Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID).

BACKGROUND: Prenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study's aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of selenium against mercury toxicity were also examined. METHODS: Participants (mean corrected age = 6.6 months) were part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), lead and mercury were measured in maternal blood during pregnancy, as well as in the cord blood. The Teller acuity card test (TAC) (n = 429) and the visual evoked potentials in a sub-group (n = 63) were used to estimate behavioural and electrophysiological visual acuity, respectively. Multivariable linear regression models were used to investigate the relationship between exposure to each contaminant and visual acuity measures, while controlling for potential confounders. Breastmilk selenium, which was available for about half of the TAC and VEP samples, was also taken into account in the mercury models as exploratory analyses. RESULTS: We observed no significant associations between exposure to any contaminants and TAC. Analyses revealed a negative trend (p values < 0.1) between cord blood lead and mercury and electrophysiological visual acuity, whereas PCB and PBDE showed no association. When adding breastmilk selenium concentration to the mercury models, this association became statistically significant for cord concentrations (ß = - 3.41, 95% CI = - 5.96,-0.86), but also for blood levels at 1st and 3rd trimesters of pregnancy (ß = - 3.29, 95% CI = - 5.69,-0.88). However, further regression models suggested that this change in estimates might not be due to adjustment for selenium, but instead to a change in the study sample. CONCLUSIONS: Our results suggest that subtle, but detectable alterations of infant electrophysiological visual acuity can be identified in a population prenatally exposed to low mercury concentrations. Compared to behavioural visual acuity testing, electrophysiological assessment may more sensitive in detecting visual neurotoxicity in relation with prenatal exposure to mercury.

Biomarkers in paediatric research and practice.

Children's health is, to a large extent, a function of their environment. Infectious agents remain the leading cause of death and disability in the world. In contrast, many of the new morbidities--asthma, intellectual impairments, behavioural problems, and cancer--are linked with industrial pollutants or other environmental influences. Our understanding of the risk factors for many diseases is incomplete, but it is widely recognised that disability and death result largely from interactions of environmental factors, broadly defined, and host susceptibility.

A side-by-side comparison of sampling methods for settled, indoor allergens.

Exposure to indoor allergens is associated with asthma, but there is no standardized sampling method for measuring allergens. We compared the association of measured allergen exposure and serum-specific IgE levels and the precision of three sampling methods (Cyclone, Mighty Mite, and Readivac II) to identify a standardized sampling method for indoor allergens. A random sample of 72 children, 5 to 17 years old, with doctor-diagnosed asthma who lived in the same residence >or=2 years were enrolled. Composite, side by side floor samples were obtained with all three methods. Dust allergen concentrations and serum-specific IgE levels were measured for Der f I, Fel d I, and Bla g I. Mean allergen concentration did not differ significantly by sampling method. Cat allergen was significantly correlated with serum-specific IgE for Cyclone (P=0.003) and Mighty Mite (P=0.008), but only marginally for Readivac II (P=0.07). Dust mite allergen was significantly correlated with serum-specific IgE for Readivac II (P=0.02) and Cyclone (P=0.038), but not for Mighty Mite (P=0.12). Cockroach allergen was not correlated with serum-specific IgE for any sampling method. In multiple linear regression, cat allergen was associated with serum-specific IgE for Cyclone (P=0.007) and Mighty Mite (P=0.02), but not for Readivac II (P=0.06). In contrast, dust mite allergen was marginally associated with serum-specific IgE for Readivac II (P=0.07), but not for Mighty Mite (P=0.64) or Cyclone (P=0.27). The Cyclone and Mighty Mite were more precise than Readivac II for cat allergen, but there was no difference for dust mite allergen (P>0.05). No single method is superior for measurement of indoor allergens. In general, cat allergen collected with the Cyclone was a better predictor of serum-specific IgE levels to Fel d I, whereas dust mite allergen collected with the Readivac II was a better predictor of serum-specific IgE levels to Der f I.

