Pyrogallol

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

Principles of method if other than guideline:

Commission Regulation (EC) No 440/2008

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Concentration of the activated sludge was 1000 mg/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20-22° C

pH:

8.3

Dissolved oxygen:

Oxygen consumption rate 0.5 mg/L min

Nominal and measured concentrations:

1000 mg/L

Details on test conditions:

The tested concentration of pyrogallol was set at limit concentration of 1000 mg/L in triplicate along with blank control. The system was aerated and stirred during the test.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Validity criteria fulfilled:

yes

Conclusions:

The EC50 and NOEC (No Observed Effect Concentration) values for total respiration inhibition and heterotrophic respiration inhibition of pyrogallol were determined to be higher than 1000 mg/L, respectively.

Executive summary:

The toxic effect of Pyrogallol\ Pyrogallic acid on micro-organisms from activated sludge (largely bacteria) was studied. The tested concentration of Pyrogallol\ Pyrogallic acid was set at limit concentration of 1000 mg/L in triplicate along with blank control (without test item) and reference substance (3,5-Dichlorophenol) concentrations at 2, 8 and 32 mg/L in two sets. One set of all test groups was used to determine total respiration and another set of all test groups added with N-allylthiourea at 11.6 mg/L was used to determine nitrification potential of sludge.  

Test item mixtures and reference substance mixtures were prepared by adding required quantity of test item and reference substance directly into the test vessels to obtain different nominal concentrations, respectively. Blank control, test mixtures and reference substance mixtures were aerated for 3 h at 20.8-21.9^oC. The oxygen consumption rate in the mixture was measured for 10 minutes using dissolved oxygen electrode and the respiration rate was calculated.

No significant inhibition of Pyrogallol\ Pyrogallic acid was observed in both total respiration and heterotrophic respiration. The nitrification respiration rate was found to be not significant (significance was 0.71%) hence the inhibition of Pyrogallol\ Pyrogallic acid due to nitrification respiration was not calculated.

Therefore, the EC₅₀and NOEC (No Observed Effect Concentration) value for total respiration inhibition and heterotrophic respiration inhibition of Pyrogallol\ Pyrogallic acid are higher than 1000 mg/L, respectively.

The calculated per cent inhibition, total respiration of reference substance, 3,5-Dichlorophenol was 39.90, 63.60 and 95.70 % and heterotrophic respiration was 25.8, 60.30 and 95.30 % at the tested concentrations of 2, 8 and 32 mg/L, respectively.

The EC₅₀value of 3,5-Dichlorophenol, total respiration inhibition and heterotrophic respiration inhibition is 3.57 and 5.04 mg/L, respectively.

Description of key information

The EC₅₀and NOEC (No Observed Effect Concentration) values for total respiration inhibition and heterotrophic respiration inhibition of pyrogallol were detrminated to be higher than 1000 mg/L, respectively

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L