Toxicity testing and endocrine disrupting chemicals.

Area of Science:

• Environmental toxicology
• Endocrinology
• Chemical safety assessment

Background:

• Global regulatory agencies rely on standardized assays to assess chemicals for endocrine disrupting properties.
• The US Environmental Protection Agency (EPA) utilizes a two-tiered approach within its Endocrine Disruptor Screening Program (EDSP) to identify endocrine disrupting chemicals (EDCs).
• Existing assays target estrogen, androgen, and thyroid hormone receptors, as well as steroidogenesis, with additional methods developed through Tox21 and OECD validation.

Purpose of the Study:

• To provide an overview of the challenges and limitations in current approaches for identifying endocrine disrupting chemicals (EDCs).
• To highlight issues related to the definition of EDCs, the validity of existing assays, and their sensitivity.
• To discuss the implications of these problems for public health protection and to review potential improvements.

Main Methods:

• Review of existing regulatory frameworks and testing strategies for endocrine disruptors.
• Analysis of the impact of agency definitions on assay applicability and the concept of adverse effects.
• Examination of assumptions regarding the reproducibility and sensitivity of validated toxicity tests.

Main Results:

• The definition of an EDC significantly influences the selection and utility of specific testing assays.
• Concerns exist regarding the reproducibility and underlying assumptions of studies used to validate EDC identification methods.
• Many validated assays demonstrate lower sensitivity compared to alternative, unvalidated methods.

Conclusions:

• Current testing strategies, despite available assays, have limitations that hinder effective identification of EDCs.
• These limitations contribute to a gap in public health protection against known endocrine disrupting chemicals.
• There is a need to improve current guideline studies and testing approaches to enhance EDC detection and regulation.