Decanoic acid, mixed esters with dipentaerythritol, heptanoic acid and octanoic acid.

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:

14 April 2004

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

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Since HATCOL 5127 was poorly soluble in water, the test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/1 was tested in duplicate.

Reference substance
A solution of 3,5-dichloraphenol was prepared by dissolving 125.8 mg in 2.5 ml 1 N NaOH, diluting it to approximately 7.5 ml with Milli-Q water and adding under stirring 1 N H2S04 to the paint of incipient precipitation. Finally the solution was diluted to 250 m1 with Milli-Q water. The pH was 8.0. Aliquots 50 ml were stored in a freezer until use. On the day of testing the reference substance solution was defrosted at room temperature.
Three concentrations were tested: 3.2, 10, 32 mg/l.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Test system: Micro-organisms in activated sludge.
Source: Municipal sewage treatment plant: Waterschap de Maaskant', 's-Hertogenbosch, the Netherlands, receiving predominantly domestic sewage.
Number of micro-organisms: Number of micro-organisms was determined as the amount of Mixed Liquor Suspended Solids (MLSS) per litre test medium.
Preparation of the sludge: The sludge was coarsely sieved, washed and diluted with tap-water. A small amount of the sludge was weighed and dried at ca. 105°C to determine the amount of suspended solids (2.6 g/l of sludge, as used for the test). The pH on the day of testing was 7 .9. The batch of sludge was used on the subsequent day, therefore 50 ml of synthetic sewage feed was added to each litre of activated sludge at the end of the day. The sludge was kept aerated at test temperature until use.
Rationale: Recognized by international guidelines as the recommended test system.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Hardness:

Not specified

Test temperature:

18.6 and 19.2°C

pH:

7.9

Dissolved oxygen:

Not specified

Salinity:

Not applicable.

Conductivity:

Not specified

Nominal and measured concentrations:

Norminal 100 mg/L

Details on test conditions:

Test procedure and conditions
Contact time: 30 minutes, during which aeration and stirring took place.
Vessels: AII glass, 300 ml oxygen bottles and 1 1 test bottle
Milli-RO / Milli-Q water: Tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon and ion­exchange ca􀅈ridges (Milll-Q) (Millipore Corp., Bedford, Mass., USA).
Synthetic sewage feed: 16 g peptone
11 g meat ex1ract
3 g urea
0.7g NaCI
0.4 g CaCl2.2H20
0.2 g MgS0,.7H20
2.Bg K,HPO,
Dissolved in Milli-Q water, made up to 1 1 and filtered. The pH was 7.0.
Air supply: Clean, oil-free air.
Oxygen meter: WTW inolab Oxi Level 2 supplied with a WTW CellOx 325 oxygen electrode, electrolyte type ELY/G.
Recorder: Flatbed recorder SE 102 (Kipp & Zonen).
Performance of the test:
The synthetic sewage feed (16 ml) and an adequate amount of the test substance were mixed and made up to 300 ml with Milli-RO water. Activated sludge (200 ml) was added to provide a final volume of 500 ml. The mixture was then aerated in a 11 bottle during the contact time, using a pipette as an aeration device.
Then a well mixed sample of the contents was poured into a 300 ml oxygen bottle, and the flask was sealed with an oxygen electrode connected to a recorder, forcing the air out of the vessel. Oxygen consumption was measured and recorded for at least 10 minutes. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer. The pH and temperature were determined in the remaining part of the reaction mixture. This procedure was repeated for the duplicate concentration. ln each test series two controls without test substance were tested, one at the start and one at the end.
Each batch of activated sludge was checked for sensitivity by testing the reference substance 3,5-dichlorophenol.

Reference substance (positive control):

yes

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

No inhibition of respiration rate of the sludge was recorded at 100 mg HATCOL 5127 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Experimental conditions: The temperature of the test medium was between 18.6 and 19.2°C.

Results with reference substance (positive control):

Reference substance was observed to inhibit the total respiration rate.

Controls (C) and HATCOL 5127 (T): pH, oxygen concentration, oxygen consumption and percentage inhibition

Flask	Concentration (mg/l)	Oxygen conc. at the start (mg o2/l)	Oxygen consumption mg/o2/l/hr	% inhibition	pH
C1	0	8.3	29	-	8.0
C2	0	8.5	31	-	7.9
Mean C1+C2			30 (7%)
T1	100	6.9	32	-7	7.9
T2	100	7.1	31	-3	7.8

Negative values indicate stimulation of respiration rate of the sludge. These values are considered as not significant.

Reference substance (R; 3, 5-dichlorophenol): pH, oxygen concentration, oxygen consumption and percentage inhibition

Flask	Concentration (mg/l)	Oxygen conc. at the start (mg o2/l)	Oxygen consumption mg/o2/l/hr	% inhibition	pH
R1	3.2	8.1	25	17	8.0
R2	10	8.2	15	50	7.9
R3	32	8.9	8	73	7.9

 

Determination of the EC50-value for 3,5-dichlorophenol

% inhibition

Concentration (mg/L)	X Log conc. (mg/L)	Y Inhibition (%)
3.2 10 32	0.505 1.000 1.505	17 50 73

Slope: 55.9637

Intercept: -9.489

Multiple R: 0.9941

N=number of observations: 3

Prediction of x values based on known y values

Known Y Inhibition (%)	10 xlog (mg/l)	10x95% (mg/l)	10x95% (mg/l)
50	11.6	0.8	157.8

 

Regression line: Y= 55.96 X -9.49

 

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this present test, HATCOL 5127 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/l.
This concentration was prepared by direct addition of HATCOL 5127 to the test vessels and exceeded the solubility of HATCOL 5127 in water.

Executive summary:

The influence of HATCOL 5127 on the respiration rate of activated sludge was investigated after a contact time of 30 minutes.

The study procedure was based on OECD Guideline No. 209, adopted April 4, 1984 and EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L133, adopted May 30, 1988.

HATCOL 5127 was a light yellow liquid.

Since HATCOL 5127 was poorly soluble in water, the test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/l was tested in duplicate.

No inhibition of respiration rate of the sludge was recorded at 100 mg HATCOL 5127 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion, under the conditions of this present test, HATCOL 5127 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/l.

Description of key information

Under the conditions of this present test, HATCOL 5127 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/l.

This concentration was prepared by direct addition of HATCOL 5127 to the test vessels and exceeded the solubility of HATCOL 5127 in water.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

The influence of HATCOL 5127 on the respiration rate of activated sludge was investigated after a contact time of 30 minutes.

The study procedure was based on OECD Guideline No. 209, adopted April 4, 1984 and EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L133, adopted May 30, 1988.

HATCOL 5127 was a light yellow liquid.

Since HATCOL 5127 was poorly soluble in water, the test substance was quantitatively added to the test vessels. A nominal concentration of 100 mg/l was tested in duplicate.

No inhibition of respiration rate of the sludge was recorded at 100 mg HATCOL 5127 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion, under the conditions of this present test, HATCOL 5127 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg/l.