Page:Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes.pdf/33

 Store dispersible nanomaterials, whether suspended in liquids or in a dry particle form, in closed (tightly sealed) containers whenever possible. (8) Ensure work areas and designated equipment (e.g., balance) are cleaned at the end of each work shift, at a minimum, using either a HEPA-filtered vacuum cleaner or wet wiping methods (where the use of liquid does not create additional safety hazards). Dry sweeping (i.e., using a broom) or compressed air should not be used to clean work areas. Cleanup should be conducted in a manner that prevents worker contact with wastes. (9) Dispose of all waste material in compliance with all applicable federal, state, and local regulations. (10) Avoid storing and consuming food or beverages in workplaces where nanomaterials are handled [NIOSH 2009a].

PPE (e.g., respirators, gloves, protective clothing) is the least desired option for controlling worker exposures to hazardous substances. PPE is used when engineering and administrative controls are not feasible or effective in reducing exposures to acceptable levels or while controls are being implemented. It is the last line of defense after engineering controls, work practices, and administrative controls. A program that addresses the hazards present, employee training, and PPE selection, use, and maintenance should be in place when PPE is used.

2.5.1 Skin Protection

Nanomaterials have been shown to accumulate in hair follicles, and quantum dots have been shown to penetrate the skin into the dermis [Smijs and Bouwstra 2010]. Flexing the skin may enhance skin penetration [Smijs and Bouwstra 2010; Tinkle et al. 2003]. Woskie [2010] recommends wearing gloves, gauntlets, and laboratory clothing or coats when working with nanoparticles. Other studies of specifically engineered nanomaterials have resulted in the material not penetrating beyond the stratum corneum. Of importance is to establish a barrier between the potentially hazardous material and the skin.

Air-tight polyethylene was found to be more resistant to nanoparticle penetration by diffusion than cotton or polyester; gloves made of latex, neoprene, or nitrile resisted nanoparticle penetration “during exposure of a few minutes” [Woskie 2010]. Proper selection of gloves should take into account the resistance of the glove to the nanomaterial and any other chemicals or liquids with which the hands may come into contact. Gloves should be changed whenever they show visible signs of wear or contamination. Gao et al. [2011] studied nano- and submicron-size (30–500 nm) iron oxide particle penetration through some protective clothing materials. They found that particle penetration increased with increasing wind velocity and increasing particle size. Results from the study indicated that the MPPS for protective clothing materials tested was found to be about 300 to 500 nm, compared to an MPPS for N-95 respirators of 50 nm.

2.5.2 Respiratory Protection

Respiratory protection is used to reduce worker exposures to acceptable levels in the absence of effective engineering controls, during the installation or maintenance of engineering 18

Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes