by several species of mould and may thus be contaminated by several
different mycotoxins.
8.4.4.2 DON and Other Trichothecenes. In Japan an illness known as
red-mould disease involving nausea, vomiting and diarrhoea has been
associated with the consumption of wheat, barley, oats, rye and rice
contaminated by species of Fusarium. The species most frequently
incriminated wasFusarium graminearum, although it had been misiden-
tified asF. nivale, and the trichothecene toxins isolated from them were
called nivalenol and deoxynivalenol. It is now realized thatF. nivaleitself
does not produce trichothecenes at all, indeed it may not even be a
Fusarium.
Deoxynivalenol (Figure 8.15), also known as DON and vomitoxin,
was also shown to be the vomiting factor and possible feed-refusal factor
in an outbreak of poisoning of pigs fed on moulded cereals in the United
States. Deoxynivalenol is much less acutely toxic than T-2 toxin, having
an LD 50 of 70 mg kg^1 in the mouse.
Nevertheless, it is more common than T-2 toxin especially in crops such
as winter wheat and winter barley. In 1980 there was a 30–70% reduction
in the yields of spring wheat harvested in the Atlantic provinces of
Canada due to infections withFusarium graminearumandF. culmorum,
both of which may produce DON and zearalenone. It is not clear whether
DON and other trichothecenes are as immunosuppressive as T-2 toxin
but it seems prudent to reduce exposure to a minimum. Several countries
have set legislative limits for DON and zearalenone in cereals and the
E.C. implemented regulatory limits for the European Union in 2006. For
DON they range from 200mgKg^1 in processed cereal based foods for
infants and ingredients used in the manufacture of food for infants to
1750 mgKg^1 in durum wheat and oats. For zearalenone they range from
20 mgKg^1 in processed cereal based products for infants to 100mgKg^1
in unprocessed cereals except maize. Maximum limits for maize are likely
to be implemented during 2007.
The most virulent group of trichothecenes are those with a macrocyclic
structure attached to the trichothecene nucleus such as the satratoxins,
verrucarins and roridins produced byStachybotrys atra(Figure 8.15).
This species has been implicated in a serious disease of horses, referred to
as stachybotryotoxicosis, fed on mouldy hay. It seems that species of
Fusariumdo not produce such toxins.
8.4.4.3 Zearalenone. Zearalenone (Figure 8.16) is an oestrogenic my-
cotoxin which was first shown to cause vulvovaginitis in pigs fed on
mouldy maize. Pigs are especially sensitive to this toxin and, although its
acute toxicity is very low, it is common in cereals such as maize, wheat
and barley being produced byFusarium graminearum, F. culmorumand
other species ofFusarium. The toxin was called zearalenone because of
294 Non-bacterial Agents of Foodborne Illness