Occupational Epidemiological Studies Research Articles

Development of a job-exposure matrix-like exposure assessment method for the US general population based on Occupational Information Network (O*NET) job tasks.

Job-exposure matrices (JEMs) are often used for exposure assessment in occupational exposure and epidemiology studies. However, general population JEMs are difficult to find and access for workers in the United States of America. We aimed to use publicly available information to develop a JEM-like exposure assessment method to determine exposure to a wide range of occupational agents in a wide range of occupations for US general population studies. We used information from the US Department of Labor's Occupational Information Network database (O*NET) for 19,636 job tasks and 974 civilian occupations. We used automated keyword searches to identify 1,804 job tasks that involved exposure to 50 occupational agents. We had 2 reviewers determine whether each identified job task actually involved exposure to the 50 occupational agents. We had a third reviewer, a certified industrial hygienist, assess any job task and exposure for which the first 2 reviewers disagreed. For each U.S. Census 2010 occupation code, we used this information to derive 3 exposure variables for each occupational agent: ever exposure, number of job tasks of exposure, and frequency of exposure. Our keyword searches identified a median of 10 (interquartile range [IQR]: 43.75) job tasks for each occupational agent, and the maximum was 308. We determined job tasks actually involved exposure to 45 occupational agents, including solvents, air pollution, pesticides, radiation, metals, etc. We derived the 3 exposure variables for these 45 occupational agents for 516 U.S. Census 2010 occupation codes. The median percentage for ever exposure to individual occupational agents was 1.16% (IQR: 1.74%), and the maximum was 11.43%. Our JEM-like exposure assessment method based on O*NET information can be used to determine exposure to a wide range of occupational agents in a wide range of occupations for the US general population.

Application of artificial intelligence algorithms and low-cost sensors to estimate respirable dust in the workplace

The Internet of Things (IoT) and low-cost sensor technology have become common tools for environmental exposure monitoring; however, their application in measuring respirable dust (RD) in the workplace remains limited. This study aimed to develop a predictive model for RD using artificial intelligence (AI) algorithms and low-cost sensors and subsequently assess its validity using a standard sampling approach. Various low-cost sensors were combined into an RD sensor module and mounted on a portable aerosol monitor (GRIMM 11-D) for two weeks. AI algorithms were used to capture data per minute over 14 days to establish predictive RD models. The best-fitting model was validated using an aluminum cyclone equipped with an air pump and polytetrafluoroethylene filters to sample the 8-hour RD for 5 days at an aircraft manufacturing company. This module was continuously monitored for two weeks to evaluate its stability. The RD concentration measured by GRIMM 11-D in a general outdoor environment over two weeks was 28.1 ± 16.1 μg/m3 (range: 2.4–85.3 μg/m3). Among the various established models, random forest regression was observed to have the best prediction capacity (R2 = 0.97 and root mean square error = 2.82 μg/m3) in comparison to the other 19 methods. Field-based validation revealed that the predicted RD concentration (35.9 ± 4.1 μg/m3, range: 32.7–42.9 μg/m3) closely approximated the results obtained by the traditional method (38.1 ± 8.9 μg/m3, range: 28.1–52.5 μg/m3), and a strong positive Spearman correlation was observed between the two (rs = 0.70). The average bias was −2.2 μg/m3 and the precision was 5.8 μg/m3, resulting in an accuracy of 6.2 μg/m3 (94.2 %). Data completeness was 99.7 % during the continuous two-week monitoring period. The developed sensor module of RD exhibited excellent predictive performance and good data stability that can be applied to exposure assessments in occupational epidemiological studies.

Estudos epidemiológicos ocupacionais em área rural: desafios metodológicos

Abstract Introduction: agricultural production in Brazil has grown in recent decades, and rural workers are exposed to many occupational risks. Epidemiological studies on the topic remain limited, especially regarding methodological complexity. Objectives: to present the main methodological challenges to carrying out occupational epidemiological studies in rural areas. Methods: the considerations presented in this article are based on the literature and on the experience of the authors as researchers of this thematic. Results: we approached concepts about target population, living and working place, workers classification, and agricultural production context characterization. We discussed sampling strategies, characterization of economic indicators, including agricultural production and mechanization level, pesticide exposure, such as chemical types, forms, and frequency of exposure, pesticide poisonings, and availability and use of personal protective equipment. We described the necessary care with biological samples and aspects involving interviewers, training, field work, and clinical and logistical issues. Conclusion: despite the methodological and logistical challenges, adequate planning enables successful research studies, of great complexity and high scientific level, about the health-work relationship in agricultural activity.

