Diamminedichloropalladium

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-compliant, guideline study available as an unpublished report. No restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant D-67435 NW-Lachen-Speyerdorf and aerated during transport. Upon arrival at the test facility the sludge was filtered, washed with tap water and resuspended in tap water. The activated sludge was aerated until usage and fed daily with 50mL/L synthetic sewage feed.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

1.08 mmol/L

Test temperature:

Pre-test: 19.1 - 20.8°C
Main study: 19.7 - 20.8°C

pH:

Pre-test: 6.25 - 8.25 at end of test
Main study: 7.6 - 8.0 at end of test

Dissolved oxygen:

Not reported

Salinity:

Not relevant

Nominal and measured concentrations:

Pre-test: Nominal Control, 1, 10, 100 and 100 mg/L
Main study: Nominal Control, 10, 20, 30, 60, 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Beaker
- Material, size, headspace, fill volume: Glass containing 500 mL test solution, nutrient solution and inoculum
- Aeration: purified air through pasteur pipette at 0.75L/min flow rate
- No. of vessels per concentration (replicates): Pre-test: 1 per test item concentration except highest contentration (5 replicates); Main study: 5 per test item concentration
- No. of vessels per control (replicates): Pre-test: 6 Control, 4 positive control; Main study: 6 Control, 4 positive control
- Biomass loading rate: Pre-test: 1.08g suspended solids/L; Main-study: 1.35 g suspended solids/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : oxygen consumption

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Range finding study: yes
- Test concentrations: 0, 10, 100, 1000 mg/L
- Results used to determine the conditions for the definitive study: -4.2% inhibition at 1 mg/L, -0.6% inhibition at 10 mg/L, 81.7% inhibition at 100 mg/L, 100% inhibition at 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

29 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL 28 - 30 mg/L

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

61 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL 59 - 63 mg/L

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

Diamminedichloropalladium

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

3-hour EC50 8.8 mg/L (95% CL 5.0 - 13 mg/L) which lies within the recommended range of 2- 25 mg/L.

Reported statistics and error estimates:

Oxygen consumption was calculated using linear regression.
EC50 was calculated using linear fit on a probability-logarithmic scale using Origin™ software.
NOEC was determined by testing equality of variance using and t-test or WEIR test.

Validity criteria fulfilled:

yes

Conclusions:

The 3-hour EC10 is 29 mg DDP/L (95% CL 28 - 30 mg/L). The 3-hour EC50 is 61 mg DDP/L (95% CL 59 - 63 mg/L). The NOEC is 18 mg DDP/L. This corresponds to 14.6 µg Pd L-1, 30.7 µg Pd L-1 and 9.1 µg Pd L-1, respectively.

Executive summary:

A GLP compliant, OECD guideline study to assess the inhibition of respiration of activated sludge was carried out (LAUS 2012). The study is considered to be suitable for use as the key study for this endpoint.

Description of key information

The EC50, EC10 and NOEC were determined to be 61 µg test item L-1, 29 µg test item L-1 and 18 µg test item L-1, respectively.

Additional information

An activated sludge respiration inhibition test was conducted with diamminedichloropalladium and the EC50, EC10 and NOEC were determined to be 61 µg test item L^-1 (30.7 µg Pd L^-1), 29 µg test item L^-1 (14.6 µg Pd L^-1) and 18 µg test item L^-1(9.1 µg Pd L^-1), respectively (Muckle 2012). The result was determined in a study following OECD guideline 209, with five test concentrations and a positive control included.