α-n-butyl-α-(4-chlorophenyl)-1H-1,2,4-triazole-1-propanenitrile

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:

1988-12-07 to 1989-01-31

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

COD/BOD study preformed with 28 day biological phase. Results show limited solubility, study appears to be valid and shows that the substance is not readily biodegradable.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

The solution was inoculated with a number of micro-organisms (10E3 to 10E6 bacteria/mL final volume) from a mixed population from a strongly aerated activated sludge plant, and kept in closed bottles in the dark at 20ºC.

Duration of test (contact time):

28 d

Initial conc.:

ca. 2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Reference substance:

acetic acid, sodium salt

Remarks:

concentration of 2 mg/L

Key result

Parameter:

% degradation (DOC removal)

Value:

ca. 22.4

Sampling time:

28 d

Details on results:

Inhibition study shows absence of inhibition.

Key result

Parameter:

BOD5

Value:

0.39 other: mg O2/mg

Key result

Parameter:

COD

Value:

1.74 other: mg O2/mg

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Remarks:

The biodegradability of myclobutanil was 7.8, 13.5 and 22.4% at 5, 15 and 28 days, respectively. Although these results indicate inherent biodegradability, myclobutanil cannot be classified as readily biodegradable. This is compared to a biodegradability of >60% for the sodium acetate reference substance at 28 days.

Conclusions:

Myclobutanil shows inherent biodegradation but is not readily biodegradable under the conditions of the test.
Myclobutanil does not display inhibitory effects under the conditions of the test.

Executive summary:

Biodegradability of the test item was preformed as the biochemical oxygen demand (BOD) within 28 days as a percentage of the chemical oxygen demand (COD). Study was done broadly in accordance with EC Method C.6 and OECD guideline number 301D. The biodegradability of myclobutanil was 7.8, 13.5 and 22.4% at 5, 15 and 28 days, respectively.  Although these results indicate inherent biodegradability, myclobutanil cannot be classified as readily biodegradable.

Description of key information

Biodegradability of the test item was performed as the biochemical oxygen demand (BOD) within 28 days as a percentage of the chemical oxygen demand (COD). Study was done broadly in accordance with EC Method C.6 and OECD guideline number 301D. The biodegradability of myclobutanil was 7.8, 13.5 and 22.4% at 5, 15 and 28 days, respectively.  Although these results indicate inherent biodegradability, myclobutanil cannot be classified as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Type of water:

freshwater