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Blood Lead Levels Among Children in High-Risk Areas -- California, 1987-1990

In the United States, elevated blood lead levels (BLLs) are a major health risk for children; this risk is totally preventable (1). To better characterize lead poisoning among children at high risk for lead exposure in California, the California Department of Health Services (CDHS) conducted lead-screening surveys that measured lead levels in children's blood, household paint, and soil in three selected high-risk areas in northern, southern, and central California. This report summarizes the survey findings and describes CDHS's efforts to reduce lead exposure among children in California, especially among those in high-risk areas.

CDHS selected three areas for the surveys based on the likelihood that old housing in these areas contained lead paint (42%-72% of the housing in the survey areas was built before 1950): Oakland in Alameda County (1987); Wilmington and Compton in Los Angeles County (1988); and Sacramento in Sacramento County (1990). In the Oakland and Sacramento survey areas, CDHS attempted to enroll all households with children aged 12-59 months. In the two communities in Los Angeles County, a systematic sample of every fourth block was selected, and CDHS attempted to enroll all households with children aged 12-59 months in those sample blocks. The proportion of eligible households agreeing to participate in each area included 358 (71%) of 506 in Oakland, 350 (56%) of 621 in Wilmington/Compton, and 232 (47%) of 495 in Sacramento. Overall, these households included 973 families with 1397 children in the target age range (ages of children were equally distributed). *

In Oakland, initial blood lead testing was performed by collecting capillary blood samples from the children. To reduce the possibility of sample contamination caused by lead on children's hands, their hands were vigorously washed before the capillary sample was obtained; a confirmatory venous sample was obtained from 74% of the Oakland children with an initial capillary BLL greater than or equal to 15 ug/dL. In Wilmington/Compton and Sacramento, venous blood samples were collected from 96% of the participating children; capillary samples were collected from the other 4% of children surveyed.

In Oakland and Wilmington/Compton, household paint samples were collected only when peeling or chipping paint was observed; in Sacramento, paint samples were collected from surfaces regardless of condition. At each household, soil samples of the top inch of soil were collected from one to five locations (i.e., midsection of front, back, and side yards; directly beneath a rain drain; and near a building not attached to the house on the household property); soil lead level was defined as the geometric mean of all samples collected at the household. Paint lead levels reported were the maximum level found at a home. Lead content in blood and environmental samples was measured using graphite-furnace atomic-absorption spectrophotometry.

In these three areas, 40%-84% of children were Hispanic and members of families with reported annual family incomes of less than $15,000. BLLs of greater than or equal to 10 ug/dL ** were detected in 67% of children in Oakland, 32% in Wilmington/Compton, and 14% in Sacramento. BLLs greater than or equal to 20 ug/dL *** were detected in 5% of children in Oakland, 4% in Wilmington/Compton, and 1% in Sacramento.

Geometric mean lead levels in household paint were highest in Oakland and lowest in Wilmington/Compton (range for exterior paint: 3100-13,545 parts per million (ppm)) (Table 1). In all three areas, exterior surfaces were substantially higher in paint lead levels than were interior surfaces. However, lead levels for some interior paint samples exceeded 5000 ppm (37% in Oakland, 25% in Sacramento, and 13% in Wilmington/Compton). **** Soil lead levels were highest in Oakland where 46% of household soil lead levels exceeded 1000 ppm.

Reported by: M Haan, DrPH, L Zahler, MPH, M Athanasoulis, R Broadwin, Impact Assessment, Inc, LaJolla; J Mann, MPH, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency; LR Goldman, MD, P Sutton, MPH, R Schlag, MSc, R Mc Laughlin, MA, Environmental Epidemiology and Toxicology Program; P Flessel, PhD, G Guirguis, PhD, Air and Industrial Hygiene Laboratory, California Dept of Health Svcs. Lead Poisoning Prevention Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health and Injury Control, CDC.

