Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated

Sediment toxicity

Description of key information

LC50 (10d) > 12,187 mg/kg dw (nominal) (Corophium sp., OSPAR Part A), RA
NOEC (10d) = 6095 mg/kg dw (nominal) (Corophium sp., OSPAR Part A), RA
No effects up to the limit of the water solubility of the substance.No effects on long-term toxicity to sediment organisms are to be expected.

Additional information

There are no data available on the sediment toxicity of Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5). According to the standard requirements set in Regulation (EC) No. 1907/2006, Annexes VII-IX information regarding sediment toxicity does not need to be presented at this tonnage band (100-1000 t/y). Nevertheless, in accordance with the Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012), toxicity to sediment organisms should be considered for highly hydrophobic substances (log Kow > 5) such as Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5). Therefore, read-across from a structurally similar substance is conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human and environmental toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, whereby physico-chemical, toxicological and ecotoxicological properties may be predicted from data for reference substance(s) by interpolation to other substances on the basis of structural similarity, Fatty acids, C18-unsatd., trimers (CAS 68937-90-6) is selected as read-across substance for assessment of sediment toxicity.

The read-across is based on structural similarity as a result of common origin and production process line. Shortly, the source and target substances are derived from catalytically di- and trimerised long-chain fatty acids; dimers and trimers are separated by distillation and unsaturated alkyl chains are hydrogenated as specifically required. A detailed analogue approach justification is provided in the Technical dossier (see IUCLID Section 13).

Table: Sediment toxicity of target and source substances

Name	Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (a)	Fatty acids, C18-unsatd., trimers(b)
CAS No.	147853-32-5	68937 -90 -6
Sediment toxicity	RA CAS 61788-89-4	Experimental result: LC50 > 12187 mg/kg dw NOEC = 6095 mg/kg dw

(a) The substance subject to the REACh Phase-in registration deadline of 31 May 2013 is indicated in bold font. Only for this substance a full set of experimental results and/or read-across is given.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

The key study conducted with Fatty acids, C18-unsatd., trimers (CAS 68937-90-6) was performed according to OSPAR guideline, Part A (Protocols on Methods for the Testing of Chemicals Used in the Offshore Oil Industry, Part A: A Sediment Bioassay using an Amphipod Corophium sp) and GLP (Staniland, 2005). The test organism Corophium sp. was exposed to the test substance at nominal concentrations of 764, 1524, 3047, 6095 and 12187 mg/kg dry (natural) sediment for 10 days. The NOEC was determined to be 6095 mg/kg dry sediment and the LC50 was determined to be > 12187 mg/kg dry sediment.

Based on the above mentioned results and due to the structural and profile similarities of the substances, the toxicity of Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) to sediment organisms is expected to be low.

Additionally, as Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5) has a very low water solubility (< 0.1 mg/L) and a high adsorption potential (log Koc 8.5). Thus only low concentrations of the substance are expected in the waste water, if present at all. These small concentrations will be further reduced in sewage treatment plants (STP) by adsorption to the sludge. Hence, if at all, only negligible quantities of the test substance are expected to be discharged to the aquatic environment by STP effluent.

Thus, due to the very low water solubility of Fatty acids, C18-unsatd., dimers, di-Me esters, hydrogenated (CAS 147853-32-5), sediments are not expected to be the compartment of highest exposure. However if exposure does occur, based on the lack of effects within the range of water solubility in the short-term aquatic toxicity tests, the long-term toxicity test on fish for Fatty acids, C18-unsatd., dimers, hydrogenated (CAS 68783-41-5) and the low toxicity to Corophium sp. in a short-term toxicity test with CAS 68937-90-6, long-term effects in sediment organisms are not expected. Thus, a long-term study with sediment organisms is not required.