Should the Centers for Disease Control and Prevention's childhood lead poisoning intervention level be lowered?

A Prospective Birth Cohort Study on Early Childhood Lead Levels and Attention Deficit Hyperactivity Disorder: New Insight on Sex Differences

OBJECTIVE

To investigate the prospective associations between early childhood lead exposure and subsequent risk of attention deficit hyperactivity disorder (ADHD) in childhood and its potential effect modifiers.

STUDY DESIGN

We analyzed data from 1479 mother-infant pairs (299 ADHD, 1180 neurotypical) in the Boston Birth Cohort. The child's first blood lead measurement and physician-diagnosed ADHD was obtained from electronic medical records. Graphic plots and multiple logistic regression were used to examine dose-response associations between lead exposure and ADHD and potential effect modifiers, adjusting for pertinent covariables.

RESULTS

We found that 8.9% of the children in the Boston Birth Cohort had elevated lead levels (5-10 µg/dL) in early childhood, which was associated with a 66% increased risk of ADHD (OR, 1.66; 95% CI, 1.08-2.56). Among boys, the association was significantly stronger (OR, 2.49; 95% CI, 1.46-4.26); in girls, the association was largely attenuated (P value for sex-lead interaction = .017). The OR of ADHD associated with elevated lead levels among boys was reduced by one-half if mothers had adequate high-density lipoprotein levels compared with low high-density lipoprotein, or if mothers had low stress compared with high stress during pregnancy.

CONCLUSIONS

Elevated early childhood blood lead levels increased the risk of ADHD. Boys were more vulnerable than girls at a given lead level. This risk of ADHD in boys was reduced by one-half if the mother had adequate high-density lipoprotein levels or low stress. These findings shed new light on the sex difference in ADHD and point to opportunities for early risk assessment and primary prevention of ADHD.

Costs of IQ Loss from Leaded Aviation Gasoline Emissions

In the United States, general aviation piston-driven aircraft are now the largest source of lead emitted to the atmosphere. Elevated lead concentrations impair children's IQ and can lead to lower earnings potentials. This study is the first assessment of the nationwide annual costs of IQ losses from aircraft lead emissions. We develop a general aviation emissions inventory for the continental United States and model its impact on atmospheric concentrations using the community multi-scale air quality model (CMAQ). We use these concentrations to quantify the impacts of annual aviation lead emissions on the U.S. population using two methods: through static estimates of cohort-wide IQ deficits and through dynamic economy-wide effects using a computational general equilibrium model. We also examine the sensitivity of these damage estimates to different background lead concentrations, showing the impact of lead controls and regulations on marginal costs. We find that aircraft-attributable lead contributes to $1.06 billion 2006 USD ($0.01-$11.6) in annual damages from lifetime earnings reductions, and that dynamic economy-wide methods result in damage estimates that are 54% larger. Because the marginal costs of lead are dependent on background concentration, the costs of piston-driven aircraft lead emissions are expected to increase over time as regulations on other emissions sources are tightened.

Neurotoxicants, Micronutrients, and Social Environments

SUMMARY—Systematic research evaluating the separate and interacting impacts of neurotoxicants, micronutrients, and social environments on children's cognition and behavior has only recently been initiated. Years of extensive human epidemiologic and animal experimental research document the deleterious impact of lead and other metals on the nervous system. However, discrepancies among human studies and between animal and human studies underscore the importance of variations in child nutrition as well as social and behavioral aspects of children's environments that mitigate or exacerbate the effects of neurotoxicants.

In this monograph, we review existing research on the impact of neurotoxic metals, nutrients, and social environments and interactions across the three domains. We examine the literature on lead, mercury, manganese, and cadmium in terms of dispersal, epidemiology, experimental animal studies, effects of social environments, and effects of nutrition.

Research documenting the negative impact of lead on cognition and behavior influenced reductions by the Center for Disease Control in child lead-screening guidelines from 30 micrograms per deciliter (μg/dL) in 1975 to 25 μg/dL in 1985 and to 10 μg/dL in 1991. A further reduction is currently being considered. Experimental animal research documents lead's alteration of glutamate-neurotransmitter (particularly N-methyl-D-aspartate) activity vital to learning and memory. In addition, lead induces changes in cholinergic and dopaminergic activity. Elevated lead concentrations in the blood are more common among children living in poverty and there is some evidence that socioeconomic status influences associations between lead and child outcomes. Micronutrients that influence the effects of lead include iron and zinc.