Agreement between an expert-rated mini job exposure matrix of occupational biomechanical exposures to the lower body and technical measurements or observation: a method comparison study

ObjectivesInvestigating the agreement between an expert-rated mini job exposure matrix (JEM) of lower body exposures and technical measurements of worktime spent standing/walking and observation-based estimates of time spent kneeling/squatting and...

Health hazards resulting from occupational exposure to enfluran - overview of tests and analysis of admissible concentration values

The aim of this work is to analyze the health hazards of enflurane exposure and to analyze the occupational exposure limits (OEL). The method of obtaining evidence based on a review of online databases of scientific journals was used. Enflurane is an inhalation anesthetic. Malignant hyperthermia, seizures, arrhythmias, respiratory depression and hypotension have been observed in patients. Occupational exposure to enflurane may occur in healthcare professionals. The target organ for enflurane is the central nervous system with a critical consequence of deterioration in psychomotor performance. In studies on volunteers recruited from the medical staff of operating rooms exposed to enflurane, a significant deterioration in the results of the Simple Reaction Time Test was shown. World experts' groups assume that the LOAEC (lowest observed adverse effect concentration) value for the deterioration of psychomotor test results is 5-10% of the MAC value (minimal anesthetic concentration), i.e., 6342-12 684 mg/m3. Assessment of the nephrotoxic potential of enflurane has shown that it is unlikely to occur because biotransformation of enflurane in humans results in a low peak serum fluoride concentration of 15 μmol/l. Early reports about liver damage in patients were not be supported. Occupational exposure epidemiological studies have raised concerns about the effects of anesthetic gas mixtures on the abortion rate or on fetal development and birth defects in children, but none of these studies specifically determined the type and concentration of anesthetic gases used. The carcinogenicity and mutagenicity studies were negative. Occupational exposure to enflurane is not monitored in Poland, as no standard value has been established for it in the air of the working environment. It is necessary to quickly introduce this anesthetic along with the applicable limit value to the OEL list. Med Pr. 2022;73(1):51-69.

Occupational Exposure Assessment Tools in Europe: A Comprehensive Inventory Overview.

ObjectivesThe Network on the Coordination and Harmonisation of European Occupational Cohorts (OMEGA-NET) was set up to enable optimization of the use of industrial and general population cohorts across Europe to advance aetiological research. High-quality harmonized exposure assessment is crucial to derive comparable results and to enable pooled analyses. To facilitate a harmonized research strategy, a concerted effort is needed to catalogue available occupational exposure information. We here aim to provide a first comprehensive overview of exposure assessment tools that could be used for occupational epidemiological studies.MethodsAn online inventory was set up to collect meta-data on exposure assessment tools. Occupational health researchers were invited via newsletters, editorials, and individual e-mails to provide details of job-exposure matrices (JEMs), exposure databases, and occupational coding systems and their associated crosswalks to translate codes between different systems, with a focus on Europe.ResultsMeta-data on 36 general population JEMs, 11 exposure databases, and 29 occupational coding systems from more than 10 countries have been collected up to August 2021. A wide variety of exposures were covered in the JEMs on which data were entered, with dusts and fibres (in 14 JEMs) being the most common types. Fewer JEMs covered organization of work (5) and biological factors (4). Dusts and fibres were also the most common exposures included in the databases (7 out of 11), followed by solvents and pesticides (both in 6 databases).ConclusionsThis inventory forms the basis for a searchable web-based database of meta-data on existing occupational exposure information, to support researchers in finding the available tools for assessing occupational exposures in their cohorts, and future efforts for harmonization of exposure assessment. This inventory remains open for further additions, to enlarge its coverage and include newly developed tools.

