Fatty acids, tall-oil, reaction products with boric acid (H3BO3) and diethanolamine

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:

From 1993-11-15 to 1994-07-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

acceptable restriction was that analytical measurements on the test material were not conducted.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Principles of method if other than guideline:

not applicable.

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

- Concentrations: 1, 10, 100, 1000, and 10000 ppm
- Sampling method: The sludge/microbial inoculum was exposed to the test material. To measure the rate of oxygen consumption for the activated sludge after exposure to the test materials a Model 51 Yellow Springs Instruments dissolved oxygen meter was used. The oxygen meter was fitted with a BOD bottle probe, with a standard sensitivity membrane and an external output to a Fisher Recordal strip chart recorder. To measure the consumption of oxygen, a sub-sample of the exposed sludge was placed in a clean BOD bottle, the change in oxygen concentration over time was measured with the YSI meter and probe, and the results were recorded on the strip chart recorder.
- Sample storage conditions before analysis: none

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: As the test material was considered insoluble, no stock solution was prepared and the material concentrations were 1, 10, 100, 1000, 10000. Thus for 1 mg/L, 0.0005 g was added to the test vessel; for 10 mg/L, 0.0050 g; for 100 mg/L 0.05 g; for 1000 mg/L 0.5 g; and for 10000 mg/L 5.0 g. Each vessel was set up at 15 min intervals.
- Eluate: The dilution water for this test was from the City of Franklin, Tennessee, water supply. The water was softened and dechlorinated prior to use.
- Differential loading: see above.
- Controls: After the last test material vessel was prepared, a vessel with no test material was prepared as a test control replicate.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): none

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Method of cultivation: Immediately upon arrival, the sludge was aerated with low-pressure, oil-free air. The activated sludge organisms were fed a synthtic sewage feed at a rate of 50 mL per liter.
- Preparation of inoculum for exposure: Triplicate 4-mL samples of the mixed sludge were dried at 100°C in a Fisherbrand drying oven, until a constant weight was achieved. Based on these results the sludge was diluted to produce a dry weight per unit volume concentration of 4 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

none

Hardness:

no data

Test temperature:

20 +/- 1°C

pH:

no data

Dissolved oxygen:

no data

Salinity:

not applicable

Nominal and measured concentrations:

nominal concentrations: 1, 10, 100, 1000, and 10000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: flint glass bottles
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 1 L
- Aeration: yes
- No. of organisms per vessel: no data
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Photoperiod: in the dark
- Light intensity: not applicable

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (97% pure)

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

none

Results with reference substance (positive control):

- Results with reference substance valid: yes
- Relevant effect levels: EC50(3h) = 16 mg/L, i.e. in the acceptable range of 5-30 mg/L.
- Other: none

Reported statistics and error estimates:

none

No other information.

Validity criteria fulfilled:

yes

Conclusions:

The respiration rates of the sludge-associated microbes exposed to the 5 nominal concentrations of test item were 36.9, 31.7, 31.8, 29.5, and 20.2 mg O2/L*hr respectively. The EC50 was calculated to be greater than 10,000 mg/L.

Executive summary:

Guideline: The potential impact of the substance on microbial metabolism, as represented by the consumption of oxygen, was investigated using the "Activated Sludge, Respiration Inhibition Test" as prescribed by OECD (1984) and detailed in WCC Protocol OECD 209 (Expanded Range Procedures).

Methods: The test was performed on February 15, 1994. The test duration was a 3-h exposure period to the test material followed by up to 10 minutes for the measurement of oxygen consumption. The study design was comprised of 5 nominal exposure concentrations: 1, 10, 100, 1000, and 10000 ppm; a duplicated control group; and an assessment of the sensitivity of the inoculum used in the test to a reference toxicant (3,5-dichlorophenol).

Results: The activated sludge respiration test with test item passed the quality control criteria for an acceptable test. The EC50 calculated for the reference toxicant was 16.2 mg/L, within the acceptable range of 5 to 30 mg/L. The 2 control replicates produced oxygen consumption rates within the required 15% of each other, 33.4 and 33.0 mg O2/L x hour. The respiration rates of the sludge-associated microbes exposed to the 5 nominal concentrations of the substance were 36.9, 31.7, 31.8, 29.5, and 20.2 mg O2/L*hr respectively. The EC50 was calculated to be greater than 10,000 mg/L.

Description of key information

The respiration rates of the sludge-associated microbes exposed to the 5 nominal concentrations of the substance were 36.9, 31.7, 31.8, 29.5, and 20.2 mg O2/L*hr respectively. The EC50 was calculated to be greater than 10,000 mg/L (OECD 209).

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

Additional information

Guideline: The potential impact of the substance on microbial metabolism, as represented by the consumption of oxygen, was investigated using the "Activated Sludge, Respiration Inhibition Test" as prescribed by OECD (1984) and detailed in WCC Protocol OECD 209 (Expanded Range Procedures).

Methods: The test was performed on February 15, 1994. The test duration was a 3-h exposure period to the test material followed by up to 10 minutes for the measurement of oxygen consumption. The study design was comprised of 5 nominal exposure concentrations: 1, 10, 100, 1000, and 10000 ppm; a duplicated control group; and an assessment of the sensitivity of the inoculum used in the test to a reference toxicant (3,5-dichlorophenol).

Results: The activated sludge respiration test with test item passed the quality control criteria for an acceptable test. The EC50 calculated for the reference toxicant was 16.2 mg/L, within the acceptable range of 5 to 30 mg/L. The 2 control replicates produced oxygen consumption rates within the required 15% of each other, 33.4 and 33.0 mg O2/L x hour. The respiration rates of the sludge-associated microbes exposed to the 5 nominal concentrations of the substance were 36.9, 31.7, 31.8, 29.5, and 20.2 mg O2/L*hr respectively. The EC50 was calculated to be greater than 10,000 mg/L.