Potential environmental impacts associated with large-scale herbicide-tolerant GM oilseed rape crops

Abstract

The Biomolecular Engineering Commission considers that the knowledge acquired in the last three years has provided significant information in reply to the points raised in its review dated 16 February 2001.The Commission has studied the potential environmental impacts associated with large-scale herbicidetolerantGMoilseed rape crops, making a distinction between direct and indirect impacts. Direct impacts stem from the intrinsic properties of herbicide-tolerant GM oilseed rape crops whereas indirect impacts result from practices associated with the farming of these crops.The Commission considers that, in the absence of the use of the herbicide in question in and outside of farmed land, there is no direct environmental risk (development of invasive crops per se) associated with the presence of a herbicide-tolerance gene in oilseed rape (or related species).Nevertheless, since the interest of these tolerant crops lies in the use of the herbicide in question, indirect effects, to varying extents, have been identified and must be taken into account: the use of the herbicide in question, applied to agricultural fields containing the herbicide-tolerant crop could lead to an increase in oilseed rape volunteer populations in crop rotations; the selective pressure exerted by non-specific herbicides (to which the crops have been rendered tolerant) may be very high in cases of continuous and uncontrolled use of these herbicides, and may result in the persistence of rare events such as the reproduction of fertile interspecies hybrids; the change to the range of herbicides used should be conveyed by more effective weed control and, like any change in farming practices, induce indirect effects on the agri-ecosystem, particularly in terms of changes to weeds and the associated animal life. Accordingly, the Biomolecular Engineering Commission recommends a global approach in terms of the large-scale farming of herbicide-tolerant crops that: accounts for the characteristics of the herbicide and its current and future use; accounts for herbicide-tolerant varieties belonging to other species, liable to be farmed in French agriculture in the short term; targets, if applicable, the selection of crop/herbicide combinations according to the constraints associated with French agriculture; coordinates the evaluations conducted on herbicide-tolerant crops and those conducted on herbicides; implements a biovigilance system and its associated resources whenever herbicide-tolerant crop farming is envisaged. Our report highlights the need for the management of any herbicide-tolerant GM oilseed rape crops. Such a management plan must account for the diverse cropping situations, including crop rotations and farming practices. Management should be based on the prior evaluation of situations encountered, the development of measures commensurate with the risks, and a validation of their efficacy through biovigilance.The Biomolecular Engineering Commission considers that the indirect environmental and agronomic impacts associated with current management practices employed for herbicide-tolerant oilseed rape crops can only be determined, in addition to the knowledge acquired, by continuing ongoing experimental studies initiated. Mathematical and computer models – by formalizing complex scenarios that incorporate the functioning of different oilseed rape populations (farmed, spontaneous, volunteer plants) under specific farming practices – enables the simulation of potential impacts and the identification of suitable management measures. Nevertheless, at the present time, the introduction of more extensive farming than that currently practised, or managed progressive introduction, would make it possible to progress in the study of impacts and develop and validate management procedures enabling the limitation of adverse impacts.In the specific case of imports, the Biomolecular Engineering Commission considers that herbicidetolerant GM oilseed rape seed imports for processing and animal feed does not represent additional risks for the environment compared to other oilseed rape varieties on the market. Due to the very low likelihood of the dispersal of tolerant oilseed rape crops from imported seed, the impact of the herbicides used on communication routes is considered to be negligible in the current context. However, in order to supplement the information available on environmental impacts and avert any changes to the current situation, the Commission recommends that a general monitoring plan be implemented in parallel to the introduction of seeds onto the market.Finally, the Biomolecular Engineering Commission considers that biovigilance systems adapted to the various risks should be in place before any farming of commercial herbicide-tolerant varieties is undertaken.The Biomolecular Engineering Commission considers its analysis to be valid for non-selective herbicidetolerant varieties of oilseed rape obtained both by transgenesis and by means of a technique other than transgenesis.