Environmental lead exposure: a public health problem of global dimensions.
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Lead is the most abundant of the heavy metals in the Earth's crust. It has been used since prehistoric times, and has become widely distributed and mobilized in the environment. Exposure to and uptake of this non-essential element have consequently increased. Both occupational and environmental exposures to lead remain a serious problem in many developing and industrializing countries, as well as in some developed countries. In most developed countries, however, introduction of lead into the human environment has decreased in recent years, largely due to public health campaigns and a decline in its commercial usage, particularly in petrol. Acute lead poisoning has become rare in such countries, but chronic exposure to low levels of the metal is still a public health issue, especially among some minorities and socioeconomically disadvantaged groups. In developing countries, awareness of the public health impact of exposure to lead is growing but relatively few of these countries have introduced policies and regulations for significantly combating the problem. This article reviews the nature and importance of environmental exposure to lead in developing and developed countries, outlining past actions, and indicating requirements for future policy responses and interventions. (+info)
Lead loading of urban streets by motor vehicle wheel weights.
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This study documents that lead weights, which are used to balance motor vehicle wheels, are lost and deposited in urban streets, that they accumulate along the outer curb, and that they are rapidly abraded and ground into tiny pieces by vehicle traffic. The lead is so soft that half the lead deposited in the street is no longer visible after little more than 1 week. This lead loading of urban streets by motor vehicle wheel weights is continuous, significant, and widespread, and is potentially a major source of human lead exposure because the lead is concentrated along the outer curb where pedestrians are likely to step. Lead deposition at one intersection in Albuquerque, New Mexico, ranged from 50 to 70 kg/km/year (almost 11 g/ft(2)/year along the outer curb), a mass loading rate that, if accumulated for a year, would exceed federal lead hazard guidelines more than 10,000 times. Lead loading of major Albuquerque thoroughfares is estimated to be 3,730 kg/year. Wheel weight lead may be dispersed as fugitive dust, flushed periodically by storm water into nearby waterways and aquatic ecosystems, or may adhere to the shoes of pedestrians or the feet of pets, where it can be tracked into the home. I propose that lead from wheel weights contributes to the lead burden of urban populations. (+info)
Elevated blood lead levels among adults in Massachusetts, 1991-1995.
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OBJECTIVE: Lead poisoning, the oldest recognized occupational disease, remains a danger for children and adults. Data collected for 664 cases reported to the Massachusetts Occupational Lead Registry in 1991-1995 were summarized in a 1998 state report. Here, the authors present some of the key findings from that report for a wider audience. METHODS: The authors summarize key findings of the 1998 state report. FINDINGS: Construction workers, in particular licensed deleaders and house painters, accounted for almost 70% of occupational cases involving blood lead levels > or = 40 micrograms of lead per deciliter (mcg/dl) of blood. Among 100 workers with the highest blood lead levels (> or = 60 mcg/dl), 29% were house painters. Hispanic workers were over-represented in the Registry. A small proportion of cases were non-occupational, typically associated with recreational use of firing ranges or do-it-yourself home renovations. CONCLUSION: Lead poisoning is a preventable disease, yet these data indicate that additional prevention efforts are warranted. (+info)
A case of lead poisoning due to snooker chalk.
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A 3 year, 9 month old child with pica presented with a blood lead concentration of 1.74 micromol/l (360 microg/l). The source of poisoning was snooker chalk (lead content 7200 microg/g). She was treated with intravenous calcium disodium edetate chelation. Thirty months later her blood lead was 0.39 micromol/l (80 microg/l). This case illustrates the need to be vigilant for more unusual causes of lead poisoning in the home. (+info)
Recommendations for blood lead screening of young children enrolled in medicaid: targeting a group at high risk.
