Monalazone disodium

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:

26.10.2018-

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD 301B

Version / remarks:

Toxicity control

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Test Item : Monalazone Disodium

Physical appearance : White or off white powder or crystals

Lot No. : 72617S

% Total Active Ingredient : >99% excluding water

Molecular formula : C7H4ClNNa2O4S

Molecular weight : 279.602 g/mol

Manufactured date : 26 July 2017

Expiry date : 01 February 2019

Recommended storage condition : Ambient (+18 to +36 °C)

pH : 8-10


Notes: a) Date of receipt of test item at test facility: 22 September 2018
b) Test Item code by test facility: H017-01

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

Stock Solutions

All chemicals were of either analytical or better grade reagents:

Stock Solution Chemical Quantity (g)
A Potassium dihydrogen orthophosphate, KH2PO4 (AR) 4.2516
Dipotassium hydrogen orthophosphate, K2HPO4 (AR) 10.8731
Disodium hydrogen orthophosphate dihydrate, Na2HPO4.2H2O (AR) 16.7017
Ammonium chloride, NH4Cl (AR) 0.2518
These four constituents were dissolved in and made up to 500 mL using Milli-Q water. The pH of the solution was 7.53
B
Calcium chloride, dihydrate, CaCl2.2H2O (AR) 18.2011
This was dissolved in and made up to 500 mL using Milli-Q water.
C
Magnesium sulphate heptahydrate, MgSO4.7H2O (ExcelaR) 11.2511
This was dissolved in and made up to 500 mL using Milli-Q water.

D Iron (III) chloride hexahydrate, FeCl3.6H2O (AR) 0.1256
This was dissolved in and made up to 500 mL using Milli-Q water.

The test medium for test flasks 1 to 6, was prepared by mixing 24 mL of stock solution A with 1920 mL of Milli-Q water, then 2.4 mL each of stock solutions B, C and D was added and finally the volume was made up to 2400 mL using Milli-Q water in each flask.

Similarly, for Flask 7, 3000 mL of test medium was prepared by mixing 30 mL of stock solution A with 2400 mL of Milli-Q water, then 3 mL each of stock solutions B, C and D was added and finally the volume was made up to 3000 mL with Milli-Q water.

The pH of the test medium was in the range of 7.51 to 7.55.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The inoculum was a secondary effluent, collected from a treatment plant receiving predominantly domestic sewage. This effluent was used as test system as it is recommended in the guideline. A fresh sample of secondary effluent was collected from the treatment plant and was kept aerobic during transport.

This effluent was allowed to settle for one hour, decanted and the decanted effluent was used in the test.

Source of the Inoculum

Sewage Treatment Plant
Eurofins Advinus Limited
Bengaluru – 560 058
India

Determination of Bacterial Population in the Inoculum

The bacterial population in the inoculum was determined as colony forming units (CFU/mL) by diluting the inoculum to an appropriate dilution and then plating on nutrient agar plates.

Preconditioning of the Inoculum

The decanted effluent was preconditioned by aerating for 5 days at 22 to 24C.
The bacterial population in the inoculum was 6.0 x 107 CFU/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

14 d

Hardness:

not specified

Test temperature:

22-24 C

pH:

7.81-7.87

Dissolved oxygen:

not specified

Salinity:

not specified

Conductivity:

not specified

Nominal and measured concentrations:

10-20 mg/L

Reference substance (positive control):

yes

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

20 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

• There was 38.63% degradation [based on ThCO2] in the toxicity control flask on day 13, which is in accordance with the guideline requirement that, in a toxicity test, containing both the test item and a reference item, if less than 25% ThCO2 occurs within 14 days, the test substance can be assumed to be inhibitory. This shows that the test item is not inhibitory to the test system.

Results with reference substance (positive control):

• There was 38.63% degradation [based on ThCO2] in the toxicity control flask on day 13, which is in accordance with the guideline requirement that, in a toxicity test, containing both the test item and a reference item, if less than 25% ThCO2 occurs within 14 days, the test substance can be assumed to be inhibitory. This shows that the test item is not inhibitory to the test system.

Validity criteria fulfilled:

yes

Conclusions:

in a toxicity test, containing both the test item and a reference item, if less than 25% ThCO2 occurs within 14 days, the test substance can be assumed to be inhibitory. This shows that the test item is not inhibitory to the test system.

Executive summary:

in a toxicity test, containing both the test item and a reference item, if less than 25% ThCO2 occurs within 14 days, the test substance can be assumed to be inhibitory. This shows that the test item is not inhibitory to the test system.

Description of key information

in a toxicity test, containing both the test item and a reference item, if less than 25% ThCO2 occurs within 14 days, the test substance can be assumed to be inhibitory. This shows that the test item is not inhibitory to the test system.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

20 mg/L