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EC number: 204-677-5
CAS number: 124-07-2
Oral (OECD 401, limit test), rat: LD50 >2000 mg/kg bw
No testing via the inhalation and dermal route was performed due to the
corrosive properties of octanoic acid. However, hazard assessment for
acute dermal toxicity is conducted by means of read-across based on a
Reliable studies on acute dermal toxicity are available for the
following fatty acids category members:
Dermal (OECD 402, limit test), rat: LD50 >2000 mg/kg bw; CAS# 112-05-0,
C9, CAS# 123-99-9, C9d; CAS# 111-20-6, C10d; CAS# 334-48-5, C10
Taken together members of the fatty acids category are not acutely toxic
via the dermal route.
oral toxicity of octanoic acid (CAS#124-07-2) was analyzed in a study
performed under GLP according to OECD guideline 401 (1988). In this
limit test 5 male and 5 female Wistar rats received a dose of 2000 mg/kg
bw octanoic acid by gavage. No signs of systemic toxicity and no change
in body weight gain were observed during the 14 day observation period.
Macroscopic examination of animals at termination revealed only, firm
and/or small white/greyish irregular patches in the forestomach of all
animals. Since no mortality occurred, the LD50 was found to be >2000
another study conducted under GLP in accordance with OECD guideline 401,
5000 mg/kg bw octanoic acid was administered by gavage to 5 male and 5
female Wistar rats (1981). After administration the animals showed
salivation, reduced breathing and activity and reduced state, while in
females also ataxia, lateral position, reduced corneal reflex were
observed. However, all animals were free of symptoms from 24 hours on.
No abnormal findings were noted in body weight gain and at gross
pathology. Since no mortality occurred, the LD50 was found to be >5000
Briggs et al. (1976) reported an oral LD50 value of >10000 mg/kg bw in
on the available data, the oral LD50 value for octanoic acid can be set
as >2000 mg/kg bw.
limited data on acute inhalative toxicity of fatty acids is available
within the fatty acids category.
inhalation risk test was conducted with hexanoic acid (CAS# 142-62-1;
Smyth et al., 1954). No mortality of rats was reported after an 8-hour
exposure to a saturated atmosphere which corresponds to a concentration
of >1.3682 mg/L air based on QSAR calculations (Danish EPA Database,
2004). A LC50 value of 4.1 mg/L was reported for mice exposed to
hexanoic acid for 2 hours (RTECS, 2000). These references are only short
abstracts and therefore not sufficient for hazard assessment.
general, inhalation of fatty acids as vapour is not expected due to the
low vapour pressure of ≤ 0.06 hPa (please refer to category
justification). In case of aerosol forming conditions, risk management
measures and operational conditions including personal protective
equipment have to be implemented in order to avoid inhalation. Short-
and mid-chain fatty acids C6 – C12 are proven irritant/corrosive
substances which cause local effects in the respiratory tract.
to the corrosive properties of octanoic acid no further testing on acute
inhalation toxicity shall be performed in accordance with Column 2 of
Annex VIII, Section 8.5, of Regulation (EC) No 1907/2006 and due to
animal welfare reasons.
No reliable data on acute dermal
toxicity are available for octanoic acid. Testing is not required and
performed as octanoic acid is classified as corrosive to the skin.
However, acute dermal health effects
are predicted from adequate and reliable data for source substances by
read-across to the target substance within the group applying the group
concept in accordance with Annex XI, Item 1.5, of Regulation (EC) No
general prerequisite for systemic toxicity after dermal application is
the permeability of the skin for the applied substance. Although the
dermal penetration of fatty acids is very variable, in general they do
not have significant systemic bioavailability (for details refer to
Section Toxicokinetics, metabolism and distribution).
no acute dermal toxicity by fatty acids is expected as it could be
demonstrated by a LD50
values of >2000 mg/kg bw from adequate and reliable data for the
reference substances C9 fatty acid (nonanoic acid), C9d fatty acid
(azelaic acid), C10 fatty acid (decanoic acid) and C10d fatty acid
acute dermal toxicity of nonanoic acid (CAS# 112-05-1) was examined in
Wistar rats according to OECD guideline 402 and under GLP conditions
(2001). The animals were treated with an occlusive patch for 24 hours.
All animals survived the 14-day observation period following the
application of 2000 mg/kg bw. Clinical signs of toxicity were hunched
posture on the treatment day and the following three days. Skin
reactions due to the corrosive properties of nonanoic acid were noted in
all treated animals and consisted of general erythema, scales and scabs
of the treated skin, generally of slight to moderate grade. In 6 of 10
animals, skin reactions persisted until the end of the observation
period on day 15. Body weights were not affected, and there were no
abnormalities at necropsy after sacrifice on day 15.
