Reaction mass of diisobutyl hydrogen phosphate and isobutyl dihydrogen phosphate

Endpoint summary

Description of key information

The available experimental data in animals suggest oral absorption and systemic distribution of the submitted substance since clinical signs and slight variation in blood biochemistry were reported in the acute and repeated administration oral toxicity studies. No indications on the submitted substance metabolism and excretion were obtained.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

No specific toxicocinetic studies are available on the Reaction mass of "Diisobutyl hydrogen phosphate and Isobutyl dihydrogen phosphate". A toxicokinetic assessment was done based on the physico-chemical properties of the submitted substance and based on the results of the acute and repeated administration toxicity studies by oral route.

Physico-chemical properties of the Reaction mass of "Diisobutyl hydrogen phosphate and Isobutyl dihydrogen phosphate":

- Water solubility: 27.5 g/L (at 20°C)

- Boiling point: Experimental value of boiling point at 100 kPa: test item decompose with partial boiling over the temperature range of 194 to 246 °C (467 to 519 K).

- Partition coefficient in octanol/water: - 1.67 (at 21°C)

- Vapour pressure: 3.7 x 10*-4 (at 25°C)

- Density: 1.11 (at 20°C)

Absorption:

Inhalation:

No data were available for this route of exposure. However, the submitted substance is a liquid with a low volatility, as evidenced by the very low vapour pressure. Therefore it can be considered that the absorption by the inhalation route is limited.

Oral:

No mortality was observed after the single oral administration of the Reaction mass of "Diisobutyl hydrogen phosphate and Isobutyl dihydrogen phosphate" to rats at the dose of 2000 mg/kg bw. Clinical signs were noted in animals treated at the 2000 mg/kg bw dose level: dyspnea, piloerection, hunched posture.

In the repeated administration subacute study, ptyalism was observed at the 400 and 1000vmg/kg bw doses. Bilirubin and protein levels were slightly decreased at 1000 mg/kg. Evidences of local irritation effects were seen on the digestive tract.

Observations made on the oral acute and repeated adminstration toxicity studies support an absorption of the submitted substance by the oral route even if some of these effects may be related to the corrosive properties of the substance.

Dermal route:

Since the submitted substance is classified as corrosive, no in vivo study was performed by the dermal route. However, it can be assumed that the corrosive properties of the submitted substance would enhance the dermal penetration of the substance (see Guidance on information requirements and chemical safety assessment: Chapter R.7c: Endpoint specific guidance). The absorption by the dermal route is therefore possible.

Distribution:

The clinical signs observed in the acute and repeated administration oral toxicity studies suggest a systemic distribution of the submitted substance. The high water solubility and low octanol/water partition coefficient of the submitted substance are supporting of a systemic distribution at least in the aqueous tissues.

 

Metabolism:

In vitro genotoxicity studies were performed on the submitted substance. These studies showed no genotoxic potential but did not provide any information on possible metabolism.

 

Elimination:

There is no information to indicate a route of excretion for the submitted substance but its high water solubility and low octanol/water partition coefficient suggest that excretion of unchanged parent substances and/or metabolites could occur by renal or biliary routes and that bioaccumulation is unlikely. The parent substances could not be eliminated via the lungs in expired air due to its low volatility.