PubMed Health⌕ Search

Biomedical subjects

M B Schenker

Publications and source records attributed to M B Schenker.

At least 73 records · Page 4Linked to original sources
PubMed1990

Adverse reproductive outcomes among female veterinarians.

Because female veterinarians are exposed to several known reproductive hazards, the authors conducted a reproductive survey of all female graduates of a US veterinary school (n = 537) and law school (comparison group, n = 794). Analysis was confined to pregnancies completed after the second year of professional school and from 1966 to 1986. Based on one randomly chosen eligible pregnancy per woman (veterinarians, n = 176; lawyers, n = 229), spontaneous abortion rates, adjusted for elective abortions, were 13.3% for the veterinarians and 15.1% for the lawyers; these did not differ significantly. A Cox life table regression model controlling for age, smoking, alcohol use, and prior spontaneous abortion also showed no significant difference in spontaneous abortion rates between the two populations. Using all pregnancies, veterinarians who reported performing five or more radiographic examinations per week had a marginally elevated risk of spontaneous abortion, but the statistical significance disappeared when analysis was limited to one random pregnancy per woman. For one random eligible birth per woman, the mean birth weight did not differ significantly between the veterinarians and lawyers, even after controlling for possible confounders in regression analyses. A higher rate of reportable birth defects was observed among the veterinarians than among the lawyers (relative risk = 4.2, 95% confidence interval 1.2-15.1), but this unexpected result must be considered hypothesis-generating. The authors did not find an overall increased risk for spontaneous abortion or low birth weight infants among veterinarians compared with lawyers, but veterinarians who reported performing five or more radiographic examinations per week may have been at increased risk for spontaneous abortion.

Abortion, Incomplete↗
PubMed1990

Markers of exposure to diesel exhaust in railroad workers.

Diesel exhaust is a known mutagen and a potential human carcinogen. Recent epidemiological studies have demonstrated a small increase in the risk of lung cancer from diesel exhaust exposure. However, many epidemiological studies have used crude estimates of exposure, and even accurate measures of exposure may not be accurate estimates of the internal dose received. Measurement of diesel exhaust exposure also has been limited by the absence of a standard marker. This study was undertaken to evaluate the usefulness of urinary mutagenicity as a biological marker of diesel exhaust exposure in the workplace. We measured the exposure of individual railroad workers to diesel exhaust by using personal air samples taken over two consecutive work shifts. Nicotine in the samples was measured to adjust the respirable particle concentrations for active and passive cigarette smoking. Urine samples were collected at the end of the study work shifts and were analyzed for markers of cigarette smoking (nicotine, cotinine) and for mutagenicity, using a sensitive microsuspension assay (micro preincubation assay; Salmonella strain TA98 with or without S9 enzyme). The number of cigarettes smoked on the study shift was recorded, and subjects completed a questionnaire at the end of the second day on personal habits and exposures at home and work. Multiple regression analyses were used to analyze independent determinants of urinary mutagenicity, including a generalized least-squares analysis that divided residual variation into between- and within-person components. Eighty-seven subjects completed 151 two-day protocols; an additional four subjects provided usable data for a single day (n = 306 samples). Respirable particle concentration was not a good marker of diesel exhaust exposure when contamination by environmental tobacco smoke existed in the work location, but respirable particle concentration that was adjusted for environmental tobacco smoke correlated with a priori assessments of diesel exhaust exposure by job grouping. Phenanthrene concentration, as a potential marker, was measured in a subset of personal samples, and correlated with known diesel exhaust exposure by job grouping. A constant ratio of phenanthrene to respirable particles in area samples from diesel exhaust-exposed work locations suggested that phenanthrene is promising as a marker for diesel exhaust. Mutagenic activity was also measured from extracts of respirable particles in a few personal filter samples, and this technique may be useful for further investigation in epidemiological studies.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants, Occupational↗
PubMed1989

Occupational injury and illness in the semiconductor manufacturing industry.

