David K. Parkinson

Assessment of Neuropsychological Dysfunction in the Workplace: Normative Data from the Pittsburgh Occupational Exposures Test Battery

Neuropsychologists are being increasingly called upon to assess the neurobehavioral status of adults who have been exposed to toxic chemicals or heavy metals in the workplace. Unfortunately, the evaluation of blue-collar workers has been hampered by the absence of a brief yet comprehensive battery of sensitive neuropsychological tests that have been administered to a large cohort of demographically similar adults with no prior history of occupational exposure. In this paper we describe the development of the Pittsburgh Occupational Exposures Test Battery. We detail the procedures used to collect appropriate age-scaled norms from 182 blue-collar males, and delineate the factor structure of the test battery. We also examine the interrelationships among test scores and certain demographic variables, and discuss the epidemiologic and clinical relevance of these data.

Effects of occupational stress on the physical and psychological health of women in a microelectronics plant

Physical and psychological effects of occupational stress were examined in a sample of 552 female blue collar employees of a microelectronics facility. After controlling for demographic and biological risk factors, non-work life events, and solvent exposure, job-related conflict was associated with depressive symptomatology, severe headaches, lightheadedness weakness/fatigue, rashes, and presence of multiple symptoms. Job demands were only associated with multiple symptoms. Solvent exposure did not interact with either of the job stress measures synergistically to increase symptom reports. Although the main effects of social support, when present, were in the direction of reducing symptomatology, the interactive effects of social support and stress on health were inconsistent and dependent on the source of support.

Low Level Lead Exposure and Neuropsychological Functioning in Blue Collar Males

To examine the interrelationships between normal aging, occupational lead exposure, and cognitive functioning, a comprehensive battery of neuropsychological tests was administered to 288 randomly-selected lead-exposed workers and 181 demographically-similar nonexposed controls. Contrary to previous reports, those workers with current blood-lead levels in the low to moderate range (less than 50 micrograms/dl) were found to perform as well as controls on measures of learning, memory, attention, visuospatial ability, and general intelligence. They differed from controls only on one measure of psychomotor speed and manual dexterity, the Grooved Pegboard Test, and these between-group differences were restricted to the older lead workers. It is likely that these results are secondary to lead-mediated neuromuscular damage. There is little support for the view that older adults with current blood lead levels in the low to moderate range are at risk for developing significant CNS dysfunction, even though they may have had a past history of excessively high blood lead levels.

Effects of Elevated Lead and Cadmium Burdens on Renal Function and Calcium Metabolism

To assess the pathophysiologic significance of increased body burdens of lead and cadmium, detailed renal function studies and evaluation of calcium, phosphorus, and vitamin D metabolism were carried out in 38 industrial workers exposed to lead and cadmium for 11 to 37 yr. Body burden of lead, as assessed by x-ray fluorescence measurement of tibia lead content, was elevated in 58% of the men and, when assessed by excretion of lead after Ca-EDTA infusion, was elevated in 36%. Liver or kidney cadmium burden, as assessed by neutron activation analysis, was elevated in 31%. Creatinine clearance was normal in all workers. One worker was hyperuricemic and two were proteinuric; three had increased beta 2 microglobulin excretion and one had diminished urinary acidifying ability. Maximal urinary concentrating ability was abnormal in a significant fraction, i.e., 52% of the men. Individuals with a high lead burden had a slight decrease in mean serum phosphorus but no accompanying phosphaturia. There was no abnormality of serum calcium. Twenty-two percent of subjects were hypercalciuric and two had low vitamin D levels, but these abnormalities bore no relation to heavy metal burden. In this carefully characterized group of men with chronic lead and calcium exposure, definite, if subclinical, effects on renal function and serum phosphorus but not calcium or vitamin D metabolism were demonstrable.

Agreement among Feighner, RDC and DSM III criteria for alcoholism.

Three sets of diagnostic criteria for alcoholism, Feighner criteria, Research Diagnostic Criteria (RDC), and DSM III criteria, were examined to determine the concordance among them. The alcohol section of the Diagnostic Interview Schedule (DIS), which provides information allowing for diagnoses by all three sets of criteria, was administered to 484 blue collar workers. Overall, there was substantial agreement among the diagnostic systems, with 86% of the men receiving the same diagnosis by all three systems. However, more detailed analyses indicated that approximately one quarter of those receiving a diagnosis of alcohol abuse or alcohol dependence according to DSM III were not diagnosed as alcoholic by Feighner criteria. It was suggested that this discrepancy was due to DSM III criteria (as represented in the DIS) diagnosing heavy drinkers with no attendant problems as alcoholic.