Hydrocarbons, C9-C11, n-alkanes, isoalkanes,

Endpoint summary

Description of key information

Hydrolysis:

Hydrolysis is a reaction in which a water molecule or hydroxide ion substitutes for another atom or group of atoms present in a chemical resulting in a structural change of that chemical. Potentially hydrolyzable groups include alkyl halides, amides, carbamates, carboxylic acid esters and lactones, epoxides, phosphate esters, and sulfonic acid esters. The lack of a suitable leaving group renders compounds resistant to hydrolysis.

The chemical constituents that comprise Hydrocarbons, C9-C11, n-alkanes, isoalkanes, <2% aromatics consist entirely of carbon and hydrogen and do not contain hydrolyzable groups. As such, they have a very low potential to hydrolyze. Therefore, this degradative process will not contribute to their removal from the environment.

Phototransformation in air:

Standard tests for atmospheric oxidation half-lives are intended for single substances and are not appropriate for this complex substance. However,this endpoint is characterized using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with the PETRORISK model (see library tab in PETRORISK spreadsheet attached to Section 13).

Phototransformation in water and soil:

The direct photolysis of an organic molecule occurs when it absorbs sufficient light energy to result in a structural transformation. The absorption of light in the ultra violet (UV)-visible range, 110-750 nm, can result in the electronic excitation of an organic molecule. The stratospheric ozone layer prevents UV light of less than 290 nm from reaching the earth's surface. Therefore, only light at wavelengths between 290 and 750 nm can result in photochemical transformations in the environment.

A conservative approach to estimating a photochemical degradation rate is to assume that degradation will occur in proportion to the amount of light wavelengths >290 nm absorbed by the molecule. This substance contains hydrocarbon molecules that absorb UV light below 290 nm, a range of UV light that does not reach the earth's surface. Therefore, this substance does not have the potential to undergo photolysis in water and soil, and this fate process will not contribute to a measurable degradative loss of this substance from the environment.

Biodegradation:

No measured biodegradation data are available for the registration substance itself. However, reliable data are available for related substances in the relevant carbon number range, including studies on similar Fischer-Tropsch process-derived materials (GTL Solvent GS160 and GTL Solvent GS170).

In an OECD 301F manometric respirometry test conducted in compliance with GLP, Hydrocarbons, C9-C12, n-alkanes, isoalkanes, <2% aromatics (GTL Solvent GS170) attained 80% degradation in 28 days (Vryenhoef, 2014a). The 10-day window criterion is not applicable for complex substances where sequential degradation of the constituents takes place (REACH guidance R.7b ECHA, 2017). The substance was therefore concluded to be readily biodegradable.

Hydrocarbons, C8-C11, n-alkanes, isoalkanes, <2% aromatics (GTL Solvent GS160) has been tested in an OECD 301F (manometric respirometry) test conducted in compliance with GLP (Best, 2014). The test substance attained 73% biodegradation in 28 days and was therefore considered to be readily biodegradable.

These studies are considered to be reliable and are used as weight of evidence that Hydrocarbons, C9-C11, n-alkanes, isoalkanes, <2% aromatics is readily biodegradable.

In a supporting study, Hydrocarbons, C9-C11, n-alkanes, isoalkanes, cyclics, <2% aromatics, biodegraded 80% after 28 days under the conditions of the study and is readily biodegradable.

The available data cover the entire carbon number range relevant to the registration substance and the test materials contain similar chemical structures. The results are therefore read across to Hydrocarbons, C9-C11, n-alkanes, isoalkanes, <2% aromatics. Both tested substances demonstrated significant biodegradation and it can therefore be concluded that the registration substance is readily biodegradable.

Adsorption / desorption:

Substance is a hydrocarbon UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance. However, this endpoint is characterized using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with the PETRORISK model version 7.04 (see Product Library in PETRORISK spreadsheet attached to Section 13).

Distribution modelling:

The distribution of the substance in the environmental compartments, air, water, soil, and sediment, has been calculated using the PETRORISK Model, version 7.04 Computer modelling is an accepted method for estimating the environmental distribution of chemicals. Based on the regional scale exposure assessment, the multimedia distribution of Hydrocarbons, C9-C11, n-alkanes, isoalkanes, <2% aromatics is 80% to air, 4.4% to water, 2.5% to soil and 13% to sediment. Distribution modelling results are included in the 'Multimedia distribution modelling results' tab in the PETRORISK spreadsheet attached to Section 13 of the CSR.