The evidence that lead increases the risk for spontaneous abortion

BACKGROUND: Reports from a period spanning more than a century, and covering occupationally exposed women in several countries, support an increase in pregnancy loss from high maternal lead exposures. Nevertheless, most studies conducted among populations with low/moderate exposures have provided little evidence of an association with pregnancy loss, or in particular, spontaneous abortions. METHODS: A critique of these low/moderate level studies reveals small sample sizes, problems in definition or ascertainment of outcome, lack of control for confounding, and/or deficiencies in the exposure assessment. For estimating exposure, either an ecologic measure was used, or individual biologic specimens were taken but attention was not paid to the timing of measurement of lead levels in these samples. A prospective study that overcame most of the deficiencies of previous studies enrolled pregnant women in Mexico City with low-to-moderate-level lead exposures, collected blood specimens during their first trimester, and ascertained spontaneous abortions by week 20. A key design element of this study was the use of incidence-density-matched controls in order to achieve comparable opportunity for the outcome and comparable timing of exposure measurements. The latter is especially important because blood lead levels are altered by pregnancy. RESULTS: In the prospective Mexico City Study, a striking dose-response relation between blood lead and risk of spontaneous abortion was found: the odds ratio for spontaneous abortion was 1.8 (95% confidence interval = 1.1-3.1) for every 5 microg/dL increase in blood lead. CONCLUSIONS: Low-to-moderate lead exposures may increase the risk for spontaneous abortion at exposures comparable to U.S. general population levels during the 1970s and to many populations worldwide today; these are far lower than exposures encountered in some occupations. Further research is needed to confirm the association, to delineate the role of maternal vs. paternal exposures, and to assess increases in menstrual variability as an explanation for this finding.     

Inadequate prenatal care and elevated blood lead levels among children born in Providence, Rhode Island: a population-based study

OBJECTIVE: This study was conducted to determine whether children born to mothers receiving inadequate prenatal care are at an increased risk for having an elevated blood lead level during early childhood. METHODS: The authors conducted a population-based study of children born in Providence, Rhode Island, from 1997 to 2001 whose mothers had received adequate, intermediate, or inadequate prenatal care. The children's blood lead levels were compared between groups using bivariate and logistic regression. To understand the regulatory implications and public health impact of changing the definition of an elevated blood lead level, "elevated" was defined as 5 microg/dL, 10 microg/dL, and 15 microg/dL. RESULTS: Children born to mothers who received inadequate prenatal care were at an elevated risk for having an elevated blood lead level later in life. This relationship remained statistically significant for each definition of elevated blood lead level and after controlling for other socio-economic status measures and birthweight (at 5 microg/dL, odds ratio [OR] = 1.36, 95% confidence interval [CI] 1.09, 1.68, p = 0.006; at 10 microg/dL, OR = 1.68, 95% CI 1.26, 2.24, p < 0.0004; at 15 microg/dL, OR = 1.83, 95% CI 1.10, 3.04, p = 0.019) represent an opportune moment to identify expectant mothers living in lead-contaminated environments. CONCLUSIONS: Results suggest that conducting lead screening as a regular part of prenatal care provision could help identify women possibly experiencing ongoing lead exposure and help reduce or prevent exposures to their offspring.     

Early pregnancy blood lead and spontaneous abortion

Although evidence tends to suggest that high levels of lead exposure increase the risk of spontaneous abortion, we do not yet know whether moderate- to low-level exposure elevates risk. Among 351 women (aged 16 to 35 years, with single pregnancies) who were registered for a longitudinal study, 15 (4.3%) women experienced spontaneous abortion after the 12th week of gestation and before the 20th week. We collected participants' blood samples during the first trimester of pregnancy (8-12 weeks) for lead measurement by inductively coupled plasma-mass spectrometry. Mean ± standard deviation of blood lead was 3.8 ± 2.0 μg/dl (range 1.0-20.5 μg/dl) with a geometric mean of 3.5 μg/dl. Mean blood lead concentrations did not differ significantly between spontaneous abortion cases and ongoing pregnancies (3.51 ± 1.42 and 3.83 ± 1.99 μg/dl, respectively). The findings suggest that in apparently healthy women, low blood lead levels (mean < 5 μg/dl) measured in early pregnancy may not be a risk factor for spontaneous abortion.     

