On September 18, 2018, the National Institute for Occupational Safety and Health (NIOSH) published a Federal Register notice announcing the availability of a draft document entitled Current Intelligence Bulletin: Health Effects of Occupational Exposure to Silver Nanomaterials. As reported in our January 22, 2016, blog item, NIOSH published a draft Current Intelligence Bulletin (CIB) on silver nanomaterials on January 21, 2016. According to the notice, the revised draft CIB provides an updated scientific literature review of information pertaining to occupational exposure to silver nanomaterials. The literature review includes studies on the toxicological effects of exposure to silver nanomaterials in experimental animal and cellular systems, the effect of particle size and other properties on the toxicological effects of silver, and NIOSH recommendations on the measurement and control of occupational exposures to silver and silver nanomaterials. NIOSH assessed the potential health risks of occupational exposure to silver nanomaterials by evaluating the scientific literature. The notice states that studies in animals “have shown adverse lung and liver effects associated with exposure to silver nanoparticles.” Based on an assessment of these data, NIOSH developed a recommended exposure limit (REL) for silver nanoparticles (<100 nanometers (nm) primary particle size) of 0.9 micrograms per cubic meter (μg/m3) as an airborne respirable eight-hour time-weighted average (TWA) concentration. The draft REL would apply to processes that produce or use silver nanomaterials. In addition, NIOSH continues to recommend a REL of 10 μg/m3 for total silver (metal dust, fume, and soluble compounds, as Ag). NIOSH further recommends the use of workplace exposure assessments, engineering controls, safe work procedures, training and education, and established medical surveillance approaches to prevent potential adverse health effects from exposure to silver nanomaterials. NIOSH proposes research needs to fill remaining data gaps on the potential adverse health effects of occupational exposure to silver nanomaterials. The purpose of the public review of the draft CIB is to obtain comments on whether it (1) adequately and clearly describes the scientific literature on the potential adverse health effects of silver nanomaterials, and (2) demonstrates that the NIOSH recommendations on occupational exposure to silver nanomaterials are consistent with current scientific knowledge. Comments on the draft CIB are due November 30, 2018.
NIOSH will hold a public online meeting on October 30, 2018, 1:00 p.m.-4:30 p.m. (ET), or until the last public commenter has spoken, whichever occurs first. NIOSH states that the public online meeting will be a web-based event available only by remote access. According to the notice, special emphasis will be placed on discussion of the following questions for reviewers:
- Does the draft CIB accurately identify and characterize the health hazards of exposures to silver and silver nanomaterials based on the available scientific literature?
- Are the risk assessment and dosimetry modeling methods presented in the draft CIB consistent with current scientific knowledge and practice?
- Is the relationship between exposure to silver nanomaterials and biological activity (toxicity) accurately portrayed in the draft CIB?
- Is the available scientific evidence fully described regarding the human health relevance of the adverse health endpoints observed in rats associated with exposure to silver nanomaterials?
- Is the proposed REL well-supported by the scientific data presented in the draft CIB?
- Are the sampling and analytical methods proposed for silver nanomaterials adequate to measure worker exposure?
- Are the recommended strategies for controlling exposure to silver and silver nanomaterials (e.g., engineering controls, work practices, personal protective equipment) reasonable?
- Are the important data gaps and future research needs complete and clearly described?
NIOSH has posted the following materials in Docket ID CDC-2016-0001: