Reaction mass of N-(hydroxymethyl)hexadecan-1-amide and N-(hydroxymethyl)stearamide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05.09.17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Version / remarks:

22.07.10

Deviations:

yes

Remarks:

All measurement periods were less than 5 minutes. Because linearity of all regression curves was given and the correlation of the inhibition values within the test replicates was good, this was stated as uncritical.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on inoculum:

- Laboratory culture:
- Name and location of sewage treatment plant where inoculum was collected: sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant in D-67435 NW-Lachen-Speyerdorf.
- Method of cultivation:
- Preparation of inoculum for exposure:
- Pretreatment: filtrated, washed with tap water 3 times and re-suspended in tap water. The activated sludge was aerated until usage in the test and fed daily with 50 mL synthetic sewage feed /L.
- Initial biomass concentration: 2.06 g suspended solids/L dw, respectively, 1.03 g suspended solids/L dw for the test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

0.83 mmol

Test temperature:

20.7 - 21.6 °C

pH:

8.16

Conductivity:

228 µS/cm (25 °C)

Nominal and measured concentrations:

1000, 100. 10. 1 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: beakers
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: glass, 500 mL
- Aeration: purified air, using Pasteur pipettes, flow approx. 0.75 L/min
- Type of flow-through (e.g. peristaltic or proportional diluter): -
- Renewal rate of test solution (frequency/flow rate): -
- No. of organisms per vessel: 250 mL inoculum
- No. of vessels per concentration (replicates): positive control & lowest test concentration: one replicate, five replicates (highest concentrations);
- No. of vessels per control (replicates): two replicates before and two after measuring positive control and test item, respectively
- No. of vessels per vehicle control (replicates): -
- Biomass loading rate:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water
- Total organic carbon: < 0.5 mg/l
- Particulate matter:
- Metals:< 0.007 mg/L
- Pesticides: < LOD
- Chlorine: 12 mg/L
- Alkalinity: not stated
- Ca/mg ratio: 8
- Conductivity: 228 µS/cm
- Culture medium different from test medium:
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH: -
- Photoperiod: -
- Light intensity: -

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : inhibition of respiration rate

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:1000, 100, 10, 1 mg/L (nominal)
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

yes

Remarks:

3,5-DCP (CAS# 591-35-5)

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

EC50 = 12 mg/L (95 % c.i. 7.9 - 16 mg/L)

Validity criteria fulfilled:

yes

Conclusions:

Under test conditions no toxic effect was observed at the highest concentration of 1000 mg/L.

Executive summary:

One valid experiment was performed.

 

The test item was tested using 4 concentrations ranging from 1000 to 1 mg/L nominal concentration. Duration of the test was 3 hours. Activated sludge was used as inoculum. It was taken from a domestic sewage treatment plant and washed before usage. The dry matter was determined as 2.06 g suspended solids/L, giving a concentration of 1.03 g suspended solids/L in the test.

3, 5-Dichlorophenol was used as positive control. Four concentrations were tested; an EC50 of 12 mg/L (95 % confidence interval: 7.9 – 16 mg/L) was determined, which lies within the recommended range of 2 – 25 mg/L stated in the OECD guideline.

Because no significant inhibition was observed, no additional experiment had to be performed.

 

The following results for the test itemN-(hydroxymethyl) stearamidewere determined:

 

3h NOEC≥1000 mg/L

3h EC10>1000 mg/L

3h EC50>1000 mg/L

Description of key information

Based on the available OECD 209 study showing no significant effect at the highest concentration, the highest test concentration is selected for the further assessment as very conservative value.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L