Human and animal evidence supports lower occupational exposure limits for poorly-soluble respirable particles. Letter to the editor re: 'Low-toxicity dusts: current exposure guidelines are not sufficiently protective' by Cherrie, Brosseau, Hay and Donaldson.
Kuempel ED; Attfield MD; Stayner LT; Castranova V
Ann Occup Hyg 2014 Nov; 58(9):1205-1208
We commend the overall evaluation by Cherrie et al. (2013) of the current occupational exposure limits (OELs) for respirable poorly-soluble low toxicity (PSLT) particles. As described in that paper, the epidemiological studies provide compelling evidence that exposure to PSLT at the current OELs has been associated with adverse health effects, including pulmonary fibrosis and lung function deficits. In contrast to Cherrie et al. (2013), we discuss here that the chronic inhalation studies in animals also provide evidence of the adverse pulmonary effects of PSLT. Cherrie et al. view has been accepted by some regulatory institutions. For example, in the USA, the regulatory exposure limit for respirable coal mine dust is to be reduced from 2 mg m-3 as a multi-shift average concentration to 1.5 mg m-3 as a single-shift (8-hr time-weighted average) concentration, starting in August 2016 (MSHA, 2014). In addition, the rat studies provide supporting evidence with qualitatively and quantitatively consistent findings to those in the human studies. Yet, more research is needed to reduce uncertainty about the rodent dose-response models compared to humans. Such evidence is important for risk assessment and OEL development of other types of airborne particles (e.g., nanoparticles) for which sufficient human data may not be available.
Exposure-limits; Toxicology; Epidemiology; Health-hazards; Particulates; Respirable-dust; Occupational-exposure; Permissible-concentration-limits; Respiratory-system-disorders; Pulmonary-system-disorders; Lung-disorders; Laboratory-animals; Inhalation-studies; Chronic-exposure; Chronic-inflammation; Humans; Dose-response; Surveillance
Eileen D. Kuemple, National Institute for Occupational Safety and Health, Education and Information Division, 1090 Tusculum Avenue, Cincinnati, OH, 45226 USA
EID; DRDS; HELD
Annals of Occupational Hygiene