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Addressing endocrine-related human health effects in life cycle impact assessment (LCIA)
Citation:
Emara, Y., P. Fantke, R. Judson, AND M. Finkbeiner. Addressing endocrine-related human health effects in life cycle impact assessment (LCIA). Society of Environmental Toxicology and Chemistry (SETAC) Europe, Dublin, N/A, IRELAND, May 03 - 07, 2020.
Impact/Purpose:
Abstract submitted to the Society of Environmental Toxicology and Chemistry (SETAC) Europe meeting May 2020. This abstract describes a method to develop exposure factors for certain classes of chemicals for use in lifecycle assessments
Description:
1. Introduction Over the last decade, the release of endocrine-disrupting chemicals (EDCs) into the environment has become a matter of unprecedented public and scientific debate. EDCs are capable of interfering with and altering functions of the endocrine (hormone) system of living organisms, leading to multiple adverse health effects in humans such as reproductive malfunctions and hormone-sensitive cancers. Despite growing concerns over the now ubiquitous presence of EDCs in the environment, endocrine-related human health effects are not yet considered in human toxicity characterization within life cycle impact assessment (LCIA). To address this gap, the aim of the present study is to propose a new methodological framework to integrate endocrine-related health effects into human toxicity characterization. The proposed framework is designed to be consistent with existing LCIA toxicity characterization approaches for quantifying human health impacts related to cancer and non-cancer effects. 2. Materials and methods The proposed methodological framework mirrors the general cause-effect chain for human toxicity impacts in LCIA as implemented in the scientific consensus model USEtox. The USEtox model combines human intake fractions with effect factors into substance-specific characterization factors, expressing the human toxicity potential of chemical emissions. Intake fractions combine environmental fate and human exposure, expressed as population intake per unit emission into a given environmental compartment, while effect factors relate the population intake to the respective incidence risk for a given effect type (e.g. cancer). In the present study, we propose two approaches for deriving human toxicological effect factors for EDCs. In approach 1, we derive effect factors from in vivo endocrine-relevant effect data (i.e. data on endpoints indicative of endocrine mechanisms) for humans and animals. In approach 2, we derive effect factors from in vitro endocrine-relevant effect data. We use data from the European Commission’s “Endocrine Disruptors Database” in approach 1 and high-throughput screening (HTS) data from the U.S. ToxCast program on estrogen receptor (ER) and androgen receptor (AR) pathway activity in approach 2. We initially extrapolate towards a common point of departure for endocrine effects – a human equivalent lifetime dose – used to determine effect factors and expressing a 50% lifetime endocrine-related disease probability in the exposed human population (kgintake/lifetime). In order to later integrate our endocrine-related effect factors with intake fractions available in USEtox, we introduce an in vitro-to-in vivo extrapolation (IVIVE) step that allows the calculation of dosimetry-adjusted oral equivalent doses from in vitro HTS data. In a final step, in vivo and in vitro-derived effect factors are combined with intake fractions from USEtox to calculate characterization factors for EDCs related to inhalation and ingestion exposure. 3. Conclusions We propose a methodological framework for consistently integrating endocrine-related health effects into human toxicity characterization within LCIA. We derive endocrine-related effect and characterization factors for EDCs, using both in vivo and in vitro effect data. Our proposed approaches are consistent with existing LCIA toxicity characterization methods and can be integrated into available LCIA models. Despite relevant uncertainties, related mainly to uncertainty and variability in the underlying endocrine-related effect data and extrapolations, our framework constitutes a valuable starting point for increasing the granularity of addressed health endpoints in current LCIA toxicity impact characterization. This abstract does not necessarily represent US EPA policy.