1-[2-(allyloxy)ethyl-2-(2,4-dichlorophenyl)-1H-imidazolium hydrogen sulphate

Biodegradation in soil

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in soil: simulation testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Data from the related substance imazalil base is used to cover this endpoint. The justification for read across is attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Soil No.:

#2

DT50:

474 d

Type:

other: normalised

Temp.:

25 °C

Key result

Soil No.:

#3

DT50:

50.8 d

Type:

other: normalised

Temp.:

20 °C

Key result

Soil No.:

#4

DT50:

57.1 d

Type:

other: nomalised

Temp.:

20 °C

Key result

Soil No.:

#5

DT50:

53.4 d

Type:

other: nomalised

Temp.:

20 °C

Key result

Soil No.:

#6

DT50:

95.7 d

Type:

other: normalised

Temp.:

20 °C

Transformation products:

not specified

Reference 2

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Deviations:

no

GLP compliance:

not specified

Remarks:

Study performed under revision of Imazalil (not REACh related)

Test type:

laboratory

Specific details on test material used for the study:

chemical purity:not reported
Radiochemical purity > 98% both 14C-imazalil compounds
14C-imazalil (14C-phenyl-ring)
14C-imazalil(14C-imidazole-ring)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

USDA (US Department of Agriculture)

Soil no.:

#1

Soil type:

sandy loam

% Clay:

8.82

% Silt:

36.55

% Sand:

54.63

% Org. C:

1.64

pH:

7.92

CEC:

8.96 meq/100 g soil d.w.

Details on soil characteristics:

agriculatural soil from Sevelen (Switzerland)

Soil No.:

#1

Duration:

120 d

Soil No.:

#1

Initial conc.:

0.2 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Soil No.:

#1

Temp.:

20 °C

Humidity:

pF 2.5

Microbial biomass:

Day 0: 22.15/55.29 (2.4% of OC)

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Soil preincubation conditions (duration, temperature if applicable): test soils were collected from sites untreated with pesticides and fertilisers for the previous 5 years. Following field collection and sieving (2 mm) they were stored aerobically at the test facility for about one month at 1-10°C. Before use the soils were conditioned to room temperature for 1 day. The soil was prepared by sieving through a 2 mm mesh after which 100 g of dry soil equivalents were weighed into each 300 mL-Erlenmeyer test flasks that were fitted with trap attachments for absorption of 14CO2.
- Soil condition: dry
- Soil (g/replicate): 100g
- Control conditions, if used (present differences from other treatments, i.e., sterile/non-sterile, experimental conditions):
- No. of replication controls, if used: duplicates
- No. of replication treatments: duplicates
- Test apparatus (Type/material/volume):
- Details of traps for CO2 and organic volatile, if any:
- If no traps were used, is the system closed/open:
- Identity and concentration of co-solvent:The radiolabelled test items (phenyl-ring-labelled and imidazole-ring-labelled Imazalil) were delivered in chloroform

Test material application
- Volume of test solution used/treatment: Application solutions of phenyl- and imidazole-labelled Imazalil were prepared and applied to the test soils at a concentration of 20.28 μg/100 g dry soil (phenyl) and 20.01 μg/100 g dry soil (imidazole).
- Application method (e.g. applied on surface, homogeneous mixing etc.): The applied radioactivity was incorporated into the soil by carefully hand shaking the flask to achieve a homogenous distribution of the radioactivity in soil.
- Is the co-solvent evaporated: The chloroform was evaporated to dryness and the test items were dissolved each in 10 mL acetone. The radioactivity of diluted aliquots of these solutions was measured by liquid scintillation counting (LSC) and the purity was determined by HPLC. The identity of the test item was confirmed by co-chromatography using the reference item of Imazalil.

Experimental conditions (in addition to defined fields)
- Continuous darkness: Yes

SAMPLING DETAILS
- Sampling intervals:Samples were taken immediately afte rthe application (day 0) and after 2, 7, 15, 30, 58, 90 and 120 days of incubation
- Sampling method for soil samples: . Prior to opening the metabolism vessel, i.e. for determination of soil moisture or processing of soil, volatile products still present in the test system were purged into the trap attachment.
- Method of collection of CO2 and volatile organic compounds: 14CO2 and othervolatile metabolites possiblybeing formed out of applied 14C-labelled test item were trapped in the soda lime trap attachment.
- Moisture content: pF 2.5

Soil No.:

#1

% Recovery:

92.41

Remarks on result:

other: phenyl-label

Soil No.:

#1

% Recovery:

95.99

Remarks on result:

other: imidazole label

Key result

Soil No.:

#1

% Degr.:

11.9

Parameter:

radiochem. meas.

