Scientific and practical considerations for the development of occupational exposure limits (OELs) for chemical substances

Acute pulmonary dose–responses to inhaled multi-walled carbon nanotubes

“…Using the MWCNT MMAD = 1.5 mm, minute ventilation of 20 L/min for a person performing light work (Galer et al 1992), deposition fraction of 30% (Phalen 1984) and human alveolar epithelium surface area of 102 m 2 (Stone et al 1992), approximate human lung burden per month for a workplace MWCNT exposure of 106 or 400 mg/m 3 (Han et al 2008;Lee et al 2010) would be 60 and 226 mg MWCNT/m 2 alveolar epithelium, respectively. Thus, 7 mg MWCNT lung burden in mouse approximates human deposition for a person performing light work for 1-2 months, while the 31 mg MWCNT lung burden in mice approximates human deposition for a person performing light work for 3-10 months.…”

Pulmonary Toxicity of Intratracheally Instilled Multiwall Carbon Nanotubes in Male Fischer 344 Rats

“…No data for CNT concentrations in workplace air have been reported to date, except for the measurement 44) of the peak airborne concentration of respirable dust during handling of SWCNT in a real workplace, 53 m g/m 3 by Maynard et al Assuming that a worker would breathe air laden with MWCNT aerosol at an average of 53 m g/m 3 during an 8-h shift of light work with a minute ventilation of 0.02 m 3 /min 45) , and assuming that 11% of respirable MWCNT aerosol with an aerodynamic diameter of 0.70 m m would be deposited in the alveolar area 46) , 56 m g of MWCNT would be to deposited on the worker's alveolar epithelial surface area. Assuming even distribution of 56 m g of inhaled MWCNT and 40 m g of intratracheally instilled MWCNT over the alveolar surface area of human and rat lungs, respectively, and normalizing to the equivalent alveolar surface area in the human (143 m 2 /lung) and rat (0.392 m 2 /lung) from the published morphometric analysis 47) , the amount of MWCNT deposited on the unit alveolar surface area would be 0.39 m g/m 2 for humans and 102 m g/m 2 for rats.…”

A semiquantitative method for selection of safety factors in establishing OELs for pharmaceutical compounds

“…A similar, though perhaps more simplified, approach to OEL setting is presented by Galer et al (1992):…”

“…While there continues to be a dearth of published literature on this topic, occupational toxicologists from many of the pharmaceutical companies operating in the U.S. have worked together to develop common methodology for an approach to OEL setting. Indeed, one of the products of the annual Occupational Toxicology Roundtable, attended primarily by occupational toxicologists and industrial hygienists from within the pharmaceutical industry, is the paper by Galer et al (1992), discussed below, that discusses scientific and practical considerations for Occupational Exposure Limit (OEL) setting.…”