In a study similar to OECD guideline
402, azelaic acid (CAS# 123-99-9) was examined for acute dermal toxicity
in rabbits (1964). Dose levels of 1000, 2150, 4640 and 10000 mg/kg bw
were applied to the intact abdominal skin and covered by an occlusive
dressing. After 24 h the dressing and any unabsorbed material was
removed. Except one rabbit at the 4640 mg/kg bw dose level, no
mortalities occurred. According to the authors it is probable that death
in this animal was due to acute enteritis, a common syndrome in
laboratory rabbits. Therefore, the acute dermal LD50 value is >10000
mg/kg bw. The moribund rabbit showed intermittent diarrhea, which was
associated with weight loss. The surviving animals at each dose level
exhibited normal behavior and appearance throughout the 15-day
observation period and gained in body weight. At gross autopsy no
significant gross pathological findings were seen in any animal.
the semiocclusive application of sebacic acid (CAS# 111-20-6) on the
skin of Sprague-Dawley rats for 24 hours according to OECD guideline 402
and under GLP condition, a LD50 of >2000 mg/kg bw was observed (1999).
No mortality occurred during the 14-day observation period and no
clinical signs or body weight abnormalities were noted till the end of
the study. Additionally, no macroscopic findings were evident.
acute dermal toxicity of decanoic acid (CAS# 334-48-5) was investigated
in a limit test according to OECD guideline 402 and in compliance with
GLP (2006). In this study, 5 male and 5 female HanRCC: WIST rats were
treated with the test substance at a dose of 2000 mg/kg bw. The test
substance was dissolved in polyethylene glycol at a concentration of 250
mg/mL and applied onto the clipped skin of the test animals (8 mL/kg bw)
for 24 h under semiocclusive conditions. After exposure, residual test
substance was removed and animals were observed for a period of 14 days.
No deaths occurred and the body weight of all animals was within the
normal range except of one female rat which lost 2.3% of body weight
during the first week after treatment. This female rat showed recovery
during the last week of observation. 4/5 males and 3/5 females were
found slightly or moderately sedated on day 2 of the study after patch
removal. Furthermore, at this time point 3 males and 2 females showed
deep respiration and 3 males and 1 female revealed hunched posture. From
day 3 on no further clinical signs were recorded in any of the treated
rats. After removal of the dressing, slight to moderate erythema was
noted in all animals. The local effects developed into slight to
moderate scaling in all animals and slight scabs were observed in all
animals except one female. Scaling and/or scabs were reversible within
day 5 and 13 in the animals. At necropsy, no findings were noted.
Therefore, the LD50 in male and female rats is > 2000 mg/kg bw.
The dermal absorption (Dermwin v.2.01)
of C9 fatty acid (nonanoic acid) with 0.015 mg/cm²/event, of C9
dicarboxylic fatty acid (azelaic acid) with 0.02 mg/cm²/event of C10
fatty acid (decanoic acid) with 0.009 mg/cm²/event and of C10
dicarboxylic fatty acid (sebacic acid) with 0.012 mg/cm²/event is
greater compared to fatty acids with longer chain lengths (e.g. C12
fatty acid: 0.004 mg/cm²/event, C22 fatty acid: 0.00003 mg/cm²/event or
C18:1 fatty acid: 0.00024 mg/cm²/event) and can therefore be considered
as “worst case assumption” for acute dermal absorption and consequently
for the toxicity of fatty acids.
is being supported by Opdyke
et al. (1978, 1979 and 1981 as cited in Cragg, 2001) reported, that the
acute dermal LD50 in rabbits for octanoic acid (CAS#124 -07 -2),
nonanoic acid (CAS# 112-05-1), decanoic acid (CAS# 334-48-5) and stearic
acid (CAS# 57-11-4) exceeded 5000 mg/kg bw. In addition, the topical
application of commercial grade oleic acid to the skin of guinea pigs at
a concentration of 3000 mg/kg bw produced no deaths (CIR, 1987).
testing of the pure test substance should be avoided in accordance with
Column 2 of Annex VIII, Section 8.5, of Regulation (EC) No 1907/2006 due
to the known corrosive properties of octanoic acid and for animal
dermal exposure can be considered to be sufficiently controlled in
industrial and professional applications since the employees are wearing
gloves and protective clothing due to the corrosive properties of
conclusion, no acute dermal toxicity is expected for octanoic acid
taking into account acute dermal LD50 values > 2000 mg/kg bw for
reference fatty acids (category approach).
S.T. 2001. Aliphatic Carboxylic Acids, Saturated. Patty’s Toxicology
1987. Final Report on the Saftey Assessment of Oleic Acid, Lauric Acid,
Palmitic Acid, Myristic Acid, and Stearic Acid. Journal of the American
College of Toxicology 6(3):321-401
Danish EPA Database, 2004: http://126.96.36.199/
2000 as cited in BUA Report 2000
H. F. Jr. et al.(1954).
RANGE-FINDING TOXICITY DATA - List V. AMA archives of industrial hygiene
and occupational medicine, 10/501/51:61-68.
All available data on acute oral and dermal toxicity of
the members of the fatty acids category do not meet the criteria for
classification according to Regulation (EC) No 1272/2008, and are
therefore conclusive but not sufficient for classification.
There is no adequate and reliable study available for
assessment of acute inhalation toxicity. The results of the available
data within the fatty acids category on acute inhalation toxicity of
hexanoic acid (inhalation risk test in rats) is insufficient for
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