General recommendations for soil ecotoxicological tests suitable for the environmental risk assessment of genetically modified plants

Abstract

Before a genetically modified plant (GMP) can be placed on the market in the European Union (EU), an environmental risk assessment has to be conducted according to EU-Directive 2001/18/EC or Regulation (EC) No. 1829/2003 of the European Parliament and of the Council. However, no harmonized concept for ecotoxicological testing is available today that considers the characteristics of GMPs as a whole. In fact, to date, mainly ecotoxicological tests originally developed and standardized for pesticides are used for this purpose. Frequently in these tests, not the whole GMP is tested but only specific transgene products (mainly toxins). In this contribution, ecotoxicological methods developed for the testing of pesticides are evaluated for whether they are suitable for risk assessment of GMPs as well. In total, 105 test methods covering a wide range of terrestrial invertebrates, microbes, and plants (laboratory, semifield, and field levels) were assessed. Only 7 of them had already been used with GMPs, and in about 20 studies the existing tests methods were modified, mostly in a way such that nonstandard species were used. In the laboratory, few earthworm and nontarget arthropod (NTA) species as well as collembolans and isopods were tested, and, in the field, only the litter-bag test was used. Clearly, more species than these few standard organisms currently in use have to be selected for testing purposes. A more detailed analysis of GMP tests with soil invertebrates published in the literature revealed that some of the relevant GMP exposure routes, such as via bulk soil, soil porewater, and litter from GMPs, are well covered. However, studies addressing either consumption of GMPs themselves or secondary exposure after GMPs have been taken up by invertebrates that feed on living or dead GMPs are underrepresented.

A framework for a European network for a systematic environmental impact assessment of genetically modified organisms (GMO)

“…They must represent not only arable areas, but neighbouring receiving environments including wild habitats, where the GM crops may have a potential impact or could occur. There should be a representation of at least a) the main environmental compartments (terrestrial below-and aboveground, aquatic); b) functional groups such as predators, herbivores, saprophages, and symbionts; and c) different physiological, taxonomical groups, for instance, mainly arthropods but also oligochaetes, microbes and/or fungi (Hilbeck et al 2008a;Römbke et al 2009). …”

“…Depending on the selected indicator species, these methods may require modifications or new methods must be developed. Sub-lethal endpoints, such as reproduction, should be included as criteria since they can also give indications of possible long-term effects and are more sensitive than acute (lethal) harm (Römbke et al 2009). The methods identified have to be examined in practice, preferably in inter-laboratory comparison tests, and developed into a comprehensive testing protocol.…”

“…Lab tests should be performed with the GM plant material as well as with mixtures of GM plant and conventional counterpart material, and compared to a non-GM conventional counterpart. Test data-sets must be statistically evaluated to control the test method performance under routine conditions and to help focus subsequent field testing (Römbke et al 2009). Field tests are also essential in higher tier evaluation, and must be performed, even if the proposed mode of action is well understood and laboratory tests indicate no observed effect on a given species (Romeis et al 2011).…”

Systemic risks of genetically modified crops: the need for new approaches to risk assessment

“…5 The five steps of current risk analysis procedures (hazard identification, exposure assessment, consequences assessment, risk characterization, mitigation options) were accepted as valid for GMOs, but methodologies and interpretations should be adapted to meet the specific features of living organisms and their interactions with the receiving environment [36][37][38][39]. Although Directive 2001/18/EC establishes a new framework for ERA prescribing the testing of the GMO as such (not only of the new genes and proteins) or the consideration of the receiving environment (not only some field trial locations as basis for an EU-wide approval), a review of the soil ecotoxicological tests presented in GMO dossiers concluded that they do not reflect the new legal requirements [40]. These authors, in line with Andow and Hilbeck and Snow et al, emphasise that it is crucial not to rely on standard test species only but to choose test species representative of the agro-ecological environments in which the GM plants will be grown [41,42].…”

Impact of barley (Hordeum vulgare L.) transgenic line H228.2A on substrate and rhizosphere microorganisms and the possibility of horizontal gene transfer

“…In this context, numerous investigations have been carried out to assess the impact of current agricultural practices involving extensive monoculture, reduced crop rotation, use of fertilizers, herbicides and pesticides (Giller et al, 1997), and, currently, also the increasing use of genetically modified plants (GMP) (Bruinsma et al, 2003). Potential impact of GMP on soil microorganisms is often linked to specific properties of the transgenic trait, e.g., herbicide tolerant crops will be used together with a specific herbicide, insect resistant crops will possess different variant of Bacillus thuringensis (Bt) toxins (Römbke et al, 2010), while some of GMP also possess antibiotic resistance marker genes (Demanèche et al, 2008). A number of investigations have been carried out in order to determine the impact of GMP on soil microorganisms.…”