Document Type

Letter to the Editor

Publication Date



This article has been peer reviewed. It is the authors' final version prior to publication in Reproductive Toxicology. Volume 29, Issue 2, April 2010, Pages 251-253. The published version is available at DOI: 10.1016/j.reprotox.2009.11.010. Copyright (c) Elsevier Inc.



1. WEC has many useful scientific purposes.

2. You cannot utilize WEC to label a drug or chemical as a teratogen if the exposures utilized will result in embryonic or fetal death in vivo.

3. WEC can indicate that a drug or chemical is embryotoxic.

4. If the exposure level for clinical use of a drug or environmental exposure of a chemical is known, it should be used in WEC studies along with higher exposures as well.

5. You cannot predict that a drug is a cardiac teratogen from WEC when no cardiac malformations are observed, as in this study. You can generate many hypotheses, but unfortunately the hypotheses generated by Sloot et al. will not make cardiac malformations appear in their WEC experiments.

6. If whole-animal teratology studies are negative with clinically appropriate exposures, WEC cannot provide information that will label the drug as a teratogen.