Academic journal article Environmental Health Perspectives

A Framework for Widespread Replication of a Highly Spatially Resolved Childhood Lead Exposure Risk Model

Academic journal article Environmental Health Perspectives

A Framework for Widespread Replication of a Highly Spatially Resolved Childhood Lead Exposure Risk Model

Article excerpt

BACKGROUND: Preventive approaches to childhood lead poisoning are critical for addressing this longstanding environmental health concern. Moreover, increasing evidence of cognitive effects of blood lead levels < 10 [micro]g/dL highlights the need for improved exposure prevention interventions.

OBJECTIVES: Geographic information system-based childhood lead exposure risk models, especially if executed at highly resolved spatial scales, can help identify children most at risk of lead exposure, as well as prioritize and direct housing and health-protective intervention programs. However, developing highly resolved spatial data requires labor- and time-intensive geocoding and analytical processes. In this study we evaluated the benefit of increased effort spent geocoding in terms of improved performance of lead exposure risk models.

METHODS: We constructed three childhood lead exposure risk models based on established methods but using different levels of geocoded data from blood lead surveillance, county tax assessors, and the 2000 U.S. Census for 18 counties in North Carolina. We used the results to predict lead exposure risk levels mapped at the individual tax parcel unit.

RESULTS: The models performed well enough to identify high-risk areas for targeted intervention, even with a relatively low level of effort on geocoding.

CONCLUSIONS: This study demonstrates the feasibility of widespread replication of highly spatially resolved childhood lead exposure risk models. The models guide resource-constrained local health and housing departments and community-based organizations on how best to expend their efforts in preventing and mitigating lead exposure risk in their communities.

KEY WORDS: children's health, environmental justice, exposure risk prevention, geocoding, GIS (geographic information systems), lead. Environ Health Perspect 116:1735-1739 (2008). doi:10.1289/ehp.11540 available via http://dx.doi.org/ [Online 14 August 2008]

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Although much progress has been made, childhood lead poisoning remains a critical environmental health and justice concern. Lead causes irreversible, asymptomatic effects at levels far below those previously considered safe. The 2003-2004 National Health and Nutrition Examination Survey (NHANES) survey data reveal blood lead levels (BLLs) at or above the Centers for Disease Control and Prevention (CDC) blood lead action level of 10 [micro]g/dL in 2.3% of 1- to 5-year-olds in the United States, with children tested having an overall geometric mean BLL of 2.1 [micro]g/dL (National Center for Health Statistics 2006). These data indicate that > 500,000 children < 6 years of age experience elevated BLLs (EBLLs) at or above the CDC blood lead action level of 10 [micro]g/dL (U.S. Census Bureau 2002).

Research suggests that significant adverse health effects occur at BLLs below the current CDC action level. Learning and behavioral deficits may occur even at BLLs < 5 [micro]g/dL (Canfield et al. 2003; Chiodo et al. 2004; Lanphear et al. 2000; Miranda et al. 2007; Schnaas et al. 2006). Meta-analysis and reviews suggest that there is no threshold effect level, so any level of exposure is potentially detrimental (Gatsonis and Needleman 1992; Lanphear et al. 2005; Schwartz 1993, 1994). Thus, the number of children negatively affected by low-level lead exposure is likely much higher than estimates based upon the CDC action level. From a public health perspective, it is critical to get children who are at risk screened for lead in a timely manner and to intervene to rehabilitate the portions of the housing stock that pose the greatest risk of lead exposure.

Geographic information systems (GIS) hold particular promise for addressing the risks of childhood lead exposure. Wartenberg (1991) proposed a framework within which each type of screening approach--from health care provider and city clinic to door-to-door and finally to GIS-directed or informed screening--increases the case-finding rate. …

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