Two thousand nine hundred and ninety-four reports of OSHA-reportable occupational injury or illness cases in 1984 from member companies of a national trade association of semiconductor manufacturing firms were analyzed. The 37 participating manufacturing facilities represented 16 companies employing over 95,000 persons, or approximately one-third of the U.S. work force for this industry in 1984. The annual incidence rate for all reportable injuries and illnesses was 2.7 per 100 full-time employees (FTE) for men and 3.7 per 100 FTE for women. Strains, sprains, or dislocations were the most frequently reported incidents (N = 956 [31.9%]), followed by cuts, lacerations, punctures, scratches, and abrasions (N = 445 [14.9%]), and chemical burns (N = 401 [13.4%]). Increased work-loss days per case were associated with manufacturing sites that did not have an employee health clinic on the premises, with custodial occupations, and with female gender.

Data Collection↗
PubMed1989

Prevalence of hazardous exposures in veterinary practice.

All female graduates of a major U.S. veterinary school were surveyed by mailed questionnaire to obtain details of work practice and hazard exposure during the most recent year worked and during all pregnancies. Exposure questions were based on previously implicated occupational hazards which included anesthetic gases, radiation, zoonoses, prostaglandins, vaccines, physical trauma, and pesticides. The response rate was 86% (462/537). We found that practice type and pregnancy status were major determinants of hazard exposure within the veterinary profession. Small-animal practitioners reported the highest rates of exposure to anesthetic gas (94%), X-ray (90%), and pesticides (57%). Large-animal practitioners reported greater rates of trauma (64%) and potential exposure to prostaglandins (92%), Brucella abortus vaccine (23%), and carbon monoxide (18%). Potentially hazardous workplace practices or equipment were common. Forty-one percent of respondents who reported taking X-rays did not wear film badges, and 76% reported physically restraining animals for X-ray procedures. Twenty-seven percent of the respondents exposed to anesthetic gases worked at facilities which did not have waste anesthetic gas scavenging systems. Women who worked as veterinarians during a pregnancy attempted to reduce exposures to X-rays, insecticides, and other potentially hazardous exposures. Some potentially hazardous workplace exposures are common in veterinary practice, and measures to educate workers and to reduce these exposures should not await demonstration of adverse health effects.

Anesthetics↗
PubMed1989

Assessing dermatitis in epidemiologic studies: occupational skin disease among California grape and tomato harvesters.

We conducted a cross-sectional investigation to determine whether table grape harvesters, who have significant cutaneous contact with crop-associated materials that may cause skin disease, are more likely to develop dermatitis than are a control group of tomato workers performing mechanical harvesting with minimal cutaneous contact with crop-associated substances. A secondary aim was to develop methods for studying skin disease in farm workers, including a standard questionnaire and physical examination. California table grape workers (n = 183) and tomato workers (n = 43) completed an interviewer-administered questionnaire and waist-up physical examination at their work site during harvest operations. On physical examination, pustular eruptions such as acne and folliculitis were present in 30% of subjects, and eczematous rashes were noted in 10% of subjects. Irritant or allergic contact dermatitis was diagnosed in 2% of subjects. No significant differences in prevalence for these skin conditions were observed between the two groups of workers. In contrast to the physical examination results, grape workers were more likely than tomato workers to report a rash occurring in the previous 3 months (52% vs. 19%, p less than 0.001). Explanations for this discrepancy are discussed. The sensitivity of the questionnaire for current skin conditions was 31%, and the specificity was 94%. Improved sensitivity was seen for eczematous skin conditions (55%). We conclude that questionnaires provide an efficient means of assessing subject characteristics, but may have limited sensitivity for some dermatologic outcomes.

Agricultural Workers' Diseases↗
PubMed1989

Occupational health in developing nations: the case of China.

