cyproconazole (ISO); (2RS,3RS;2RS,3SR)-2-(4-chlorophenyl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

23 Jan1996 to 13 Feb 1996

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

No guideline followed; not in accordance with GLP; not specified the position of the radiolabel

Qualifier:

no guideline followed

Principles of method if other than guideline:

14C-labelled test substance exposed to pure bacterial and fungal cultures and to activated sludge was investigated under aerobic static conditions for 21 days in the dark.

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

a) Arthrobacter sp. DSM 20407
b) Phanerochaete chrysosporium DSM 1556
c) Activated sludge from the aeration tank of a biological waste water treatment plant, not adapted, not pre-conditioned

Duration of test (contact time):

21 d

Initial conc.:

0.28 mg/L

Based on:

act. ingr.

Remarks:

in the presence of 2000 mg/I toluene

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITION
- Concentration
Pure cultures: 1 % inoculum from a pregrown culture
Activated sludge: 0.1 g/L dry matter in the final mixture
- Additional substrate: To half of the tubes 4-CL benzoate was added to serve as a potential enzyme inducer

- Source
Pure cultures: Lyophylisate from DSM, D-37073 Göttingen. Germany
Activated sludge: ARA Werdhölzli, CH-8048 Zürich (23.01.96; 8.30 a.m.)

- Illumination: Temperature-controlled dark room
- Temperature: 22 ± 0.5 °C

TEST SYSTEM
- Test unit: 125 mL closed glass bottle containing a total volume of test solution of 10 mL
- Test media: Prepared as indicated in Table 1 in 'Any other information on materials and methods incl. tables' with double distilled water (conductivity: < 1.5 μSi/cm; DOC: < 0.3 mg/L)

TEST PROCEDURE
- Handling: A glass tube containing 2 mL of 2 M KOH was placed within each serum bottle to trap potentially released CO2. The test bottles were incubated for 21 days in the dark and shaken carefully once a day to resuspend the sedimented microorganisms into the test medium. In a pretest it was assured by GC analysis that the headspace in the culture bottles contained enough oxygen for the used inocula during the whole test period.
The following additional test controls were investigated together with the test series:
a) Positive control with microorganisms in the presence of the same amount of toluene (20 μL/10 mL of final test volume) as added together with the radioactive test substance but without test substance
b) Blank with test substance/toluene but without microorganisms
c) Toxicity control with microorganisms and non-radioactive substance/toluene to check a potential toxicity of the test substance on the microorganisms

Reference substance:

other: No reference substance

Test performance:

All 3 examined microbial inoculum showed normal growth as confirmed by the positive and toxicity controls.

Key result

Parameter:

% degradation (radiochem. meas.)

Value:

0.7

Sampling time:

21 d

Remarks on result:

other: Activated sludge as microbial inoculum condition

Details on results:

Based on the data of the individual [14C] determinations a significant but low transformation of the test substance between 0.5 and 0.7 % of the initially added labelled test substance was observed only in the replicates which contained activated sludge as microbial inoculum. In all other replicates with the pure bacterial and fungal inoculum no significant release of [14CO2] was observed whereas the measured figures of 50 - 60 dpm were background values resulting from the addition of KOH into the scintillation cocktail.
All 3 examined microbial inoculum showed normal growth as confirmed by the positive and toxicity controls. No abiotic release of [14] into the KOH was observed as confirmed by the 2 blanks. Unexpectedly, no transformation activity was found with the white rot fungi Phanerochaete chrysosporium which exhibits an especially wide range degradation capability for recalcitrant compounds. In none of the tested biological systems 4-chlorobenzoate could serve as a potential enzyme inducer. Moreover, in the 2 replicates which contained 4-chlorobenzoate as a potential enzyme inducer an about 40 % lower transformation activity (e.g. [14CO2]-release) was found.

Remarks on result:

not measured/tested

Table 2. Test set up and [14C] at the end of the test in the individual test suspensions and in the corresponding KOH trapping solution.

