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Background: Both women's and men's occupational health problems merit scientific attention. Researchers need to consider the effect of gender on how occupational health issues are experienced, expressed, defined, and addressed. More serious consideration of gender-related factors will help identify risk factors for both women and men., Methods: The authors, who come from a number of disciplines (ergonomics, epidemiology, public health, social medicine, community psychology, economics, sociology) pooled their critiques in order to arrive at the most common and significant problems faced by occupational health researchers who wish to consider gender appropriately., Results: This paper describes some ways that gender can be and has been handled in studies of occupational health, as well as some of the consequences. The paper also suggests specific research practices that avoid errors. Obstacles to gender-sensitive practices are considered., Conclusions: Although gender-sensitive practices may be difficult to operationalize in some cases, they enrich the scientific quality of research and should lead to better data and ultimately to well-targeted prevention programs., (Copyright 2003 Wiley-Liss, Inc.)

Background: Several researchers have proposed fiber size ranges representing hypotheses about the biological activity of fibers. Each of these indices has a biologically plausible rationale, yet they propose different fiber dimensions., Methods: Four biologically based and one standard fiber analytic method index, the NIOSH 7400 method with B rules, were evaluated in air monitoring data collected in a variety of fiber glass (FG) manufacturing settings to determine their impact on an assessment of fiber exposure for an epidemiologic study of the risk of respiratory cancer among FG production workers., Results: All indices varied considerably within and among the range of fiber size distributions sampled in the FG factories., Conclusions: The asymptotic relative efficiencies (R(2)) calculated among the five indices indicate a potentially important loss of power from the use of the standard method index, if one of the biologically based indices is more closely related to the disease outcome in an epidemiologic study., (Copyright 2000 Wiley-Liss, Inc.)

The National Research Council's report "Protecting Youth at Work" addresses the health and safety consequences of work by youth in the United States. The report finds that a higher proportion of U.S. youth work than in any other developed nation and that as much as 80% of youth will have worked during their high school years. The majority of adolescents are employed in the retail and service sectors. Positive aspects of this work include lessons in responsibility, punctuality, dealing with people, good money management, and gaining self-esteem, independence and new skills. On the negative side, however, students who work long hours are less likely to advance as far in school as other students, are more likely to smoke cigarettes and use illegal drugs, be involved in other deviant behavior, may get insufficient sleep and exercise, and may spend less time with their family. Working youth appear to have injury rates (4.9 per 100 FTE) almost twice that of adult workers (2.8 per 100 FTE). There is evidence that each year over 200,000 youth experience work injuries and at least 70 die. The report includes an extensive list of recommendations to safeguard the health and well-being of young workers: improved government regulations as well as their enforcement, better data collection and analysis to provide essential information on the distribution and consequences of youth employment, education of key actors such as employers, parents, teachers and the youth themselves, and research to fill critical knowledge gaps., (Copyright 1999 Wiley-Liss, Inc.)

Background: To evaluate the relationship between long-term exposure to cotton dust and Gram-negative bacterial endotoxin on lung function, we conducted an 11-year follow-up study of cotton textile workers in Shanghai, China., Methods: Workers at a nearby silk-thread manufacturing mill were used as a referent population. Ninety percent of the original cohort of 445 cotton and 467 silk textile workers--both active and retired--were identified for testing in the 11th year. Questionnaires and spirometric testing were performed, as well as cotton dust and endotoxin sampling at three points over the 11-year follow-up period: at baseline, at Year 5, and at Year 11. After excluding deaths and subjects on sick-leave, 84% of the original cohort had complete health and environmental data., Results: The data were reanalyzed using generalized estimating equations feedback model which allow for subject transfer over time between work areas, various exposure levels to dust and endotoxin, and FEV1. Cotton workers had a larger loss of FEV1 during the first 5 years of study (-40 mls/yr) as compared with the second 6 years of follow-up (-18 mls/yr). During the same periods, the average decline among silk workers was slightly higher in the first period, but was more consistent (-30 mls/yr vs. -27 mls/yr), and these differences could not be explained by worker selection or dropout. When cumulative exposure to dust and endotoxin were estimated and used in a multivariate model (GEE) for FEV1 loss, cumulative dust, but not endotoxin, was associated with 11-year loss in FEV1 after adjustments for confounders. There was evidence of feedback between dust-exposure levels and FEV1, indicating the existence of a healthy-worker survivor effect. After accounting for a healthy-worker survivor effect, we found a significant relationship between dust exposure and FEV1 decline., Conclusions: Our results suggest that cotton dust is more strongly associated with chronic airflow limitation than associated endotoxins. Further work is needed to clarify potential reversibility after cessation of exposure, and the relative contributions of dust, endotoxin, and tobacco to chronic respiratory impairment in cotton and other vegetable-exposed workers.

