Society is facing a variety of challenges in environmental risk assessment (ERA): growing concerns about the effects of multiple stressors (both chemical and non-chemical); risks associated with exposure to complex mixtures; and demands to quantify local site-specific risks. At the same time, risk assessors are seeking to provide a more efficient framework on which to address these emerging problems and questions in a manner that reduces cost and the use of animals.
Recently there have been a number of studies that have aimed at demonstrating that chemicals that interact with biological systems through relatively weak and reversible hydrophobic interactions to cause non-specific baseline toxicity, or ‘narcosis’, are associated with a narrow range of internal body concentrations (2-8 mmol/kg) and chemical activities (0.1 to 0.001), [1, 2].
This observation has the potential to dramatically improve how we might do risk assessment for chemicals identified as baseline toxicants. Whereby, the risk assessment can be based on ensuring that the predicted environmental concentration is <1% of the solubility of the chemical. However, as highlighted within a recent ECETOC task force report, in which an extensive set of existing data provided a proof of concept for the relationship between chemical activity and toxicity for baseline toxicants, concerns were raised regarding the lack of high quality chronic aquatic toxicity data, and the data available for assessing the relationship of chemical activity with chemicals with other modes of action .
The project’s objectives are to evaluate a wide range of data and databases for the potential to expand the domain of applicability of chemical activity. In particular:
- Expand the domain of applicability of chemical activity using existing data sets, including but not limited to other, i.e. non-baseline toxicity modes of action, other endpoints, in vitro data.
- In the absence of high quality data, are there approaches/strategies for utilizing acute and chronic data of lesser quality.
- Determine if MoA and chemical activities cluster in large in vitro data sets (e.g. USEPA ToxCast).
Download here the full version of the RfP LRI-ECO30.