Reaction mass of diisobutyl hydrogen phosphate and isobutyl dihydrogen phosphate

Endpoint summary

Additional information

The short term toxicity of the reaction mass (IBAP) on aquatic organisms is assessed by using a read-across with its potassium salt.

The reaction mass IBAP and its potassium salt have high water solubility and their behavior in water and biological systems is dominated by their ionization. The main assumption is that the potassium cation is not significant in respect of the toxicological effect on aquatic organisms which are expected to be related to the IBAP. In experimental dilute aqueous conditions at environmental pH (5-9), the salt will be completely dissociated and will not behave differently to the parent acid, at identical concentration of the particular speciated form present.

For the aquatic hazard assessment, some acute tests (algae, daphnids, fish and micro-organisms) were performed with the potassium salt having a similar composition than the target substance registered. The results on effects are expressed in nominal concentration of test item because the analytical measurement based on phosphate show that it was stable among the studies (fish, algae and invertebrates).

For the purpose of risk assessment, PBT/vPvB assessment and classification and labeling, the concentrations were not corrected for the target substance because the molecular weight of potassium was assessed to be negligible compared to the molecular weight of the other constituents of the reaction mass.

Short-term toxicity to fish

One reliable key study was available. In this 96-hour acute toxicity study, Danio Rerio was exposed to test item at a nominal concentrations of 100 mg/L under static conditions and mortality was recorded. The 96-h LC50 was >100 mg/L. Based on the results, the test item is considered to be non-toxic to fish.

Short-term toxicity to aquatic invertebrates

One reliable key study was available. In this 48-hour acute toxicity study, Daphnia Magna was exposed to test item at a nominal concentrations of 100 mg/L under static conditions, and immobilisation was recorded. The 48-h EC50 was >100mg/L. Based on the results, the test item is considered to be non-toxic to the invertebrates.

Toxicity to algae

One reliable key study was available. In this 72-hour acute toxicity study, Desmodesmus subspicatus was exposed to test item at nominal concentration of 100 mg/L under static conditions and algal cell concentration was determined. Based on growth rate, the 72-hour EC50 was >100 mg/L. The 72 -hour NOEC was >100 mg/L. Based on the results, the test item is considered to be non-toxic to the algae.

Toxicity to micro-organisms

One reliable key study was available. Based on the inhibition of the O2 consumption, the EC50 was >1000 mg/L. Based on the results, the test item is considered to be non-toxic to the tested microorganisms.