Gender aspects in occupational exposure and health studies.

While sex is a biological attribute associated with physical and physiological features, gender refers to socially constructed roles, behaviors, expressions, and identities. On the biological side, males and females differ concerning hormonal and anatomical differences, and It is therefore plausible occupational exposure may act differently on males and females. In contrast, gender may influence the work organization, work environment conditions and exposures, and employment conditions, leading people of different genders to perform different jobs or job tasks, be exposed to different stressors, and work under different employment terms. Traditionally, occupational exposures have been assessed without considering how exposures may differ by sex or gender. Early research focused on occupations that primarily employed men. However, women have entered occupations historically dominated by men, leading to emerging exploration of gender differences in exposure. Some women-dominated occupations have become the focus of intensive research activity. In the Annals, the number of articles including sex and gender issues has increased dramatically over time, with only two published prior to 1980, and 70 in the 2010s, and with a special issue dedicated to Gender, Work, and Health in 2018 where the editors highlighted a need to improve assessment of gender and sex identities to allow for more nuanced knowledge to elucidate the role of work organization and contextual factors about gender, work exposures, and health. Females, on average, have different body dimensions than males, which affects how well workplaces and personal protective equipment (PPE) fit females, and there remains a need for further improvements to ensure that females are protected equally well. On the other hand, females tend to comply more frequently with PPE requirements than men highlighting the need for gender-specific initiatives in order to increase PPE performance and compliance. In conclusion, there is still work to do in order to fill in the existing knowledge gap with regard to sex, gender, and work, but there are promising initiatives and the field is progressing.

Environmental and occupational health on the Navajo Nation: a scoping review.

A scoping review was performed to answer: what environmental health concerns have been associated with adverse health outcomes in the Navajo Nation? The review focused on occupational and ambient environmental exposures associated with human industrial activities. The search strategy was implemented in PubMed, and two investigators screened the retrieved literature. Thirteen studies were included for review. Data were extracted using the matrix method. Six studies described associations between work in uranium mining and cancer. Six studies focused on environmental exposures to uranium mine waste and other metals, with outcomes that included biological markers, kidney disease, diabetes and hypertension, and adverse birth outcomes. One study explored occupational exposure to Sin Nombre Virus and infection. Most research has focused on the health effects of uranium, where occupational exposures occurred among miners and environmental exposures are a legacy of uranium mining and milling. Gaps exist with respect to health outcomes associated with current occupations and the psychosocial impact of environmental hazards. Other environmental exposures and hazards are known to exist on the Navajo Nation, which may warrant epidemiologic research.

Potential for occupational exposures to pathogens during bronchoscopy procedures.

Bronchoscopy is classified as an aerosol-generating procedure, but it is unclear what drives the elevated infection risk observed among healthcare personnel performing the procedure. The objective of this study was to characterize pathways through which bronchoscopists may be exposed to infectious agents during bronchoscopy procedures. Aerosol number concentrations (0.2-1 µm aerodynamic diameter) were measured using a P-Trak Ultrafine Particle Counter 8525 and mass concentrations (<10 µm) were measured using a SidePak Personal Aerosol Monitor AM510 near the head of patients during bronchoscopy procedures. Procedure pathway, number of patient coughs, number of suctioning events, number of contacts with different surfaces by the pulmonologist, and the use and doffing of personal protective equipment were recorded by the investigator on a specially designed form. Any pulmonologist performing a bronchoscopy procedure was eligible to participate. A total of 18 procedures were observed. Mean particle number and mass concentrations were not elevated during procedures relative to those measured before or after the procedure, on average, but the concentrations were highly variable, exhibiting high levels periodically. Patients frequently coughed during procedures (median 65 coughs, range: 0-565 coughs), and suctioning was commonly performed (median 6.5 suctioning events, range: 0-42). In all procedures, pulmonologists contacted the patient (mean 22.3 contacts, range: 1-48), bronchoscope (mean 19.4 contacts, range: 1-46), and at least one environmental surface (mean 31.2 contacts, range: 3-62). In the majority of procedures, the participant contacted his or her body or personal protective equipment (PPE), with a mean of 17.3 contacts (range: 4-48). More often than not, the observed PPE doffing practices differed from those recommended. Bronchoscopy procedures were associated with short-term increased ultrafine or respirable aerosol concentrations, and there were opportunities for contact transmission.