Research documenting the negative impact of mercury on children (as well as adults) has resulted in a reference dose (RfD) of 0.1 microgram per kilogram of body weight per day (μg/kg/day). In animal studies, mercury interferes with glutamatergic, cholinergic, and dopaminergic activity. Although evidence for interactions of mercury with children's social contexts is minimal, researchers are examining interactions of mercury with several nutrients.

Research on the effects of cadmium and manganese on child cognition and behavior is just beginning. Experimental animal research links cadmium to learning deficits, manganese to behaviors characteristic of Parkinson's disease, and both to altered dopaminergic functioning.

We close our review with a discussion of policy implications, and we recommend interdisciplinary research that will enable us to bridge gaps within and across domains.

Blood lead levels in schoolchildren living near an industrial zone in Cali, Colombia: the role of socioeconomic condition

This study aimed to determine Blood Lead Levels (BLL) in schoolchildren 6-14 years old exposed to industrial sources of lead and evaluated the role of socioeconomic condition. A cross-sectional study was conducted in an area likely to be exposed to industrial pollutants in northern Cali (i.e., distance and wind direction) and in a "non-exposed" area. In children in two schools of corresponding study areas, venous samples (5 ml) were collected to determine BLL by graphite furnace absorption spectrometry. Using regression models, we evaluated the association between risk factors to BLL and the effect of modification with variables of socioeconomic condition. We enrolled 350 schoolchildren. Schoolchildren in the exposed area had higher prevalence of BLL of ≥ 5 μg/dl (44.2 vs. 8.2 %, p = 0.000) than those in non-exposed area. A positive association was found between exposure and BLL of ≥ 5 μg/dl (prevalence ratios (PR), 6.68; 95 % confidence interval (95 % CI), 3.95, 11.29). Demographic characteristics and socioeconomic condition such as age (PR, 1.45; 95 % CI, 1.03, 2.04), sex (PR, 1.84; 95 % CI, 1.30, 2.60), race (PR, 2.32; 95 % CI, 1.39, 3.89) and socioeconomic position (SEP; PR, 2.02; 95 % CI, 1.35, 3.04) were statistically significant and independently associated with BLL. There was a synergistic interaction between exposure to the industrial zone and SEP for higher BLL (coefficient, 0.80; 95 % CI, 0.17, 1.43). Residence in the northern urban area of Cali exposed to pollutants of an industrial zone is associated to an increased risk of higher BLL, especially among children from low SEC who are at greater risk of exposure and susceptibility.

Avaliação audiológica em crianças com baixo nível de exposição cumulativa ao chumbo

Objetivo verificar a ocorrência de perda auditiva sensorioneural em crianças com baixo nível de exposição cumulativa ao chumbo. Métodos 156 crianças intoxicadas por chumbo, 94 do sexo masculino e 62 do sexo feminino, na faixa etária entre 18 meses a 14 anos e 5 meses, foram submetidas a análise longitudinal do nível de Plumbemia em sangue, bem como audiometria tonal liminar e emissões otoacústicas evocadas por estímulo transiente. Resultados a população pesquisada apresentou um valor médio de Plumbemia estimada de 12,2±5,7mg/dL (faixa entre 2,4-33mg/dL); todas as crianças apresentaram resposta normal na audiometria tonal liminar em 20 dBNA nas frequências testadas, 0,5; 1; 2 e 4 kHz, para ambas as orelhas; as emissões otoacústicas evocadas por estímulo transiente estiveram presentes para todas as frequências bilateralmente, nas 79 crianças pesquisadas. Conclusão não foi constatada perda auditiva sensorioneural em crianças com histórico de baixo nível de exposição cumulativa por chumbo, assim como não foi encontrada lesão de células ciliadas externas na cóclea, mesmo que subclínicas.

Environmental lead poisoning among children in Porto Alegre state, Southern Brazil

OBJECTIVE

To estimate the prevalence of lead poisoning in children and to identify associated factors, as well as possible local sources of contamination.

METHODS

A cross-sectional prevalence study conducted in 2006 with a random sample of 97 children age zero to five years from a neighborhood in Porto Alegre, Southern Brazil. Blood lead levels were measured and a questionnaire administered to collect information on sociodemographics, recycling and dwelling. A preliminary environmental evaluation was carried out with direct analysis of soil and indirect analysis of air pollution with bioindicators to identify possible sources of contamination. To analyze lead concentrations from the different collection sites, for each type of material studied, ANOVA was performed with a Brown-Forsythe adjustment for heteroscedasticity and with Dunnett's T3 procedure for multiple comparisons of unequal variances.

