Respiratory Impairment in Norwegian Salmon Industry Workers: A Cross-Sectional Study

Effects of Interventions to Prevent Work-Related Asthma, Allergy, and Other Hypersensitivity Reactions in Norwegian Salmon Industry Workers (SHInE): Protocol for a Pragmatic Allocated Intervention Trial and Related Substudies

BACKGROUND

Workers in the salmon processing industry have an increased risk of developing respiratory diseases and other hypersensitivity responses due to occupational exposure to bioaerosols containing fish proteins and microorganisms, and related allergens. Little is known about effective measures to reduce bioaerosol exposure and about the extent of skin complaints among workers. In addition, while identification of risk factors is a core activity in disease prevention strategies, there is increasing interest in health-promoting factors, which is an understudied area in the salmon processing industry.

OBJECTIVE

The overall aim of this ongoing study is to generate knowledge that can be used in tailored prevention of development or chronification of respiratory diseases, skin reactions, protein contact dermatitis, and allergy among salmon processing workers. The main objective is to identify effective methods to reduce bioaerosol exposure. Further objectives are to identify and characterize clinically relevant exposure agents, identify determinants of exposure, measure prevalence of work-related symptoms and disease, and identify health-promoting factors of the psychosocial work environment.

METHODS

Data are collected during field studies in 9 salmon processing plants along the Norwegian coastline. Data collection comprises exposure measurements, health examinations, and questionnaires. A wide range of laboratory analyses will be used for further analysis and characterization of exposure agents. Suitable statistical analysis will be applied to the various outcomes of this comprehensive study.

RESULTS

Data collection started in September 2021 and was anticipated to be completed by March 2023, but was delayed due to the COVID-19 pandemic. Baseline data from all 9 plants included 673 participants for the health examinations and a total of 869 personal exposure measurements. A total of 740 workers answered the study's main questionnaire on demographics, job characteristics, lifestyle, health, and health-promoting factors. Follow-up data collection is not completed yet.

CONCLUSIONS

This study will contribute to filling knowledge gaps concerning salmon workers' work environment. This includes effective workplace measures for bioaerosol exposure reduction, increased knowledge on hypersensitivity, allergy, respiratory and dermal health, as well as health-promoting workplace factors. Together this will give a basis for improving the work environment, preventing occupational health-related diseases, and developing occupational exposure limits, which in turn will benefit employees, employers, occupational health services, researchers, clinicians, decision makers, and other stakeholders.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05039229; https://www.clinicaltrials.gov/study/NCT05039229.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/48790.

Occupational Allergic Sensitization Among Workers Processing King Crab (Paralithodes camtschaticus) and Edible Crab (Cancer pagurus) in Norway and Identification of Novel Putative Allergenic Proteins

Introduction: Asthma and allergy occur frequently among seafood processing workers, with the highest prevalence seen in the crustacean processing industry. In this study we established for the first time the prevalence of allergic sensitization in the Norwegian king- and edible crab processing industry and characterized the IgE-reactive proteins.

Materials and Methods: Two populations of crab processing workers participated; 119 king crab and 65 edible crab workers. The investigation included information on work tasks and health through a detailed questionnaire. Allergic sensitization was investigated by crab-specific IgE quantification and skin prick tests (SPT) to four in-house prepared crab extracts; raw meat, cooked meat, raw intestines and raw shell. Allergen-specific IgE binding patterns were analyzed by IgE immunoblotting to the four allergen extracts using worker serum samples. Total proteins in crab SPT extracts and immunoblot-based IgE binding proteins were identified by mass spectrometric analysis.

Results: Positive SPTs were established in 17.5% of king- and 18.1% of edible crab workers, while elevated IgE to crab were demonstrated in 8.9% of king- and 12.2% of edible crab processing workers. There was no significant difference between the king and edible crab workers with respect to self-reported respiratory symptoms, elevated specific IgE to crab or SPT results. Individual workers exhibited differential IgE binding patterns to different crab extracts, with most frequent binding to tropomyosin and arginine kinase and two novel IgE binding proteins, hemocyanin and enolase, identified as king- and edible crab allergens.

