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

Short-term toxicity to aquatic invertebrates

Description of key information

Effect concentrations based on nominal concentration:
24 h EC50 > 100 mg/L
48 h EC50 = 6.31 mg /L (95 % CL: 4.30 - 9.18 mg/L)
48 h NOEC = 1.0 mg/L

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.31 mg/L

Additional information

The 48hr acute toxicity of the read-across source substance MAP-115K(H) to water flea (Daphnia magna) according to OECD 202 (Acute Immobilisation Test for Daphnia) was studied under static conditions. Daphnids were exposed to control, and MAP-115K(H) at nominal concentration of 0.3, 1, 3, 10, 30 and 100 mg test mat./L for 48 hr. Mortality/immobilization was observed daily. The 48 – hour EC50was 6.31 mg a.i./L (95 % CL: 4.30 - 9.18 mg/L). And 24 h EC50 was > 100 mg/L, 48 h NOEC was 1.0 mg/L.

This study is classified as reliable with restriction and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Rationale for Read-across

The key study on acute toxicity to fish was made with the read-across source substance: Phosphoric acid, C9-11-branched and linear alkyl esters, potassium and Phosphoric acid, C13-15-branched and linear alkyl esters,

potassium salts; 50/50.

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 source substance is the potassium salt of the registration substance. It contains potassium 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 with one exception: instead of Na+ the test preparation contains K+. It is expected, that this difference will not influence the test result.

Conclusion

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