From: the Federal Register of Wednesday, October 8, 1986, Volume 51, No. 195, Page36162.
This study has limited usefulness for two reasons: (1) animals were not randomized and (2) over 50 percent of the male control mice died near the end of the first year of the study."
From: Guidance for the Reregistration of Pesticide Products Containing 1,3-Dichloropropene as the Active Ingredient. Section III. Agency Assessment. EPA. September, 1986.
The announcement that Telone was being placed into Special Review appeared in the Federal Register in October of 1986. In the NTP study, for two years, 1,3-dichloropropene mixed with corn oil was injected twice a day into the stomachs of rats and mice through a tube forced down their throats. At the conclusion of the exposures, the rats and mice were killed and their body tissues examined for evidence of carcinogenicity.
The Special Review was initiated in spite of the conclusion by US EPA reviewers that the study had limited usefulness for the two reasons listed above. In many disciplines, a lack of randomization would totally invalidate a research trial.