IARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC ...

Since fumonisin B 1 is present in the spores and mycelia of F. verticillioides (Tejada-
Simon et al., 1995), occupational inhalation exposure could be a problem, but data are
lacking on airborne levels of fumonisins during the harvesting, processing and handling
of fumonisin-contaminated maize.
In a study conducted in China, urine was collected from volunteers before and after
consumption of a fumonisin B 1-contaminated diet for one month. The ratio of free sphinganine
to free sphingosine (Sa/So) was increased threefold in the urine of the men, but
was unchanged in that of the women. This increase was also apparent when the data were
pooled for men and women and grouped into those individuals who had estimated
intakes of fumonisin B 1 greater than or less than 110 μg/kg bw per day (Qiu & Liu,
2001).
This result is similar to that reported for swine, where the sphinganine/sphingosine
ratio became significantly different from controls at a fumonisin B 1 intake of 500 μg/kg
bw per day (Rotter et al., 1996).
1.6 Regulations and guidelines
FUMONISIN B 1
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has
recommended a provisional maximum tolerable daily intake (PMTDI) of 2 μg/kg bw for
fumonisins B 1, B 2 and B 3, alone or in combination (JECFA, 2001).
An official tolerance value for dry maize products (1 mg/kg fumonisin B 1 plus fumonisin
B 2) has been issued in Switzerland (Canet, 1999).
The recommended maximum levels for fumonisins in human foods and in animal
feeds in the USA that the FDA considers achievable with the use of good agricultural and
good manufacturing practices are presented in Tables 2 and 3. Human exposure to fumonisins
should not exceed levels achievable with the use of such practices (Food and Drug
Administration, 2001c).
2. Studies of cancer in humans
Studies on the relationship between Fusarium verticillioides (formerly known as
F. moniliforme) toxins (of which fumonisin B 1 and fumonisin B 2 are the major toxic
secondary metabolites) and oesophageal cancer in areas of South Africa and China were
summarized in Volume 56 of the IARC Monographs (IARC, 1993). The evidence in
humans was judged to be ‘inadequate’ at that time.
The only subsequent study that investigated the relationship between fumonisins and
cancer was carried out in the People’s Republic of China. Yoshizawa and Gao (1999)
collected 76 corn samples from the homes of oesophageal cancer patients, selected at
random in Linxian, China (a high-risk area for oesophageal cancer) as well as 55 samples
from homes of peasant families with no oesophageal cancer patient in Shangqiu (a low-
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