Contribution of residential exposures to asthma in us children and adolescents.

CONTEXT: Residential exposures are recognized risk factors for asthma, but the relative contribution of specific indoor allergens and their overall contribution to asthma among older children and adolescents in the United States are unknown. OBJECTIVE: To estimate the relative contributions, population-attributable risks, and costs of residential risk factors for doctor-diagnosed asthma. Design. Nationally representative, cross-sectional survey conducted from 1988 to 1994. SETTING AND PARTICIPANTS: A total of 5384 children who were 6 to 16 years old and participated in the National Health and Nutrition Examination Survey III, a survey of the health and nutritional status of children and adults in the United States. MAIN OUTCOME MEASURE: Doctor-diagnosed asthma, as reported by the parent. RESULTS: Five hundred three of 5384 children and adolescents (11.4%) had doctor-diagnosed asthma. After adjusting for age, gender, race, urban status, region of country, educational attainment of the head of household, and poverty, predictors of doctor-diagnosed asthma included a history of allergy to a pet (odds ratio [OR: 2.4; 95% confidence interval [CI]: 1.7, 3.3), presence of a pet in the household (OR: 1.5; 95% CI: 1.1, 2.1), and immediate hypersensitivity to dust mite (OR: 1.5; 95% CI: 1.05, 2.0), Alternaria (OR: 1.9; 95% CI: 1.3, 2.8), and cockroach allergens (OR: 1.4; CI: 1.04, 1.9). Family history of atopy (OR: 1.7; 95% CI: 1.1, 2.7) and diagnosis of allergic rhinitis (OR: 2.1; CI: 1.1, 3.7) were also predictors for asthma. The population-attributable risk of having 1 or more residential exposures associated with doctor-diagnosed asthma was 44.4% (95% CI: 29-60), or an estimated 2 million excess cases. The attributable cost of asthma resulting from residential exposures was $405 million (95% CI: $264-$547 million) annually. CONCLUSIONS: The elimination of identified residential exposures, if causally associated with asthma, would result in a 44% decline in doctor-diagnosed asthma among older children and adolescents in the United States.

Residential exposures associated with asthma in US children.

OBJECTIVE: Residential exposures are recognized risk factors for childhood asthma, but the relative contribution of specific risk factors and the overall contribution of housing to asthma in US children is unknown. The objective of this study was to identify risk factors and estimate the population attributable risk of residential exposures for doctor-diagnosed asthma for US children. METHODS: A cross-sectional survey was conducted from 1988 to 1994. Survey participants were 8257 children who were <6 years old and who participated in the Third National Health and Nutrition Examination Survey, a survey of the health and nutritional status of children and adults in the United States. The main outcome measure was doctor-diagnosed asthma, as reported by the parent. RESULTS: Six percent of children had doctor-diagnosed asthma. The prevalence of asthma was higher among boys (6.7%) than girls (5.1%) and was higher among black children (8.9%) than white children (5.2%). Risk factors for doctor-diagnosed asthma included a family history of atopy (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.5, 3.1), child's history of allergy to a pet (OR: 24.2; 95% CI: 8.4, 69.5), exposure to environmental tobacco smoke (OR: 1.8; 95% CI: 1.2-2.6), use of a gas stove or oven for heat (OR: 1.8; 95% CI: 1.02-3.2), and presence of a dog in the household (OR: 1.6; 95% CI: 1.1, 2.3). The population attributable risk of >/=1 residential exposure for doctor-diagnosed asthma in US children <6 years old was 39.2%, or an estimated 533 000 excess cases, whereas having a family history of atopy accounted for 300 000. The attributable cost of asthma as a result of residential exposures for children <6 years old was $402 million (95% CI: $296-$507 million) annually. CONCLUSIONS: The elimination of identified residential risk factors, if causally associated with asthma, would result in a 39% decline in doctor-diagnosed asthma among US children <6 years old.

