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This study investigated the challenges and facilitators of occupational epidemiology (OE) research in the UK, and evaluated the impact of these challenges. Semi-structured in-depth interviews with leading UK-based OE researchers, and a survey of UK-based OE researchers were conducted. Seven leading researchers were interviewed, and there were 54 survey respondents. Key reported challenges for OE were diminishing resources during recent decades, influenced by social, economic and political drivers, and changing fashions in research policy. Consequently, the community is getting smaller and less influential. These challenges may have negatively affected OE research, causing it to fail to keep pace with recent methodological development and impacting its output of high-quality research. Better communication with, and support from other researchers and relevant policy and funding stakeholders was identified as the main facilitators to OE research. Many diseases were initially discovered in workplaces, as these make exceptionally good study populations to accurately assess exposures. Due to the decline of manufacturing industry, there is a perception that occupational diseases are now a thing of the past. Nevertheless, new occupational exposures remain under-evaluated and the UK has become reliant on overseas epidemiology. This has been exacerbated by the decline in the academic occupational medicine base. Maintaining UK-based OE research is hence necessary for the future development of occupational health services and policies for the UK workforce.

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Context The greenspace sector includes a broad range of occupations: gardeners, landscapers, municipal workers, maintenance operators of public facilities, golf-course employees and other sports facilities, horticulturists, plant and tree nursery workers etc. The health impact of occupational pesticide exposure has mainly been studied among farmers. Other professionals such as greenspace workers are also extremely exposed, presenting specific exposure features (practices, types of pesticide used). The aim of this review was to summarize epidemiological literature that examine the relationship between pesticide exposure and the risk of cancer and long-term health effects in greenspace workers. Method Six main groups of greenspace workers were identified and examined through a systematic literature review based on PubMed and Scopus. The studies were then grouped according to their design, health outcomes and the type of population studied. Results Forty-four articles were selected among the 1679 identified. Fifteen studies were conducted exclusively among greenspace workers, while ten also studied these workers with other pesticide applicators. Six were cohorts from the general population in which greenspace workers were identified. Elevated risks were found in several studies for leukaemia, soft-tissue sarcoma, multiple myeloma, non-Hodgkin lymphoma and Parkinson's disease. Discussion The majority of studies used rough parameters for defining exposure such as job titles which could lead to the misclassification of exposure, with the risk of false or positive negative conclusions. Health outcomes were mainly collected through registries or death certificates, and information regarding potential confounders was often missing. Conclusion The review identified only 15 studies conducted exclusively among greenspace workers. Elevated risk was found for several sites of cancer and Parkinson's diseases. Further epidemiological research is needed, conducted specifically on these workers, to better characterize this population, its exposure to pesticides and the related health effects.

I aimed to assess current practices and opportunities for addressing the problem of errors in exposure in occupational epidemiology. Occupational epidemiologists appreciate that errors in exposure are a concern, but almost none correct for these errors, although there are currently no theoretical and practical barriers for this inertia. The most serious barrier to change is a faulty belief that a well-conducted epidemiologic study suffers only non-differential exposure misclassification and that its sole impact is to attenuate risk gradients, causing a false negative. On the contrary, differential exposure misclassification is the most defensible model in occupational epidemiology, and errors in exposure increase chance of both false positive and negative results. Resistance to mathematical adjustment (correction) for errors in exposure is equivalent to denying the value of more valid exposure estimates and undermines the discipline’s relevance to protection of workers by informing workplace exposure limits.

INTRODUCTION: The 2010 Deepwater Horizon (DWH) disaster exposed tens of thousands of oil spill response and cleanup (OSRC) workers to hydrocarbons and other hazardous chemicals. Some hydrocarbons, such as toluene and hexane, have been found to have acute adverse effects on the central nervous system in occupational settings. However, no studies have examined the association between oil spill exposures and neurobehavioral function. METHODS: We used data from the Gulf Long-term Follow-up Study, a cohort of adults who worked on the DWH response and cleanup. Total hydrocarbon (THC) exposure attributed to oil spill cleanup work was estimated from a job-exposure matrix linking air measurement data to detailed cleanup work histories. Participants were also categorized into 6 job categories, or OSRC classes, based on their activity with the highest exposure. Neurobehavioral performance was assessed at a clinical exam 4–6 years after the spill. We used multivariable linear regression to evaluate relationships of ordinal THC levels and OSRC classes with 16 neurobehavioral outcomes. RESULTS: We found limited evidence of associations between THC levels or OSRC classes and decreased neurobehavioral function, including attention, memory, and executive function. Workers exposed to ≥3 ppm THC scored significantly worse (difference(1.0–2.9ppm) =−0.39, 95% confidence interval (CI)=−0.74, −0.04) than workers exposed to

