Reaction mass of 2-(3-ethylphenyl)oxirane and 2,2’-(1,3-phenylene)dioxirane and 2,2'-(1,4-phenylene)dioxirane

Endpoint summary

Additional information

Hydrolysis: Assessment of hydrolytic stability was carried out using Method C7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 with the following deviation:

To maximise the efficiency of the procedure for the pH 4 testing at 10.0°C and 20.0°C, sample preparation having to be performed as rapidly as possible, samples were taken for analysis directly from a single stock solution incubated in the bath as opposed to using individual vessels for each time point. This was concluded not to impact on the validity of the data, as the use of individual vessels is required as a precautionary step against losses through volatility and biodegradation, neither of which were relevant over the temperature and time scale of the tests. When the procedure of splitting the sample solution between individual vessels was applied to the pH 4 preliminary test at 50°C, significant hydrolysis occurred even before sampling for the initial time point due to the delay introduced by this step.

Under the physiologically relevant conditions of pH 1.2, 37.0 ± 0.5°C, the test material was determined to undergo essentially spontaneous hydrolysis.

HPLC analysis of complete hydrolysis of the test substance successfully detected the presence of the anticipated hydrolysis products in the form mass ions of m/z 221 and 237, representative of the sodium adduct and potassium adduct of the diols anticipated from oxirane, 2,2’-(1,3-phenylene)bis- and oxirane, 2,2’-(1,4-phenylene)bis-. Sodium and potassium ions are unavoidable contaminants in an HPLC-MS system and often these ion pair adducts are significantly more stable than the parent ion alone. Further HPLC investigation successfully confirmed the lesser anticipated hydrolysis products, the diols originating from the oxirane, 2-(3-ethylphenyl)- and oxirane, 2-(4-ethylphenyl)- components, detected in the form of the mass ions of m/z 189 and 205, representative of the sodium adduct and potassium adduct of the diols anticipated from oxirane, 2-(3-ethylphenyl)- and oxirane, 2-(4-ethylphenyl)-.

Biodegradation:

The test material attained 16% mineralisation after 28 days based on CO2 evolution and is therefore not considered as readily biodegradable under the strict terms and conditions of the OECD Guideline No. 301B.

However, the test material attained 16% degradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.

Partition Coefficient: The partition coefficient of the test material has been determined to be 22.9 to 475, log₁₀ P_ow 1.36 to 2.68.

Since the log₁₀ P_ow is < 3, the test material does not have the potential to bioaccumulate.

Adsorption/Desorption:

Adsorption/ desorption was the only endpoint assessed at this level as regards transport and distribution.The determination was carried out using the HPLC screening method, Method C19 Adsorption Coefficient ofCommissionRegulation (EC) No 440/2008 of 30 May 2008. 

The adsorption coefficient (K_oc) of the test material has been determined to be 64.4 to 318, log₁₀K_oc 1.81 to 2.50.This is an indication that the substance is unlikely to adhere to soil particles in the environment.

Conclusion:

Based on the fact that:

(i)The test material attained 16% degradation based on CO2 evolution after 28 days and 45% based on DOC removal. It is therefore not considered 'readily biodegradable' under the strict terms and conditions of OECD Guideline No 301B.

(ii)The acute toxicity of the test material to the freshwater fish rainbow trout has been investigated and gave a 96 -hour LC50 value of 2.4 mg/L.

(iii)The acute toxicity of the test material to the freshwater invertebrate Daphnia magna has been investigated and gave a 48-Hour EC50 value of 1.2 mg/L,

 

the substance is classified as R51/R53: may cause long-term adverse effects on the aquatic environment.