Appropriateness to set a group health-based guidance value for fumonisins and their modified forms

The EFSA Panel on Contaminants in the Food Chain (CONTAM) established a tolerable daily intake (TDI) for fumonisin B₁ (FB ₁) of 1.0 μg/kg body weight (bw) per day based on increased incidence of megalocytic hepatocytes found in a chronic study with mice. The CONTAM Panel considered the limited data available on toxicity and mode of action and structural similarities of FB _2-6 and found it appropriate to include FB ₂, FB ₃ and FB ₄ in a group TDI with FB ₁. Modified forms of FBs are phase I and phase II metabolites formed in fungi, infested plants or farm animals. Modified forms also arise from food or feed processing, and include covalent adducts with matrix constituents. Non-covalently bound forms are not considered as modified forms. Modified forms of FBs identified are hydrolysed FB _1-4 (HFB _1-4), partially hydrolysed FB _1-2 (pHFB _1-2), N-(carboxymethyl)-FB _1-3 (NCM-FB _1-3), N-(1-deoxy-d-fructos-1-yl)-FB ₁ (NDF-FB ₁), O-fatty acyl FB ₁, N-fatty acyl FB ₁ and N-palmitoyl-HFB ₁. HFB ₁, pHFB ₁, NCM-FB ₁ and NDF-FB ₁ show a similar toxicological profile but are less potent than FB ₁. Although in vitro data shows that N-fatty acyl FBs are more toxic in vitro than FB ₁, no in vivo data were available for N-fatty acyl FBs and O-fatty acyl FBs. The CONTAM Panel concluded that it was not appropriate to include modified FBs in the group TDI for FB _1-4. The uncertainty associated with the present assessment is high, but could be reduced provided more data are made available on occurrence, toxicokinetics and toxicity of FB _2-6 and modified forms of FB _1-4.