Commercially manufactured engineered nanomaterials for environmental and health studies: important insights provided by independent characterization.

Environmental and health studies on nanomaterials are appearing in the literature at a rapid pace. These studies will address important issues related to the environmental health and safety (EHS) of nanomaterials. As noted in many recent workshop and agency reports, studies devoted toward the environmental fate and transport, nanomaterial-biological interactions, toxicity, and overall risk assessment of nanomaterials should have nanomaterial characterization as a central component of the study design. This aspect of the study design is necessary so that risks associated with nanomaterials can be fully understood and related to specific material properties. For studies that use commercially manufactured nanomaterials, the company often provides characterization data (e.g., chemical composition, phase, and size) of the purchased materials. One question is, how good are these data? Another is, what methods of analysis are used to characterize the properties of commercial nanomaterials? In the present study, some examples are presented that show marked differences between independent characterization of commercially manufactured nanomaterials and that provided by the company. Furthermore, information provided by the manufacturer may be incomplete and nonrepresentative of the entire sample and, in some cases, the information can, in fact, be wrong. Thus, the current study demonstrates an important need for independent characterization data in EHS studies of purchased materials.