Sir

The possibility that the children of individuals affected by the teratogen thalidomide may inherit similar abnormalities has again been raised. Huang and McBride1 have presented data that purport to show that thalidomide is capable of binding covalently to the DNA of rat embryos whose mothers were treated with the chemical on day 12 of pregnancy. These data were interpreted by the authors to support an earlier claim by McBride that thalidomide represents the first known human germ-cell mutagen2.

The latest paper was preceded by an editorial3 in which it was stated that “the paper contains so many inadequacies that it is not possible to draw any conclusions⃛. The data do not shed any light on the possible mode of the teratogenic action of thalidomide.” It appears that the editors of the journal decided to publish the paper with the aim of formally discrediting the work. In the circumstances, this unprecedented stratagem seems to be justified. Nonetheless, the editorial warnings have been largely ignored and the sparse experimental data presented have been transmuted by a number of newspapers and magazines to the alleged demonstration of a specific interaction between thalidomide and the DNA of rat sperm and ova.

Given this accelerating distortion of science, and the human distress it may cause, it is appropriate to note that the definitive study of the mutagenic potential of thalidomide mentioned earlier4 is now in press with Mutation Research5. Leading investigators from five centres in the United Kingdom, the United States and the Netherlands have conducted exhaustive tests on this chemical using a wide range of in vitro and in vivo mutagenicity assays. The range of tests extends from cytogenetic studies conducted using human lymphocytes and fetal rabbit S9 mix to the first bone marrow micronucleus assay conducted in the rabbit. Uniformly negative results were obtained in each assay, and it is concluded that thalidomide is not a mutagen.

Any further discussion of the transmission to the next generation of birth deformities induced by thalidomide will therefore represent uninformed speculation. Prepublication copies of the Mutation Research paper5 are available for study by competent authorities.