This study examines the determinants of susceptibility to the irritant effects of sodium borate in 18 responsive workers identified through repeated self-reports of nasal irritation. For each worker, susceptibility was characterized by two features; reactivity and sensitivity, as estimated from the slope and intercept parameters from their individual exposure-response regression model. Individual estimates of reactivity and sensitivity were then examined to evaluate the importance of personal and environmental characteristics in determining susceptibility. The use of nasal sprays, current smoking and allergies were associated with lower reactivity, while high exposures to borate dust were associated with higher sensitivity. To examine possible biologic mechanisms for the irritant response, a toxicokinetic dose model was used to calculate nasal osmolarity during symptom intervals. The estimated levels suggest that osmolar activation of mast cells to release histamine and other mediators is a plausible mechanism by which these workers may experience nasal irritation.

Background: Results are reported from a nested case-control study of 60 esophageal cancer deaths among 46,384 automobile manufacturing workers potentially exposed to metalworking fluids (MWF) in machining and grinding operations., Methods: By using incidence-density sampling, controls were selected with a sampling ratio of 20:1 from among co-workers who remained at risk by the age of death of the case, matched on race, gender, plant, and year of birth. Conditional logistic regression was used to evaluate the risk associated with cumulative exposure (mg/m3-years) to each of three types of metalworking fluid (straight, soluble, and synthetic MWF), as well as with years of exposure to selected components of MWF, including nitrosamines, sulfur, biocides, and several metals., Results: Esophageal cancer was found to be significantly associated with exposure to both soluble and synthetic MWF in grinding operations. The odds ratios (ORs) for grinding with soluble MWF were elevated at 2.5 or greater in all categories of cumulative exposure, although the exposure-response trend was statistically significant only when exposure was measured as duration. Those with 12 or more years exposure to soluble MWF in grinding operations experienced a 9.3-fold relative risk of esophageal cancer mortality (95% CI = 2.1-42.1). The OR for ever grinding with synthetic MWF was 4.1 (95% CI = 1.1-15.0). Elevated risk was also associated with two agents found in both synthetic and soluble fluids, nitrosamines, and biocides. For exposure to nitrosamines, the OR was 5.4 (95% CI = 1.5-19.9); for biocides the OR was 3.8 (95% CI = 0.8-18.9). However, because the same workers were exposed to grinding with synthetics, nitrosamines and biocides, it was not possible to separate the specific risks associated with these components.

An investigation of the acute respiratory effects of workers exposed to metal working fluids (MWF) was conducted in an automobile parts manufacturing facility. After observing an association between cross-shift decline in forced expiratory volume in the first second (FEV1) and aerosol mass concentration, improved characterization of the exposure was sought through investigation of four elements of a priori interest (Cl, Cr, Ni, S). Of these, only sulfur showed an association with cross-shift FEV1 decrement. The relative risk of 5% cross-shift FEV1 decrement was 2.7 (95% confidence interval = 1.0-6.0) comparing those with > 4.4 micrograms/m3 to those with < 2.5 micrograms/m3 sulfur exposure. Because the concentrations of sulfur in this environment were relatively low and other respiratory irritants were present, sulfur is more likely to be an indicator of more irritating conditions than the sole agent responsible for the observed acute respiratory effects.

This report describes the reanalysis of a cross-sectional study of asthma in a large cohort of autoworkers with exposure to metalworking fluids (MWF). There is strong evidence from case reports, clinical studies, and medical surveillance data that exposure to MWF can cause asthma, yet no association was found in the original analysis. The central hypothesis of the reanalysis was that the absence of an association between asthma and MWF exposure was the result of bias caused by the self-selection of asthmatics out of exposed jobs. We addressed the potential job transfer bias by redefining exposure and disease status at the time of asthma onset, rather than at the time of the health survey. This permitted us to treat the cross-sectional study as if it were a historical cohort study, despite the fact that the population was a biased sample of the full cohort. This approach resulted in a significantly elevated incidence rate ratio of 3.2 (95% CI: 1.2-8.3) for synthetic MWF estimated in a Cox proportional hazards model. Although the cross-sectional design makes it impossible to document or control for differential selection out of the workforce, the approach described here provides a strategy for reducing the healthy-worker effect due to job transfer bias in cross-sectional studies.

