The route of degradation of 2,4-DB under aerobic laboratory conditions was investigated in two studies. The aerobic half-life calculated from the data was between 1 and 23 days. The volatile radioactivity was confirmed (>90%) to be carbon dioxide, which was one of the major degradation products of the aerobic metabolism. 2,4-DB thus, mineralised to a large extent. Degradation of 2,4-DB resulted in the formation of one major degradation product, 2,4-D, with a half-life of 1 to 38 days. The degradation products 2,4-DCP, 2,4-DB-OH and the unknown component (2,4-DB methyl ester) were only observed as minor metabolites. Therefore, it can be assumed that these products are of transient nature. The proposed pathway indicates that 2,4-DCP is only formed from 2,4-D. According to the RMS, there are indications that the hypothesis of 2,4-DCP being formed directly out of 2,4-DB may not be excluded without adequate justification.