Occupational endotoxin exposure and health effects

Lipopolysaccharide (LPS), also termed endotoxin, is an integral structural component of the outer membrane of Gram-negative bacteria and has been a focus of bioaerosol research for many years. Endotoxin is nearly ubiquitous in the environment; however, exposure at specific workplaces, such as waste collecting, livestock farming, agriculture, the textile industry has been associated with adverse health effects. The aim of this review is to summarize studies published in the last 10 years on endotoxin measurement and health effects due to endotoxin in occupational settings. The search was mainly performed using MEDLINE (Pubmed), focusing on publications related to the determination of endotoxin, inhalative occupational endotoxin exposure, and health effects. The review shows that despite the well-established methods available to measure endotoxin, a global comparison of studies still remains difficult because the details of sampling strategies and exposure assessment are variable and depend on the specific workplace situation. Thus, health-based threshold limit values still cannot be derived on the basis of available data. Since endotoxin is only one component in a heterogeneous bioaerosol mixture, the question remains open on how to evaluate and record the additional effects of the other components. In particular, there is a lack of intervention studies investigating the effectiveness of protective measures with respect to health outcome. In addition, the studies selected in this review show a wide range of endotoxin exposure, even within one industry or sector. The level of exposure seems to depend more on the specific task performed and the way it was performed rather than on the profession or industry itself. The identification of hot spots of exposure, as well as methods of communication on hazards and possible protective measures, seem to remain important tasks in occupational health protection.