Levels of lead in breast milk and their relation to maternal blood and bone lead levels at one month postpartum

Despite the many well-recognized benefits of breast-feeding for both mothers and infants, detectable levels of lead in breast milk have been documented in population studies of women with no current environmental or occupational exposures. Mobilization of maternal bone lead stores has been suggested as a potential endogenous source of lead in breast milk. We measured lead in breast milk to quantify the relation between maternal blood and bone lead levels and breast-feeding status (exclusive vs. partial) among 310 lactating women in Mexico City, Mexico, at 1 month postpartum. Umbilical cord and maternal blood samples were collected at delivery. Maternal breast milk, blood, and bone lead levels were obtained at 1 month postpartum. Levels of lead in breast milk ranged from 0.21 to 8.02 microg/L (ppb), with a geometric mean (GM) of 1.1 microg/L; blood lead ranged from 1.8 to 29.9 microg/dL (GM = 8.4 microg/dL); bone lead ranged from < 1 to 67.2 microg/g bone mineral (patella) and from < 1 to 76.6 microg/g bone mineral (tibia) at 1 month postpartum. Breast milk lead was significantly correlated with umbilical cord lead [Spearman correlation coefficient (rS) = 0.36, p < 0.0001] and maternal blood lead (rS= 0.38, p < 0.0001) at delivery and with maternal blood lead (rS = 0.42, p < 0.0001) and patella lead (rS= 0.15, p < 0.01) at 1 month postpartum. Mother's age, years living in Mexico City, and use of lead-glazed ceramics, all predictive of cumulative lead exposure, were not significant predictors of breast milk lead levels. Adjusting for parity, daily dietary calcium intake (milligrams), infant weight change (grams), and breast-feeding status (exclusive or partial lactation), the estimated effect of an interquartile range (IQR) increase in blood lead (5.0 microg/dL) was associated with a 33% increase in breast milk lead [95% confidence interval (CI), 24 to 43%], whereas an IQR increase in patella lead (20 microg/g) was associated with a 14% increase in breast milk lead (95% CI, 5 to 25%). An IQR increase in tibia lead (12.0 microg/g) was associated with a 5% increase in breast milk lead (95% CI, -3% to 14%). Our results indicate that even among a population of women with relatively high lifetime exposure to lead, levels of lead in breast milk are low, influenced both by current lead exposure and by redistribution of bone lead accumulated from past environmental exposures.     

Blood lead levels and death from all causes, cardiovascular disease, and cancer: results from the NHANES III mortality study

BACKGROUND: Analyses of mortality data for participants examined in 1976-1980 in the second National Health and Nutrition Examination Survey (NHANES II) suggested an increased risk of mortality at blood lead levels > 20 microg/dL. Blood lead levels have decreased markedly since the late 1970s. In NHANES III, conducted during 1988-1994, few adults had levels > 20 microg/dL. OBJECTIVE: Our objective in this study was to determine the risk of mortality in relation to lower blood lead levels observed for adult participants of NHANES III. METHODS: We analyzed mortality information for 9,757 participants who had a blood lead measurement and who were > or = 40 years of age at the baseline examination. Using blood lead levels categorized as < 5, 5 to < 10, and > or = 10 microg/dL, we determined the relative risk of mortality from all causes, cancer, and cardiovascular disease through Cox proportional hazard regression analysis. RESULTS: Using blood lead levels < 5 microg/dL as the referent, we determined that the relative risk of mortality from all causes was 1.24 [95% confidence interval (CI), 1.05-1.48] for those with blood levels of 5-9 microg/dL and 1.59 (95% CI, 1.28-1.98) for those with blood levels > or = 10 microg/dL (p for trend < 0.001). The magnitude of risk was similar for deaths due to cardiovascular disease and cancer, and tests for trend were statistically significant (p < 0.01) for both causes of death. CONCLUSION: In a nationally representative sample of the U.S. population, blood lead levels as low as 5-9 mug/dL were associated with an increased risk of death from all causes, cardiovascular disease, and cancer.     

