Fatty acids, C14-18 and C16-18-unsatd., esters with neopentyl glycol

Toxicity to terrestrial arthropods

Description of key information

The chemical safety assessment according to Annex I of Regulation (EC) No. 1907/2006 does not indicate the need to investigate further the toxicity to terrestrial arthropods. 

Additional information

No experimental data on toxicity to terrestrial arthropods are available for NPG esters. According to the Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance, where there is no toxicity in the standard acute aquatic toxicity tests, a single soil test on a suitable species would be adequate to meet the requirements of Annex IX (ECHA, 2012). In the case of NPG esters, no toxicity was observed in the acute aquatic studies. The substances are characterised by a high log Koc (> 3), indicating a considerable potential for adsorption to the soil particles. Therefore, tests with soil-dwelling organisms that feed on soil particles are most relevant for the evaluation of soil toxicity of NPG esters. As stated in the Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance, earthworm testing allows potential uptake vie each of surface contact, soil particle ingestion and pore water (ECHA, 2012). The Guidance also states that in absence of clear indication of selective toxicity, an invertebrate (earthworm or collembolan) is preferred. Therefore, the earthworm was chosen as the most suitable test organism for NPG esters.

All NPG esters are readily biodegradable and are thus expected to be removed from the terrestrial environment within a short period of time. A short-term study according to OECD 207 is therefore conducted with the smallest NPG ester Heptanoic acid, ester with 2,2-dimethyl-1,3-propanediol (CAS No. 68855-18-5) (log Koc < 5). Due to its smaller size and lower adsorption potential, this substance is assumed to represent the worst case for NPG esters in terms of highest bioavailability. The water solubility is negatively correlated with the C-chain of fatty acids (Lide, 2005). It was therefore used as read-across for all NPG esters. However, since the larger NPG esters have higher adsorption potential (log Koc > 5), a long-term study according to OECD 222 is conducted with one of the largest NPG esters 2,2-dimethyl-1,3-propanediyl dioleate (CAS No. 42222-50-4). This substance represents a worst case for the uptake via ingestion of soil particle bound substance and in terms of longest stability in soil. Summarising, NPG esters present in soil pore water will be readily degraded by microorganism, and long-term exposure is not to be expected. The short-term study is therefore considered sufficient in this case. For highly sorptive substances, which are not expected to be found in pore water (log Koc >5) a long-term study is available. However, these substances are readily biodegradable as well, so if they were to be found in pore water, removal via rapid biodegradation would take place. The two test substances thus represent both ends of the group, and the results will be used to cover all other NPG esters by interpolation.

Furthermore, in a chronic study on Daphnia magna, available for the NPG ester 2,2 -dimethyl-1,3 -propanediyl dioleate (CAS No. 42222 -50 -4), no long-term effects were observed at the test concentration of 1 mg/L, which is far above the water solubility of the NPG esters.

Also, since NPG esters are readily biodegradable, they are expected to be rapidly eliminated from the terrestrial environment.

Based on the available data, terrestrial toxicity is not of concern for NPG esters.

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