Endotoxin as modifier of particulate matter toxicity: a review of the literature

It is well known that particulate matter (PM) and endotoxin are able to trigger inflammatory responses in the lung. Most studies have focused on the components separately and on the identification of chemical components associated with PM. However, since biological components may represent around 20% of airborne PM, and endotoxin may reach concentrations as high as 30 EU/mg, recent studies have focused attention on the characterization of endotoxin present in PM and health effects. Most of the literature has suggested that endotoxin adsorbed in PM is able to elicit immunological responses associated with increase in pro-inflammatory cytokine expression. The aim of this paper is to provide an up to date review of the findings involving toxicity effects of endotoxin associated with PM.