Conclusions: Occupational exposure to king- and edible crabs may frequently cause IgE mediated allergic sensitization. Future investigations addressing the diagnostic value of crab allergens including tropomyosin and arginine kinase and the less well-known IgE-binding proteins hemocyanin and enolase in a component-resolved diagnostic approach to crab allergy should be encouraged.

Work-related Symptoms and Asthma among Fish Processing Workers

After observing several clinical patients with respiratory symptoms, we initiated a questionnaire survey to assess prevalence of and predictors for asthma and work-related symptoms among workers in fish processing plants. A questionnaire with items on work conditions, work-related symptoms, and respiratory symptoms/diseases was sent to 916 fish processing workers, the 1836 licenced fishermen in Sweden, and 1965 controls; of those, 43%, 57%, and 53%, respectively, responded. Risks, hazard ratios (HRs), and prevalence ratios (PRs) were calculated with Cox regression, and 95% confidence intervals (CIs) were computed. The risk of asthma among fish filleting workers was increased during the years working in the fish processing industry when compared to the other fish processing workers and controls (HR 3.6, 95% CI 1.6-8.1, adjusted for atopy, gender, and ever smoking). The filleters had an increased PR for most of the work-related respiratory symptoms investigated. All fish processing workers had a higher PR for flu-like symptoms. Use of a pressure sprayer was identified as a risk for asthma and respiratory symptoms among both fish processing workers and controls. Filleters had changed work tasks because of respiratory symptoms more often (Fisher's exact test, p = 0.02) than other fish processing workers. In conclusion the fish filleters and pressure sprayer users reported more adult asthma and cough with phlegm compared to the other fish processing workers and controls. The use of pressure sprayers must be reduced and machinery should be completely encased to reduce workers' exposure to bioaerosols and its effects on the respiratory tract.

Lung function and prevalence of respiratory symptoms in Norwegian crab processing workers

Background: Seafood processing workers have an increased risk of developing occupational asthma. This has not been studied among Norwegian crab processing workers, nor has the respiratory health of exposed workers been compared to a control group.

Objectives: Assessing the impact of working in the crab processing industry on workers’ respiratory health.

Design: A cross-sectional study of the respiratory health in two types of crab processing workers compared to a control group.

Methods: The study included 148 king crab (Paralithodes camtschaticus) workers, 70 edible crab (Cancer pagurus) workers and 215 controls. Workers answered a questionnaire and performed spirometry measurements. χ² and Fishers exact tests were performed on self-reported respiratory symptoms. Regression analyses and t-tests were used to assess lung function values.

Results: Self-reported respiratory symptoms were higher among crab processing workers compared to controls, and higher among king crab workers compared to edible crab workers. There was no significant difference between crab processing workers and controls in lung function measurements. Self-reported doctor-diagnosed asthma prevalence was highest in the control group.

Conclusions: Increased respiratory symptoms reported by crab processing workers were not reflected in impaired lung function values or asthma diagnose. We suggest a healthy worker effect among crab processing workers in Norway.

Analysis of workers' compensation disabling claims in Oregon's seafood preparation and packaging industry, 2007-2013

BACKGROUND

Few occupational health and safety studies have focused on the US seafood preparation and packaging industry, and none on Oregon's seafood industry.

METHODS

Oregon workers' compensation (WC) disabling claims data were analyzed. Oregon Employment Department and US Census Bureau data were used as denominators for rates.

RESULTS

During 2007-2013, there were 188 accepted disabling claims, with an average annual rate of 24 claims per 1000 workers. Men experienced a significantly higher rate (27.6 per 1000) than women. The most frequent incident characteristics and circumstances were: by nature-traumatic injuries to muscles, tendons, ligaments, joints (42%); by body part-upper extremities (44%); and by event-overexertion and bodily reaction (48%), and contact with objects and equipment (31%).

CONCLUSION

Analyzing WC disabling claims data provides important preliminary information for understanding workplace hazards to develop control strategies. Reducing traumatic and cumulative injury risk among seafood workers is paramount.

Respiratory symptoms, lung functions, and exhaled nitric oxide (FENO) in two types of fish processing workers: Russian trawler fishermen and Norwegian salmon industry workers

OBJECTIVE

Respiratory outcomes and work-related factors were studied in two seafood worker populations representing different occupational environments.

