The Organization for Economic Cooperation and Development (OECD) posted a new publication in its Series on the Safety of Manufactured Nanomaterials, Preliminary Guidance Notes on Nanomaterials: Interspecies Variability Factors in Human Health Risk Assessment. The report includes the following recommendations for further work:
- The Expert Opinion prepared in support of the project noted a general lack of availability of data from repeated-dose toxicity studies in different species. In particular, studies of extended duration such as 90-day subchronic or chronic toxicity studies were only available for a minor part of the analyzed nanomaterials and routes of exposures. The majority of the compiled studies did not determine a no-observed-adverse-effect level (NOAEL) or a lowest-observed-adverse-effect level (LOAEL), and only few studies determined both. Further testing should be considered on a set of representative materials, with identical materials tested under comparable exposure conditions for various exposure times in different species; and
- Physiologically-based models are receiving increased attention in human health risk assessment. With the available data on lung burden following inhalation exposure to nanomaterials, a useful comparison of measured vs. predicted data has been possible in this project for rats, suggesting that further refinement of the multiple path particle dosimetry (MPPD) model is required before it can be applied to (sub)chronic scenarios. Unfortunately, corresponding information has not been available for humans, preventing comparisons between rats and humans.