Phosphoric acid, mono- and di-C11-14 (linear and branched) alkyl esters

Short-term toxicity to fish

Description of key information

The acute toxicity of the test material to the freshwater fish rainbow trout has been investigated anf gave a 96-hour LC50 value of 24 mg ai/L with 95% confidence limits of 18-32 mg ai/L. The No Observed Effect Concentration was 18 mg ai/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

24 mg/L

Additional information

A study was performed to assess the acute toxicity of the test material to rainbow trout (Oncorhynchus mykiss). The method followed that described in the OECD Guidelines 203 (1992) and Method C.1. Following a preliminary range-finding test, fish were exposed, in groups of seven, to an aqueous dispersion of the test material over a range of concentrations of 10, 18, 32, 56 and 100 mg ai/L for a period of 93 hours at a temperature of approximately 14ºC under semi-static test conditions with daily renewal. The number of moratlities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours. The 96 -Hour LC50 based on nominal test concentrations was 24 mg ai/L with 95% confidence limits of 18 -32 mg ai/L. No Observed Effect Concentration was 18 mg ai/L.

Rationale for Read-across

The key study on acute toxicity to fish was made with the read-across source substance "Phosphoric acid, C12-15-branched and linear alkyl esters, sodium salts". The test substance has a sufficient simmilar chemical structure compared to the registration substance:

• comparable C-chain length distribution
• comparable ratio of mono/di/tri-alkyl ester
• comparable identiy and amount of by-products

Differences between test and registration substance:

• the test substance is the sodium salt of the registration substance. It contains sodium cations and the corresponding base of the phosphoric acid ester. The registration substance has 2 protons that, in aqueous solution, will easily protonate water molecules, resulting in the same corresponding base of the phosphoric acid ester and H3O+.
• aqueous solution of the test substance has a neutral to slightly basic pH (see description of fish test) whereas the the aqueous solution of the registration substance has low pH During the fish test, according to guideline OECD201, low pH of aqueous test preparation is adjusted to higher pH. For this the use of NaOH is recommended. The solution from pH adjustment of the registration contains the same ionic species as the aqueous solution of the test substance.

Conclusion

No different test results are expected from the source substance test compared to the registration substance test as a consequence of identical chemical species in the test preparation.