Hydrocarbons, C13-C15, n-alkanes, isoalkanes, cyclics, < 2% aromatics

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, C13 -C15, n-alkanes, isoalkanes, cyclics, < 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 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, C13 -C15, n-alkanes, isoalkanes, cyclics, < 2% aromatics contain hydrocarbon molecules that absorb UV light below 290 nm, a range of UV light that does not reach the earth's surface. Therefore, these substances do not have the potential to undergo photolysis in water and soil, and this fate process will not contribute to a measurable degradative loss of these substances 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, C13 -C15, n-alkanes, isoalkanes, cyclics, < 2% aromatics contain hydrocarbon molecules that absorb UV light below 290 nm, a range of UV light that does not reach the earth's surface. Therefore, these substances do not have the potential to undergo photolysis in water and soil, and this fate process will not contribute to a measurable degradative loss of these substances 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. The data support characterizing Hydrocarbons, C11-C14, n-alkanes, isoalkanes, cyclics, <2% aromatics as rapidly biodegradable, readily biodegradable, not expected to persist in the environment under aerobic conditions. Although it did not meet the 10-day window requirement, it is characterized as readily biodegradable because the criterium is not applied to multi-component substances when assessing their ready biodegradability.

Hydrocarbons, C12-C16, n-alkanes, isoalkanes, cyclics, <2% aromatics, a multi-component substance, biodegraded to an extent of 68% after 28 days and 69% after 31 days. The data support characterizing Hydrocarbons, C12-C16, n-alkanes, isoalkanes, cyclics, <2% aromatics as rapidly biodegradable, readily biodegradable, not expected to persist in the environment under aerobic conditions. Although it did not meet the 10-day window requirement, it is characterized as readily biodegradable because the criterium is not applied to multi-component substances when assessing their ready biodegradability.

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.

 

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 the tested substances are readily biodegradable. Data is available from a Guideline (OECD 304 A) study conducted on Hydrocarbons, C11 -C14, n-alkanes, isoalkanes, cyclics, <2% aromatics and 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.

 

Bioaccumulation: aquatic/sediment:

Hydrocarbons, C13 -C15, n-alkanes, isoalkanes, cyclics, <2% aromatics are hydrocarbon UVCBs. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance. However, this endpoint is fulfilled using quantitative structure property relationships for representative hydrocarbon structures. The BCFBAF 3.01 model is a well characterised and generally accepted bioaccumulation prediction model, used by the USEPA, the OECD and recommended by ECHA. The SMILES input data for the BCFBAF 3.01 model is obtained from the PETRORISK Product Library (see OECD QSAR Toolbox report in 'Attached full study report' and PETRORISK report attached in IUCLID section 13).

The calculated BCF of Hydrocarbons, C13 -C15, n-alkanes, isoalkanes, cyclics, <2% aromatics ranges from 6.91 - 6299.66 L/kg.

Adsorption / desorption:

Hydrocarbons, C13 -C15, n-alkanes, isoalkanes, cyclics, <2% aromatics are hydrocarbon UVCBs. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance. However, this endpoint is characterised 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 Product Library in PETRORISK report attached in IUCLID section 13).

Adsorption coefficient has been calculated using Petrorisk.  The Koc for Hydrocarbons, C13 -C15, n-alkanes, isoalkanes, cyclics, <2% aromatics ranges from 5.13 x 10^1 - 5.50 x10^6.

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.

 

Distribution modelling 

Based on the regional scale exposure assessment, the multimedia distribution of Hydrocarbons, C13-C15, n-alkanes, isoalkanes, cyclics, <2% aromatics is 3.9 % to air, 1.1 % to water, 8.9 % to soil and 86.1 % to sediment.