What is fumonisin B1 (FB1)?
Fumonisin B1 is the dominant mycotoxin of maize. It is structurally unlike the other regulated mycotoxins — a long-chain aminopolyol rather than a small ring system — and its toxicity works through a correspondingly different mechanism.
Last reviewed 2026-11-11 · compiled by TripleBond Scientific Inc., Guelph, Ontario
Where it comes from
Fumonisin B1 (FB1, CAS 116355-83-0) is produced by Fusarium verticillioides (formerly F. moniliforme) and Fusarium proliferatum. These fungi colonise maize so routinely that fumonisin is effectively a maize-specific contaminant: it is rare in wheat and barley, and maize and its products dominate human and animal exposure.
FB1 is the most abundant of the B-series fumonisins, which also include FB2, FB3 and FB4. Alkaline processing such as nixtamalisation hydrolyses the tricarballylic side chains to give hydrolysed fumonisins, which is one reason traditional maize processing changes the exposure picture.
Commodities most affected
Maize and maize products: grits, flour, meal, breakfast cereals, tortillas and maize-based feeds. Sorghum and asparagus are reported less commonly.
What it does
Fumonisins resemble sphinganine and sphingosine, and the key event in their mode of action is inhibition of ceramide synthase, which disrupts sphingolipid metabolism. The downstream effects are strikingly species-specific: equine leukoencephalomalacia in horses, porcine pulmonary oedema in pigs, and liver and kidney effects in rodents.
In humans, fumonisin exposure from maize has been associated epidemiologically with oesophageal cancer in high-maize-consumption regions, and with neural tube defects. IARC classifies fumonisin B1 in Group 2B, possibly carcinogenic to humans.
The EFSA CONTAM Panel established a tolerable daily intake of 1.0 µg/kg body weight per day for FB1 in 2018, based on increased incidence of megalocytic hepatocytes in a chronic mouse study, and included FB2, FB3 and FB4 in a group tolerable daily intake with it. JECFA set a group provisional maximum tolerable daily intake of 2 µg/kg body weight per day, retained at its later evaluations.
Regulatory limits in brief
EU maximum levels under Regulation (EU) 2023/915 are set for the sum of FB1 and FB2, with the strictest levels for maize-based foods for infants and young children. The United States works from FDA guidance levels for total fumonisins in maize products. The full tables are on our mycotoxin limits page.
How laboratories measure it
Fumonisins have neither useful UV absorbance nor native fluorescence, which historically made them awkward: HPLC with fluorescence detection requires pre-column derivatisation, typically with o-phthaldialdehyde. LC-MS/MS avoids the derivatisation step entirely and is now the dominant approach, reporting FB1 and FB2 together as the regulations require. ELISA is used for maize intake screening.
Fumonisin standards are supplied as the free base or as solutions, and the certified concentration matters as much as purity because of how the calibration is built. For kit manufacturing and proficiency material, the quantity available from a single consistent batch often becomes the limiting factor.
Fumonisin B1 (FB1) reference standard
Produced in our own Canadian laboratory, from analytical quantities through to gram and kilogram scale. Catalogue pricing is published for analytical sizes.
See the standard →Common questions
Why is fumonisin mostly found in maize?
Because the fungi that produce it, Fusarium verticillioides and Fusarium proliferatum, colonise maize routinely and rarely contaminate wheat or barley to the same extent. Maize and maize products dominate exposure.
How does fumonisin B1 cause toxicity?
It resembles sphinganine and sphingosine, and the key event is inhibition of ceramide synthase, which disrupts sphingolipid metabolism. The resulting effects are highly species-specific.
Is fumonisin B1 carcinogenic?
IARC classifies fumonisin B1 in Group 2B, possibly carcinogenic to humans. Exposure has been associated epidemiologically with oesophageal cancer in regions of high maize consumption.
What is the tolerable daily intake for fumonisins?
The EFSA CONTAM Panel established a tolerable daily intake of 1.0 micrograms per kilogram of body weight per day for fumonisin B1 in 2018, and included FB2, FB3 and FB4 in a group value with it. JECFA set a group provisional maximum tolerable daily intake of 2 micrograms per kilogram of body weight per day.
Which animals are most affected by fumonisins?
Horses and pigs are the classic cases: equine leukoencephalomalacia in horses and porcine pulmonary oedema in pigs. Rodents show liver and kidney effects.
Sources
- EFSA CONTAM Panel, Appropriateness to set a group health-based guidance value for fumonisins and their modified forms (2018)
- IARC Monographs, Agents Classified by the IARC Monographs
- Commission Regulation (EU) 2023/915 on maximum levels for certain contaminants in food
- US FDA, Guidance for Industry: Action Levels for Poisonous or Deleterious Substances