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Children aged 1-5 years enrolled in Medicaid are at increased risk for having elevated blood lead levels (BLLs). According to estimates from the National Health and Nutrition Examination Survey (NHANES) (1991-1994), Medicaid enrollees accounted for 83% of U.S. children aged 1-5 years who had BLLs > or = 20 microg/dL. Despite longstanding requirements for blood lead screening in the Medicaid program, an estimated 81% of young children enrolled in Medicaid had not been screened with a blood lead test. As a result, most children with elevated BLLs are not identified and, therefore, do not receive appropriate treatment or environmental intervention. To ensure delivery of blood lead screening and follow-up services for young children enrolled in Medicaid, the Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP) recommends specific steps for health-care providers and states. Health-care providers and health plans should provide blood lead screening and diagnostic and treatment services for children enrolled in Medicaid, consistent with federal law, and refer children with elevated BLLs for environmental and public health follow-up services. States should change policies and programs to ensure that young children enrolled in Medicaid receive the screening and follow-up services to which they are legally entitled. Toward this end, states should a) ensure that their own Medicaid policies comply with federal requirements, b) support health-care providers and health plans in delivering screening and follow-up services, and c) ensure that children identified with elevated BLLs receive essential, yet often overlooked, environmental follow-up care. States should also monitor screening performance and BLLs among young children enrolled in Medicaid. Finally, states should implement innovative blood lead screening strategies in areas where conventional screening services have been insufficient. This report provides recommendations for improved screening strategies and relevant background information for health-care providers, state health officials, and other persons interested in improving the delivery of lead-related services to young children served by Medicaid. (+info)
Bone lead and blood lead levels in relation to baseline blood pressure and the prospective development of hypertension: the Normative Aging Study.
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Between 1991 and 1997, the authors studied 833 participants of the Normative Aging Study in a substudy of bone lead levels (measured by K-shell x-ray fluorescence), blood lead levels, and hypertension. Among these subjects, 337 were classified as normotensive, and 182 and 314 were classified as having borderline and definite hypertension, respectively, at baseline. These bone and blood lead levels were typical of those of community-exposed men. Among the 519 subjects with no history of definite hypertension at baseline, cross-sectional analyses revealed positive associations between systolic blood pressure and bone lead levels. Of the 474 subjects who were free from definite hypertension at baseline and had follow-up data, 74 new cases of definite hypertension were reported. Baseline bone lead levels were positively associated with incidence of hypertension. In proportional hazards models that controlled for age, age squared, body mass index, and family history of hypertension, an increase in patella (trabecular) lead from the midpoint of the lowest quintile to that of the highest quintile was associated with a rate ratio of definite hypertension of 1.71 (95% confidence interval: 1.08, 2.70). No association was found with blood lead level. These results support the hypothesis that cumulative exposure to lead, even at low levels sustained by the general population, may increase the risk of hypertension. (+info)
Micro-scale blood lead determinations in screening: evaluation of factors affecting results.
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The Delves micro-scale technique for blood lead analysis is an accurate method for screening capillary blood specimens, obtained by fingerstick, for lead intoxication. Results are affected by the age of cup, loop, and hollow-cathode tube and by the spatial relationship between optical tube and cup. Because the glass in many commercially available capillary tubes (used in specimen collection) contains lead and cannot be decontaminated, a lead-free glass tube must be used. A solution of citric acid in ethanol (20 g/liter) effectively cleanses the puncture site. A double-blind study of 207 specimens gave a mean value of 276.6 plus or minus 105.8 mug/liter (1SD) for the micro-scale method vs. 273.2 plus or minus 99.0 for a macro-scale method. The mean coefficent of variation for the micro-scale method was 5.75 percent plus or minus 1.9 (SD). We conclude that values of 480 mug/liter or below are not "toxic" (i.e., are significantly less than 600 mug/liter, the value at which therapy is begun). The method is shown to be satisfactory as a screening procedure and for confirming lead analyses done by other methods. (+info)
Use of geographic information system technology to aid Health Department decision making about childhood lead poisoning prevention activities.
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The Centers for Disease Control and Prevention recommend that local public health agencies use local data to identify children at risk for lead exposure to ensure that they receive preventive services. The objective of this study was to demonstrate the usefulness of a geographic information system (GIS) in identifying children at risk for lead exposure. We conducted a descriptive study, using GIS technology, of the blood lead (BPb) levels and residential location of at-risk children screened for lead exposure. "At-risk children" were defined as those children living in housing built before 1950 or in an area with a high proportion of older housing. The study was conducted in Jefferson County, Kentucky, USA. Participants were the cohort of children born in 1995 and screened from 1996 through 1997, and children younger than age 7 years who were screened from 1994 through 1998. Outcome measures were the BPb level and residential location (address or target zone) of at-risk children screened from 1996 through 1997, and the number and location of homes where more than one child had been poisoned by lead from 1994 through 1998. The proportion of children screened who live within zones targeted for universal screening varied from 48% to 53%, while only 50% of the at-risk children in the entire county were screened. Between 1994 and 1998, 79 homes housed 35% of the 524 children with lead poisoning. These housing units were prioritized for lead-hazard remediation. Significant numbers of at-risk children throughout the county were not being tested for lead exposure, even in prioritized areas. GIS can be very useful to health departments in planning lead exposure screening strategies and measuring program performance. (+info)