Impact of Variability in Job Coding on Reliability in Exposure Estimates Obtained via a Job-Exposure Matrix.

The use of a job-exposure matrix (JEM) to assess exposure to potential health hazards in occupational epidemiological studies requires coding each participant's job history to a standard occupation and/or industry classification system recognized by the JEM. The objectives of this study were to assess the impact of inter-coder variability in job coding on reliability in exposure estimates derived from linking the job codes to the Canadian job-exposure matrix (CANJEM) and to identify influent parameters. Two trained coders independently coded 1000 jobs sampled from a population-based case-control study to the ISCO-1968 occupation classification at the five-digit resolution level, of which 859 could be linked to CANJEM using both assigned codes. Each of the two sets of codes was separately linked to CANJEM and thereby generated, for each of the 258 occupational agents available in CANJEM, two exposure estimates: exposure status (yes/no) and intensity of exposure (low, medium, and high) for exposed jobs only. Then, inter-rater reliability (IRR) was computed (i) after stratifying agents in 4 classes depending, for each, on the proportion of occupation codes in CANJEM defined as 'exposed' and (ii) for two additional scenarios restricted to jobs coded differently: the first one using experts' codes, the other one using codes randomly selected. IRR was computed using Cohen's kappa, PABAK and Gwet's AC1 index for exposure status, and weighted kappa and Gwet's AC2 for exposure intensity. Across all agents and based on all jobs, median (Q1, Q3; Nagents) values were 0.68 (0.59, 0.75; 220) for kappa, 0.99 (0.95, 1.00; 258) for PABAK, and 0.99 (0.97, 1.00; 258) for AC1. For the additional scenarios, median kappa was 0.28 (0.00, 0.45; 209) and -0.01 (-0.02, 00; 233) restricted to jobs coded differently using experts' and random codes, respectively. A similar decreasing pattern was observed for PABAK and AC1 albeit with higher absolute values. Median kappa remained stable across exposure prevalence classes but was more variable for low prevalent agents. PABAK and AC1 decreased with increasing prevalence. Considering exposure intensity and all exposed jobs, median values were 0.79 (0.68, 0.91; 96) for weighted kappa, and 0.95 (0.89, 0.99; 102) for AC2. For the additional scenarios, median kappa was, respectively, 0.28 (-0.04, 0.42) and -0.05 (-0.18, 0.09) restricted to jobs coded differently using experts' and random codes, with a similar though attenuated pattern for AC2. Despite reassuring overall reliability results, our study clearly demonstrated the loss of information associated with jobs coded differently. Especially, in cases of low exposure prevalence, efforts should be made to reliably code potentially exposed jobs.

Assessment of the Oxidative Potential and Oxidative Burden from Occupational Exposures to Particulate Matter.

Oxidative potential (OP) is a toxicologically relevant metric that integrates features like mass concentration and chemical composition of particulate matter (PM). Although it has been extensively explored as a metric for the characterization of environmental particles, this is still an underexplored application in the occupational field. This study aimed to estimate the OP of particles in two occupational settings from a construction trades school. This characterization also includes the comparison between activities, sampling strategies, and size fractions. Particulate mass concentrations (PM4-Personal, PM4-Area, and PM2.5-Area) and number concentrations were measured during three weeks of welding and construction/bricklaying activities. The OP was assessed by the ascorbate assay (OPAA) using a synthetic respiratory tract lining fluid (RTLF), while the oxidative burden (OBAA) was determined by multiplying the OPAA values with PM concentrations. Median (25th-75th percentiles) of PM mass and number concentrations were 900 (672-1730) µg m-3 and 128 000 (78 000-169 000) particles cm-3 for welding, and 432 (345-530) µg m-3 and 2800 (1700-4400) particles cm-3 for construction. Welding particles, especially from the first week of activities, were also associated with higher redox activity (OPAA: 3.3 (2.3-4.6) ρmol min-1 µg-1; OBAA: 1750 (893-4560) ρmol min-1 m-3) compared to the construction site (OPAA: 1.4 (1.0-1.8) ρmol min-1 µg-1; OBAA: 486 (341-695) ρmol min-1 m-3). The OPAA was independent of the sampling strategy or size fraction. However, driven by the higher PM concentrations, the OBAA from personal samples was higher compared to area samples in the welding shop, suggesting an influence of the sampling strategy on PM concentrations and OBAA. These results demonstrate that important levels of OPAA can be found in occupational settings, especially during welding activities. Furthermore, the OBAA found in both workplaces largely exceeded the levels found in environmental studies. Therefore, measures of OP and OB could be further explored as metrics for exposure assessment to occupational PM, as well as for associations with cardiorespiratory outcomes in future occupational epidemiological studies.

