title: A multi-level model of blood lead as a function of air lead.
abstract: National and local declines in lead (Pb) in blood (PbB) over the past several years coincide with the decline in ambient air Pb (PbA) concentrations. The objective of this work is to evaluate how the relationship between PbB levels and PbA levels has changed following the phase out of leaded gasoline and tightened controls on industrial Pb emissions over the past 30 years among a national population sample. Participant-level data from the National Health and Nutrition Examination Survey (NHANES) were employed for two time periods (1988-1994 and 1999-2008), and the model was corrected for housing, demographic, socioeconomic, and other covariates present in NHANES. NHANES data for PbB and covariates were merged with PbA data from the U.S. Environmental Protection Agency. Linear mixed effects models (LMEs) were run to assess the relationship of PbB with PbA; sample weights were omitted, given biases encountered with the use of sample weights in LMEs. The 1988-1994 age-stratified results found that ln(PbB) was statistically significantly associated with ln(PbA) for all age groups. The consistent influence of PbA on PbB across age groups for the years 1988-1994 suggests a ubiquitous exposure unrelated to age of the sample population. The comparison of effect estimates for ln(PbA) shows a statistically significant effect estimate and ANOVA results for ln(PbB) for the 6- to 11-year and 12- to 19-year age groups during 1999-2008. The more recent finding suggests that PbA has less consistent influence on PbB compared with other factors.
authors.affiliation: National Center for Environmental Assessment, U.S. Environmental Protection Agency, 109 TW Alexander Drive, B243-01, Research Triangle Park, NC 27711, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Richmond-Bryant
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Meng
authors.forename: J Allen
authors.initials: JA
authors.lastname: Davis
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cohen
authors.forename: David
authors.initials: D
authors.lastname: Svendsgaard
authors.forename: James S
authors.initials: JS
authors.lastname: Brown
authors.forename: Lauren
authors.initials: L
authors.lastname: Tuttle
authors.forename: Heidi
authors.initials: H
authors.lastname: Hubbard
authors.forename: Joann
authors.initials: J
authors.lastname: Rice
authors.forename: Ellen
authors.initials: E
authors.lastname: Kirrane
authors.forename: Lisa
authors.initials: L
authors.lastname: Vinikoor-Imler
authors.forename: Dennis
authors.initials: D
authors.lastname: Kotchmar
authors.forename: Erin
authors.initials: E
authors.lastname: Hines
authors.forename: Mary
authors.initials: M
authors.lastname: Ross
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000393:Air Pollutants / Q000032:analysis* / Q000266:history; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood*; D002648:Child; D003710:Demography; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data*; D040362:Geographic Information Systems; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D007854:Lead / Q000032:analysis* / Q000097:blood*; D016014:Linear Models; D008962:Models, Theoretical; D009749:Nutrition Surveys; D012959:Socioeconomic Factors
chemical_list: D000393:Air Pollutants; D015415:Biomarkers; D007854:Lead
keywords: Air lead; Air pollution; Biomarkers of exposure; Blood lead; Children; NHANES