Exposure and Risk Assessment Strategies for Managing Nanomaterials
William Cyrs; Brooke Tvermoes; Marisa Kreider
(1) Cardno ChemRisk, San Francisco, CA; 2) IBM Corporate Environmental Affairs, Durham, NC; 3) Cardno ChemRisk, Pittsburgh, PA )
Engineered nanomaterials (ENMs) are an important technology to the semiconductor industry, but represent a challenge for occupational health professionals (OHP) in evaluating worker exposure and risk. Such characterization is critical not only to ensure worker health, but also to aid in the establishment of evidence-based exposure guidelines for these materials. In this three-part workshop, we will explore strategies for exposure and risk assessment for ENMs that aid in decision-making regarding new material development and implementation of controls. In the first part, we will present specific experience and challenges from an industry representative as it relates to nanomaterial exposure and risk assessment. In the second part, we will explore available techniques for exposure assessment. Specific exposure assessment methods used to evaluate exposure to ENMs in semiconductor manufacturing primarily include number concentration measurement by real-time instrumentation, chemical identification using filter-based sampling coupled with electron microscopy and energy-dispersive spectroscopy (EM-EDS), and mass concentration measurement. However, there is still no standard methodology, and the methods described in the literature use multiple equipment and are costly and time-consuming. We will provide an overview of major available exposure assessment techniques for nanoparticles, including strengths and weaknesses of each technique, and will highlight a novel method that combines the use of an electrical low-pressure impactor with offline analysis by EM-EDS. Equipped with knowledge of these methods, OHPs should be able to design an efficient exposure assessment strategy that is time- and cost-saving and can be used until standardized and inexpensive methods become available. In the third part of this presentation, we will present a hierarchical human health risk ranking framework, which can be used to identify and prioritize hazards and health risk scenarios involving nanomaterials. This framework considers characteristics of the material and its use relating to exposure probability as well as physiochemical properties and toxicology data relating to hazard to score potential risk associated with a given material. The intent of this framework is to provide a streamlined method to identify and prioritize risk assessment, toxicity testing, and exposure control efforts for ENM use in a variety of scenarios and lifecycle stages. This presentation will review the framework and an example of how to evaluate ENMs, using two exemplar carbon-based materials. This workshop will provide attendees with tools to aid in managing worker health and safety as it relates to use of nanomaterials in the workplace.