Occupational Exposure to Carcinogens and Occupational Epidemiological Cancer Studies in Iran: A Review.

Simple SummaryOccupational cancers can be prevented by eliminating hazardous substances or by reducing workers’ exposures. Characterizing the extent of exposure to carcinogens in workplaces and industries is a crucial first step to exposure control. Iran is one of the most industrialized countries in the Middle East, yet lacks an overview of the extent of exposure to carcinogens and comprehensive risk management. This review provides an overview of studies conducted to date and demonstrates the need for interdisciplinary collaboration to inform occupational research and exposure control in Iran and beyond. Introduction: The extent of exposure to occupational carcinogens is not well characterized in Iran, and little is known about the burden of occupational cancer. Objectives: This study aimed to describe exposure to occupational carcinogens and occupational epidemiology studies in Iran. Methods: Relevant studies up to January 2021 in Iran were identified through three databases (PubMed, Web of Science, and Google Scholar). Results: Forty-nine publications from 2009 to 2020 (one cohort, 11 case-control, 34 exposure monitoring studies, and three cancer burden studies) were included. The exposure monitoring studies were conducted mainly in the petroleum industry, metal industry, manufacturing of electronics, manufacturing of plastics, construction industry, and service industry. A few of the case-control studies also reported increased risk of cancers in relation to work in those industries. Conclusions: Occupational cancer epidemiology in Iran is at an early stage. Both epidemiological and exposure monitoring studies are generally limited in size to provide robust evidence of occupational cancer risks. A coherent strategy to estimate the occupational cancer burden in Iran should start with conducting epidemiological studies along with systematic monitoring of occupational carcinogens for use in hazard control and research.

Novel insights into cytochrome P450 enzyme and solute carrier families in cadmium-induced liver injury of pigs

Cadmium (Cd) is a typical pollutant and carcinogen in environment. Exposure assessment of contaminants is an important component of occupational and environmental epidemiological studies. Early studies of Cd have focused on aquatic animals, chickens and rats. However, toxicological evaluation of Cd in pigs has not been reported. Therefore, twelve pigs were randomly divided into two groups (n = 6): the control group and the Cd group (Cd content: 15 ± 0.242 mg/kg feed) in this study, the experimental period was 30 d, and the toxic effects of Cd on the liver of weanling piglets were examined by antioxidant function, liver function, Cd content, histological examination and transcriptomics. The results showed that the changes of antioxidant function, liver function and Cd content were significant in the liver. Transcriptional profiling results showed that 399 differentially expressed genes (DEGs) were significantly up-regulated while 369 DEGs were remarkably down-regulated in Cd group, and which were concentrated in three ontologies: molecular function, cellular component and biological processes. Interestingly, significant changes in some genes of the cytochrome P450 enzyme (CYP450) and solute carrier (SLC) families have been observed and were consistent with qRT-PCR results. In conclusion, Cd could cause liver injury in weanling piglets and change the transcriptomic characteristics of liver. CYP450 and SLC families play an indispensable role in Cd-mediated hepatotoxicity. Importantly, changes in mRNA levels of CYP2B22, CYP7A1, CYP8B1, SLC26A8, SLC11A1, SLC27A2 and SLC22A7 induced by Cd have been reported for the first time. Our findings will provide a new insight for better assessing the mechanism of Cd toxicity to the liver.

Occupational Contact Dermatitis in Employees of Large-Scale Narcotic Crop Farms of Ethiopia: Prevalence and Risk Factors. A Self-Reported Study Using the Nordic Occupational Skin Questionnaire.