Trends and patterns of playground injuries in United States children and adolescents.

OBJECTIVE: To determine the prevalence, trends, and severity of injuries attributable to playground falls relative to other common unintentional mechanisms that resulted in an emergency department (ED) visit in the United States. DESIGN AND SETTING: Data from the emergency subset of the National Hospital Ambulatory Medical Care Survey collected from 1992 to 1997 for children <20 years. METHODS: Injury rates and 95% confidence intervals (CIs) were estimated and injury severity scores were computed. RESULTS: There were 920551 (95% CI: 540803 to 1300299) ED visits over the 6-year study period by children and adolescents that were attributable to falls from playground equipment. The annual incidence of visits for playground injuries did not significantly decrease over the course of the study (187000 to 98000, P =.053). Injury visits for playground falls were twice as prevalent as pedestrian mechanisms, but they were less prevalent than visits for motor vehicle-- and bicycle-related injuries. A larger proportion of playground falls resulted in "moderate-to-severe" injury than did bicycle or motor vehicle injuries. Children aged 5 to 9 years had the highest number of playground falls (P =.0014). Playground falls were most likely to occur at school compared to home, public, and other locations (P =.0016). CONCLUSIONS: Playground injury emergency visits have not significantly declined and remain a common unintentional mechanism of injury. Injury visits for playground falls were proportionally more severe than injury visits attributable to other common unintentional mechanisms. Interventions targeting schools and 5- to 9-year-old children may have the greatest impact in reducing emergency visits for playground injuries.

Long-term effect of dust control on blood lead concentrations.

BACKGROUND: Dust control is recommended to prevent children's exposure to residential lead hazards, but the long-term effect of dust control on children's exposure to environmental lead is unknown. OBJECTIVE: To determine the effect of dust control on children's exposure to lead, as measured by blood lead concentration at 48 months of age. DESIGN: A randomized, controlled trial. Setting. Rochester, New York. PARTICIPANTS: A total of 275 urban children were randomized at 6 months of age; 189 (69%) were available for the 48-month follow-up blood test. Intervention. Children and their families were randomly assigned to an intervention group that received cleaning equipment and up to 8 visits by a trained lead hazard control advisor or to a control group. The intervention was terminated when the children were 24 months of age. OUTCOME MEASURES: Geometric mean blood lead concentration and prevalence of elevated blood lead concentration (ie, >/=10 microg/dL, >/=15 microg/dL, and >/=20 microg/dL), by group assignment. RESULTS: For children with 48-month blood tests, baseline geometric mean blood lead concentrations were 2.8 microg/dL (95% confidence interval [CI]: 2.6, 3.0); there were no significant differences in baseline characteristics or lead exposure by group assignment. At 48 months of age, the geometric mean blood lead was 5.9 microg/dL (95% CI: 5.3, 6.7) for the intervention group and 6.1 microg/dL (95% CI: 5.5,6.9) for the control group. The percentage of children with a 48-month blood lead >/=10 microg/dL, >/=15 microg/dL, and >/=20 microg/dL was 19% versus 19%, 2% versus 9%, and 1% versus 2% in the intervention and control groups, respectively. CONCLUSIONS: We conclude that dust control, as performed by families and in the absence of lead hazard controls to reduce ongoing contamination from lead-based paint, was not effective in preventing children's exposure to residential lead hazards.

Barriers to asthma care in urban children: parent perspectives.

