Developmental toxicity tests evaluate the extent to which exposures to chemicals can interfere with normal development and cause adverse effects in the offspring. This can include effects resulting from parental exposures before and during pregnancy, as well as effects resulting from exposures during infancy or childhood.
Testing for a chemical’s potential to cause developmental toxicity is required by multiple regulatory agencies and uses large numbers of animals. NICEATM supports efforts to develop, validate, and implement alternative approaches to identify potential developmental toxicants that replace, reduce, or refine animal use.
In a May 2018 Federal Register notice, NICEATM requested information on approaches and/or technologies currently used for identifying potential developmental toxicants. This information will be used to assess the state of the science and determine technical needs for non-animal test methods to evaluate the potential of chemicals to induce adverse effects in offspring.
NICEATM published a request for information in November 2016 focused on using zebrafish embryos for chemical screening assays. These assays may be useful for identifying potential developmental toxicants.
The small size and rapid development of the zebrafish make it a useful vertebrate model for assessing potential effects of chemicals on development in a mid- to high-throughput manner. However, deficits in several key areas hinder the broader adoption of the zebrafish model for toxicological screening. NICEATM supports the NTP’s Systematic Evaluation of the Application of Zebrafish in Toxicology (SEAZIT) program, which was established to address these deficits and evaluate the feasibility of the broader adoption of zebrafish for toxicological screening.
The frog embryo teratogenesis assay - Xenopus (FETAX) - uses early-stage embryos of the South African clawed frog (Xenopus laevis) to measure the potential of chemicals to cause mortality, malformation, and growth inhibition. FETAX has been proposed as a screening assay to identify potential human developmental toxicants.
In 2000, an ICCVAM-sponsored expert panel evaluated FETAX and concluded that the assay was not sufficiently validated or optimized for regulatory applications. The panel recommended that the assay be further standardized to improve variability and that the number of endpoints assessed be increased.