The 1-year dog toxicity study is of little relevance for pesticide registrations in Japan

Abstract

A retrospective review has been performed of Acceptable Daily Intakes (ADI) for pesticide residues in Japan where dog studies have provided the pivotal data for their derivation.  A set of 46 ADIs which are based on the results of dog toxicity studies (normally 1-year) were examined and reassessed under the assumption that the 1-year dog study had not been conducted , thus  requiring the derivation of the ADI from an alternative toxicology study. A resulting ADI up to 2 times higher was not considered to be a real difference and was found in 36 of the 46 data sets (78.3%). An ADI 2-5 times higher was found in another 6/46 data sets (13%), but is potentially  not   a toxicologically
relevant difference or requiring additional studies, while for 3/46 data sets (6.5%) there may be a real difference. Only 1/46 data sets (2.2%) showed an ADI higher than 5 times.
The incidences of 3/46 plus 1/46 should not only be assessed within the specific data set investigated, but against the total of all registrations of conventional pesticides in Japan, a number exceeding 400 active substances. Accordingly, the absence of a 1-year dog study would not influence the ADI derivation in a relevant manner for more than 98% of these pesticides.
Therefore the standard requirement to conduct a 1-year dog study in addition to the 3-month study cannot be justified.