Frequently Asked Questions

In USEtox, persistent and bioaccumulative chemicals are considered and included in the chemical database. These compounds typically have large characterization factors due to the significant potential for exposure through multiple pathways. If such substances are moderately soluble, this will yield lower eco-exposure factors. However, due to the generally large fate factors (i.e. long persistence in the environment) and higher bioaccumulation potential (reflected in high effect factors), overall characterization factors for such substances are typically large as compared to other chemicals.

For considering consumer exposure, a near-field/far-field modeling framework was developed and is available (Fantke et al. 2016) that was recommended in the global UNEP-SETAC GLAM effort to be implemented in USEtox’ next update (see Pellston report 2019). This framework has already been applied in various case studies, is fully mass balance based and aligned with USEtox, which allows to combine impacts from product constituents with impacts from emissions along product life cycles.

For human toxicity, cancer and non-cancer health impacts are considered separately as indicators of disability in USEtox. Cancer effects rely to a large extent on TD50 (the dose eliciting a 50% population response) values that indicate potency to develop a tumor. Cancer is one type of tumor-related disease outcome and strongly associated with mutagenic properties of a chemical. As for reproductive toxic effects, these are captured in non-cancer effect factors whenever underlying reproductive toxic test data are available. Since all underlying available test data per chemical should be used to derive USEtox effect factors from the lowest converted human lifetime dose per exposure route, all underlying effects are considered in USEtox.

USEtox currently applies a fixed acute-to-chronic ratio of 2 as a statistical average across several chemicals (see Jolliet et al. 2003) and is confirmed by current, much broader studies (Posthuma et al. 2019, Aurisano et al. 2019). This fixed ratio does not account for variability across chemicals and species.