Project SeedPlus

A testing and assessment strategy for the development of the formulations and encapsulation technologies is being established in parallel to concerns with regard to environmental protection. In this way the environmental risk can be assessed in terms of ecotoxicity and degradability. To this end, new endpoints for assessing the degradability of polymers in the environment are being researched and established and will be applied to the layered materials developed in SeedPlus. The development of screening methods for the environmental behaviour and environmental impact of polymeric layered materials and other crop supporting chemicals allow a fast and cost-efficient development phase through the early identification of risks in relation to the regulatory acceptance of the developed product. Application of the screening methods in the development of other polymeric materials introduced into the environment is also possible.

The potential environmental risk of the substances used in the project is assessed at each stage of development. The methods developed for this purpose form the basis of an assessment strategy for biopolymers that does not yet exist. Based on the materials provided, a two-stage test strategy is pursued.

First, a broad test is carried out within the intrinsic screening procedure to assess the degradability and toxicity. Here, used and developed materials are analysed as individual components. The environmental behaviour (fate) of the components is evaluated by investigating biodegradation in miniaturised approaches with sewage sludge. The decisive factor in this analysis is a general statement on degradability (yes/no), with the possibility of a basic characterisation of degradation or identification of degradation products. Also, it may then be possible to give feedback to ecotoxicology, if studies on environmental impact with degradation products become relevant. The identification of degradation products in complex environmental matrices is made possible by the production and use of 14C-labelled formulations coupled with the establishment of analytical methods. Potentially this analytical methodology can subsequently be transferred to unlabelled substances and degradation products. For a robust assessment of degradability, a comparison of the results from the sewage sludge screening with the results of the degradation in soils by a soil degradation screening and a representative study according to OECD 307 for acceptance by regulatory authorities will be carried out.

The environmental impact is initially investigated, with solutions or aqueous eluates of the materials, on aquatic and terrestrial model organisms. To cover all trophic levels, miniaturised algae, daphnia and fish embryo tests are established. By combining these tests with OMICs methods, harmful mechanisms of action are also detected at the molecular level. Furthermore, miniaturised rapid tests are used to look at the effect on soil microorganisms. The respective results are compared with results of accepted approval tests according to OECD, ideally supported by typical literature values or alternatively by self-generated experimental values. Prior to the production of the finished product (encapsulated seed), components that have been identified as non-toxic and degradable are tested again for their effect on soil (micro)organisms to confirm safety.

Subsequently, the behaviour of the encapsulated seed is evaluated in the environmental simulation in small lysimeters. The investigation and evaluation of fate and effect on soil microorganisms is carried out simultaneously and using newly developed methods.