2-Amino-3-bromopyridine

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jun 2016 - Feb 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3-bromopyridin-2-amine

EC Number:

629-620-5

Cas Number:

13534-99-1

Molecular formula:

C5 H5 Br N2

IUPAC Name:

3-bromopyridin-2-amine

Test material form:

solid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

After the 3-hour contact time, the oxygen consumption was recorded for a period of approximately 10 minutes. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer.
The pH was determined in the remaining part of the reaction mixture. This procedure was repeated for all test/reference item concentrations and controls.
The medium temperature was recorded continuously in a temperature control vessel(s). The temperature control vessel(s) was/were identically prepared compared to the control vessels. A temperature control vessel with a REES sensor was placed in each fume cupboard of the climate room.
Determination of oxygen was performed with multiple oxygen probes connected to a BlueBox (GO-Systemelektronik GmbH, Germany), a multichannel measuring and controlling system.

Test solutions

Vehicle:

yes

Details on test solutions:

Adjusted ISO-medium, formulated using RO water (tap water purified by reverse osmosis; GEON Waterbehandeling, Berkel- Enschot, The Netherlands) with the following composition:
CaCl2.2H2O 211.5 mg/L
MgSO4.7H2O 88.8 mg/L
NaHCO3 46.7 mg/L
KCl 4.2 mg/L

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

The sludge was coarsely sieved (1 mm) and allowed to settle. The supernatant was removed and ISO-medium was added. A small amount of the sludge was weighed and dried overnight at ca. 105°C to determine the amount of suspended solids (3.0 g/L of sludge, as used for the test). The pH was 7.7 on the day of testing. The batch of sludge was used one day after collection;
therefore 50 mL of synthetic medium was added per litre of activated sludge at the end of the collection day. The sludge was kept aerated at test temperature until use.

Study design

Test type:

not specified

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test conditions

Test temperature:

between 20 and 24°C

pH:

Before addition of sludge was between 7.2 and 7.5.
After the 3 hour exposure period the pH was between 7.8 and 8.4

Details on test conditions:

The pH in all test vessels, before addition of sludge was between 7.2 and 7.5. After the 3 hour
exposure period the pH was between 7.8 and 8.4.
The temperature continuously measured in the temperature control vessels ranged between 20
and 24°C during the test and was outside the range prescribed by the study plan.

Range-finding test: The temperature was not within the range described in the study plan (20±2 °C).
The temperature range was 19-23°C, except for a period of approximately 1 hour during the last run (1 hour during exposure and oxygen determination of controls 3-6). During this period the temperature was between 17 and 21°C.
Evaluation: The validity criteria for the controls and reference item were met and therefore this deviation has no effect on the study.

Final Test: The temperature was above the range prescribed by the study plan (20 ± 2°C) during the exposure phase, the temperature was 20-24°C.
Evaluation: The validity criteria for the controls and reference item were met and therefore this deviation has no effect on the study.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

0.8 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 2

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

89 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Effect concentrations 3

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this present test QAW039-C1 was not toxic to waste water bacteria
(activated sludge) at or below a loading rate of 3.2 mg/L (NOEC).
The EC10 was at a loading rate of 0.8 mg/L (95% confidence interval: 0.1 – 2.8 mg/L).
The EC20 was at a loading rate of 4.1 mg/L (95% confidence interval: 0.9 – 9.9 mg/L).
The EC50 was at a loading rate of 89 mg/L (95% confidence interval: 46 – 190 mg/L).