Fatty acids, C16-18, 2-ethylhexyl esters

Endpoint summary

Description of key information

All available studies on skin and eye irritation showed no irritating potential of the category members. 
Studies on acute skin irritation were available for the following category members (CAS#): 10233-13-3, 110-27-0, 142-91-6, 544-35-4, 26399-02-0, 135800-37-2 (animal and human data), 29806-73-3, 123-95-5 and 163961-32-8.
Studies on acute eye irritation were available for the following category members (CAS#): 110-27-0, 142-91-6, 544-35-4, 91031-48-0, 29806-73-3, 123-95-5 and 163961-32-8.

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)

Additional information

Ethyl ester - Skin irritation

An acute dermal toxicity study was performed with ethyl linoleate (CAS 544-35-4) according to OECD Guideline 402 (see IUCLID section 7.2.3, Otterdijk, 2010). 5 male and 5 female Wistar rats were exposed to approx. 0.6 mL (2.27 mL/kg bodyweight equivalent to 2000 mg/kg bw) undiluted liquid test substance for 24 hours under occlusive conditions. No signs of skin irritation were observed at the application sites (back skin). The test conditions were more critical than those required for a skin irritation study according to OECD Guideline 404, but no signs of skin irritation were observed within the observation period of 15 days.

Isopropyl ester - Skin irritation 

A primary dermal irritation study was performed with isopropyl laurate (CAS# 10233 -13 -3) according to OECD Guideline 404 (Dufour, 1991). The shaved skin of three rabbits was exposed to 0.5 mL unchanged test material for 4 hours under occlusive conditions. The rabbits were observed for 7 days. Skin reactions were assessed according to Directive 67/548/CEE approx. 1, 24, 48 and 72 hours as well as 7 days after removal of the test substance.

The exposure period of 4 hours caused only slight oedema and erythema in one animal. The other two animals were free of any skin irritation. All treated skin sites appeared normal at the 72 hour observation.

 

In a primary dermal irritation study, the skin irritation/corrosion potential of isopropyl myristate (CAS# 110-27-0) was tested according to OECD Guideline 404 (Mulder, 1986) in male and female rabbits. The shaved flank skin of three New Zealand White rabbits was exposed to 0.5 mL unchanged test material for 4 hours under semi-occlusive conditions. The rabbits were observed for 7 days. Skin reactions were assessed using the Draize scheme approx. 1, 24, 48 and 72 hours as well as 7 days after removal of the test substance.

The exposure period of 4 hours caused only very slight oedema and erythema in male rabbits. In female rabbits one out of 3 tested animals showed a well-defined erythema and all three female rabbits showed very slight oedema. All treated skin sites appeared normal at the 7 day observation.

 

Isopropyl palmitate (CAS# 142-91-6) was tested for its skin irritation potential according to OECD Guideline 404 (Mulder, 1986). The shaved skin of three New Zealand White rabbits was exposed to 0.5 mL unchanged test substance for 4 hours under semi-occlusive conditions. The observation period was 14 days. Slight to well-defined erythema and very slight oedema occurred at readings up to 7 days after application. All changes were fully reversible within 14 days.

 

Butyl ester - Skin irritation

Butyl stearate (CAS# 123-95-5) was tested in a primary dermal irritation study in Albino rabbits (Wallace, 1976). The shaved skin of 6 animals was exposed to 0.5 mL of the unchanged test substance for 24 hours under occlusive conditions. Treated skin sites were examined using the Draize scoring system 24 and 72 hours after application. Slight erythema was observed in two animals, which was fully reversible within 72 hours after application. No oedema occurred. Based on the study results, butyl stearate exerted no skin irritating potential.

 

Fatty acids, C16-18 and C18-unsatd., branched and linear, Bu esters (CAS# 163961-32-8) was tested in a acute dermal irritation study in rabbits according to OECD Guideline 404 (Sanders, 2002). The shaved skin of three New Zealand White rabbits was exposed to 0.5 mL of the test substance for 4 hours under semi-occlusive conditions. 24, 48 and 72 hours after patch removal the test sites were examined for evidence of primary irritation and scored according to Draize. Slight erythema and oedema occurred in all treated skin sites, which were all fully reversible within 48 or 72 hours. Based on the study results, the test substance showed no skin irritating potential.

 

Ethylhexyl ester - Skin irritation

The skin irritation/corrosion potential of 2-ethylhexyl oleate (CAS# 26399-02-0) was tested in a primary dermal irritation study according to OECD Guideline 404 (Dufour, 1991). The skin of three New Zealand White rabbits was exposed to 0.5 mL unchanged test material for 4 hours under occlusive conditions. The rabbits were observed for 72 hours. Skin reactions were assessed using the Draize scheme approx. 1, 24, 48 and 72 hours after removal of the test substance. The exposure period of 4 hours caused only very slight oedema and erythema in one rabbit. All treated skin sites appeared normal at the 48 hour observation.

