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EC number: 205-550-7 | CAS number: 142-62-1
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Endpoint summary
Administrative data
Description of key information
Skin irritation (OECD 404): corrosive (Kästner, 1984)
Eye irritation (OECD 437), 50%: corrosive (Lütkenhaus, 2012)
Key value for chemical safety assessment
Skin irritation / corrosion
Link to relevant study records
- Endpoint:
- skin irritation: in vivo
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 22 Oct - 13 Nov 1984
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- guideline study with acceptable restrictions
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 404 (Acute Dermal Irritation / Corrosion)
- Version / remarks:
- 1981
- Deviations:
- yes
- Remarks:
- limited data; occlusive dressing
- GLP compliance:
- not specified
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Weight at study initiation: mean weight 3294 g - Type of coverage:
- occlusive
- Preparation of test site:
- shaved
- Vehicle:
- unchanged (no vehicle)
- Controls:
- not specified
- Amount / concentration applied:
- 0.5 mL
- Duration of treatment / exposure:
- 4 h
- Observation period:
- 21 days
Reading time points: immediately, 1, 24, 48 and 72 h and 6, 8, 10, 13, 15, 17 and 21 days after patch removal - Number of animals:
- 5
- Details on study design:
- TEST SITE
- Area of exposure: dorsal area (3 cm x 3 cm)
The substance was applied on shaved skin and covered with a linen lobule.
- Type of wrap if used: polyethylene foil wrapped with an elastic bandage
REMOVAL OF TEST SUBSTANCE
- Washing: The skin was cleaned of residual test substance.
- Time after start of exposure: 4 h
SCORING SYSTEM: Draize scoring system
Body weights of the rabbits were determined 7, 14 and 21 days after initiation of the study. - Irritation parameter:
- other: necrosis and scar tissue
- Basis:
- other: all 5 animals
- Time point:
- other: 21 days
- Reversibility:
- not reversible
- Remarks on result:
- other: scar tissue was observed at the treated sites in all animals at the end of the observation period, indicating irreversible skin damage
- Irritation parameter:
- erythema score
- Time point:
- 24/48/72 h
- Remarks on result:
- other: scores were not given
- Irritation parameter:
- edema score
- Time point:
- 24/48/72 h
- Remarks on result:
- other: scores were not given
- Irritant / corrosive response data:
- Immediately after removal of the dressing, intensive erythema and edema was observed. The edema had disappeared after seven days, the erythema however persisted and passed into a full thickness necrosis.
10 days after initiation of the study eschar started to separate from treated skin. Another 7 days later eschar was completely separated from skin. 21 days after treatment a red scar tissue with single eschar rest had developed. Around the scar tissue, an intensified growth of hair appeared and on the treated skin area, there were just single flocci.
Based on the findings the test material is considered corrosive under the experimental conditions chosen. Corrosive effects are expected even if the study would had been conducted under semiocclusive conditions: As the test material has a very low vapour pressure, evaporating of the test material from the skin through the semiocclusive dressing is rather unlikely. - Other effects:
- The body weights of the animals showed normal growth and were upto 3644 g at the end of the study.
- Interpretation of results:
- other: classification as Skin Corr. 1C, H314 required according to Regulation (EC) No 1272/2008
- Conclusions:
- CLP: Skin Corr. 1C, H314
Reference
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed (corrosive)
Eye irritation
Link to relevant study records
- Endpoint:
- eye irritation: in vitro / ex vivo
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 14 Dec 2011 - 24 Jan 2012
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP - Guideline Study
- Qualifier:
- according to guideline
- Guideline:
- other: OECD Guideline 437: Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants (adopted 7 Sept 2009)
- GLP compliance:
- yes (incl. QA statement)
- Remarks:
- BAYERISCHES LANDESAMT FÜR GESUNDHEIT UND LEBENSMITTELSICHERHEIT, LANDESINSTITUT FÜR ARBEITSSCHUTZ UND PRODUKTSICHERHEIT, München, Germany
- Species:
- other: cattle
- Strain:
- not specified
- Details on test animals or tissues and environmental conditions:
- IDENTIFICATION OF THE SOURCE OF THE EYES, STORAGE AND TRANSPORT CONDITIONS
- Source: Attenberger Fleisch GmbH & Co. KG, Munich, Germany
- Date of eye collection: 14 Dec 2011
- Transport medium and temperature conditions: Hanks´ Balanced Salt Solution (HBSS) containing penicillin/streptomycin on ice
PREPARATION OF THE EYES (BEFORE EXPOSURE)
- Eyes free of defects (scratches, neovascularisation): yes
- Dissection of the eyes and treatment: Corneas were dissected with a 2 to 3 mm rim of sclera. Isolated corneas were mounted in cornea holders.
