Introduction to Human Nutrition

Food Safety 345

results from intoxication rather than infection. In the
case of fungi, several species are involved in the pro-
duction of toxic substances during growth on food-
stuffs. These toxins are known as mycotoxins. Algal
toxins are usually associated with seafood, most
notably molluscan shellfi sh.

Bacterial toxins

Three bacteria are most commonly associated
with preformed toxin production: Clostridium botu-
linum, Staphylococcus aureus and Bacillus cereus (see
Table 14.1).

Fungal toxins (mycotoxins)

Mycotoxins are secondary metabolites of molds that
can induce acute and chronic symptoms, such as
carcinogenic, mutagenic, and estrogenic effects in
humans and animals. Acute toxicity due to mycotox-
ins is associated with liver and kidney damage.
Chronic toxicity resulting from the exposure of low
levels of mycotoxins in the human diet is a major food
safety concern. In nonindustrialized countries myco-
toxins have been reported to be responsible for
increased morbidity and mortality in children owing

to suppression of their immune systems and greater

susceptibility to disease.

The principal fungi that are associated with myco-

toxin production are the genera Aspergillus, Penicil-

lium, and Fusarium. Aspergillus and Penicillium are

sometimes referred to as storage fungi as they can grow

at low water activity levels and are associated with the

post-harvest spoilage of stored food commodities such

as cereals, nuts, and spices. Fusarium species are plant

pathogens and can infect plants in the fi eld and produce

mycotoxins preharvest. Table 14.8 provides an over-

view of the most important mycotoxins.

Seafood toxins

Fish and fi shery products are nutritious foods and are

desirable components of a healthy diet. Food-borne

illnesses resulting from the consumption of seafood

are associated with both fi nfi sh and molluscan shell-

fi sh. The major risk of acute illness is associated with

the consumption of raw shellfi sh, particularly bivalve

molluscs. The consumption of these toxic shellfi sh by

humans can cause illness, with symptoms ranging

from mild diarrhea and vomiting to memory loss,

paralysis, and death. Toxins associated with phyto-

Table 14.8 Mycotoxins in the food supply

Mycotoxin Producing fungi Main foods affected Toxicity

Afl atoxins Aspergillus fl avus and A. parasiticus Nuts, cereals, dried fruit, herbs
and spices, milk (afl atoxin M1)

Carcinogenic, hepatotoxic

Ochratoxin A Aspergillus ochraceus, Penicillium
verrucosum, and other Aspergillus
and Penicillium spp.

Coffee, dried fruit, cereals, beans,

pulses, wine, beer, grape juice;

kidney, liver and blood from

animals fed with contaminated

feed

Nephrotoxic, immunotoxic

Patulin Aspergillus clavatus, also several
species of Penicillium, Aspergillus,
and Byssochlamys

Fruits and grains, predominantly

apples and apple products

Cytotoxic

Trichothecenes
(nivalenol,
deoxynivalenol,
T2-toxin, etc.)

Fusarium spp. Wheat, maize, barley, oats, rye,

malt, beer, bread

Dermotoxic, enterotoxic, hemotoxic,

immunotoxic

Fumonisins Fusarium spp. Cereals, mainly corn Carcinogenic, cytotoxic, hepatotoxic
Sterigmatocystin Aspergillus versicolor, A. nidulans,
and other Aspergillus spp.

Cereals, green coffee, herbs and

spices, raw meat products

Hepatotoxic and nephrotoxic,
carcinogenic
Citrinin Penicillium spp., Aspergillus spp. Cereals Nephrotoxic
Zearalenone Fusarium graminearum Maize, barley, oats, wheat, rice,
sorghum, bread

Estrogenic effects, feed refusal,
vomiting
Moniliformin Fusarium spp. Cereals, maize Nephrotoxic, causes necrosis of the
heart muscle