No	Test unit	Inoculum	4-CI- benzoate	[14C] dpm a) test susp.	[14] dpm a) KOH
1	1. replicate	Arthrobacter sp.	+	76278	54
2	2. replicate	Arthrobacter sp.	+	85870	57
3	1. replicate	Activated sludge	+	76535	351
4	2. replicate	Activated sludge	+	74983	378
5	1. replicate	Arthrobacter so.	-	82829	49
6	2. replicate	Arthrobacter so.	-	84798	52
7	1. replicate	Activated sludge	-	125271	643
8	2. replicate	Activated sludge	-	79839	514
9	1. replicate	Ph. chrysosporium	+	67882	54
10	2. replicate	Ph. chrysosporium	+	80509	86
11	1. replicate	Ph. chrysosporium	+	79967	57
12	2. replicate	Ph. chrysosporium	+	79099	61
13	1. replicate	Ph. chrysosporium	-	84387	63
14	2. replicate	Ph. chrysosporium	-	83450	60
15	1. replicate	Ph. chrysosporium	-	83833	49
16	2. replicate	Ph. chrysosporium	-	79877	172
17	Positive control b)	Arthrobacter sp.	+	17	61
18	Positive control b)	Arthrobacter sp.	+	15	48
19	Positive control b)	Ph. chrysosporium	+	16	45
20	Blank	-	-	86922	41
21	Blank	-	-	75546	42
22	Toxicity control l. repl.	Ph. chrysosporium	-	15	61
23	Toxicity control 2. repl.	Ph. chrysosporium	-	16	51

a) dpm = desintegrations per minute

b) Contained no test substance

Validity criteria fulfilled:

no

Remarks:

Not specified

Interpretation of results:

not readily biodegradable

Conclusions:

Test substance does not appear to be readily biodegradable under the test conditions.

Executive summary:

The biological degradability of the 14C-labelled test substance exposed to pure bacterial and fungal cultures and to activated sludge was investigated under aerobic static conditions. The concentration of the test substance utilized in the test medium was 0.28 mg substance/L in the presence of 2 g/L toluene. The following additional test controls were investigated together with the test series:

1. Positive control with microorganisms and toluene but without test substance

2. Blank (abiotic) with test substance/toluene but without microorganisms.

3. Toxicity control with microorganisms and non-radioactive substance/toluene.

125mL gas-tight serum bottles (with 10 mL test suspension) were incubated for 21 days in the dark at 22 ± 0.5 °C. The incubation vessel was shaken carefully once a day to resuspend the sedimented microorganisms into the test medium. At the end of the incubation period the remaining radioactivity of the individual test suspensions as well as that released as 14CO2 and trapped in KOH solutions were determined using liquid scintillation counting.

The results showed that significant but low transformation of the test substance (0.5- 0.7 % of the initial level) was observed only in the replicates which contained activated sludge as microbial inoculum. In all other replicates with the pure bacterial and fungal inocula, no significant release of [14CO2] was observed. All 3 examined microbial inocula showed normal growth and no abiotic release of [14C] into the KOH. No transformation activity was found with the white rot fungi, Phanerochaete chrysosporium, which exhibits an especially wide range degradation capability for recalcitrant compounds. 4-chlorobenzoate could not serve as a potential enzyme inducer in any of the tested biological systems. Based on the findings, it was concluded that under the test conditions employed, the test substance does not appear to be readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Supplementary estimation of ready biodegradability using BIOWIN v4.10

Principles of method if other than guideline:

BIOWIN v4.10 prediction for readily biodegradation.

GLP compliance:

no

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

Biowin2 (Non-Linear Model)

Value:

0.008

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks:

Biowin1 (Linear Model)

Value:

0.242

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Endpoint	Result
Biowin1 (Linear Model Prediction)	Does Not Biodegrade Fast
Biowin2 (Non-Linear Model Prediction)	Does Not Biodegrade Fast
Biowin3 (Ultimate Biodegradation Timeframe)	Months
Biowin4 (Primary Biodegradation Timeframe)	Weeks
Biowin5 (MITI Linear Model Prediction)	Does Not Biodegrade Fast
Biowin6 (MITI Non-Linear Model Prediction)	Does Not Biodegrade Fast
Biowin7 (Anaerobic Model Prediction)	Does Not Biodegrade Fast
Ready Biodegradability Prediction	NO

The full results report is attached to this IUCLID record

Description of key information

The substance is treated to be not readily biodegradable as the worst case.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

A key study for readily biodegradability is waived and the substance is treated to be not readily biodegradable as the worst case. This is supported by the available study (Scholtz 1996, Reliability 3), that was not performed according to guidelines or GLP criteria. In addition, the conclusion of non-ready biodegradability is also supported by the results of QSAR models (BIOWIN). Both BIOWIN 1 (= 0.2423, Linear model) and BIOWIN 2 (= 0.0076, Non-linear model) showed values less than the cut-off point (0.5). Thus, the substance is not readily biodegradable according to ECHA Guidance on information requirements and chemical safety assessment, Chapter R.7b: Endpoint specific guidance (Version 4.0 June 2017).