Inflammatory potential of dust from waste handling facilities measured as IL-8 secretion from lung epithelial cells in vitro

Abstract

Objectives: Organic dust contains several different components which may cause pulmonary effects, and many health problems have been associated with the collection and recycling of organic waste. It is often difficult to obtain a precise measurement of the exposure to each component in dust, and organic dust samples obtained from different workplaces may vary profoundly in composition. The aim of this study was to evaluate the inflammatory potential of dust from different waste handling plants. Furthermore, we set out to investigate the role of endotoxin in the inflammatory potential of dust.

Methods: Dust samples were obtained from four incineration plants, three samples from a plant sorting household waste, five paper-sorting plants, two mail centres, four bottle-sorting plants, and two combined paper-sorting and composting plants. The samples were tested in a bioassay with the lung epithelial cell line A549. Cells were stimulated for 24h with dust samples at six concentrations, and subsequently the interleukin 8 (IL-8) secretion into the growth medium was measured. The initial slope of the dose response curves was used to calculate the potency factor (PF) of the dust samples, and correction against positive control samples was used to reduce day-to-day variation. The concentration of endotoxin in the dust samples was measured by the limulus amebocyte lysate (LAL) assay.

Results: The inflammatory potential of the dust samples for dust from the paper- and mail-sorting plants showed a significantly lower PF as compared with dust from the plants handling mixed household waste. A significantly lower PF for the dust samples from the bottle-sorting plants (excluding one outlier plant) compared with dust from the plants handling mixed household waste was also found. No correlation was observed between the PF and the concentration of endotoxin in the samples.

Conclusion: The PFs obtained seem to reflect the material handled, with mixed household waste generating organic dust with the highest inflammatory potentials.