Low-level environmental lead exposure and children's intellectual function: an international pooled analysis

Lead is a confirmed neurotoxin, but questions remain about lead-associated intellectual deficits at blood lead levels < 10 microg/dL and whether lower exposures are, for a given change in exposure, associated with greater deficits. The objective of this study was to examine the association of intelligence test scores and blood lead concentration, especially for children who had maximal measured blood lead levels < 10 microg/dL. We examined data collected from 1,333 children who participated in seven international population-based longitudinal cohort studies, followed from birth or infancy until 5-10 years of age. The full-scale IQ score was the primary outcome measure. The geometric mean blood lead concentration of the children peaked at 17.8 microg/dL and declined to 9.4 microg/dL by 5-7 years of age; 244 (18%) children had a maximal blood lead concentration < 10 microg/dL, and 103 (8%) had a maximal blood lead concentration < 7.5 microg/dL. After adjustment for covariates, we found an inverse relationship between blood lead concentration and IQ score. Using a log-linear model, we found a 6.9 IQ point decrement [95% confidence interval (CI), 4.2-9.4] associated with an increase in concurrent blood lead levels from 2.4 to 30 microg/dL. The estimated IQ point decrements associated with an increase in blood lead from 2.4 to 10 microg/dL, 10 to 20 microg/dL, and 20 to 30 microg/dL were 3.9 (95% CI, 2.4-5.3), 1.9 (95% CI, 1.2-2.6), and 1.1 (95% CI, 0.7-1.5), respectively. For a given increase in blood lead, the lead-associated intellectual decrement for children with a maximal blood lead level < 7.5 microg/dL was significantly greater than that observed for those with a maximal blood lead level > or = 7.5 microg/dL (p = 0.015). We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 microg/dL is associated with intellectual deficits.     

Gender differences in blood lead and hemoglobin levels in Andean adults with chronic lead exposure

A field study of the prevalence of lead (Pb) intoxication was conducted in 158 adults (67 men and 91 women) living at 2,500-2,800 meters in Ecuadorian Andean villages with high Pb contamination from local small-scale Pb-glazing cottage industries. Venous blood samples showed mean blood lead (PbB) levels of 34.5 microg/dL (SD 22.2) for men and 27.0 microg/dL (SD 18.4) for women; this difference was significant (t-test, p = 0.022; Mann-Whitney U, p = 0.044). An ANOVA showed no significant main effect for gender (F = 0.118, p = 0.782) or age (F = 2.479, p = 0.117), and no significant gender-by-age interaction (F = 0.273, p = 0.602). In the Pb-glazing study group, 39% of the men had PbB levels > or = 40 microg/dL, while 41% of the women had PbB levels > or = 30 microg/dL (the WHO health-based biological limits). A reference group of 39 adults (24 men and 15 women) had a mean PbB level of 5.9 microg/dL (SD 2.8; range: 1.8-16.8), significantly different from that of the 158 subjects in the study group (t-test, p < 0.0001). The difference in mean PbB levels of men (6.8 microg/dL) and women (4.7 microg/dL) in the reference group was significant (t-test, p = 0.026; Mann-Whitney U, p = 0.019). The mean altitude-corrected hemoglobin levels in the study group were lower than normal, 11.3 g/dL for men and 10.9 g/dL for women.     

Relationship of blood and bone lead to menopause and bone mineral density among middle-age women in Mexico City

To describe the relationship of blood lead levels to menopause and bone lead levels, we conducted a cross-sectional study on 232 pre- or perimenopausal (PreM) and postmenopausal (PosM) women who participated in an osteoporosis-screening program in Mexico City during the first quarter of 1995. Information regarding reproductive characteristics and known risk factors for blood lead was obtained using a standard questionnaire by direct interview. The mean age of the population was 54.7 years (SD = 9.8), with a mean blood lead level of 9.2 microg/dL (SD = 4.7/dL) and a range from 2.1 to 32.1 microg/dL. After adjusting for age and bone lead levels, the mean blood lead level was 1.98 microg/dL higher in PosM women than in PreM women (p = 0.024). The increase in mean blood lead levels peaked during the second year of amenorrhea with a level (10.35 microg/dL) that was 3.51 microg/dL higher than that of PreM women. Other important predictors of blood lead levels were use of lead-glazed ceramics, schooling, trabecular bone lead, body mass index, time of living in Mexico City, and use of hormone replacement therapy. Bone density was not associated with blood lead levels. These results support the hypothesis that release of bone lead stores increases during menopause and constitutes an internal source of exposure possibly associated with health effects in women in menopause transition.     

