A review of current and projected nanotechnology-derived food ingredients, food additives and food contact materials is presented in relation to potential implications for consumer safety and regulatory controls. Nanotechnology applications are expected to bring a range of benefits to the food sector, including new tastes, textures and sensations, less use of fat, enhanced absorption of nutrients, improved packaging, traceability and security of food products. The review has shown that nanotechnology-derived food and health food products are set to grow worldwide and, moreover, a variety of food ingredients, additives, carriers for nutrients/supplements and food contact materials is already available in some countries. The current level of applications in the European food sector is at an elementary stage; however, it is widely expected that more and more products will be available in the EU over the coming years. The toxicological nature of hazard, likelihood of exposure and risk to consumers from nanotechnology-derived food/food packaging are largely unknown and this review highlights major gaps in knowledge that require further research. A number of uncertainties and gaps in relevant regulatory frameworks have also been identified and ways of addressing them proposed.
Summary1. Non-lethal methods of controlling wildlife foraging damage may offer conservation, ethical, legal and efficacy advantages over lethal control. Chemical repellents present a potential non-lethal approach, but have not been adequately researched in natural environments. Many previous studies have been poorly designed and a lack of data on individual behavioural responses has limited the practical development of repellents. We aimed to identify effective repellents for resolving feeding conflict with wild mammals, using European badgers Meles meles as models. 2. We tested the relative efficacy of capsaicin, cinnamamide and ziram, in a multichoice paradigm, using remote video-surveillance to obtain detailed behavioural observations of known free-ranging individuals. Treatment nights were alternated with control nights over 56 nights. 3. Badgers discriminated precisely between the four treatments, demonstrating a clear preference for untreated baits, followed by cinnamamide and capsaicin (in no particular order) and then ziram. 4. All untreated baits, and baits treated with capsaicin or cinnamamide, were eaten throughout the trial. 5. Ziram baits were fully consumed on treatment nights 1 and 2. Ziram consumption then declined to zero between treatment nights 3 and 9, this coinciding with a sharp rise in bait patch rejection. This 'learning curve' peaked at treatment night 7. We conclude that badgers developed conditioned taste aversion towards ziram-treated baits at this point. Ziram bait consumption was practically zero over the last 20 treatment nights (40 trial nights) and individuals avoided ziram baits, without sampling, for the last 12-22 treatment nights (24-44 trial nights). Observed changes in badger behaviour suggested that avoidance at a distance was facilitated by odour cues. 6. Synthesis and applications. This study provides proof of the concept that ziram has clear potential for reducing badger feeding damage through conditioned taste aversion to an odour. Our detailed observations allowed us to elucidate the behavioural mechanism involved, crucial for directing future development of this approach, thus demonstrating the importance of studying individual responses in wildlife management research. Second-order conditioning, such as this, might be applicable to managing other wild mammals. The next step will be to develop a strategy for use in wildlife damage situations.
Systemic application of sodium silicate can significantly enhance the levels of leaf silica in winter wheat (Triticum aestivum L. cv. Mercia), suggesting that this material could reduce the palatability of plants to vertebrate herbivores (e.g. rabbits, Oryctolagus cuniculus L.). A bioassay was developed using hydroponically grown wheat plants. Plants treated with sodium silicate were significantly more resistant to grazing by wild rabbits than untreated plants, with severe, potentially lethal feeding damage being reduced by over 50%. Further studies were carried out to develop more practical techniques for boosting silica levels in plants using silicon-rich 'fertilisers' including calcium silicate and calcium silicate slag (CSS). Silica levels were elevated in the plant 1.9-2.8 times over the control through the application of various silicon materials, in line with those of the hydroponic treatment. Encouragingly, levels of silica were elevated even in young wheat plants, which are most vulnerable to rabbit damage, and in a range of wheat varieties. The use of CSS is particularly promising because of its lower cost in comparison with calcium silicate, and it has a proven track record in slag fertilisation of rice and sugar cane crops. At the optimum CSS application rate of 3 g silicon L(-1) soil, wheat silica levels were approximately doubled, with no detrimental impacts on long-term growth or yield.
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