- Type of cornea holder used: MC2, Clermont, France
- Description of the cornea holder: the cornea holders consist of an anterior and a posterior compartment, which interface with the epithelial and endothelial sides of the cornea.
- Test medium and temperature conditions used in the cornea holder: RPMI 1640 without phenol red supplemented with 1% [v/v] fetal bovine serum and 2 mM L-glutamine
- Equilibration time: 1 h at 32 ± 1 °C in a water bath
- Quality check of the equilibrated corneas: initial opacity measurement; corneas with an initial opacity above 7 in the opacitometer were discarded.
DETERMINATION OF THE INITIAL OPACITY
- Method: Corneal opacity was determined by the amount of light transmission through the cornea via an opacitometer.
- Specification of the device: MC2, Clermont, France - Vehicle:
- other: sesame oil
- Controls:
- other: 3 eyes each for the two negative controls (sesame oil and physiological saline 0.9% NaCl); 3 eyes for the positive control (70% ethanol)
- Amount / concentration applied:
- - Amount(s) applied in the test: 750 µL
- Concentration (if solution): 50% - Duration of treatment / exposure:
- 10 min at 32 ± 1 °C
- Observation period (in vivo):
- not applicable
- Number of animals or in vitro replicates:
- 3 eyes for the test item
- Details on study design:
- TEST CONDITIONS
- Short description of the method used: closed-chamber method.
The test substance or control substances were introduced into the anterior.
POST-EXPOSURE TREATMENT
- Removal of the test substance: Example: The test substance was removed after 10 min incubation and the epithelium washed at least three times. for the corneas treated with sesame oil as vehicle, the chambers were opened and the corneas were rinsed with 100 mL MEM.
- Medium for washing the corneas: MEM containing phenol red
- Medium for final rinsing: Example: RPMI 1640 without phenol red
DETERMINATION OF THE FINAL OPACITY
- Method: Corneal opacity was determined by the amount of light transmission through the cornea via an opacitometer.
- Time of determination: After refilling fresh RPMI 1640 without phenol red into the anterior chamber, the final opacity was measured after 2 hours incubation at 32 ± 1 °C
- Specification of the device: MC2, Clermont, France
DETERMINATION OF THE CORNEAL PERMEABILITY:
- Method: Sodium fluorescein solution was added to the anterior chamber of the cornea holder while the posterior chamber was filled with fresh medium. The amount of sodium fluorescein that crosses into the posterior chamber was quantitatively measured via UV/VIS spectrophotometry at 490 nm recorded as optical density (OD490).
- Amount and concentration of the dye: 1 mL sodium fluorescein solution (4 mg/mL)
- Incubation time: 90 min at 32 ± 1 °C - Irritation parameter:
- in vitro irritation score
- Remarks:
- mean of all 3 eyes
- Run / experiment:
- 10 min exposure with the test substance
- Value:
- 143.61
- Vehicle controls validity:
- valid
- Negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Remarks:
- 62.51
- Irritation parameter:
- other: opacity
- Remarks:
- mean of all 3 eyes
- Run / experiment:
- 10 min exposure with the test substance
- Value:
- 114
- Vehicle controls validity:
- valid
- Negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Remarks:
- 52.67
- Irritation parameter:
- other: permeability
- Remarks:
- mean of all 3 eyes
- Run / experiment:
- 10 min exposure with the test substance
- Value:
- 1.974
- Vehicle controls validity:
- valid
- Negative controls validity:
- not applicable
- Positive controls validity:
- valid
- Remarks:
- 0.656
- Other effects / acceptance of results:
- For hexanoic acid at a concenration of 50% (v/v) an in vitro irritation score of 143.61 was calculated and therefore the test substance is considered as severe eye irritant.
