Tiered guidance for risk-informed environmental health and safety testing of nanotechnologies

Provided the rapid emergence of novel technologies containing engineered nanomaterials, there is a need to better understand the potential environmental, health, and safety effects of nanotechnologies before wide-scale deployment. However, the unique properties of nanomaterials and uncertainty regarding applicable test methods have led to a lack of consensus regarding the collection and evaluation of data related to hazard and exposure potentials. Often, overly conservative approaches to characterization and data collection result in prolonged, unfocused, or irrelevant testing, which increases costs and delays deployment. In this paper, we provide a novel testing guidance framework for determining whether a nanotechnology has the potential to release material with nano-specific parameters that pose a risk to humans or the environment. The framework considers methods to categorize nanotechnologies by their structure and within their relevant-use scenarios to inform testing in a time- and resource-limited reality. Based on the precedent of dredged sediment testing, a five-tiered approach is proposed in which opportunities are presented to conclude testing once sufficient risk-related information has been collected, or that the technology in question does not require nano-specific scrutiny. A series of screening stages are suggested, covering relevant aspects including size, surface area, distribution, unique behaviors, and release potential. The tiered, adaptive guidance approach allows users to concentrate on collecting the most relevant data, thus accelerating technology deployment while minimizing risk.