Blood Lead Screening Research Articles

A study of the distribution of urban environmental lead levels in Cape Town, South Africa

Epidemiological studies which have attempted to quantify the relationship between environmental lead and blood lead levels have been beset by numerous methodological problems, one of which has been the difficulty in assessing environmental exposure to lead. In Cape Town, South Africa, a comprehensive environmental lead monitoring programme was instituted in an inner city suburb where a blood lead screening study was in progress. The objective of the study was to examine the spatial and temporal variation in environmental lead levels, and to examine the role of potential influencing factors such as traffic. Results revealed substantial intra-urban variations in air lead levels, with annual means varying from less than 0.5 to over 2 μg/m3 at individual sites. Traffic density and the distance from heavily trafficked roads were important influencing factors within the area. Considerable seasonal as well as daily variations in air lead levels were also documented, and air lead levels were positively associated with dust lead levels. The spatial and temporal variations in environmental lead have implications for air monitoring strategies and epidemiological studies concerned with the relationship of exposure to lead and the health impact on populations. Micro variations in exposure need to be taken into account in assessing exposure to environmental lead in epidemiological studies, in light of the considerable variations which may occur.

Blood Lead Screening Practices Among US Pediatricians

In 1991, the Centers for Disease Control and Prevention (CDC) decreased the blood lead level of concern to 10 micrograms/dL (0.48 mumol/L) and recommended universal screening. Because these guidelines continue to provoke controversy, we conducted a study to: 1) estimate the proportion of pediatricians who are members of the American Academy of Pediatrics (AAP) who report screening for elevated blood lead levels; 2) describe their clinical practices regarding screening for elevated blood lead levels; 3) compare attitudes of universal screeners, selective screeners, and nonscreeners; and 4) identify characteristics of pediatricians who universally screen. Confidential, cross-sectional survey of a nationally representative random sample of 1610 pediatricians conducted through the AAP Periodic Survey. The study included 1035 responders (64% response rate). Analysis was limited to the 734 pediatricians who provide well-child care (ie, primary-care pediatricians). Fifty-three percent of pediatricians reported screening all their patients aged 9 to 36 months, 39% reported screening some, and 8% reported screening none. Among those who screen, 96% use a blood lead assay. The primary risk factors for which selective screeners screen are: history of pica (94%); living in an older home with recent renovations (92%); living in an older home with peeling paint (93%); and having a sibling who had an elevated blood lead level (88%). Among primary-care pediatricians, 73% agree that blood lead levels > or = 10 micrograms/dL should be considered elevated, and 16% disagree. However, 89% of primary-care pediatricians believe that epidemiologic studies should be performed to determine which communities have high proportions of children with elevated blood lead levels, and 34% of primary-care pediatricians believe that the costs of screening exceed the benefits. Three years after the Centers for Disease Control and Prevention issued new guidelines for the management of elevated blood lead levels, a slight majority of primary-care pediatricians in the United States who are members of the AAP report that they universally screen their appropriately aged patients, while most of the remaining pediatricians report screening high-risk patients. Many pediatricians may want additional guidance about circumstances under which selective screening should be considered.

A co-operative approach to risk management in an active lead/zinc smelter community

Trail, Canada has been the site of a large lead/zinc smelting facility since 1916. In mid 1990, the Trail Community Lead Task Force was established and given responsibility for developing a strategy to reduce children's blood lead levels. With funding from the provincial government, the smelting company and the municipal government, the Task Force has carried out blood lead screening, case management, community education, exposure pathways modelling and remediation trials. The decline in children's blood lead levels appeared to accelerate following the implementation of these programmes. The average blood lead in Trail children aged 6-72 months fell 14% from the autumn of 1991 to autumn of 1992, whereas for the previous 16 years, the average annual decline had been about 4%. In subsequent years, blood lead levels have appeared to plateau. Throughout the 5-year history of the Task Force, its members have demonstrated a strong sense of common purpose and have worked co-operatively to reach consensus on most issues.

Identification of Children At Risk for Lead Poisoning: An Evaluation of Routine Pediatric Blood Lead Screening in an HMO-Insured Population

To estimate the prevalence of elevated blood lead levels in children receiving well-care checkups; and to evaluate the effectiveness of certain key risk factors in detecting children at higher risk for elevated blood lead levels. Cross-sectional study. Two facilities of the Kaiser Permanente Medical Care Program (KPMCP) health maintenance organization (HMO), northern California region. Six hundred thirty-six children, aged 12 to 60 months, who were seen at four KPMCP facilities in two subregions for a well-care checkup from September 1991 through August 1992. Blood samples were collected from each child and analyzed for lead content. Participating parents completed a questionnaire that included questions recommended by the Centers for Disease Control and Prevention (CDC) about the child's and the parents' lead exposure via home, workplace, and hobbies. Ninety-six percent of the children had blood lead levels under 10 micrograms/dL. Blood lead levels declined with increasing age and were higher for black children compared with whites. Age of residential housing, mother's education, and residence in an old house with peeling paint had low sensitivity and positive predictive value for identifying children with blood lead levels over 10 micrograms/dL. Universal routine screening for elevated blood lead levels in children in an employed, HMO-insured population is not warranted on grounds of prevalence. Responses to CDC questions do not effectively identify high-risk children in this population.