 

Another acute skin irritation study was performed with Fatty acids, C8-16, 2-ethylhexyl esters (CAS# 135800-37-2) according to OECD Guideline 404 (Steiling, 1990). The shaved skin of four adult Kleinrussen rabbits was exposed to 0.5 mL test substance for 4 hours under occlusive conditions. The animals were observed for 7 days. Skin examinations according to Draize revealed only slight erythema in four animals which was fully reversible within 7 days and slight edema in one animal which was fully reversible in 48 hours. Based on these study results, Fatty acids, C8-16, 2-ethylhexyl esters had no skin irritating potential.

 

The same substance, Fatty acids, C8-16, 2-ethylhexyl esters (CAS# 135800-37-2) was tested in an occlusive patch test with human volunteers (Krächter, 1990). The test substances was applied at concentrations of 25%, 50% and 100% to the skin of 20 healthy volunteers under occlusive conditions for 24 h. Texapon N25 (1%), SDS (0.5%), Aqua dest. and Paraffin perliquid were used as controls. The volunteers were subsequently investigated for skin irritation for up to 72 h after exposition.

 

The test substance caused no effects at concentrations of 25% and 50%. The undiluted (100%) substance mainly resulted in light and transient erythema. Only one well-defined erythema and 3 cases of edema were detected. The positive controls resulted in slight to strong erythema and slight edema formation (SDS and Texapon) in 6 and 17 volunteers, respectively, supporting the sensitivity and reliability of the test method. The test substance was considered to possess very good skin compatibility at 25% and 50% dilutions and good skin compatibility as undiluted substance.

 

An acute dermal irritation test was performed with 2-ethylhexyl palmitate (CAS# 29806-73-3) according to OECD Guideline 404. The shaved skin of three New Zealand White rabbits was exposed to 0.5 mL of the unchanged test substance for 4 hours under semi-occlusive conditions. The treated skin sites were examined according to Draize scoring system 24, 48 and 72 hours after application.

Only very slight erythema and oedema occurred, which were fully reversible within 72 hours. Based on the study results 2-ethylhexyl palmitate exerted no skin irritation potential.

 

Ethyl ester - Eye irritation

An acute eye irritation study was performed with ethyl linoleate (CAS# 544-35-4) in male New Zealand White rabbits (van Otterdijk, 2010). 0.1 mL of the unchanged test substance was instilled into one eye of each of three rabbits. Observations were made 1, 24, 48 and 72 hours after instillation. No irritation of the treated eyes was observed 24, 48 and 72 hours after instillation in none of the treated animals.

 

Isopropyl ester - Eye irritation:

A primary eye irritation study was conducted with isopropyl myristate (CAS# 110-27-0) equivalent to EU Method B.5 with 3 New Zealand White rabbits (Palanker, 1977). One eye of the rabbits was exposed to 0.1 mL test substance for 24 h and subsequently scored for eye reactions. The observation period was 7 days. The readings revealed no indications for an eye irritating potential of isopropyl myristate.

 

Isopropyl palmitate (CAS# 142-91-6) was tested for its acute eye irritation potential in a study performed equivalent to OECD Guideline 405 (Prince, 1971). 0.1 mL of the unchanged test substance was instilled to the eye of 6 rabbits. 1, 24, 48 and 72 hours later treated eyes were examined for ocular lesions according to Draize. After a single instillation isopropyl palmitate caused mild irritations to rabbit eyes that were fully reversible within 72 hours.

 

Butyl ester - Eye irritation

A primary eye irritation study was performed with butyl stearate (CAS# 123-95-5). 0.1 mL of the unchanged test substance was instilled to the eye of six Albino rabbits (Wallace, 1976). Examination of the treated eyes 24, 48 and 72 hours after instillation revealed only slight conjunctival irritating effects, which were fully reversible within 48 or 72 hours. Based on the study results, butyl stearate had no eye irritation potential.

 

Fatty acids, C16-18 and C18-unsatd., branched and linear, Bu esters (CAS# 163961-32-8) was tested in a acute eye irritation study according to OECD Guideline 405 (Sanders, 2002). 0.1 mL of the unchanged liquid test substance was instilled to the eye of three New Zealand White rabbits. Examination of treated eyes 1, 24, 48 and 72 hours after instillation according to Draize revealed only slight conjunctival irritation, which was fully reversible within 48 hours.

 

Ethylhexyl ester - Eye irritation

Fatty acids, C16-18, 2-ethylhexyl esters (CAS# 91031-48-0) was examined for its eye irritation potential in a study performed equivalent to OECD Guideline 405 (Potokar, 1978). 0.05 mL undiluted test substance was instilled to the right eye of 2rabbits. 2, 6 and 24 hours after instillation examination of the treated eyes revealed no ocular lesions. Thus, based on the study results, the test substance showed no eye irritating potential.

 

2-ethylhexyl palmitate (CAS# 29806-73-3) was tested in a acute eye irritation test according to OECD Guideline 405 (Guest, 1990). 0.1 mL of the unchanged test substance was instilled to the right eye of three New Zealand White rabbits. The untreated left eye served as control. Examination of the treated eyes 24, 48 and 72 hours after instillation revealed no ocular changes. Based on the study results, 2-ethylhexyl palmitate had no eye irritation potential.

Justification for classification or non-classification

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for irritation, no classification is required.