Stuart L. Shalat

Risk factors for Alzheimer's disease A case‐control study

A case-control study was conducted to assess personal and family medical history and the appearance of Alzheimers disease. We compared 98 men with clinically diagnosed Alzheimers disease and 162 controls, matched by sex, year of birth, and town of residence. Family history of dementia and personal history of depression were more frequent in patients. The number of cigarettes smoked was geater in cases.

Liver Disease Associated with Occupational Exposure to the Solvent Dimethylformamide

STUDY OBJECTIVE to characterize an outbreak of liver disease among workers in a fabric coating factory; and to determine the outbreaks cause and natural history and strategies for clinical recognition, treatment, and prevention. DESIGN clinical-epidemiological investigation. SETTING academic medical center, Occupational Medicine Clinic, and worksite. PATIENTS fifty-eight of sixty-six workers participated in the study. All had standard liver function tests at least once. Forty-six workers completed a questionnaire; 27 had more extensive clinical evaluation for recognized liver abnormalities. RESULTS a plant-wide outbreak of liver disease was recognized after a new employee presented with signs and symptoms of hepatitis. Evaluation of the worksite showed that dimethylformamide, a widely used industrial solvent and known hepatotoxin, was being used to coat fabric in poorly ventilated areas without appropriate skin protection. No other major hepatotoxic exposure was identified. Overall, 36 of 58 (62%) workers tested had elevations of either aspartate aminotransferase (AST) or alanine aminotransferase (ALT) levels. Enzyme abnormalities occurred almost exclusively in production workers (35 of 46 were abnormal), whereas only 1 of 12 nonproduction workers showed any elevations in enzyme levels (P less than 0.0001). Serologic tests excluded known infectious causes of hepatitis in all but 2 workers and changes characteristic of toxic liver injury were confirmed by histologic examinations of biopsy specimens from 4 workers. The ratio of AST to ALT levels was one or less in all but 1 worker. After modification of work practices and removal of workers most severely affected from exposure, improvement in liver enzyme abnormalities and symptoms in most patients were seen, although some patients showed persistent elevations of enzyme levels. CONCLUSIONS an outbreak of toxic liver disease has been associated with exposure to dimethylformamide in the workplace. The diagnosis of toxic liver disease was established by the clinical histories, negative viral serologies, an enzyme pattern of ALT levels being greater than AST levels, epidemiologic data on coworkers, and liver biopsy specimens. The high prevalence of unsuspected liver enzyme abnormalities in these workers suggests that occupational liver disease may occur more frequently than is generally recognized.

A hospital-based case-control study of stillbirths and environmental exposure to arsenic using an atmospheric dispersion model linked to a geographical information system.

Although adverse reproductive outcomes have been associated with arsenic exposure, the extent and severity of the effects of chronic inhalation of low levels of arsenic on reproduction are not known. We conducted a hospital-based case-control study of stillbirths in a central Texas community that included a facility with more than a 60-year history of producing primarily arsenic-based agricultural products. We collected data on 119 cases and 267 controls randomly selected from healthy live-births at the same hospital and matched for year of birth. We abstracted medical and demographic data for the period January 1, 1983, to December 31, 1993, from hospital records and estimated socioeconomic status by median income from the 1990 Population and Housing Census data. We estimated arsenic exposure levels from airborne emission estimates and an atmospheric dispersion model and linked the results to a geographical information system (GIS) database. Exposure was linked by GIS to residential address at time of delivery. A conditional logistic regression model was fitted including maternal age, race/ethnicity, parity, income group, exposure as a categorical variable, and exposure-race/ethnicity interaction. The prevalence odds ratio observed for Hispanics in the highexposure group (>100 ng per m3 arsenic) was 8.4, with a 95% confidence interval of 1.4–50.1. (Epidemiology 1998;9: 290–294)

Occupational risk factors and Alzheimer's disease: a case-control study

A case-control study was conducted to assess occupational exposure to organic solvents and lead as risk factors for Alzheimers disease. All case subjects were diagnosed at a Veterans Administration Hospital in Bedford, Massachusetts. Control subjects were selected from Massachusetts voter registration lists and matched by sex, year of birth, and town of residence. Information on occupational history was assessed by mailed questionnaire sent to the spouse or next of kin of the study subject. A total of 98 case and 162 control subjects were included in the matched analysis. No apparent association of increased risk of Alzheimers disease was observed for ever having occupational exposure to organic solvents or lead.

Disease clusters : a central and ongoing role in occupational health

To review and evaluate whether the investigation of disease clusters continues to play an important role in establishing disease-toxin connections in the workplace, 87 original disease cluster reports were identified that established disease-toxin connections in occupational medicine (from 1775 to 1990). Four advantages of the workplace with regard to cluster discovery and investigation were identified: natural denominator boundaries, shared exposures, the ability to form intermediate hypotheses, and the possibility of locating comparable populations in which to study these hypotheses. Because new products, intermediate products, and procedures are introduced into working environments faster than epidemiologic and toxicologic studies can be designed to evaluate their potential risks, disease cluster investigations will remain central to the understanding of disease, and to protecting workers.

Epidemiologic patterns of frontal and maxillary sinus cancer

A significant decrease in mortality rates for maxillary and frontal sinus cancer was found for older females, particularly in urban areas of New York State, over a 30‐year period. A similar observation was made for males residing in rural areas. The decline in female rates might be related to the discontinued use of carcinogenic agents such as Thorotrast, whereas that in males might be related to changes in those industries associated with an increased risk for these cancer sites.