Fatty acids, C16-18 (even numbered) saturated and C16-20 (even numbered) unsaturated, lithium salts

Endpoint summary

Description of key information

Skin irritation results: In vitro studies on dermal irritation have been conducted on C14, C16, and C18 fatty acid lithium salts. No irritant responses leading to classification were observed.

Eye irritation results: The irritant/corrosivity properties of fatty acids are chain length dependent, where the lower carbon chain length < C9 are corrosive, C10 – C12 are irritant and C14 and above are non-irritant. In vitro and in vivo studies on ocular irritation were conducted on C14, C16 and C18 fatty acid lithium salts. No classifiable irritant responses were observed for C16 and C18 fatty acid lithium salts, but irritation was seen for C14 (lithium myristate). This result was not read across to the category since the C16 and C18 results were negative. As this UVCB contains less than 3% of C12-C14 fatty acid lithium salts, the overall UVCB is not classified according to the EU CLP mixture toxicity rules.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

The study was performed between 14 February 2012 and 20 February 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study, available as an unpublished report.

Justification for type of information:

See IUCLID section 13 for read across justification

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 439 (In Vitro Skin Irritation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

other: EPISKIN (TM) human epidermis model

Strain:

other: not applicable

Details on test animals or test system and environmental conditions:

Not applicable

Type of coverage:

other: topical

Preparation of test site:

other: not applicable

Vehicle:

unchanged (no vehicle)

Controls:

other: not applicable

Amount / concentration applied:

- Treatment group: Approximately 10 mg lithium myristate was applied topically, ensuring an even covering, to the epidermis surface which had previously been moistened with 5 µL sterile, distilled water.
- Negative control: 10 µL Dulbecco's Phosphate Buffered Saline (DPBS) with Ca++ and Mg++
- Positive control: 10 µL Sodium Dodecyl Sulphate (SDS) at 5% w/v aqueous solution spread over entire surface of the epidermis using a pipette tip and re-spread after 7 minutes.

Duration of treatment / exposure:

- Treatment period: 15 minutes
- Post-exposure incubation: At the end of the exposure period, tissues were rinsed and incubated for 42 hours, at 37°C and 5% CO2 in air, in wells containing 2 mL maintenance media.

Observation period:

No applicable

Number of animals:

Not applicable

Details on study design:

- Approximately 10 mg of lithium myristate was applied to the epidermis surface, which had been previously moistened with 5µL sterile, distilled water. At the end of the 15 minute exposure period, each tissue was removed and rinsed with DPBS with Ca++ and Mg++ . The tissues were then incubated for 42 hours at 37°C and 5% CO2 in air, in wells containing 2 mL maintenance media.
- After incubation, the viability (cytotoxicity) of the treated tissues were compared to the negative control tissues, by means of a colourimetric MTT reduction assay. If the mean tissue viability is ≤50%, the substance is considered to be irritant.

Irritation / corrosion parameter:

other: other: Optical density at 540 nm

Value:

0.948

Remarks on result:

other:

Remarks:

Basis: mean. Time point: After a 15 minute exposure. Remarks: Negative control item. (migrated information)

Irritation / corrosion parameter:

other: other: Optical density at 540 nm

Value:

0.052

Remarks on result:

other:

Remarks:

Basis: mean. Time point: After a 15 minute exposure. Remarks: Positive control item. (migrated information)

Irritation / corrosion parameter:

other: other: Optical density at 540 nm

Value:

0.96

Remarks on result:

other:

Remarks:

Basis: mean. Time point: After a 15 minute exposure. Remarks: Test item. (migrated information)

Irritation / corrosion parameter:

other: other: Relative viability (%)

Value:

100

Remarks on result:

other:

Remarks:

Basis: mean. Time point: After a 15 minute exposure. Remarks: Negative control item (set at 100%). (migrated information)

Irritation / corrosion parameter:

other: other: Relative viability (%)

Value:

5.5

Remarks on result:

other:

Remarks:

Basis: mean. Time point: After a 15 minute exposure. Remarks: Positive control item. (migrated information)

Irritation / corrosion parameter:

other: other: Relative viability (%)

Value:

101.3

Remarks on result:

other:

Remarks:

Basis: mean. Time point: After a 15 minute exposure. Remarks: Test item. (migrated information)

Other effects / acceptance of results:

