Phosphoric acid, mono- and di-isotridecyl esters, potassium salts

Endpoint summary

Description of key information

Based on the results of in vivo/in vitro studies, the test substance is considered to be not irritating to skin but can induce serious eye damage.

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:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation:

Study 1: A, in vitro study was conducted to determine the skin irritation potential of the test substance according to OECD Guideline 439 and EU Method B.46, in compliance with GLP. The test system used was a human skin model: "EPISKIN Small Model" (a three-dimensional human epidermis model consisting of adult human derived epidermal keratinocytes). The keratinocytes were cultured for 13 days, which resulted in a highly differentiated and stratified epidermis model. The skin was exposed to 10 mg unchanged test substance (no vehicle) for 15 min, followed by a post-incubation period of 42 h. The determination of the cytotoxic (irritancy) effect was performed after the post-incubation. Cytotoxicity was expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the treatment. The cell viability (%) was then calculated. The positive and negative controls were valid. Tests 1 and 2 gave values of 38, 43, 55% and 48, 69, and 71%, respectively, when compared to the negative control tissues. Under the study conditions, the in vitro skin irritation potential of the test substance could not be established as the results were inconclusive (Eurlings, 2016).

Study 2: An in vivo study was conducted to determine the skin irritation potential of the test substance according to OECD Guideline 404, EU Method B.4, EPA OPPTS 870.2500 and Japanese Ministry of Agriculture, Forestry and Fisheries (JMAFF), 12 Nousan, Notification No 8147, in compliance with GLP. Three male New-Zealand white rabbits were used in this experiment. Approximately 24 h before treatment, the dorsal fur was clipped with electric clippers, exposing an area of approximately 150 square centimetres (10x15 cm). Each animal was treated by dermal application of 0.5 g of the test substance for 4 h using a semi-occlusive dressing. The test substance was moistened with 0.5 mL of the vehicle and applied to the skin of one flank, using a metalline patch of 2x3 cm. The patch was mounted on Micropore tape, which was wrapped around the abdomen and secured with Coban elastic bandage. 4 h after the application, the dressing was removed and the skin cleaned of residual test substance using tap water. Skin reactions were assessed 1, 24, 48 and 72 h and 7 and 14 d after exposure. The irritation scores and a description of all other (local) effects were recorded. Adjacent areas of the untreated skin of each animal served as controls. The irritation was assessed according to the standard numerical scoring system. At each observation, the highest scores given were recorded. Mortality/viability was assessed twice daily. Toxicity was recorded at least once daily. Body weight were measured on the day of treatment (prior to application) and on the day of the final observation. No histopathology was performed. Exposure to the test substance resulted in very slight or well-defined erythema and very slight or well-defined oedema in the treated skin areas of the three rabbits, which had resolved within 7 d after exposure in one animal, within 14 d after exposure in another animal and persisted until termination in the third animal. There was no evidence of a corrosive effect on the skin. No staining of the treated skin by the test substance was observed and no test substance remnants were seen. No signs of systemic toxicity were observed in the animals during the test period and no mortality occurred. The body weight was not modified by the treatment. Under the study conditions, the test substance was considered to be not irritating to rabbit skin (van Huigevoort, 2016).

Eye irritation:

An in vitro study was conducted to determine the eye irritation potential of the test substance according to OECD guideline 473 (bovine corneal opacity and permeability (BCOP) test), in compliance with GLP. Bovine corneas were exposed to the test substance for a period of 240 minutes. Opacity and permeability were measured and an in vitro irritancy score was then established. Physiological saline and imidazole were used as negative and positive controls, respectively. The corneas treated with the test substance showed opacity values ranging from 22 to 72 and permeability values ranging from 8.021 to 9.653. The corneas were turbid after the 240 minutes of treatment. No pH effect of the test substance was observed on the rinsing medium. The in vitro irritancy scores ranged from 155 to 217 after 240 minutes of treatment. The negative and positive control values were within the expected range; hence the experiment was considered valid. Under the study conditions, the test substance induced serious eye damage through both endpoints (opacity and permeability), resulting in a mean in vitro irritancy score (IVIS) of 177 after 240 minutes of treatment (Eurlings, 2016). Based on the IVIS > 55, it was concluded that the test substance induced serious eye damage in the Bovine Corneal Opacity and Permeability test.

Justification for classification or non-classification

Skin irritation:

Based on the results of an in vivo skin irritation study, the test substance does not need to be classified according to CLP (Regulation 1272/2008/EC) criteria.

Eye irritation:

Based on the results of an in vitro eye irritation study, the test substance is considered to meet the classification of Eye Damage 1 - H318 - causes serious eye damage according to CLP (Regulation 1272/2008/EC) criteria.​