Environmental exposure characterization of fish processing workers

Aerosolization of seafood and subsequent inhalation, during processing is a potential high-risk activity for allergic respiratory disease.

To quantify total thoracic particulate, protein concentration and specific fish (pilchard, anchovy) antigen concentrations in fish processing plants; to determine the correlation between these exposure metrics; and to identify the major determinants of variability and the optimal grouping strategies for establishing dose-response relationships for fish antigen exposures.

Exposure assessments were conducted on randomly selected individuals within each of the identified 'exposure groups' (EGs) in two fish processing factories. Personal time-integrated sampling was conducted with a thoracic fraction sampler and analysed for particulate mass, total protein and specific fish antigens. Exposure metrics were developed on the basis of individually measured exposures and average levels of these personal samples within EGs. The main components of the exposure variability were determined using ANOVA techniques.

A total of 198 full-shift personal aerosol samples were collected and analysed. Twenty-two percent of the samples were below the limit of detection (LOD) for pilchard and 23% for anchovy assays. Personal sampling revealed wide variations across EGs in arithmetic mean concentrations of thoracic particulate 0.61 mg m(-3) (range: LOD-11.3), total protein 0.89 microg m(-3) (LOD-11.5), pilchard antigen 150 ng m(-3) (LOD-15 973) and anchovy antigen 552 ng m(-3) (LOD-75 748) levels. The fishmeal loading and bagging sections of both plants showed consistently high thoracic particulate mass (0.811-2.714 mg m(-3)), total protein (0.185-1.855 microg m(-3)), pilchard antigen (538-3288 ng m(-3)) and anchovy antigen (1708-15 431 ng m(-3)). The a priori strategy that grouped workers according to EGs produced reasonably satisfactory summary exposure metric statistics. An alternative grouping strategy based on department revealed comparable elasticity (exposure contrast). While the correlation between the log-transformed thoracic particulate mass and fish antigen concentrations were generally modest (Pearson's r = 0.32-0.35, P < 0.001), a high correlation was found between pilchard and anchovy antigen concentrations (Pearson's r = 0.71, P < 0.001). Models using factory and department grouping strategies accounted for a significant portion of the variability (adjusted r(2) = 0.18, P = 0.043) in pilchard antigen levels. Grouping strategies using a combination of factory and department yielded the highest degree of elasticity for thoracic particulate (0.38) and pilchard antigen (0.42) levels.

Workers involved in bony fish processing are at risk of inhaling aerosols containing pilchard and anchovy fish antigens. Antigen exposures are highest during fishmeal production and bagging. Grouping strategies based on department and factory may provide a more efficient approach than a priori classification of EGs for evaluating fish antigen exposures.