Ammonium bromide

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:

2008

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

The oxygen measurement was made in each sample over a period of 10 minutes at the following time points: 0.25; 0.5; 0.75; 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.0; 4.5; 5.0; 5.5; 6.0; 6.5; 7.0; 7.5; 8.0; 8.5; 9.0; 9.5; 10 minutes.

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

- Laboratory culture: No
- Source: Domestic wastewater treatment plant
- Sampling site: Romanshorn, Switzerland
- Method of cultivation: Details are not provided.
- Preparation of inoculum for exposure: The activated sludge was washed three times by centrifugation (10 min at 1000 rpm) and re-suspended in tap water. The inoculum received synthetic sewage feed, was aerated overnight and used for testing the next day.
- Pretreatment: No further information is given.
- Initial cell concentration: 4.1g/L, being in the required range of 4.0 g/L ± 10%.

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.8 - 20.6°C

pH:

8.00 (pH of inoculum taken before start of exposure)

Nominal and measured concentrations:

0, 63, 125, 250, 500, 1000 mg ammonium bromide/L (nominal)

Details on test conditions:

TEST SYSTEM
- Culture medium: The synthetic sewage feed used, was prepared according to the guideline.
- Culturing apparatus: 1000 mL beaker were used for the contact time of 3 hours, afterwards, the suspensions were transferred to BOD-flasks
- No. of vessels per concentration (replicates): 1
- Suspended solids concentration: Nominal concentration in the inoculum solution 1.6 g/L
- Aeration device: Constant stirring with magnetic stirrers
- Measuring equipment: Oxygen electrode


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Analytical parameter: Oxygen measurement
- Test parameter: Respiration rate (Oxygen consumption)

CONTROLS
Two controls without TS were tested and additionally one abiotic control (named blank), which contained the highest concentration of the test substance, the synthetic sewage feed and water

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 739.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 1281.3 - 28567.1

Details on results:

Respiration rates and inhibition rates are given in table A7.4.1.4/02-4, please see "Remarks on results including tables and figures".
No other effects were observed.
Respiration rates of controls are given in table A7.4.1.4/02-4.

Results with reference substance (positive control):

- Concentrations: 5, 15, 30 mg 3,5-dichlorophenol/L
- Results: Respiration inhibition of 17.6, 54.8 and 70.5% were determined and an EC50 = 12.3 mg 3,5-dichlorophenol/L was calculated

Reported statistics and error estimates:

The EC50 and their 95% confidence intervals were calculated using probit analysis. The computer program used to run the statistical analyses was "SPSS for Windows”, release 11.0.1., 2001 by SPSS Inc.

Table A7.4.1.4/02-4:      Respiration and inhibition rates of ammonium bromide

Nominal concentration of TS/Reference Substance [mg/L]	Respiration rate [mg O2/L x h]	Inhibition   [%]	Time Interval used for Calculation [min]
Abiotic control^a	NR^b	NA^c	NA
Control A	54.9	NA	0.25 - 2.0
Control B	48.2	NA	0.25 - 4.0
Mean control (A + B)	51.5	NA	NA
3,5- Dichlorophenol	-	-	-
5.0	41.9	17.6	0.25 - 4.5
15	23.0	54.8	0.25 - 9.0
30	15.3	70.5	1.0 - 10.0
Ammonium bromide	-	-	-
63	71,5	-1.6	0.25 - 4.0
125	51,7	-1.7	0.25 - 3.0
250	55,2	-8.5	0.25 - 2.0
500	50,7	0.3	0.25 - 2.0
1000	46,9	7.8	0.25 - 4.0

a            abiotic control = highest test substance concentration, synthetic sewage and water

b                NR = not reported

c                NA = not applicable

Validity criteria fulfilled:

yes

Remarks:

The control respiration rates are within 15 per cent of each other; The EC50 (3 hours) of 3,5-dichlorophenol is in the accepted range 5 to 30 mg/L.

Conclusions:

The validity criteria required by the OECD Guideline No. 209 can be considered as fulfilled.
The EC50 (3h) > 1000 mg/L. The test material is not inhibitory to sewage sludge microorganisms.

Executive summary:

Materials and methods

The test was conducted according to OECD Guideline No 209. Activated sludge from a domestic waste water treatment plant was used.

Results and discussion

The respiration rates measured at 63, 125, 250, 500 and 1000 mg ammonium bromide/L were 51.7, 51.7, 55.2, 50.7 and 46.9 mg O2/[L x h], respectively. This corresponds to respiration inhibitions by the test item of -1.6, -1.7, -8.5, 0.3 and 7.8%.

E20 (95% C.I.) = 1272.7 mg ammonium bromide/L (1006.6 - 13680.2)

E50 (95% C.I.) = 1739.4 mg ammonium bromide/L (1281.3 - 28567.1)

E80 (95% C.I.) = 2206.0 mg ammonium bromide/L (1529.7 - 43480.5)

Description of key information

Ammonium bromide is not inhibitory to sewage sludge microorganisms (EC50 > 1000 mg/L)

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

In a key study conducted according to OECD Guideline No 209. Activated sludge from a domestic waste water treatment plant was used.

The respiration rates measured at 63, 125, 250, 500 and 1000 mg ammonium bromide/L were 51.7, 51.7, 55.2, 50.7 and 46.9 mg O2/[L x h], respectively. This corresponds to respiration inhibitions by the test item of -1.6, -1.7, -8.5, 0.3 and 7.8%.

E20 (95% C.I.) = 1272.7 mg ammonium bromide/L (1006.6 - 13680.2)

E50 (95% C.I.) = 1739.4 mg ammonium bromide/L (1281.3 - 28567.1)

E80 (95% C.I.) = 2206.0 mg ammonium bromide/L (1529.7 - 43480.5)