Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Justification for grouping of substances and read-across

The short chain methyl esters category (SCAE Me) covers fatty acid esters of methanol. The category contains both mono-constituent substances, with fatty acid C-chain lengths ranging from C6 to C18 and UVCB substances, composed of single methyl esters in variable proportions. Fatty acid esters are generally produced by chemical reaction of an alcohol (e.g. methanol) with a fatty acid (e.g. lauric acid) in the presence of an acid catalyst (Radzi et al., 2005). The esterification reaction is started by the transfer of a proton from the acid catalyst to the acid to form an alkyloxonium ion. The carboxylic acid is protonated on its carbonyl oxygen followed by a nucleophilic addition of a molecule of the alcohol to the carbonyl carbon of the acid. An intermediate product is formed. This intermediate product loses a water molecule and proton to give an ester (Liu et al., 2006; Lilja et al., 2005; Gubicza et al., 2000; Zhao, 2000). Monoesters are the final products of esterification of fatty acids with methanol.

The available data allows for an accurate hazard and risk assessment of the category and the category concept is applied for the assessment of environmental fate, environmental and human health hazards. Thus where applicable, environmental and human health effects are predicted from adequate and reliable data for source substance(s) within the group by interpolation to the target substances in the group (read-across approach) applying the group concept in accordance with Annex XI, Item 1.5, of Regulation (EC) No 1907/2006. In particular, for each specific endpoint the source substance(s) structurally closest to the target substance is/are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across.

A detailed justification for the grouping of chemicals and read-across is provided in the technical dossier (see IUCLID Section 6.1 and Section 13) and within chapter 7.1 of the CSR.

Table 3. Terrestrial toxicity parameters of the SCAE Me category

CAS

Toxicity to soil macroorganisms except arthropods

Toxicity to terrestrial arthropods

Toxicity to terrestrial plants

Toxicity to soil microorganisms

106-70-7 (a)

RA: CAS 111-82-0

Waiving based on CSA

Waiving based on CSA

Weight of Evidence (WoE)

111-11-5

RA: CAS 111-82-0

Waiving based on CSA

Waiving based on CSA

Weight of Evidence (WoE)

110-42-9

RA: CAS 111-82-0

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

111-82-0

Experimental result:
NOEC (56 d) = 1000 mg/kg dw

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

112-39-0

Experimental result:
NOEC (56 d) ≥ 1000 mg/kg dw

Waiving based on CSA

Waiving based on CSA

Weight of Evidence (WoE)

112-61-8

--

--

--

--

308065-15-8

RA: CAS 111-82-0

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

1234694-02-0

RA: CAS 111-82-0

RA: CAS 112-39-0

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposure assessment

Waiving based on CSA and exposureassessment

85586-21-6

RA: CAS 112-39-0

Waiving based on CSA

Waiving based on CSA

Weight of Evidence (WoE)

 

Two long-term toxicity studies performed according to OECD 222 on soil macroorganisms (Eisenia fetida) are available for methyl laurate (CAS 111-82-0) and methyl palmitate (CAS 112-39-0)(Winkelmann, 2013). Both studies reported no significant effects on earthworm reproduction, survival and growth, leading to NOEC values ≥ 1000 mg/kg dw. The majority of the SCAE Me category members have log Koc values > 3, indicating potential for adsorption to soil particles. Therefore, tests with soil-dwelling organisms that feed on soil particles (such as eathworms or arthropods) are most relevant for the evaluation of soil toxicity of these substances (Guidance on information requirements and chemical safety assessment, Chapter R7.c, ECHA, 2008). Furthermore, methyl laurate (CAS 111-82-0) exhibits the highest toxicity to aquatic organisms (Daphnia and algae) throughout the whole SCAE Me category, with EC50 and NOEC values < 1 mg/L. The lack of chronic toxicity of this substance on Eisenia fetida clearly indicates that toxicity to earthworms within the SCAE Me category is highly unlikely.

Additionally, literature data evaluating the effects of fatty acid esters in soil microorganisms, including a category member, methyl oleate (CAS 112-62-9)(Cecutti et al., 2002) are available. In this test, one soil sample was chosen and incubated with methyl oleate (plant oil) for 120 days. Methyl oleate and its metabolites were completely degraded after 60 days, indicating the lack of toxicity of the substance to soil microorganisms. This is supported by the results of the OECD 209 test performed on aquatic microorganisms with methyl laurate. No inhibition of respiration rate was observed in this study, leading to a NOEC (3 h) ≥ 1000 mg/L (nominal).The Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2008) states that a test on soil microbial activity is needed for PNEC derivation only in case inhibition of activated sludge microbial activity is observed (and this is clearly not the case).

The available information gathered from different taxonomic groups (earthworms and soil microorganisms) is considered sufficient to conclude that no toxicity to terrestrial organisms is to be expected for the SCAE Me category members.

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.