Cis-dibromoethene molecule. Computer-generated molecular model of cis-dibromoethene (C2H2Br2). The 'cis' form of dibromoethene has both bromine atoms (red) on the same side of the carbon atoms (black), which are connected with a non-rotating double bond. Hydrogen atoms are white. Trans- dibromoethene (not seen) has the bromine atoms on opposite sides of the carbon atoms. Dibromoethene has been used to fumigate fruit and vegetable produce to kill pests. However, there is concern about its effect on human health because it is carcinogenic (cancer-causing). See image A700/212 for trans-dibromoethene.