Retrospective Exposure Assessment Research Articles

Retrospective Assessment of Exposure to Air Pollution in the GAZEL French Cohort Study

Retrospective Assessment of Exposure to Air Pollution in the GAZEL French Cohort Study

The relation between type of farming and prevalence of Parkinson's disease among agricultural workers in five french districts

Retrospective assessment of pesticide exposure is complex; however, patterns of pesticide use strongly depend on farming type, which is easier to assess than pesticide exposure. Our aim was to estimate Parkinson's disease (PD) prevalence in five French districts in 2007 among affiliates of Mutualité Sociale Agricole (MSA) and to investigate the relation between PD prevalence and farming type. We identified PD cases from administrative files as persons who used levodopa and/or benefited from free health care for PD. Densities of 16 farming types were defined at the canton of residence level (1988 French agricultural census). We used logistic regression to study the relation between PD prevalence and density of farming types and a semi-Bayes approach to deal with correlated exposures. We identified 1,659 PD cases, yielding an age- and sex-standardized PD prevalence of 3.01/1,000. Prevalence increased with age and was higher in men than women. We found a higher PD prevalence among affiliates living in cantons characterized by a higher density of farms specialized in fruits and permanent crops (multivariable semi-Bayes model: OR(4+5 vs 1+2+3 quintiles) = 1.21, 95% CI = 1.08-1.36; test for trend, P = 0.035). In France, farms specialized in fruits and permanent crops rank first in terms of insecticide use per hectare. Our findings are consistent with studies reporting an association between PD and insecticide use and show that workers in farms specialized in fruits or permanent crops may be an occupational group at higher PD risk.

Exposure Assessment for a Nested Case–Control Study of Lung Cancer among European Asphalt Workers

Development of a method for retrospective assessment of exposure to bitumen fume, bitumen condensate, organic vapour, polycyclic aromatic hydrocarbons, and co-exposures to known or suspected lung carcinogens for a nested case-control study of lung cancer mortality among European asphalt workers. Company questionnaires and structured questionnaires used in interviews and industry-specific job-exposure matrices (JEMs) were elaborated and applied. Three sources of information were eventually used for exposure assessment and assignment: (i) data obtained in cohort phase, (ii) data from living subjects, next-of-kin, and fellow-workers questionnaires, and (iii) JEMs for bitumen exposure by inhalation and via skin and co-exposures to known or suspected lung carcinogens within and outside cohort companies. Inhalation and dermal exposure estimates for bitumen were adjusted for time trends, time spent in a job, and other determinants of exposure (e.g. oil gravel paving). Clothing patterns, personal protective devices, and personal hygiene were taken into consideration while estimating dermal exposure. Occupational exposures could be assessed for 433 cases and 1253 controls for relevant time periods. Only 43% of work histories were spent inside original asphalt and construction companies. A total of 95.8% of job periods in cohort companies could be coded at a more detailed level. Imputation of work time and 'hygienic behaviour' multipliers was needed for <10% of work history years. Overall, downward trends in exposure were present and differences existed between countries and companies. As expected, correlations were strongest (r > 0.7) among bitumen-related agents, while correlations between coal tar, bitumen-related agents, and established lung carcinogens were weaker (r < 0.4). A systematic and detailed approach was developed to estimate inhalation and dermal exposure for a nested case-control study among asphalt workers.

Prospective and Retrospective Exposure Assessment

Though prospective regulatory exposure assessment and retrospective forensic exposure reconstruction rely on the same tools, they have a very different focus, require a distinct approach, and depend on different types of data. Inappropriate application of prospective regulatory exposure assessment methods to forensic exposure reconstruction can result in exposure estimates that differ significantly from actual historical exposures. This article compares prospective exposure assessment and forensic exposure reconstruction, with the goal of describing their distinctive focuses (e.g., population-based versus individual-based) and data needs.

