: Fahrig, R.; Steinkamp-Zucht, A.

Abstract
In in vivo experiments using the spot test with mice, diethylhexylphthalate (DEHP) was co-recombinogenic and anti-mutagenic. In two independent experiments, DEHP was able to increase in combination with ethylnitrosourea (ENU) the frequency of animals with spots of genetic relevance from about 12 per cent (ENU alone) to about 15 per cent (ENU+DEHP). This enhancement can be exclusively attributed to an enhancement of recombination. In historical as well as in current experiments, with astonishing accuracy, about 8 per cent of all spots induced with ENU alone are black, near-white or twin spots, i.e., presumed products of reciprocal recombination. Under the influence of DEHP, about 20 per cent of all colored spots were black, near-white or twin spots. These co-recombinogenic effects are very strong, considering that the low frequency of twin spots with 0.3 per cent (historical ENU control) or 0.6 per cent (current ENU control) after ENU treatment alone has been enhanced up to a frequency of 3 per cent.