The need for a comprehensive view of occupational health problems in developing nations was suggested by a recent occupational health delegation to China. Such problems in most developing nations are superimposed on a background of scarce economic resources, rapid industrialization, and socioeconomic dislocation as well as a poor nutritional and general health status of the population. Occupational health problems are exacerbated in these countries by the presence of a high proportion of very small firms, inadequate attention to industrial hygiene and ergonomic principles for worker health and safety, and a lack of toxicologic and epidemiologic data. The peculiar case of China is noted, wherein only some of the characteristics of a developing nation are exhibited. The Chinese model for occupational health as observed in a spectrum of industries including textiles, paint, and steel is described. Recent political and economic developments are discussed along with their implications for Chinese health policy in general and for occupational health practice in particular.

China↗
PubMed1989

Current nitrogen dioxide exposures among railroad workers.

As part of a series of epidemiologic studies of the mortality patterns of railroad workers, various air contaminants were measured to characterize the workers' current exposures to diesel exhaust. Nitrogen dioxide (NO2), which is a constituent of diesel exhaust, was examined as one possible marker of diesel exposure. An adaptation of the Palmes personal passive sampler was used to measure the NO2 exposures of 477 U.S. railroad workers at four railroads. The range of NO2 exposures expressed as the arithmetic average +/- two standard errors for the five career job groups were as follows: signal maintainers, 16-24 parts per billion (ppb); clerks/dispatchers/station agents, 23-43 ppb; engineers/firers, 26-38 ppb; brakers/conductors, 50-74 ppb; and locomotive shop workers, 95-127 ppb. Variations among railroads and across seasons were not significant for most job groups.

Air Pollutants, Occupational↗
PubMed1988

Estimation of the diesel exhaust exposures of railroad workers: I. Current exposures.

As a part of a series of epidemiological studies of railroad workers, measurements were made to characterize workers' exposures to diesel exhaust. Since diesel exhaust is not a single compound, an exposure marker was sought. The personal exposures to respirable particulate matter (RPM) of over 530 workers in 39 common jobs were measured in four U.S. railroads over a three-year period. Significant amounts of cigarette smoke (20-90%) were found in many of these samples. Therefore, the respirable particulate concentration, adjusted to remove the fraction of cigarette smoke (ARP), was chosen as a marker of diesel exhaust exposures. The geometric mean exposures to ARP ranged from 17 micrograms/m3 for clerks to 134 micrograms/m3 for locomotive shop workers. Significant interrailroad variations were observed in some job groups indicating that the different facilities, equipment, and work practices found among the railroads can affect a worker's exposure to diesel exhaust. Climate was also found to have a significant effect on exposure in some job groups.

Air Pollutants, Occupational↗
PubMed1988

Estimation of the diesel exhaust exposures of railroad workers: II. National and historical exposures.

The diesel exhaust exposures of railroad workers in thirteen job groups from four railroads in the United States were used to estimate U.S. national average exposures with a linear statistical model which accounts for the significant variability in exposure caused by climate, the differences among railroads and the uneven distribution of railroad workers across climatic regions. Personal measurements of respirable particulate matter, adjusted to remove the contribution of cigarette smoke particles, were used as a marker for diesel exhaust. The estimated national means of adjusted respirable particulate matter (ARP) averaged 10 micrograms/m3 lower than the simple means for each job group, reflecting the climatic differences between the northern railroads studied and the distribution of railroad workers nationally. Limited historical records, including some industrial hygiene data, were used to evaluate past diesel exhaust exposures, which were estimated to be approximately constant from the 1950's to 1983.

Air Pollutants, Occupational↗
PubMed1988

A retrospective cohort study of lung cancer and diesel exhaust exposure in railroad workers.