Background:Occupational skin diseases are the second leading occupational disease, accounting for almost 25% of all missed workdays. Occupational contact dermatitis (OCD) accounts for 70% to 90% of all skin disorders in the workplace. Only a few occupational epidemiology studies have looked into the prevalence and risk factors of occupation-induced dermatitis among narcotic crop farm workers around the world. Related studies in Ethiopia are even fewer.Methods:A cross-sectional survey was conducted in the Dirashe district of Southern Ethiopia from March 23 to April 12, 2021. Data was collected using a standardized interviewer-administered questionnaire. The history of contact dermatitis was determined using the standardized Nordic Occupational Skin Questionnaire version 2002 (NOSQ-2002). A total of 578 farm laborers took part in the study, which was conducted using a systematic random sampling. Descriptive statistics and multivariable regression were used to characterize the data and identify factors associated with occupational contact dermatitis.Result:The prevalence of self-reported occupational contact dermatitis in the past 12 months among workers of large-scale Khat farms was (AOR: 67.80%, 95% CI [61.00, 76.23]). In the multivariable regression, being older (AOR: 5.51, 95% CI [1.79, 7.24]), working as a bundle binder (AOR: 5.74, 95% CI [2.12, 15.55]), not wearing personal protective equipment (PPE) (AOR: 2.50, 95% CI [1.64, 3.81]), and having poor knowledge of pesticides use, storage, and disposal methods (AOR: 2.50, 95% CI [1.64, 3.81]) were associated with occupational contact dermatitis.Conclusion:Contact dermatitis caused by work is very common among Khat farm laborers. Measures to promote safe practices and reduce exposure to hazards, such as removing expired and/or banned chemicals, purchasing alternative pesticides that meet legislative requirements, job rotation and routine training of staff on safe practices, increasing safety signage, and performing risk assessments, as well as improving the quantity and quality of institutional protective equipment supplies may thus contribute to the enhancement of safe work practices.

Association of low blood arsenic exposure with level of malondialdehyde among Chinese adults aged 65 and older

High environmental arsenic exposure can increase chronic oxidative stress in experimental studies and in occupational epidemiology studies. Many regulatory agencies have put forth arsenic exposure limits, it is still unclear that whether low environmental arsenic exposure was associated with adverse health outcome in general population. This study aimed to explore the association of low blood arsenic with malondialdehyde in community-dwelling older adults. We used a cross-sectional study of 2384 older adult individuals aged ≥65 years (mean age: 85 years) from the Healthy Aging and Biomarkers Cohort Study in 2017. The median blood arsenic level was 1.41 μg/L. High oxidative stress was categorized according to the 95th percentile of MDA levels (7.47 nmol/mL). Restricted cubic spline models showed that blood arsenic levels were positively associated with malondialdehyde levels (P < 0.01); and the risk of high oxidative stress was no longer significantly increased when blood arsenic level up to 8.74 μg/L. After adjusting for potential confounders, the odds ratios of high oxidative stress for the second, third, and fourth quartiles of blood arsenic were 2.35 (1.11–4.96), 3.87 (1.90–7.91), and 4.18 (2.00–8.72) (Ptrend < 0.01), compared with the first quartile. We concluded that even low arsenic exposure was associated with higher risk of oxidative stress, in a nonlinear dose-response.

Development of Job Exposure Matrices to Estimate Occupational Exposure to Solar and Artificial Ultraviolet Radiation.

