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EC number: 201-195-7 | CAS number: 79-31-2
- 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
No valid data could be identified for assessment of the skin irritating potential of isobutyric acid.
To compensate for this lack of data, information resulting from valeric acid as supporting substance is used as substitute.
For eye irritation, a valid study is available.
Skin irritation / corrosion (supporting substance valeric acid)
Valeric acid was demonstrated to be corrosive in a primary skin irritation study according to OECD TG 404 (Hoechst AG, 1983).
Eye irritation (isobutyric acid)
Isobutyric acid was demonstrated to be corrosive in a valid primary eye irritation test similar to OECD TG 405 (BASF, 1974).
Key value for chemical safety assessment
Skin irritation / corrosion
Link to relevant study records
- Endpoint:
- skin irritation: in vivo
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Justification for type of information:
- REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The reactive group of both substances is the carboxylic acid function, which plays the key role in causing irritating / corrosive effects. For longer chain carboxylic acids, the irritating potential will decrease. C4 and C5 carboxylic acids will cause similar irritating / corrosive effects.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Both substancens are assessed as pure chemicals with negligable impurieties (GC purity >98%). Valeric acid is closely related to isobutyric acid regarding physical-chemical properties.. Both substances are short chain carboxylic acids differing in the length of their carbon chain by only one carbon atom (C5 and C4). Isobutyric asid is a branched carboxylic acud beariug a methyl group in the 2-position. According to chemistry textbook knowledge no impact on the functional group and its dermal effect should be largley affected by this fact. Other physical and chemical properties are quite similar.
3. ANALOGUE APPROACH JUSTIFICATION
Short chain carboxylic acids up to C6 are known to be corrosive. With decreasing chain length number the corrosion potential will increase. For C4 and C5 carboxylic acid a simelar dermal effect regarding irritation and corrosion can be assumed. As the major effect is grounded in the functional caroxylich acid group the influence of the carbon chain is of lower impact and is justified in case of comparison of a C4 to a C5 carboxylic acid. - Reason / purpose for cross-reference:
- read-across source
- Species:
- rabbit
- Strain:
- New Zealand White
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Hoechst AG
- Weight at study initiation: 3.4 - 4.2 kg
- Housing: individually in cages, in air-conditioned rooms
- Diet (e.g. ad libitum): Altrumin 2123 rabbit diet, ad libidum
- Water (e.g. ad libitum): deionized and chlorinated water, ad libidum
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 +/- 2
- Humidity (%): 55 +/- 10
- Photoperiod (hrs dark / hrs light): 12/12 - Type of coverage:
- semiocclusive
- Preparation of test site:
- shaved
- Vehicle:
- unchanged (no vehicle)
- Controls:
- no
- Amount / concentration applied:
- TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 ml on a 2.5 x 2.5 cm patch - Duration of treatment / exposure:
- 60 minutes
- Observation period:
- 0.5-1, 24, 48, 72 hrs after removal of the patch and at day 7 and 14
- Number of animals:
- 3
- Details on study design:
- TEST SITE
- Area of exposure: 2,5 x 2,5 cm
- Type of wrap if used: special wound healing patches, Fa. Baiersdorf AG, Hamburg, covered and fixed with a semiocclusive bandage
REMOVAL OF TEST SUBSTANCE
- Washing (if done): removal of test substance without washing as far as possible
- Time after start of exposure: 60 minutes
SCORING SYSTEM: according to Draize - Remarks on result:
- other: scoring was impeded due severe rigidification, bulging and discoloration of the exposed area
- Interpretation of results:
- Category 1B (corrosive) based on GHS criteria
- Remarks:
- Migrated information R 34 Criteria used for interpretation of results: EU
- Conclusions:
- Classification: corrosive (causes burns)
- Executive summary:
In a primary dermal irritation study according to OECD TG 404, 3 New Zealand White rabbits were exposed dermally to single doses of 0.5 ml of undiluted valeric acid for a one-hour period. Animals then were observed for 14 days. Skin reactions were scored according to OECD TG 404 (method of Draize).
In this study, valeric acid was corrosive to the rabbit's skin after a one-hour contact period, as evidenced by severe skin lesions and scar formation which persisted until the end of the 14-days observation period (Hoechst AG, 1983).
