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Can anti-mould probiotics be biocides? The European Court of Justice seems to think so



On 19 December 2019, the Court of Justice of the European Union (CJEU) ruled in Case C-592/18 Darie that products containing probiotics that act preventively against a harmful organism can be classified as biocides.

It also confirmed its well-known Söll judgment (Case C-420/10) that products acting in an indirect manner can be biocides.


Article 2(1)(a) of Directive 98/8/EC (BPD) set out three cumulative criteria for the definition of a 'biocidal product':

  • the presence of an active substance;
  • the product's intention to have a biocidal effect (disinfect, preserve, etc); and
  • a chemical or biological mode of action.

The CJEU in Söll expanded the second element of this definition to include products acting by indirect means on the target harmful organisms provided that this action "forms an integral part of a causal chain" and aims to "produce an inhibiting effect" on those organisms.

Regulation (EU) No 528/2012 (BPR), implemented shortly after Söll, further expanded the criteria of the definition with respect to the third element by extending the mode of action from chemical or biological to encompass also "any means other than merely physical or mechanical action".


The product at the centre of the present Darie case contained a probiotic that was applied to a wiped surface to inhibit the breeding ground for mould. The Dutch authorities considered the product a biocide whereas, Darie BV, a commercial company, disagreed.

The CJEU was asked three questions concerning the scope of the concept of 'biocidal product' as defined in Article 3(1)(a) of the BPR.

Firstly, it was asked whether the definition of ‘biocidal product’ within the meaning of that Article includes products with a probiotic effect, which act on the potential habitat of the target harmful organism rather than on the organism itself.

Recalling the broader definition of mode of action introduced by the BPR, the CJEU confirmed that the probiotic effect of a product does not prevent it from being considered a biocide under the BPR provided that this effect does not result merely from physical or mechanical action, and that the first two criteria in the biocidal product definition are also met.

The CJEU also confirmed that the decision in Söll to include indirect effects of an active substance within the concept of a biocidal product, pursuant to the BPD, also applied to biocidal products under the BPR.

Secondly, the Court was asked whether the harmful organism needs to be present when the product is used. It noted that the purposes of biocides listed by the BPR includes preventive action, and that such products are "generally used in contexts free of harmful organisms." It also observed that the destruction of harmful organisms themselves is not required by the definition of 'active substance' under the BPR, and that preventive action on the potential habitat of such organisms by removing their "food environment" is sufficient in this regard.

Finally, in light of its reasoning concerning the second question, the Court concluded that the period within which a product takes effect is irrelevant to whether it is a 'biocidal product' or not. In other words, products having a delayed action over time can still be biocides.


The confirmation that probiotic products can be biocides and that preventive "cleaning" action on the harmful organism's habitat can be biocidal may have wide-ranging implications for certain sectors, notably for the cleaning products market, which was the context of this court case. The CJEU Advocate General, for instance, made specific reference to detergent products, observing that these are not excluded from the scope of the BPR and that a product may be considered both as a detergent under Regulation (EC) No 648/2004 on detergents, and as a biocide under the BPR.

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