On October 21, 2013, Particle and Fibre Toxicology posted an article entitled “Carbon nanotube dosimetry: from workplace exposure assessment to inhalation toxicology.” The authors, who are affiliated with the National Institute for Occupational Safety and Health (NIOSH), note that there are currently no known end-point effects in humans following carbon nanotube (CNT) exposure, leading to extrapolation from rodent studies. The purpose of the study was to determine how realistic U.S. workplace exposures to CNTs relate to animal studies.
The study states that its goal “was to expose animals to a high dose that would cause significant inflammation with histological findings and then a low dose to serve as a no observable effect level. This design will serve as a reference for detailed molecular analysis, pulmonary pathology, systemic inflammation, and evaluation of cardiovascular dysfunction at human relevant exposures.”
The abstract states that the findings “showed a limited pulmonary inflammatory potential of MWCNT at levels corresponding to the average inhalable elemental carbon concentrations observed in U.S.-based CNT facilities and estimates suggest considerable years of exposure are necessary for significant pathology to occur at that level.” The conclusion itself states: “It is clear from toxicological evaluations that MWCNT have a relatively high hazard when compared to other materials. These hazards may include fibrosis, promotion of lung tumors, cardiovascular dysfunction, and pulmonary and systemic inflammation. The present findings show that limiting cumulative exposures is imperative to reducing adverse effects.”