Editorial Note

Editorial Note: Because recent research findings indicate that adverse health effects may occur among children with BLLs greater than or equal to 10 ug/dL, CDC guidelines recommend actions to reduce lead exposure in communities where such levels are prevalent (2). Before the CDHS assessment, the potential risk for childhood lead poisoning had not been widely recognized in California or other western states. However, the CDHS findings summarized in this report indicate a high prevalence of elevated BLLs among children in high-risk communities in California and are consistent with reports elsewhere (4). Although many children participating in these surveys had BLLs that exceeded the guidelines, the levels were too low to cause overt symptoms; thus, in the absence of the CDHS survey, the high prevalence of this problem in Oakland may not have been recognized.

Lead-based paint, the most common source of high-dose lead exposure for children (4), was present in a high proportion of the dwellings surveyed by CDHS. In the western U.S. census region, an estimated 80% of privately owned housing units built before 1980 contain some lead-based paint, and the prevalence and concentration of lead in paint is proportionate to the age of the housing units (5). In California, an estimated 560,000 children aged less than 6 years reside in housing units built before 1950 that probably contain high levels of lead in paint (4).

In addition to lead-based paint, there are at least three other important potential sources for lead exposure in California. First, lead-contaminated soil was common in the communities surveyed; in urban areas, such contamination may result from deteriorating exterior lead-based paint and/or from emissions from automobiles using leaded gasoline (2). Second, in California, seven secondary lead smelters may contribute to contamination of nearby soil. Third, in addition to environmental sources, the use of folk medicines (6) and pottery containing lead is prevalent among some minority groups and has caused severe cases of childhood lead poisoning.

In January 1992, the use of leaded gasoline was banned by law in California. In addition, CDHS is exploring other strategies to remove lead from consumer products and to identify and remove lead hazards from high-risk communities. The CDHS is implementing a comprehensive lead-poisoning prevention program that includes periodic blood lead testing for children aged less than 6 years; case management by local health agencies; laboratory-based reporting (2); and educational programs for local health departments, health-care providers, and the public. During 1992, CDHS has been preparing regulations for residential lead-paint abatement. CDHS also is implementing strategies to reduce occupational lead poisoning, prevent the use of lead-based folk medicines, and eliminate other sources of lead exposure.

References

  1. Public Health Service. Healthy people 2000: national health promotion and disease prevention objectives -- full report, with commentary. Washington, DC: US Department of Health and Human Services, Public Health Service, 1991; DHHS publication no. (PHS)91-50212.

  2. CDC. Preventing lead poisoning in young children: a statement by the Centers for Disease Control--October 1991. Atlanta: US Department of Health and Human Services, Public Health Service, 1991.

  3. Office of Public and Indian Housing. Lead-based paint: interim guidelines for hazard identification and abatement in public and Indian housing. Washington, DC: US Department of Housing and Urban Development, Office of Public and Indian Housing, 1990.

  4. Agency for Toxic Substances and Disease Registry. The nature and extent of lead poisoning in children in the United States: a report to Congress. Atlanta: US Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, 1988.

  5. US Department of Housing and Urban Development. Comprehensive and workable plan for the abatement of lead-based paint in privately owned housing: a report to Congress. Washington, DC: US Department of Housing and Urban Development, Office of Policy Development and Research, 1990.

  6. Los Angeles County Department of Health Services. Azarcon use in Los Angeles County. In: Public Health Letter. Los Angeles: Los Angeles County Department of Health Services, August 1982 (vol 4, no. 8).

    • In Los Angeles County, of 471 children surveyed, 272 were excluded because the blood collection tube lot used for their samples was later found to be contaminated with lead; the remaining 199 children included in the study had household environmental lead levels and demographic characteristics similar to those of the excluded children. Paint and soil lead levels are presented for all 350 households. ** Levels at which adverse health effects in children have been demonstrated (2). *** Levels high enough to require medical evaluation according to CDC guidelines (2). **** According to guidelines established by the U.S. Department of Housing and Urban Development (3), surfaces with paint lead levels of greater than or equal to 5000 ppm should be abated during comprehensive modernization activities.



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