BACKGROUND: Despite improved treatment regimens for asthma, the prevalence and morbidity from asthma are increasing, especially among underserved, minority children. OBJECTIVE: The purpose of this study was to identify barriers to the treatment of asthma among urban, minority children as perceived by parents. METHODS: Parents were recruited from 4 schools located in low-income, urban areas with high rates of asthma hospitalizations. Focus groups involving parents of children 5 to 12 years old with asthma were conducted using a standardized questionnaire. Parents' comments were analyzed to identify barriers, and 3 independent raters coded parents' comments to assess reliability of interpretation. RESULTS: Forty parents who represented 47 children participated in the focus groups. All parents described their racial background as black. Parents' average age was 36.8 years, 92% were females, 70% were nonmarried, and 38% had less than a high school education. Forty-five percent of children had intermittent or mild asthma and 55% had moderate to severe asthma. The most frequent types of barriers identified by parents were patient or family characteristics (43%), followed by environmental (28%), health care provider (18%), and health care system (11%). Parents were specifically concerned about the use, safety and long-term complications of medications, the impact of limitation of exercise on their child's quality of life, and their own quality of life. CONCLUSIONS: In contrast with the widespread beliefs that access to medical care, health insurance, and continuity of care are the major barriers to quality asthma care, the barriers most frequently reported by parents were related to patient and family characteristics, health beliefs, or to their social and physical environment. To improve asthma management and health outcomes for urban, minority children with asthma, it is critical to tailor education about asthma and its treatment, and address quality of life issues for both children and parents.

Childhood injuries and deaths due to falls from windows.

BACKGROUND: Unintentional injuries are the leading cause of death in children, and falls are the most common type of unintentional injury in the US. The incidence of falls from windows, a common cause of death in urban areas, has not been described outside major cities such as New York and Chicago, and rates in urban and suburban areas have not been compared. OBJECTIVE: To estimate the incidence and identify the population at risk for falls from windows among children in Hamilton County, Ohio. DESIGN: Retrospective case series identified using Cincinnati Children's Hospital Medical Center (CHMC) Trauma Registry. SETTING: Hamilton County, Ohio, which has urban and nonurban areas. PARTICIPANTS: Children less than 15 years old residing in Hamilton County, Ohio, presenting to CHMC in Cincinnati, Ohio, after a fall from a window between January 1, 1991, and December 31, 1997. OUTCOME MEASURE: Annual incidence by age, race, gender, and residence of those who fell from windows. RESULTS: Over the 7-year study period, 86 (6.3%) of 1,363 falls were from windows. The mortality rate for falls from windows was 4.7%, compared to 0.07% for all other falls presenting to CHMC (P<.0001). Children 0-4 years old had a higher rate of falls than children aged 5-14 (14.6/100,000 vs. 2.0/100,000) (P<.0001). Males were twice as likely to fall as females (P<.016), and black children were three times more likely to fall than non-black children (P<.002). The incidence of falls in the city of Cincinnati was four times that of the non-urban area (P<.0002). CONCLUSIONS: Injuries from falls from windows are a public health problem in Hamilton County, Ohio, especially for young, urban children.

Program directors' perspectives on federally funded fellowship training in primary care research.

PURPOSE: To describe the organization, models of training, and institutional impact of National Research Service Award fellowship programs in primary care research. METHOD: Survey of 25 directors of currently-funded and former training sites. RESULTS: Twenty-four program directors (96%) completed the survey. Programs allocated 39% of fellows' time to course work leading to an advanced degree or other didactic instruction, and 40% of time to the conduct of research. Collaborations with other training programs within the institution occurred at 83% of sites. Programs commonly (54%) or exclusively (42%) relied on a research model of "early research independence" in which the fellow defined an area of research interest, rather than an "apprenticeship" model in which the fellow worked in a senior investigator's research area. These programs enriched the local academic environment, but required extensive financial subsidies. The high costs of training often had adverse impacts on recruitment and other components of the training process. CONCLUSION: Research training programs in primary care often substitute acquisition of advanced degrees for early immersion in research. The "early independence" model of research differs from fellowships in the medical specialties, and requires further study to assess its effectiveness. The need to subsidize training costs poses substantial problems for the institutions that host these fellowship programs.

Cognitive deficits associated with blood lead concentrations <10 microg/dL in US children and adolescents.

