title: Occupational lead exposure and longitudinal decline in neurobehavioral test scores.
abstract: BACKGROUND
  No previous longitudinal studies have compared and contrasted associations of blood lead and tibia lead with declines in cognitive function over the course of time in a large sample of subjects with current and past occupational exposure to inorganic lead.
  
  
  METHODS
  From 1997 through 2001, we conducted a longitudinal study of 803 current and former lead workers in South Korea to evaluate effects on the central and peripheral nervous systems. Three study visits occurred during a mean follow-up duration of 2.20 years. Neurobehavioral test scores, peripheral nervous system function, and blood lead were measured at each of the 3 study visits, whereas tibia lead was measured by x-ray fluorescence at the first and second visits. We limited our analysis to the 576 lead workers who completed testing at all 3 visits. We performed regression analyses using generalized estimating equations.
  
  
  RESULTS
  There were consistent associations of blood lead with test scores at baseline and of tibia lead with declines in test scores over the next year, mainly in executive abilities, manual dexterity, and peripheral vibration threshold.
  
  
  CONCLUSIONS
  The results support the inference that occupational lead exposure can cause declines in cognitive function over the course of time. Lead likely has an acute effect on neurobehavioral test scores as a function of recent dose and a longer-term (possibly progressive) effect on cognitive decline as a function of cumulative dose.
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Schwartz
authors.forename: Byung-Kook
authors.initials: BK
authors.lastname: Lee
authors.forename: Karen
authors.initials: K
authors.lastname: Bandeen-Roche
authors.forename: Walter
authors.initials: W
authors.lastname: Stewart
authors.forename: Karen
authors.initials: K
authors.lastname: Bolla
authors.forename: Jonathan
authors.initials: J
authors.lastname: Links
authors.forename: Virginia
authors.initials: V
authors.lastname: Weaver
authors.forename: Andrew
authors.initials: A
authors.lastname: Todd
mesh_terms: D000328:Adult; D000465:Algorithms; D003430:Cross-Sectional Studies; D006801:Humans; D007723:Korea / Q000453:epidemiology; D007854:Lead / Q000032:analysis / Q000097:blood; D020265:Lead Poisoning, Nervous System, Adult / Q000453:epidemiology* / Q000209:etiology; D008137:Longitudinal Studies; D008669:Metallurgy; D008875:Middle Aged; D008962:Models, Theoretical; D016273:Occupational Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D012044:Regression Analysis; D013977:Tibia / Q000378:metabolism; D013997:Time Factors
chemical_list: D007854:Lead