Job exposure matrices (JEMs) are important tools for estimating occupational exposures in study populations where only information on industry and occupation (I&O) are available. JEMs The objective of this work was to create JEMs for solar and artificial ultraviolet radiation (UVR) using a US standardized coding scheme. Using U.S. Census Bureau industry and occupation codes, separate lists of I&O pairs were developed for solar and artificial UVR by a panel of Certified Industrial Hygienists who assigned exposure ratings to I&O pairs with potential exposure. Parameters for exposure included prevalence (P) and frequency (F) for solar UVR and P, F, and intensity (I) for artificial UVR. Prevalence, or percent of all workers employed in an I&O pair who were exposed, was categorically rated: 0 to <1, 1 to <20; 20 to <80, and ≥80. Frequency of exposure, defined by the number of hours per week workers were exposed, was categorically rated: 0 to <5, 5 to <20, 20 to <35, and ≥35 h per week. For artificial UVR only, intensity of exposure was assigned three ratings: low, low with rare excursions, and >low under normal conditions. Discrepant ratings were resolved via consensus. After excluding I&O pairs assigned P and F ratings of 0 (solar UVR) and P, F, and I ratings of 0 (artificial UVR) from the JEM, 9206 I&O pairs were rated for solar UVR and 2010 I&O pairs for artificial UVR. For solar UVR, 723 (7.9% of all rated pairs) had ratings in the highest category for P and F; this group included 45 occupations in varied industries. Construction and extraction occupations represented most of the occupations (n = 20; 44%), followed by farming, fishing, and forestry occupations (n = 6; 13%). For artificial UVR, 87 I&O pairs (4.3% of all rated pairs) had maximum ratings for P, F, and I; these comprised a single occupation (welding, soldering, and brazing workers) in diverse industries. JEMs for solar and artificial UVR were developed for a broad range of I&O pairs in the US population and are available for use by researchers conducting occupational epidemiological studies.

Abstract IA10: Neighborhood matters: Residential levels of air toxics and increased risk of early childhood acute lymphocytic leukemia

Abstract Background: The evidence of benzene and 1,3-butadiene as leukemogens in adults comes primarily from occupational epidemiologic studies. The major environmental sources of benzene and 1,3-butadiene, which are classified as hazardous air pollutants by the U.S. Environmental Protection Agency (EPA), include vehicular exhaust and emissions from industrial facilities. Exposures to these pollutants during in utero and early life may play an etiologic role in childhood leukemia. Hence, we conducted a population-based case-control study (Symanski et al., Environmental Health 2016;15:70) to examine the role of residential levels of benzene and 1,3-butadiene in early childhood leukemia in a state that has an abundant number of petrochemical plants and extensive road traffic in and around urban areas. Methods: We identified cases of acute lymphocytic leukemia (ALL) diagnosed in children under age 5 years from the Texas Cancer Registry for the years 1995-2011 and linked cancer registry data, where possible, to birth records in the state. Using Texas birth certificates, we selected 10 controls per case, frequency matching by birth month and year to allow for the same potential for exposure. Geocoded maternal addresses at delivery were linked to the U.S. EPA’s National-Scale Air Toxics Assessment modeled census-tract level estimates of benzene and 1,3-butadiene in ambient air. We evaluated maternal and infant characteristics that were available from birth certificates, along with neighborhood-level metrics of disadvantage, as potential confounders. We applied mixed-effects logistic regression models to evaluate associations between air pollutants and childhood leukemia in single and copollutant models. Results: In single-pollutant models, adjusted odds ratios were elevated for infants whose mothers lived in census tracts with higher benzene and 1,3-butadiene levels. In adjusted models that included benzene and 1,3-butadiene together, odds of ALL remained elevated for 1,3-butadiene (medium-exposure group: OR=1.22, 95% CI: 1.00-1.50; medium-high group: OR=1.28, 95% CI: 1.01-1.63; and high-exposure group: OR=1.40, 95% CI: 1.06-1.86) relative to the low-exposure group. In contrast, results were close to the null value for benzene in all exposure groups. Conclusions: Studies are needed to confirm our finding that early life environmental exposure to 1,3-butadiene (and not benzene) increases risk of ALL in young children. Our results add to the growing literature that health disparities arise, in part, because air quality varies depending on where individuals live. Citation Format: Elaine Symanski, P. Grace Tee Lewis, Ting-Yu Chen, Wenyaw Chan, Dejian Lan, Xiaomei Ma. Neighborhood matters: Residential levels of air toxics and increased risk of early childhood acute lymphocytic leukemia [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr IA10.

