1,8-naphthylenediamine

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with acceptable restrictions.

Qualifier:

according to guideline

Guideline:

other: Amtsblatt der EG L 133 Teil C: Biologische Abbaubarkeit: Prüfung der Atmungshemmung

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Principles of method if other than guideline:

A defined amount of activated sludge is mixed with synthetic medium and the rate of respiration measured. This respiration is compared with those measured in assays with different concentrations of the test substance. The sensitivity of the activated sludge used is checked with 3,5-dichlorophenol as reference substance.

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Direct weighings were prepared to given the different test item concentrations. The test item was added into Erlenmayer flasks (incubation vessels) to about 130 mL deionised water and was stirred before testing (equilibration phase).
For the reference compound a stock solution at a concentration of 500 mg/L was prepared by dissolving 250 mg 3,5-Dichlorophenol in 5 mL NaOH und diluting to 0.5 litre with deionised water. The pH was adjusted to pH 7 +/- 0.5 with HCl.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Typ: mixed population of aquatic microorganisms, laboratory facility that is operated mainly with municipal wastewater (southern Wupperverband).
- Preparation: none
- pH 7.3
- Test concentration of the activated sludge: 400 mg/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

no data

Test temperature:

18.2 - 19.2 °C (including all test concentrations, controls and reference substance)

pH:

7.1 - 7.3 (including all test concentrations, controls and reference substance)

Dissolved oxygen:

6.3 - 8.1 mg O2/L (at the beginning of the test for test item)
3.6 - 7.3 mg O2/L (at the end of the test for test item)
6.1 - 8.8 mg O2/L (at the beginning of the test for the reference compound)
3.7 - 8.4 mg O2/L (at the end of the test for the refernce compound)
5.8 and 5.9 mg O2/L (at the beginning of the test for the control)
3.0 and 3.2 mg O2/L (at the end of the test for the control)

Salinity:

no data

Nominal and measured concentrations:

- Test concentrations: 56, 100, 180, 320 and 560 mg/L (nominal)
- Reference compound: 2.5, 5, 10, 20 and 40 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 ml glass Erlenmayer flasks
- type of application: direct weighing
- Temperature: 20 +/- 2 °C
- stirring period before start incubation time: 15 h (equilibration phase)
- test parameter: respiration rate
- Two controls, one at test start and one at test end
- One physoco chemical oxygen consumption control with the highest concentration of test substance
- no replicates

Reference substance (positive control):

yes

Remarks:

(3,5-Dichlorophenol, Purity : 99 %, concentration (2.5, 5, 10, 20 and 40 mg/L)

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

196 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

EC50 of the reference substance 3,5-dichlorophenol is in the range 5 - 10 mg/L
Inhibition: at 2.5 mg/L 18.2 %, 5 mg/L 27.3 %, 10 mg/L 58.5 %, 20 mg/L 78.8 % and at 40 mg/L 87.9 %.

Concentrationof test item[mg/L]	Respiration rate[mg/L*h]	Abiotic O2-respiration[mg/L*h]	Respirationabiotic-O2[mg/L*h]	Inhibition[%]
56	24.9	0.0*	24.9	24.5
100	23.0	0.0*	23.0	30.3
180	19.5	0.0*	19.5	40.9
320	12.0	0.0*	12.0	63.6
560	6.9	0.0*	6.9	79.1
Control mean value	33.0
Control 1	32.4
Control 2	33.6
*  The abiotic 02-Respiration was determined at a concentration of the substance of 10000 mg / L. Since in this study no abiotic 02-Respiration was determined, and lower concentration of the substance will not cause 02-Respiration (derived values​​).

Validity criteria fulfilled:

yes

Conclusions:

1,8-napthylenediamine showed 40.9 % respiration inhibition of activated slugde and an EC50 of 196 mg/L was obtained. The effect value relates to nominal concentration, since no analytical montitoring was performed.

Executive summary:

In order to test the toxicity to microorganisms of the substance, activated slugde from predominantly domestic sewage plant was exposed to the test solution of five nominal concentrations of thr substance (56, 100, 180, 320 and 560 mg/L) , blank control solution and solution with positive reference substance for a period of 3 hours. Dissolved oxygen was recorded and respiration rate were calculated.

1,8-napthylenediamine showed 40.9 % respiration inhibition of activated slugde and an EC50 of 196 mg/L was obtained.

Description of key information

In order to test the toxicity to microorganisms of the substance, activated slugde from predominantly domestic sewage plant was exposed to the test solution of five nominal concentrations of the substance (56, 100, 180, 320 and 560 mg/L) , blank control solution and solution with positive reference substance for a period of 3 hours. Dissolved oxygen was recorded and respiration rate were calculated. The test item showed 40.9 % respiration inhibition of activated slugde and an EC50 of 196 mg/L was obtained. The effect value relates to nominal concentration, since no analytical montitoring was performed.

Key value for chemical safety assessment

EC50 for microorganisms:

196 mg/L