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Administrative data

Link to relevant study record(s)

Description of key information

The toxicokinetiks and metabolism of menthol and its isomers was examined in an OECD SIDS initial assessment report as follows:

"L-, D/L- and the unspecified menthol isomer are well absorbed by the oral route of exposure and are mainly excreted

as glucuronides. In rats an extensive enterohepatic circulation additionally leads to various hydroxylated degradation

products. Glucuronides and degradation products are eliminated mainly via urine, minor quantities via the faeces." (OECD SIDS 2003)

SIDS Initial Assessment Report 2003 evaluated L, D, and racemic L/D mentols together and gives the rational for a menthol category as follows:

"Category Rationale: The menthols category is comprised of the isomers L-menthol, D-menthol, the racemate and menthol (unspecified

isomers). The menthols can be considered as a category because of their similarity in physico-chemical, toxicological,

ecotoxicological and environmental fate properties.

...

In summary, the available toxicity data indicate very similar toxicity profiles for all of the menthol isomers investigated."

The category justification is documented in a comprehensive 15 page annex to the SIDS Assessment report (Annex 1: Menthols Category JustificationCategory Justification). The annex is attached to the study record entry on the OECD SIDS evaluation as attached background material.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

Menthol glucuronic acid appeared in the urine of rabbits in less than an hour after gavage dosing menthol, and 90 per cent of the conjugated acid was found to be excreted in 6 hours when 2 g of menthol were feed. Even when larger doses were given over 90 per cent of the total amount excreted appeared in the urine during the first 24 hours.

In another study after a single oral administration of 1 g/kg bw of menthol racemic to rabbits, 59 % of the applied test substance was excreted as glucuronide with the urine within 2 d.

Consequently, high bioavailability is documented after oral application

The OECD SIDS Initial Assessment Report concludes on toxicokinetics, metabolism and distriburion:

"L-, D/L- and the unspecified menthol isomer are well absorbed by the oral route of exposure and are mainly excreted

as glucuronides. In rats an extensive enterohepatic circulation additionally leads to various hydroxylated degradation

products. Glucuronides and degradation products are eliminated mainly via urine, minor quantities via the faeces."

IDS Initial Assessment Report 2003 evaluated L, D, and racemic L/D mentols together and gives the rational for a menthol category as follows:

"Category Rationale: The menthols category is comprised of the isomers L-menthol, D-menthol, the racemate and menthol (unspecified

isomers). The menthols can be considered as a category because of their similarity in physico-chemical, toxicological,

ecotoxicological and environmental fate properties.

...

In summary, the available toxicity data indicate very similar toxicity profiles for all of the menthol isomers investigated."