Microbial environment and autoimmune diseases: a long-term follow-up study of pigeon breeders

Background About 300.000 Danes suffer from type-I diabetes, rheumatoid arthritis, inflammatory bowel disease or other autoimmune diseases. Autoimmune diseases are on the rise in the industrialized world compared with less developed economies. Low diversity of the microbial environment has been hypothesized as a causal link in line with the microbial diversity hypothesis, the current version of the hygiene hypothesis.
Pigeon breeders have daily, close contact with pigeons and a rich microbial environment. This makes them ideal for investigating the hypothesized protective effect of a diverse microbial environment on autoimmune diseases.
Materials and methods We have established a cohort of 7000 pigeon breeders and 350.000 age- and sex-matched referents followed from 1980 until present time. We have detailed data on pigeon exposure, hospitalization and mediation use and potential confounders for the entire population and have earlier successfully analyzed the risk of interstitial lung diseases in this population (Cramer et al, 2016).
Contact Christine Cramer, MD, PhD-student, chcrch@rm.dk, Department of Public Health Aarhus University and Department of Occupational Medicine, Aarhus University Hospital.

Occupational exposures and shoulder disorders: a follow up study of surgery patients

Background The prognosis for shoulder disorders is an important public health concern, as it has considerable impact on sickness absence, utilisation of primary and secondary health services, and premature withdrawal from the labour market. Short-term prognosis for shoulder disorders has been well studied but with relatively heterogeneous results. The long-term prognosis is however less studied, and only few studies have included prognostic factors related to work. The aim of this study is to investigate the effect of occupational shoulder exposures on the long-term prognosis for shoulder surgery in terms of shoulder pain and physical functioning.
Materials and methods In 2010, we conducted a case-control study (N=5900) nested in a register-based cohort study of the entire Danish working population. Information on shoulder surgery was obtained using the Danish National Patient registers. Cases and controls received a questionnaire on job history, lifestyle factors, shoulder pain and physical functioning. Job histories were combined with a Shoulder job exposure matrix (JEM), which provide exposure intensities on measurement scales. A total of 1900 workers with shoulder surgery answered the questionnaire, and will comprise the population for this cohort study. The association between occupational shoulder exposures and shoulder pain and physical functioning will be analysed using logistic regression adjusted for potential confounders.
Discussion Knowledge of the effect of occupational shoulder exposures as a prognostic factor could influence the counselling given to workers with previous shoulder disorders.
Contact Annett Dalbøge, PhD, annett.dalboege@rm.dk, Department of Occupational Medicine, Aarhus University Hospital.

Organic dust, endotoxin exposure and asthma: a follow up study of farmers

Background and aims. Occupational asthma (OA) is one of the leading occupational respiratory diseases. Two major OA phenotypes have been described: allergic and non-allergic. The risk of asthma has long been perceived as being high among farmers, but recent cross-sectional studies suggest this to be true only for the non-allergic phenotype. For allergic asthma, indications towards a protective effect of adult farming exposures are growing.
Materials and methods We have followed 2000 young farmers and 400 controls in 1992 and again in 2007. Through questionnaires and health examinations we have collected extensive information on their medical history and health status including asthma, allergies, and other respiratory diseases. Lung function measurements and skin-prick tests were performed and detailed occupational histories as well as quantitative measurements of the farmers’ exposure to organic dusts and endotoxins have been collected.
The study provides a unique opportunity to investigate the incidence and remission of both phenotypes of OA in association with farming exposures. The results will impact the direction of preventive measures against OA and potentially lead to a breakthrough in the understanding of the casual relationship between adult microbial exposures and OA.
Contact Vivi Schlünssen, MD, PhD, Professor, vs@ph.au.dk, 28992499 & Grethe Elholm, Adjunkt, gelh@ph.au.dk, Department of Public Health, Aarhus University.

Identification of musculoskeletal health care encounters: an algorithm for general practice

Background Danish national health and social registers are widely use in epidemiological health care and occupational research. Danish national health registers contain a wide range of information on primary and secondary health care contacts, and hence fulfill important health care quality and society administration purposes. There are however, several limitations to the utility of register based data in epidemiological research. One such limitation is that health registers in primary care do not include clinical diagnoses, which means that it is not possible to separate contacts related to musculoskeletal disorders from other health problems in general practice. This limitation challenges to the quality and potential of register based research at the primary care level. A possible solution to this limitation could be to identify face-to-face encounters for musculoskeletal disorders in general practices based on a combination of data from different health registers but such an approach has not been tested and validated.
Aim The overall aim of this project is to validate a simple algorithm to identify musculoskeletal health care contacts in general practice based on several Danish national health registry sources.
The aim will be to test if the algorithm is able to: 1) correctly identify patients with face-to-face musculoskeletal contacts at the General Practitioner (GP), 2) correctly identify number of musculoskeletal face-to-face contacts at the GP.
In this project, the research-year student will work and collaborate with a number of GP’s as well as researchers at The Department of Occupational Medicine – University Clinic, Herning. Furthermore, the research-year student will get thorough knowledge of Danish national health registers and register based research.
Contact David H. Christiansen, Associate Professor, PhD, David.Christiansen@vest.rm.dk & Søren Mose. PhD student. MHSc. soemos@rm.dk, Department of Public Health, Aarhus University.