Quantification of ETS exposure in hospitality workers who have never smoked

BackgroundEnvironmental Tobacco Smoke (ETS) was classified as human carcinogen (K1) by the German Research Council in 1998. According to epidemiological studies, the relative risk especially for lung cancer might be twice as high in persons who have never smoked but who are in the highest exposure category, for example hospitality workers. In order to implement these results in the German regulations on occupational illnesses, a valid method is needed to retrospectively assess the cumulative ETS exposure in the hospitality environment.MethodsA literature-based review was carried out to locate a method that can be used for the German hospitality sector. Studies assessing ETS exposure using biological markers (for example urinary cotinine, DNA adducts) or questionnaires were excluded. Biological markers are not considered relevant as they assess exposure only over the last hours, weeks or months. Self-reported exposure based on questionnaires also does not seem adequate for medico-legal purposes. Therefore, retrospective exposure assessment should be based on mathematical models to approximate past exposure.ResultsFor this purpose a validated model developed by Repace and Lowrey was considered appropriate. It offers the possibility of retrospectively assessing exposure with existing parameters (such as environmental dimensions, average number of smokers, ventilation characteristics and duration of exposure). The relative risk of lung cancer can then be estimated based on the individual cumulative exposure of the worker.ConclusionIn conclusion, having adapted it to the German hospitality sector, an existing mathematical model appears to be capable of approximating the cumulative exposure. However, the level of uncertainty of these approximations has to be taken into account, especially for diseases with a long latency period such as lung cancer.

Sequential hair mercury in mothers and children from a traditional riverine population of the Rio Tapajós, Amazonia: Seasonal changes

Riverine populations of the Brazilian Amazon depend on fish for their principal source of protein, which changes in availability with seasonal fluctuations in the aquatic ecosystem. We report seasonal (high and low waters) and interannual changes in total mercury and methylmercury concentrations in hair of subsistence fish-eaters from a traditional riverine village on the banks of the Rio Tapajós in the Brazilian Amazonia. Retrospective exposure assessment was conducted from hair concentrations in segments representative of 2 years. A total of 32 mothers and their 51 children were studied. They reported high fish consumption (4–14 times a week). Ranges of total mercury and methylmercury concentrations in hair were 1.0–51.0 and 0.5–41.4 μg g −1, with means of 12.4 and 10.2 μg g −1, respectively. The relative mean value for methylmercury was 80%. There was a significant correlation between mothers and children for both total-Hg ( r=0.4826; P=0.003) and methyl-Hg ( r=0.5214; P=0.004). Mercury concentrations along hair strands of individuals showed significant variation coinciding with seasonal high and low waters. The changes in the aquatic environment impacted fish species availability, which is reflected in the total and MeHg concentrations in hair.

Development of a Task-Exposure Matrix (TEM) for Pesticide Use (TEMPEST)

Pesticides have been associated with increased risks for a range of conditions including Parkinson's disease, but identifying the agents responsible has proven challenging. Improved pesticide exposure estimates would increase the power of epidemiological studies to detect such an association if one exists. Categories of pesticide use were identified from the tasks reported in a previous community-based case-control study in Scotland. Typical pesticides used in each task in each decade were identified from published scientific and grey literature and from expert interviews, with the number of potential agents collapsed into 10 groups of pesticides. A pesticide usage database was then created, using the task list and the typical pesticide groups employed in those tasks across seven decades spanning the period 1945-2005. Information about the method of application and concentration of pesticides used in these tasks was then incorporated into the database. A list was generated of 81 tasks involving pesticide exposure in Scotland covering seven decades producing a total of 846 task per pesticide per decade combinations. A Task-Exposure Matrix for PESTicides (TEMPEST) was produced by two occupational hygienists who quantified the likely probability and intensity of inhalation and dermal exposures for each pesticide group for a given use during each decade. TEMPEST provides a basis for assessing exposures to specific pesticide groups in Scotland covering the period 1945-2005. The methods used to develop TEMPEST could be used in a retrospective assessment of occupational exposure to pesticides for Scottish epidemiological studies or adapted for use in other countries.