OBJECTIVE: Lead is a confirmed neurotoxicant, but the lowest blood lead concentration associated with deficits in cognitive functioning and academic achievement is poorly defined. The purpose of the present study was to examine the relationship of relatively low blood lead concentrations-especially concentrations <10 micrograms per deciliter (microg/dL)--with performance on tests of cognitive functioning in a representative sample of US children and adolescents. METHODS: The authors used data from the Third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 to 1994, to assess the relationship between blood lead concentration and performance on tests of arithmetic skills, reading skills, nonverbal reasoning, and short-term memory among 4,853 children ages 6-16 years. RESULTS: The geometric mean blood lead concentration for children n the study sample was 1.9 microg/dL; 172 (2.1%) had blood lead concentrations > or =10 microg/dL. After adjustment for gender, race/ethnicity, poverty, region of the country, parent or caregiver's educational level, parent or caregiver's marital status parent, serum ferritin level, and serum cotinine level, the data showed an inverse relationship between blood lead concentration and scores on four measures of cognitive functioning. For every 1 microg/dL increase in blood lead concentration, there was a 0.7-point decrement in mean arithmetic scores, an approximately 1-point decrement in mean reading scores, a 0.1-point decrement in mean scores on a measure of nonverbal reasoning, and a 0.5-point decrement in mean scores on a measure of short-term memory. An inverse relationship between blood lead concentration and arithmetic and reading scores was observed for children with blood lead concentrations lower than 5.0 microg/dL. CONCLUSION: Deficits in cognitive and academic skills associated with lead exposure occur at blood lead concentrations lower than 5 microg/dL.

Physiologic stability of newborns during cup- and bottle-feeding.

BACKGROUND: To prevent breastfeeding problems, cup-feeding has been recommended as a method of providing medically necessary supplemental feedings to breastfed infants. OBJECTIVES: To compare amounts ingested, administration time, and infant physiologic stability during cup-, bottle-, and breastfeeding. DESIGN/METHODS: A total of 98 term, healthy newborns were randomized to either cup-feeding (n = 51) or bottle-feeding (n = 47). The heart (HR), respiratory (RR), and oxygen (O(2)) saturation rates were monitored on these infants and 25 breastfed newborns during 1 feeding. Differences in amounts ingested and administration times were evaluated with t tests and physiologic data with repeat measures analysis of variance. RESULTS: There were no significant differences in administration time, amounts ingested or overall HR, RR, and (O(2)) saturation rates, between cup and bottle groups. Breastfed infants had longer administration times and lower overall HR, RR, and higher O(2) saturation as compared with cup- and bottle-fed infants. CONCLUSIONS: Administration times, amounts ingested, and infant physiologic stability do not differ with cup- and bottle-feeding. Breastfeeding takes longer than cup- or bottle-feeding, but infants experience less physiologic variability. These data support cup-feeding as an alternative to bottle-feeding for supplying supplements to breastfed infants.

Association of dental caries and blood lead levels.

CONTEXT: Experiments show that dental caries rates are higher among lead-exposed animals, but this association has not been established in humans. OBJECTIVE: To examine the relationship between blood lead levels and dental caries. DESIGN: Cross-sectional survey conducted from 1988 to 1994 that included a dental examination and venipuncture blood lead assay. SETTING AND PARTICIPANTS: A total of 24901 persons aged 2 years and older who participated in the Third National Health and Nutrition Examination Survey, which assessed the health and nutritional status of children and adults in the United States. MAIN OUTCOME MEASURES: For children aged 2 to 11 years, the sum of decayed and filled deciduous or primary surfaces; for persons aged 6 years and older, the sum of decayed and filled permanent surfaces; for those 12 years and older, the sum of decayed, missing, and filled surfaces. RESULTS: The log of blood lead level was significantly associated with the number of affected surfaces for both deciduous and permanent teeth in all age groups, even after adjusting for sociodemographic characteristics, diet, and dental care. Among children aged 5 to 17 years, a 0.24-micromol/L (5-microg/dL) change in blood lead level was associated with an elevated risk of dental caries (odds ratio, 1.8; 95% confidence interval, 1.3-2.5). Differences in blood lead level explained some of the differences in caries prevalence in different income levels and regions of the United States. We estimated the population attributable risk of lead exposure to be 13.5% and 9.6% of dental caries occurring in 5- to 17-year-olds exposed to the high and moderate levels, respectively. CONCLUSIONS: Environmental lead exposure is associated with an increased prevalence of dental caries in the US population. Findings may help explain the distribution of caries by income and region of the United States.