RESULTS

Blood lead levels > 10.0 µg/dL was found in 16.5% of children. Recycling of waste at home, low father's education level, and increased age of children were associated with increase blood lead levels. High lead levels were found in soil, and there was little indication of lead air pollution.

CONCLUSIONS

A high prevalence of lead poisoning was identified, and the potential sources of contamination in this community appear related to waste recylcing activities. Studies should be conducted with other populations of Brazilian children and evaluate potential sources of local and general contamination, to accurately characterize this issue in Brazil.

Community blood lead survey with emphasis on preschool children following lead dust pollution in Esperance, Western Australia

OBJECTIVE

To assess the impact of airborne lead dust on blood lead levels in residents of Esperance, a regional Western Australian town, with particular reference to preschool children.

METHODS

Following identification of significant airborne lead contamination, residents were notified that a blood lead clinic was available to all, with testing of preschool children encouraged. About 40% (333 children) of the preschool group and about 20% of the remaining population were tested. The main measures were blood lead levels, prevalence of elevated results and comparisons to other Western Australian surveys.

RESULTS

In preschoolers, 2.1% (seven children) had blood lead levels exceeding the current 10 μg/dL level of concern. This was not significantly different to two previous community-based surveys elsewhere in Western Australia. However, at a lower cut-off of 5 μg/dL, the prevalence of elevated lead levels was 24.6%, significantly higher than children tested in a previous Western Australian survey. The prevalence of blood lead levels of 10 μg/dL or greater in adults was 1.3% (26 adults), not significantly different from a previous Western Australian survey.

CONCLUSIONS

The prevalence of preschool children with blood lead levels exceeding the current level of concern was not significantly increased. However, the increased prevalence of children with lead levels at or above 5 μg/dL demonstrates exposure to lead dust pollution.

IMPLICATIONS

This episode of lead dust contamination highlights the need for strict adherence to environmental controls and effective monitoring processes to ensure the prevention of future events.

Low-level lead exposure and elevations in blood pressure during pregnancy

BACKGROUND

Lead exposure is associated with elevated blood pressure during pregnancy; however, the magnitude of this relationship at low exposure levels is unclear.

OBJECTIVES

Our goal was to determine the association between low-level lead exposure and blood pressure during late pregnancy.

METHODS

We collected admission and maximum (based on systolic) blood pressures during labor and delivery among 285 women in Baltimore, Maryland. We measured umbilical cord blood lead using inductively coupled plasma mass spectrometry. Multivariable models were adjusted for age, race, median household income, parity, smoking during pregnancy, prepregnancy body mass index, and anemia. These models were used to calculate benchmark dose values.

RESULTS

Geometric mean cord blood lead was 0.66 μg/dL (95% confidence interval, 0.61-0.70). Comparing blood pressure measurements between those in the highest and those in the lowest quartile of lead exposure, we observed a 6.87-mmHg (1.51-12.21 mmHg) increase in admission systolic blood pressure and a 4.40-mmHg (0.21-8.59 mmHg) increase in admission diastolic blood pressure after adjustment for confounders. Corresponding values for maximum blood pressure increase were 7.72 (1.83-13.60) and 8.33 (1.14-15.53) mmHg. Benchmark dose lower limit values for a 1-SD increase in blood pressure were < 2 μg/dL blood lead for all blood pressure end points.

CONCLUSIONS

A significant association between low-level lead exposures and elevations in maternal blood pressure during labor and delivery can be observed at umbilical blood lead levels < 2 μg/dL.

Potential for childhood lead poisoning in the inner cities of Australia due to exposure to lead in soil dust

This article presents evidence demonstrating that the historical use of leaded gasoline and lead (Pb) in exterior paints in Australia has contaminated urban soils in the older inner suburbs of large cities such as Sydney and Melbourne. While significant attention has been focused on Pb poisoning in mining and smelting towns in Australia, relatively little research has focused on exposure to Pb originating from inner-city soil dust and its potential for childhood Pb exposures. Due to a lack of systematic blood lead (PbB) screening and geochemical soil Pb mapping in the inner cities of Australia, the risks from environmental Pb exposure remain unconstrained within urban population centres.