An Investigation of the Adjustment of Retrospective Noise Exposure for Use of Hearing Protection Devices

To account for use of hearing protection devices (HPDs) in retrospective noise exposure assessment, adjust noise exposure estimates accordingly, and validate the adjusted estimates. A previous study in the same working population showed a stronger relation for noise and acute myocardial infarction among those who did not wear HPD. Because accurate noise exposure assessment is complicated by the use of HPD, we previously developed a multilevel model of the likelihood of HPD use for British Columbia (Canada) lumber mill workers. Historical estimates of noise exposure can be adjusted according to models predictions and a reduction in misclassifying workers, exposure is expected. Work history and exposure information were obtained for 13,147 lumber mill workers followed from 1909 until 1998. Audiometric data for the cohort, including hearing threshold levels at several pure tone frequencies, were obtained from the local regulatory agency for the period from 1978 to 2003. Following the modeling of HPD use, noise estimates were adjusted according to models predictions and attenuation factors based on existing research and standards. Adjusted and unadjusted noise metrics were compared by investigating their ability to predict noise-induced hearing loss. We showed a 4-fold increase in the noise exposure and hearing loss slope, after adjusting for HPD use, while controlling for gender, age, race, as well as medical and non-occupational confounding variables. While the relative difference before and after adjustment for use of HPD is considerable, we observed a subtle absolute magnitude of the effect. Using noise-induced hearing loss as a 'gold standard' for testing the assessment of retrospective noise exposure estimates should continue to be investigated.

Retrospective exposure assessment to airborne asbestos among power industry workers

BackgroundA method of individually assessing former exposure to asbestos fibres is a precondition of risk-differentiated health surveillance. The main aims of our study were to assess former levels of airborne asbestos exposure in the power industry in Germany and to propose a basic strategy for health surveillance and the early detection of asbestos related diseases.MethodsBetween March 2002 and the end of 2006, we conducted a retrospective questionnaire based survey of occupational tasks and exposures with airborne asbestos fibres in a cohort of 8632 formerly asbestos exposed power industry workers. The data on exposure and occupation were entered into a specially designed computer programme, based on ambient monitoring of airborne asbestos fibre concentrations. The cumulative asbestos exposure was expressed as the product of the eight-hour time weighted average and the total duration of exposure in fibre years (fibres/cubic centimetre-years).ResultsData of 7775 (90% of the total) participants working in installations for power generation, power distribution or gas supply could be evaluated. The power generation group (n = 5284) had a mean age of 56 years, were exposed for 20 years and had an average cumulative asbestos exposure of 42 fibre years. The occupational group of "metalworkers" (n = 1600) had the highest mean value of 79 fibre years. The corresponding results for the power distribution group (n = 2491) were a mean age of 45 years, a mean exposure duration of 12 years and an average cumulative asbestos exposure of only 2.5 fibre years. The gas supply workers (n = 512) had a mean age of 54 years and a mean duration of exposure of 15 years.ConclusionsWhile the surveyed cohort as a whole was heavily exposed to asbestos dust, the power distribution group had a mean cumulative exposure of only 6% of that found in the power generation group. Based on the presented data, risk-differentiated disease surveillance focusing on metalworkers and electricians from the power generating industry seems justified. That combined with a sensitive examination technique would allow detecting asbestos related diseases early and efficiently.

Impact of Pre- and Postnatal Exposure to Environmental Tobacco Smoke (Ets) on Sudden Infant Death Syndrome (Sids)

ISEE-0399 Background and Objective: The aim of this review is to critically evaluate the impact of prenatal and postnatal exposure to environmental tobacco smoke (ETS) on the sudden infant death syndrome (SIDS) separately. The main challenge of this analysis is a possible correlation between maternal smoking during pregnancy and postnatal ETS exposure. Methods: We identified eligible studies by means of a systematic literature search. For prenatal exposure we included studies with information about maternal smoking during pregnancy. For postnatal exposure we restricted our evaluation to studies that quantified the risk for postnatal exposure either by adjusting their analysis for maternal smoking during pregnancy or by conducting stratified analysis in non-smoking mothers. Pooled relative risks were obtained by meta-analysis. Results: From 736 potentially eligible studies, 13 studies on maternal smoking during pregnancy were identified and seven case-control studies on postnatal exposure. The pooled relative risk associated with paternal smoking after birth was RR = 1.62 (95% Confidence Interval: 1.34-1.94). For maternal smoking after pregnancy, the pooled relative risk for SIDS adjusted for smoking during pregnancy was 2.28 (95% CI: 1.41-3.69). The relative risk of maternal smoking during pregnancy on SIDS was 2.49 (95% CI: 1.84-3.38) based on 5 studies with prospective exposure assessment and 2.72 (95% CI: 2.28-3.23) based on eight studies with retrospective exposure assessment. Only two studies on prenatal exposure adjusted their analysis for postnatal ETS exposure: their pooled RR was 3.21 (2.42, 4.26). Conclusion: We found evidence that postnatal ETS exposure is a risk factor for SIDS independent of maternal smoking behaviour during pregnancy. Nevertheless, maternal smoking during pregnancy seems to be a somewhat higher risk factor. Interestingly, separate analyses of prospective and retrospective studies do not indicate the presence of recall bias in these studies.

