Question

What are some problems associated with determining the dose of airborne nanomaterials in a worker’s breathing zone?

Answer 1

Engineered (manufactured) nanomaterials have at least one dimension between approximately 1 nm and 100 nm, and are manufactured to have specific properties or composition. While there are hundreds of manufactured nanomaterials in existence, there are only two Australian exposure standards relating to specific nanomaterials. The Workplace Exposure Standard for carbon black is 3 mg/m3 (8-hour TWA) and the Workplace Exposure Standard for fumed silica is 2 mg/m3 (8-hour TWA). Exposure to nanomaterials should be eliminated or minimised so far as reasonably practicable through containment of materials, local exhaust ventilation (LEV) and/or work processes.

investigators and organizations have been concerned about the same effects and have recommended occupational exposure limits (OELs) for CNT within the range of 1–50 µg/m3 [Nanocyl 2009; Aschberger et al. 2010; Pauluhn 2010b; Nakanishi (ed) 2011a,b]. The relative consistency in these proposed OELs demonstrates the need to manage CNT/CNF as a new and more active form of carbon. To put this in perspective, since there is no Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for CNT/CNF, the PEL for graphite (5,000 µg/m3 ) or carbon black (3,500 µg/m3 ) [NIOSH 2007] might inappropriately be applied as a guide to control worker exposures to CNT/CNF. Based on the information presented in this document, the PELs for graphite or carbon black would not protect workers exposed to CNT/CNF.