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EC number: 232-216-8 | CAS number: 7790-62-7
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
The test substance will rapidly hydrolyse to sulphuric acid and sulphate anion in biological fluids and tissues. The sulphate anion is well absorbed from the lung and intestinal tract. Absorption estimates from the lung indicate a non-saturable process with an absorption half-life of 34 minutes in rats. In human studies, the data show that sulphate is essentially fully absorbed by the oral route of exposure within 2 hours. Dietary studies indicate that 97% of the ingested sulphate is found in the urine indicating essentially complete absorption and excretion. Thus these values support 100% absorption of sulphate from the oral route of exposure. The complete elimination of sulphate from balance studies indicate low potential for bioaccumulation.
Key value for chemical safety assessment
- Bioaccumulation potential:
- low bioaccumulation potential
- Absorption rate - oral (%):
- 100
Additional information
The target substance rapidly hydrolyses in water to form sulphuric acid and potassium sulphate (K+2SO42-), the source substances. A hydrolysis study was undertaken where the reaction of the test substance was followed using laser Raman spectroscopy. The study demonstrated that at 1 M concentration of test substance, it took 22 minutes for the reaction to run to completion. At 0.1 M concentration of test substance it took less than 3 minutes for the reaction to go to completion. The reaction appeared to be relatively independent of starting pH. The effect of the starting test substance concentration of on the hydrolysis rate appears to be largely due to dissolution kinetics and mixing dynamics apparent at the higher test concentration. At a pH of 7.4, a biologically relevant pH given it’s the typical pH of blood/tissue, the hydrolysis products appeared to be entirely in the form of sulphate ions, SO42-. The hydrolysis reaction of pyrosulphate is given by the following equation:
S2O72-+ H2O -> 2HSO4- (1)
In aqueous solution, the bisulphate ion generated by this hydrolysis further transforms according to the following equilibrium equation:
2HSO4-<--> 2H++ 2SO42- (2)
This is the functional equivalent of each mole of pyrosulphate anion producing 1 mole of sulphate and 1 mole of sulphuric acid at biologically relevant pHs.
S2O72-+ H2O -> H2SO4+ SO42- (3)
Thus potassium sulphate and sulphuric acid are considered to form a group of relevant analogues to characterise the hazard profile of the test substance.
The sulphuric acid formed from hydrolysis is not expected to be absorbed or distributed throughout the body. Instead, the acid will dissociate and the anion will enter the body’s electrolyte pool and not play a specific toxicological role. The presence of the hydronium ion will have an impact on the acute toxicity effects and, depending upon the amount, will be buffered by the various carbonate, phosphate, and protein buffer systems present in the body.
Sulphate, formed from hydrolysis of the target substance, is an important macronutrient for the normal function of cells and is the fourth most abundant anion in human plasma (300 µM). Sulphate is absorbed from the intestine by an active transport system. All cells have sulphate transporter for the influx/efflux of sulphate. Sulphate is also used for detoxification of compounds to sulphate esters, which can be excreted in the urine. Sulphate is eliminated by the kidney and levels are regulated by the kidney through a reabsorption mechanism.
Multiple absorption and kinetic studies with sulphate and sulphate ions were performed in rats and humans. In rats, absorption of inorganic sulphate after oral ingestion of 0.25 to 5 mmol was investigated. After oral administration of Na235SO4, radioactive35S was measurable in plasma after 15 minutes, and its plasma concentration reached a peak after about 1.5-2 hours. The35S-radioactivity excreted in urine during the 24 hours after ingestion of Na235SO4 together with varying amounts of unlabelled Na2SO4 (0.25--5.0 mmol Na2SO4 per rat) indicated an almost complete absorption of inorganic sulphate from the gastrointestinal tract. Determination of the inorganic sulphate concentration in rat serum 2 hours after oral administration of 5.0 mmol Na2SO4 revealed a three-fold increase in serum sulphate concentration. The data suggest a rapid and almost complete absorption of inorganic sulphate after oral administration in the rat.
To investigate the absorption of 35S-sulphate ions from the rat lung in the presence of sodium ions, 0.1 ml of isotonic sucrose solution containing the salt was instilled via a tracheal cannula into anesthetized animals. After various times the lungs were removed and assayed for 35S-radioactivity. Sulphate ion absorption was found to be nonsaturable and proportional to the concentration of sulphate ion, with a t1/2 of 34.5 minutes.
Human volunteers received an i.v. dose, followed by 24-hours fluid restriction and blood and urine collection to determine radioactivity and creatinine concentration. The same volunteers received the same amount orally 2-14 days later, followed by same regimen. Plasma equilibrium was reached within 90 minutes for i.v. and 105 minutes for oral dosing. Eighty percent or greater of the 35S dose was recovered in the 24-hour urine, following either i.v. or oral administration. The calculated mean extracellular fluid space was 16.8±1.1 and 15.3±1.2 respectively, or only 9%. The test substance was absorbed completely and rapidly.
In another human study, subjects received either a single dose of 18.1 g Na2SO4 decahydrate (800 g of the anhydrous salt) or were dosed in 4 hourly increments one week later. After dosing, urine was collected in 24-hour portions over a 72 hour period. The single dose caused severe diarrhoea, but the divided dose did not. The test substance is better absorbed from the intestine when given in a divided dose than when administered in a single large dose, indicating saturation of the transport system.
Sulphate balance studies were performed on six healthy ileostomists and three normal subjects. The subjects were fed diets which varied in sulphate content from 1.6-16.6 mmol/day. Sulphate was measured in diets, faeces (ileal effluent in ileostomists), and urine. Overall there was net absorption of dietary sulphate, with the absorptive capacity of the gastrointestinal tract plateauing at 5 mmol/day and exceeding 16 mmol/day in the normal subjects. Faecal losses of sulphate were trivial in the normal subjects at all doses. Urinary excretion of sulphate in the normal subjects correlated linearly with dietary sulphate; 97% of dietary sulphate was excreted in urine. It is concluded that diet and intestinal absorption are the principal factors affecting the amounts of sulphate reaching the colon.
Based on the multiple studies in rats and humans with sulphate, the test substance is expected to be rapidly absorbed and excreted in humans.
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