Bayesian Analysis of Occupational Exposure Data with Conjugate Priors.

Bayesian analysis is a flexible method that can yield insight into occupational exposures as the methods quantify plausible values for exposure parameters of interest, such as the mean, variance, and specific percentiles of the exposure distribution. We describe three Bayesian analysis methods for the analysis of normally distributed data (e.g. the logarithm of measurements of chemical hazards) that use conjugate prior distributions (normal for the mean, and inverse-χ2, inverse-Γ, or vague for the variance) to provide analytical expressions for the posterior distributions of the sufficient statistics of the normal distribution (e.g. the mean and variance). From these posterior distributions, the posterior distribution of any parameter of interest about the exposure distribution can be tabulated. The methods are illustrated using lead exposure data collected by the Occupational Safety and Health Administration at a copper foundry on multiple occasions. A unique feature of the normal-inverse-Γ method is that dependence of the mean and variance prior distributions is integrated out of the posterior distributions expressions, suggesting that a 'default' prior distribution on variance may be used: candidate default distributions are proposed based on the literature. Relative to other Bayesian analysis methods used in industrial hygiene, the methods described are flexible, and can be implemented without specialized software.

Arsenic in drinking water and prostate cancer in Illinois counties: An ecologic study.

BACKGROUND: Inorganic arsenic is a lung, bladder, and skin carcinogen. One of the major sources of exposure to arsenic is through naturally contaminated drinking water. While positive associations have been observed between arsenic in drinking water and prostate cancer, few studies have explored this association in the United States. OBJECTIVES: To evaluate the association between inorganic arsenic concentrations in community water systems and prostate cancer incidence in Illinois using an ecologic study design. METHODS: Illinois Environmental Protection Agency data on arsenic concentrations in drinking water from community water systems throughout the state were linked with county-level prostate cancer incidence data from 2007 to 2011 from the Illinois State Cancer Registry. Incidence rates were indirectly standardized by age to calculate standardized incidence ratios (SIRs) for each county. A Poisson regression model was used to model the association between county-level SIRs and mean arsenic tertile (0.33-0.72, 0.73-1.60, and 1.61-16.23ppb), adjusting for potential confounders. RESULTS: For counties with mean arsenic levels in the second tertile, the SIR was 1.05 (95% CI: 0.96-1.16). For counties with mean arsenic levels in the third tertile, the SIR was 1.10 (95% CI: 1.03-1.19). There was a significant linear dose-response relationship observed between mean arsenic levels and prostate cancer incidence (p for trend=0.003). CONCLUSIONS: In this ecologic study, counties with higher mean arsenic levels in community water systems had significantly higher prostate cancer incidence. Individual-level studies of prostate cancer incidence and low-level arsenic exposure are needed.

Cross-classified occupational exposure data.

We demonstrate the regression analysis of exposure determinants using cross-classified random effects in the context of lead exposures resulting from blasting surfaces in advance of painting. We had three specific objectives for analysis of the lead data, and observed: (1) high within-worker variability in personal lead exposures, explaining 79% of variability; (2) that the lead concentration outside of half-mask respirators was 2.4-fold higher than inside supplied-air blasting helmets, suggesting that the exposure reduction by blasting helmets may be lower than expected by the Assigned Protection Factor; and (3) that lead concentrations at fixed area locations in containment were not associated with personal lead exposures. In addition, we found that, on average, lead exposures among workers performing blasting and other activities was 40% lower than among workers performing only blasting. In the process of obtaining these analyses objectives, we determined that the data were non-hierarchical: repeated exposure measurements were collected for a worker while the worker was a member of several groups, or cross-classified among groups. Since the worker is a member of multiple groups, the exposure data do not adhere to the traditionally assumed hierarchical structure. Forcing a hierarchical structure on these data led to similar within-group and between-group variability, but decreased precision in the estimate of effect of work activity on lead exposure. We hope hygienists and exposure assessors will consider non-hierarchical models in the design and analysis of exposure assessments.