Blood lead level and risk of asthma

Asthma and lead poisoning are prevalent among urban children in the United States. Lead exposure may be associated with excessive production of immunoglobulin E, possibly increasing asthma risk and contributing to racial disparities. The objective of this study was to examine racial differences in the association of blood lead level (BLL) to risk of developing asthma. We established and followed a cohort prospectively to determine asthma onset, using patient encounters and drug claims obtained from hospital databases. Participants were managed care enrollees with BLL measured and documented at 1-3 years of age. We used multiple variable analysis techniques to determine the relationship of BLL to period prevalent and incident asthma. Of the 4,634 children screened for lead from 1995 through 1998, 69.5% were African American, 50.5% were male, and mean age was 1.2 years. Among African Americans, BLL > or = 5 and BLL > or = 10 microg/dL were not associated with asthma. The association of BLL > or = 5 microg/dL with asthma among Caucasians was slightly elevated, but not significant [adjusted hazard ratio (adjHR) = 1.4; 95% confidence interval (CI), 0.7-2.9; p = 0.40]. Despite the small number of Caucasians with high BLL, the adjHR increased to 2.7 (95% CI, 0.9-8.1; p = 0.09) when more stringent criteria for asthma were used. When compared with Caucasians with BLL < 5 microg/dL, African Americans were at a significantly increased risk of asthma regardless of BLL (adjHR = 1.4-3.0). We conclude that an effect of BLL on risk of asthma for African Americans was not observed. These results demonstrate the need for further exploration of the complex interrelationships between race, asthma phenotype, genetic susceptibilities, and socioenvironmental exposures, including lead.     

Early Pregnancy Blood Lead and Spontaneous Abortion

Although evidence tends to suggest that high levels of lead exposure increase the risk of spontaneous abortion, we do not yet know whether moderate- to low-level exposure elevates risk. Among 351 women (aged 16 to 35 years, with single pregnancies) who were registered for a longitudinal study, 15 (4.3%) women experienced spontaneous abortion after the 12th week of gestation and before the 20th week. We collected participants' blood samples during the first trimester of pregnancy (8–12 weeks) for lead measurement by inductively coupled plasma-mass spectrometry. Mean ± standard deviation of blood lead was 3.8 ± 2.0 μg/dl (range 1.0–20.5 μg/dl) with a geometric mean of 3.5 μg/dl. Mean blood lead concentrations did not differ significantly between spontaneous abortion cases and ongoing pregnancies (3.51 ± 1.42 and 3.83 ± 1.99 μg/dl, respectively). The findings suggest that in apparently healthy women, low blood lead levels (mean <5 μg/dl) measured in early pregnancy may not be a risk factor for spontaneous abortion.     

Blood lead levels among children of lead-exposed workers: A meta-analysis.