Childhood blood lead screening: Addressing the laboratory issues

We have assessed the functional activity of three common sequence variants of human lipoprotein lipase (LPL). Two of these, Asn291Ser and Asp9Asn arise from missense mutations while the third, Ser447Ter, derives from a nonsense mutation, truncating LPL by two residues. As previous in vitro studies have produced conflicting results, we have re-analyzed the catalytic function of these variants using the COS cell transfection system, under optimized and standardized experimental protocols. We found the Asn291Ser variant to manifest with a decrease in catalytic activity (57% of normal) due to a reduction in secretion and stability of the active homodimeric form. The Asp9Asn variant also showed a significant decrease in catalytic activity (85% of normal), but this was found to be due to a decreased rate of secretion only, as the homodimeric form was stable. The findings for these mutants contrasted with those of the Ser447Ter truncation variant which proved to be catalytically normal; this variant also manifested normal homodimer stability. The truncated variant did however, present with a higher total secreted mass level (131%) than control LPL. This was most likely due to enhanced secretion of the monomeric form. None of these mutations exhibited defects in binding affinity to cell surface proteoglycans. Each of these variants deviated significantly from normal as regards to their secreted activity or mass levels in the COS cell transfection system.

Childhood blood lead screening: What are the pros and cons?

Mutations in human lipoprotein lipase (LPL) gene are potential risk factors for susceptibility to coronary artery disease (CAD). The objectives of this study were to determine the influence LPL mutations Asn291Ser and Ser447Ter on plasma lipid levels, regression and progression of CAD, clinical events rate, and response to fluvastatin therapy in the Lipoprotein and Coronary Atherosclerosis Study (LCAS) population. LCAS is a double blind, randomized, placebo-controlled study designed to test the influence of fluvastatin on progression or regression of CAD. The Asn291Ser and Ser447Ter genotypes were determined by polymerase chain reaction (PCR) and restriction enzyme digestion. Fasting plasma lipid profiles were measured and quantitative coronary angiography was performed at baseline and 2.5 years following randomization. Fatal and non-fatal cardiovascular events during the follow-up period were recorded. A total of 4% (14/363) and 18% (62/352) of the subjects had the Asn291Ser and Ser447Ter mutations, respectively. Overall, there was no statistically association between the Asn291Ser and Ser447Ter mutations and the baseline or final mean plasma levels of lipids, number of coronary lesions, total occlusions, the mean minimal lumen diameter (MLD) stenoses and the clinical events rate. However, patients with the Ser447Ter variant had a slightly higher baseline high density lipoprotein-cholesterol (HDL-C) level (46.2±12 vs 43.2±11, P=0.057), less increase in plasma HDL levels in response to fluvastatin therapy (3 vs 11%, P=0.056) and a higher cardiovascular events rate (23 vs 13%, P=0.056). Thus, the Ser447Ter variant had a modest influence on plasma HDL levels and the rate of cardiovascular events. These changes were of borderline statistical significance. Neither the Ser447Ter nor the Asn291Ser mutation had a major impact on susceptibility to CAD, progression or regression of CAD, clinical events rate or response to fluvastatin therapy in LCAS population.

Blood collection and analytical considerations in blood lead screening in children

Blood collection and analytical considerations in blood lead screening in children

Childhood lead poisoning in 1994

To the Editor. —According to Drs Goldman and Carra, 1 The US strategy [to prevent childhood lead poisoning] must begin to focus more than ever on poor, nonwhite, and inner-city children. Perhaps, instead of universal screening, data... indicate the need for a more targeted approach. But, compelled by the Centers for Disease Control and Prevention (CDC) 1991 recommendation for universal blood screening of all young children for lead poisoning, one state after another has passed laws requiring universal childhood blood lead testing. Delaware is the most recent state to pass such a law, requiring all children to have blood lead screening performed at least once, preferably around the age of 1 year. Without lead screening, the child would not be admitted to day care; or if the child has reached 5 years of age without having a blood lead level checked, he or she would not be admitted to

