cis-4-[3-(p-tert-butylphenyl)-2-methylpropyl]-2,6-dimethylmorpholine

Biodegradation in soil

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in soil, other

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Principles of method if other than guideline:

calculation

GLP compliance:

no

Test type:

other: calculation based on study results

Details on experimental conditions:

The degradation of fenpropimorph in soil systems was investigated under field conditions in Germany during the years 1990 and 1991 according to BBA Guideline Part IV, 4-1 (1991/10760 and 1992/1000183). The experimental results of these studies were evaluated at that time according to the method proposed by Timme and Frehse. In the present modelling exercise the data were evaluated according to current procedures in order to develop an appropriate mathematical model and to derive degradation parameters by non-linear parameter estimation methods.

Kinetic models recommended by FOCUS kinetics were used aiming at the description of the dissipation of fenpropimorph from the soil system and at deriving dissipation times 50 and 90. Single First Order (SFO) and First Order Multiple Compartment (FOMC) kinetics were applied in the Model Maker software package and calculated concentration curves were fitted against the experimental results via the non-linear regression algorithm of Marquardt-Levenberg as implemented in Model Maker. The best fit calculation according to SFO or FOMC kinetic models were used to derive DT50 and DT90 values.

DT50:

8.8 d

St. dev.:

1

Type:

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

Remarks on result:

other: estimated degradation parameter; kinetic modell: SFO

DT50:

23.4 d

St. dev.:

0.982

Type:

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

Remarks on result:

other: estimated degradation parameter; kinetic modell: FOMC

DT50:

9 d

St. dev.:

0.966

Type:

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

Remarks on result:

other: estimated degradation parameter; kinetic modell: FOMC

DT50:

18.1 d

St. dev.:

0.99

Type:

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

Remarks on result:

other: estimated degradation parameter; kinetic modell: SFO

DT50:

50.6 d

St. dev.:

0.98

Type:

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

Remarks on result:

other: estimated degradation parameter; kinetic modell: FOMC

Details on results:

The resulting degradation parameters showed that dissipation followed SFO in two out of five trials and the remaining three trials showed significantly better fit with a FOMC model. DT50 and DT90 values as well kinetic parameter are listed in Table 1. The very long DT90 values calculated with the FOMC model have no significance, as no temperature and moisture corrected was performed to take the slower degradation during winter and early spring into account.

Table 1: Estimated degradation parameters
Field trial (reference)	Location (Country)	DT50 (d)	DT90 (d)	Kinetic model	r^2	Observation error**
AGR/10 (1991/10760)	Hoheneggelsen (FRG)	18.1	60.1	SFO C1 0.2318 k12 0.0383	0.9895	7.89
VTU/80 (1991/10760)	Stetten (FRG)	50.6	longer 2 x study*	FOMC M0 0.3311 alpha 0.3733 beta 9.4143	0.9803	5.74
D07/90/91 (1992/1000183)	Oberding (FRG)	8.8	29.4	SFO C1 0.2249 k12 0.0783	0.9997	1.54
D08/54/91 (1992/1000183)	Brockhausen (FRG)	23.4	longer 2 x study*	FOMC M0 0.6058 alpha 0.79927 beta 16.967	0.9822	9.35
DU1/22/91 (1992/1000183)	Birkenheide (FRG)	9.0	285.5*	FOMC M0 0.5270 alpha 0.2260 beta 0.4401	0.9655	9.77

*theoretical value - not significant, since no temperature and moisture correction was done
**calculated according to FOCUS recommendation Chi² test

Reference 2

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29.01.2004 - 23.03.2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)

Qualifier:

according to guideline

Guideline:

other: BBA IV 4-1; SETAC Procedures for assessing the environmental fate and ecotoxicity for pesticides

Version / remarks:

March 1995

GLP compliance:

yes (incl. QA statement)

Test type:

laboratory

Radiolabelling:

yes

Remarks:

[morpholine-2-14C] and [phenyl-U-14C] labeled BAS 421 (Fenpropimorph)

Oxygen conditions:

aerobic

Soil classification:

USDA (US Department of Agriculture)

Remarks:

Sandy loam

Year:

2005

Soil no.:

#1

Soil type:

sandy loam

% Clay:

ca. 11.6

% Silt:

ca. 33.1

% Sand:

ca. 55.4

% Org. C:

2.26

pH:

7.34

CEC:

14 meq/100 g soil d.w.

Details on soil characteristics:

Origin: Bruch West, Germany
Microbial biomass (mg C/100 g dry soil): 32.8
MWC (g H2O/100 g dry soil): 38.7

Soil No.:

#1

Duration:

149 d

Soil No.:

#1

Initial conc.:

2 mg/kg soil d.w.

