Potassium sulfate

Endpoint summary

Description of key information

With potassium sulphate a reliable acute dermal toxicity study in rats (according to OECD 402) has been performed showing an LD50 > 2000 mg/kgbw. A reliable acute oral toxicity study with rats according to OECD 425 with potassium magnesium sulphate has been performed, showing LD50>2000 mg/kg bw.  An inhalation study with ammonium sulphate investigating mucociliary clearance did not show effects in rats at 3.6 mg/m3.
Based on reliable studies on potassium magnesium sulphate and ammonium sulphate for acute oral route, the LD50 for the sulphate category is >2000 mg/kg. Based on a reliable acute inhalation study on ammonium sulphate, the LC50 for the sulphate category is >1200 mg/m3.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

1 200 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

No reliable acute oral toxicity study is available for potassium sulphate. However, several second source publications show a high oral LD50 value for potassium sulphate. This is confirmed by reliable acute oral toxicity studies performed in rats according to OECD 425 with potassium magnesium sulphate (and ammonium phosphate sulphate) (LD50 > 2000 mg/kg bw).

For acute dermal toxicity a reliable OECD 402, EC B.3, EPA and JMAFF guideline study in rats with potassium sulphate itself is available, showing an LD50>2000 mg/kg bw. No mortality, effects on body weight and gross pathology were observed. However, some effects on the skin were: Chromodacryorrhoea was noted in two males and one female on Day 1. Scales and scabs were noted in one male and one female between Day 5 and 11.

Therefore, acute toxicity studies with two possible routes of exposure are available and thus no acute inhalation study is required. In addition, the vapour pressure is assumed to be very low and for the granules and the powder of the substance, hardly any/limited number of particles are present that are inhalable (<100 micrometer) (see particle size distribution). However, mucociliary clearance was investigated with ammonium sulphate and appeared not to have been significantly affected in male rats exposed to 3.6 mg/m³ (0.4 µm) for 4 h. In addition, the acute inhalation toxicity of ammonium sulfate aerosols (average diameter 1 - 3 µm) is very low with 8-h LC50 values of greater than 900 mg/m³ for guinea pigs. Rats were exposed repeatedly for 8 h/d to 1000 - 1200 mg/m³ (average diameter 2 - 3 µm) without mortality. No specific signs of toxicity were reported from these studies.

Justification for classification or non-classification

Studies show that potassium sulphate does not have to be classified for acute toxicity according to Directive 67/548/EC and the CLP Directive.