HT-2 and T-2 in Oats - What we know and what we need to know Simon Edwards and Samuel Imathiu Harper Adams University College Shropshire, UK sedwards@harper-adams.ac.uk Hans Pettersson Swedish University of Agricultural Sciences Uppsala, Sweden Veli Hietaniemi MTT Laboratories Jokioinen, Finland Pers-Erik Clasen National Veterinary Institute Oslo, Norway Bruno Barrier-Guillot ARVALIS - Institut du végétal Boigneville, France
SE3 Presentation Toxicity Distribution in Europe Distribution in wheat, barley and oats Impact of agronomy on HT2 and T2 in oats Impact of processing on HT2 and T2 on oats What we need to know...
Slide 2 SE3 check what Keith is doing re: processing S Edwards; 12/11/2008
SE4 Toxicity HT2 and T2 toxins are closely related Type A trichothecenes Two of the most potent trichothecenes Have equivalent toxicity Compared to deoxynivalenol are 20-fold greater in mice and usually more than 100-fold greater to cell lines in vitro.
Slide 3 SE4 check what Keith is doing re: processing S Edwards; 12/11/2008
SE9 Toxicity The combined (HT2+T2) ttdi is 0.06 µg kg -1 bw (TDI for DON = 1 µg kg -1 bw) based on limited data (500-fold safety factor) SCOOP Task 3.2.10 estimated ttdi exceeded in many cases However Low incidence and high LoD resulted in high proportion of estimated exposure based on content of samples with no detectable HT2 or T2
Slide 4 SE9 check what Keith is doing re: processing S Edwards; 12/11/2008
Distribution in Europe Surveys conducted in Nordic countries in early 1990s More recent survey conducted in Nordic countries, UK and France Indication that increasing levels in oats Indication that some countries have some incidence on barley and maize, limited incidence in wheat
Increasing HT2 + T2 concentration in Northern European Oats
Different mycotoxin profile cereals (2007) % > 50 ppb HT2+T2 Wheat Barley Oats UK 0 2 77 Norway 0 7 94 Finland 3 16 53 Sweden 0-91 France 3 29 (Spring) -
UK Conventional Oats highest reported HT2 and T2 HT2+T2 concentration (ppb) Year Sample No. %>10ppb Mean Median 90th% 95th% Max 2002 62 97 429 160 924 1710 4844 2003 59 98 976 292 1804 2492 9990 2004 114 95 552 232 1336 2232 6997 2005 105 98 824 527 2136 2572 3188 2006 100 97 795 404 1772 3190 6261 2007 103 88 438 169 808 1875 8399 2008 90 79 120 47 351 531 1190 Conventional samples higher than organic Some variation between years but high concentration in all years
Distribution of HT2 and T2 in UK oats (2002-2005)
SE7 Correlations between Type A trichothecenes UK oats 2002-2005 Good correlations between HT2 and T2, T2 triol and neosolaniol
Slide 10 SE7 check what Keith is doing re: processing S Edwards; 12/11/2008
SE8 Correlations between Type A and Type B trichothecenes UK oats 2002-2005 No correlation between HT2 and deoxynivalenol or nivalenol Evidence of mutual exclusion Same pattern seen in UK wheat and barley
Slide 11 SE8 check what Keith is doing re: processing S Edwards; 12/11/2008
Statistical analysis To determine the effects of agronomic factors on the fusarium mycotoxin contamination of cereals For HT2 and T2 in UK oats: Multicolinearity within model Not suitable to predict risk
Multicolinearity within model Model split into two main groups: Conventional oats Most follow wheat or barley Most grow variety Gerald Organic oats Most follow non-cereals Most grow other varieties Model identified previous crop, variety and other differences between conventional and organic were all significant Need controlled field experiments to determine relative impact of different agronomic factors on mycotoxin content of oats
Analysis of UK oats by year and region HT2+T2 in oats DON in wheat
Organic and conventional UK oats Oats Much lower levels in organic oats Wheat No significant difference HT2+T2 in Oats DON in Wheat
Oat varietal differences to HT2+T2 content Differences maybe genetic or agronomic
Oat varietal differences to HT2+T2 content Differences between winter varieties likely to be genetic Little difference between spring varieties
Impact of Agronomy Different situations for different cereal crops DON and zearalenone in wheat seasonal and regional differences mass of information codes of practice available risk assessments available HT2 and T2 in oats little regional differences, some seasonal differences very limited information codes of practice not directly applicable no risk assessment available
Impact of Processing Majority of trichothecenes in outer hull (husk) All oats are de-hulled for human consumption Reductions of >90% consistently achieved Mycotoxins concentration very high in the pelleted byproduct used for animal feed
Fusarium infection of oats Fusarium on oats (panicle blight) not perceived as an important disease HT2+T2 detected in oats in mid-1990 s in Norway New species identified on oats which could produce HT2 and T2, named Fusarium langsethiae in 2004 Very limited information available about this species
Fusarium langsethiae Distinct colony morphology Slow growing easily outgrown by other fungi
Identification of Fusarium in UK oats Microbiological examination of oats with high HT2 and T2 found F. langsethiae, and no other HT2+T2 producing species DNA-based quantitative PCR developed to quantify F. langsethiae in oat material. Regression analysis indicates strong relationship between F. langsethiae DNA and HT2 and T2 concentration. PCR analysis has failed to detect other HT2+T2 producing species in UK oats. Species responsible for HT2 and T2 identified as Fusarium langsethiae in UK oats
Regression of HT2+T2 against F. langsethiae DNA 240 oat samples
Regression of HT2+T2 against F. langsethiae DNA 120 single seeds
Need for research funding COMMISSION REGULATION (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs Para 31 Intake estimates indicate that the presence of T-2 and HT-2 toxin can be of concern for public health. Therefore, the development of a reliable and sensitive method, collection of more occurrence data and more investigations/research in the factors involved in the presence of T-2 and HT-2 toxin in cereals and cereal products, in particular in oats and oat products, is necessary and of high priority.
What we need to know What is metabolic fate/toxicity of HT-2 and related type A trichothecenes? (Recent surveys have found T2 tetraol concentration to be higher than T2) What are consumption levels? (Need extensive surveys of cereal products with sensitive methods and/or monitoring of biomarkers) What meteorological factors dictate seasonal distribution of HT2 and T2 in cereals? Why are there differences between countries? Why are there differences between cereals hosts? How do agronomic factors impact on the HT2 and T2 content of cereals? How and when does Fusarium langsethiae infect cereals? How can we artificially inoculate oats? (need to conduct experiments) What varietal traits result in susceptibility/resistance to Fusarium langsethiae? Do fungicides control Fusarium langsethiae?
Acknowledgements Hans Pettersson Swedish University of Agricultural Sciences Uppsala, Sweden Veli Hietaniemi MTT Laboratories Jokioinen, Finland Pers-Erik Clasen National Veterinary Institute Oslo, Norway Bruno Barrier-Guillot ARVALIS - Institut du végétal Boigneville, France View expressed are my own and may not be those of my colleagues and/or funding bodies