Sodium hydrogencarbonate

Endpoint summary

Description of key information

Sodium bicarbonate was not irritating to rabbit skin and eyes in the GLP-compliant studies, performed according to OECD Guidelines 404 and 405 and EPA OTS 798.4470 and OTS 798.4500 protocols.

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 irritating properties of sodium bicarbonate have been studied in 2 GLP-compliant studies, performed according to OECD Guideline 404 and EPA Guideline OTS 798.4470. In the first study, 0.3 g of the test substance (0.5 ml bump volume) was applied to the shaved skins of 3 male rabbits for 4 hours under semi-occlusive conditions. One rabbit had a slight erythema (score 1) 1 hour after the test patch removal, which was resolved at 24 hours examination. Another had slight erythema (score 1) observed 24 hours after the test patch removal, which was resolved at 48 hours examination. In the second study, 0.5 g of the test substance, moistened with distilled water prior to application, was applied under semi-occlusive conditions to clipped skins of 3 male and 3 female rabbits. Very slight erythema and oedema were noted at 1 hour post-application (scores 0.7 and 0.2, respectively), which were fully resolved at 48 hours examination. Based on the results of these two studies, sodium bicarbonate is concluded to be not irritating to rabbit skin.

Eye irritating potential of sodium bicarbonate has been studied in two GLP-compliant studies, performed according to OECD Guideline 405 (Henkel, 1991b) and EPA Guideline EPA OTS 798.4500. In the first study, 0.05-0.07 ml (bump volume) of the test substance were instilled into the eyes of three rabbits, the untreated eyes serving as negative controls. Twenty -four hours post-instillation, the eyes were rinsed thoroughly with tepid water and the reactions were scored using the Draize system. All rabbits had a slight to moderate conjunctival erythema (scores 1-2) 1 hour after the instillation, which was resolved at 48 hours observation. Two out of three animals also exhibited mild chemosis (score 1), which was resolved at 24 hours observation. In the second study, 0.1 g of the test substance was instilled in the eyes of 9 rabbits. The treated eyes of three rabbits were irrigated with 30 ml of physiological saline approximately 20-30 seconds after installation of the test substance. The eyes of the remaining six rabbits were not irrigated. The rabbits were observed for four days. No corneal opacity was noted during the study. One washed and one unwashed eye exhibited iritis one hour after installation only. All treated eyes had conjunctivitis. The incidence and severity of irritation decreased with time. All ocular irritation cleared from the washed and unwashed eyes by days 3 and 4, respectively. Based on these results, sodium bicarbonate is considered to be non-irritating to rabbit eye.

[partly taken from OECD SIDS on sodium bicarbonate (2002), pg. 14 -15]

 

Justification for classification or non-classification

Based on the results of GLP-compliant studies on skin and eye irritation in rabbits, performed according to OECD and/or EPA guidelines, classification of sodium bicarbonate as skin and eye irritant is not warranted according to CLP Regulation (EC) No 1272/2008.