Prenatal and adolescent blood lead levels in South Africa: child, maternal and household risk factors in the Birth to Twenty cohort

INTRODUCTION

The risk factors for lead exposure in developing countries have not been fully described. This study looks at child, maternal and household factors associated with increased risk of lead exposure at birth and at 13 years of age in the Birth to Twenty cohort.

METHODS

Mothers were recruited from antenatal clinics in the Johannesburg-Soweto metropolitan area in 1990 (n=3273). Lead levels were analysed in cord blood collected at birth (n=618) and at 13 years (n=1546). Data on selected child, maternal and household factors were collected using a structured questionnaire in the third trimester and at 13 years of age. Statistical analyses were conducted to determine the associated risk factors.

RESULTS

The mean blood lead level at birth was 5.85 microg/dl, and at 13 years of age it was 5.66 microg/dl. The majority of children had blood lead levels above 5 microg/dl (52% at birth and 56% at 13 years). At birth, being a teenage mother and having low educational status were strong predictors for elevated cord blood lead levels. Being a male child, having an elevated cord blood level, and lack of household ownership of a phone were significant risk factors for high blood lead levels at 13 years.

CONCLUSION

Significant associations found in the study point to the low socio-economic status of lead-affected mothers and children. These poor circumstances frequently persist into later childhood, resulting in continued high lead levels. Thus broader measures of poverty alleviation and provision of better education may help decrease the risk of exposure.

A blood lead benchmark for assessing risks from childhood lead exposure

Lead exposure is an insidious problem, causing subtle effects in children at low exposure levels where clinical signs are not apparent. Although a target blood lead concentration (Pb(B)) of ten micrograms per deciliter (10 microg/dL) has been used as the basis for environmental decision-making in California for nearly two decades, recent epidemiologic evidence suggests a relationship between cognitive deficits and Pb(B) at concentrations < 10 microg/dL. Based on a published meta-analysis of children's IQ scores and their blood lead concentrations, we developed a new blood lead benchmark: an incremental increase in blood lead concentration (DeltaPb(B)) of 1 microg/dL, an increase that we estimate could decrease the IQ score in an average school child in California by up to one point. Although there is no evidence to date for a threshold for the neurobehavioral effects of lead, a one-point IQ decrement was chosen to represent a de minimus change. To safeguard the intellectual potential of all children, additional efforts to reduce or eliminate multiple-source exposures to lead are warranted.

Childhood lead poisoning: conservative estimates of the social and economic benefits of lead hazard control

BACKGROUND

This study is a cost-benefit analysis that quantifies the social and economic benefits to household lead paint hazard control compared with the investments needed to minimize exposure to these hazards.

OBJECTIVES

This research updates estimates of elevated blood lead levels among a cohort of children < or = 6 years of age and compiles recent research to determine a range of the costs of lead paint hazard control ($1-$11 billion) and the benefits of reduction attributed to each cohort for health care ($11-$53 billion), lifetime earnings ($165-$233 billion), tax revenue ($25-$35 billion), special education ($30-$146 million), attention deficit-hyperactivity disorder ($267 million), and the direct costs of crime ($1.7 billion).

RESULTS

Each dollar invested in lead paint hazard control results in a return of $17-$221 or a net savings of $181-269 billion.

CONCLUSIONS

There are substantial returns to investing in lead hazard control, particularly targeted at early intervention in communities most likely at risk. Given the high societal costs of inaction, lead hazard control appears to be well worth the price.

Emerging aspects of assessing lead poisoning in childhood

This review covers the epidemiology of lead poisoning in children on a global scale. Newer sources of lead poisoning are identified. The methods that are used to assess a population of children exposed to lead are discussed, together with the ways of undertaking an exposure risk assessment; this includes assessing the time course and identifying sources of lead exposure. Human assessment measures for lead toxicity, such as blood lead concentrations, deciduous tooth lead, and use of zinc protoporphyrin estimations are evaluated. The role of isotopic fingerprinting techniques for identifying environmental sources of exposure is discussed. Among emerging data on the cognitive and behavioral effects of lead on children, the review considers the growing evidence of neurocognitive dysfunction with blood lead concentrations even below 10 µg/dl. The challenge of assessing and explaining the risk that applies to an individual as opposed to a population is discussed. Intervention strategies to mitigate risk from lead are examined together with the limited role for and limitations of chelation therapy for lead. Lessons learned from managing a population lead-dust exposure event in Esperance, Western Australia in 2007 are discussed throughout the review.