- Viability: The relative mean viability of the treated tissues was 101.3% after a 15-minute exposure period, with standard deviation of 5.2%
- Optical density: The mean optical density of the treated tissues at 540 nm was 0.96
- Conclusion: Lithium myristate is considered to be non-irritant using the EPISKIN (TM) human epidermis model (viability >50%)
- Positive control: The relative mean tissue viability was 5.5% relative to the negative control and the standard deviation was 3.3%
- Negative control: The mean optical density was 0.948 and the standard deviation was 5.0%

- Direct MTT reduction: The MTT solution containing lithium myristate did not turn blue, indicating that lithium myristate did not directly reduce MTT

- The positive and negative control acceptance criteria were satisfied according to the protocol criteria. The standard deviation of the triplicate treated tissues was 5.2% and hence the test item acceptance criterion was also satisfied.

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Lithium myristate is considered to be non-irritant using the EPISKIN (TM) human epidermis model.

Executive summary:

Lithium myristate is considered to be non-irritant using the EPISKIN (TM) human epidermis model. The skin irritation potential of lithium myristate was evaluated using EPISKIN (TM) reconstructed human epidermis model after a treatment period of 15 minutes followed by a post-exposure period of 42 hours using a colourimetric MTT reduction assay following OECD guideline 439 in an experimental proprietary study (Harlan 2013). The quality criteria required for the acceptance of results in the test were satisfied and the study is considered relevant and reliable for use.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vivo

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

26 March 2012 to 30 April 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study, available as an unpublished report.

Justification for type of information:

See IUCLID section 13 for read across justification

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

- Test animals: Two New Zealand White (Hsdlf:NWZ) strain rabbits were supplied by Harlan Laboratories UK Ltd., Leicestershire, UK. At test initiation, rabbits were twelve to twenty weeks old and weighed 2.25 to 3.13 kg. After at least five days acclimatisation, a number unique within the study was written in black, indelible marker-pen on the inner surface of the ear and on the cage label. Immediately prior to test initiation, both eyes of the provisionally selected rabbit were examined for evidence of occular irritation or defect with a standard opthalmoscope and only animals free of ocular damage were used.
- Housing: Animals were housed individually in suspended cages with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.
- Feeding: Throughout the study, animals were allowed free access to mains drinking water and food (2930 Teklad Global Certified Rabbit diet supplied by Harlan Laboratories UK Ltd., Oxon, UK). The diet and drinking water were considered not to contain any contaminant of a level that might have affected the purpose of the study.
- Environmental conditions: The temperature and relative humidity were set to achieve limits of 17 to 23°C and 30 to 70% respectively. Any occasional deviations from these targets were considered not to have affected the purpose of the study. The rate of air exchange was at least fifteen changes per hour. The lighting was controlled by a time switch to give twelve hours continuous light (06:00-18:00) and twelve hours darkness.

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

- Volume of application: 0.1 mL lithium myristate (found to weigh approximately 68 mg after gently compacting the required volume into an adapted syringe) was placed into the conjunctival sac of the right eye.

Duration of treatment / exposure:

- Duration of treatment: Single administration, no irrigation used
- Duration of observation: 14 days

Observation period (in vivo):

- Observation period: 14 days. After approximately 1, 24, 48 and 72 hours after application, the ocular damage/irritation was assessed according to Draize JH (1977) "Dermal and eye toxicity tests" in Principles and procedures for evaluating the toxicity of household substances, National Academy of Sciences, Washington DC, pp. 48-49 and any other ocular effects or clinical signs of toxicity were also noted. The reversibility of ocular effects was assessed by observations on days 7 and 14. Individual bodyweights were recorded on days 0 and at test termination.

Number of animals or in vitro replicates:

- Number of animals: 2

Details on study design:

- Irrigation of eyes: No evidence of residual test item in the treated eyes; no rinsing required.
- Interpretation methods: The numerical values corresponding to each animal, tissue and observation time were recorded using the Draize evaluation scale (Draize J H, 1977, "Dermal and eye toxicity tests" in: Principles and procedures for evaluating the toxicity of household substances, National Academy of Sciences, Washington DC). Using the numerical data obtained for cornea, iris and conjunctivae scores, the irritation potential was determined according to Regulation (EC) No 1272/2008, Relating to Classification, Labelling and Packaging of Dangerous Substances.

