Abstract
Although species of the genus Fusarium are widespread in their distribution, the natural occurrence of the toxins elaborated by these moulds has not, until recent years, been the subject of a major study. This is partly because sensitive methods which can readily be applied to nationwide surveillance programmes have been difficult to develop for the trichothecene mycotoxins produced by the fusaria. The trichothecenes have an epoxide function as a common feature of their chemical structure, and this thesis describes the reaction of the trichothecenes with a nucleophilic reagent (sodium diethyldithiocarbamate) and the subsequent development of a method based on this reaction. This method was then applied to the examination of food, and feeding stuffs and to studying the fate of deoxynivalenol through a food processing system. Although samples with levels of trichothecene contamination greater than 20mug/kg were also assayed by a different method of detection, levels below this could not be confirmed because of the lack of a suitable alternative method of adequate sensitivity. In common with the data generated from other surveillance programmes, it was found that the trichothocenes occurred occasionally at very high levels, especially in cereals. There were clear indications that the nature of the reaction occurring between trichothocenes and sodium diethylditniocarbamate (DDTC) was not analogous to that which was reported in work on an epoxide containing anti-cancer drug and DDTC, indicating nucleophilic substitution of the epoxides. Some 18 months later, independent research work proved that indeed nucleophilic substitution was not occurring, and that the reaction product being estimated was the result of a change in the DDTC reagent which was not mediated by mycotoxins. Apart from the results confirmed by alternative techniques therefore, the surveillance data must be viewed with strong reservations. A review of the current situation regarding analytical method development for the trichothecenes indicates that considerable efforts are being made in many areas. As yet, however, there is little published data on the incidence of trichothecenes in food, and therefore still a lack of information available on which to base assessments of whether fusarial toxins pose any risk to human health.