OCCUPATIONAL ALLERGY AND ASTHMA AMONG FISH PROCESSING WORKERS IN SOUTH AFRICA

Abstract

ISEE-226 Introduction: The South African seafood industry employs over 28,000 mainly seasonal women workers involved predominantly in bony fish processing activities. Aim: The aim of this study was to determine the risk of developing work-related asthma during fish processing. Methods: A cross-sectional study of 594 workers in two factories involved in fish canning (pilchard) and fishmeal processing (anchovy and pilchard), was undertaken. All workers were evaluated using interviewer-administered questionnaires, skin prick tests with common airborne and fish allergen extracts, and pulmonary function including methacholine challenge tests. Time-integrated environmental sampling using a thoracic fraction sampler collected 198 personal samples for total particulate mass, protein and specific fish antigen determinations. A novel ELISA-inhibition assay using polyclonal antibodies was developed for this purpose. Multivariate logistic and Cox proportional hazards models were used in the data analysis. Results: Results of environmental samples demonstrated a wide variation in mean (arithmetic) airborne concentrations of thoracic particulate 0.61 mg/m3 (0–11.3), total protein 0.89 μg/m3 (0–11.5), pilchard antigen 150 ng/m3 (0–15,973) and anchovy antigen 552 ng/m3 (0–75,748) levels. All four exposure metrics were consistently elevated for fishmeal production. Ambient pilchard and anchovy antigen levels were more strongly correlated with each other than total thoracic particulate and fish antigen concentrations. Common work-related symptoms reported included ocular-nasal (26%), asthma (16%) and skin symptoms (14%). The prevalence of atopy (positive skin prick test to one or more common allergens) was 36% with 7% sensitized to fish and 26% having non-specific bronchial hyperresponsiveness. The prevalence of fish-related rhino-conjunctivitis was slightly higher (2.6%) than probable occupational asthma (1.8%) and urticaria (1%). Atopy and smoking were important host factors related to fish sensitization. Workers with recurrent skin symptoms were twice as likely to be sensitized to fish. In Cox proportional hazards models, having work-related asthma symptoms was associated with a two-fold increased odds of being exposed to pilchard antigen concentrations >30 ng/m3 at the time when symptoms occurred (OR:2.25, CI:1.06–4.75). Conclusion: Fish processing (canning/fishmeal production) workers are at increased risk of developing work-related asthma symptoms by inhaling aerosols containing fish allergens. This study demonstrates the role of international collaboration and funding in promoting the conduct of state-of-the-art studies in Southern Africa, which can inform interventions to improve the health of workers.