The outline for a workshop discussion of intervention research in manufacturing industry is presented. The example used is the control of machining fluid exposures, a widespread exposure that is associated with risk of cancer, pulmonary disease, dermatitis, and several types of accident-related injuries. Relevant technical considerations for conducting intervention research include the selection of machining fluid for different machining purposes, the management of fluids in use, and the selection and maintenance of environmental controls. Equally important are nontechnical considerations including the need for creating labor-management health and safety committees, the use of administrative rules on job performance for both workers and management, and training on the role of individuals from either group in exposure control. Clarity concerning the objectives for an intervention study and plans for clear means to evaluate study outcomes is critical. Important study variables will include site selection, plant size, plant demographics, the involvement of workers in the study, a willing management, and concern for susceptible workers.

Exposure to cotton dust is known to cause both acute and chronic respiratory illness. A specific pattern of symptoms called byssinosis is well described to occur among workers in the cotton processing (e.g., yarn preparation) industry. Recent studies have implicated Gram-negative bacterial endotoxin as one of the agents responsible for acute, and possibly chronic, respiratory illness. Laboratory experiments using a model cardroom have found poor correlations between airborne dust and associated endotoxin. This study reports the results of vertical elutriated dust and endotoxin levels in 11 work areas of 2 cotton textile mills in 1986 in Shanghai, China. The overall correlation between dust and endotoxin was strong, rs = 0.66 and 0.79 (p < 0.0001) for mills 1 and 2, respectively. The dust-endotoxin correlation was relatively poor in early yarn preparation in the workshops and improved in the later preparation areas. Our findings suggest that in these mill settings, dust and endotoxin levels may be well correlated in most work areas. Therefore, dust may be a useful index for monitoring populations employed in the cotton textile industry throughout the world. Additional field studies need to be performed which consider the various determinants of dust and endotoxin levels.

This report explores the importance of characterizing short-term (peak) exposures for successful epidemiologic study of acute reversible effects. By selecting upper respiratory tract irritation, which is time-limited, reversible, and not critically affected by host factor sensitivities, the illustrated approach (directed at an acute respiratory irritant) provides insights on issues important in the general study of acute effects. The fundamental concern in a study of acute irritant effects is that such events occur in response to abrupt increases in exposure. This calls for a closer examination of how to distinguish bursts, or peaks, of exposure from continuous exposures measured simply as time weighted averages. Three parameters of peak exposures are discussed: duration, magnitude, and frequency. The importance of duration is illustrated by contrasting exposure patterns relevant for the study of acute vs. chronic health effects. The minimum magnitude of a peak relevant to the study of a specific physiologic response requires knowledge of the threshold below which no detectable response occurs. For any identified threshold level, only exposures exceeding that level are defined as relevant peaks for an exposure-response analysis. Finally, the issue of frequency, the minimum length of time between successive exposures necessary for the subject to return to baseline risk, is explored. A study of respiratory irritation associated with sodium borates is used to illustrate these issues.

A Health Hazard Evaluation was conducted by the National Institute for Occupational Safety and Health in an area of a large chemical plant that manufactured the stilbene derivative 4,4'-diaminostilbene-2,2'-disulfonic acid, an intermediate used for the production of optical brightening agents. Men employed in the area reported problems with impotence. The study population consisted of 44 men aged 20-57 years (mean age 37) employed in the area at the time of the evaluation. An industrial hygiene investigation, health and work history questionnaire survey, physical examinations, and blood chemistry and serum hormone evaluation were conducted. Fourteen percent of the men reported symptoms of impotence over the preceding 6 or more months, 7% had potency problems of shorter duration, and 7% were not currently impotent but had experienced impotence for 6 or more months in the past; 36% experienced decreased libido, all since beginning work in the production area. Low levels of serum testosterone (less than 350 ng/dl) were observed in 37% of the men. The low serum testosterone concentrations were not accounted for fully by diurnal variation or an effect of rotating shift work. It is suggested that exposures to chemicals possessing estrogenic activity may be related to the observed health effects in these workers.

Occupational exposure to lead represents a continuing problem of significant magnitude in the United States. To characterize the problem for surveillance purposes, an analysis of the airborne concentrations of lead identified in OSHA compliance inspections was conducted for the years 1979 to 1985. The five specific objectives of the study were: 1) to examine the distribution of air lead concentration in industrial environments; 2) to determine the secular trends in air lead concentrations for high lead industries; 3) to assess which job titles had excessive airborne lead concentrations; 4) to evaluate whether there was a relationship between lead overexposure and company size, unionization, or type of inspection; and 5) to investigate the prevalence of respirator violations for lead. Fifty-two industries were identified which had more than 1/3 of their inspection medians greater than the permissible exposure limit. These included primary and secondary lead smelting, battery manufacture, pigment manufacture, brass/bronze foundries, as well as 46 other industries. There has been little if any improvement in the prevalence and severity of airborne lead concentrations for the high lead industries, battery manufacture, secondary smelting, pigment manufacture, and brass/bronze foundries. Specific high exposure job titles are identified for certain high lead industries. The job title of painting stands out as an especially problematical job title across a number of industries. The prevalence of respirator violations is approximately 20% of all lead inspections.