Reference
One hour after removal of the patch, the treated skin of the test animals was green-brown discolored. In the course of observation period the treated skin surface hardened. It became dry and brittle, bulged and changed color via dark red to yellowish brown. After 14 days, severe skin effects were still present. One animal showed peeling of large skin areas, combined with a deep skin lesion and beginning scaring. The skin of one animal was sclerotic and bulged, and the skin of the third animal peeled in large scales.
Scoring for erythema and edema (maximum score = 4)
|
Erythema |
Edema |
||||||||||
|
1 h |
24 h |
48 h |
72 h |
7 d |
14 d |
1 h |
24 h |
48 h |
72 h |
7 d |
14 d |
Rabbit 1 |
* |
* |
* |
* |
* |
* |
3 |
1 |
0 |
0 |
* |
* |
Rabbit 2 |
2 |
2 |
2 |
2 |
* |
0 |
2 |
2 |
2 |
1 |
* |
0 |
Rabbit 3 |
* |
* |
* |
* |
* |
* |
2 |
2 |
1 |
1 |
* |
* |
* scoring not possible due to severe hardening, bulging and discoloration
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed (corrosive)
Eye irritation
Link to relevant study records
- Endpoint:
- eye irritation: in vivo
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Basic data given; comparable to guideline study (deviations: dose only 50 µL, observation period 8 d)
- Principles of method if other than guideline:
- Acute eye irritation test; specific internal BASF standard method
- GLP compliance:
- no
- Species:
- rabbit
- Strain:
- Vienna White
- Details on test animals or tissues and environmental conditions:
- TEST ANIMALS
- Weight at study initiation: male: 2.74 kg; male: 3.06 kg - Vehicle:
- unchanged (no vehicle)
- Controls:
- other: The adjacent eye served as saline control
- Amount / concentration applied:
- TEST MATERIAL
- Amount applied : 0.05 ml - Duration of treatment / exposure:
- 8 days
- Observation period (in vivo):
- 8 days
- Number of animals or in vitro replicates:
- 2
- Irritation parameter:
- cornea opacity score
- Basis:
- mean
- Time point:
- other: 24-48 h
- Score:
- 3
- Max. score:
- 4
- Reversibility:
- not reversible
- Irritation parameter:
- iris score
- Time point:
- other: 8 d
- Score:
- 2
- Max. score:
- 2
- Reversibility:
- not reversible
- Irritation parameter:
- conjunctivae score
- Basis:
- mean
- Time point:
- other: 24 - 48 h
- Score:
- 0.3
- Max. score:
- 4
- Reversibility:
- fully reversible
- Irritation parameter:
- chemosis score
- Basis:
- mean
- Time point:
- other: 24 - 48 h
- Score:
- 2
- Max. score:
- 4
- Reversibility:
- not reversible
- Irritant / corrosive response data:
- irrevesible damage; irritis evolved over time from 24 h (score 0) to day 8 (score 2). Similarly, chemosis developed from score 2 at 24 h to score 3 at 8 d.
- Interpretation of results:
- Category 1 (irreversible effects on the eye) based on GHS criteria
- Remarks:
- Migrated information Criteria used for interpretation of results: EU
- Conclusions:
- In an acute eye irritation test using an internal BASF method, isobutyric acid caused irreversible damage to the rabbit's eye after application of 50 µL test substance. This is only half of the volume required by test guidelines (OECD, EU). Under test conditions completely conform to guideline requirements, the effects observed will be even more pronounced.
- Executive summary:
In a primary eye irritation test, 50 µL of isobutyric acid (purity 99%) was instilled into the conjunctival sac of one eye each of two male Vienna White rabbits. Animals then were observed for 8 days. The original irritation readings were converted to the Draize score at a later date. Readings were taken 24 h, 48 h and 8 d after application of test substance.
The treated eyes showed severe opacity and chemosis, which persisted until the end of the observation period (8 d). Iritis developed over time with highest scores (2) at day 8.
In this study, isobutyric acid was tested to be corrosive to the eye (irreversible effects on the eye - Category 1) based on the irreversibility of the effects observed.