Objective Measurement of Carcinogens Among Dominican Republic Firefighters Using Silicone-Based Wristbands

PURPOSE Firefighters around the world are exposed to physical hazards and toxic chemical agents during fire incident response. Occupational epidemiologic studies of the firefighter workforce have documented an excess cancer risk for brain, digestive, genitourinary, and lymphohematopoietic organs compared with the general population. Despite the elevated cancer risk, little is known about what specific types of carcinogenic chemicals first responders encounter during a typical work shift, particularly in low-resources settings, like the Dominican Republic. This pilot study characterizes objective measurements of carcinogenic exposure using passive sampling silicone-based wristbands among Dominican firefighters. METHODS Firefighters from a metropolitan fire service in the Dominican Republic were asked to wear a silicone-based wristband during one typical 24-hour shift. A pre- and postshift survey was administered to the firefighter to assess their self-reported sociodemographic, employment, and work shift characteristics. Wristbands were collected after their 24-hour shift and processed for the type and quantity of polycyclic aromatic hydrocarbons (PAHs), a family of known carcinogenic compounds, to which firefighters were exposed. RESULTS Among 15 firefighters who wore a wristband during their 24-hour shift, 73.3% responded to a fire with an average of 3.7 calls during the shift. Fire incident responses included structural fires (54.5%), outside and other fires (36.4%), and vehicle fires (9.1%). Total PAH exposure was significantly higher among Dominican firefighters who responded to a fire compared with firefighters with no fire during their shift (261 parts per billion [ppb] v 117 ppb, respectively; P = .003). Among the 19 PAHs quantified, low-molecular-weight phenanthrene was present in the highest concentration (32 ppb) among firefighters not responding to fires. CONCLUSION Passive objective sampling of PAHs using silicone-based wristbands among Dominican firefighters showed direct exposure to carcinogenic compounds during a typical 24-hour firefighter shift. Firefighters not attending a fire had lower levels of PAHs, suggesting carcinogenic contaminants are present at the fire station.

Developing a Job Exposure Matrix of Work Organization Hazards in the United States: A Review on Methodological Issues and Research Protocol.

BackgroundMost job exposure matrices (JEMs) have been developed for chemical and physical hazards in the United States (US). In addition, the overall validity of most JEMs of work organization hazards using self-reported data in the literature remains to be further tested due to several methodological weaknesses.MethodsThis paper aims to review important methodological issues with regard to a JEM of work organization hazards using self-report data and to present a research protocol for developing a four-axis (job titles, hazards, sex, and time) JEM of major work organization hazards using the US General Social Survey-Quality of Work-Life (GSS-QWL) data (2002–2018; N = 7,100 workers).ResultsFive methodological weaknesses in existing JEMs of work organization hazards using self-report data were identified: having only two axes (hazard and occupation), using psychometrically weak items and scales, including scales having little interoccupational variability, unresolved optimal minimum numbers of subjects per occupation, and low accessibility. The methodological weaknesses were successfully addressed in the proposed research protocol.ConclusionThe work organization JEM to be developed will significantly facilitate and strengthen occupational epidemiological studies on work organization hazards and major health outcomes, improve national and occupational surveillance of work organization hazards, and promote interventions for a healthy work environment in the US.

Challenges and recommendations on the conduct of systematic reviews of observational epidemiologic studies in environmental and occupational health.

Systematic reviews are powerful tools for drawing causal inference for evidence-based decision-making. Published systematic reviews and meta-analyses of environmental and occupational epidemiology studies have increased dramatically in recent years; however, the quality and utility of published reviews are variable. Most methodologies were adapted from clinical epidemiology and have not been adequately modified to evaluate and integrate evidence from observational epidemiology studies assessing environmental and occupational hazards, especially in evaluating the quality of exposure assessments. Although many reviews conduct a systematic and transparent assessment for the potential for bias, they are often deficient in subsequently integrating across a body of evidence. A cohesive review considers the impact of the direction and magnitude of potential biases on the results, systematically evaluates important scientific issues such as study sensitivity and effect modifiers, identifies how different studies complement each other, and assesses other potential sources of heterogeneity. Given these challenges of conducting informative systematic reviews of observational studies, we provide a series of specific recommendations based on practical examples for cohesive evidence integration to reach an overall conclusion on a body of evidence to better support policy making in public health.

Trichloroethylene, a ubiquitous environmental contaminant in the risk for Parkinson's disease.