The healthy worker survivor bias is well-recognized in occupational epidemiology. Three component associations are necessary for this bias to occur: i) prior exposure and employment status; ii) employment status and subsequent exposure; and iii) employment status and mortality. Together, these associations result in time-varying confounding affected by prior exposure. We illustrate how these associations can be assessed using standard regression methods.We use data from 2975 asbestos textile factory workers hired between January 1940 and December 1965 and followed for lung cancer mortality through December 2001.At entry, median age was 24 years, with 42% female and 19% non-Caucasian. Over follow-up, 21% and 17% of person-years were classified as at work and exposed to any asbestos, respectively. For a 100 fiber-year/mL increase in cumulative asbestos, the covariate-adjusted hazard of leaving work decreased by 52% (95% confidence interval [CI], 46-58). The association between employment status and subsequent asbestos exposure was strong due to nonpositivity: 88.3% of person-years at work (95% CI, 87.0-89.5) were classified as exposed to any asbestos; no person-years were classified as exposed to asbestos after leaving work. Finally, leaving active employment was associated with a 48% (95% CI, 9-71) decrease in the covariate-adjusted hazard of lung cancer mortality.We found strong associations for the components of the healthy worker survivor bias in these data. Standard methods, which fail to properly account for time-varying confounding affected by prior exposure, may provide biased estimates of the effect of asbestos on lung cancer mortality under these conditions.

Purpose There are different mineral classes of asbestos, including serpentines and amphiboles. Chrysotile is the main type of serpentine and by far the most frequently used type of asbestos (about 95% of world production and use). There has been continuing controversy over the capability of chrysotile asbestos to cause pleural and peritoneal mesothelioma. This review is to help clarify the issue by detailing cases and epidemiology studies worldwide where chrysotile is the exclusive or overwhelming fiber exposure. Methods A worldwide literature review was conducted of asbestos and associated mesothelioma including case series, case-control and cohort epidemiology studies searching for well documented chrysotile asbestos associated mesothelioma cases. Results Chrysotile asbestos exposures have occurred in many countries around the world from mining, manufacturing and community exposures. There have been many documented cases of mesothelioma from those exposures. Conclusions Chrysotile asbestos, along with all other types of asbestos, has caused mesothelioma and a world-wide ban of all asbestos is warranted to stop an epidemic of mesothelioma.

The classification of jobs or workers by exposure is an important undertaking in any occupational epidemiological study. Hitherto, the exposure classification designs have been strongly motivated by a desire to generate a sufficient number of exposure classes for the determination of a potential exposure-response relationship. Thus, the partitioning of exposures has been more or less arbitrary. The misclassification problems created by the selection of an arbitrary number of exposure assignment classes have not been addressed. In any quantitative exposure classification scheme, specific job titles may be indistinguishable in existing employment records; therefore, between worker variability must be addressed when characterizing worker exposures. Also, industrial hygiene exposure measurements frequently used to characterize worker exposures are often treated as valid representations of exposures; but they are neither random nor systematic evaluations of worker exposures. As a result they do not represent sampling from the proper exposure stratification of workers. These observations suggest that the selection of exposure groups should be based on a more rigorous examination of the data and its limitations. Considering the probability of any given worker being placed into the proper class as the probability of finding the mean exposure for that worker within the class boundary, the general equations to quantify the misclassification rates for any classification design as well as the exposure class limits and their width for any acceptable misclassification rate are developed. If between worker variability could not be calculated from the available exposure measurements, then it might be estimated from the proper data compiled from the literature. By considering an acceptable level of exposure misclassification, it is possible to calculate the allowable number of exposure classes and the proper partitioning ratio for these classes. Thus, the trade-off between misclassification and number of exposure classes might be a satisfactory solution to this difficulty encountered in occupational epidemiology.