The risk of lung cancer as a result of exposure to diesel exhaust from railroad locomotives was assessed in a cohort of 55,407 white male railroad workers 40 to 64 yr of age in 1959 who had started railroad service 10 to 20 years earlier. The cohort was traced until the end of 1980, and death certificates were obtained for 88% of 19,396 deaths; 1,694 lung cancer cases were identified. Yearly railroad job from 1959 to death or retirement was available from the Railroad Retirement Board, and served as an index of diesel exhaust exposure. Directly standardized rates and a proportional hazards model were used to calculate the relative risk of lung cancer based on work in a job with diesel exhaust exposure beginning in 1959. A relative risk of 1.45 (95% CI = 1.11, 1.89) for lung cancer was obtained in the group of workers 40 to 44 yr of age in 1959, the group with the longest possible duration of diesel exposure. The cohort was selected to minimize the effect of past railroad asbestos exposure, and analysis with workers with possible asbestos exposure excluded resulted in a similarly elevated risk. Workers with 20 yr or more elapsed since 1959, the effective start of diesel exposure for the cohort, had the highest relative risk. These results taken in conjunction with other reported results support the hypothesis that occupational exposure to diesel exhaust results in a small but significantly elevated risk for lung cancer.

Adult↗
PubMed1988

Prospective surveillance of semen quality in the workplace.

We performed a prospective surveillance of semen quality among workers in the plant where 1,2-dibromo-3-chloropropane was first recognized as an occupational cause of impaired semen quality and of infertility. All male employees of the Agricultural Chemical Division were required to participate. Ninety-seven workers (92% participation) provided 258 semen samples over the 4 years of the program. Most samples were analyzed at the plant with a mini-laboratory designed for the study. Motility and shape measures were made objectively. Sixty-six subjects (68%) were non-azoospermic. Generalized multiple regression showed no significant predictors for any response, with the exception of the motility measures, which were reduced with longer times between ejaculation and assay. Between- and within-person standard deviations and correlations were calculated. Comparison of this population with fertile artificial insemination donors (16 men, 498 ejaculates) revealed generally higher ejaculate-to-ejaculate standard deviations in the worker samples. This is probably due to less well controlled conditions of sperm collection in the workplace setting. For cross-sectional studies, one ejaculate per worker is recommended as sufficient; for estimating an individual worker's mean, even three ejaculates may not provide enough precision.

Environmental Exposure↗
PubMed1987

Past exposure to asbestos among active railroad workers.

Before the transition from steam- to diesel-powered locomotives during the 1950s certain railroad workers had the opportunity for significant occupational exposure to asbestos. Past studies have demonstrated that older workers with jobs associated with the repair of steam locomotives had the most exposure. To determine the prevalence of currently employed railroad workers with past asbestos exposure we surveyed 514 white male employees of an active US railroad by mail questionnaire. Twenty-one percent (50/242) of the workers 50 years old or greater had likely asbestos exposure compared to 3% (9/275) of the workers 49 years old or less (p less than .001). Fifteen (30%) of the 50 older workers with likely asbestos exposure had current job titles no longer suggestive of past exposure. The duration of exposure of these older active workers was short, (median = 3 years; range, 6 months to 15 years). A history of past asbestos exposure may still be obtained among active railroad workers with past railroad shop employment.

Adult↗
PubMed1987

A case-control study of lung cancer and diesel exhaust exposure in railroad workers.

A case-control study of deaths among U.S. railroad workers was conducted to test the hypothesis that lung cancer is associated with exposure to diesel exhaust. Employed and retired male workers with greater than or equal to 10 yr of service who were born on or after January 1, 1900 and who died between March 1, 1981 and February 28, 1982 were eligible. We collected 87% of the death certificates from 15,059 deaths reported to the U.S. Railroad Retirement Board (RRB). Cases of lung cancer (1,256) were matched to controls by age (+/- 2.5 yr) and date of death (+/- 31 days). Potential exposure to diesel exhaust was assigned based on an industrial hygiene evaluation of jobs and work areas. Each subject's work history was determined from a yearly job report filed by his employer with the RRB from 1959 until death or retirement. Asbestos exposure prior to 1959 was categorized by the job held in 1959, the end of the steam locomotive era, or by the last job held if retirement occurred before 1959. Smoking histories were obtained by questionnaire from next of kin. Using multiple conditional logistic regression analysis to adjust for smoking and asbestos exposure, workers 64 yr of age or younger at the time of death with work in a diesel exhaust exposed job for 20 yr had a significantly increased relative odds (odds ratio = 1.41, 95% Cl = 1.06, 1.88) of lung cancer. No effect of diesel exhaust exposure was seen in workers 65 yr of age or older because many of these men retired shortly after the transition to diesel-powered locomotives.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1987

Daily air pollution effects on children's respiratory symptoms and peak expiratory flow.