Sampling time:

120 d

Key result

Soil No.:

#1

DT50:

28.1 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Transformation products:

yes

No.:

#1

Details on transformation products:

on the last sampling day a mean value of 18.3% AR could be determined as imazalil.
Metabolite R0148214 could be detected in only one interval.
Unknown fractions were detected, at day 120 unknown -5 was 3.3%

Volatile metabolites:

yes

Remarks:

CO2

Residues:

yes

Remarks:

non-extractable residues

Details on results:

the mineralization was high and accounted for 33.3% (phenyl) and 41.9% imidazole. The non-extractbel residues amounted to 38.4M (phenyl) and 30.1% AR (imidazole) after 120 days of incubation. No significant radio active fractions were observed. T014821 was detected at a maximum % of AR and all the other unkwon radion active fractions either did not exceed 5%AR or exceeded this value at only one measurement.

Conclusions:

Under aerobic conditions, imazalil was shown to disappear mainly by formation of non-extactable residues and mineralisation to carbon dioxide. The DT50 of imazalil was 18.9 days.

Reference 3

Endpoint:

biodegradation in soil: simulation testing

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

other: FOCUS guidance

Soil no.:

#1

Soil type:

loam

Soil no.:

#2

Soil type:

silt loam

Soil no.:

#3

Soil type:

sandy loam

Soil no.:

#4

Soil type:

silt loam

Soil no.:

#5

Soil type:

sandy clay loam

Key result

Soil No.:

#1

DT50:

474 d

Type:

other: normalised DFOP

Temp.:

25 °C

Key result

Soil No.:

#2

DT50:

50.8 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Key result

Soil No.:

#3

DT50:

57.1 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Key result

Soil No.:

#4

DT50:

53.4 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Key result

Soil No.:

#5

DT50:

95.7 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Conclusions:

The route and rate of degradation in soil of imazalil was evaluated during the Active substance renewal under EC regulation 1107/32009. The geometric mean of 5 soil was dtermined to be 93.2 d (n=5; SFO)

Reference 4

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1983-03-16 - 1984-03-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Guidance document on estimating persistence and degradation kinetics from Environmental Fate studies on pesticides in EU registration. (SANCO/10058/2005)

Version / remarks:

version 2.0

Deviations:

no

Principles of method if other than guideline:

Guidelines & limitations
1. No time zero measurement was performed. Because the concentration of the stock solution was
determined by LSC and the radiochemical purity was of 14C-imazalil was >99% it was concluded
that the soil was correctly dosed.
2. It was shown that the extractability of unaltered imazalil was
reduced with time. No assessment on the exhaustive nature of the current extraction method (which
was different from STUDY 1: 2 x MeOH followed by 2 x MeOH:NH4OH 99:1 v/v) could be made. [It
was determined that the current extraction method recovered >96% of applied radioactivity from
freshly spiked soil].
3. DT50 values were recalculated according to FOCUS kinetics. However the reliability of the
endpoints is questionable (see remark 2).

GLP compliance:

no

Test type:

laboratory

Specific details on test material used for the study:

The labelled imazalil was obtained as the sulphate salt (14Cr-R 27180).
Batch No 392 showed a specific activity of 600 kBq/mg.
purity: exceeding 99.5%
Unlabelled imazalil sukphate was from suntyhesis batch B4701. Purity exceeded 99.5%

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

USDA (US Department of Agriculture)

Year:

1983

Soil no.:

#1

Soil type:

loam

% Clay:

13.5

% Silt:

40.1

% Sand:

> 46.4

% Org. C:

4.7

pH:

7.1

CEC:

25.6 meq/100 g soil d.w.

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Geographic location: watervliet
- Pesticide use history at the collection site: non agricultural practive
- Soil preparation (e.g., 2 mm sieved; air dried etc.): the soil was spread in a thin layer over a filter sheet and air-dried at room temperature until screnning over a 2-mm sieve became feasible.