The DuPont Company has maintained a mortality registry for all active and pensioned U.S. employees since 1957. Standardized mortality ratios (SMRs) for each plant site in the U.S. can be calculated based on the comparison with the entire U.S. DuPont population or with a regional subset of DuPont employees. We compared the SMRs derived from a large, international cohort mortality study of chloroprene workers (IISRP study) with those derived from the entire DuPont Registry and appropriate subpopulations of the registry for two U.S. neoprene plants--Louisville (Kentucky) and Pontchartrain (Louisiana). SMRs from the IISRP study for the Louisville cohort based on national rates for all causes of death, all cancers, respiratory cancer, and liver cancer are higher than those based on local mortality rates. Both the national and local comparisons (several counties surrounding each plant) for all-cancer SMRs are lower than 1.0, the local comparison being statistically significantly reduced. In contrast, the SMRs based on the total U.S. DuPont worker mortality rates for all causes of death (1.13), all cancers (1.11), and respiratory cancers (1.37) are statistically significantly increased. The SMR for liver cancer (1.27), although elevated, is not statistically significant. SMRs based on DuPont Region 1 were closer to 1.0, and the SMR for all cancers was no longer significant. Stratification of the Louisville subcohort of males using the same cumulative exposure categories used in the IISRP study yielded SMRs calculated against DuPont Region 1 that were generally higher than those calculated against U.S. and local rates. Only the third exposure category showed SMRs statistically significantly above 1.0 for all cancers and for cancer of bronchus, trachea, and lung. However, there does not appear to be an exposure-response trend. The SMRs from the IISRP study for the Pontchartrain cohort based on national rates are higher than those based on local rates for all causes of death, but all are less than 1.0. The all-cause SMRs for both local and national comparisons are significantly reduced. There were no deaths from liver cancers observed in this cohort. Comparisons of the Pontchartrain cohort against the total U.S. DuPont worker mortality rates resulted in higher SMRs for all causes of death (0.98), all cancers (1.03), and respiratory cancer (1.08), but none were statistically significant. SMRs based on DuPont Region 2 showed very little change from those based on the total registry. The use of reference rates based on regional workers in the same large company produces SMRs lower than those based on the entire company population (regional socio-cultural effects) but higher than those based on geographically closer local general populations (healthy worker effect). The healthy worker effect is seen in cancer mortality rates as well as in other chronic diseases.

In a four-facility occupational epidemiology study of chloroprene monomer and polymer production workers, the chloroprene (CD) and vinyl chloride monomer (VCM) exposures were modeled for plant specific job title classes. In two facilities an acetylene-based process was used and in the other two plants only a butadiene-based process was used in the monomer synthesis. In the Acetylene process VCM was an undesirable by-product to be removed. In the newer butadiene-based process, VCM was not involved and the exposures to CD were considerably lower than they were in the earlier years. One of the limiting factors was the operator rotation within a number of job titles. This rotation and inability to differentiate between job titles subsumed in job classifications recorded in the work histories required an exposure classification scheme based on an order of magnitude separation of exposure classes. In the four facilities with considerable variation in the mix of the production methods, the CD exposures were remarkably similar in both calculated and measured values. The reductions in exposures were much more dependent upon the improvement of the production methods, rather than deliberate exposure control for occupational hygiene considerations. This is reasonable since the exposures were generally lower than the coeval exposure limits and/or guidelines. The estimated exposures were less than 100 ppm in the pre-1960 era and less than 10 ppm in the 1960-1980 era, less than 1 ppm 1980-1990 era and less than 0.5 ppm thereafter. The exposures were categorized in four classes for VCM and six classes for CD. The characteristic class exposure values were used to cumulate individual exposures over time with a quantification of the potential range for exposures that are reasonably certain to ascribe correct ranking to job classes.

Quantitative risk assessment provides formalized scientific input for setting occupational and environmental standards for potentially toxic exposures. We describe the methods to perform quantitative cancer risk assessment based on published epidemiological literature using a hand calculator or spreadsheet. These methods are illustrated for some suspected or known human carcinogens, including perchloroethylene, formaldehyde, benzene and nickel. The approach to cancer risk assessment presented here may prove useful for those without access to original data from epidemiologic studies. The methods described should facilitate the use of published epidemiological data in the estimation of cancer risk in the general or working population.

Background There is no unanimous agreement on the use of a diluent step to preface methacholine challenge testing. The "pros" for this step are that it allows a better training of the patient; the "cons" are that it requires additional time and effort. Objective We examined if there were any systematic effects when either the baseline or postdiluent (saline) forced expiratory volume in 1 second (FEV 1 ) was used to define the reactivity status. Methods All methacholine challenge tests performed during a 1-year period by a group of occupationally exposed workers (n = 183) were examined. Results The mean percentage change in FEV 1 from baseline to postsaline was −1.44 (± 3.47)% and the mean absolute change was −0.043 (± 0.11) L ( P 1 from baseline were −12.7% and +10.9%, respectively. Three subjects had a fall in FEV 1 after saline of 10% or more and were not given methacholine. From the remaining 180 subjects, 172 were equally classified as reactors (n = 67) or nonreactors (n = 105), both by baseline FEV 1 and postsaline FEV 1 . Eight subjects were classified as reactors by baseline FEV 1 but as nonreactors by saline FEV 1 . In these subjects, the average FEV 1 dropped 4.9% from baseline to saline and 17.3% from saline to end-test; thus, the total FEV 1 drop (22.5%) exceeded the 20% required for the test to be positive. Among reactors, no relationship was found between the response to saline and the subsequent response to methacholine ( r = 0.13). Conclusions Our data did not provide evidence to support the compulsory use of a diluent step when measuring bronchial responsiveness in populations. In general, the diluent step added time and expense to the test and, on occasion, forced a greater absolute drop in FEV 1 than is needed to demonstrate bronchial hyperresponsiveness.