Occupational wood dust exposure and risk of sinonasal cancer: a follow-up study of the exposure response relation

Background and aim The discovery of the association between occupational wood dust exposure and adenocarcinoma of the sinonasal cavities was a landmark in cancer epidemiology (1). Since the first reports in the 1960s, several studies have confirmed the association. However, there is lack of knowledge about the exposure response relation based on quantitative exposure data that can guide evidence based regulatory exposure limits. Due to the rarity of sinonasal cancer, this will require exposure characterization of a large population that perhaps only is possible in Denmark because of national employment and health registers combined with extensive exposure data. The objective of this study is to characterize the exposure response relation between quantitative measures of wood dust exposure and the risk sinonasal cancer.
Materials and methods This is planned as a follow-up study of the entire Danish working population of 6 million since 1970. A total of 330.000 of these have been significantly wood dust exposed. For each year we will provide estimates of wood dust exposure levels by means of a quantitative job exposure matrix (JEM) based on 25,000 wood dust measurements 1970-2007.
All expected 1000 cases of sinonasal cancer will be identified in the national cancer register. Based on histology cases will be sub-classified as adenocarcinomas, squamous cell carcinomas, and others. Potential confounding from smoking and other factors will be adjusted for by a lifestyle-JEM. We will follow the study population from 1970 or from year of first wood dust exposure until a diagnosis of sinonasal cancer or censuring. Rate ratios (RR) will be estimated with Poisson regression and exposure-response relations between cumulative wood dust exposure and other exposure metrics will be investigated.
Contact: Vivi Schlünssen, vs@ph.au.dk, and Henrik Kolstad, professor, henkol@rm.dk, Department of Occupational Medicine, Aarhus University Hospital.
1. Acheson ED, Cowdell RH, Hadfield E, Macbeth RG. Nasal cancer in woodworkers in the furniture industry. Br Med J 1968 Jun 8;2(5605):587-596.

Ototoxic effects of styrene exposure: a long term study of reinforced plastics workers

Background and aims Styrene is an industrial monomer used worldwide in the manufacturing of synthetic rubbers, plastics and reinforced plastics. Styrene is a well-known neurotoxin with strong evidence of associations with reaction time and color vision among workers with long-term exposure. High-quality toxicological and mechanistic animal studies have shown a clear exposure response relation with increasing hearing threshold levels (1). Epidemiological studies are in line with the experimental evidence, however, we lack knowledge about the exposure response relation for different exposure metrics (cumulative exposure, peak exposure, resent exposure) and impact of noise exposure and other ototoxic exposures. The aim of this study is to characterize the exposure response relation between styrene exposure and hearing threshold levels in a large cohort of styrene exposed reinforced plastics workers.
Material and methods The study population is a subset of 72 000 workers of the Danish reinforced plastics industry followed 1968-2019. Styrene exposure is characterized full work histories and a quantitative industry specific job exposure matrix based on 3000 styrene measurements and job and task information. Noise is characterized with a population based quantitative JEM specifically developed for the Danish labor market. Audiometry recordings are obtained from a database encompassing all 200 000 audiometries conducted in Southern Denmark Region 1998-2019. Data will be analyzed with multiple linear regression adjusting for ototoxic pharmaceuticals, age, sex, calendar year, smoking and socioeconomic status. The study will also be able to assess interaction with noise exposure. The study will gain insight into the causal mechanisms of hearing loss, that affects most people by increasing age.
Contact: Zara Stokholm, MD, PhD, zarastok@rm.dk, and Henrik Kolstad, professor, henkol@rm.dk, Department of Occupational Medicine, Aarhus University Hospital.
1. Banton MI, Bus JS, Collins JJ, Delzell E, Gelbke HP, Kester JE, et al. Evaluation of potential health effects associated with occupational and environmental exposure to styrene - an update. J Toxicol Environ Health B Crit Rev. 2019;22(1-4):1-130.