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

CO2 evolution

Soil No.:

#1

Temp.:

20°C

Humidity:

40% maximum waterholding capacity (MWC)

Microbial biomass:

32.8 mg C/100 g dry soil

Details on experimental conditions:

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

Soil No.:

#1

% CO2:

38.6

% Recovery:

93.6

Remarks on result:

other: phenyl labeled test item

Soil No.:

#1

% CO2:

52.5

% Recovery:

88.9

Remarks on result:

other: morpholine labeled test item

Soil No.:

#1

% Degr.:

36

Parameter:

CO2 evolution

Sampling time:

119 d

Remarks on result:

other: phenyl labeled

Soil No.:

#1

% Degr.:

32.8

Parameter:

CO2 evolution

Sampling time:

91 d

Remarks on result:

other: phenyl labeled

Soil No.:

#1

% Degr.:

49.4

Parameter:

CO2 evolution

Sampling time:

119 d

Remarks on result:

other: morpholine labeled

Soil No.:

#1

% Degr.:

45.8

Parameter:

CO2 evolution

Sampling time:

91 d

Remarks on result:

other: morpholine labeled

Soil No.:

#1

DT50:

13.2 d

Type:

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

Remarks on result:

other: phenyl labeled

Soil No.:

#1

DT50:

11.8 d

Type:

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

Remarks on result:

other: morpholine labeled

Transformation products:

yes

Remarks:

Fenpropimorph-acid (BF 421-2; Reg.No. 231346), confirmed after HPLC-MS; morpholine 14C-labelled, ≥ 5 % DAT 3-22; max. 7.8 % at DAT 10-14 phenyl 14C-labelled ≥ 5 % DAT 3-27; max. 9.7 % at DAT 14

No.:

#1

Volatile metabolites:

no

Residues:

yes

Details on results:

Summing-up the results of all investigations in this study it can be concluded that fenpropimorph is aerobically degradable in a loamy sand with a DT50 of 12.5 days (average from DT50_morpholine = 11.8 d and DT50_phenyl = 13.2 d).
One degradation product of fenpropimorph was detected above 5% of the total applied radioactivity (TAR). Fenpropimorph-acid (Reg. No. 231346, BF 421-2) occurred with max. 7.8% TAR at 10 DAT in the soil treated with the morpholine labeled test item and with max. 9.7% TAR after 14 DAT in the soil treated with the phenyl labeled test item. The DT50 value for the main metabolite fenpropimorph-acid was determined to be 4.1 days.

In the soil treated with the morpholine labeled test item the non-extractable residues (NER) had its maximum with 37.0% TAR after 119 DAT. The fulvic acid fraction had its maximum with 11.7% TAR after 22 DAT. The humic acids fraction reached 1.9% TAR after 58 DAT.

In the soil treated with the phenyl labeled test item NER had its maximum with 55.6% TAR after 91 DAT. 4.9% of TAR could be assigned to the fulvic acid fraction after 27 DAT and 58 DAT. The humic acids reached 1.4 % TAR at the end of incubation.

At the end of incubation the mineralization reached 52.5% TAR in the soil treated with the morpholine labeled test item and 38.6% TAR in the soil treated with phenyl labeled test item, respectively.
No other volatile products besides C02 were detected.

Table 1:  Material balance and distribution of radioactivity after application of fenpropimorph to soil, morpholine label (% TAR)
	DAT	ERR I			ERR II	NER	^14CO2	Other volatiles	Material balance ERR + ERR II + NER + ^14CO2 + volatiles
		MeOH	MeOH/H2O	Total	NaOH + H2O
	0**	94.6	3.5	98.1	n.d.	1.9*	n.d.	n.d.	100.0
	1	86.1	6.5	92.6	2.9	3.7	1.3	0.0	100.5
	3	76.4	9.0	85.4	4.9	4.6	1.8	0.0	96.7
	7	62.5	10.7	73.2	8.4	13.7	5.9	0.0	101.2
	10	54.6	11.5	66.1	11.5	20.3	8.3	0.0	106.2
	14	46.8	12.0	58.8	13.0	18.2	11.7	0.0	101.7
	22	33.3	10.8	44.1	16.2	22.4	14.4	0.0	97.1
	27	26.7	10.3	37.0	17.0	34.8	17.5	0.0	106.3
	58**	7.9	4.7	12.6	18.3	29.4	37.8	0.0	98.1
	91	4.5	2.8	7.3	16.1	33.6	45.8	0.0	102.8
	119	3.7	2.2	5.9	13.7	37.0	49.4	0.0	106.0
	149	3.1	2.1	5.2	12.9	22.4	52.5	0.0	93.0

* NER at day 0 was determined by combustion of the soil after the methanol/water extraction
** mean value of  2 replicates

 

