Diphenyl methylphosphonate

Endpoint summary

Description of key information

OECD 203, GLP, semi-static, 96h, Oncorhynchus mykiss: nominal LC50(96h) 20 mg/L, NOEC 10 mg/L

OECD 202, GLP, static, 48h, Daphnia magna: EC50(48h) 1.3 mg/L

OECD 201, GLP, 72h, Pseudokirchneriella subcapitata: Er10(72h) 3.1 mg/L, ErC50(72h) 15 mg/L

Additional information

The acute aquatic toxicity testing of Diphenyl methylphosphonate (DPP) was investigated in three different aquatic trophic levels (i.e. fish, daphnids and algae). Every investigation was conducted under certificated GLP compliance. In each experiment, the corresponding validity criteria were fulfilled and the test substance preparations were observed to be clear colorless solutions. Verifications of the test concentrations and stability were performed using High Performance Liquid Chromatography with UV detection (HPLC-UV).

Oncorhynchus mykiss was used as test organism in an experiment conducted in accordance with OECD Guideline 203 / EU Method C.1 (Harris, 2013). Based on a preliminary range-finding test, the animals were exposed to test concentrations of 10, 18, 32, 56 and 100 mg/L. A semi-static test regime was employed over a period of 96 hours. As final result, the LC50(96h) is given as 20 mg/L with a 95 % Confidence Limit of 17 - 25 mg/L. The Lowest Observed Effect Concentration (LOEC) was considered to be 18 mg/L. The No Observed Effect Concentration (NOEC) was 10 mg/L. All test concentrations are given as nominal results. The validity criteria given in the applied guideline were fulfilled.

The acute toxicity towards aquatic invertebrates was tested with Daphnia magna in accordance to OECD Guideline 202 / EU Method C. 2 (Harris, 2013). Based on a range-finding test, the definitive test was performed with the following test concentrations: 1.0, 1.8, 3.2, 5.6 and 10 mg/L. Static test conditions were applied for an exposure duration of 48 h. As final result, the EC50(48h) is given as 1.3 mg/L with a 95 % Confidence Limit range of 1.0 - 1.8 mg/L.

Pseudokirchneriella subcapitata was used as test organism in order to determine the toxicity of Diphenyl methylphosphonate (DPP) towards freshwater algae (Vryenhoef, 2013). The experiment was performed in accordance to OECD Guideline 201 / EU Method C.3. After a preliminary range-finding test, the substance concentrations for the definitive test were chosen as: 1.0, 3.2, 10, 32 and 100 mg/L. Considering the inhibition of growth rate, the following results were obtained: ErC10(72h): 3.1 mg/L, ErC20(72h): 5.6 mg/L and ErC50(72h): 15 mg/L (with 95 % CL: 12 – 19 mg/L). Yield inhibition determinations gave the following results: EyC10(72h): 7.1 mg/L, EyC20(72h): 7.5 mg/L and EyC50(72h): 8.4 mg/L (these data did not fit the models available for the calculation of confidence limits). For each method, the NOEC(72h) was determined as 3.2 mg/L and the LOEC as 10 mg/L.

 

In Annex IX of REACH Regulation (EC) No. 1907/2006, it is laid down that long-term toxicity testing in aquatic organisms shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate further the effects observed. The available short-term experiments described reveal, together with the hazard assessment of Diphenyl methylphosphonate (DPP), the need to classify the substance as dangerous to the environment. Based upon the CSA and animal-welfare considerations, long-term investigations are waived in accordance with REACH, Annex IX, Section 9.1.5, column 2 (daphnids) and REACH, Annex IX, Section 9.1.6, column 2 (fish).

 

Experimental investigations concerning aquatic microorganisms are also not triggered, since Diphenyl methylphosphonate (DPP) is not sold as monomer. Indirect exposure to the sewage treatment plant is unlikely, which is also indicated by the manufacturing process. Therefore, this endpoint can be waived in accordance to REACH, Annex VIII, Section 9.4.1., column 2.