Occupationally related hand dermatitis has been attributed to frequent hand-washing, exposure to possible sensitizers and latex glove use. The authors conducted a study to determine the prevalence of occupationally related hand dermatitis in dental personnel. They found that 75 (19.2 percent) of 390 subjects self-reported they had a positive history of hand dermatitis. Further testing of 53 of these subjects indicated that only 9.4 percent reacted to the 45 allergens tested, and 3.8 percent had an allergy to latex.

Workplace description is an operation indispensable for the identification of professional risks and, in fulfillment of that objective, can best be accomplished by listing the constituent tasks associated with each job. This article presents a software in Visual-Basic to be run on a portable micro-computer, which facilitates this process according to these aims. The occupational physician and safety engineer can make good use of the exposure database resulting from the application of this program. Job histories are built automatically, while workers with similar exposures are grouped together and job-exposure matrices are elaborated. This information, computerized, sorted and re-assembled, can then be used effectively for studies in the field of occupational epidemiology.

Reports of hypersensitivity to latex are growing among oral health care workers, who have a high degree of exposure to latex products. The authors undertook a study to determine the prevalence of latex hypersensitivity among oral health care workers in a hospital dental practice. Among the 34 people who participated in the study, 12 percent had positive results in a skin prick test for latex. This suggests that the true prevalence rate of immediate hypersensitivity to latex in this group of oral health care workers is similar to that in other health care workers who use latex gloves frequently.

Irritant contact dermatitis is the most frequent occupational skin disease resulting in considerable morbidity and economic losses to workers, employers, and insurers. This article reviews pathogenesis, epidemiology, diagnosis, and treatment of irritant dermatitis at the workplace and stresses the importance of integrated preventive measures that must be implemented by companies and employees to achieve optimal efficacy.

ResumenLos estudios de mortalidad proporcional son una herramienta de uso común en epidemiología laboral. En esta revisión se discuten los principales sesgos que afectan a estos diseños, sobre todo el efecto del trabajador sano. Dentro del análisis, se realiza un recuerdo de las diferentes opciones: el análisis de mortalidad proporcional, la razón de mortalidad estandarizada y la razón de ventaja, y las condiciones que han de reunir para que la inferencia sea válida. Dentro de los criterios de selección, el empleo de sujetos muertos en una investigación condiciona la presencia de varios inconvenientes. Tomando como base un recuerdo breve de los hechos más destacados en el análisis de un estudio de mortalidad proporcional, se establece un primer criterio para la selección de los grupos participantes: ausencia de relación entre la exposición y las enfermedades productoras de muerte del grupo de referencia, un hecho compartido con los estudios de casos y controles. A continuación, tomando como base la relación existente entre las tasas de mortalidad y las de incidencia, se ofrecen los criterios generales a seguir en la elección de las enfermedades candidatas a ser estudiadas por este tipo de diseños sin afectar la inferencia. Este tipo de diseños no introducen error cuando la enfermedad de los casos es rara e irreversible y el sesgo es negativo cuando el factor que se estudia acorta la duración del proceso. En otras circunstancias el sesgo es variable, aunque normalmente es también negativo.SummaryProportional mortality designs are used widespread in occupational epidemiology. In this review those biases which can affect them, mainly the healthy worker bias, are discussed. Several options for their analysis and the assumptions to be accomplished for validity are reviewed: proportionate mortality analysis, stardardized mortality ratio, and odds ratio. The Inclusion of dead participants in a research exhibits several drawbacks. Starting out from the analysis of this sort of designs, the first criterium to select diseases is similar to case-control studies: the reference group must not include diseases related with the exposure under study. Analyzing the relationship between mortallity and incidence rates, criteria to select diseases to be investigated by proportional mortality studies are offered. These designs yield a valid inference when the disease is rare and irreversible. If the exposure shortens duration of disease, atoward-the-null bias is introduced. The direction of bias is variable under other circumstances, although it shows a trend to be negative.