- Interpretation of results:
- corrosive
- Remarks:
- Criteria used for interpretation of results: EU
- Conclusions:
- CLP: Cat. 1, H318
Reference
Table 1: Opacity values
Parameter |
Initial opacity |
Final opacity |
Opacity change |
Mean opacity change of NC |
Corrected opacity change |
Mean opacity value |
Negative control (0.9% NaCl) |
4 |
5 |
1 |
2.33 |
- |
- |
4 |
9 |
5 |
||||
4 |
5 |
1 |
||||
Negative control (sesame oil) |
4 |
7 |
3 |
2.33 |
- |
- |
4 |
5 |
1 |
||||
5 |
8 |
3 |
||||
Test substance |
3 |
124 |
121 |
- |
118.67 |
114.00 |
3 |
112 |
109 |
106.67 |
|||
3 |
122 |
119 |
116.67 |
|||
Positive control |
5 |
56 |
51 |
- |
48.67 |
52.67 |
5 |
58 |
53 |
50.67 |
|||
5 |
66 |
61 |
58.67 |
Table 2: Permeability values (optical density (OD) at 490 nm)
Parameter |
OD490 change |
Mean OD490 change of NC |
Corrected OD490 change |
Mean OD490 value |
Negative control (0.9% NaCl) |
0.003 |
0.004 |
- |
- |
0.009 |
||||
0.001 |
||||
Negative control (sesame oil) |
0.000 |
0.004 |
- |
- |
0.003 |
||||
0.008 |
||||
Test substance |
1.842 |
1.977 |
1.838 |
1.974 |
2.086 |
2.082 |
|||
2.004 |
2.00 |
|||
Positive control |
0.400 |
0.661 |
0.396 |
0.656 |
0.770 |
0.766 |
|||
0.812 |
0.808 |
Table 3: In Vitro Irritancy Score (IVIS) values
|
IVIS |
Mean IVIS |
Negative control (0.9% NaCl) |
1.05 |
2.40 |
5.14 |
||
1.02 |
||
Negative control (sesame oil) |
3.00 |
2.39 |
1.05 |
||
3.12 |
||
Test substance |
146.24 |
143.61 |
137.90 |
||
146.67 |
||
Positive control |
54.61 |
62.51 |
62.16 |
||
70.79 |
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed (irreversible damage)
Respiratory irritation
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
Skin
in vivo
Skin irritation by hexanoic acid was evaluated in a study performed according to OECD Guideline 404, where 0.5 mL of hexanoic acid was applied to the shaved skin of five New Zealand White animals under occlusion for 4 hours (Kästner, 1984). Immediately after removal of the plaster, intensive erythema and edema was observed. The edema had disappeared after seven days; the erythema, however, persisted and passed into a full thickness necrosis. 10 days after initiation of the study eschar started to separate from treated skin. Another 7 days later eschar was completely separated from skin. 21 days after treatment a red scar tissue with single eschar rest had developed. Around the scar tissue, an intensified growth of hair appeared and on the treated skin area, there were just singleflocci[AWE1] indicating the full thickness destruction of all epidermal layers. Based on the findings the test material is considered corrosive under the experimental conditions chosen. Corrosive effects are expected even if the study would had been conducted under semiocclusive conditions as the test material has a very low vapour pressure so that evaporating of the test material from the skin through the semiocclusive dressing is rather unlikely.
In addition Smyth et al. (1954) also reported strong skin injury (score 6) after application of hexanoic acid to the rabbit skin for 24 hours. In the used 10-grade ordinal scale the score of 6 indicates necrosis from the undiluted test substance.
in vitro
In the ECVAM International Validation study on in vitro tests for skin corrosivity during 1996 and 1997, hexanoic acid was one of 60 test chemicals (Fentem et al., 1998). The tests evaluated were inter alia, EPISKINTM, the in vitro membrane barrier test method for skin corrosion (CORROSITEX), and the rat skin transcutaneous electrical resistance (TER) assay.
In all three assays hexanoic acid revealed corrosive properties. A corrosive result was also obtained in a TER assay performed by Whittle et al. (1996), in which the application of hexanoic acid for 24 h to rat skin discs resulted in a TER value of 1.2 kΩ, which was well below the cut-off value for rat tissues of 5 kΩ. Whittle et al. (1996) also exposed human skin tissue samples to hexanoic acid for 24 h and evaluated the vitro skin corrosivity potential via TER measurements. The TER was decreased below 11 kΩ (cut-off-value for human tissues) in 5 out of 9 human tissue preparations.
