Statement concerning the review of the approval of the basic substances chitosan and chitosan hydrochloride when used in plant protection

Abstract

The European Commission asked EFSA to provide an opinion according to Article 23(6) of Regulation (EC) No 1107/2009, in conjunction with Article 29 of Regulation (EC) No 178/2002, regarding the approved plant protection uses of chitosan and chitosan hydrochloride as basic substances. The Panel on Plant Protection Products and their Residues (PPR) was not provided with new dossiers but collated available scientific and technical knowledge and used a weight of evidence approach and experts' judgement for its appraisal. The statement has considered the possibility for extrapolation of the toxicological properties between chitosan and chitosan hydrochloride, and whether both substances can be expected to be of no toxicological concern; a comparison between the estimated levels of chitosan and chitosan hydrochloride resulting from the approved uses as basic substances and the level of chitosan expected to naturally occur in the environment. This last comparison served to verify whether the approved uses as basic substances might lead to an exceedance of the expected natural background levels in any of the environmental compartments (quantitative for the soil compartment and (semi)quantitative for the freshwater compartment); and accordingly, whether there was a need to advise on the safety of chitosan and chitosan hydrochloride to non-target species occurring in the impacted environmental compartments. Overall, the PPR Panel concluded that toxicological properties can be extrapolated between chitosan and chitosan hydrochloride and that no toxicological concerns were identified. The estimated levels of chitosan and chitosan hydrochloride in the environment following application in accordance with their approved uses as basic substances would be within the same range, or below, the expected natural background exposure levels in soil and freshwaters. Considering the available ecotoxicological data and the environmental fate assessment, further consideration in relation to the safety to non-target organisms was considered not necessary. Missing information alongside related uncertainties have been identified and considered in the overall weight of the evidence.

Keywords: basic substances; chitin; chitosan; chitosan hydrochloride; environmental fate; mammalian toxicology; natural waters; pesticide; soil.

FIGURE 1

Chitin chemical structure (CAS number: 1398‐61‐4) (fully acetylated).

FIGURE 2

Chitosan chemical structure (CAS number: 9012‐76‐4).

FIGURE 3

Chitosan hydrochloride chemical structure (CAS number: 70694‐72‐3).

FIGURE 4

Presumed route of bioshynthesis of chitosan (adapted from Ghormade et al., 2017). (‘EC’ referring to the ‘Enzyme Commission’ number).

FIGURE 5

General scheme of chitin degradation and contribution to the global N and C‐cycles (adapted from Beier & Bertilsson, 2013).

FIGURE 6

Presumed scheme of microbial degradation of chitin (adapted from Gooday, 1990). GlcNAc, N‐acetyl‐d‐glucosamine.