Supposed carcinogenity of emissions from biofuels

In this paper some technical background is given about the discussion about the supposed carcinogenity of the tailpipe emissions from engines that are fed with biofuels. In this case mainly vegetable oil based fuels, like PPO (pure plant oil) and biodiesel (fatty acid methyl ester) are meant. The experiments done in Sweden and Germany are discussed and some suggestions for further research are done.