Airborne Asbestos Concentrations Associated with Heavy Equipment Brake Removal

Asbestos-containing brake linings were used in heavy-duty construction equipment such as tractors, backhoes, and bulldozers prior to the 1980s. While several published studies have evaluated exposures to mechanics during brake repair work, most have focused on automobiles and light trucks, not on heavy agricultural or construction vehicles. The purpose of this study is to characterize the airborne concentration of asbestos to workers and bystanders from brake wear debris during brake removal from 12 loader/backhoes and tractors manufactured between 1960 and 1980. Asbestos content in brake lining (average 20% chrysotile by polarized light microscopy) and brake wear debris [average 0.49% chrysotile by transmission electron microscopy (TEM)] was also quantified. Breathing zone samples on the lapel of mechanics (n = 44) and area samples at bystander (n = 34), remote (n = 22), and ambient (n = 12) locations were collected during 12 brake changes and analyzed using phase contrast microscopy (PCM) [National Institute for Occupational Safety and Health (NIOSH) 7400] and TEM (NIOSH 7402). In addition, the fiber distribution by size and morphology was evaluated according to the International Organization for Standardization method for asbestos. Applying the ratio of asbestos fibers:total fibers (including non-asbestos) as determined by TEM to the PCM results, the average airborne chrysotile concentrations (PCM equivalent) were 0.024 f/cc for the mechanic and 0.009 f/cc for persons standing 1.2-3.1 m from the activity during the period of exposure ( approximately 0.5 to 1 h). Considering the time involved in the activity, and assuming three brake jobs per shift, these results would convert to an average 8-h time-weighted average of 0.009 f/cc for a mechanic and 0.006 f/cc for a bystander. The results indicate that (i) the airborne concentrations for worker and bystander samples were significantly less than the current occupational exposure limit of 0.1 f/cc; (ii) approximately 2% of respirable fibers were >20 microm in length; and (iii) approximately 95% of chrysotile in the brake linings degraded in the friction process. The industrial hygiene data presented here should be useful for conducting retrospective and current exposure assessments of individuals, as well as hazard assessments of work activities that involve repairing and replacing asbestos-containing brakes in heavy construction equipment.

Retrospective exposure assessment in environmental epidemiology

Lack of exposure data is the most commonly cited factor preventing identification of causal association between environmental and occupational risk factors and health effects.1 Environmental exposure assessment presents more challenges...

Risk Factors for Occupational Osteoarthritis

Sixteen articles published between 1987 and 2008 regarding work-related activities as risk factors for osteoarthritis of the knee, hand, foot, hip, and cervical spine were chronologically reviewed. Despite challenges (e.g., nonresponse bias, inadequate sample size, and retrospective exposure assessment), the review findings indicated a strong relationship between physical strain experienced while performing physically demanding jobs and the incidence of osteoarthritis. This conclusion informs occupational health nurses' work and design of work policies.

Risk Factors for Occupational Osteoarthritis

Sixteen articles published between 1987 and 2008 regarding work-related activities as risk factors for osteoarthritis of the knee, hand, foot, hip, and cervical spine were chronologically reviewed. Despite challenges (e.g., nonresponse bias, inadequate sample size, and retrospective exposure assessment), the review findings indicated a strong relationship between physical strain experienced while performing physically demanding jobs and the incidence of osteoarthritis. This conclusion informs occupational health nurses’ work and design of work policies.