Comparability of Capillary and Venous Blood Samples for Lead Screening

To the Editor. —To achieve the goal of blood lead screening for all children aged 6 months to 6 years, 1 testing should be easy to perform, widely available, inexpensive, and reliable. Specimens are more easily obtained from children by fingerstick than by venipuncture. However, increased opportunity for contamination of capillary specimens has raised concerns about their reliability. Dr Schlenker and colleagues 2 compared capillary and venous blood lead levels in children and showed that between 0% and 5% (depending on sampling protocol) of the capillary results were false positives and 1% to 8% false negatives. 2 These percentages were referred to as and false-negative rates, which may lead to confusion. For example, the term false-positive rate traditionally has meant the percentage of false positives in the total positives (false positives/[false positives + true positives]). 3 Only this statistic has predictive value for determining the significance of a positive test.

Lead Poisoning Risk Assessment: Blood Lead Screening

The Centers for Disease Control and Prevention (CDC) lowered the blood lead level (BPb) considered a toxic risk to children from 25 mcg/dL to 10 mcg/dL in Oct 1991.

Long-Term Trends in Blood Lead Levels Among Children in Chicago: Relationship to Air Lead Levels

To evaluate trends in blood lead levels among children in Chicago from 1968 through 1988, and to determine the impact of the changes in the Centers for Disease Control and Prevention (CDC) blood lead level of concern. We reviewed a systematic sample of blood lead screening records of the Chicago Department of Health Laboratory for high-risk children aged 6 months to 5 years. Median blood lead levels for each quarter of the years 1974 through 1988 were determined and regressed against mean air lead levels recorded at air-monitoring stations in Chicago during the same period. Median blood lead levels declined from 30 micrograms/dL in 1968 to 12 micrograms/dL in 1988, and were strongly associated with declining average air lead levels (r = .8, P < .001) from 1974 through 1988. A regression model using log-transformed data predicted a decline of 0.56 microgram/dL in the median blood lead level with each 0.1 microgram/m3 decline in the mean air lead level when the air lead level was near 1.0 microgram/m3; the predicted slope was steeper at lower air lead levels. Despite the nearly 20-fold reduction in air lead levels, the median blood lead level of 12 micrograms/dL in 1988 indicates substantial continuing lead exposure. The CDC blood lead level of concern was lowered twice from 1968 to 1988, but due to the decline in blood lead levels, fewer than 30% of the children were above the level of concern throughout most of the study. Although substantial lead exposure persists in Chicago, reductions in airborne lead emissions seem to have contributed to a long-term decline in the median blood lead level of high-risk Chicago children.

Lead Poisoning Among Low-Income Children in Orange County, California

To estimate the prevalence of elevated lead levels among children in Orange County, California, and to evaluate the appropriateness of a universal pediatric blood lead screening policy in this community. Venous blood lead testing was conducted and results were analyzed according to seven blood lead strata ranging from less than 0.50 mumol/L (10 micrograms/dL) to 3.35 mumol/L (70 micrograms/dL) or higher. A cost analysis of the lead-testing program in Orange County was conducted. Children meeting poverty eligibility criteria and attending the Child Health and Disability Prevention Program, the state's implementation of the federal Early and Periodic Screening, Diagnosis and Treatment (EPSDT) services program. A total of 5115 Orange County children between 12 and 72 months of age using EPSDT services from March through December 1992. Blood lead levels and associated costs of the testing program stratified by level of blood lead elevation. Blood lead levels of 0.50 mumol/L (10 micrograms/dL) or higher were found in 371 children (7.25%; 95% confidence interval, 6.66% to 7.85%), but only six children (0.12%; 95% confidence interval, 0.04% to 0.20%) had elevations greater than 1.20 mumol/L (25 micrograms/dL). Five children (83.3%) had histories of lead consumption unrelated to ingestion of lead-containing paint but related to the use of lead-containing folk remedies and cooking utensils. Costs for detection of children with blood levels elevated to 0.50 mumol/L (10 micrograms/dL) or higher was $310 per child and for levels of 1.20 mumol/L (25 micrograms/dL) or higher was $19,139 per child. These data suggest that lead poisoning is not a major public health problem among Orange County children and detection of infrequent cases would involve a high cost per child. In jurisdictions with newer housing, initial screening for a history of possible lead exposure alone may offer reasonable efficacy that is cost-effective. The scope of lead-testing programs should be determined according to local needs and conditions.

Inappropriate blood lead level screening

We are concerned that venous blood lead screening in children is being applied inappropriately. Molina Medical Centers is a managed care organization that provides primary care and preventive services to Medicaid beneficiaries in California. The California Department of Health Services, through the Child Health and Disability Prevention Program, mandated venous blood lead testing in all Medicaid beneficiaries between 1 and 6 years of age who had not previously been tested.

