Ditolyl ether

Endpoint summary

Description of key information

The toxicity to the terrestrial compartment of Ditolylether was investigated in three long-term studies (earthworm, plants and microogranisms) according to OECD TG 222, OECD TG 208 and OECD TG 216. While no effect was exhibited in the N-transformation test on soil microorganisms, effects were apparent in the earthworm reproduction test as well as in the seedling emergence and growth test. The lowest NOEC appeared in the seedling emergence and growth test with NOEC = 6.0 mg/kg soil dry weight (Solanum lycopersicum); which is hence further used for assessment.

Toxicity to terrestrial invertebrates

The test substance Ditolylether was tested according to OECD Guideline No. 222 for the Testing of Chemicals "Earthworm Reproduction Test (Eisenia fetida/Eisenia andrei)" adopted July 29, 2016 with eisenia fetida. The NOEC value for the endpoints mortality and reproduction were the same with 50 mg/kg soil dw. So were the LOEC values for the endpoints mortality and reproduction with 100 mg/kg soil dw, respectively. Regarding mortality, a LC50 of 87.1 g/kg soil dw and regarding reproduction a LC50 of 65.1 mg/kg soil dw are reported.

As the NOEC values for reproduction and mortality were the same, the value of 50 mg/kg soil was chosen for the assessment, in accordance with being the lowest value.

Toxicity to terrestiral plants

The effect of the test item Ditolyl ether on the emergence and growth of six species of higher terrestrial plants was tested accordig to OECD Guideline for the Testing of Chemicals No. 208; Terrestrial Plant Test: Seedling Emergence and Seedling Growth Test. The test item had no statistically significant effect on emergence except for Avena sativa for which an EC10 of 294.8 mg/kg soil dry weight could be determined. An effect on survival was seen with Allium cepa for which an LC10, LC50, LOEC and NOEC could be determined and with Brassica rapa for which an LC10 could be determined. No statistically significant effect on survival could be observed in any of the other test species.

Shoot fresh weight was statistically significantly reduced at test item concentrations of ≥18.0 mg/kg soil dry weight in S. lycopersicum, ≥54.0 mg/kg soil dw in B. rapa, and A. cepa, ≥72.0 mg/kg soil dw in C. sativus and P. sativum, and ≥216 mg/kg soil dw in A. sativa.

The lowest values for the end points EC10, EC50, LOEC and NOEC were

observed with shoot fresh weight of the test species Allium cepa, Pisum

sativum and Solanum lycopersicum. The values were as follows:

EC10 = 8.8 mg/kg soil dry weight (Pisum sativum)

EC50 = 41.9 mg/kg soil dry weight (Allium cepa)

LOEC = 18.0 mg/kg soil dry weight (Solanum lycopersicum)

NOEC = 6.0 mg/kg soil dry weight (Solanum lycopersicum)

Toxicity to soil microorganisms

The test item Ditolyl ether, was tested in accordance with OECD Guideline for the Testing of Chemicals No. 216 “Soil Microorganisms: Nitrogen Transformation Test".

Nitrate concentration in test-item treated soil measured on day 0 and on day 28 was not significantly reduced compared to the solvent control. On day 28 increasing nitrate concentrations were observed with increasing test item concentrations up to 128 mg/kg soil dw. At 512 mg/kg soil dw the nitrate concentration was comparable to the solvent control. Therefore the LOEC and NOEC were considered to be >512 mg/kg soil dw and ≥512 mg/kg soil dw, respectively.

Due to the lack of adverse effects on nitrate concentration in soil ECX values could not be determined. The EC50 is assumed to be higher than the highest tested concentration of 512 mg a.s./kg soil dw