Author : Nap, Jan-Peter

Summary : The agronomic application of phosphinothricin-tolerant crops can be considered 'biosafe' with respect to its ecological consequences. There will be no increased weediness of crops. It seems inevitable that in the longer run, at some places some wild relatives of crops will acquire phosphinothricin tolerance by spread of the transgene, but also this is not likely to give problems beyond control. The toxicological consequences of phosphinothricin-tolerant crops are less clear. Without spraying, for example because the phosphinothricin tolerance was only used as selection marker during transformation, we conclude that genetically modified phosphinothricin-tolerant plants differs from the phosphinothricin metabolism in susceptible plants. As a result, phosphinothricin-derived metabolites may accumulate. The metabolites that actually accumulate depend on the amount of PAT activity present in the crop. In case PAT activity is sufficiently high, phosphinothricin is fully acetylated and only D-phosphinothricin and acetyl-phosphinothricin may be present in the plant material. These two metabolites themselves will not cause concern for consumption. If the PAT activity is low or the acetylation is not complete, metabolites of phosphinothricin (PPD, MHB and MPP) may accumulate. No data concerning the toxicology of these metabolites have been reported. Also, it is unknown how D-phosphinothricin and acetyl phosphinothricin behave upon food processing. With the current knowledge, the development of routine protocols to assess the levels of the various phosphinothricin metabolites in genetically modified plants and food is recommended. This will indicate the relative importance of the various metabolites and will indicate how relevant the concern is. Further data are necessary to determine the toxicological characteristics of the metabolites of phosphinothricin in genetically modified phosphinothricin-tolerant plants before it can be concluded are fully 'biosafe' for consumption.