Natural Environments - Field Trials

Exposure in natural environments provides the best true measure of the environmental fate of a polymer, because these tests include a diversity of organisms and achieve a desirable natural closeness of fit between the substrate, microbial agent and the environment. However, the results of that particular exposure are only relevant to the specific environment studied, which is likely to differ substantially from many other environments. An additional problem is the timescale for this method, since the degradation process, depending on the environment, may be very slow (months 

Buchanan in Degradation Rate of Bioresorbable Materials - Prediction and Evaluation, Woodhead Publishing Ltd, Cambridge, UK, 2008. 

Albertsson and S. Karlsson in Degradable Materials - Perspectives, Issues and Opportunities, Eds., S.A. Barenberg, J.L. Brash, R. Narayan and A.E. Redpath, CRC Press, Boston, MA, USA, 1990. 

Albertsson and B. Ranby, Journal of Applied Polymer Science Applied Polymer Symposium, 1979, 35, 423. 

Nevertheless, field trials in natural environments are still used to extrapolate results acquired in laboratory tests to biodegradation behaviour under realistic outdoor conditions [119, 131]. Recent German regulations for the assessment of compostability of plastics even impose exposure of the product to a full scale industrial composting process to ensure that total disintegration will occur in real-life waste-processing [132]. 

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The principal benefits of the habituation-dishabituation test arise from the speed of testing and the minimal need for equipment. Each animal may complete a nine trial session in less then 30 minutes. An additional advantage comes with the sequential presentation of the stimuli as this methodology avoids the problems associated with the mixing of vapours from different odour stimuli if the odours are presented simultaneously. The test is particularly well suited for field work as the stimuli may be presented on a substrate that the subject normally investigates, thus elicting a more natural response than one might encounter in a lab environment. 

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