Injury to and death of cabbage (Brassica oleracea) seedlings caused by vapours of di butyl phthalate emitted from certain plastics

Many items made of flexible plastic contain the plasticiser di butyl phthalate (DBP). When the plastic is in an enclosed volume, such as a glasshouse, vapours of DBP can reach toxic concentrations and kill cabbage (Brassica oleracea) seedlings. The phenomenon, which varies in severity between varieties, accounts for recent crop losses in certain glasshouses in which the flexible plastic used to cushion the glass, i.e. the glazing strip, was plasticised with DBP. Concentrations of DBP up to 2010 pg litre^-1 were recorded in such a glasshouse. The problem was cured by replacing the glazing strip with a strip plasticised with di iso-decyl phthalate (DIDP). A residual DBP concentration of 120 pg litre^-1 was traced to DBP contaminants in the DIDP strip. Other plastic items used in glasshouses such as hosepipes and flexible pots have also been examined, and the results of chemical analyses and bioassays are reported.