Vol. 23, No. 6
Publications from the World Health Organization
Fumonisin B1 , Environmental Health
Criteria No. 219, 2000, xix + 150 pages (English, with summaries in
French and Spanish), ISBN 92-4-157219-1, CHF 36.-/ USD 32.40; In developing
countries: CHF 25.20, Order No. 1160219.
This book evaluates the risks to human and animal health posed by the
consumption of maize and maize-based products contaminated with fumonisin
B1 . This naturally occurring mycotoxin, produced
by the mold Fusarium verticillioides, is found in high concentrations
throughout the world, and is believed to be the most prevalent and toxic
of the fumonisins. Consumption is known to cause two fatal diseases
in farm animals. Possible adverse effects on human health are of particular
importance in several developing countries, where maize and maize-based
products are the staple food for large populations. A section on sources
of human exposure considers factors that influence the vulnerability
of maize to contamination during growth, storage, and processing.
Weather conditions that favor Fusarium kernel rot are noted to cause
significant accumulation of fumonisin B1 . Studies
of the effects of different processing techniques demonstrate the toxin's
stability. Dry milling results in its distribution into the bran, germ,
and flour. In experimental wet milling, fumonisin has been detected
in steep water, gluten, fiber, and germ, but not in the starch.
A review of studies on the environmental fate of fumonisin B1
concludes that fumonisins are heat-stable, light-stable, water-soluble,
poorly absorbed, poorly metabolized, and rapidly excreted by animals.
As a result, most fumonisin is recycled into the environment in a manner
that concentrates its spatial distribution. A section on environmental
levels and human exposure reviews a large number of studies measuring
levels of contamination in maize and maize-based foods for human consumption
and in animal feeds. The highest levels of contamination have been recorded
in Europe, followed by North America, Africa, Asia, and Latin America.
The most extensive section reviews toxicity data from studies in experimental
animals and in vitro test systems. Fumonisin B1 has
been shown to be hepatotoxic in all animal species tested, and nephrotoxic
in several species. The report found no evidence that consumption of
fumonisins causes adverse effects on development of reproductive functions
in farm animals or humans. Studies in some species indicate an association
between exposure and the development of renal and liver cancers. The
evaluation also drew on extensive investigations of equine leukoencephalomalacia
and porcine pulmonary edema syndrome, fatal diseases that have been
causally linked to the consumption of fumonisin-contaminated feeds.
These and other lines of evidence suggest that fumonisin B 1
exerts its toxic action by inhibiting cell growth and causing
accumulation of free sphingoid bases and alteration of lipid metabolism.
The evaluation of effects on human health draws on limited evidence
from correlation studies, in South Africa and China, and an analytical
study, from northen Italy, suggesting a link between direct fumonisin
exposure and esophageal cancer. Owing to weaknesses in all these studies,
no firm conclusions could be reached. No confirmed records of acute
fumonisin toxicity in humans were available for evaluation.
A final section draws attention to the urgent need for more knowledge
about the effects of food processing and cooking, especially in developing
countries, on levels of contamination, for epidemiological studies of
adverse health effects, and for better understanding of the mode of
toxic action in humans.