Primary prevention of childhood lead exposure: A randomized trial of dust control.

BACKGROUND: Dust control is recommended as one of the primary strategies to prevent or control children's exposure to residential lead hazards, but the effect of dust control on children's blood lead levels is poorly understood. OBJECTIVE: To determine the effectiveness of dust control in preventing children's exposure to lead, as measured by blood lead levels, during their peak age of susceptibility. DESIGN: A randomized, controlled trial. SETTING: Rochester, NY. PARTICIPANTS: A total of 275 urban children were randomized at 6 months of age, of whom 246 (90%) were available for the 24-month-old follow-up visit. INTERVENTIONS: Children and their families were randomly assigned to an intervention group (n = 140), which received cleaning equipment and up to eight visits by a dust control advisor, or a control group (n = 135). OUTCOME MEASURES: Geometric mean blood lead levels and prevalence of elevated blood lead levels (ie, >10 microg/dL, 15 microg/dL, and 20 microg/dL). RESULTS: At baseline, children's geometric mean blood lead levels were 2.9 microg/dL (95% confidence interval [CI] = 2.7, 3.1); there were no significant differences in characteristics or lead exposure by group assignment, with the exception of water lead levels. For children in the intervention group, the mean number of visits by a dust control advisor during the 18-month study period was 6.2; 51 (36%) had 4 to 7 visits, and 69 (49%) had 8 visits. At 24 months of age, the geometric mean blood lead was 7.3 microg/dL (95% CI = 6.6, 8.2) for the intervention group and 7.8 microg/dL (95% CI = 6.9, 8. 7) for the control group. The percentage of children with a 24-month blood lead >/=10 microg/dL, >/=15 microg/dL, and >/=20 microg/dL was 31% versus 36%, 12% versus 14%, and 5% versus 7% in the intervention and control groups, respectively. CONCLUSIONS: We conclude that dust control, as performed by families and in the absence of lead hazard controls to reduce ongoing contamination from lead-based paint, is not effective in the primary prevention of childhood lead exposure.

Efficacy of informational letters on hepatitis B immunization rates in university students.

A randomized, controlled trial was conducted at a private university to determine whether students who received an informational letter (n = 366) would be more likely to receive a hepatitis B vaccination than students in a control group (n = 366). Surveys were conducted to determine the students' reasons for deciding to be vaccinated. Rates of hepatitis B immunization were significantly higher among students assigned to the intervention group (10.7%) than among the control group (1.9%). Vaccinated students were more likely than unvaccinated students to report having had 3 or more sexual partners in the past 6 months. Students at higher risk for hepatitis B infection were more likely than others to be vaccinated. Although the overall rate of immunization was low, informational letters about the hepatitis B virus and vaccine were found to be efficacious in increasing hepatitis B immunization rates among students in the setting of a concurrent educational campaign.

Risk factors for the early acquisition of human herpesvirus 6 and human herpesvirus 7 infections in children.