BACKGROUND: To further assess the utility of targeted blood lead screening for children from households with members having occupational lead exposures, we conducted a meta-analysis of all available reports of take-home lead exposures. Our objective was to estimate the blood lead levels among U.S. children (ages 1-5) from households with lead-exposed workers. METHODS: Reports considered for inclusion were cited in Medline, Toxline, Excerpta Medica, and Bio-Med plus all unpublished reports available at the National Institute for Occupational Safety and Health through 1994. The a priori criteria for inclusion of U.S. reports required their having data on: (1) venous blood lead levels for children, (2) children's ages, (3) data for at least five children, (4) workers' occupations, (5) workers' blood lead levels, and (6) data collection methods. RESULTS: Based on a meta-analysis of 10 reports from 1987 through 1994, the children (n=139) of lead-exposed workers (n=222) had a geometric mean blood lead level of 9.3 microg/dL compared to a U.S. population geometric mean of 3.6 microg/dL (P=0.0006). Also in this group, 52% of the children had blood lead levels (BLLs) >/= 10 microg/dL compared to 8.9% in the U.S. (P=.0010), and 21% of the children had BLLs >/= 20 microg/dL compared to 1.1% in the U.S. (P=. 0258). CONCLUSIONS: We estimate, based on 1981-83 survey data, that there are about 48,000 families with children under six living with household members occupationally exposed to lead. If the findings from this meta-analysis (admittedly limited by small numbers) are generalizable, about half of the young children in these families may have BLLs >/= 10 microg/dL. Data were too sparse to determine if children of workers with elevated blood leads were at greater risk than children whose parents were only known to be lead exposed. Our findings support the position that children of lead-exposed workers should be targeted for blood lead screening. Am. J. Ind. Med. 36:475-481, 1999. Published 1999 Wiley-Liss, Inc.     

Low blood lead concentration in association with infertility in women

This study investigated the relationship between low-level lead exposure and risk of infertility in women. Study participants consisted of 64 cases recruited at a private infertility clinic and 83 control women from the postpartum clinic unit at a medical center in Kaohsiung, Taiwan. With informed consent, venous blood samples were obtained from subjects, during their early follicular phases (the 1st to 5th days of the menstrual cycle), for measuring concentrations of lead and hormones. Information on other potential risk factors associated with infertility, including reproductive history, Chinese herbal Medicine use, dairy product consumption, residential environment, and sociodemographic status, was obtained during an in-person interview. The mean blood lead level (BLL) in infertile women was significantly higher than that in controls (3.55 vs 2.78 microg/dL, P=0.007). Compared to women with BLL < or = 2.5 microg/dL, women with BLL>2.5 microg/dL were associated with a threefold increased risk for infertility (adjusted odds ratio=2.94, 95% confidence interval 1.18-7.34), after controlling for age, body mass index, smoking, Chinese herbal Medicine use, and irregular menstruation. Women's BLL was a significant predictor of the serum estradiol concentration also. These findings suggest an important role of very low BLL in the risk of infertility in women.     

Blood lead concentrations < 10 microg/dL and child intelligence at 6 years of age

BACKGROUND: Few studies provide data directly relevant to the question of whether blood lead concentrations < 10 microg/dL adversely affect children's cognitive function. OBJECTIVE: We examined the association between blood lead concentrations assessed throughout early childhood and children's IQ at 6 years of age. METHODS: Children were followed from 6 months to 6 years of age, with determination of blood lead concentrations at 6, 12, 18, and 24 months, and 3, 4, 5, and 6 years of age. At 6 years of age, intelligence was assessed in 194 children using the Wechsler Preschool and Primary Scale of Intelligence-Revised. We used general linear and semiparametic models to estimate and test the association between blood lead concentration and IQ. RESULTS: After adjustment for maternal IQ, HOME scale scores, and other potential confounding factors, lifetime average blood lead concentration (mean = 7.2 microg/dL; median = 6.2 microg/dL) was inversely associated with Full-Scale IQ (p = 0.006) and Performance IQ scores (p = 0.002). Compared with children who had lifetime average blood lead concentrations < 5 microg/dL, children with lifetime average concentrations between 5 and 9.9 microg/dL scored 4.9 points lower on Full-Scale IQ (91.3 vs. 86.4, p = 0.03). Nonlinear modeling of the peak blood lead concentration revealed an inverse association (p = 0.003) between peak blood lead levels and Full-Scale IQ down to 2.1 microg/dL, the lowest observed peak blood lead concentration in our study. CONCLUSIONS: Evidence from this cohort indicates that children's intellectual functioning at 6 years of age is impaired by blood lead concentrations well below 10 microg/dL, the Centers for Disease Control and Prevention definition of an elevated blood lead level.     