Hexanoic acid in concentrations of 50, 60 and 70% (v/v) was tested in a human skin model test according to OECD Guideline 431 (EpiDerm) under GLP conditions (Lehmeier, 2011). Hexanoic acid was diluted to the corresponding concentrations with sesame oil. 50 µL of the test items were topically applied 3 minutes and 1 hour to a three-dimensional human skin model, comprising a reconstructed epidermis with a functional stratum corneum. Afterwards the cell viability was assessed via MTT reduction assay.
For hexanoic acid at a concentration of 70%, the mean relative tissue viability was decreased below 50% (37%) after 3 min treatment compared to the negative control (distilled water) and thus showed corrosive effects. 50% and 60% hexanoic acid showed no clear corrosive effects. Since, the relative mean tissue viability after 3 min treatment was ≥ 50% (72% for 50% hexanoic acid and 57% for 60% hexanoic acid, respectively) and after 1-hour treatment ≥ 15% (15% for 50% and 60% hexanoic acid), hexanoic acid at concentrations of 50% and 60% are considered as non-corrosive. Hexanoic acid led to a dose-dependent colouring of the tissues after the 3 min and 1-hour treatment. To assess the influence of this extractable colour and to avoid false-negative results, the “Check-method to detect coloring test substance ability to stain tissues” according to the L´Oréal Standard Operating Procedure EpiSkinTM skin irritation method was performed in a follow-up study for 50% and 60% hexanoic acid. The non-specific colour for 50% and 60% hexanoic acid was below 5% (2.9% for both test items after 3 min and 2.7% and 3.0% in the 1-hour experiments, respectively) and therefore no correction of the results are necessary according to the L´Oréal Standard Operating Procedure (Lehmeier, 2011).
Human data
Hexanoic acid at concentrations of 0.5 M (5.8% (w/v)) and 1 M (11.6% (w/v)) were applied daily under occlusive patch tests to human skin until detectable erythema appeared or until the experiment terminated after 10 consecutive days of applications (Stillman et al., 1975). Daily dermal application of 1 M hexanoic acid resulted in erythematous responses in 7 out of 10 subjects until the termination of the study and one out of 10 volunteers showed erythema after daily dermal application of 0.5 M hexanoic acid. Based on these results, hexanoic acid is considered to produce skin irritation in humans after chronic exposure in a concentration-dependent manner.
In conclusion, the results of in vivo and in vitro studies demonstrated, that hexanoic acid is corrosive. Concentrations of ≤ 60% hexanoic acid are non-corrosive on a regulatory point of view.
Eye
in vivo
Smyth et al. (1954) reported strong eye injury (score 8) after application of hexanoic acid to rabbit eyes. In the 10-grade ordinal scale used, the grade 5 describes severe burn from 0.005 mL of the undiluted test item and grade 10 indicates severe burn from 0.5 mL of a 1% solution.
in vitro
The eye irritancy potential of hexanoic acid in a concentration of 50% was investigated in the bovine corneal opacity and permeability assay (BCOP) according to OECD Guideline 437 under GLP conditions (Lütkenhaus, 2012). 50% hexanoic acid in sesame oil was applied to the epithelial surface of three cattle corneas for 10 min at 32 ± 1 °C by addition to the anterior chamber of the corneal holder. The corneas were washed and the damage by the test substance was assessed two hours later by quantitative measurement of changes in corneal opacity with an opacitometer. In addition the permeability of the corneas was measured with a visible light spectrophotometer after incubation of the corneas with sodium fluorescein solution for 90 min. The results of the opacity and permeability measurement resulted in an in vitro irritation score (IVIS) of 143.61. Test substances with an IVIS ≥ 55.1 are regarded as severe eye irritants.
No further testing is required in accordance with Column 2 of Annex VIII, Section 8.2.1, of Regulation (EC) No 1907/2006, since hexanoic acid is classified as corrosive to skin and the registrant classifies hexanoic acid as severe eye irritant.
Justification for classification or non-classification
The available data on irriration / corrosion of hexanoic acid at a concentration > 60% meet the criteria for classification as Skin Cat. 1C (H314) according to Regulation (EC) 1272/2008.
The following concentration limits are assigned:
CLP (Regulation (EC) 1272/2008)
>60% Skin Cat. 1C;H314, Eye Cat.1; H318
≥ 3% - ≤60% Eye Cat.1;H318 and Skin Cat. 2;H315
≥1% - < 3% Eye Cat. 2;H319 and Skin Cat. 2;H315
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