OBJECTIVE: Human herpesviruses 6 and 7 (HHV-6 and HHV-7) are common infections in children, but risk factors for their early acquisition have not been described. METHODS: Excess sera from children 12 to 31 months of age enrolled in a cross-sectional, random survey were tested for human herpesviruses 6 and 7 infection, as measured by using immuno-blot and immunofluorescence assays. RESULTS: Of 164 children 131 (80%) had antibody to HHV-6, and 79 (47%) of 167 had antibody to HHV-7. In logistic regression analysis low income [odds ratio (OR), 2.9; 95% confidence intervals (CI), 1.02 to 8.7] and having more than 1 sibling (OR=2.1, 95% CI=0.9 to 5.1) were risk factors for HHV-6 infection after adjusting for age, whereas month of test (OR=2.7, 95% CI=1.3 to 5.9) and Black race (OR=2.0, 95% CI=0.9, 4.6) were associated with a higher prevalence of HHV-7 infection. In contrast having ever been breast-fed appeared to protect against HHV-7 infection (OR=0.5, 95% CI=0.3 to 1.1). CONCLUSIONS: Despite studies linking both HHV-6 and HHV-7 with exanthem subitum, risk factors for the early acquisition of HHV-6 and HHV-7 are distinct. Subsequent studies investigating the transmission of HHV-6 should explore family size and other factors associated with poverty, whereas breast-feeding should be examined as a protective factor for HHV-7 infection.

The contribution of lead-contaminated house dust and residential soil to children's blood lead levels. A pooled analysis of 12 epidemiologic studies.

In 1992, the U.S. Congress passed the Residential Lead-Based Paint Hazard Reduction Act, which requires the promulgation of health-based dust lead and soil lead standards for residential dwellings to prevent undue lead exposure in children. Unfortunately, the levels of lead in house dust and soil that are associated with elevated blood lead levels among U.S. children remain poorly defined. This pooled analysis was done to estimate the contributions of lead-contaminated house dust and soil to children's blood lead levels. The results of this pooled analysis, the most comprehensive existing epidemiologic analysis of childhood lead exposure, confirm that lead-contaminated house dust is the major source of lead exposure for children. These analyses further demonstrate that a strong relationship between interior dust lead loading and children's blood lead levels persists at dust lead levels considerably below the U.S. Department of Housing and Urban Development's current postabatement standards and the Environmental Protection Agency's guidance levels. Finally, these analyses demonstrate that a child's age, race, mouthing behaviors, and study-site specific factors influence the predicted blood lead level at a given level of exposure. These data can be used to estimate the potential health impact of alternative health-based lead standards for residential sources of lead exposure.

Environmental exposures to lead and urban children's blood lead levels.

Lead-contaminated water, soil, and paint have been recognized as potential sources of children's lead exposure for decades, but their contributions to lead intake among urban children remain poorly defined. This analysis was undertaken to estimate the relationship of environmental lead exposures to lead intake among a random sample of urban children, adjusted for exposure to lead-contaminated house dust. Analyses of 183 urban children enrolled in a random sample, cross sectional study were conducted. Children's blood and multiple measures of household dust, water, soil, and paint were analyzed for lead, and interviews were conducted to ascertain risk factors for childhood lead exposure. Environmental sources of lead, including house-dust, soil lead, and water lead, were independently associated with children's blood lead levels. In contrast, paint lead levels did not have a significant effect on blood lead levels after adjusting for other environmental exposures. An increase in water lead concentration from background levels to 0.015 mg/L, the current EPA water lead standard, was associated with an increase of 13.7% in the percentage of children estimated to have a blood lead concentration exceeding 10 micrograms/dL; increasing soil lead concentration from background to 400 micrograms/g was estimated to produce an increase of 11.6% in the percentage of children estimated to have a blood lead level exceeding 10 micrograms/dL, and increasing dust lead loading from background to 200 micrograms/ft2 is estimated to produce an increase of 23.3% in the percentage of children estimated to have a blood lead level exceeding 10 micrograms/dL. These data support the promulgation of health-based standards for lead-contaminated dust and soil and the progressive lowering of standards for lead-contaminated water as the definition of undue lead exposure has been modified.