Blood lead in children and its determinants in Nagpur, India

In a community-based cross-sectional study of 297 children aged 6 months to 6 years in an Indian city, the authors assessed the prevalence of elevated (> or = 10 microg/dL) blood lead (PbB) levels, their risk factors, and the lead contents in potential environmental sources. Mean PbB was 18.4 microg/dL +/- 16.5. The prevalence of elevated PbB was 67%. Anticipated risk factors for elevated PbB were living in houses painted with lead-based paint, odds ratio (OR) 6.42 (1.75, 23.6; p = 0.005), recent exposures to lead-based paint, OR 2.61 (1.07, 6.66; p = 0.03), and the use of the eye cosmetic ma," OR 2.63 (1.24, 5.56; p = 0.01). Unanticipated results were effect of upper caste as a risk factor, OR (adjusted) 1.85 (95% CI = 0.96, 3.57; p = 0.06), and the lack of effect of traffic, parental occupational exposure, or nutritional status. Analysis of various environmental sources such as paint, pencils, crayons, and clay revealed high lead levels. These results demonstrate the existence of a major environmental health problem in Indian children, with risk factors that differ from those in other countries.     

Moderate alcohol intake in pregnancy and the risk of spontaneous abortion

Women attending routine antenatal care at Aarhus University Hospital, Denmark, from 1989 to 1996 were eligible for this cohort study on the association between alcohol intake in pregnancy and the risk of spontaneous abortion. We included 24 679 singleton pregnancies in the study. We used Cox regression analyses with delayed entry for the analyses. We found an increased risk of spontaneous abortion in the first trimester (7-11 completed weeks of gestation) for women consuming > or =5 drinks/week. We found no association between alcohol intake and spontaneous abortion during the second trimester. Common methodological problems in relation to studies on spontaneous abortions are discussed, as are problems with possible under-reporting of alcohol consumption. We conclude that women consuming > or =5 drinks/week are at increased risk of first trimester spontaneous abortion.     

Predictors of blood lead levels in agricultural villages practicing wastewater irrigation in Central Mexico

To investigate whether the agricultural use of untreated wastewater (i.e. crop irrigation) was associated with elevated blood lead levels in a farming population in the Mezquital Valley and which risk factors, other than exposure to untreated wastewater, were associated with elevated blood lead levels, lead levels were measured in venous blood obtained from 735 individuals. Blood samples were analyzed by atomic absorption spectrophotometry. Food habits and dietary intake were gathered by interview, using a semi-quantitative food-frequency questionnaire. The average blood lead level was 7.8 microg/dL (SD 4.66 microg/dL; range 1.2-36.7 microg/dL). 23% of the study population had blood lead levels exceeding 10 microg/dL. The use of lead-glazed ceramics (LGC) was significantly associated with elevated lead levels (p = < 0.001). Other significant variables included age, gender (males), and non-farming-related occupations (e.g., technicians, factory workers). p = 0.005, 0.08, and 0.001, respectively. When the analysis was stratified by the use of LGC for food preparation, an inverse relationship between higher daily calcium intake and blood lead level was detected (beta = - 0.040, p = < 0.05). Thus, blood lead levels were positively associated with the use of LGC. Calcium intake showed a protective effect, maybe by decreasing absorption of lead in the gastrointestinal tract. No association between occupational exposure to untreated wastewater or crop consumption and blood lead levels was detected. Further environmental and health surveillance is recommended.     

Recommendations for medical management of adult lead exposure

Research conducted in recent years has increased public health concern about the toxicity of lead at low dose and has supported a reappraisal of the levels of lead exposure that may be safely tolerated in the workplace. In this article, which appears as part of a mini-monograph on adult lead exposure, we summarize a body of published literature that establishes the potential for hypertension, effects on renal function, cognitive dysfunction, and adverse female reproductive outcome in adults with whole-blood lead concentrations < 40 microg/dL. Based on this literature, and our collective experience in evaluating lead-exposed adults, we recommend that individuals be removed from occupational lead exposure if a single blood lead concentration exceeds 30 microg/dL or if two successive blood lead concentrations measured over a 4-week interval are > or = 20 microg/dL. Removal of individuals from lead exposure should be considered to avoid long-term risk to health if exposure control measures over an extended period do not decrease blood lead concentrations to < 10 microg/dL or if selected medical conditions exist that would increase the risk of continued exposure. Recommended medical surveillance for all lead-exposed workers should include quarterly blood lead measurements for individuals with blood lead concentrations between 10 and 19 microg/dL, and semiannual blood lead measurements when sustained blood lead concentrations are < 10 microg/dL. It is advisable for pregnant women to avoid occupational or avocational lead exposure that would result in blood lead concentrations > 5 microg/dL. Chelation may have an adjunctive role in the medical management of highly exposed adults with symptomatic lead intoxication but is not recommended for asymptomatic individuals with low blood lead concentrations.     