To identify acute respiratory health effects associated with air pollution due to coal combustion, a subgroup of elementary school-aged children was selected from a large cross-sectional study and followed daily for eight months. Children were selected to obtain three equal-sized groups: one without respiratory symptoms, one with symptoms of persistent wheeze, and one with cough or phlegm production but without persistent wheeze. Parents completed a daily diary of symptoms from which illness constellations of upper respiratory illness (URI) and lower respiratory illness (LRI) and the symptom of wheeze were derived. Peak expiratory flow rate (PEFR) was measured daily for nine consecutive weeks during the eight-month study period. Maximum hourly concentrations of sulfur dioxide, nitrogen dioxide, ozone, and coefficient of haze for each 24-hour period, as well as minimum hourly temperature, were correlated with daily URI, LRI, wheeze, and PEFR using multiple regression models adjusting for illness occurrence or level of PEFR on the immediately preceding day. Respiratory illness on the preceding day was the most important predictor of current illness. A drop in temperature was associated with increased URI and LRI but not with increased wheeze or with a decrease in level of PEFR. No air pollutant was strongly associated with respiratory illness or with level of PEFR, either in the group of children as a whole, or in either of the symptomatic subgroups; the pollutant concentrations observed, however, were uniformly lower than current ambient air quality standards. Moreover, since exposure estimation based on monitoring of ambient air likely results in misclassification of the true exposure, the negative findings of this study must be interpreted cautiously.

Air Pollutants↗
PubMed1986

A population-based case-control study of mesothelioma deaths among U.S. railroad workers.

We have completed a case-control analysis of mesothelioma deaths among current and retired U.S. railroad employees. Cause-specific death certificates were obtained for 87% of 15,059 deaths reported by the railroad retirement board, and 20 mesotheliomas were identified according to death certificate diagnosis. A 10:1 matched analysis with railroad workers dying of nonmalignant, nonaccidental causes yielded a very strong association with prior railroad work in jobs with potential asbestos exposure (odds ratio = 7.2, 95% lower confidence limit = 3.3). Consideration of railroad occupations with regular asbestos exposures (e.g., skilled trades, steam locomotive repair) yielded an odds ratio of 21.4 (95% lower confidence limit = 8.7), but the occupations with potential intermittent exposure (e.g., engineers, firemen, carmen) yielded a nonsignificant odds ratio of 2.3 (95% lower confidence limit = 0.5). Applying mesothelioma mortality rates from this study to the population of U.S. railroad workers at risk yields an estimate of 416 cases of mesothelioma occurring among U.S. railroad workers between 1981 and 2000.

Adult↗
PubMed1984

Diesel exposure and mortality among railway workers: results of a pilot study.

A pilot study of the mortality of railway workers was undertaken to evaluate the feasibility of studying the association of exposure to diesel exhaust and cause specific mortality. The cohort consisted of 2519 white male subjects aged 45-64 with at least 10 years of railway service by 1967. Subjects were selected on the basis of job classification, and cause specific mortality was ascertained for subjects who died (n = 501) up to 1979. The total follow up period was 28.4 (X 1000) person-years. The standardised mortality ratio (SMR) for the cohort, based on United States national rates, was 87 (95% confidence limits 80, 95), and there were no significant differences from expected number of deaths for any specific neoplasm. The directly standardised rate ratio for respiratory cancer among diesel exposed subjects relative to unexposed subjects was 1.42 +/- 0.50 (means +/- SE). A proportional hazards model was consistent with the findings of the standardised rate ratio, but in neither analysis was the increased risk of respiratory cancer in diesel exposed subjects statistically significant.

Age Factors↗