Propargite

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20th June 1989 to 19th July 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: municipal sewage treatment plant, Waterschap de Aa, Schijndel, The Netherlands
- Pretreatment: aeration for 4.5 hours and then left to settle for two hours.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium (substance and final concentration in test solution (mg/L)): KH2PO4 17.2, K2HPO4 43.6, Na2HPO4.12H2O 134.4, NH4Cl 3.4, MgSO4.7H2O 22.5, CaCl2.2H2O 36.4, FeCl3 0.6 and (NH4)2SO4 40.

- Test temperature: 20 ± 2 ºC

TEST SYSTEM
- Culturing apparatus: 3 litres, 4 all-glass brown bottles
- Number of culture flasks/concentration: one
- Method used to create aerobic conditions: 30 mL of the inoculum was added to the test medium. This mixture was aerated with CO2-free air for 24 hours.
- Details of trap for CO2 and volatile organics if used: three CO2 absorber bottles containing 80 mL 0.025N Ba(OH)2 and connected in a series to the exit air line of each test bottle. The CO2 produced was precipitated out as barium carbonate; the amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05 N HCl. Titrations were made every other day for the first 10 days and thereafter every fifth until day 28.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

> 2 - < 5.9

Sampling time:

28 d

Results with reference substance:

74.4 % degradation over 28 days.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Under the conditions of the test, the test material is not considered to be readily biodegradable.

Executive summary:

Propargite technical was tested for its ready biodegradability in the modified Sturm Test at 10 and 20 mg/L. The relative degradation values calculated from the measurements performed during the test period revealed that propargite was not degraded significantly (<10 %) during the test period of 28 days. The positive control substance was degraded for more than 60 % within 12 days. Propargite therefore appeared to be not readily biodegradable under the conditions of the test.

Description of key information

The substance was determined to be not readily biodegradable; study conducted in accordance with OECD Guideline 301B (CO2 evolution test); Coenen (1989)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Propargite technical was tested for its ready biodegradability in the modified Sturm Test at 10 and 20 mg/L. The relative degradation values calculated from the measurements performed during the test period revealed that propargite was not degraded significantly (<10 %) during the test period of 28 days. The positive control substance was degraded for more than 60 % within 12 days. Propargite therefore appeared to be not readily biodegradable under the conditions of the test.