PROPERTIES OF THE SOILS (in addition to defined fields):
Texture characterization (%):
> 50 µm sand = 46.4%
2 µm-50 µm: loam = 40.1%
< 2 µm:c lay: 13.5%
organic matter (g/ 100 g oven-dry soil): 4.7
pH (H2O): 7.1
pH(KCl): 7.0
water capacity: g H2O/100g oven-dry soil): 48.6
cation exchange capacity: (meq/100g oven-dry soil): 25.6

Soil No.:

#1

Duration:

366 d

Soil No.:

#1

Initial conc.:

5 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Soil No.:

#1

Temp.:

25°C

Humidity:

24.3% (i.e. 50% of the MWHC of 48.6%-

Details on experimental conditions:

The transformations were studied in a set of flow-trough metabolism systems.
batch system: 100 ml gas washin bottle containing 50 ml of water to saturate the incoming air, a 1.0L incubation jar and a trapping line for volatiles, consisting of a 100 ml gas washing bottle cotaining 50 ml of ethylene glycol, a 100 ml gas washing bottle containg 50 ml H2SO4 0.1N and two gas washing bottles, each containing 50 ml of NaOH 2N.
The atmosphere of the incubation systems was continously renewed by delvering Co2-free air from a pressurized cylinder over a distribution manifold, a Hoke-needle valve and an all glass one-way valve.
the temperateure was controlled at 25°C +-0.2°C by a Thermomix 144L circulation pump.
An amount of air-dried and sieved soil, equivalent to 500 g of oven-dry soil was transferred to each of the incubation jars of 3 flow-trough metabolism systems. the volume of water needed to adjust the soil moisture content to 50 % of its water holding capacity was caclulated from the water content of the air-dried soil. A 2.5 mL aliqout of the 14C imazalil stock solution was diluted with distilled water to reach the calculated moistening volume and subsequently added dropwise to he soil. During addition of the 14C imazalil dose the soil was gently mixed. An application rate of 5 mg imazalil base per kg oven-dry soil equivalent resulted. The initial total radioactivity in the system was 70.55 x10^6 dmp.
One metabolism system was kept primarly for monitoring the volatile radioactivity. The contents of its incubation jar were left undisturbed during the whole incubation period. Both other systems were parallel incubations and received identical treatments. From the latter systems, soil samples were removed for analysis at the selected time intervals.
Before the incubation was started, the total weight of each incubation jar was recorded to enable a compensation of weight losses due to drying of the soil. At each sampling occasion the weight was adjusted by adding water. After soils sampling in systems B1 or B2 a new total weight of the incubation jar was calculated, correcting for the removed material. THe soil remaining in the incubation jar after the last samplling was freeze-dried crumbled and started at -20°C until needed.

Key result

Soil No.:

#1

DT50:

171 d

Type:

(pseudo-)first order (= half-life)

Temp.:

20 °C

Transformation products:

yes

No.:

#1

Details on transformation products:

FX contained a transformation product of imazalil yielding a major ion fragment with a m/e ratio of 247. The mass spectrum of the biodegradation products was in accordance with the monosilyated derivative of R 14821 (1-(2-(2.4-dhichlorophenyl)-2-hydroxyethyl)-1H-imidazole.

Residues:

yes

Remarks:

polar products

Details on results:

the extractable imazalil derived residues contained, in addition to the parent substance, some more polar transformation products; The majority of these products was eluted as a single fraction during reversed- phase radio HPLC analysis. This fraction reached about 10 % of the extractable residue at most, but its absolution concentration declined at a rate similar to the terminal transformation rate of the parent compound.
70% of the FX was shown to be 1(2(2,4-dichlorophenyl)-2-hydroxyetghyl)-1H-imidazole, the product of an 0-dealkylation fo imazalil. A large amount was mineralised to 14CO2 and a major part was transformed to soil-bound residue.

Conclusions:

For both experimental systems, the DT50 and DT90 were calculated for a first-order depletion. The DT50 was 171 days and DT90 were 566 days.

Reference 5

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

The results raised doubts about the exhaustive nature of the extraction procedures. The "extractables II" fraction (acetonitrile 1X plus acetonitrile/water (4/1) 1X) still contained 7.8 to 29% AR at 120 days. At 120 days, the harsh acidic reflux extraction released 8.3 - 10.5% AR (which consisted for 43% of imazalil for soil #3, results for other soils not reported). Harsh extractions were not performed for the other time points. Despite the fact that the time zero results showed good recoveries of radioactivity in the extracts (>98% AR), the harsh extractions of day 120 indicate that the extractability of unaltered imazalil decreased with time and a more exhaustive extraction should have been employed from day 7 onwards. Compounds extracted using acidic reflux extraction might also have been extracted using additional cold extractions with (acidified) aqueous acetonitrile. It is therefore concluded that no reliable assessment can be made on the occurence of metabolite fractions >5% AR and their maximum levels. Also, reliable DT50 values cannot be determined as it is likely that a significant amount of imazalil is still present in the reported extractable fraction. The label position does not allow to establish the degradation pathway (especially the occurence of phenyl and imidazole moiety containing degradation products). TLC was used as the main analytical method. Currently, there are more specific analytical techniques available for the identification of possible metabolites.