Organic solvents are common chemicals used in industry throughout the world, however, there is evidence for adverse health effects from exposure to these compounds. Trichloroethylene (TCE) is a halogenated solvent that has been used as a degreasing agent since the early 20th century. Due to its widespread use, TCE remains one of the most significant environmental contaminants in the US, and extensive research suggests TCE is a causative factor in a number of diseases, including cancer, fetal cardiac development, and neurotoxicity. TCE has also been implicated as a possible risk factor in the development of the most common neurodegenerative movement disorder, Parkinson's disease (PD). However, there is variable concordance across multiple occupational epidemiological studies assessing TCE (or solvent) exposure and risk for PD. In addition, there remains a degree of uncertainty about how TCE elicits toxicity to the dopaminergic system. To this end, we review the specific neurotoxic mechanisms of TCE in the context of selective vulnerability of dopaminergic neurons. In addition, we consider the complexity of combined risk factors that ultimately contribute to neurodegeneration and discuss the limitations of single-factor exposure assessments.

Longitudinal follow-up of health effects among workers handling engineered nanomaterials: a panel study

BackgroundAlthough no human illness to date is confirmed to be attributed to engineered nanoparticles, occupational epidemiological studies are needed to verify the health effects of nanoparticles. This study used a repeated measures design to explore the potential adverse health effects of workers handling nanomaterials.MethodsStudy population was 206 nanomaterial-handling workers and 108 unexposed controls, who were recruited from 14 nanotechnology plants. They were followed up no less than two times in four years. A questionnaire was used to collect potential confounders and detailed work conditions. Control banding was adopted to categorize risk level for each participant as a surrogate marker of exposure. Health hazard markers include cardiopulmonary dysfunction markers, inflammation and oxidative damage markers, antioxidant enzymes activity, and genotoxicity markers. The Generalized Estimating Equation model was applied to analyze repeated measurements.ResultsIn comparison to the controls, a significant dose-dependent increase on risk levels for the change of superoxide dismutase (p<0.01) and a significant increase of glutathione peroxidase change in risk level 1 was found for nanomaterial-handling workers. However, the change of cardiovascular dysfunction, lung damages, inflammation, oxidative damages, neurobehavioral and genotoxic markers were not found to be significantly associated with nanomaterials handling in this panel study.ConclusionsThis repeated measurement study suggests that there was no evidence of potential adverse health effects under the existing workplace exposure levels among nanomaterials handling workers, except for the increase of antioxidant enzymes.

Influence of errors in job codes on job exposure matrix-based exposure assessment in the register-based occupational cohort DOC*X.

Objective Job-exposure matrices (JEM) may be efficient for exposure assessment in occupational epidemiological studies, but they rely on valid job information. We evaluated the agreement between JEM-based exposure estimates according to self-reported job titles converted to DISCO-88 codes and according to register-based DISCO-88 codes in the Danish Occupational Cohort with eXposure data (DOC*X). Furthermore, we evaluated the agreement between these two sets of DISCO-88 codes. Methods We used JEM regarding wood dust, lifting, standing/walking, arm elevation >90°, and noise from DOC*X. Participants from previous questionnaire studies were assigned JEM-based exposure estimates using (i) self-reported job titles converted to DISCO-88 codes and (ii) DISCO-88 codes registered in DOC*X, in four time periods (1976-78: N=7707; 1981-83: N=2193; 1991-94: N=2664; 2004: N=11 782). Agreement between the exposure estimates and between the DISCO-88 codes (four-digit levels, 1-4) was evaluated by kappa (κ) statistics. Sensitivities were calculated using the self-reported observation as the gold standard. Results We found substantial agreement (κ>0.60) between exposure estimates for all types of job-exposures and all time periods except for one κ. Low sensitivity (30-65%) was found for the period 1981-83, but for the other time periods the sensitivities varied between 60-91%. For individual 4-digit DISCO-88 codes, the sensitivities varied substantially and overall the sensitivities increased by lower digit level of DISCO-88. Conclusion The validity of the DISCO-88 codes in DOC*X was generally high. Substantial agreement was found for the JEM-based exposure estimates and the DISCO-88 codes per se, although the DISCO-88 code-specific agreement varied across digit levels and time periods.