The lead industry and lead water pipes "A Modest Campaign"

Lead pipes for carrying drinking water were well recognized as a cause of lead poisoning by the late 1800s in the United States. By the 1920s, many cities and towns were prohibiting or restricting their use. To combat this trend, the lead industry carried out a prolonged and effective campaign to promote the use of lead pipes. Led by the Lead Industries Association (LIA), representatives were sent to speak with plumbers' organizations, local water authorities, architects, and federal officials. The LIA also published numerous articles and books that extolled the advantages of lead over other materials and gave practical advice on the installation and repair of lead pipes. The LIA's activities over several decades therefore contributed to the present-day public health and economic cost of lead water pipes.

Estimated burden of blood lead levels 5 microg/dl in 1999-2002 and declines from 1988 to 1994

In light of recent data suggesting adverse health effects at blood lead levels (PbB) <10 microg/dl, lowering the current definition of elevated blood lead (>or=10 microg/dl) has been recommended. To ascertain the population level impact of such a change, we calculated the prevalence of PbB >or=5 microg/dl in 1-21-year-old population in the United States. Furthermore, we characterized changes in PbB between 1988-1994 and 1999-2002. We analyzed data from the National Health and Nutrition Examination Survey (NHANES) III (n=10,755) and NHANES 1999-2002 (n=8013). In 1999-2002, about 91.7% of study children had detectable levels of lead in the blood. Among them, 7.3%, 2.8%, and 1.0% children and adolescents aged 1-5, 6-11, and 12-21 years, respectively, had PbB between 5 and 9.9 microg/dl. This number translates to approximately 2.4 million individuals. Between 1988-1994 and 1999-2002, the geometric mean PbB declined from 2.88 to 1.94 microg/dl in children 1-5 years, 1.80 to 1.36 microg/dl in children 6-11 years, and 1.24-1.02 microg/dl in children and adolescents 12-21 years of age. Also, the prevalence of PbB >or=5 microg/dl declined from 25.7% to 8.8%, 12.8% to 3.0%, and 7.5% to 1.2% in these age groups, respectively.A substantial proportion of children may be at risk for adverse health effects from lead exposure below 10 microg/dl and a large number of children will be classified as having elevated PbB if 5 microg/dl is considered the threshold. Significant public health resources will have to be mobilized for intervention, screening, and case management of these children.

A rationale for lowering the blood lead action level from 10 to 2 microg/dL

Fifteen years ago, in 1991, the U.S. Centers for Disease Control and Prevention (CDC) established 10 microg/dL as the lowest level of concern for children's blood lead levels. This value is extremely important because, historically, policy makers and public health officials generally have acted to remove sources of lead exposure only after the CDC's level of concern had been exceeded. A growing body of evidence, however, reveals that blood lead levels below 10 microg/dL may impair neurobehavioral development. There is now sufficient and compelling scientific evidence for the CDC to lower the blood lead action level in children. This review argues that a level of 2 microg/dL is a useful and feasible replacement. Although it can be argued, in turn, that no threshold for the health effects of lead is demonstrable, analytically a blood level of 2 microg/dL is readily and accurately measured and provides a benchmark for successful prevention. Lowering the level of concern would encourage and accelerate the investments needed to ensure that children are protected from lead exposure in their homes, schools, and play settings. Such a program would also offer economic advantages because of the coupling between lead, educational attainment, earnings and anti-social conduct. By lowering the blood action level, CDC will promote policies and initiatives designed to further reduce children's exposure to this potent developmental neurotoxicant.

Lead and copper in drinking water fountains--information for physicians

BACKGROUND

Lead and copper are potentially toxic metals. The objective of our work was to test the water from the drinking fountains of a large public access office complex in southwest Houston, Texas, for the presence of lead, copper, and microbiologic contamination. The data for the water fountains were compared with what we found in the local municipal drinking water supplies.

METHODS

Samples were collected as the first draw at the beginning of the work week. These samples were acidified to prevent the precipitation of heavy metals and analyzed using United States Environmental Protection Agency (USEPA) approved procedures and quality control.

RESULTS

Traces of lead were detected in 37.5% and copper in 100% of the tested water fountains. In two buildings, concentrations in some fountains exceeded the USEPA action level for lead (by up to 12-fold) and for copper (by up to 3.9 fold). One sample was positive for total coliform and Escherichia coli bacteria. Comparison with samples from the local municipal drinking water supplies indicated that both metals and bacteria were the result of secondary contamination at the water fountain sites.

