Sophorolipids: fermentation products of glucose and fatty acids, C18 (unsaturated), glycerol esters with yeast Candida Bombicola, partially hydrolysed

Endpoint summary

Description of key information

Short-term toxicity to fish (species tested: Danio rerio) 
Key study, OECD TG 203 (1992), GLP, RL1: The 96-h LC50 under semi-static conditions was 180 mg test item/L (nominal) or 85 mg/L a.i. (nominal). 

Long-term toxicity to invertebrates (Species tested: Daphnia magna)
Key study, OECD TG 211, GLP, RL1: The 21-d NOEC and LOEC were 25 mg/L and 50 mg test item/L (nominal), respectively. This refers to NOEC/LOEC = 11.7/23.4 mg/L based on active ingredient. Additionally, the EC50 was 38.8 mg/L based on active ingredient.

Toxicity to aquatic algae and cyanobacteria (Species tested: Pseudokirchneriella subcapitata)
Key study, OECD TG 201 (2011), GLP, RL 1: Based on solid content concentrations, the following effect values were obtained:
The EC50-values with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 464 (433 - > 472) mg solid content/L and 122 (97.2 - 158) mg solid content/L. The EC10-values with 95 % confidence intervals for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours were 110 (87.3 - 129) mg/L and 9.72 (< 4.72 - 18.0) mg solid content/L. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 14.9 mg solid content/L.

Additional information

The acute toxicity of the test item to fish (zebrafish) was determined according to the principles of the OECD-Guideline for Testing of Chemicals No. 203 (1992) and EU Council Regulation (EC) No. 440/2008/ Method C.1 (2008) from 2017-02-27 to 2017-03-17, with a definitive exposure phase from 2017-03-13 to 2017-03-17 at the test facility.

An acute toxicity test under semi-static conditions with daily renewal of the test media was conducted with the nominal test item concentrations of 13.3 - 26.5 - 53.0 - 106 - 212 mg/L (factor 2), corresponding to a nominal solid content of 6.28 – 12.5 – 25.0 – 50.0 – 100 mg/L. Duration of the test was 96 hours. Seven test organisms were exposed to each test concentration and the control. Water quality parameters (temperature, pH-value and oxygen-saturation) measured at 0, 24, 48, 72 and 96 hours were determined to be within the acceptable limits. The determination of the test concentrations was carried out via LC‑MS/MS. Evaluation was done from freshly prepared media after 0 and 72 hours and from the corresponding 24 hours aged test media after 24 and 96 hours. The measured concentrations in freshly prepared media were in the range of 85 and 102 % of the nominal values. In corresponding 24 hours aged test media, the measured concentrations were between 83 and 113 % of the nominal values. Therefore, all effect values are based on nominal

concentrations of the test item. All validity criteria of the test guideline were met. The results of the study are summarized in the table below.

LC-Values (3 – 96 hours) of the Test Item

Based on nominal concentrations of the test item and the solid content [mg/L]

Test duration [h]	Test item [mg/L]		Solid content [mg/L]
	LC50	Confidence interval	LC50	Confidence interval
3	> 212	n.a.	>100	n.a.
24	180	(106 – 212)	85.0	(50.0 – 100)
48	180	(106 – 212)	85.0	(50.0 – 100)
72	180	(106 – 212)	85.0	(50.0 – 100)
96	180	(106 – 212)	85.0	(50.0 – 100)
LC100= Lowest test item concentration with 100 % mortality after 96 h	> 212		> 100
LC0= Highest test item concentration with 0 % mortality after 96 h	53.0		25

 

A 21-day chronic toxicity of the test substance to Daphnia magna was investigated under semi-static conditions in a study conducted according to OECD guideline 211. No significant mortality was seen was seen in controls and in concentrations up to 6.25 mg/L; gradual mortality was seen in the higher concentrations (at day 21 20 % in 12.5 and 25 mg/L). 40 % mortality was seen at the highest test concentration of 50 mg/L. Chemical analysis showed that the test substance concentration was not stable at room temperature. The test concentrations were too low to be measured accurately, but semi-quantitative measurement showed a fast decrease of the initial concentration within three hours, with a plateau at 30 %. The area signal could be used as an indication of stability. Results are expressed as nominal concentrations, but the actual concentration of the original component is lower. As the test concentrations could not be accurately measured the actual concentrations cannot be calculated.