Table 2:  Material balance and distribution of radioactivity after application of fenpropimorph to soil, phenyl label (% TAR)
	DAT	ERR I			ERR II	NER	^14CO2	Other volatiles	Material balance ERR + ERR II + NER + ^14CO2 + volatiles
		MeOH	MeOH/H2O	Total	NaOH + H2O
	0**	95.7	3.3	99.0	n.d.	1.0*	n.d.	n.d.	100.0
	1	93.3	5.9	99.2	2.2	2.0	0.3	0.0	103.7
	3	78.6	7.3	85.9	4.2	5.2	1.0	0.0	96.3
	7	67.9	8.7	76.6	5.6	14.3	3.1	0.0	99.6
	10	59.5	8.6	68.1	7.9	11.5	4.1	0.0	91.6
	14	53.0	9.7	62.7	7.5	31.0	5.8	0.0	107.0
	22	39.1	7.8	46.9	8.4	32.3	7.5	0.0	95.1
	27	31.2	6.8	38.0	9.0	35.0	10.6	0.0	92.6
	58**	8.2	2.7	10.9	10.7	48.6	26.2	0.0	96.4
	91	4.7	1.8	6.5	9.5	55.6	32.8	0.0	104.4
	119	4.4	1.7	6.1	9.3	50.5	36.0	0.0	101.9
	149	3.4	1.3	4.7	10.4	47.2	38.6	0.0	100.9

n.d.:        not determined
* NER at day 0 was determined by combustion of the soil after the methanol/water extraction
** mean value of  2 replicates

 

Table 3:  Distribution of radioactivity, morpholine label (% TAR)
	DAT	Polar fraction*	fenpropimorph- acid	fenpropimorph	Others**	Bound***	^14CO2	Total
	0****	1.7	0.0	91.1	5.3	1.9	n.d.	100.0
	1	1.1	2.5	84.3	4.7	6.6	1.3	100.5
	3	3.5	5.0	75.2	1.7	9.5	1.8	96.7
	7	5.7	7.0	55.3	5.2	22.1	5.9	101.2
	10	6.5	7.8	46.9	4.9	31.8	8.3	106.2
	14	6.6	7.8	39.6	4.8	31.2	11.7	101.7
	22	6.5	5.1	26.8	5.7	38.6	14.4	97.1
	27	7.1	3.5	19.9	6.5	51.8	17.5	106.3
	58****	4.8	0.2	5.0	2.6	47.7	37.8	98.1
	91	2.2	0.1	2.8	2.2	49.7	45.8	102.8
	119	2.6	0.0	2.5	0.8	50.7	49.4	106.0
	149	2.7	0.0	2.1	0.4	35.3	52.5	93.0

*    HPLC retention time 3 min, consists of several peaks, each below 5 % TAR
**  all peaks were below 5% TAR
*** Bound = NaOH + H₂O + NER
**** mean value of  2 replicates

 

Table 4:  Distribution of radioactivity, phenyl label (% TAR)
	DAT	Polar fraction*	fenpropimorph- acid	fenpropimorph	Others**	Bound***	^14CO2	Total
	0****	0.0	0.0	96.1	2.9	1.0	n.d.	100.0
	1	0.0	2.9	93.0	3.3	4.2	0.3	103.7
	3	0.2	5.5	75.8	4.4	9.4	1.0	96.3
	7	0.7	8.5	62.3	5.1	19.9	3.1	99.6
	10	0.6	9.0	53.8	4.7	19.4	4.1	91.6
	14	1.3	9.7	43.2	8.5	38.5	5.8	107.0
	22	1.3	6.9	31.2	7.5	40.7	7.6	95.2
	27	1.5	5.5	26.1	4.9	44.0	10.6	92.6
	58****	2.3	0.3	7.1	1.2	59.3	26.2	96.4
	91	2.1	0.2	3.6	0.5	65.1	32.8	104.3
	119	2.3	0.1	3.3	0.4	59.8	36.0	101.9
	149	1.7	0.1	2.7	0.2	57.6	38.6	100.9

*    HPLC retention time 3 min, consists of several peaks
**  all peaks were below 5% TAR
*** Bound = NaOH + H₂O + NER
**** mean value of  2 replicates

 

Conclusions:

Summing-up the results of all investigations in this study it can be concluded that fenpropimorph is aerobically degradable in a sandy loam with a DT50 of 12.5 days.

Description of key information

Fenpropimorph is completely degradable in soil under aerobic conditions. This can be proved by the significant amount of CO₂ that is released from different parts of the molecule in soil. A full description of mass balance and mineralization is given in a metabolism study with [phenyl-U-¹⁴C] and [morpholin-2-¹⁴C] fenpropimorph according to OECD 307 (Key study, 2004/1022507). One degradation product was detected, fenpropimorph-acid occurred with max. 9.7% TAR after 14 days in the phenyl labeled study and with max. 7.8% TAR after 10 days in the morpholine labeled study.
The degradation rate (DT₅₀) of fenpropimorph was calculated to be 11.8 days for the morpholine label and 13.2 days for the phenyl label, i.e. the mean value is 12.5 days. The DT₅₀ value for the main metabolite fenpropimorph-acid was determined to be 4.1 days.
At the end of incubation the mineralization reached 52.5% TAR in the soil treated with the morpholine labeled test item and 38.6% TAR in the soil treated with phenyl labeled test item. Photolysis of fenpropimorph in soil is not a relevant degradation pathway since the absorption coefficient of fenpropimorph is <10L/(mol x cm) above 290 nm.

