Technical Approach

Previously, incomplete toxicity data have been used to develop regulatory values that, once promulgated, become difficult to update even when additional, focused data are provided. This approach has resulted in the use of uncertainty factors, often several orders of magnitude in scope, applied to toxicity benchmarks by regulators to protect human health and the environment. For example, the lack of toxicity data has resulted in exceedingly low drinking water criteria for RDX, which has closed, curtailed, and restricted range operations. Thus, an assemblage of toxicity information is needed that can reduce the use and magnitude of uncertainty factors prior to the promulgation of regulatory benchmarks. The in vivo/in vitro approach in this project is designed to fill specific data gaps that will provide insights regarding reproductive and developmental toxicity and endocrine disruption and will refine no-effect levels and generate benchmark toxicity values for mammals, birds, and amphibians exposed to NTO and DNAN. The development of benchmark values and mode of action information will limit the use of default uncertainty factors by regulatory agencies for developing environmental cleanup criteria.