The reproductive output (per surviving parent) was increased in the test conditions when compared to controls, except for the highest test concentration where the number of offspring was slightly lower but not significantly different to controls. It is concluded that the substance has no significant impact on the reproduction output of Daphnia at the test concentrations.

The EC50 at 48 h exposure was 83 mg/L based on test material which refers to 38.8 mg/L based on active ingredient.

No NOEC/LOEC for reproductive effects can be established as higher test concentrations would cause a too high mortality. Chronic lethal effects were prominent with NOEC/LOEC = 25/50 mg/L.This refers to NOEC/LOEC = 11.7/23.4 mg/L based on active ingredient.

In a supporting study according to the publication by Develter and Lauryssen (2010), a NOEC of 11.3 mg/L was determined which is practically identical with the one derived from the guideline study. As the experimental procedure is not as precisely defined as in the guideline study, the NOEC of 11.7 mg/L as derived in the guideline study was considered relevant.

Both studies agree that the reproductive output per surviving parent was higher in the test conditions when compared to controls, thus a stimulating effect on reproduction of the test item was seen.

The toxicity of Sophorolipids, partially hydrolysed, to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016 Method C. The aim of the study was the determination of NOEC, LOEC, EC10- , EC20- and EC50-values of the growth rate and the yield over a period of 72 hours.

The study was conducted under static conditions with an initial cell density of 6839 cells/mL. A stock solution and four dilution levels out of the stock solution were tested in a geometrical series with a dilution factor of √10: 10.0 - 31.6 - 100 - 316 - 1000 mg/L, corresponding to 4.72 – 14.9 – 47.2 – 149 – 472 mg solid content/L. Three replicates were tested for each test item concentration and six replicates for the control. The environmental conditions were within the acceptable limits.

The test media were visually clear at the start and after 24 hours of the exposure. After 48 and 72 hours of the exposure the test media were concentration related turbid. Although care was taken to avoid the formation of foam during preparation a concentration related foam formation was observed in the test media throughout the test period.

The concentrations of the solid content of the test item were analytically verified via LC-MS/MS at the start (0 h) and at the end (72 h) of the exposure in all tested concentration levels and the control. The measured concentrations at the start of the exposure were in the range of 94 and 102 % of the nominal values. At the end of the exposure the measured concentrations of the test item were in the range of 84 to 105 %. The measured concentrations were all within ± 20 % of the nominal concentrations. This indicates that the test item concentrations were successfully maintained for the duration of the test.

The EC50-values with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 983 (918 - > 1000) mg test item/L and 258 (206 - 335) mg test item/L. The EC10-values with 95% confidence intervals for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours were 234 (185 - 274) mg test item /L and 20.6 (< 10.0 - 38.2) mg test item /L. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 31.6 mg test item/L.

Based on solid content concentrations, the following effect values were obtained: The EC50-values with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 464 (433 - > 472) mg solid content/L and 122 (97.2 - 158) mg solid content/L. The EC10-values with 95 % confidence intervals for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours were 110 (87.3 - 129) mg/L and 9.72 (< 4.72 - 18.0) mg solid content/L. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 14.9 mg solid content/L.

Based on reliable data determined with the target substance, the following parameters were used for assessment:

EC50 for freshwater algae: 464 mg/L based on active ingredient

NOEC for freshwater algae: 14.9 mg/L based on active ingredient

A toxicity to microorganisms study does not need to be conducted because in a biodegradation study according to OECD 301F, GLP, reliability 1, no inhibitory effects of the test item were observed in the toxicity control.

According to Guidance R.10, the tested concentration at which toxicity to the inoculum can be ruled out with sufficient reliability can be considered as a NOEC for the toxicity to STP microorganisms. Thus, 100 mg/L are considered as the NOEC.