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Version / remarks:

2002

GLP compliance:

yes

Test type:

laboratory

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 2213

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: 97.28%

Radiolabelling:

yes

Remarks:

14C-imazalil

Oxygen conditions:

aerobic

Soil classification:

USDA (US Department of Agriculture)

Year:

2008

Soil no.:

#1

Soil type:

silt loam

% Clay:

12

% Silt:

53

% Sand:

35

% Org. C:

2.23

pH:

7.18

CEC:

15.07 meq/100 g soil d.w.

Soil no.:

#2

Soil type:

sandy loam

% Clay:

7

% Silt:

22

% Sand:

72

% Org. C:

1.23

pH:

7.24

CEC:

8.93 meq/100 g soil d.w.

Soil no.:

#3

Soil type:

silt loam

% Clay:

24

% Silt:

64

% Sand:

12

% Org. C:

1.37

pH:

7

CEC:

18.07 meq/100 g soil d.w.

Soil no.:

#4

Soil type:

sandy clay loam

% Clay:

25

% Silt:

26

% Sand:

49

% Org. C:

3.08

pH:

5.9

CEC:

21.66 meq/100 g soil d.w.

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Pesticide use history at the collection site: The test soils were collected from sites untreated with pesticides and fertilisers for the previous 5 years.
- Storage conditions: 4°C
- Storage length: about 1 month or used immediately
- Soil preparation (e.g., 2 mm sieved; air dried etc.): 2mm sieved

Soil No.:

#1

Duration:

120 d

Soil No.:

#2

Duration:

120 d

Soil No.:

#3

Duration:

120 d

Soil No.:

#4

Duration:

120 d

Soil No.:

#1

Initial conc.:

0.2 mg/kg soil d.w.

Based on:

act. ingr.

Soil No.:

#2

Initial conc.:

0.2 mg/kg soil d.w.

Based on:

act. ingr.

Soil No.:

#3

Initial conc.:

0.2 mg/kg soil d.w.

Based on:

act. ingr.

Soil No.:

#4

Initial conc.:

0.2 mg/kg soil d.w.

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

radiochem. meas.

Soil No.:

#1

Temp.:

20°C

Humidity:

2.0 - 2.5 pF

Microbial biomass:

458 - 481 µg C/g

Soil No.:

#2

Temp.:

20°C

Humidity:

2.0 - 2.5 pF

Microbial biomass:

249 - 245 µg C/g

Soil No.:

#3

Temp.:

20°C

Humidity:

2.0 - 2.5 pF

Microbial biomass:

275 - 352 µg C/g

Soil No.:

#3

Temp.:

10°C

Humidity:

2.0 - 2.5 pF

Microbial biomass:

275 - 441 µg C/g

Soil No.:

#4

Temp.:

20°C

Humidity:

2.0 - 2.5 pF

Microbial biomass:

404 - 501 µg C/g

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Soil preincubation conditions (duration, temperature if applicable): Before use the soils were conditioned to room temperature. The lenght of the conditioning period was not reported.
- Soil condition: air dried/fresh
- Soil (g/replicate): 100g/replicate
- No. of replication treatments: 2
- Details of traps for CO2 and organic volatile, if any: Volatiles in effluent air were trapped in ethylene glycol (1 trap) and CO2 was trapped in 2N NaOH (1 trap).
- Identity and concentration of co-solvent: 2.6% ethanol

Test material application
- Volume of test solution used/treatment: 0.54 ml
- Application method (e.g. applied on surface, homogeneous mixing etc.): 14C-imazalil was applied in 0.54 mL of 2.6% ethanol in water to the surface of the 100g dry weight portions of all 4 soils at a rate of 0.2 mg/kg. The treated soil was then mixed.

Experimental conditions (in addition to defined fields)
- Moisture maintenance method: The soils were incubated under a continuous humid air supply in the dark at 20+-2°C for up to 120 days. Soil #3 was also incubated at 10+-2°C. The soil moisture content was maintained between pF 2.0 and pF 2.5 throughout incubation.
- Continuous darkness: Yes

SAMPLING DETAILS
- Sampling intervals: days 7, 14, 29, 59, 91 and 120 post-treatment

Soil No.:

#1

% Recovery:

102.7

St. dev.:

1.4

Soil No.:

#2

% Recovery:

102.7

St. dev.:

2.4

Soil No.:

#3

% Recovery:

101.4

St. dev.:

3.2

Remarks on result:

other: 20°C

Soil No.:

#3

% Recovery:

103.4

St. dev.:

1.4

Remarks on result:

other: 10°C

Soil No.:

#4

% Recovery:

103.5

St. dev.:

2.5

Soil No.:

#1

Remarks on result:

not determinable because of methodological limitations

Soil No.:

#2

Remarks on result:

not determinable because of methodological limitations

Soil No.:

#3

Remarks on result:

not determinable because of methodological limitations

Soil No.:

#4

Remarks on result:

not determinable because of methodological limitations

Transformation products:

yes

Details on transformation products:

Eleven metabolites were measured. Only metabolite M5 exceeded 5% AR at two consecutive times (max 9.6% AR at day 120, 20°C; max 7.5% AR at day 120, 10°C). All other metabolite fractions were =< 5.1% AR. The results raised doubts about the exhaustive nature of the extraction procedures. The "extractables II" fraction still contained 7.8 to 29% AR at 120 days. At 120 days, the harsh, acidic reflux extraction released 8.3-11% AR (which consisted for 43% imazalil and 25% out of metabolite M5 for the Fislis soil, results for other soils not reported). Harsh extractions were not performed for the other time points. Despite the fact that the time zero results showed good recoveries of radioactivity in the extracts (> 98% AR), the harsh extractions of day 120 indicate that the extractability of unaltered imazalil decreased with time and a more exhaustive extraction should have been employed from day 7 onwards. It is therefore concluded that no reliable assessment can be made on the occurence of metabolite fractions > 5% AR and their maximum levels in soil.

Details on results:

TEST CONDITIONS
- Aerobicity (or anaerobicity), moisture, temperature and other experimental conditions maintained throughout the study: Yes

TRANSFORMATION PRODUCTS
- Range of maximum concentrations in % of the applied amount and day(s) of incubation when observed: 2.0 - 9.6%, day 120
- Range of maximum concentrations in % of the applied amount at end of study period: 2.0 - 9.6%, day 120

EXTRACTABLE RESIDUES
- % of applied amount at day 0:
* soil #1: 98.5%
* soil #2: 98.7%
* soil #3 (20°C): 98.1%
* soil #3 (10°C): 98.1%
* soil #4: 97.0%
- % of applied amount at end of study period:
* soil #1: 23.4%
* soil #2: 39.2%
* soil #3 (20°C): 33.4%
* soil #3 (10°C): 65.6%
* soil #4: 58.2%

NON-EXTRACTABLE RESIDUES
- % of applied amount at day 0:
* soil #1: 5.2%
* soil #2: 5.8%
* soil #3 (20°C): 6.8%
* soil #3 (10°C): 6.8%
* soil #4: 7.9%
- % of applied amount at end of study period:
* soil #1: 41.7%
* soil #2: 38.4%
* soil #3 (20°C): 44.9%
* soil #3 (10°C): 32.6%
* soil #4: 42.4%

MINERALISATION
- % of applied radioactivity present as CO2 at end of study:
* soil #1: 37.9%
* soil #2: 22.9%
* soil #3 (20°C): 19.0%
* soil #3 (10°C): 3.2%
* soil #4: 3.4%

VOLATILIZATION
- % of the applied radioactivity present as volatile organics at end of study:
* soil #1: <0.1%
* soil #2: <0.1%
* soil #3 (20°C): <0.1%
* soil #3 (10°C): <0.1%
* soil #4: <0.1%

RESULTS
* Reliable DT50 values cannot be determined as it is likely that a significant amount of imazalil is still present in the reported unextractable fraction.
* The time zero recovery for imazalil in soil #1 was only 73% AR. No clear reason for this observation was given.

Conclusions:

In 4 soils treated with imazalil at 0.2 mg/kg and incubated under aerobic conditions at 20°C in the dark, CO2 was evolved to a maximum of 3.4-3.7% AR on day 120 (3.2% at 10°C). Since the extraction procedures were probably not exhaustive enough, no reliable assessment can be made on the occurrence of metabolite fractions >5% AR and their maximum levels. Also, reliable DT50 values cannot be determide as it is likely that a significant amount of extractable imazalil was still present in the reported unextractable fraction.

Description of key information

No study was available on the biodegradation of the test substance imazalil sulfate in soil. Therefore, read across is performed using studies with imazalil. The DT50 has been derived on a normalised geomean (n=6) of 76.3 (EC, 2014, Post including addedum on confirmatory data Annex B B.8 Fate and behaviour).  

Key value for chemical safety assessment

Half-life in soil:

76.3 d

at the temperature of:

20 °C