Non-animal Methods and Strategies for Developmental Toxicity

Predictive Model of Embryonic Vascular Development

Work to identify alternative methods for developmental toxicity testing has focused on understanding and predicting disruption of key mechanisms in embryonic and fetal development. Adverse outcome pathways provide a useful framework for integrating the evidence derived from in silico and in vitro systems to inform chemical hazard characterization.

An ongoing collaboration between NICEATM and EPA has built and applied an adverse outcome pathway for developmental toxicity through a mode of action linked to embryonic vascular disruption. This adverse outcome pathway was then applied to ToxCast high-throughput screening data to develop predictions of chemicals’ potential to disrupt angiogenesis (Saili et al. 2019). The predictions were evaluated for 38 compounds tested across a suite of functional assays for the angiogenic cycle, including assays in complex cell systems, virtual tissues, and small model organisms. Results increased confidence in the capacity of high-throughput screening data to predict developmental vascular toxicity.

Request for Data and Information on Technologies Used for Identifying Potential Developmental Toxicants

In May 2018, NICEATM requested available data and information on approaches and/or technologies currently used to identify potential developmental toxicants. Submitted information would help:

• Assess the state of the science for these approaches and technologies.
• Determine technical needs for approaches to assess this endpoint.

While the Federal Register notice asked that data be submitted by June 2018, NICEATM continues to accept submissions of relevant data. Respondents to this request should provide information on activities relevant to development or validation of alternatives to in vivo developmental toxicity test methods. NICEATM also requests available data from in vivo developmental studies, human or animal studies, or accidental human exposures, using the same chemicals that are used to evaluate the alternative developmental toxicity test methods.

Respondents to this request for information should include their name, affiliation (if applicable), mailing address, telephone, email, and sponsoring organization (if any) with their communications. Responses to this notice will be posted on this webpage, so no proprietary, classified, confidential, or sensitive information should be included in responses. Persons submitting responses will be identified by name and affiliation or sponsoring organization, if applicable.

The May 2018 request followed a similar request for available data and information issued in June 2016.

• Federal Register notice announcing data request – May 7, 2018
• Federal Register notice announcing data request – June 30, 2016
• Guidelines for Submission of Developmental and Reproductive Toxicity Data

Request for Data and Information on Zebrafish Embryo Screening

In November 2016, NICEATM issued a request for available data and information on zebrafish embryo screening tests and protocol design, including pharmacokinetic measurements. This information was used to:

• Assess the state of the science for these methods.
• Determine technical needs for approaches to assess developmental effects.

While the Federal Register notice asked that data be submitted by December 2016, NICEATM continues to accept submissions of relevant data. Respondents should provide information on any activities relevant to the development or validation of zebrafish embryo screening assays.

NICEATM is particularly interested in how study design may influence measures of toxicity/bioactivity and the kinetics associated with chemical uptake. For comparative purposes, NICEATM also requests any available data from in vivo developmental studies using the same chemicals. NICEATM specifically requests information on efforts to optimize zebrafish embryo screening tests and protocol design, including comparisons of:

• Zebrafish strains.
• Embryos with and without an intact chorion, the permeable membrane enclosing the zebrafish embryo.
• Static and static-renewal exposure protocols (i.e., leaving the exposure solution unchanged during the testing period vs. providing fresh exposure solution periodically during the testing period).

NICEATM is also interested in developing a better understanding of pharmacokinetics in the zebrafish embryo model and requests available data on chemical uptake.

• Federal Register notice announcing data request – November 3, 2016
• NTP Guidelines for Public Comments