Sodium sulphate

Endpoint summary

Description of key information

Test results available for acute toxicity rat (oral and inhalation).

LC50, 4h (rat, inhalation) > 2400 mg/m3 air

LCLo, 72h (rat, inhalation) > 10 mg/m3 air

Based on the results of several acute toxicity inhalation studies it is unlikely that short-term inhalation of respirable sodium sulfate particles cause pulmonary irritation or systemic effects;

The acute dermal toxicity (rat) is waived: Annex XI adaptation- inorganic ionic substance low potential for absorption through the skin.  

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Value:

mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

2 400 mg/m³ air

Additional information

ORAL

LD50 (rat, oral) > 2000 mg/kg (test substance)

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

DERMAL

No data. Waived. Given the complete dissociation in solution, penetration through the intact skin is not to be expected.

INHALATION

LC 50, 4h (rat, inhalation) > 2.4 mg/L air (gravimetrically determined mean aerosol concentration)

LCLo, 72h (rat, inhalation) > 10 mg/m3 air

In an acute inhalation study performed at Harlan Labs (Pothmann D., 2010) the ranges of aerosol concentration, temperature, relative humidity, oxygen content and airflow rate measured during the exposure were considered to be satisfactory for a study of this type. In addition, the test item was considered to be respirable to rats. All animals survived the scheduled observation period.

Ruffled fur was recorded in all animals one hour after the end of exposure and on test day 2. From test day 3 onwards no clinical signs were observed. Slight effects on body weight were recorded during the observation period. There were no macroscopic findings during necropsy.

It was concluded that the LC₅₀ of Sodium Sulphate obtained in this study was estimated to be greater than 2.4 mg/L air (gravimetrically determined mean aerosol concentration) which was the highest technically feasible aerosol concentration.There was no indication of relevant sex-related differences in toxicity of the test item.

In an inhalation toxicity study (according to Last and Cross, J. Lab. Clin. Med. 91: 328-339 (1978)), 6 male Sprague-Dawley rats were exposure to aerosols of sodium sulfate at levels of 10 mg/m³ for 72 hours. The responses to breathing these aerosols were evaluated by measurements of glycoprotein, RNA and DNA contents of homogenates of the lungs and quantification of wet to dry weight ratios of the lung lobs. No mortality was reported. The RNA, DNA and protein levels were 99, 100 and 107, respectively (the control values were 100). The lung wet to dry ratio was 4.35 in the first experiment and 4.5 in the second experiment (control value was 4.5) (Last, 1980).

In another experiment the bronchial mucociliary clearance was measured in 5 male rabbits by brief inhalation of radiolabelled, insoluble tracer microspheres (99mTc-tagged ferric oxide). The thoracic retention was measured externally in vivo. These measurements began within 2 min. after the inhalation and were repeated after 24 hours to determine a value for residual activity. The mucociliary clearance was determined as mean residence time (MRT) of the tracer. No effect on mucociliary clearance was found (one way ANOVA, two tailed) (Schlessinger, 1984).

The intestinal effects of sulfate in drinking water (up to 1200 mg/l) on normal human subjects (10) has 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 colored 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).

Justification for classification or non-classification

Based on the test results and supporting data (rat: oral and inhalation) and on the waiver (dermal) the substance Sodium sulphate should not be classified.

Based on the absence of major significant effects, sodium sulfate does not need to be classified for acute toxicity according to EU Directive 67/548/EEC and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP).