| Elevated Blood Lead Concentrations and Vitamin D Deficiency in Winter and Summer in Young Urban Children Francis W. Kemp,1 Prasad V.S.V. Neti,2 Roger W. Howell,2 Peter Wenger,1 Donald B. Louria,1 and John D. Bogden1 1Department of Preventive Medicine and Community Health, and 2Department of Radiology, University of Medicine and Dentistry of New Jersey–New Jersey Medical School, Newark, New Jersey, USA Abstract
Background: It is widely recognized that blood lead concentrations are higher in the summer than in winter. Although the effects of some environmental factors such as lead in dust on this phenomenon have been studied, relationships to sunlight-induced vitamin D synthesis have not been adequately investigated. Vitamin D status is influenced by the diet, sunlight exposure, age, skin pigmentation, and other factors, and may modify gastrointestinal lead absorption or release of lead stored in bones into the bloodstream. Objective and Methods: We collected paired blood samples from 142 young, urban African-American and Hispanic children in the winter and summer to study the seasonal increase in blood lead and its relationships to vitamin D nutrition, age, and race. Results: A winter/summer (W/S) increase in blood lead concentrations of 32.4% was found for children 1–3 years of age. There was a smaller W/S increase of 13.0% in children 4–8 years of age. None of the 51 Hispanic children had an elevated blood lead concentration (≥ 10 µg/dL) during the winter, and only one had an elevated summertime concentration. In contrast, elevated blood lead concentrations were frequent in the 91 African-American children, especially those 1–3 years of age. For the latter, the percentage with elevated blood lead levels increased from 12.2% in winter to 22.5% in summer. A 1.2% W/S increase in serum 25-hydroxy-vitamin D (serum 25-OH-D) concentrations was found for children 1–3 years of age. However, in children 4–8 years of age the W/S increase in serum 25-OH-D was much larger—33.6%. The percentages of children with low (< 16 µg/L) serum 25-OH-D concentrations were 12.0% in winter and 0.7% in summer and were consistently greater in African-American than in Hispanic children. The seasonal increases in blood lead and serum 25-OH-D in children 4–8 years of age were significantly associated. Conclusion: The higher summertime serum 25-OH-D concentrations for the 4- to 8-year-old children are likely caused by increased sunlight-induced vitamin D synthesis and may contribute to the seasonal increase in blood lead. Age and race are key factors that affect blood lead and vitamin D nutrition, as well as their interactions, in young urban children. Key words: African-American, blood, children, Hispanic, lead, summer, vitamin D, winter. Environ Health Perspect 115:630–635 (2007) . doi:10.1289/ehp.9389 available via http://dx.doi.org/ [Online 18 December 2006]
Address correspondence to J.D. Bogden, Department of Preventive Medicine and Community Health, Medical Sciences Building, Room F506, UMDNJ-New Jersey Medical School, 185 South Orange Ave., Newark, NJ 07103-2714 USA. Telephone: (973) 972-5432. Fax: (973) 972-7625. E-mail: bogden@umdnj.edu We appreciate the contribution of Y. Berry, a pediatric phlebotomist who collected the venous blood samples of all participating children. We are indebted to V. Jacobs-Andrews, director of the Women, Infants, and Children site at which all study subjects were enrolled, who arranged for our use of this facility. This research was supported by the UMDNJ Institute for Elimination of Health Disparities and the Healthcare Foundation of New Jersey. The authors declare they have no competing financial interests. Received 31 May 2006 ; accepted 18 December 2006.
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