CONCLUSIONS

This study showed that drinking water fountains can be an unexpected and unappreciated source of intake of metal and bacterial contaminants.

Deficits in cognitive function and achievement in Mexican first-graders with low blood lead concentrations

Elevated blood lead levels in children are associated with lower scores on tests of cognitive functioning. Recent studies have reported inverse relations between lifetime exposure and intellectual functioning at blood lead concentrations below 10 microg/dL, the Centers for Disease Control and Prevention's (CDC) level of concern. We report associations between blood lead and cognitive performance for first-grade Mexican children living near a metal foundry. Using a cross-sectional design, we examined the relation between children's concurrent blood lead concentrations (mean (SD) 11.4 microg/dL (6.1)) and their performance on 14 tests of global or specific cognitive functions. The blood lead-cognition relations were modeled using both linear and nonlinear methods. After adjustment for covariates, a higher blood lead level was associated with poorer cognitive performance on several cognitive tests. Segmented linear regressions revealed significant effects of lead but only for the segments defined by a concurrent blood lead concentration below 10-14 microg/dL. One implication of these findings is that at the age of 7 years, even in the absence of information on lead exposure in infancy and early childhood, a test result with blood lead < 10 microg/dL should not be considered safe. Together with other recent findings, these results add to the empirical base of support available for evaluating the adequacy of current screening guidelines and for motivating efforts at primary prevention of childhood lead exposure.

Comparison of parental report of blood lead testing in children enrolled in Medicaid with Medicaid claims data and blood lead surveillance reports

The purposes of this study were to identify the congruence of blood lead testing based on parental self-reports with Medicaid claims and blood lead surveillance records, and to determine factors associated with agreement between parental reports of blood lead tests and Medicaid claims or blood lead surveillance records. Data were obtained from a cross-sectional mailed survey of a randomly selected sample of parents of children 1-2 years old enrolled in Medicaid (n=532) and from existing Medicaid claims and blood lead surveillance records. Fifty-six percent of survey respondents reported their child had a blood lead test completed. Of these, only 56% could be confirmed with Medicaid claims/blood lead surveillance data. Logistic regression analysis revealed the odds of blood lead testing per parental report confirmed with Medicaid claims/blood lead surveillance data were 2.6 times greater if the child had > or =3 provider visits, 2.5 times greater if parents reported receiving a reminder about blood lead testing, 2.2 times greater if parents reported receiving information about lead poisoning, 1.6 times greater if residing in an urban county, and 1.5 times greater if the child was more than 2 years old. In conclusion, parents are not always aware if their child had a blood lead test. Information and reminders about blood lead testing should be distributed to parents of young children enrolled in Medicaid and frequently reviewed by healthcare providers.

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.

Understanding childhood lead poisoning preventive behaviors: the roles of self-efficacy, subjective norms, and perceived benefits

INTRODUCTION

Understanding individual and social influences on behaviors commonly recommended to prevent lead poisoning in children can guide more effective educational interventions.

METHODS

In-person interviews were conducted with primary caregivers (n = 380) of American Indian and White children aged 1 to 6 living in or near the Tar Creek Superfund site in northeastern Oklahoma. Caregivers' perceived health benefits, self-efficacy, and subjective norms were assessed for four lead poisoning prevention behaviors (i.e., annual blood lead testing, playing in safe areas, washing hands before eating, and dusting with a damp cloth).

RESULTS

Caregivers spoke with their own mothers, spouses, and other female family members most often when they had concerns or worries about taking care of their children. In multivariate models, subjective norms, perceived benefits, and self-efficacy were positively associated with the hand-washing and damp-dusting behaviors, while only self-efficacy was associated with playing in safe areas. None of the variables were found to have significant influence on the blood lead testing behavior.

CONCLUSIONS

Education programs should address individual level factors such as self-efficacy and perceived health benefits but also consider new strategies that incorporate a normative dimension to lead poisoning prevention.

Lead levels in Canadian children: Do we have to review the standard?