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

1

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 14 days

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0.7

Max. score:

2

Reversibility:

fully reversible within: 14 days

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 days

Irritant / corrosive response data:

- Conjunctivae: Moderate conjunctival irritation was noted in the treated eyes of both rabbits one hour after treatment and at the 24, 48 and 72 hour observations with minimal conjunctival irritation noted at the 7 day observation.
- Iris: Iridial inflammation was noted in the treated eyes of both rabbits one hour after treatment and at the 24 and 48 hour observations and persisted in one treated eye at the 72 hour observation.
- Cornea: Scattered or difuse corneal opacity was noted in the treated eyes of both animals one hour after treatment and at the 24, 48 and 72 hour observations and persisted in one treated eye at the 7 day observation.
- Reversibility: Treated eyes of both rabbits appeared normal at the 14 day observation.
- Result: Irritating to eyes (category 2) according to Regulation (EC) No. 1272/2008

Other effects:

- Bodyweight: Both animals showed expected bodyweight gain during the study.

Individual Scores and Individual Total Scores for Ocular Irritation

Rabbit number and sex	71855 Male						71855 Male
	IPR = 2						IPR = 2
Time after treatment	1 hour	24 hour	48 hour	72 hour	7 day	14 day	1 hour	24 hour	48 hour	72 hour	7 day	14 day
CORNEA
E = Degree of Opacity	1	1	1	1	1	0	1	1	1	1	0	0
F = Area of Cornea Involved	1	2	2	2	1	0	1	1	1	1	0	0
Score (E x F) x 5	5	10	10	10	5	0	5	5	5	5	0	0
IRIS
D	1	1	1	1	0	0	1	1	1	0	0	0
Score (D x 5)	5	5	5	5	0	0	5	5	5	0	0	0
CONJUNCTIVAE
A = Redness	2	2	2	2	1	0	2	2	2	2	1	0
B = Chemosis	2	2	2	2	1	0	2	2	2	2	1	0
C = Discharge	2	2	2	1	0	0	2	2	2	1	0	0
Score (A + B + C) x 2	12	12	12	10	4	0	12	12	12	10	4	0
Total score	22	27	27	25	9	0	22	22	22	15	4	0

Individual Total Scores and Group Mean Scores for Ocular Irritation

Time after treatment	1 hour	24 hour	48 hour	72 hour	7 day	14 day
71855 Male	22	27	27	25	9	0
17923 Male	22	22	22	15	4	0
Group Total	44	49	49	40	13	0
Group Mean Score	22.0	24.5	24.5	20.0	6.5	0.0

Interpretation of results:

irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Lithium myristate is classified as irritating to eye (category 2) according to Regulation (EC) No. 1272/2008.

Executive summary:

Lithium myristate is classified as irritating to eye (category 2) according to Regulation (EC) No. 1272/2008. The potential irritiancy of lithium myristate to the eye of the New Zealand white rabbit was assessed following OECD guideline 405 (adopted 2002) in a proprietary, experimental study (Harlan 2012). A single application of 0.1 mL lithium myristate to the non-irrigated eye of two rabbits produced scattered or diffuse corneal opacity, iridial inflamation and moderate conjunctival irritation. Both treated eyes appeared normal at the 14 day observation.

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study, available as an unpublished report.

Justification for type of information:

See IUCLID section 13 for read across justification

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

- Selection of animals: Immediately prior to test initiation, both eyes of the provisionally selected test rabbits were examined and any animals showing evidence of ocular irritation or defect were rejected
- Age at test initiation: 12 to 20 weeks
- Acclimatisation period: At least 5 days
- Housing: Individually in suspended cages
- Feeding: Free access to mains drinking water and commercial food
- Temperature: 17 to 23°C
- Relative humidity: 30 to 70 %
- Air flow: At least fifteen changes per hour
- Photoperiod: Twelve hours continuous light (06:00 to 18:00) and twelve hours darkness

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

- Volume: 0.1 mL of lithium palmitate, equivalent to approximately 66 mg, was applied to the conjunctival sac of the right eye and the upper and lower eyelids were held together for about one second immediately after treatment

Duration of treatment / exposure:

- Duration of exposure: The rabbits' eyes were not washed

Observation period (in vivo):

