Fatty acids, dehydrated castor-oil

Endpoint summary

Description of key information

Skin
in vitro data:
Human skin model (OECD 439; EPISKIN-SM): not irritating (Verbaan, 2012)
 
Eye
Animal data: 
Eye irritation (rabbit, 0.1mL, reading: 24, 48 and 72 h): not irritating; CAS# 112-80-1, C18:1 (USFHSA, 1974)
Eye irritation (OECD 405): not irritating; CAS# 112-86-7, C22:1 (Sterzel and Pittermann, 1992)

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin

The skin irritation potential of fatty acids, dehydrated castor-oil was determined in vitro on a human three dimensional epidermal model (EPISKIN Small Model^TM) according to OECD Guideline 439 (Verbaan, 2012). The undiluted test substance (25 µL) was applied topically for 15 minutes on the skin tissues. Phosphate buffered saline (PBS) and 5% (aq) SDS served as negative and positive control, respectively. The test was performed in triplicates for the treatment and control groups. After exposure and a 42 h post-incubation period, the cytotoxic (irritancy) effect was determined by measuring photometrically the enzymatic conversion of MTT into a blue formazan salt. The positive control had a mean cell viability of 5% and met the acceptability criteria. The absolute mean OD570 of the negative control tissues were within the laboratory historical control data range. The standard deviation value of the percentage viability of three tissues treated identically was less than 12%, indicating that the test system functioned properly. The relative mean tissue viability obtained after 15 minutes treatment with fatty acids, dehydrated castor-oil compared to the negative control tissues was 106%. Since the mean relative tissue viability for fatty acids, dehydrated castor-oil was above 50%, the substance is considered to be non-irritant in the Human Skin Model Test.

Eye

No data on eye irritation are available for fatty acids, dehydrated castor-oil. Therefore, eye irritation 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 1907/2006. In particular, the source substances structurally closest to the target substance are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Thus studies with C18:1 fatty acid (oleic acid) and C22:1 (erucic acid) are used for hazard assessment in regard to eye irritation.

 

A single application of 0.1 mL oleic acid (CAS# 112-80-1) was added to one eye of each of six albino rabbits (USFHSA, 1974). The other eye of each rabbit was left untreated and served as control. The eyes were examined at 24, 48 and 72 h after treatment, and scored for corneal opacity, iris lesions, conjunctival redness, chemosis, and discharge. The test material produced mild conjunctival redness (score of 1) and chemosis (score of 1) in one animal at the 24 h-reading and these symptoms were not reduced by the end of the observation period at 72 h. Discharge (score of 1) was also observed in this animal at the 48 and 72 h reading time points. Minor conjunctival redness (score of 1) was observed in four other animals at the 24 h-reading only. No signs of irritation were observed in one animal. The overall mean scores were 0, 0, 0.4 and 0.17 for corneal opacity, iris, conjunctival redness and chemosis, respectively. Thus, oleic acid is not regarded as eye irritant.

Briggs et al. (1976) reported mild conjunctival redness with complete clearing within 72 h for a mixture containing 75% oleic acid and 7.4% linolenic acid.

No or minimal conjunctival irritation was observed in the eyes of 6 albino rabbits treated with 0.1 mL oleic acid as commercially supplied using the Draize Method (Elder, 1987).

 

The eye irritation potential of erucic acid (CAS# 112-86-7) was determined according to OECD Guideline 405 under GLP conditions (Sterzel and Pittermann, 1992). The undiluted test substance was instilled into the right eye of each of three Himalayan rabbits, while the untreated eye of each animal served as control. The test substance was washed out 24 h after application. Mild conjunctival redness was observed in one animal at the 1-hour reading time point and disappeared completely within 24 h. No irritation effects of the two additional animals were noted at the 24, 48 and 72 h reading time points. Therefore, erucic acid is not considered as eye irritant.

 

In conclusion, oleic acid and erucic acid are not irritating to the eye based on the available animal data. By means of read-across based on similar structural (unsaturated long-chain fatty acids) and toxicological properties of fatty acids, dehydrated castor-oil, oleic acid and erucic acid, the same result is expected for fatty acids, dehydrated castor-oil. Thus, fatty acids, dehydrated castor-oil is considered to be not irritating to eyes.

References:

Briggs, G.B. et al. (1976). Safety studies on a series of fatty acids. Am Ind Hyg Assoc J. 37(4):251-253. Testing laboratory: International Bio-Research, Miamiville, Ohio, USA

Elder (1987) Final Report on the Safety Assessment of Oleic Acid, Lauric Acid, Palmitic Acid, Myristic Acid, and Stearic Acid, Journal of the American College of Toxicology, 6(3): 321-401

Justification for selection of skin irritation / corrosion endpoint:
There is only one key study available.

Justification for selection of eye irritation endpoint:
Hazard assessment is conducted by means of reas-across based on a category approach. All available studies are adequate and reliable based on the identified similarities in structure and intrinsic properties between source and target substances and overall quality assessment (refer to the endpoint discussion for further details).

Justification for classification or non-classification

The available data on skin irritation of fatty acids, dehydrated castor-oil do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.

By means of read-across based on a category approach, the available data on eye irritation does not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.