This paper reviews the known respiratory effects of isocyanates. There is good evidence to indicate that isocyanates: cause chemical bronchitis/pneumonitis; are potent pulmonary sensitizers capable of causing "isocyanate asthma"; cause nonspecific airways disease, including chronic bronchitis; can induce a general asthmatic state; and can cause hypersensitivity pneumonitis. Similar dose-response relationships are seen for both acute and chronic effects. There are plants operating in which exposures are well controlled and in which no respiratory effects can be detected. Suggestions are provided for preplacement assessment and periodic surveillance for workers exposed to these compounds.

A four-year longitudinal study of ventilatory function in polyurethane-foam production workers exposed to toluene diisocyanate (TDI) revealed a dose-response relationship between average exposure to TDI and change in forced expiratory volume per second (FEV-1). Workers with mean exposure in excess of 0.0035 ppm showed a greater rate of decline of FEV-1 over the four-year period than that expected from aging. Factors other than TDI exposure (sex, smoking history, history of atopy) do not account for the loss. The current threshold limit value (TLV) for exposure to TDI in industry (0.02 ppm) does not protect workers from accelerated impairment of ventilatory capacity.

A properly designed respiratory disease monitoring and surveillance program for the effects of cotton dust uses tools similar to those used clinically but provides a different focus--the potential for disease prevention in individuals and the control of excess exposures in groups. Both surveillance and monitoring require the use of standard instruments (questionnaires and pulmonary function equipment) with careful attention to equipment calibration and standard methods for administering tests. Monitoring focuses on the individual to identify early evidence of disease and to detect those subjects who are susceptible even under usually well controlled exposure circumstances. Surveillance is successful when designed to collect information at regular intervals (based on type and level of exposure and previously measured response) and the results are interpreted according to reasonably rigorous criteria. A major additional component is the examination of surveillance results according to groups based on job, exposure, work tenure, and other risk factors (e.g., smoking).

Exchanges between U.S. and Chinese professionals have provided opportunities for observation of recent developments in occupational health in China. For the past decade, China has been committed to an unprecedented drive for economic modernization, including new policies on ownership, business management, employment, health care, and disability as well as increased activity in heavy, light, and service industries. Chinese occupational health professionals and labor organizations have set a goal of modernizing worker health along with the rest of society. Examples of advances in occupational health occurring since 1981 are the coordination of industrial hygiene and health research and services, an emphasis on epidemiology, interdisciplinary approaches to problem-solving, the pretesting of toxic substances, regulation and standard setting, and on-site workplace hazard prevention.

This study examines cancer mortality patterns by occupation for white males in Massachusetts using 1971-1973 death records. Its purpose is to identify occupation-cancer associations that, when interpreted in conjunction with results from other studies and hypotheses about potential occupational carcinogens, can serve as leads for more definitive etiological investigations. Sixty-two malignancy categories (including grouped categories) were investigated for each of 397 occupational categories (including grouped categories) using an age-standardized mortality odds ratio approach. An important finding was the association between lung cancer and a large number of occupations for which there is support from other epidemiologic studies and/or for which there are reasonable hypotheses as to possible carcinogenic exposures. These occupations include truck drivers, painters, machinists, automobile mechanics, plumbers, cooks, fishermen, heated metal workers, sheet metal workers, and brickmasons/stonemasons/tile setters.

Recent studies identify digestive cancer excesses among workers exposed to cutting fluids, abrasive dusts, and oil smoke. Standardized proportional mortality and mortality odds ratio studies were carried out for a ball bearing plant. Cause of death and work histories were obtained for 702 of 768 hourly employees with ten or more years' service who died between 1969 and 1982. Union and company records were used to define exposure measures. The major findings were significant excesses in proportional mortality ratios (PMR) from stomach cancer (PMR = 2.0) and rectal cancer (PMR = 3.1) among white men. After control for age at death, there was a significant association between stomach cancer and precision grinding exposures, consisting primarily of direct contact with water-based cutting fluids (usually emulsified oils) and their aerosols. Some straight oils and synthetic cutting fluids were used as well. The pattern of stomach cancer is consistent with previous findings and suggests an association with the soluble oil cutting fluids.