- Observations of eyes: Assessment of ocular damage/irritation was made approximately 1 hour and 24, 48 and 72 hours following treatment
- Observations of reversibility: An observation was made on Day 7 to assess the reversibility of the ocular effects

Number of animals or in vitro replicates:

- Number of animals: Initially, a single rabbit was treated and after consideration of the ocular response, a second animal was treated

Details on study design:

- Control: The left eye remained untreated and was used for control purposes
- Observations of rabbits: Any other ocular effects and any clinical signs of toxicity were also noted and individual bodyweights were recorded on the day of dosing and at the end of the observation period
- Assessment method: Occular irritation potential results were interpreted according to the Globally Harmonized System of Classification and Labelling of Chemicals

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

iris score

Remarks:

mean

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.3

Max. score:

1

Reversibility:

fully reversible

Remarks:

within 48 h

Irritation parameter:

iris score

Remarks:

mean

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

conjunctivae score

Remarks:

mean

Basis:

animal #1

Time point:

24/48/72 h

Score:

1.7

Max. score:

2

Reversibility:

fully reversible

Remarks:

within 7 days

Irritation parameter:

conjunctivae score

Remarks:

mean

Basis:

animal #2

Time point:

24/48/72 h

Score:

1.3

Max. score:

2

Reversibility:

fully reversible

Remarks:

within 7 days

Irritation parameter:

chemosis score

Remarks:

mean

Basis:

animal #1

Time point:

24/48/72 h

Score:

1.3

Max. score:

2

Reversibility:

fully reversible

Remarks:

within 7 days

Irritation parameter:

chemosis score

Remarks:

mean

Basis:

animal #2

Time point:

24/48/72 h

Score:

1.3

Max. score:

2

Reversibility:

fully reversible

Remarks:

within 7 days

Irritant / corrosive response data:

- Corneal effects: None were noted during the study
- Iridial effects: Inflammation was noted in both treated eyes one hour after treatment and in one treated eye at the 24 Hour observation
- Conjunctival effects: Moderate irritation in both treated eyes at 1 and 24 hours after treatment, with minimal irritation in both treated eyes at 48 hours and in 1 treated eye at 72 hours
- Reversibility: Both treated eyes appeared normal at 7 days
- Conclusion: Lithium palmitate produced a maximum group mean score of 17.0 and was classified as a moderate irritant (Class 5 on a 1 to 8 scale) to the rabbit eye according to a modified Kay and Calandra classification system. Lithium palmitate does not meet the criteria for classification according to the Globally Harmonised System of Classification and Labelling of Chemicals or Regulation (EC) No 1272/2008, relating to the Classification, Labelling and Packaging of Dangerous Substances.

Other effects:

- Body weight: Both animals showed expected gain in bodyweight during the study

Individual scores and individual total scores for occular irritation

Rabbit Number and Sex	72629Male					72644Male
	IPR = 0					IPR = 0
Time After Treatment	1 Hour	24 Hours	48 Hours	72 Hours	7 Days	1 Hour	24 Hours	48 Hours	72 Hours	7 Days
CORNEA
E = Degree of Opacity	0	0	0	0	0	0	0	0	0	0
F = Area of Cornea Involved	0	0	0	0	0	0	0	0	0	0
Score (E x F) x 5	0	0	0	0	0	0	0	0	0	0
IRIS
D	1	1	0	0	0	1	0	0	0	0
Score (D x 5)	5	5	0	0	0	5	0	0	0	0
CONJUNCTIVAE
A = Redness	2	2	2	1	0	2	2	1	1	0
B = Chemosis	2	2	1	1	0	2	2	1	1	0
C = Discharge	2	1	0	0	0	2	1	0	0	0
Score (A + B + C) x 2	12	10	6	4	0	12	10	4	4	0
Total Score	17	15	6	4	0	17	10	4	4	0

IPR = Initial pain reaction

Individual total scores and group mean scores for occular irritation

Rabbit Number and Sex	Individual Total Scores At:
	1 Hour	24 Hours	48 Hours	72 Hours	7 Days
72629Male	17	15	6	4	0
72644Male	17	10	4	4	0
Group Total	34	25	10	8	0
Group Mean Score	17.0	12.5	5.0	4.0	0.0

Interpretation of results:

not irritating

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Lithium palmitate does not meet the criteria for classification according to the Globally Harmonised System of Classification and Labelling of Chemicals or Regulation (EC) No 1272/2008, relating to the Classification, Labelling and Packaging of Dangerous Substances.

