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Environmental fate & pathways

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Biodegradation study:

A study was performed to assess the inherent biodegradability of the test material in an aerobic aqueous medium. The method followed the recommendations of CONCAWE (October 1999) "A Test Method to Assess the Inherent Biodegradability of Oil Products" and the draft OECD Guideline (October 2001) No 302D "Inherent Biodegradability: CONCAWE Test".

The test material, at a concentration of 20 mg C/l, was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at 20 ± 1°C for 56 days.

Data supplied by the Sponsor indicated that the bulk solubility of the test material was 1.1 mg/l therefore following the recommendations of the Test Guidelines for dealing with insoluble test materials, the test material was dissolved in a volatile organic solvent and an aliquot of the solvent stock solution applied to a glass fibre filter paper. After evaporation of the solvent, the filter paper containing the test material was added to the test medium.

The degradation of the test material was assessed by the determination of carbon dioxide produced on Days 0, 1, 2, 3, 6, 8, 10, 14, 21, 28, 35, 42, 49 and 56, and by compound specific analyses on Days 0, 1, 2, 3, 6, 8, 10, 14, 21, 42 and 56. Control solutions with inoculum and the standard material, n-Hexadecane, together with a toxicity control were used for validation purposes.

The test material attained 10% biodegradation after 56 days based on carbon dioxide production and therefore cannot be considered to be inherently biodegradable.

The results of the compound specific analyses indicated that no significant chemical or biological degradation of the test material occurred.

Bioaccumulation study:

Steady-state TPP concentrations were achieved in the tissues of rainbow trout (Oncorhynchus mykiss) after 3 days for both the 1.1 and 11 μg/L treatment groups.

Steady-state BCF values based on total radioactivity TPP concentrations were 289, 1601 and 823 in edible, nonedible and whole fish tissue, respectively, for the 1.1 μg/L treatment group, and 289, 1428 and 749 in edible, nonedible and whole fish tissue, respectively, for the 11 μg/L treatment group. Steady-state BCF values based on TPP chain lengths for the 1.1 μg/L treatment group were 209 and 544 for the C5 – C10 edible and nonedible fraction, 362 and 786 for the C11 – C12 edible and nonedible fraction, and 426 and 987 for the C13 and greater edible and nonedible fraction, respectively. Steady-state BCF values were 217 and 603 for the C5 – C10 edible and nonedible fraction, 388 and 845 for the C11 – C12 edible and nonedible fraction, and 423 and 936 for the C13 and greater edible and nonedible fraction, respectively for the 11 μg/L treatment group. During depuration, TPP was eliminated quickly with mean tissue concentrations 10% or less than the mean measured steady-state test concentrations by Day 11.

Adsorption Study:

The Adsorption Coefficient was determined to be 10.4 to 4.71 x 104, log10Koc1.02 to 4.67, using the HPLC screening method, designed to be compatible with Method C19 Adsorption Coefficient of Council Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

However, 93.9% of the test item (the dominant components) had a reduced range of 2.49 to 4.71 x 104, log10Koc4.40 to 4.67, using the HPLC screening method, designed to be compatible with Method C19 Adsorption Coefficient of Council Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.