Potassium hydrogen oxalate

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

LOAEL

150 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Additional information

Oxalates can be assimilated to oxalic acid. Two repeated dose studies were conducted, which are summarized in the following table.

Study references	Study type	Results	Remarks	Reliability
NON KEY_1977_lit_Goldman	Oral via food (2,5 and 5%), 70 days, effects on growth and reproduction	Decrease in growth rate, body weight, reproductive tissue weights	No NOAEL identified	2
NON KEY_1979_lit_Goldman	Oral via food (2,5 and 5%), 70 days, effects on thyroid function	Decreased body and thyroid weight at 2.5 and 5%, state of thyroidism at 5%	No NOAEL identified	2

Both works of Goldman, M et al. studying the sub-chronic toxicity with repeated doses in rats for 70 days are considered by the Agencies (EU: EMEA & PAN Pesticides Database-Chemicals, U.S. National Toxicology Program) as the basis of repeated dose toxicity 2000 mg / kg bw / day. The Japanese Agency (NITE, National Institute of Technology and Evaluation) provides a GLP work, OECD 407 in rats in repeated doses for 28 days, which showed no change in weight or quantity of water or food consumed, or biochemical changes were observed or in urine, no significant change in weight of organs in both sexes. But in high doses, 150 mg/kg bw and 400 mg / kg bw significant histopathological changes were observed in the gastric mucosa; that established a LOAEL of 150 mg/kg/d bw, since no lower doses were tested.

In assessing the hazard of oxalic acid, it should be kept in mind that oxalic acid is a natural substance which is present in various food substances, and in this way is consumed by the general population daily. From Gold et al (2001), the following table was derived, in which the average daily consumption of oxalic acid containing food is summarized. A total average daily consumption of 68.4 mg oxalic acid can be calculated from this table.

Food substance (average daily consumption)	Average daily oxalic acid consumption
Coffee (500 mL)	25.2 mg
Carrot (boiled, 12.1 g)	22.7 mg
Tea (60.2 mL)	6.67 mg
Chocolate (cocoa solids, 3.34 g)	3.91 mg
Tomato (88.7 g)	3.24 mg
Celery (7.95 g)	1.39 mg
Potato (54.9 g)	1.26 mg
Corn (33.8 g)	1.12 mg
Apple (32.0 g)	704 µg
(10.5 g)	651 µg
Lettuce (14.9 g)	447 µg
Broccoli (6.71 g)	268 µg
Strawberry (4.38 g)	261 µg
Cabbage (boiled, 12.9 g)	155 µg
Grapes (11 g)	138 µg
Cucumber (raw flesh, 11.8 g)	118 µg
Peach (canned, 9.58 g)	115 µg
Onions (green, cooked, 137 mg)	31.5 µg

Justification for classification or non-classification

Data do not support classification.