Relationship between childhood blood lead levels and stature

The second National Health and Nutrition Examination Survey, 1976 to 1980, incorporated medical history, physical examination, anthropometric measurements, dietary information (24-hour recall and food frequency), laboratory tests, and radiographs. In linear regressions of adjusted data from 2,695 children aged 7 years and younger, 91% of the variance in height, 72% of the variance in weight, and 58% of the variance in chest circumference were explained by six variables: age, race, sex, blood lead level, total calories or protein, and hematocrit or transferrin saturation level. Variables that did not significantly improve the models predicting growth included family income, degree of urbanization, serum albumin, copper, iron, and zinc levels, dietary carbohydrate, fat, calcium, potassium, phosphorus, vitamin A, vitamin C, niacin, riboflavin, and thiamine. The highly significant correlation of blood lead level with growth does not contradict the established association of childhood deprivation with increased lead exposure and with nutritional deficiences known to enhance lead absorption. Blood lead level may also represent a composite marker for unidentified genetic, ethnic, environmental, and sociocultural variables, other than race, sex, and nutrition, that affect growth. However, the correlation of stature, particularly height, with blood lead levels in the range of 5 to 35 micrograms/dL is so statistically significant that it merits investigation in other surveys and consideration of the multiple biologic mechanisms by which low-level lead exposure could impair the growth of children.     

Synergistic effects of iron deficiency and lead exposure on blood lead levels in children

Background  

Lead poisoning is a well recognized environmental health problem in children. Independent association of iron deficiency and lead exposure with elevated blood lead level (BLL) has been reported. Whether iron deficiency in combination with chronic lead exposure increases BLL and susceptibility to its harmful effects in children needs to be elucidated.     

Slow, natural reduction in blood lead level after chelation therapy for lead poisoning in childhood

Lead poisoning is treated with chelating agents. We report the natural decline of blood lead (Pb-B) concentration after treatment(s) (1967 to 1972) in 74 patients whose maximal Pb-B level ranged from 100 to 471 micrograms/dL (4.83 to 22.73 mumol/L). These longitudinal data (range, nine to 17 years) disclose a predictable decrease in Pb-B levels after treatment that is independent of the maximal Pb-B level before therapy. The correlation between age in months and the logarithm of the Pb-B level was significant, and the equation defined by the regression line allows one to predict Pb-B levels at specific ages after chelation therapy. It is important to recognize the slow, natural decline of Pb-B levels after chelation therapy once the level is stable and below 70 micrograms/dL (3.38 mumol/L). Multiple repeated courses of calcium disodium edetate are unlikely to influence the natural decline of the Pb-B level in asymptomatic children.     

Association of amino levulinate dehydratase levels and ferrochelatase inhibition in childhood lead exposure

The basis for the clinical variation in response to lead exposure in children is not well understood. We studied selected children from a large lead screening program in whom elevation of red cell protoporphyrin concentration (a measure of inhibition of the enzyme ferrochelatase) was markedly above or below average for a given blood lead level. We then measured the activity of the enzyme amino levulinate dehydratase in 306 of these children, and found that ALA-d activity was lower in children with higher protoporphyrin elevation, independent of the effects of lead. This observation, coupled with reports in the literature of families with ALA-d deficiencies and elevated red cell protoporphyrin values, makes likely a genetic basis for some of the variation in susceptibility to lead. The mechanism by which the two effects are associated remains unknown.     

Effects of iron therapy on infant blood lead levels

OBJECTIVES: To determine the effects of iron therapy on blood lead levels in infants with mildly elevated lead levels and varied iron status. METHODS: Infants from a community-derived sample in Costa Rica were categorized into five groups. Group 1 had iron-deficiency anemia with hemoglobin levels 相似文献   

Community characteristics associated with elevated blood lead levels in children

OBJECTIVES: To identify community characteristics associated with children having elevated blood lead levels (> or = 10 micrograms/dL) and examine whether these characteristics can be used to identify children with elevated blood lead levels. PARTICIPANTS AND SETTING: A total of 20,296 children in Monroe County, New York (< 6 years old) who had blood lead testing in the first 12 months after statewide mandated reporting of blood lead tests began. DESIGN: A logistic regression analysis was conducted to examine the association of children's blood lead levels and community characteristics by using community characteristics of 653 census block groups. RESULTS: The following community level variables were associated with increased risk of elevated blood lead levels in children: residence within the city [odds ratio (OR), 2.0; 95% confidence interval (CI), 1.6, 2.7]; block groups with a higher proportion of individuals of Black race (OR, 1.6; CI, 1.4, 2.0); higher screening rate (OR, 1.9; CI, 1.6, 2.4); lower housing value (OR, 1.6; CI, 1.2, 2.0); housing built before 1950 (OR, 1.5; CI, 1.3, 1.8); higher population density (OR, 1.5; CI, 1.3, 1.8); higher rates of poverty (OR, 1.4; CI, 1.2, 1.8); lower percent of high school graduates (OR, 1.3; CI, 1.1, 1.6), and lower rates of owner-occupied housing (OR, 1.2; CI, 1.0, 1.4). Community characteristics were comparable with clinic-based individual risk assessment to identify children with elevated blood lead levels. CONCLUSIONS: These data demonstrate that community characteristics can be used to develop screening strategies to identify children who have elevated blood lead levels and shift our efforts toward identifying houses containing lead hazards before occupancy and before children are unduly exposed.     

