Hydrocarbons, C11-14, n-alkanes, isoalkanes, <2% aromatics

Endpoint summary

Description of key information

Abiotic degradation

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).

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, C11-C14, n-alkanes, isoalkanes, <2% aromatics do not contain hydrolyzable groups. As such, they have a very low potential to hydrolyze. Therefore, this degradative process will not contribute to the removal of this substance from the environment.

Phototransformation in water

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. Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics 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.

Phototransformation in 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. Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics 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 in water: screening tests

Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics, a multi-component substance, biodegraded to an extent of 69% after 28 days (Shell, 1997). This study is considered to be reliable and the data are used as read-across data for the registered substance, Hydrocarbons, C11-C14 n-alkanes, isoalkanes, <2% aromatics.

Biodegradation in water and sediment: simulation tests

Biodegradation in water

Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics, biodegraded to an extent of 69% after 28 days in seawater that used the indigenous microorganisms in the seawater sample as a sole source of the inoculum. These data read across to Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics.

Biodegradation in sediment

Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics is readily biodegradable, based on read-across data. Therefore, simulation tests in sediment are not required.

Biodegradation in soil

In accordance with column 2 of REACH Annex IX, the simulation testing on ultimate degradation in soil does not need to be conducted as Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics is readily biodegradable, based on read-across data. No data are available for Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics. However, data are available from an OECD 304A Test Guideline study conducted on Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics and this study is presented below.

Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics, biodegraded to a great extent (>60%) in a silt loam soil at a rate comparable to the control, rapeseed oil (62 to 67%), within a two month test period as measured in respirometric oxygen consumption tests. The half-life, based on three tests was 45 days. This extent was replicated in two separate studies. These data are used as read-across data for Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics).

Bioaccumulation: aquatic/sediment

This endpoint has been calculated for representative hydrocarbon structures including constituents of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics using the BCFWIN v2.16 model within EPISuite 3.12 as input to the hydrocarbon block method incorporated into the PETRORISK model. The predicted BCFs for hydrocarbons are generally overly conservative since biotransformation is not quantitatively taken into account. Therefore, indirect exposure and resulting risk estimates predicted by PETRORISK are likely to be overestimated. For the purposes of PBT assessment, measured bioaccumulation data for representative hydrocarbon constituents including the substance have been used as detailed in PETRORISK spreadsheet attached to IUCLID section 13.

The QSAR used to calculated the constituents of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% followed the Reach guidance indications (R7.10.3.2) and so is deemed suitable for the assessment of bioconcentration.

Bioaccumulation: terrestrial

This endpoint has been calculated for representative hydrocarbon structures including constituents of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics using the BCFWIN v2.16 model within EPISuite 3.12 as input to the hydrocarbon block method incorporated into the PETRORISK model. The predicted BCFs for hydrocarbons are generally overly conservative since biotransformation is not quantitatively taken into account. Therefore, indirect exposure and resulting risk estimates predicted by PETRORISK are likely to be overestimated. For the purposes of PBT assessment, measured bioaccumulation data for representative hydrocarbon constituents including the substance have been used as detailed in PETRORISK spreadsheet attached to IUCLID section 13.

Adsorption / desorption

Hydrocarbons, C11-C14 n-alkanes, isoalkanes <2% aromatics 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 these substances with the PETRORISK model 7.04 (see Product Library  in PETRORISK spreadsheet attached to Section 13 of the dossier). Calculated log Koc for constituents of this substance range between 3.44 and 6.35.

Volatilisation

Volatilisation is dependent on Henry's Constant (HC) which is not applicable to complex substances. However, HC values for representative structures are included in the PETRORISK spreadsheet attached to IUCLID Section 13. The HC for Hydrocarbons, C11-C14 n-alkanes, isoalkanes, <2% aromatics ranges from 0.02 to 12.42 atm-m3/mol

Distribution modelling

The distribution of Hydrocarbons, C11-14 n-alkanes, isoalkanes, <2% aromatics in the environmental compartments, air, water, soil, and sediment, has been calculated using the PETRORISK Model, version 5.2/5.3. Computer modeling is an accepted method for estimating the environmental distribution of chemicals. Distribution modelling results are included in the 'Multimedia distribution modelling results' tab in the PETRORISK spreadsheet attached to IUCLID section 13.

Based on the regional scale exposure assessment, the multimedia distribution of Hydrocarbons, C11-C14, n-alkanes, isoalkanes, <2% aromatics is 29% to air, 2.6% to water, 9.1% to soil and 60% to sediment.