Reaction products of phosphoric acid, rock phosphate and humic acids, potassium salts

Endpoint summary

Description of key information

Read-across data of the components of the submission substance indicate that it is not irritating to skin, but causes irreversible effects to the 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:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Read-across data of the components of the submission substance or similar substances is available for skin irritation:

Monoammoniumphosphate:

The skin irritation potential of the test substance was tested in 6 rabbits exposed to 0.5 g test item in water (80%) for 24 h. 3/6 animals had an erythema score of 0 at the 24-h-reading and the other 3/6 animals had an erythema score of 1 at the 24-h-reading. These effects were fully reversible as 6/6 animals showed an erythema score of 0 at the 72-h-reading and at the 9-d-reading. The edema score was zero in all animals at any observation time point (24 h, 72 h, 9 d). Therefore, the test item is not irritating to skin.

Calcium superphosphate:

In a study with calcium superphosphate, the test substance proved to be not irritating to skin when tested in rabbits exposed to doses of 20 or 300 mg/kg for 24 h.

Humic acid potassium salt:

No irritating effects on skin were detected in a guideline study (EU B.4) with humic acid, potassium salt: The test substance was tested for acute dermal irritation in rabbits (New Zealand Albino breed).Test was performed according to Method B.4 - Acute Toxicity: Dermal Irritation/Corrosion, Directive 2004/73/EC, published in O.J. L 152, 2004. Three rabbits were exposed to of test substance, applied onto clipped skin for 4 hours using a semi-occlusive dressing. Skin reactions were evaluated after patch removal and observations were made 1, 24, 48 and 72 hours after exposure. No skin irritation was caused by 4-hour exposure. No other signs of intoxication were observed.

Calcium sulfate

Calcium sulfate is not irritating to skin under the conditions of an OECD TG 404 study. The substance was applied to the skin of 3 New Zealand white rabbits for 4 hours under semi-occlusvie conditions. Two animals showed slight erythema after 24 hours, which were completely reversible within 48 hours. Based on the results of this study calcium sulfate is not irritating to rabbit skin.

Read-across data of the components or similar substances is available also for eye irritation:

Single superphosphate:

Eye irritation of the test substance was tested in rabbits according to OECD TG 405 / EU B.5. One of three animals had conjunctival score of 1 (reversible) and 2/3 animals had conjunctival score of 3, irreversible within 21 days. The cornea score was zero for all animals, the iris score was zero in 1/3 animal and 0.3 in 2/3 animals (reversible) and the chemosis score was 1 in 1/3 animals and 1.3 in 2/3 animals (reversible). No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred. Therefore, the test substance is rated to have irreversible effects to the eyes.

Supporting studies on phosphates:

Single superphosphate:

Single superphosphate was tested in the BCOP (bovine cornea opacity and permeability assay). The positive and negative controls were within the historical control data. The mean in vitro irritancy score was 47 after 240 minutes of treatment with Single super phosphate (SSP). Although the corneas were turbid after the 240 minutes of treatment with Single super phosphate (SSP), the mean in vitro irritancy score (IVIS) for Single super phosphate (SSP) was below 55.1 after 240 minutes treatment. A substance producing an IVIS equal to or higher than 55.1 is defined as corrosive or severely irritating. Reaction mass of calcium bis(dihydrogenorthophosphate) and calcium hydrogenorthophosphate: Severe eye reactions were noted in a OECD 405 study at day 7 which led to the animal being euthanized for humane reasons. In accordance with Regulation (EC) No. 1272/2008 the reaction mass of calcium bis(dihydrogenorthophosphate) and calcium hydrogenorthophosphate therefore is considered to be severely irritating to eyes.

Humic acid potassium salt:

The test substance was tested for eye irritation/corrosion using albino rabbits (New Zealand Albino breed). The test was performed according to the EU Method B.5. The test was performed initially using one animal. Because neither a corrosive nor a severe irritant effect was observed in initial test, the negative response was confirmed using two additional animals. The following changes were observed: At 1 hour after application in all animals: conjunctivae - some blood vessels hyperaemic (injected) or diffuse, crimson colour, individual vessels not easily discernible, in one animal chemosis: some swelling above normal. At 24 hours after application changes were observedin two animals: conjunctivae - some blood vessels hyperaemic (injected). At 48, 72 hours after application no other signs of eye irritation were observed. No clinical signs of systemic intoxication were detected. Examination of eye irritation after single application demonstrated that the test substance is not irritating to rabbit eyes.

Calcium sulfate:

The test substance was tested for eye irritation in an OECD 405 study with 3 New Zealand white rabbits. Slight effects on cornea, conjunctivae and regarding chemosis were observed (highest individual score 0.33 for 24 to 72 h), which were reversible within 72 hours. Slight hyperemia of conjunctiva was still visible in one animal at 72 hours, but from the (non-)severeness of the effect it can be concluded that this effect was reversible as well. Based on the results from this study the substance is considered to be not irritating to the rabbit eye.

The data summarised above indicate that the submission substance is not irritating to skin, but causes irreversible effects to the eyes.

No information on respiratory irritation is available.

Effects on eye irritation: highly irritating

Justification for classification or non-classification

Due to the findings explained above, the submission substance is not classified for skin irritation according to Regulation (EC) No. 1272/2008, but for eye irritation as Category 1: irreversible effects on the eye/serious damage to eyes.