Executive summary:

The eye irritation of lithium palmitate was assessed in a GLP-compliant, in vivo eye irritation study following OECD guideline 405 (Harlan 2013). A single treatment of lithium palmitate was applied to the non-irrigated eye of two rabbits and observations made at 1, 24, 48 and 72 hours and 7 days for effects on conjunctivae, iris and cornea and for reversibility of effects. No irritation classifiable under CLP/GHS was observed. The study is considered relevant and reliable for use for this endpoint.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The substances in the category are considered to be similar on the basis that they have common structures of a lithium ion varying only by the length of the fatty acid chain and the presence of unsaturated and/or hydroxyl functional groups. REACH Annex V, Entry 9, groups fatty acids and their potassium, sodium, calcium and magnesium salts, including C6 to C24, predominantly even-numbered, unbranched, saturated or unsaturated aliphatic monocarboxylic acids. Provided that they are obtained from natural sources and are not chemically modified, the substances included in REACH Annex V, Entry 9 are exempt from registration, unless they are classified as dangerous (except for flammability, skin irritation or eye irritation) or they meet the criteria for PBT/vPvB substances. The fatty acid components of the category members are therefore not expected to be hazardous. As all category members are lithium salts, any toxicity is expected to be driven by the lithium ion. Due to the close structural similarity and the narrow range of carbon chain numbers covered in this category, irritation potential is expected to be similar or show a predictable trend across the category.

Although fatty acids C18 (unsaturated) lithium salts is not in the list of substances being registered, this substance falls within the definition of the lithium salts of fatty acids C14-C22 category (see Appendix 1 – Category Justification Document) by virtue of its chemical structure and therefore read across from data on fatty acids C18 (unsaturated) lithium salts to other members of the category is considered to be justified (see below).

Published reviews consider that the irritant/corrosivity properties of fatty acids are chain length dependent, where the lower carbon chain lengths, < C9 are corrosive, C10 – C12 are irritant, and chain lengths from C14 are not irritating (HERA 2002, referencing Briggs et al, 1976 and CIR, 1987).

Key in vitro skin irritation studies on lithium myristate (C14) and Fatty acids C18 (unsaturated) lithium salts gave negative results. Since under REACH, in vitro studies are sufficient for compliance with Annexes VII and VIII, no key in vivo study(ies) has been conducted. A number of in vivo supporting studies in rabbits for skin irritation using greases formulated with lithium 12-hydroxystearate have been conducted. However, since these were performed several decades previously on formulated greases containing other (unknown) performance additives, the results from the in vitro skin irritation tests on isolated C14 and C18 fatty acid lithium salts are considered to be more relevant and indicative of no classification for this endpoint.

Lithium palmitate (C16), and Fatty acids C18 (unsaturated) lithium salts were subjected to in vitro eye irritation studies using the isolated rabbit eye or reconstituted human corneal epithelium models, and in vivo eye irritation studies in rabbits according to OECD 405 (key studies). For both substances, no classifiable irritation was observed. Several supporting studies where grease containing approximately 5 to 13% lithium 12-hydroxystearate was tested in rabbit eyes are reported, and where the test materials were found to be ‘not irritating’.

One reliable study (Klimisch 1) is referenced in the API Robust Summary document (2008) where lithium complex grease (containing 13.1% lithium 12-hydroxystearate and 2.6% dilithium azelate) was applied to the right eye of six rabbits. This was reported as non-irritant in the API hazard summary. The Cosmetic Ingredient Review Panel (CIR 1982) concludes that certain metal stearates (Mg, Na, Zn) were non-irritant to rabbit eye. No quality review of the data was reported and the data were either unpublished proprietary studies or from literature publications before 1960.

