Overview
The European Food Safety Authority (EFSA) FEEDAP Panel evaluated a renewal application by BASF SE for the feed additive consisting of bentonite (dioctahedral montmorillonite) under EU Regulation 1831/2003. The additive is used as an anticaking agent in feed for all animal species and as a mycotoxin-reduction substance in feed for pigs, poultry, and ruminants. The Panel concluded that the additive is safe for target animal species, consumers, and the environment under the authorized conditions of use, and that the additive is not genotoxic. The key heavy metal finding is a nickel impurity of 6.0 to 6.7 mg/kg detected as a contaminant in the commercial bentonite product across five analyzed batches. Crystalline silica was present at 0.01 to 0.04%.
Key numbers
Table 1 (p. 4-5): Mineralogical and chemical composition, impurities of BASF SE bentonite
Mineralogical composition (XRD, mean and range):
- Smectite: 89.2% (88.2-90.3%), n=5 batches
- Quartz: 2.8% (2.1-3.8%)
- Feldspar: 4.0% (3.4-4.8%)
- Calcite: 3.4% (2.6-4.0%)
Specification requirements for mycotoxin-reduction use: smectite (dioctahedral montmorillonite) at least 70%; opal and feldspar below 10%; quartz and calcite below 4%; aflatoxin B1-binding capacity above 90%.
Specification requirements for anticaking use: smectite at least 50%.
Measured aflatoxin B1-binding capacity: 97.0% (96.3-97.4%), n=5 batches.
Impurities (Table 1):
- Crystalline silica: 0.01-0.04%, n=3 batches
- Nickel: 6.0-6.7 mg/kg (6,000-6,700 ppb), n=3 batches
The Panel noted that nickel was identified as an impurity requiring attention for user safety (Section 3.2.4). Nanoparticles cannot be excluded based on transmission electron microscopy.
Safety conclusions:
- Not genotoxic (bacterial reverse mutation test and in vitro mammalian micronucleus test both negative)
- Safe for target animal species and consumers under authorized conditions of use
- Bentonite is a skin sensitiser and respiratory sensitiser; exposure by any route is a risk for users
- Bentonite is mildly irritant to eyes and not irritant to skin
Methods (brief)
Dossier-based evaluation under EU Regulation 1831/2003 and Regulation 429/2008. Mineralogical analysis by X-ray diffraction (XRD). Elemental analysis by X-ray fluorescence (XRF). Aflatoxin B1-binding capacity test method. Nickel and crystalline silica quantified from product batch analysis submitted by the applicant. Genotoxicity: bacterial reverse mutation (Ames) test and in vitro mammalian micronucleus test. No new animal feeding studies conducted under this renewal.
LOD/LOQ: not reported for impurity measurements. CRM: IAEA-356 marine sediment reference material cited for earlier studies but not stated for this renewal batch analysis. Recovery: not reported.
Evidence Fitness
EF-2 (regulatory scientific opinion). This is an authoritative EFSA regulatory assessment covering commercial bentonite manufactured by BASF SE for use as a feed additive. The impurity data (nickel 6.0-6.7 mg/kg) are from product batches of a commercially produced bentonite, not from raw geological bentonite or geophagic clay. The safety context is animal feed use, not direct human consumption. The nickel impurity value is relevant as a reference point for commercial bentonite products marketed as dietary supplements to humans, as the same material type is used in both applications. The authorisation covers bentonite as a food-contact or feed ingredient; it is not a food safety limit for human dietary supplement use.
Implications
Products: The nickel impurity concentration in EU-authorized commercial bentonite (6.0-6.7 mg/kg) provides a reference range for nickel in processed bentonite products at the purer end of the commercial spectrum. Dietary supplement bentonite marketed to humans is the same mineral class. The absence of genotoxicity under EFSA’s test battery is relevant context for bentonite supplement safety discussions. The 97% aflatoxin B1-binding capacity informs why bentonite is marketed as a detox supplement.
Courses: Illustrates the regulatory pathway for clay minerals in food-chain applications and the gap between animal-feed standards and human-supplement oversight.
Related evidence
- Clay and geophagy
- Geophagy During Pregnancy in Sub-Saharan Africa: A Review of Cultural Practices and Health Implications.
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