The characterisation and management of workers’ exposure to dust, endotoxin and β-(1-3) Glucan at large-scale composting facilities.

Abstract

Commercial composting is becoming more prevalent in the UK as biodegradable municipal waste is being diverted from landfill. Exposure to the organisms actively grown during the composting of waste are known to cause adverse effects on respiratory health when these organisms, or fragments of these organisms, become airborne forming a ‘bioaerosol’. The aim of this Thesis is to characterise compost workers’ exposure levels to bioaerosols by measuring their exposure to dust, endotoxin and β-(1-3) glucan and to use this exposure data to inform the development of evidence-based risk assessment and risk mitigation measures. In general, workers’ exposure to dust was low in the four sites studied but there was extensive variation in personal exposure levels. The inhalable fraction was found to be the predominant fraction of concern. Manual sorting and the screening of final product gave rise to high exposures to inhalable dust on occasion. Despite dust levels being generally low, workers’ exposures to endotoxin and to a lesser extent β-(1-3) glucan were elevated and workers were exposed to levels thought to be related to respiratory symptoms and disease. Any activities involving the movement of waste resulted in elevated levels of endotoxin and β-(1-3) glucan at all four sites investigated in this study. Vehicle operators’ exposure levels were high and a multi-faceted strategy is needed to reduce exposure levels to an acceptable level. Currently, no Workplace Exposure Limits or agreed dose-response estimates exist in the UK to manage workers’ exposure levels. Consequently the risk to worker’s health is difficult to characterise. The COSHH Regulations require employers to reduce compost workers’ exposure levels to bioaerosols ‘so far as is reasonably practical’. This study discusses the need for site-specific, task-specific risk assessments to be conducted and that robust risk mitigation measures are required to minimise the impact on compost workers health.