title: Neurobehavioral function and tibial and chelatable lead levels in 543 former organolead workers.
abstract: OBJECTIVE
  To evaluate the associations between tibial lead, dimercaptosuccinic acid (DMSA)-chelatable lead, and neurobehavioral function in former organolead manufacturing workers with past exposure to organic and inorganic lead.
  
  
  METHODS
  Data were collected from 543 subjects with a mean age of 58 years and an average of 17.8 years since last lead exposure. Years since last exposure to lead was used to estimate tibial lead levels in the year of last occupational lead exposure, termed "peak tibial lead." Current tibial lead levels, measured by x-ray fluorescence, were extrapolated back using a clearance half-time of lead in tibia of 27 years, assuming first-order clearance from tibia.
  
  
  RESULTS
  Peak tibial lead levels ranged from -2.2 to 105.9 microg Pb/g bone mineral, and DMSA-chelatable lead levels were between 1.2 and 136 microg. After adjustment for confounding variables, peak tibial lead was a significant negative predictor of performance on the Wechsler Adult Intelligence Scale-Revised vocabulary subtest (p = 0.02), serial digit learning test (p = 0.04), Rey Auditory-Verbal Learning Test (immediate recall and recognition, p = 0.03 for each), Trail Making Test B (p = 0.03), finger tapping (dominant hand [p = 0.02] and nondominant hand [p < 0.01]), Purdue pegboard (dominant hand, nondominant hand, both hands, and assembly, p < 0.01 for each), and Stroop Test (p < 0.01). Moreover, with one exception, average neurobehavioral test scores were poorer at higher peak tibial lead levels. DMSA-chelatable lead was only significantly associated with choice reaction time (p = 0.01).
  
  
  CONCLUSIONS
  Peak tibial lead was consistently associated with poorer neurobehavioral test scores, particularly in the domains of manual dexterity, executive ability, verbal intelligence, and verbal memory.
authors.affiliation: Department of Epidemiology, Johns Hopkins School of Hygiene and Public Health, Baltimore, MD 21205, USA.
authors.forename: W F
authors.initials: WF
authors.lastname: Stewart
authors.forename: B S
authors.initials: BS
authors.lastname: Schwartz
authors.forename: D
authors.initials: D
authors.lastname: Simon
authors.forename: K I
authors.initials: KI
authors.lastname: Bolla
authors.forename: A C
authors.initials: AC
authors.lastname: Todd
authors.forename: J
authors.initials: J
authors.lastname: Links
mesh_terms: D000328:Adult; D000368:Aged; D001519:Behavior / Q000187:drug effects*; D003625:Data Collection; D006801:Humans; D007854:Lead / Q000009:adverse effects / Q000032:analysis* / Q000097:blood; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D016273:Occupational Exposure / Q000032:analysis*; D009942:Organometallic Compounds / Q000009:adverse effects / Q000032:analysis* / Q000097:blood; D011446:Prospective Studies; D013977:Tibia / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D007854:Lead