Can nivalenol and aflatoxin M1 reflect dietary exposure?

Nivalenol and aflatoxin M1 are both food-related mycotoxin markers, but they differ substantially in their source pathways and the maturity of evidence for biomonitoring interpretation.

Dietary exposure and biomarkers

• Urinary aflatoxin M1 (AFM1) is a well-supported marker of recent dietary aflatoxin B1 (AFB1) exposure. After AFB1 ingestion, hepatic metabolism produces AFM1; about 1.5–2% is excreted in urine. Validated LC–MS methods support measurement, although the small, variable urinary fraction and timing of collection prevent a single result from precisely estimating usual individual intake.
• Urinary nivalenol is a plausible qualitative indicator of dietary exposure, but is less fully characterized. In one Cameroon biomonitoring study, nivalenol was detected in 53% of samples. However, human elimination kinetics, the relevant exposure window, and a validated urine-concentration–to–dietary-intake conversion remain insufficiently established. Results may also differ depending on whether free or deconjugated (“total”) nivalenol is measured.

Food sources and mechanisms

• Nivalenol is strongly linked to contaminated cereal commodities. EFSA reviewed 13,164 occurrence results from 18 European countries, identifying nivalenol in grains and grain products, particularly oats, maize, barley, wheat, and related foods. Bread, pasta, bakery products, milling products, and breakfast cereals can therefore contribute to exposure. EFSA-estimated chronic exposure was below its tolerable daily intake of 1.2 µg/kg body weight/day in assessed populations.
• AFM1 in dairy reflects the animal-feed pathway: dairy animals ingest AFB1-contaminated feed, metabolize AFB1 to AFM1, and secrete AFM1 into milk. AFM1 has been documented in raw, pasteurized, and UHT milk, yogurt, and cheese; a 2025 umbrella review estimated detection in 66.2% of surveyed dairy samples, with substantial heterogeneity.

Bottom line

• AFM1 is an established marker of recent AFB1 exposure and a recognized milk/dairy contaminant; nivalenol is firmly associated with contaminated grains but remains an emerging, qualitative urinary exposure marker rather than a validated quantitative intake measure.