Research indicates that the blood lead levels that were once considered safe can adversely affect the neurodevelopment of children. The purpose of the present article is to review issues surrounding lead exposure in Canadian children, including sources, chronic low levels of exposure, and recommendations for prevention. Information was obtained through searches of MEDLINE and Web of Science using a combination of: "Canada" or "Canadian" plus "child" or "paediatrics" plus "lead" or "lead poisoning" or "blood lead". Centers for Disease Control and Prevention data and American peer-reviewed literature were also used. On-line Health Canada advisories (available since 1995), as well as relevant reports from nongovernmental organization and the media, were reviewed. The present review found that there has been limited surveillance of blood lead levels of Canadian children and, mainly, among high-risk groups. Harmful health effects may occur below the current standards and the threat of lead in consumer products remains. The current regulation seems to be inadequate to protect Canadian children.

Early behavioral effects of lead perinatal exposure in rat pups

Acoustic analysis of infants crying, a sensitive and selective index for measuring the effect of pre and perinatal lead exposure, may provide an early marker for central nervous system damage produced by the toxic. The present study evaluated the effects of exposure to low lead levels during perinatal and early postnatal periods on ultrasonic vocalization (USV), an early behavior of rat pups essential to their development. Non-sexually experienced females were gavaged daily with 8, 16 or 24 mg/kg of lead acetate or the control solution (1 ml/kg) for 30 days prior to breeding and until their pups were weaned. After crossover of dams, pups had been exposed to lead during pregnancy+lactation, pregnancy or lactation. The physiological variables measured on postnatal days 7 or 14 were USV, locomotion, rectal temperature, body weight and blood lead levels. Lead exposition during pregnancy+lactation, pregnancy or lactation induced a significant dose-dependent decrease of USV of 7-day-old pups. On the contrary, lead exposition during the different phases of pregnancy induced a significant dose-dependent increase of USV in 14-day-old rat pups. Blood lead levels varied from 5.7 to 36.5 microg/dl in pups. Body weight and temperature were not influenced by lead exposition. Lead-exposed 14-day-old pups were significantly more active. This study provides evidence of developmental changes in USV emission in rat pups exposed with low lead levels.

Prevalence of blood lead levels >or= 5 micro g/dL among US children 1 to 5 years of age and socioeconomic and demographic factors associated with blood of lead levels 5 to 10 micro g/dL, Third National Health and Nutrition Examination Survey, 1988-1994

OBJECTIVES

As part of an investigation into the impact of a potential revision in federal childhood lead poisoning prevention policy that would result in screening children for blood lead levels (BLLs) >or=5 micro g/dL rather than the current 10 micro g/dL, we analyzed the most recent available, nationally representative data to identify prevalence of BLLs >or=5 micro g/dL and socioeconomic and demographic characteristics of 1- to 5-year-old children with BLLs >or=5 but <10 micro g/dL.

METHODS

We performed statistical analyses on data from the Third National Health and Nutrition Examination Survey (NHANES III) (1988-1994) to describe trends in BLLs >or=5 micro g/dL overall and among subpopulations of children <6 years old and to compare risk factors for falling within 1 of 3 groups of children (those with BLLs >or=5 but <10 micro g/dL; >or=10 but <20 micro g/dL; and >or=20 micro g/dL) using the group reported as 0.7 to <5 micro g/dL as the referent.

RESULTS

Overall prevalence of BLLs >or=5 micro g/dL among 1- to 5-year-old children was 25.6%, although most (76%) of these children had BLLs <10 micro g/dL. Children with BLLs >or=5 micro g/dL included 46.8% of non-Hispanic black children, 27.9% of Mexican American children, and 18.7% of non-Hispanic white children; 42.5% of children in housing built before 1946, 38.9% of children in housing built between 1946 and 1973, and 14.1% of children in housing built after 1973 had BLLs >or=5 micro g/dL. Compared with non-Hispanic white children, non-Hispanic black children were 3 times more likely to have a BLL >or=5 but <10 micro g/dL, 7 times more likely to have a BLL of 10-20 micro g/dL, and 13.5 times more likely to have a BLL >or=20 micro g/dL. Similar increases in the association between risk factor and BLL were seen with respect to other known risk factors including age of housing, region of the country, and poverty.

CONCLUSIONS

The high prevalence of BLLs >or=5 micro g/dL overall and within US subpopulations will be an important variable in any change in screening and intervention criteria. However, most children with BLLs >or=5 micro g/dL are below the current intervention level of 10 micro g/dL. Exposure to lead from multiple sources is suggested by the prevalence of BLLs >or=5 micro g/dL but <10 micro g/dL among children with uncertain risk factors. The probable presence of one or more known risk factors for childhood lead poisoning increases as BLL increases.