Considering the degradation data on fenpropimorph (2004/1022507) and the metabolite fenpropimorph-acid (2005/1010873), a summary of all laboratory half-lives was conducted and is presented in the following tables 1 and 2 below.
An overall geometric mean of 14.7 days half-life for fenpropimorph in soil was calculated.
A low degradation rate (DT₅₀ > 120 days) was found in anaerobic soil (1998/10367).

The degradation of fenpropimorph in soil systems was investigated under field conditions in Germany during the years 1990 and 1991 according to BBA Guideline Part IV, 4-1 (1991/10760 and 1992/1000183). The experimental results of these studies were evaluated at that time according to the method proposed by Timme and Frehse. In the present modelling exercise the data were evaluated according to current procedures in order to develop an appropriate mathematical model and to derive degradation parameters by non-linear parameter estimation methods, summarized in table 3.

Key value for chemical safety assessment

Half-life in soil:

12.5 d

at the temperature of:

20 °C

Additional information

Table 1: DT50 values of fenpropimorph, normalised to 20°C and soil moisture at pF2

Soil location (reference)			experimental Qact.  / temperature	Soil type	DT500 normalised	DT50 normalised Geometric mean^2)
			(%MWHC/°C)		(d)	(d)
(1979/10024)			40/22	Sandy loam	19.2	19.2
Neuhofen (1978/1000021)			40/20	Loamy sand	123.8^1)	(123.8)
Hatzenbühl (1978/1000021)			40/20	Loamy sand	16.7	16.7
			40/5		32.2	16.7
			20/20		25.5
Kirchheim (1985/10061)			40/20	Clay loam	12.2
			60/20		8.5
			40/30		15.3
			40/5		21.2	12.0
			20/20		6.2
Limburgerhof (1985/10061)			40/20	Sandy loam	10.0
			60/20		13.5
			40/30		13.9
Bruch West (2004/1022507) "morpholine label experiment"			40/20	Sandy loam	10.2	10.8
Bruch West (2004/1022507 "phenyl label experiment"			40/20		11.4
Overall geometric mean						14.7

¹⁾outlier not used for the averaging procedure (identified using the Grubbs outlier test on a significance level of 0.05)
²⁾geometric mean of normalised DT50 values calculated for identical soils

 

Table 2: DT50 values of fenpropimorph-acid, normalised to 20°C and soil moisture at pF2

Soil location (reference)		experimental Qact.  / temperature (%MWHC/°C)	Soil type	DT50 normalised   (d)	DT50 normalised Geometric mean^1) (d)
Bruch West (2004/1022507) "morpholine label experiment"		40/20		3.3
Bruch West (2004/1022507) "phenyl label experiment"		40/20	Sandy loam	3.8	3.8
Bruch West (2005/1010873)		40/20		4.2
Lufa 3A/ Ebert , Harder (2005/1010873)		40/20	Loam	3.4	3.4
Li10/ Ebert , Harder (2005/1010873)		40/20	Loamy sand	8.9	8.9
Overall geometric mean					4.9

¹⁾geometric mean of normalised DT50 values calculated for identical soils

 

Table 3: Estimated degradation parameters
Field trial (reference)	Location (Country)	DT50 (d)	DT90 (d)	Kinetic model	r^2	Observation error**
AGR/10 (1991/10760)	Hoheneggelsen (FRG)	18.1	60.1	SFO C1 0.2318 k12 0.0383	0.9895	7.89
VTU/80 (1991/10760)	Stetten (FRG)	50.6	longer 2 x study*	FOMC M0 0.3311 alpha 0.3733 beta 9.4143	0.9803	5.74
D07/90/91 (1992/1000183)	Oberding (FRG)	8.8	29.4	SFO C1 0.2249 k12 0.0783	0.9997	1.54
D08/54/91 (1992/1000183)	Brockhausen (FRG)	23.4	longer 2 x study*	FOMC M0 0.6058 alpha 0.79927 beta 16.967	0.9822	9.35
DU1/22/91 (1992/1000183)	Birkenheide (FRG)	9.0	285.5*	FOMC M0 0.5270 alpha 0.2260 beta 0.4401	0.9655	9.77

*theoretical value - not significant, since no temperature and moisture correction was done
**calculated according to FOCUS recommendation Chi² test