Limonene
Also known as d-Limonene, (R)-(+)-Limonene, (4R)-1-Methyl-4-(1-methylethenyl)cyclohexene, Limonene
“EU SCCS says: restricted.”
Limonene is a monoterpene (C10H16) and one of the 26 fragrance allergens originally listed in EU Cosmetics Regulation 1223/2009 Annex III (Entry 88, d-Limonene, CAS 5989-27-5) requiring label disclosure when concentration exceeds 0.001% in leave-on or 0.01% in rinse-off products. The SCCS opinion SCCS/1459/11 (2012) classifies (DL)-Limonene as an established contact allergen in humans (++ non-oxidised, +++ oxidised) and identifies it as a prehapten — air oxidation produces limonene hydroperoxides (limonene-1-OOH and limonene-2-OOH) that are markedly more potent sensitisers than parent limonene. SCCS recommends the peroxide content of the oxidised fraction not exceed 10 ppm; EU Annex III enforces a related upstream specification (peroxide value <20 mmoles/L). Patch testing data (Wlodek et al. 2017, Br J Dermatol; Bråred Christensson et al. 2014, Contact Dermatitis) confirm that limonene hydroperoxides at 0.3% in petrolatum elicit positive reactions in 1.7-5.3% of dermatitis patients, ranking among the most common contact allergens. Reg (EU) 2023/1545 expanded the Annex III allergen list to >80 substances but did not change Limonene's Entry 88 thresholds. CIR has NOT published a standalone safety assessment of Limonene as an INCI ingredient — under CIR policy, fragrance-only ingredients are deferred to RIFM (Research Institute for Fragrance Materials), and limonene is discussed only as a constituent within the CIR Citrus-Derived Peel Oils final report (2014/2019) which does not derive a standalone Limonene conclusion.
Naturally occurring monoterpene; the primary constituent (38-95% by weight) of cold-pressed citrus peel oils (lemon, orange, grapefruit, lime, mandarin) used in fragrances and cosmetics for citrus odor.
RIFM has comprehensively assessed dl-limonene (Api et al. 2022, Food Chem Toxicol) supporting safe fragrance use at typical concentrations when peroxide content is controlled.
Kim et al. 2013 (J Toxicol Environ Health B) safety review concluded d-limonene 'may be regarded as a safe ingredient' under current cosmetic regulatory guidelines, with skin irritation as the primary concern at high concentrations.
Acute oral toxicity is very low (LD50 in rats >5 g/kg); has been assessed by FDA as GRAS for food flavoring use.
- · EU Annex III imposes ingredient-level quality specification: peroxide value less than 20 mmoles/L (intended to limit shelf-life autoxidation byproduct accumulation).
Established contact allergen in humans per SCCS/1459/11 Table 13-1: classified ++ for non-oxidised limonene and +++ for oxidised limonene (101-1000 published positive patch test cases). Asterisked as identified in 1999 SCCNFP fragrance allergens opinion.
Prehapten activated by air oxidation (autoxidation) to limonene hydroperoxides (limonene-1-OOH and limonene-2-OOH), which are far more potent sensitisers than the parent compound. SCCS recommends peroxide content of oxidised fraction not exceed 10 ppm.
Mandatory EU label disclosure (Annex III Entry 88) when concentration exceeds 0.001% leave-on or 0.01% rinse-off; ingredient cannot be hidden under generic 'Parfum/Fragrance' declaration above these thresholds.
Limonene hydroperoxide patch testing prevalence: 5.3% positive reactions at 0.3% pet (Wlodek 2017, n=4583); 2.4% (limonene-1-OOH) and 1.7% (limonene-2-OOH) at 0.3% pet (Bråred Christensson 2014, n=763). Ranks among the most common contact allergens in dermatology populations.
No standalone CIR safety assessment exists — CIR defers fragrance-only ingredients to RIFM. Limonene appears only as a constituent in CIR's Citrus-Derived Peel Oils final report (2014/2019), which assessed the peel oils as ingredients, not Limonene as an INCI ingredient.
SCCS/1459/11 — Opinion on Fragrance Allergens in Cosmetic Products (adopted 26-27 June 2012). (DL)-Limonene CAS 138-86-3 listed in Table …
“(DL)-LIMONENE* 138-86-3 ++ (non-ox.);”— sccs_o_102.pdf, p. 107 (Table 13-1: Established contact allergens in humans)
EU Regulation 1223/2009 Annex III (Restricted Substances) — Entry 88: d-Limonene, CAS 5989-27-5; fragrance allergen labeling required abo…
“The presence of the substance must be indicated in the list of ingredients referred to in Article 19(1)(g) when its concentration exceeds: 0,001 % in leave-on products, 0,01 % in rinse-off products”— EU Reg 1223/2009 Annex III, Entry 88