Lead exposure among automobile radiator repair workers and their children in New York City.

Despite a comprehensive Occupational Safety and Health Administration lead standard, exposure to lead continues in many industries. This paper describes a blood lead screening and education program for automobile radiator repair workers and their families in New York City. Results showed that 67% of automobile radiator repair workers (n = 62) in 89% of the shops tested (n = 24) had blood lead levels in excess of 25 micrograms/dl. The vast majority of workers had never been tested previously, and none had received health and safety training regarding occupational lead exposure. Although none of the workers' children's blood lead levels were in excess of then-current guidelines, several had levels which may be associated with subclinical toxicity and in excess of the revised Centers for Disease Control guidelines of 10 micrograms/dl. This project demonstrates that lead exposure in the automotive radiator repair industry continues to be widespread and that local health departments can assist in hazard identification and remediation.

Blood lead screening in Ontario children: Blood lead and free erythrocyte protoporphyrin levels

A blood lead survey was conducted on samples from 2459 children aged 3–6 years to determine the prevalence of lead poisoning in children of this age in the Province of Ontario. Lead poisoning, defined as a blood lead concentration ⩾ 1.21 μmol l −1 (25 μg dl −1), was found in 26 subjects (1.1% of the samples). The mean blood lead concentration for children from southern Ontario was 0.50 μmol l −1, and for those from northern Ontario it was 0.37 μmol l −1. Stringent quality controls and independent cross-checks of finger-prick capillary blood sampling were employed in the study. The free erythrocyte protoporphyrin levels were also monitored to detect the presence of iron deficiency in the children.

Epidemiological monitoring of environmental lead exposures in California State Hospitals

Blood lead screening of 8062 state hospital residents in California revealed 143 residents with excessive lead levels (≥ 30 μg/dL). This screening was part of the Childhood Lead Project and was performed in 1978. The purpose of this study was to identify “critical” lead sources in California State Hospitals. Accurate identification is crucial if subsequent abatement programs are to be effective. The strategy involved the following sequence of steps: 1) Selection of cases based on blood lead and erythrocyte protoporphyrin screening. 2) Determination of pica habits and environmental exposures through interviews with ward's staff and/or parents. 3) Measurement of lead levels in environmental samples reflecting exposures. 4) Interpreting these data in order to identify critical lead sources. 5) Reducing exposure to critical lead sources. 6) Following up of cases and controls to validate the effects of this strategy. A group of 36 lead-burdened cases with pica (30–60 μg Pb/dL blood) and 36 matched controls (PbN less than 20 μg/dL) were selected from among the developmentally disabled residents of two California State Hospitals. These subjects were studied in order to identify the lead sources to which they were exposed and to abate the major ones. Three major lead sources were found in the state hospitals: wall and furniture paints (100–45,400 μg Pb/g paint); surface soil (33–570 μg Pb/g soil); magazine and wrapping paper (10–2600 μg Pb/g paper). In many cases an educational format was presented to all involved staff. The results have indicated a trend towards lower lead intake by the lead-burdened cases. In one of the two hospitals a “lead-free unit” had been established. All the lead-burdened cases were transferred to this unit in August 1981. A few months later the blood lead levels of all the cases dropped below 30 μg/dL. Initial epidemiological monitoring indicated where there were preventable hazards, which abatement efforts succeeded in reducing. Further monitoring of such problems is indicated in this and other developmentally-disabled populations.

Blood lead levels among high-risk children, Detroit, Michigan.

Since 1972, a federally funded lead screening program has been operational in Detroit, Michigan. Blood lead screening data (27,430 initial tests on Black children less than or equal to 6 years) were assigned by census tract of child's residence to one of the 15 socioeconomically similar areas in geographic proximity to one another. Higher blood lead levels were associated with lower education, lower income, and increased proportion of single parent families. This emphasizes the need to continue screening efforts in lower socioeconomic areas with older housing.

The identification and elimination of a potential lead hazard in an urban park.

During development of a park in Oakland, California, a potential public helath hazard due to lead in the soil (approximately 1,000 to 100,000 ppm) was identified through cooperative sampling and analysis efforts of the staffs at the county and state health departments. Analysis of samples collected at various locations and depths in the park, coupled with a three-dimensional model of the lead values obtained, indicated steps necessary to eliminate the hazard. The county undertook the abatement program, and with the elimination of the health hazard, the park development has been completed. Concomitant blood lead screening of neighborhood children failed to establish the park as a source of elevated lead in any of the children tested.