Potassium hydrogensulphate

Endpoint summary

Description of key information

Read-across conclusions for the following properties under consideration

The basis for the read-across concept for this project is the equilibrium between sulfates, hydrogensulfates, and sulfuric acid in aqueous solutions depending on pH value which is clearly described in published literature and summarised in the following equations:

H₂SO₄<-> HSO₄^-+ H⁺      HSO₄^-<-> H⁺+ SO₄^2-

As the nature of the cation should make no significant difference in this case concerning toxicity and solubility (all compounds are very soluble in water), only the chemical and biological properties of the anion are considered relevant. Based on the described equilibrium correlations, we propose unrestricted read-across between the groups of sulfates, hydrogensulfates and sulfuric acid concerning systemic toxicity.

 

The proposed read-across concept only applies to toxicological and ecotoxicological/environmental fate endpoints.

Test results are available for sodium sulfate and sulfuric acid for acute toxicity rat (oral).

Sodium sulfate:

LD50 (rat,oral) > 2000 mg/kg bw (Areclin)

LD50 (rat, oral) > 10 g/kg bw (Henkel)

Sulfuric acid:

LD50 2140 mg/kg bw

Based on the assumption described in the read-across concept, read-across from sodium sulfate and sulfuric acid to potassium hydrogensulfate is considered justified. Threfore it can be concluded that potassium hydrogensulfate has no acute-toxic propoerties.

Additional information

Read-across conclusions for the following properties under consideration

The basis for the read-across concept for this project is the equilibrium between sulfates, hydrogensulfates, and sulfuric acid in aqueous solutions depending on pH value which is clearly described in published literature and summarised in the following equations:

H₂SO₄<-> HSO₄^-+ H⁺      HSO₄^-<-> H⁺+ SO₄^2-

As the nature of the cation should make no significant difference in this case concerning toxicity and solubility (all compounds are very soluble in water), only the chemical and biological properties of the anion are considered relevant. Based on the described equilibrium correlations, we propose unrestricted read-across between the groups of sulfates, hydrogensulfates and sulfuric acid concerning systemic toxicity.

The proposed read-across concept only applies to toxicological and ecotoxicological/environmental fate endpoints.

In view of the acidic reaction to be expected upon dissociation of sodium hydrogensulfite in aqueous media, partial read-across needs to be considered to sulfuric acid, as outlined below. However, the applicability is somewhat restricted since during the gastric passage, an acidic pH (1-2) is already established under normal physiological conditions. Concerning inhalation particle size considerations render solid, commercially available sodium hydrogensulfate as practically unavailable via the inhalation route. Finally, dermal absorption and thus dermal toxicity may be considered negligible. For all other aspects, read-across to sodium sulfate is taken into account in the absence of data specifically for sodium hydrogensulfate.

Sodium hydrogensulfate:

Sodium hydrogensulfate readily dissociates in water with an acidic reaction, resulting in hydrogensulfate anions and sodium cations. The hydrogensulfate anion (pKa=1,99¹) partly dissociates further to sulfate anion and the hydrogen cation, which is responsible for the acidic reaction. Based on these dissolution characteristics, it can be concluded that the toxicity of sodium hydrogensulfate is primarily induced by the acidic reaction. The sulfate anion is not expected to contribute to a relevant extent to overall toxicity

Acute oral toxicity:

Reliable data on acute oral toxicity for sodium hydrogensulfate is not available.

Sulfuric acid:

Acute oral toxicity

The single available acute oral toxicity study (Smythet al, 1969) performed with sulfuric acid reports an LD50 value of 2140 (1540 -2990) mg/kg bw. The study is reported in summary form only but the protocol design is comparable to OECD 401. The results of this study indicate that sulfuric acid is of low acute systemic toxicity when administered by gastric intubation. However it should be noted that the route of administration used in this study eliminates the potential for local corrosive effects of the test material on the upper gastrointestinal tract (mouth, pharynx and oesophagus). Following accidental/intentional oral ingestion of sulfuric acid by humans, the local effects on the upper gastrointestinal tract are likely to dominate the clinical presentation and the potential for systemic toxicity is likely to be low. Further testing of sulfuric acid for acute oral toxicity in animals (i. e. in a guideline- and GLP-compliant study) is not proposed for acute oral toxicity and for reasons of animal welfare, due to the corrosivity of the substance.

Sodium sulfate:

ORAL

LD₅₀(rat, oral) > 2000 mg/kg bw (Areclin)

LD₅₀(rat, oral) > 10 g/kg bw (Henkel)

The intestinal effects of sulfate in drinking water (up to 1200 mg/l) on normal human subjects (10) have been investigated. The health of the subjects was determined by studying their history, physical examination, urine analysis, blood cell counts and serum chemistry. During the study stool mass, frequency and consistency in mouth to anus appearance of coloured markers were measured. No significant change in bodyweight was observed. All blood and urine test results were normal. At 1200 mg/l 8 subjects rated the taste of the water as neutral-slightly unpleasant, 1 subject as moderately unpleasant and 1 subject as very unpleasant. Significant decreases in stool consistency and appearance time were noted at 1200 mg/l, compared to the control (Heizer, 1997).

Potassium:

Potassium is an essential nutrient involved in fluid, acid and electrolyte balance and is required for normal cellular function. In rats the oral LD50 of KCl is reported to be 2.4-3.0 g/kg body weight (Von Oettingen, 1956; Boyd and Shanas, 1961).

The following information is taken into account for any hazard / risk assessment:

Test results are available for sodium sulfate and sulfuric acid for acute toxicity rat (oral and inhalation).

Sodium sulfate:

LD₅₀(rat, oral) > 2000 mg/kg bw (Areclin)

LD₅₀(rat, oral) > 10 g/kg bw (Henkel)

 

Sulfuric acid:

LD₅₀2140 mg/kg bw

Potassium (K+

Based on the assumption described in the read-across concept, read-across from sodium sulfate and sulfuric acid, sodium hydrogensulfate to potassium hydrogensulfate is considered justified. Therefore it can be concluded that potassium hydrogensulfate has no acute-toxic properties.

Justification for classification or non-classification

Based on the test results of the read-across substances sodium sulfate and sulfuric acid, potassium hydrogensulfate does not require classification for acute oral, toxicity according to EC Regulation No. 1272/2008 and subsequent regulations.