Registration Dossier

Diss Factsheets

Administrative data

Description of key information

Skin irritation / corrosion:
Sodium sulfate:  not irritating, in vivo (OECD Guideline 404) 
Calcium sulfate, dihydrate: not irritating, in vivo (OECD Guideline 404)
Potassium sulfate: not irritating, in vitro (EU guideline B46 and draft OECD guidelines)
Eye irritation:
Sodium sulfate:  not irritating, in vivo (OECD Guideline 405) 
Potassium sulfate: not irritating, in vivo (OECD Guidelins 405)

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/ corrosion:

For skin irritation, data are available for each individual salts present in the Potassic extracts. In an in vitro test with human skin according to EU guideline B46 and draft OECD guidelines, potassium sulfate (incl. 15% KHSO4) did not induce irritation. In vivo tests according to OECD guideline 404 are available for calcium sulfate, dihydrate and sodium sulfate. These in vivo tests performed with New Zealand rabbits did not induce skin irritation either with calcium sulfate, dihydrate or sodium sulfate. Therefore, the available data do not support classification.

Eye irritation:

During discussion with the potassium sulfate consortium (FARM) as part of preparations for submitting a joint REACH registration dossier for potassic extracts, the possibility of classification for eye irritation due to the present of potassium hydrogen sulfate was raised. Potassium hydrogen sulfate has a harmonised classification under 67/548/EEC Annex 1 and EC 1272/2008 Annex VI and is classified due to its acidity and consequent irritant behaviour particularly to eyes. Direct analysis of hydrogen sulfate anions in the presence of sulfate anions is not feasible, therefore the manufacturing methods used to produce potassic extracts have been reviewed to determine whether there is any likelihood of this substance being included with potassic extracts. The process and isolation conditions for the formation of potassic extracts have been reviewed. The following conclusions have been reached:

- Under the complex fermentation conditions at pH 5-6, the proportion of hydrogen sulfate anion compared with sulfate anion is of the order of 0.1%.

- The process of crystallisation allows the purification and concentration of the crystallised species.

- The isolated product has been confirmed by independent analysis to contain sulfate. The pH of the isolated product lies in the range 5-8. At pH 6 (yeast production) the proportion of hydrogen sulfate anion compared with sulfate anion is of the order of 0.01 %. At pH 5 (citric acid production) the production of hydrogen sulfate anion compared with sulfate anion is of the order of 0.1 %.

- The concentration of potassium (or sodium) hydrogen sulfate salts in potassic extracts does not reach the threshold limit to require the classification of the substance under CLP.

Based on the above information, it has been judged relevant to use results from a study testing potassium sulfate (99 % pure) instead of potassium sulfate ( incl. 15 % KHSO4) to assess the eye irritant potential of potassic extracts.

In the eye irritation study performed according to OECD 405, potassium sulfate (99% pure) is not irritating in rabbits. Although some irritation was observed in the first 24 hours, this was in most animals reversible within 48 hours. Two animals showed some redness (score 1) up to 7 days after exposure, but reversible within 14 days. Determination of the irritant/ corrosive effects of sodium sulfate on eye was conducted in accordance with OECD Guideline 405. One hour post-instillation conjunctival redness [grade 1 (1 rabbit); 2 (2 rabbits)] and discharge [grade 3 (3 rabbits)] were observed. The mean scores for the 24, 48 and 72 hour readings for corneal opacity, iris, chemosis and discharge were 0 and for conjunctival redness were 1. All lesions had resolved by day 7.

It was considered in a read-across approach that the structurally similar calcium sulfate substance would also not induce irritating effect. Therefore, the available data do not support classification.

Justification for classification or non-classification

With regard to the non irritating effect of sodium, calcium and potassium sulfate potassic extracts do not have to be classified according to Directive 67/548/EC nor according to the CLP Regulation.