Demographic and socioeconomic factors associated with blood lead levels among Mexican-American children and adolescents in the United States

OBJECTIVE: This study was designed to assess demographic and socioeconomic differences in blood lead levels (BLLs) among Mexican-American children and adolescents in the United States. METHODS: We analyzed data from the Third National Health and Nutrition Examination Survey, 1988-1994, for 3,325 Mexican-American youth aged 1 to 17 years. The main study outcome measures included a continuous measure (microg/dL) of BLL and two dichotomous measures of BLL (> or =5 microg/dL and > or =10 microg/dL). RESULTS: The mean BLL among Mexican-American children in the United States was 3.45 microg/dL (95% confidence interval [CI] 3.07, 3.87); 20% had BLL > or =5 microg/dL (95% CI 15%, 24%); and 4% had BLL > or =10 microg/dL (95% CI 2%, 6%). In multivariate analyses, gender, age, generational status, home language, family income, education of head of household, age of housing, and source of drinking water were statistically significant independent predictors (p<0.05) of having higher BLLs and of having BLL > or =5 microg/dL, whereas age, family income, housing age, and source of drinking water were significant predictors (p<0.05) of having BLL > or =10 microg/dL. CONCLUSIONS: Significant differences in the risk of having elevated BLLs exist among Mexican-American youth. Those at greatest risk should be prioritized for lead screening and lead exposure abatement interventions.     

Succimer (meso-2,3-dimercaptosuccinic acid (DMSA)) treatment of Andean children with environmental lead exposure

The authors studied children in Andean villages contaminated by a lead-glazing cottage industry. Mean blood lead (PbB) level in 35 exposed children, aged 3-14 years, a year before treatment, at the time of initiation of a comprehensive lead education and prevention program, was 53.4 microg/dL. PbB levels immediately before and three weeks after a ten-day regimen of succimer treatment of the 35 children were 43.4 microg/dL and 34.3 microg/dL, respectively, showing a 21% reduction and a significant difference between means (t = 5.09, p = 0.0001). PbB levels of the same children a year before treatment and immediately pre-treatment were also significantly different (t = 10.59, p = 0.0001). Thus, a ten-day course of succimer chelation effectively reduced PbB in children with moderate to severe Pb intoxication, and the education and prevention program, initiated with parents, health care providers, and educators, also contributed significantly to reducing PbB.     

Lead exposure among females of childbearing age--United States, 2004

For centuries, exposure to high concentrations of lead has been known to pose health hazards, and evidence is mounting regarding adverse health effects from moderate- and low-level blood lead concentrations. Public health authorities use higher levels to define blood lead levels (BLLs) of concern in nonpregnant females (> or =25 microg/dL) compared with children (> or =10 microg/dL) and a lower level (> or =5 microg/dL) for pregnant females. This difference in levels for nonpregnant and pregnant females has raised concern because of the recognition that a proportion of nonpregnant females with BLLs > or =5 microg/dL will become pregnant and potentially expose their infants to a risk for adverse health effects from lead. Maternal and fetal BLLs are nearly identical because lead crosses the placenta unencumbered. This report summarizes 2004 surveillance data regarding elevated BLLs among females of childbearing age (i.e., aged 16-44 years) in 37 states participating in CDC's Adult Blood Lead Epidemiology and Surveillance (ABLES) program. The results indicated that rates of elevated BLLs ranged from 0.06 per 100,000 females of childbearing age at BLLs of > or =40 microg/dL to 10.9 per 100,000 females at BLLs of > or =5 microg/dL. Primary and secondary prevention of lead exposure among females of childbearing age is needed to avert neurobehavioral and cognitive deficits in their offspring.