Di(tetraethylammonium)hexahydroxoplatinate(IV)

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:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany
- Preparation of inoculum for exposure: the sludge was sieved, left alone to settle and the supernatant was decanted. The sludge was washed one time with isotonic solution. A small amount of the sludge was weighed and dried. From this result a stock solution of activated sludge in tap water was prepared with a mixed liquor suspended solids level of about 1 – 4 g dry mass sludge/liter.
The sludge stock solution was fed with synthetic sewage feed and was incubated aerated overnight at 20 ± 2 °C in the dark. The amount of food applied was 25 mL/L. After this preincubation, the activated sludge was adjusted on a mixed liquor suspended solids level of about 2 – 4 g dry mass sludge/liter. From this sludge, an amount to achieve a mixed liquor suspended solids level in the test vessel of nominally 1.5 g/L was applied.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.5 - 21.5 °C

pH:

8.4 - 8.5

Nominal and measured concentrations:

Nominal concentrations: 62.5, 125, 250, 500 and 1000 mg Pt TEAH solution per liter

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 L Erlenmeyer flasks
- Material, size, headspace, fill volume: 500 mL
- Aeration: air flow 0.5 – 1 L/min
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 6 vessels containing only inoculum (3 replicates were measured at the beginning and 3 at the end of the test assay series.
- No. of vessels per positive control (replicates): 1
- Sludge concentration (weight of dry solids per volume): 3.8 g/L
- Nutrients provided for bacteria: synthetic sewagecontainin peptone 16.0 g, meats extract 11.0 g, urea 3.0 g, NaCl 0.7 g, CaCl2.2H2O 0.4 g, MgSO4.7H2O 0.2 g, K2HPO4 2.8 g and deionised water ad 1000 mL.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water, free from inhibitory concentrations of toxic substances (e.g. Cu2+ ions)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : the total microbial respiration rate (total oxygen uptake including heterotrophic and nitrification uptake) was investigated by measurement of the oxygen concentration over a period of 10 minutes or at least until an O2-content of 2.5 mg O2/L was reached 3 hours after start of incubation

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: A range finding test was conducted to check if any adverse effect occurs up to and including a nominal loading of 1000 mg/L (test concentrations 10, 100 and 1000 mg/L). The effect of the test item on the total microbial respiration rate was investigated. Inhibition was found to be greater than 20% at 1000 mg/L. Therefore, a dose-response test with five concentrations was applied as main test.
- Test concentrations: 62.5, 125, 250, 500 and 1000 mg/L test item (definite test)
- Results used to determine the conditions for the definitive study:significant inhibition was observed in the range finding study

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

145 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other:

Remarks:

95% Confidence Interval: 43 - 239 mg/L

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

Remarks on result:

other:

Remarks:

95% Confidence Interval: >1000 - >1000 mg/L

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

LOEC

Effect conc.:

500 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

The EC50 for the reference item was found to be 15.7 mg/L and is therefore within the accepted range of the OECD 209 guideline of 2 to 25 mg/L.

Reported statistics and error estimates:

A LOEC was calculated by using ANOVA followed by Step-down Jonckheere-Terpstra Test Procedure. For trend analysis, a Contrasts test (Monotonicity of Concentration/Response) for metric data was applied. Since the test results show a concentration-response relationship, they were statistically analysed to determine EC values together with 95% confidence intervals using Probit-analysis assuming log-normal distribution of the values a non-linear data analysis.
The evaluation of the concentration-effect-relationships and the calculations of effect concentrations were based on the nominal test item concentrations.
For statistical calculations, the computer program ToxRat Professional version 3.3.0 by ToxRat® Solutions GmbH was applied.

Mean respiration rate (mg O₂/(h*g dry mass)).

                  TI = Test item; SD = Standard deviation; CV = Coefficient of variance.

	Control	62.5 mg TI / L	125 mg TI / L	250 mg TI / L	500 mg TI / L	1000 mg TI / L
Mean	36.5	39.7	38.7	31.7	24.7	26.4
SD	8.7	8.6	10.0	6.0	3.2	2.1
CV	23.7	21.5	25.7	19.1	13.1	8.1

 

Mean inhibition (%) of the respiration rate by the test item.

                  TI = Test item; *: significant difference when compared with control (p < 0.05).

62.5 mg TI / L	125 mg TI / L	250 mg TI / L	500 mg TI / L	1000 mg TI / L
-8.9%	-6.0%	13.2%	32.3% *	27.7% *

 

Effect concentration values [mg/L] for respiration rate.

                  EC = Effect concentration where x % inhibition deviation occurred against control; CL = Confidence level.

Parameter	EC10		EC20		EC50	EC80	NOEC		LOEC
	[mg test item/L]
Value	145	396		>1000		>1000		250		500
95 %-CL	(43 – 239)	(241 – 573)		(>1000 – >1000)		(>1000 – >1000)		-		-

Validity criteria fulfilled:

yes

Conclusions:

A significant inhibition of bacterial respiration by Pt TEAH solution started at a concentration of 500 mg per liter nominal loading. The NOEC is 250 mg Pt TEAH solution per liter. The EC10 and EC50 of Pt TEAH solution is 145 mg/L (95% CL: 43 – 239 mg/L) and >1000 mg/L (95% CL: >1000 – >1000), respectively, based on nominal loading.

Executive summary:

An activated sludge respiration inhibition test was conducted with di(tetraethylammonium)hexahydroxoplatinate(IV). The study is reliable without restrictions, being GLP-compliant and having followed standard test guidelines (OECD 209 and EU Method C.11).

The test item was given to the synthetic sewage with a concentration of 62.5, 125, 250, 500 and 1000 mg Pt TEAH solution per liter. A positive control was used, and all validity criteria were met. Di(tetraethylammonium)hexahydroxoplatinate(IV) had a statistically significant effect on bacterial respiration. Starting at a loading of 500 mg/L, the test item inhibited the respiration of the inoculum significantly. The NOEC was found to be 250 mg test item per liter (nominal loading).The EC₁₀and EC₅₀of di(tetraethylammonium)hexahydroxoplatinate(IV) is 145 mg/L (95% CL: 43 – 239 mg/L) and >1000 mg/L (95% CL: >1000 – >1000), respectively, based on nominal loading.

Description of key information

A significant inhibition of bacterial respiration by di(tetraethylammonium)hexahydroxoplatinate(IV) started at a concentration of 500 mg per liter nominal loading. The NOEC is 250 mg test item per liter. The EC10 and EC50 of the test item is 145 mg/L (95% CL: 43 – 239 mg/L) and >1000 mg/L (95% CL: >1000 – >1000), respectively, based on nominal loading.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

An activated sludge respiration inhibition test was conducted with di(tetraethylammonium)hexahydroxoplatinate(IV). The study is reliable without restrictions, being GLP-compliant and having followed standard test guidelines (OECD 209 and EU Method C.11).

The test item was given to the synthetic sewage with a concentration of 62.5, 125, 250, 500 and 1000 mg Pt TEAH solution per liter. A positive control was used, and all validity criteria were met. Di(tetraethylammonium)hexahydroxoplatinate(IV) had a statistically significant effect on bacterial respiration. Starting at a loading of 500 mg/L, the test item inhibited the respiration of the inoculum significantly. The NOEC was found to be 250 mg test item per liter (nominal loading).The EC₁₀and EC₅₀of di(tetraethylammonium)hexahydroxoplatinate(IV) is 145 mg/L (95% CL: 43 – 239 mg/L) and >1000 mg/L (95% CL: >1000 – >1000), respectively, based on nominal loading.