No abstract

Endotoxin has established health impacts and may be a potential confounding factor in toxicity studies of engineered nanomaterials (ENM). We aimed to characterize endotoxin contamination for a representative set of carbon-based ENM. The established method for quantifying endotoxin relies on its activity in a complex biochemical assay system. Because of their physical and chemical properties, measurement of endotoxin associated with many ENM presents non-trivial technical challenges. We have made progress in identifying and implementing methods for ENM analysis with respect to endotoxin content, revealing varying levels of endotoxin contamination in the ENM examined here. The physical association of ENM and endotoxin and their shared physiological effects suggest the possibility that contaminating endotoxin may contribute to the toxicity that is ascribed to ENM. We found in this small number of samples that endotoxin levels were not related to type of ENM or surface area but may be introduced randomly during manufacture.

Monitoring of ambient bioaerosol concentrations through the characterization of outdoor particulate matter (PM) has only been performed on a limited basis in North Carolina (NC) and was the goal of this research. Ambient samples of PM 2.5 (fine) and PM 10−2.5 (coarse) were collected for a six-month period and analyzed for mold, endotoxins and protein. PM 2.5 and PM 10−2.5 concentrations of these bioaerosols were reported as a function of PM mass, as well as volume of air sampled. The mass of PM 2.5 was almost twice that of the PM 10−2.5 ; however, the protein and endotoxin masses were greater in the coarse than the fine PM indicating an enrichment in the coarse PM. The protein and mold results demonstrated a seasonal pattern, both being higher in the summer than in the winter. Except for an occasional excursion, the endotoxin data remained fairly constant throughout the six months of the study.