Effects of elevated blood lead levels in preschool children in urban Vellore

Objectives

To study the burden and associated risk factors for elevated blood lead levels among pre-school children (15–24 months) in urban Vellore, and to study its effects on child cognition and anemia.

Design

An investigative study through Mal-ED cohort.

Setting

Eight adjacent urban slums in Vellore, Tamil Nadu.

Participants

251 babies recruited through Mal-ED Network.

Outcome measures

Blood lead levels using Graphite Furnace Atomic Absorption Spectrophotometry method at 15 and 24 mo; hemoglobin estimation by azidemethemoglobin method; cognitive levels using Bayley Scales of Infant Development III.

Results

Around 45% of children at 15 months and 46.4% at 24 months had elevated blood lead levels (>10 μg/dL). Among children who had elevated blood lead levels at 15 months, 69.2% (45/65) continued to have elevated levels at 24 months. After adjusting for potential confounders, children from houses having a piped drinking water supply and houses with mud or clay floors were at significantly higher risk of having elevated blood lead levels at 15 months. Thirty one percent (21/67) of the children with elevated blood lead levels had poor cognitive scores. Children with elevated blood lead levels at 15 months had higher risk (Adjusted OR 1.80; 95% CI 0.80–3.99) of having poorer cognitive scores at 24 months. More than half of the children (57%) were anemic at 15 months of age, and elevated blood lead levels were not significantly associated with anemia.

Conclusions

Elevated blood lead levels are common among preschool children living in urban slums of Vellore. Poorer conditions of the living environment are associated with elevated lead levels.     

Non-treatment of screened children with intermediate blood lead levels.

An aggressive screening and follow-up program for children at risk for lead poisoning was conducted by a nurse practitioner in a small family practice unit. Subsequent venous blood lead determinations untreated cases show the natural fall in lead level over 12 to 18 months. Many of these children would have been chelated by others, yet individualized, specific, personalized care by a nurse practitioner permitted monitoring without treatment even in persistently leaded environments. No chelation therapy was necessary until the third summer, when coincident with a long, hot, dry season, the city's abatement system because nonfunctional. Non-treatment requires close follow-up, a relatively small population, and cooperation from the city.     

Maximal steady state blood lactate levels in 11-year-old boys

To evaluate whether anaerobic threshold criteria evaluated in adults are pertinent to children, ten boys with a mean age of 11.2 years were investigated during treadmill running. Maximal running velocity was determined at stepwise increasing load, with determination of blood lactate following exercise. On the following days four runs each lasting 16 min were performed at a constant speed starting with a speed corresponding to about 70% of the maximal speed and increasing it during the next run in order to determine maximal steady state levels of blood lactate. Blood lactate was measured at the end of every 4 min period. From this date the anaerobic threshold was calculated. The correlation between anaerobic threshold values and maximal steady state levels of blood lactate was poor, however, a steady state of blood lactate was present at 4.6 mmol/l, whereas the mean anaerobic threshold value was determined at 2.6 mmol/l. In view of our results, the anaerobic threshold during increasing work does not correspond to the true anaerobic threshold, which can be assumed to occur at much higher lactate values. The meaning of the term anaerobic threshold is therefore to be questioned.     

Seasonality and trend in blood lead levels of New York State children

Background  

Environmental exposure to lead remains a significant health problem for children. The costs of lead exposure in children are estimated to be considerably more than other childhood diseases of environmental origin. While long-term trends in blood lead levels (BLLs) among children are declining, seasonal variation persists. Cross-sectional studies have found a peak in summer months. Part of this variation may be due to increased exposure to lead paint on window sills and through increased contact with soils containing lead during the summer. The current study represents the largest published population-based study on seasonality and trends in the BLLs of children to date. In addition, the results offer a comparison of recent data on seasonality of BLLs in New York State children, to studies conducted over the past three decades.