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Occupational lead exposure: risk to the aging worker.

Morrow-LA; Needleman-H; Kirisci-L; Sandstrom-D
NIOSH 2005 Jan; :1-5
This study investigated neuropsychiatric changes associated with lead exposure. Persons with past and current exposure to lead were compared to a demographically similar non-exposed control group. That is, between 1981 and 1984, lead-exposed and non-exposed workers were evaluated as part of an epidemiological study of lead conducted at the University of Pittsburgh. Lead-exposed workers were members of District 10, United Steel Workers of America, and worked at three industrial plants in Eastern Pennsylvania {approximately 200 miles from Pittsburgh) that manufactured lead batteries for automobiles and motorcycles {one of the three plants is still in operation). At the initial testing, subjects were randomly selected from company lists: the lead-exposed workers had a mean age of 35 {range 21-60) and blood lead levels averaged 40,ug/dl, with peak blood levels around 90,ug/dl. Demographically similar non-exposed blue-collar workers were also seen for the initial study {mean age = 35). For the current study we attempted to recruit as many subjects as possible who were initially tested approximately 20 years ago and to repeat the neuropsychological test battery. In addition, information was collected on current and past psychiatric history, and current blood lead levels {BLL) were obtained. Finally, bone concentration of lead was determined with x-ray fluorescence {XRF) -a procedure that was not available 20 years ago. We were able to contact 169 of the subjects who had been evaluated 20 years earlier. We originally estimated we would be able to locate 212 subjects. Of the 169 subjects who were located, 141 (83.4%) traveled to Pittsburgh (more than a three hour drive with an overnight stay) for the assessment. Of the 141 subjects who completed the entire testing, 89 were lead-exposed workers and 52 were controls. We saw our final subject two months ago. At this date, we have begun preliminary analysis of the data. Because prior research suggested that mobilization of lead stores from bone increases with advancing age, we have assessed the relationship between bone lead and blood lead level for subjects across age groups. At the time of the current assessment the average blood lead level was 10.93 ug/dL and tibia bone lead concentrations ranged from -12.58 to 223.33. Correlations between blood lead and bone lead were highest in the middle and oldest age bands (.49 and. 75, respectively). Hierarchical regression analyses demonstrated that the interaction of bone lead and age significantly predicted current blood lead levels. The results support the hypothesis that lead stored in bone is a significant source of blood lead later in life and suggest that older workers with past occupational exposure may face a particular risk for recirculation of lead in blood with advancing age. Preliminary analyses are also currently being done to examine the change in neuropsychological function. Lead workers have poorer scores on the majority of neuropsychological tests. In addition, a comparison between the initial neuropsychological testing and the current testing shows that bone lead levels are related to neuropsychological decline. That is, workers with higher levels of bone lead show significantly more impairment on measures of problem solving, spatial reasoning and overall cognitive function, even after controlling for confounding variables (e.g., education, medical risk factors) and baseline neuropsychological performance. These findings suggest that lead exposure may pose a significant risk factor for cognitive decline in later years.
Blood-analysis; Blood-tests; Heavy-metals; Heavy-metal-poisoning; Lead-compounds; Battery-manufacturing-industry; Metal-compounds; Metals; Metal-poisoning; Demographic-characteristics; Statistical-analysis; Epidemiology; Psychological-effects; Age-factors
University of Pittsburgh School of Medicine, 3811 O'Hara Street, Pittsburgh, PA 15231
Publication Date
Document Type
Final Grant Report
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Fiscal Year
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NIOSH Division
Priority Area
Work Environment and Workforce: Special Populations
Source Name
National Institute for Occupational Safety and Health
Performing Organization
University of Pittsburgh, Pittsburgh, Pennsylvania