Cohort Study of Carbon Black Exposure and Risk of Malignant and Nonmalignant Respiratory Disease Mortality in the US Carbon Black Industry.

OBJECTIVE: To evaluate lung cancer and respiratory disease mortality associations with cumulative inhalable carbon black exposure among 6634 US carbon black workers. METHODS: This analysis was performed using standardized mortality ratio (SMRs) and Cox regression analyses. RESULTS: Lung cancer mortality was decreased overall (SMR = 0.77; 95% confidence interval [CI], 0.67 to 0.89) but less so among hourly male workers (SMR = 0.87; 95% CI, 0.71 to 1.05). No exposure-response association was observed with time-dependent cumulative inhalable carbon black: hazard ratio [HR] = 1.0 (95% CI, 0.6 to 1.6) for 20 to less than 50 mg/m·yr); HR = 1.3 (95% CI, 0.8 to 2.1) for 50 to less than 100 mg/m·yr; and HR = 1.4 (95% CI, 0.9 to 2.1) for 100 mg/m·yr or more compared with referent (<20 mg/m·yr). No consistent associations were observed between cumulative inhalable carbon black exposure and respiratory disease mortality. CONCLUSION: Quantitative carbon black exposure estimates were not related to lung cancer or nonmalignant respiratory disease mortality.

Water quality as a predictor of gastrointestinal illness following incidental contact water recreation.

Microbial measures of water quality are predictors of gastrointestinal illness among swimmers in some settings but not in others. Little is known whether water quality measures predict illness among people who engage in popular water recreation activities such as paddling, rowing, fishing, or boating ("incidental contact water recreation"). We sought to evaluate indicator microbes, protozoan pathogens, and turbidity as predictors of gastrointestinal illness following incidental contact water recreation. A cohort study of incidental contact water recreation was conducted in the Chicago, USA area. Recreation took place on inland lakes, rivers, Lake Michigan, and an urban waterway heavily impacted by wastewater effluent. Water samples were analyzed for Escherichia coli, enterococci, somatic coliphages, F+ coliphages, Giardia spp. and Cryptosporidium spp. (oo)cysts, and for turbidity. Median enterococci concentrations were 71.0 and 199.8 colony forming units/100  mL at general use and effluent-dominated waters, respectively. Among 4694 study participants with complete covariate data, 193 (4.1%) developed gastrointestinal illness within three days of water recreation. In multivariable logistic regression analysis, water quality metrics did not predict gastrointestinal illness among water recreators. Several variables other than water quality were associated acute gastrointestinal illness. The odds of such illness was increased by approximately two-fold by the presence of a chronic gastrointestinal condition, water exposure to the face, and by approximately 50% among those who fished (as opposed to other incidental contact activities). The odds of illness were reduced by approximately 50% among individuals who frequently used a water body for recreation. Unlike studies of swimmers at wastewater-impacted beaches that observed associations between water quality and illness incidence, this study did not. Public health protections for incidental contact recreation might focus on reducing exposure, particularly among fishers, those with chronic gastrointestinal conditions, and new recreators.

Exposure Reconstruction and Risk Analysis for Six Semiconductor Workers With Lymphohematopoietic Cancers.

OBJECTIVE: To investigate whether workplace exposures to recognized lymphohematopoietic carcinogens were possibly related to cancers in six semiconductor-manufacturing workers. METHODS: A job-exposure matrix was developed for chemical and physical process agents and anticipated by-products. Potential cumulative occupational exposures of the six cases were reconstructed. The role of workplace exposures in cancer was evaluated through quantitative risk assessment and by comparison with epidemiological literature. RESULTS: Two workers were potentially exposed to agents capable of causing their diagnosed cancers. Reconstructed exposures were similar to levels in outdoor environments and lower than exposures associated with increased risks in epidemiological studies. Cancer risks were estimated to be less than 1 in 10,000 persons. CONCLUSIONS: The development of cancer among the six workers was unlikely to be explained by occupational exposures to recognized lymphohematopoietic carcinogens.