METHODS

Levels of fractional exhaled nitric oxide (FENO), spirometric values, prevalence of respiratory symptoms, and self-evaluated exposures were compared between 139 Norwegian salmon workers and 127 Russian trawler workers.

RESULTS

Increased odds ratios (ORs) of shortness of breath with wheezing and prolonged cough as general respiratory symptoms were found in salmon workers, while increased ORs of work-related dry cough and running nose were found in trawler fishermen. Both worker groups ranked "cold work environment," "use of disinfectants," and "contaminated indoor air" as the first, second, and third most important causes of work-related respiratory symptoms, respectively. Fractional exhaled nitric oxide levels were higher in asthmatic trawler workers compared to asthmatic salmon workers.

CONCLUSIONS

Respiratory symptoms commonly associated with obstructive airway diseases were more prevalent in salmon workers, while symptoms commonly associated with asthma and short-term effects of cold air exposure were more prevalent in trawler workers.

Differences in PAR-2 activating potential by king crab (Paralithodes camtschaticus), salmon (Salmo salar), and bovine (Bos taurus) trypsin

BACKGROUND

Salmon trypsin is shown to increase secretion of the pro-inflammatory cytokine interleukin (IL)-8 from human airway epithelial cells through activation of PAR-2. Secretion of IL-8 induced by king crab trypsin is observed in a different concentration range compared to salmon trypsin, and seems to be only partially related to PAR-2 activation. This report aim to identify differences in the molecular structure of king crab trypsin (Paralithodes camtschaticus) compared to salmon (Salmo salar) and bovine trypsin (Bos taurus) that might influence the ability to activate protease-activated receptor-2 (PAR-2).

RESULTS

During purification king crab trypsin displayed stronger binding capacity to the anionic column used in fast protein liquid chromatography compared to fish trypsins, and was identified as a slightly bigger molecule. Measurements of enzymatic activity yielded no obvious differences between the trypsins tested. Molecular modelling showed that king crab trypsin has a large area with strong negative electrostatic potential compared to the smaller negative areas in bovine and salmon trypsins. Bovine and salmon trypsins also displayed areas with strong positive electrostatic potential, a feature lacking in the king crab trypsin. Furthermore we have identified 3 divergent positions (Asp196, Arg244, and Tyr247) located near the substrate binding pocket of king crab trypsin that might affect the binding and cleavage of PAR-2.

CONCLUSION

These preliminary results indicate that electrostatic interactions could be of importance in binding, cleavage and subsequent activation of PAR-2.

An analysis of the respiratory health status among seafarers in the Russian trawler and merchant fleets

OBJECTIVES

Trawler fishermen and merchant seafarers have tough working conditions. While workers in both occupations are exposed to a challenging environment, trawler fishermen are also engaged in onboard fish processing, which is considered to be additional exposure. The aim of the present study was to characterize respiratory health status in both groups of seamen.

METHODS

In total 127 trawler fishermen and 118 merchant seafarers were enrolled during their regular medical health examinations. The study protocol comprised a standardized questionnaire, lung function test and measurements of fractional nitric oxide concentrations (FE(NO) ) in exhaled air.

RESULTS

Doctor-diagnosed asthma was reported only by trawler fishermen (3.9%, P < 0.05, Pearson Chi-square test). Adjusted odds ratios (OR) of respiratory symptoms were more often elevated in trawler fishermen compared to merchant seafarers. Trawler fishermen had reduced spirometric parameters: FEV(1) % of predicted values (adjusted β: -5.28, 95%CI: -9.28 to -1.27), FVC % of predicted values (adjusted β: -5.21, 95%CI: -9.25 to -1.17). Increased OR of the work-related cough with phlegm (OR: 6.6, 95% CI: 1.8-21.9), running nose (OR: 3.0, 95%CI: 1.2-7.7), and frequent sneezing (OR: 3.4, 95%CI: 1.0-12.7) were found among those trawler workers whose work tasks included filleting of fish. FE(NO) levels were not significantly different between trawler and merchant seamen.

CONCLUSIONS

The present study indicated that trawler fishermen exhibited impaired lung function and were more likely to have asthma. The environment of the onboard factories where fishermen fillet fish is suggested as a risk factor for work-related respiratory symptoms.