What are T-2 and HT-2 toxins?
T-2 and HT-2 are type A trichothecenes and the most acutely potent of the regulated Fusarium toxins. T-2 is rapidly metabolised to HT-2 in the body, which is why risk assessments and limits treat the two as a sum rather than separately.
Last reviewed 2026-11-11 · compiled by TripleBond Scientific Inc., Guelph, Ontario
Where they come from
T-2 toxin (CAS 21259-20-1) and its deacetylated metabolite HT-2 toxin are type A trichothecenes produced by Fusarium sporotrichioides, Fusarium langsethiae and Fusarium poae. They are favoured by cool, wet growing conditions, which is why they are more of a northern European and Canadian concern than a Mediterranean one.
T-2 is deacetylated to HT-2 quickly after ingestion. Since the two interconvert and share a mode of action, EFSA, the EU limits and most laboratory methods report the sum of T-2 and HT-2.
Commodities most affected
Oats most of all — by a wide margin, and especially oats with the husk — then barley, wheat and maize, and the derived oat flakes, bran and feeds.
What they do
Like all trichothecenes, T-2 and HT-2 inhibit protein synthesis at the ribosome, but they are considerably more potent than the type B trichothecenes such as deoxynivalenol. The critical effects identified by EFSA are immunotoxicity and haematotoxicity: reduced total leucocyte count was the endpoint used to derive the tolerable daily intake. T-2 is also a skin and mucosal irritant on direct contact.
IARC classifies T-2 toxin in Group 3, not classifiable as to its carcinogenicity to humans. The concern is immune and haematological, not cancer.
In 2017 the EFSA CONTAM Panel established a group tolerable daily intake of 0.02 µg/kg body weight per day for the sum of T-2 and HT-2, revised downward from the 0.1 µg/kg value set in 2011, together with an acute reference dose of 0.3 µg/kg body weight. JECFA had set a provisional maximum tolerable daily intake of 0.06 µg/kg body weight per day in 2001. The EFSA group tolerable daily intake is the lowest of any of the regulated Fusarium toxins, which reflects their potency.
Regulatory limits in brief
T-2 and HT-2 became binding EU maximum levels under Regulation (EU) 2024/1038, applicable since 1 July 2024; before that they were covered only by an indicative-level recommendation. Levels are set for the sum of the two, with the highest allowances for unprocessed oats with the husk, reflecting how concentrated they are in that fraction. In Canada the CFIA's RG-8 values for feed are guidelines. The full tables are on our mycotoxin limits page.
How laboratories measure them
Type A trichothecenes lack a conjugated ketone, so they have no useful UV absorbance and cannot be determined by HPLC-UV the way deoxynivalenol can. The practical options are LC-MS/MS, which is the standard approach and reports T-2 and HT-2 individually so the sum can be calculated, GC-MS after derivatisation, which predates the LC-MS/MS era and is still used, and ELISA for screening, where antibody cross-reactivity between T-2 and HT-2 must be known before a result is interpreted as a sum.
Because the regulatory levels are low and the tolerable daily intake is the lowest of the group, method sensitivity matters, and so does the quality of the calibration standards at the low end of the curve.
T-2 Toxin 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 are T-2 and HT-2 always reported together?
T-2 is rapidly deacetylated to HT-2 after ingestion, so the two interconvert and share a mode of action. EFSA, the EU maximum levels and most laboratory methods therefore work with the sum of the two.
Which cereal carries the highest T-2 and HT-2 levels?
Oats, by a wide margin, and especially oats with the husk still on. Barley, wheat and maize follow.
What is the tolerable daily intake for T-2 and HT-2?
The EFSA CONTAM Panel established a group tolerable daily intake of 0.02 micrograms per kilogram of body weight per day in 2017, based on reduced total leucocyte count, plus an acute reference dose of 0.3 micrograms per kilogram of body weight. This is the lowest tolerable daily intake among the regulated Fusarium toxins.
Are T-2 and HT-2 carcinogenic?
IARC classifies T-2 toxin in Group 3, not classifiable as to its carcinogenicity to humans. The established concerns are immunotoxicity and haematotoxicity.
How do T-2 and HT-2 compare with deoxynivalenol?
Both are trichothecenes, but T-2 and HT-2 are type A and considerably more potent than type B trichothecenes such as deoxynivalenol. That is reflected in a tolerable daily intake some fifty times lower.
Sources
- EFSA CONTAM Panel, Appropriateness to set a group health-based guidance value for T2 and HT2 toxin and its modified forms (2017)
- IARC Monographs, Agents Classified by the IARC Monographs
- Commission Regulation (EU) 2023/915 on maximum levels for certain contaminants in food
- Canadian Food Inspection Agency, RG-8 Regulatory Guidance: Contaminants in Feed