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EC number: 203-377-1
CAS number: 106-24-1
Sensitization to skin by geraniol was evaluated in a local lymph node
assay (LLNA) performed almost similar to OECD guideline 429 (Lalko,
2006). In this study, groups of four female CBA mice were dosed
topically on the dorsum of both ears with 25 µl of geraniol at
concentrations of 2.5%, 5%, 10%, 25% and 50% in 1:3
Ethanol:Diethylphtalate. The dosing occurred daily for three consecutive
days and two days later all mice were injected intravenously by the tail
vein with 250 µl of phosphate buffered saline containing 20 µCi of [3 H]
methyl thymidine. A suspensions of the lymph node cells (LNC) was
prepared and a stimulation index (SI) for each concentration relative to
the concurrent vehicle-treated control was calculated
The EC3 value, or estimated concentration of test material required to
elicit an SI of 3 or more, was derived from the dose-response data by
linear interpolation. As a result, a dose-dependent induction of LNC
proliferation and SI values greater than three at tested concentration
of 25% (SI = 4.8) and 50% (SI = 6.0) were noted. Thus, geraniol could be
regarded as sensitizing to skin.
In two other LLNA studies by the same author, geraniol was also found
sensitizing to skin since the SI values >3 when concentration of 25%,
30% and 50 % were used (Lalko, 2004). In addition, testing with
different vehicles (Diethyl phtalate (DEP); 1:3 Ethanol:DEP; 3:1
Ethanol:DEP; Ethanol) revealed that the strength of the sensitization
response varied with the vehicle, so that in ethanol even a
concentration of 10% also showed a significant positive effect.
In four studies led by the same author LLNA were conducted according to
OECD guideline 429 and guideline EPA OPPTS 870.2600 (Johnson, 2001). In
these studies, concentration of 1%, 3%, 10%, 30% and 50% were tested in
four CBA/CA/Ola/Hsd mice per dose group. Thereby, the four studies used
different vehicles, namely ethanol, diethyl phthalate (DEP), 25%
ethanol/75% diethyl phthalate (DEP) and 75% ethanol/25% diethyl
phthalate (DEP), respectively. In all vehicles, geraniol was found to
result in a SI >3 when concentrations of 30% and 50% geraniol were used.
Thus geraniol was regarded as sensitizing.
Although in two other LLNA studies geraniol was found to have no
sensitizing effects (Lalko, 2006; Johnson, 2003), further eight were
available which found geraniol sensitizing due to induction of LNC
proliferation and SI values greater than three (Kimber, 1989, 1991;
Basketter, 1997, 1999; Haneke, 2001; Isalo, 2001; Johnson, 2003).
Beside the LLNA studies, several other studies were available, which
analyze the sensitization potential of geraniol using the guinea pig
maximization test (GPMT), the open epicutanous test (OET), the Freund’s
complete adjuvant test (FCAT) or the Draize-test (Basketter, 1997, 1999;
Haneke, 2001; Klecak, 1977,1985; Sharp, 1978; Ishihara, 1986; Givaudan,
1977; Quest International, 1989; Buehler, 1992). As a sum of these
studies, geraniol could be regarded as sensitizing to skin while the
strength of sensitizing effects was concentration-dependent and varied
with vehicle used.
This influence of the vehicle was also seen in a study with human where
in a modified Draize-test 10% geraniol in ethanol was sensitizing but
caused no reaction when applied with petrolatum (Marzulli, 1980). In
this study, volunteers received the application of 10 patches which
remained in place for 48-72 hours each. After a rest period of 2 weeks,
the challenge was done consisting of the application of a 72 hour patch
on a new skin site with a nonirritating concentration of geraniol.
Whereas in two of 73 subjects a sensitizing effect was noted when
applied in ethanol, none of 104 subjects were sensitized by geraniol in
Although in other human studies no sensitizing effect could be detected,
these findings were probably results the low concentration of Geraniol
used (Schauder, 1997; Ishihara, 1986; Abifadel, 1992). In contrast,
several studies performed with subjects previously showing allergic
reactions gave positive results in some of these patients, suggesting an
sensitizing potential of geraniol in human (Broeckx ,1987; Rudzki, 1986;
In summary, geraniol could be regarded as sensitizing to skin as
revealed by several animal studies performed according to guidelines. In
addition, several studies with human volunteer, with or without history
of allergic reactions, showed sensitizing effects of geraniol. It is
also worth to mention, that the sensitizing potential turned out to be
concentration-dependent and varied with vehicle.
Migrated from Short description of key information:
Sensitisation: sensitizing in mouse LLNA (OECD 429)
Due to positive results in several LLNA
tests and also positive reactions in human studies, Geraniol should be
classified as sensitizing. However, human data
could not be used to support sub-categorisation either. The
present data on dermal sensitization fulfill the criteria laid down in
regulation (EU) 1272/2008, and therefore, a classification as Skin Sens
1 (H317) is warranted.
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