Feasibility of a cohort study on health risks caused by occupational exposure to radiofrequency electromagnetic fields

BackgroundThe aim of this study was to examine the feasibility of performing a cohort study on health risks from occupational exposure to radiofrequency electromagnetic fields (RF-EMF) in Germany.MethodsA set of criteria was developed to evaluate the feasibility of such a cohort study. The criteria aimed at conditions of exposure and exposure assessment (level, duration, preferably on an individual basis), the possibility to assemble a cohort and the feasibility of ascertaining various disease endpoints.ResultsTwenty occupational settings with workers potentially exposed to RF-EMF and, in addition, a cohort of amateur radio operators were considered. Based on expert ratings, literature reviews and our set of predefined criteria, three of the cohorts were identified as promising for further evaluation: the personnel (technicians) of medium/short wave broadcasting stations, amateur radio operators, and workers on dielectric heat sealers. After further analyses, the cohort of workers on dielectric heat sealers seems not to be feasible due to the small number of exposed workers available and to the difficulty of assessing exposure (exposure depends heavily on the respective working process and mixture of exposures, e.g. plastic vapours), although exposure was highest in this occupational setting. The advantage of the cohort of amateur radio operators was the large number of persons it includes, while the advantage of the cohort of personnel working at broadcasting stations was the quality of retrospective exposure assessment. However, in the cohort of amateur radio operators the exposure assessment was limited, and the cohort of technicians was hampered by the small number of persons working in this profession.ConclusionThe majority of occupational groups exposed to RF-EMF are not practicable for setting up an occupational cohort study due to the small numbers of exposed subjects or due to exposure levels being only marginally higher than those of the general public.

Dose Reconstruction: The Use of Dose Reconstruction in the Determination of Human Exposure

Abstract Dose reconstruction is a scientifically acceptable means to perform a retrograde or retrospective analysis of the preceding dose or for numerous exposures of an individual. It is used in a wide range of scientific applications, especially when contemporaneous or near contemporaneous exposure measurements from the time of interest or consideration are undefined. Dose reconstruction is used to attempt to consider numerous individual exposures. It accommodates for fluctuations in the intensity of the exposures and totaling the exposures into an estimated dose over a definitive time period or duration. This paper reviews a method to perform dose reconstruction when limited information is provided concerning the relevant exposure parameters. This methodology is not intended to replace the use of other dose reconstruction models that are available when definitive exposure parameter values are available. We show through the scientific literature and several examples using maximal or near maximal parameter values in calculating the dose that “dose reconstruction” is a valid method to determine retrospective exposure assessments. These retrospective exposure assessments may be used for the purposes of determining the maximal risk or a safety assessment, risk comparison, or toxicological relatedness or risk. The application of such a methodology is at times challenging in the authors’ work due to the limitations in the facts that are provided to them which describe the exposure parameters of an individual. These methods to perform the dose reconstructions are based on sound scientific foundation and are extremely versatile models which can be used in a variety of situations.

Retrospective Exposure Assessment for Carcinogenic Agents in Bitumen Waterproofing Industry in Finland and Denmark

The purpose of the study was (i) to identify the carcinogenic agents that may cause confounding when studying the exposure-response relationship between bitumen fume exposure and cancer among roofing membrane-manufacturing workers and roofers and (ii) to assess exposures to the identified carcinogens and bitumen fume in roofing membrane manufacturing and roofing in Finland and Denmark from 1950 to 2005. Information on the use of carcinogenic agents and other relevant data were collected through semi-structured interviews of senior employees in the industry. Semi-quantitative exposure assessments were made on the basis of available measurement data and information obtained from the interviews and literature. Most of the production line workers in roofing membrane plants in Finland were exposed to asbestos until the mid-1970s. Also, some of the mixer operators in the plants were exposed to asbestos in Finland during the 1970s and in Denmark from the mid-1960s to the mid-1980s. In both countries, coal tar pitch was used in roofing membrane manufacturing until the mid-1960s, and consequently, exposure to polycyclic aromatic hydrocarbons (PAHs) in the plants was high in the 1950s and still significant in the early 1960s. Exposure of production line workers to quartz dust was high until the 1980s and is still relatively high compared with current occupational exposure limit values. Bitumen roofers' exposure to coal tar-derived PAHs may have been significant in both countries until the end of 1960s. Roofers' exposure to asbestos and quartz was estimated to have been near background level. The estimated average annual exposures to asbestos, coal tar-derived PAHs and quartz dust in the bitumen waterproofing industry in Finland and Denmark were significant in the past but have a clear declining trend. Exposure to bitumen fume was found to follow a similar trend.