Application of a two-zone model to estimate medical laser-generated particulate matter exposures.

We estimated particulate matter exposures for two simulated medical laser procedures using a near-field/far-field model. Size-specific mass emission rates obtained from a laboratory-based emission chamber study were used with estimated room size, air exchange rate, and interflow between zones to demonstrate the potential exposure range. Modeled steady-state concentrations for the near-field ranged between 80 and 2140 µg/m(3) and between 40 and 1650 µg/m(3) in the far-field. Results indicate concentrations in the simulated scenarios are similar to those obtained from limited field assessments conducted in hospital operating rooms. Since new medical laser technologies and applications continue to grow, modeled occupational exposures of medical laser-generated particulate matter can be useful in better understanding these exposures in the clinical environment, and to inform control strategies.

A study of adverse birth outcomes and agricultural land use practices in Missouri.

BACKGROUND: Missouri is an agriculturally intensive state, primarily growing corn and soybeans with additional rice and cotton farming in some southeastern counties. Communities located in close proximity to pesticide-treated fields are known to have increased exposure to pesticides and may be at increased risk of adverse birth outcomes. The study aims were to assess the relationship between county-level measures of crop-specific agricultural production and adverse birth outcomes in Missouri and to evaluate the most appropriate statistical methodologies for doing so. METHODS: Potential associations between county level data on the densities of particular crops and low birth weight and preterm births were examined in Missouri between 2004-2006. Covariates considered as potential confounders and effect modifiers included gender, maternal race/ethnicity, maternal age at delivery, maternal smoking, access to prenatal care, quarter of birth, county median household income, and population density. These data were analyzed using both standard Poisson regression models as well as models allowing for temporal and spatial correlation of the data. RESULTS: There was no evidence of an association between corn, soybean, or wheat densities with low birth weight or preterm births. Significant positive associations between both rice and cotton density were observed with both low birth weight and preterm births. Model results were consistent using Poisson and alternative models accounting for spatial and temporal variability. CONCLUSIONS: The associations of rice and cotton with low birth weight and preterm births warrant further investigation. Study limitations include the ecological study design and limited available covariate information.

Modeled occupational exposures to gas-phase medical laser-generated air contaminants.

Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.

Benzene exposure and risk of non-Hodgkin lymphoma.

Exposure to benzene, an important industrial chemical and component of gasoline, is a widely recognized cause of leukemia, but its association with non-Hodgkin lymphoma (NHL) is less clear. To clarify this issue, we undertook a systematic review of all case-control and cohort studies that identified probable occupational exposures to benzene and NHL morbidity or mortality. We identified 43 case-control studies of NHL outcomes that recognized persons with probable occupational exposure to benzene. Forty of these 43 (93%) studies show some elevation of NHL risk, with 23 of 43 (53%) studies finding statistically significant associations between NHL risk and probable benzene exposure. We also identified 26 studies of petroleum refinery workers reporting morbidity or mortality for lymphomas and all neoplasms and found that in 23 (88%), the rate of lymphoma morbidity or mortality was higher than that for all neoplasms. A substantial healthy-worker effect was evident in many of the studies and a comprehensive reevaluation of these studies with appropriate adjustments should be undertaken. Numerous studies have also reported associations between benzene exposure and the induction of lymphomas in mice. Further, because benzene is similar to alkylating drugs and radiation in producing leukemia, it is plausible that it might also produce lymphoma as they do and by similar mechanisms. Potential mechanisms include immunotoxicity and the induction of double-strand breaks with subsequent chromosome damage resulting in translocations and deletions. We conclude that, overall, the evidence supports an association between occupational benzene exposure and NHL.