Lithium myristate (C14) was also tested in an OECD 405 rabbit eye irritation study. The results from this study showed ocular irritation, reversible within the 14-day observation period. Since both C16 and C18 fatty acid lithium salts gave negative results in the ocular irritation tests, the positive irritant response from lithium myristate (C14) was further reviewed. The initial substance for testing was prepared by reacting lithium hydroxide with myristic acid and washing the reaction product with isopropyl alcohol. Following substance analysis, the presence of small concentrations of residual lithium hydroxide (a strong ocular irritant) could not be excluded, and the aqueous pH (10% preparation) taken before and after the rabbit eye irritation study showed values of 10.1 drifting to 11.1 after 20 minutes. A new sample of lithium myristate was prepared, taking care to remove residual lithium hydroxide using water to wash the final product. The pH of a 10% preparation of this sample was ca 9.5 (and pH ca 8 from a sample moistened with water). Because of the modification of the synthesis, elemental analysis, and the consequent lower pH values (indicating little or no residual lithium hydroxide), it was considered appropriate to subject this sample to repeat in vitro and in vivo eye irritation studies. However, the results obtained were very similar to those from the first sample, and consequently lithium myristate is considered to be classified as an ocular irritant.

The irritant/corrosivity properties of fatty acids are chain length dependent, where the lower carbon chain length < C9 are corrosive, C10 – C12 are irritant and C14 and above are non-irritant. No ocular irritation was observed in the studies with C16 and C18 lithium salts. It is therefore concluded that the positive eye irritation results obtained with lithium myristate (C14) represents a worst case and are not indicative of a category response for the longer chain length substances. The positive results are not read across to the other category members which are considered not to be eye irritants. 

As this UVCB contains less than 3% of C12-C14 fatty acid lithium salts, and all other constituents have a chain length of C16 and above, so are considered to be non-irritant, the overall UVCB is not classified according to the EU CLP mixture toxicity rules.

Justification for selection of skin irritation / corrosion endpoint: This substance is representative of the lithium salts of C14 - C22 fatty acids and can be read across to other category members.

Justification for selection of eye irritation endpoint: Literature indicates that the irritant/corrosivity properties of free fatty acids are chain length dependent, with the lower carbon chain length < C9 being corrosive, C10 – C12 being irritant and C14 and above being non-irritant. This is supported by the experimental data where no ocular irritation was observed in the studies with C16 and C18 lithium salts though positive eye irritation results were obtained with lithium myristate (C14). As this UVCB contains less than 3% of C12-C14 fatty acid lithium salts, and all other constituents have a chain length of C16 and above, so are considered to be non-irritant, the overall UVCB is not classified according to the EU CLP mixture toxicity rules.

 

References

API (American Petroleum Institute) (2008) Robust Summary of Information on Grease Thickeners (Creation date: October 11, 2003. Printing date: February 20, 2009. Last update: October 20, 2008. Document date: January 11, 2005)

Briggs GB, Doyle RL, Young JA (1976) Safety studies on a series of fatty acids. American Industrial Hygiene Association Journal, vol. 37, pp. 251-252

CIR (Cosmetics Ingredients Review) (1982). Final report of the safety assessment of lithium stearate, aluminum distearate, aluminum stearate, aluminum tristearate, ammonium stearate, calcium stearate, magnesium stearate, potassium stearate, sodium stearate and zinc stearate. Journal of the American college of toxicologists, vol. 1, issue 12, pp. 143-177.

CIR (Cosmetics Ingredients Review) (1987) Final report on the safety assessment of oleic acid, lauric acid, palmitic acid, myristic acid and stearic acid. Journal of American Toxicologists, vol. 6, issue 3, pp. 321-401

HERA (Human Health and Environmental Risk Assessment on ingredients of European household cleaning products) (2002) Fatty Acid Salts (Soap) Environmental and Human Health Risk Assessment

Justification for classification or non-classification

Skin irritation results: All studies were negative.

Skin irritation classification: Not classified.

 

Eye irritation results: The irritant/corrosivity properties of free fatty acids are chain length dependent, where the lower carbon chain length < C9 are corrosive, C10 – C12 are irritant and C14 and above are non-irritant. Experimental data show lithium myristate, representative of C14 fatty acid lithium salts, is classified as eye irritant category 2 and C16 - C22 fatty acid lithium salts are not classified (studies were negative). It is therefore concluded that the positive eye irritation results obtained with lithium myristate (C14) represents a worst case and are not indicative of a category response for the longer chain length substances. The positive results are not read across to the other category members which are considered not to be eye irritants. 

Eye irritation classification: As this UVCB contains less than 3% of C12-C14 fatty acid lithium salts, the overall UVCB is not classified according to the EU CLP mixture toxicity rules.