| Cumulative Lead Dose and Cognitive Function in Adults: A Review of Studies That Measured Both Blood Lead and Bone Lead Regina A. Shih,1 Howard Hu,2,3 Marc G. Weisskopf,2,3 and Brian S. Schwartz4,5 1Division of Epidemiology, Statistics, and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland, USA; 2Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 3Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; 4Departments of Environmental Health Sciences and Epidemiology, Johns Hopkins Bloomberg School of Public Health, and 5Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA Abstract
Objective: We review empirical evidence for the relations of recent and cumulative lead dose with cognitive function in adults. Data Sources: A systematic search of electronic databases resulted in 21 environmental and occupational studies from 1996 to 2006 that examined and compared associations of recent (in blood) and cumulative (in bone) lead doses with neurobehavioral outcomes. Data Extraction: Data were abstracted after consideration of exclusion criteria and quality assessment, and then compiled into summary tables. Conclusions: At exposure levels encountered after environmental exposure, associations with biomarkers of cumulative dose (mainly lead in tibia) were stronger and more consistent than associations with blood lead levels. Similarly, in studies of former workers with past occupational lead exposure, associations were also stronger and more consistent with cumulative dose than with recent dose (in blood) . In contrast, studies of currently exposed workers generally found associations that were more apparent with blood lead levels ; we speculate that the acute effects of high, recent dose may mask the chronic effects of cumulative dose. There is moderate evidence for an association between psychiatric symptoms and lead dose but only at high levels of current occupational lead exposure or with cumulative dose in environmentally exposed adults. Key words: adults, blood, bone, cognitive function, lead, neurobehavior. Environ Health Perspect 115:483–492 (2007) . doi:10.1289/ehp.9786 available via http://dx.doi.org/ [Online 22 December 2006]
This article is part of the mini-monograph "Lead Exposure and Health Effects in Adults: Evidence, Management, and Implications for Policy." Address correspondence to B.S. Schwartz, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe St., Rm. W7041, Baltimore, Maryland 21205 USA. Telephone: (410) 955-4130. Fax: (410) 955-1811. E-mail: bschwart@jhsph.edu This work was supported in part by National Institute of Aging R01-AG19604 and R01-AG10785 ; National Institute of Environmental Health Sciences R01-ES07198, R01-ES05257, R01-ES10798, P42-ES05947, P30-ES00002, and K01-ES012653 ; and intramural funds from NICHD. The authors declare they have no competing financial interests. Received 3 October 2006 ; accepted 15 November 2006.
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