A plea for rigorous and honest science: false positive findings and biased presentations in epidemiological studies

It is well recognized that weak exposure estimates may hamper the identiWcation of eVects in epidemiological investigations (Checkoway et al. 2004; Rothman et al. 2008). However, toxicologists and regulators should be aware of recent discussions about false positive Wndings generated by epidemiological studies and that these biased results were reported rather uncritically in peer-reviewed journals. BoVetta and co-workers showed in their commentary that publication bias was at work in studies on dioxin exposure and non-Hodgkin lymphoma, they identiWed overstated relative risk estimates in a couple of epidemiological studies on DDE and breast cancer, acrylonitrile and lung cancer, coVee and pancreatic cancer, induced abortion and breast cancer and herpes simplex/chlamydia exposure and cervical cancer (BoVetta et al. 2008). The often reported epidemiological association of passive smoking and breast cancer was proved to be an artefact probably caused by a reporting bias in studies with retrospective exposure assessment (Pirie et al. 2008). In addition, empirical evidence has accumulated that most newly discovered true associations are inXated (Ioannidis 2008a). Such distortions were shown for studies in occupational epidemiology and for some highly cited epidemiological papers. Both reviews (BoVetta et al. 2008; Ioannidis 2008a) demonstrated convincingly that wrong risk estimates were communicated by papers published in peer-reviewed journals due to uncontrolled upward biases in epidemiological studies. Furthermore, epidemiological risk estimates suVer from a bias away from the null even if the studies are unbiased in the usual sense (Senn 2008). This indirect bias is due to the “regression scissor” phenomenon: the regression line of y on x diVers from the line of x on y if the correlation is not perfect. Given the study is unbiased in the usual sense the expectation of the model-predicted response is identical with the true response. However, because the predicted response almost always suVers from limited precision the converse is almost never true. It follows that the association measured in a study is in fact inXated. This indirect bias is unavoidable in the usual situation of imprecise exposure estimates, imprecise covariate data and imprecise response information and it will operate in the epidemiological studies even if theses errors are not systematic. However, over and above these scientiWc problems generated by direct and indirect biases a discussion has started about distorted analyses and presentations of epidemiological studies in peer-reviewed journals (Ioannidis 2008b). In the following I’d like to discuss a recent example from environmental epidemiology (Slama et al. 2007). This study was published in environmental health perspectives (EHP), a journal that presents itself as a leader in the Weld “by publishing in a balanced and objective manner the best peer-reviewed research and most current and credible news of the Weld” (http://www.ehponline.org/docs/admin/mission. html). Unfortunately, EHP hesitated to accept a Letter to the Editor because the Journal rules do not allow publishing letters that are submitted more than 6 months after publication of the paper. Thus, I am grateful to the Editor of Archives of Toxicology for oVering me the opportunity to discuss the example in this Editorial. P. Morfeld Institute for Occupational Medicine of Cologne University, Cologne, Germany

A retrospective assessment of occupational noise exposures for a longitudinal epidemiological study

Objectives:Chronic exposure to high levels of noise may be associated with increased risk of cardiovascular disease. We therefore undertook a quantitative retrospective exposure assessment using predictive statistical modelling to estimate...

Using urban man-made ponds to reconstruct a 150-year history of air pollution in northwest England

A regional pollution history has been reconstructed for the borough of Halton (northwest England) from four urban ponds in north Cheshire and south Merseyside, using environmental analyses of lake sediment stratigraphies. Mineral magnetism, geochemistry and radiometric dating have produced profiles of pollution characteristics dating from the mid-nineteenth century to present day. These pollution profiles reflect the atmospheric deposition of a range of pollutants over 150 years of intensified industry. Distinct phases of pollution deposition and characteristics are identified reflecting: (1) intensification of industry in the nineteenth century; (2) expansion of industry during the twentieth century; (3) post 1956 Clean Air Acts. This work promotes the potential use of these pollution archives for use in epidemiology to better understand links between human health and environmental pollution, especially for diseases with long latency times, where retrospective pollution exposure assessments are important.