2-Propenoic acid, 2-methyl-, C11-14-isoalkyl esters, C13-rich

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar physicochemical, ecotoxicological and toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: methacrylate esters
• the metabolism pathway leads to comparable products (methacrylic acid and medium chain alcohol).

Therefore, read-across from the existing physicochemical, ecotoxicity and toxicity studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see “Justification for read-across” attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see “Justification for read-across” attached to IUCLID section 13

4. DATA MATRIX
see “Justification for read-across” attached to IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Test temperature:

20 ± 2 °C

Type:

Koc

Value:

>= 2 040 - <= 51 000 L/kg

Temp.:

20 °C

Conclusions:

Koc, values at all solution:soil ratios were > 1000 which, in spite of the variability, indicate a tendency of the material to sorb strongly to solids. This tendency indicates that the material may be expected to be immobilized in soil when introduced into the environment. Desorption concentrations were not determined in this test.

Additional information

No experimental data on Isotridecyl methacrylate are available for the assessment of sorption properties potential. However, a study is available for the source substance Dodecyl methacrylate. A detailed justification for read-across is attached to IUCLID section 13.

 

Dodecyl methacrylate demonstrated high but variable sorption in this test. Koc values at all solution:soil ratios were > 1000 which, in spite of the variability, indicate a tendency of the material to sorb strongly to solids. This tendency indicates that the material may be expected to be immobilized in soil when introduced into the environment.

 

Hypothesis for the analogue approach

The read-across hypothesis relies on the close structural similarity between the source substance Dodecyl methacrylate and the target substance Isotridecyl methacrylate. This read-across hypothesis corresponds to scenario 2 - different compounds have qualitatively similar properties - of the read-across assessment framework i.e. properties of the target substance are predicted to be quantitatively equal to those of the source substance. Namely, the structurally similar source substance Dodecyl methacrylate predicts the environmental fate properties of the target substance Isotridecyl methacrylate.

 

Experimental data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

 

Therefore, read-across from the existing environmental fate studies conducted with the source substance is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

A detailed justification for the proposed read-across approach is attached to Iuclid section 13.

 

1. Identity and characterisation of the source substance

 

There is close structural similarity between the source and the target substances and the identity and characterisation of these substances is unambiguous thereby giving a high level of confidence in the validity of the read across.

The target and source substances are manufactured from similar compounds by esterification of methacrylic acid with the corresponding fatty alcohol. Typical trace impurities are water and the corresponding alcohols as well as < 1 % methacrylic acid, which are not of toxicological concern.

The carbon chain length distribution of the resulting mix of long-chain aliphatic methacrylate esters mirrors the chain length distribution of the alcohol(s) used.

 

2. Link of structural similarities and differences with the proposed prediction

Structural similarities:

The target substance Isotridecyl methacrylate is an ester of Methacrylic acid and branched C12-C18 alcohols. The source substance Dodecyl methacrylate is of comparable chain length (C12).

 

Structural differences:

In contrast to the target substance, which contains mainly branched alkyl chains, the source substanceDodecylmethacrylate contains only linear alkyl chains. This is not considered to have a relevant influence on sorption properties.

There are differences in alkyl chain length between the target and the source substances.The physicochemical properties (low water solubility <1µg/L and high log Kow > 6.5) of the target and source substance are, however, very similar. Thus, no large differences in sorption properties are expected.

 

Reliability and adequacy of the source data

All available studies have been conducted according to OECD guidelines and have been assigned a reliability of 1 or 2 as documented in the data matrix (see detailed justification for read-across attached to Iuclid section 13).

 

Overall, the study design of the respective source studies is adequate and reliable for the purpose of this read-across. The results of the study are adequate for classification and labelling and for risk assessment purposes.

 

Data availability

The sorption properties of Dodecyl methacrylate were determined in accordance with OECD Guideline 106 (1981). Preliminary testing was performed in duplicate with Kansas silty clay loam using 0.01 M CaCl2, and solution:soil ratios ranging from 5:1 to 200:1. The initial solution concentration of 5 mg/L proved to be in excess of water solubility for Dodecyl methacrylate: measurement of test substance concentration in prepared solutions by HPLC-UV typically resulted in values around 1 mg/L. Following 16 hours of equilibration, the majority of the test substance had sorbed to the glass test vessels and/or Teflon-lined caps. Of the amount not sorbed to glass, 52.1 to 86.1% had sorbed to the soil at the varying solution:soil ratios, with no apparent relationship between sorption rate and soil mass. Koc-, values ranging from 2040 at a 5:1 solution:soil ratio to 51000 at a 200:1 solution:soil ratio were calculated. Neither desorption from the silty clay loam nor sorption to other soil types was evaluated, due to the low solubility of the test substance and highly variable analytical results. Based on the estimates obtained, Dodecyl methacrylate is highly sorbed and may be expected to be immobilized in soil when introduced into the environment.