This pre-guideline study bears some deviations from actual test guidelines (amount of test substance, observation period, time of irritation score readings). Nevertheless, the data are assessed to be sufficiently valid to represent the eye damaging potential of isobutyric acid as the correct amount of test substance would result in even more pronounced effects. Using available results conforms to the tiered testing and evaluation strategy for eye irritation/corrosion and further testing can be avoided.
Reference
Descriptive scores of the raw data have been converted to Draize numerical scores.
Animal |
Reading |
Opacity |
Iritis |
Redness |
Chemosis |
Comment |
1 |
24 h |
3 |
0 |
0 |
2 |
|
2 |
24 h |
3 |
0 |
0 |
2 |
pus |
1 |
48 h |
3 |
0 |
1 |
2 |
|
2 |
48 h |
3 |
0 |
0 |
2 |
pus |
1 |
8 d |
3 |
2 |
not reported |
3 |
|
2 |
8 d |
2 |
2 |
not reported |
3 |
|
mean |
24 - 48 h |
3 |
0 |
0.3 |
2 |
|
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed (irreversible damage)
Respiratory irritation
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
Skin irritation / corrosion
For isobutyric acid, no valid studies concerning skin irritation / corrosion could be identified. There are only publications of low reliability (RL3 or 4).
To assess the skin irritation / corrosion potential of isobutyric acid, data for valeric acid as supporting substance will be used based on following reasons.
Valeric acid is closely related to isobutyric acid. Both substances are short chain carboxylic acids differing in the length of their carbon chain by only one carbon atom (C5 and C4). Physical and chemical properties will be quite similar. The reactive group of both substances is the carboxylic acid function, which plays the key role in causing irritating / corrosive effects. Short chain carboxylic acids up to C6 are known to be corrosive. For longer chain carboxylic acids, the irritating potential will decrease. C4 and C5 carboxylic acids will cause similar irritating / corrosive effects. Thus, it is justified to use valeric acid as supporting substance in the evaluation of irritation / corrosion potential of isobutyric acid.
Supporting substance valeric acid
The irritation / corrosion potential of valeric acid was studied in a valid primary skin irritation test (Hoechst AG, 1983)
Hoechst AG, Rupprich 1983
In a primary dermal irritation study according to OECD TG 404, 3 New Zealand White rabbits were exposed dermally to single doses of 0.5 ml of undiluted valeric acid for a one-hour period. Animals then were observed for 14 days. Skin reactions were scored according to OECD TG 404 (method of Draize).
In this study, valeric acid was corrosive to the rabbit's skin after a one-hour contact period, as evidenced by severe skin lesions and scar formation, which persisted until the end of the 14-days observation period (Hoechst AG, 1983).
Corrosion / irritation potential of isobutyric acid
Based on the result for valeric acid, isobutyric acid is assessed also to be corrosive.
Eye irritation
For the assessment of the eye irritating potential of isobutyric acid, one valid study is available (BASF AG, 1974). In the study of Smyth (1962), the method and the scoring system used are greatly different from actual guideline requirements. Thus, results are not suited to assess the irritation / corrosion potential or the tested substances.
The BASF study (pre-guideline study) bears some deviations from actual test guidelines (amount of test substance, observation period, time of irritation score readings). Nevertheless, the data are assessed to be sufficiently valid to represent the eye damaging potential of isobutyric acid, as the correct amount of test substance would result in even more pronounced effects. Using available results conforms to the tiered testing and evaluation strategy for eye irritation / corrosion and further testing can be avoided.
BASF AG 1974
In a primary eye irritation test, 50 µL of isobutyric acid (purity 99%) was instilled into the conjunctival sac of one eye each of two male Vienna White rabbits. Animals then were observed for 8 days. The original irritation readings were converted to the Draize score at a later date. Readings were taken 24 h, 48 h and 8 d after application of test substance.
The treated eyes showed severe opacity and chemosis, which persisted until the end of the observation period (8 d). Iritis developed over time with highest scores (2) at day 8.
In this study, isobutyric acid was tested to be corrosive to the rabbit's eye based on the irreversibility of the effects observed.
Effects on skin irritation/corrosion: corrosive
Effects on eye irritation: corrosive
Justification for classification or non-classification
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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