N,N,N',N'-tetramethylethylenediamine

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

OECD 301B toxicity control

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-10-05 to 2017-11-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

Principles of method if other than guideline:

The toxicity control of a reliable ready biodegradability study performed according to OECD guideline 301B has been used to assess the toxicity of TMEDA to activated sludge microorganisms.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identity: TMEDA, termed ATMEDAHP in the report
Purity: 99.9%
Lot number: 17F-1069978
C content: 62.01% (calculated)
Appearance: Clear to slightly hazy, pale yellow liquid

Analytical monitoring:

yes

Remarks:

Analysis to determine CO2 evolution

Details on sampling:

The CO2 produced in the reactors was absorbed in two 250 mL gas wash bottles in series each filled with 200 mL 0.2 M NaOH. Sampling was performed through the lateral connecting pieces through the butyl rubber septum using 5 mL PE syringes.

Vehicle:

no

Details on test solutions:

The toxicity control treatment exposed activated sludge to a concentration of 40 mg/L organic carbon, corresponding to 56.7 mg TMEDA/L.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The test inoculum was provided by a sample of activated sludge obtained from AZV Staufener Bucht, a municipal STP (140,000 population equivalent) that receives predominantly domestic wastewater. The sample was obtained on the day before the start of the study and washed in tap water and test medium prior to use. Activated sludge was applied at a concentration of 30 mg dry solids/L in each of the test vessels.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

28 d

Remarks on exposure duration:

Standard exposure duration for an OECD 301B ready biodegradability test

Hardness:

NA

Test temperature:

21.2 - 24.0 °C

pH:

Not specified

Dissolved oxygen:

NA

Salinity:

NA

Conductivity:

NA

Nominal and measured concentrations:

40 mg/L organic carbon, corresponding to 56.7 mg TMEDA/L.

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

56.7 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The degradation extent in the toxicity control was 38.8% within 14 days, but decreased in the further test duration to 33.1%, based on the combined ThCO2 yield of the test and reference items. This exceeds the 25% threshold value and according to the guideline the test substance therefore had no inhibitory effect on the inoculum. The apparent decrease in percentage biodegradation in the toxicity control during the second half of the incubation and the negative degradation value of the test item indicate that the test item had a slight effect on the inoculum that caused endogenous microbial respiration to be suppressed compared to that in the blank flasks.

Results with reference substance (positive control):

The reference compound sodium benzoate reached the pass level for ready biodegradability within 4 days

Biodegradation of TMEDA toxicity control under ready biodegradability (OECD 301B; CO2 Evolution) test conditions

Biodegradation: blank-corrected CO2 yield as % of theoretical
Day	Toxicity control
0	0
4	33.5
7	37.5
11	38.6
14	38.8
21	35.2
28	31.0
(29)^a	33.1

^a  Includes final purge of CO2 following acidification of test media and cessation of biological activity on D 28.

Validity criteria fulfilled:

yes

Conclusions:

The extend to degradation in the toxicity control was 38.8% within 14 days and 33.1% in the further test duration, based on the combined ThCO2 yield of the test and reference items. This exceeds the 25% threshold value, therefore according to the OECD 301B guideline TMEDA is concluded to have no inhibitory effect on the inoculum.

Executive summary:

The toxicity control treatment of the available OECD 301B ready biodegradability test for TMEDA (Flach, 2018) demonstrated that there was no toxicity to activated sludge microorganisms following exposure of 40 mg/L organic carbon (corresponding to 56.7 mg TMEDA/L). As such, a NOEC of 56.7 mg/L is concluded for microorganisms.  

Description of key information

The toxicity control treatment of the available OECD 301B ready biodegradability test for TMEDA (Flach, 2018) demonstrated that there was no toxicity to activated sludge microorganisms following exposure of 40 mg/L organic carbon (corresponding to 56.7 mg TMEDA/L). As such, a NOEC of 56.7 mg/L is concluded for microorganisms.  

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

56.7 mg/L