117 Optimization of the Measurement Method for Airborne Endotoxins in Workplace Atmospheres: a Laboratory and Field Study

Abstract

Abstract Endotoxins are lipopolysaccharides present in the outer membrane of most Gram-negative bacteria. They can become airborne by working tasks, techniques and processes that generate aerosols from materials contaminated by these microorganisms and can cause harmful effects on the health of workers by inhalation. Since 2005, INRS has been proposing a method for measuring endotoxins, which use a 2 L/min closed-face cassette sampling and an analysis by chromogenic LAL assay, mainly following EN 14031 standard. However, the evolution of knowledge and the lack of some validation data led to new experimental investigations in order to optimize this method: optimization of the sampling (filters type) and the extraction protocol (liquid volume, duration, methodology) as well as the influence of sample storage have been studied. A bubbler-type generator was used to produce a bioaerosol from a mixture of three bacteria to obtain controlled concentrations of 50 to 10000 EU/m3. These laboratory tests confirmed a better recovery of endotoxins when extraction is carried out directly in the cassette and let possible to fix the volume (5 mL) and the duration (20 min) of elution. PVC filters appear to result in lower endotoxins recovery compared to fiberglass, PTFE or PC filters. Additional field tests were done in different workplaces as livestock farm (pig, cow), grain processing, composting and wastewater treatment plants. Comparison of filters results in these occupational environments as well as the influence of samples storage at room temperature during 8 days will be discussed.