| Blood Lead Level and Risk of Asthma Christine L.M. Joseph,1 Suzanne Havstad,1 Dennis R.
Ownby,2 Edward L. Peterson,1 Mary Maliarik,1 Michael
J. McCabe Jr.,3 Charles Barone,1 and Christine
Cole Johnson1 1Department of Biostatistics and Research Epidemiology, Henry Ford
Health System, Detroit, Michigan, USA; 2Allergy-Immunology
Section, Medical College of Georgia, Augusta, Georgia, USA; 3Department
of Environmental Medicine, University of Rochester School of Medicine, Rochester,
New York, USA Abstract
Asthma and lead poisoning are prevalent among urban children in the United States. Lead exposure may be associated with excessive production of immunoglobulin E, possibly increasing asthma risk and contributing to racial disparities. The objective of this study was to examine racial differences in the association of blood lead level (BLL) to risk of developing asthma. We established and followed a cohort prospectively to determine asthma onset, using patient encounters and drug claims obtained from hospital databases. Participants were managed care enrollees with BLL measured and documented at 1-3 years of age. We used multiple variable analysis techniques to determine the relationship of BLL to period prevalent and incident asthma. Of the 4,634 children screened for lead from 1995 through 1998, 69.5% were African American, 50.5% were male, and mean age was 1.2 years. Among African Americans, BLL ≥ 5 and BLL ≥ 10 µg/dL were not associated with asthma. The association of BLL ≥ 5 µg/dL with asthma among Caucasians was slightly elevated, but not significant [adjusted hazard ratio (adjHR) = 1.4 ; 95% confidence interval (CI) , 0.7-2.9 ; p = 0.40]. Despite the small number of Caucasians with high BLL, the adjHR increased to 2.7 (95% CI, 0.9-8.1 ; p = 0.09) when more stringent criteria for asthma were used. When compared with Caucasians with BLL < 5 µg/dL, African Americans were at a significantly increased risk of asthma regardless of BLL (adjHR = 1.4-3.0) . We conclude that an effect of BLL on risk of asthma for African Americans was not observed. These results demonstrate the need for further exploration of the complex interrelationships between race, asthma phenotype, genetic susceptibilities, and socioenvironmental exposures, including lead. Key words: asthma, atopy, environment, immunoglobulin E, incidence, lead poisoning, racial disparity. Environ Health Perspect 113: 900-904 (2005) . doi:10.1289/ehp.7453 doi:10.1289/ehp.7453 available via http://dx.doi.org/ [Online 3 March 2005]
Address correspondence to C.L.M. Joseph, Henry Ford Health System, Department of Biostatistics and Research Epidemiology, 1 Ford Pl., Suite 3E, Detroit, MI 48202 USA. Telephone: (313) 874-6366. Fax: (313) 874-6730. E-mail: cjoseph1@hfhs.org We acknowledge the valuable contributions of R. Rasmusson, K. Wells, and J. Zajechowski in the preparation of the manuscript. This research was funded by the National Heart, Lung, and Blood Institute (R03 HL67462) . The authors declare they have no competing financial interests. Received 27 July 2004 ; accepted 3 March 2005. The full version of this article is available for free in HTML or PDF formats. |
