Tris[(2-hydroxyethyl)ammonium] citrate

Endpoint summary

Description of key information

The substance is not irritating to skin and eyes. 

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

Skin irritation

The skin irritation potential of tris[(2 -hydroxyethyl)ammonium] citrate was studied in vitro in the GLP-compliant OECD Guideline 439, using Epiderm reconstructed skin membranes (TNO Triskelion B.V., 2011a). The EpiDerm™ skin membranes were topically exposed the test substance for 1 h. After culturing for 42 h the viability of the epidermal cells was assessed using the MTT test. The general principle for the detection of viability via the MTT test is the conversion of the yellow tetrazolium salt (MTT) to the purple coloured product formazan by mitochondrial enzymes. The formation of formazan was measured using a spectrophotometer. The results were interpreted according to the following scheme: if the mean tissue viability expressed as % of negative control was ≥ 50%, the substance was considered not irritating to skin (UN GHS No Category); if the mean tissue viability was < 50%, the substance was considered to be irritating; UN GHS Category 2. Phosphate-buffered saline (PBS) and 5% sodium dodecyl sulphate (SDS) were used as a positive and a negative controls, respectively. Three replicates were used for each substance.

The mean tissue viability was 96 ± 3% for tris[(2 -hydroxyethyl)ammonium] citrate, 100 ± 1% for PBS and 5 ± 1% for 5% SDS. Based on the results of the study, the substance is not irritating to skin.

Eye irritation

Eye irritating potency of tris[(2 -hydroxyethyl)amminoum] citrate was studied in vivo in the GLP-compliant OECD Guideline 405 study with three female New Zealand White rabbits (TNO Triskelion B.V., 2011b). The study was conducted after the non-GLP evaluation of the eye irritation in vitro using the Isolated Chicken Eye Test (OECD 438) did not reveal signs of severe irritancy. 0.1 mL of the test substance was instilled into the conjunctival cul-de-sac of the right eye of each rabbit; the untreated eyes served as negative controls. The effects were scored at 1, 24, 48, 72 hours and 7 days post-instillation. The substance caused slight redness (mean score at 24 + 48 + 72 hours 0.72 out of max. 3) and slight swelling of the conjunctivae (mean score 1 at 1 hours post-observation out of max. 4; mean score 0 at 24 + 48 + 72 hours) and moderate ocular discharge (mean score 2 out of max. 3 at 1 hour post-instillation; mean score 0 at 24 + 48 + 72 hours). At 72 hours after treatment, the eye effects had cleared completely. Based on the results of the study, the substance is not irritating to eyes.

Justification for classification or non-classification

Based on the negative results of the GLP-compliant guideline in vitro skin irritation study with the EpiDerm skin membranes and in vivo study with rabbits, classification of the substance for skin and eye irritation is not warranted in accordance with EU Directive 67/548 and EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.