Sorbitan, tridocosanoate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data based on the inhibition control of a ready biodegradability study. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2012).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Toxicity control: In one test vessel, 30 mg of the test sample and 30 mg of sodium benzoate were accurately weighed with an electronic analytical balance and added to the mineral medium [the volume
subtracting the volume (4.00 mL) of activated sludge from 300 mL], so that each concentration of the test item and sodium benzoate reaches 100 mg/L.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge obtained from site Kurume central sewage treatment center (Kurume-shi, Fukuoka, Japan), receiving predominantly domestic sewage
- Concentration of sludge: 30 mg/L (suspended solids)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Details on test conditions:

TEST CONDITIONS
- Composition of medium: mineral medium according to guidelne
- Test temperature: 22±1 °C
- Continuous darkness: yes
- pH: 7.3 - 7.8 (at the end of exposure)
- Other: Test solutions were stirred continuously.

TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus (No. CM-067)
- Number of culture flasks/concentration: 2
- Details of trap for CO2 and volatile organics if used: Soda lime No.1 (for absorption of carbon dioxide, Wako Pure Chemical Industries)
SAMPLING
- Sampling frequency: O2 consumption was measured continuously.
- Sampling method: automatic measurement without specific sampling

Reference substance (positive control):

yes

Remarks:

benzoic acid, sodium salt

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Result of toxicity control from ready biodegradability test

Results with reference substance (positive control):

The reference material (sodium benzoate) attained 99% degradation after 14 days

The toxicity control attained 34% degradation after 14 days of incubation.

 “If in  a toxicity test, containing both the test and reference substance, less than 35% degradation (based on total DOC) or less than 25% (based on total ThOD or ThCO2) occurred within 14 days, the test substance can be assumed to be inhibitory.”(OECD guideline 301)

Since more than 25% degradation occurred in the toxicity control, the substance is with high probability not toxic to aquatic microorganisms. The test item concentration in the toxicity control of 100 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

 

Description of key information

NOEC (14 d): 100 mg/L (inhibition control, OECD 301F)

Additional information

Experimental studies investigating the toxicity of the substance to aquatic microorganisms are not available. Therefore, the inhibition control of the available study on ready biodegradability was used to assess the toxicity to microorganisms. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017). Substances can be assessed as not inhibitory to aquatic microorganisms, if a biodegradation rate of > 25% based on oxygen demand (BOD/ThOD) is reached within 14 days in the inhibition control of a ready biodegradation test (OECD guideline 301). In the available ready biodegradation test on Sorbitan tridocosanoate, following OECD guideline 301F, the inhibition control contained 100 mg/L of the test sample and of sodium benzoate, respectively. A degradation rate of 34% based on O2 consumption was determined after 14 days of incubation. The reported results indicate no inhibitory effects of the substance on aquatic microorganisms and the test item concentration of 100 mg/L is used as NOEC.