Epidemiologic approaches to improved understanding of the several reactions observed in cotton processors began in 1955 with Schilling's symptom classification of Monday-morning chest tightness. To date, epidemiologic studies have identified the importance of increasing years of exposure to the development of both specific and nonspecific chronic respiratory symptoms and of acute change in pulmonary function. The few longitudinal studies suggest similar associations with accelerated loss of pulmonary function. Respirable dust level has been associated, cross-sectionally, with symptoms and with acute function change, but studies have not yet been made with sufficient prospective collection of both exposure and health effects data to estimate accurately the association of continued exposure with accelerated loss of lung function or development of disability. Furthermore, there has been very limited field study comparing exposure to respirable dust distinguished from exposure to endotoxin. With careful attention to features of study design and analytic plans, investigators can take advantage of simple technology to examine the fate of the acute responder, the potential for recovery if exposure is reduced or ceased, and the long-term dose response relationship between different cumulative measures of exposure and chronic disease.

One hundred forty-four sewing machine operators answered questionnaires concerning occupational history and musculoskeletal symptoms adapted from the National Health and Nutrition Examination Survey. They were matched for age within 5 years, race, and sex with persons completing the HANES I Augmentation Survey, and the prevalence of self-reported musculoskeletal morbidity was compared. Operators complained significantly more often of knee pain (prevalence odds ratio [POR] = 1.84, p = .0001) and knee swelling (POR = 9.98, p less than .00001), although they were no more likely to have had knee surgery. Similar increases were reported for upper-back pain (POR = 2.13, p = .002) joint ache, and joint swelling (both were significant for fingers, wrists, elbows, and shoulders at p less than .05 levels). No differences in low-back pain or in hospitalization for joint conditions were noted. Ergonomic redesign of sewing machines needs to address knee and upper-back movements as well as the arm, wrist, and finger movements.

A proportional mortality analysis of death certificates of 2,798 shoe and leather workers demonstrated a statistically significant excess of bladder cancer among female shoe workers (PMR = 2.51, 95% confidence interval 1.23 to 5.12). A case-referent analysis of 289 leather workers, on whom detailed occupational information was available, demonstrated an association of lung cancer with work in leather-tanning jobs (odds ratio = 4.2, 95% confidence interval 1.09 to 16.2).

The size distribution measurements of lead aerosol from a brass foundry and primary lead smelter are used to simulate blood lead distributions applying a pharmacokinetic model developed by Bernard. The predicted distribution of blood lead levels determined using the actual size distribution of lead aerosol are compared to the blood lead levels predicted according to the model assumptions adopted in setting the OSHA lead standard. In the furnace area of the smelter and the pouring area of the foundry the predicted mean blood lead level is higher than that found in the standard whereas, in the smelter's sintering and mixing operation the blood lead level is less than that suggested by the standard. The data support the conclusion that size-selective sampling needs to be considered for incorporation into the OSHA lead standard.

The proportional mortality experience (1952-1978) of 969 deceased white male granite workers was compared with that of United States white males. Industrial hygiene information was combined with work histories to develop an estimate of lifetime granite dust exposure for each individual. Subjects were grouped into four cumulative exposure categories, and exposure-response relationships were examined. Trends of increasing silicosis and tuberculosis with increasing lifetime exposure were observed. These are consistent with earlier findings. With the exception of excess suicide among granite workers dying before 1970, there was little evidence of association between other causes of death and employment in the granite industry.

Quantitative evaluation of worker exposure to silica in nine Standard Industrial Classification (SIC) codes was conducted, using data derived from OSHA compliance inspections, in order to assess the silica exposure problem in the U.S. The nine SICs studied were those in which OSHA inspections were concentrated. They include: construction; chemical manufacture; stone, glass, and clay manufacturing; primary metal industries; metal fabrication; machinery; transportation; and miscellaneous manufacturing industries. High exposures to silica were documented in each industry, with the number of test samples over the permissible exposure limit ranging from 14% (aluminum foundries) to 73% (pottery). An estimation is made that 24,889 workers employed in ferrous and nonferrous foundries are at risk of silica-related pulmonary effects. The data developed in this analysis also indicate the need to investigate certain industries that had high exposures but few inspections. The limitations of the data base for estimating the scope of the silica problem, including lack of data on mining and milling, are discussed. We conclude that exposure to silica represents a continuing and significant problem in a number of U.S. industries.