of blacks. Although our discussion focuses on Barbados, the West Indian historical literature strongly suggests that our general findings are applicable to other Caribbean areas and have implications for understanding some of the disabilities of early white populations as well. In this paper we also seek to illustrate how bioanthropological and chemical analyses of slave skeletal remains and historical data can complement one another in defining and investigating various dimensions of slave life.