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

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16.04.1999- 20.07.2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: BBA Guidelines, Part IV, 5-1

Qualifier:

according to guideline

Guideline:

other: SETAC Europe, Part 8.2

Qualifier:

according to guideline

Guideline:

EPA Subdivision N Pesticide Guideline 162-4 (Aerobic Aquatic Metabolism)

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Remarks:

both radiolabelled forms of BAS 421F, phenyl-[14C] and morpholine-[14C] were used and applied

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

System A : Kellmetschweiher, Rhineland-Palatinate, FRG
pH: 8.42
hardness (mmol/l): 1.44
TOC (mg/l): 10.1
total N (mg/l): 3
total P (mg/l): <3

System B : Ranschgraben, Rhineland-Palatinate, FRG
pH: 7.85
hardness (mmol/l): 1.04
TOC (mg/l): 3.1
total N (mg/l): 5
total P (mg/l): <3

Details on source and properties of sediment:

System A : Kellmetschweiher; Rhineland-Palatinate, FRG
sand (%): 85
silt (%): 7
clay (%): 8
textural class (German scheme): clayey sand / loamy sand
pH (CaCl2): 7.4
organic C (%): 1.0
total N (%): 0.07
total P (%): 0.008
CEC (mVal/100g): 15
ATP (µg/kg): 45
plate counts (cfu/g)
bacteria: 1.8 x 10^6
actinomycetes: 3.9 x 10^4
fungi: 1.4 x 10^3

System B : Ranschgraben, Rhineland-Palatinate, FRG
sand (%): 79
silt (%): 16
clay (%): 5
textural class (German scheme): silty sand / loamy sand
pH (CaCl2): 5.4
organic C (%): 5.3
total N (%): 0.41
total P (%): 0.12
CEC (mVal/100g): 20
ATP (µg/kg): 1531
plate counts (cfu/g)
bacteria: 8.0 x 10^6
actinomycetes: 1.8 x 10^6
fungi: 9.0 x 10^4

Details on inoculum:

75 µg of 14C-BAS 421 F were applied per test vessels which corresponds to a eld application rate of 750 g BAS 421 F per hectare. The concentration in the test system was about 250 µg/l.

Duration of test (contact time):

100 d

Initial conc.:

250 µg/L

Based on:

test mat.

Details on study design:

BAS 421 F was applied to the water at a rate of 75 µg a.s. per test vessel which corresponded to the maximum recommended rate of 750 g as/ha when related to a 30 cm deep water body. Experiments under sterile conditions were also carried out in both water/sediment systems. For the isolation and identification of degradation products, some water/sediment systems were additionally treated at an application rate of 200 µg a.s. per test vessel. The test vessels were incubated in the dark at a temperature of 20 ± 2 °C for up to 100 days. Aeration was achieved by a stream of air over the water surface. A trapping system for volatiles was connected to each test vessel (except the sterilised vessels).

Compartment:

natural water / sediment: freshwater

% Recovery:

92.6

Key result

Compartment:

natural water / sediment: freshwater

DT50:

54 d

St. dev.:

0.99

Type:

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

Temp.:

20 °C

Remarks on result:

other: Kellmetschweiher system

Remarks:

in whole system

Key result

Compartment:

natural water: freshwater

DT50:

3.4 d

St. dev.:

0.98

Type:

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

Temp.:

20 °C

Remarks on result:

other: Kellmetschweiher system in water compartment

Key result

Compartment:

natural sediment: freshwater

DT50:

83.6 d

St. dev.:

0.98

Type:

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

Temp.:

20 °C

Remarks on result:

other: Kellmetschweiher system

Remarks:

in sediment compartment

Key result

Compartment:

natural water / sediment: freshwater

DT50:

18 d

St. dev.:

0.99

Type:

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

Temp.:

20 °C

Remarks on result:

other: Ranschgraben system

Remarks:

in whole system

Key result

Compartment:

natural water: freshwater

DT50:

1.9 d

St. dev.:

0.98

Type:

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

Temp.:

20 °C

Remarks on result:

other: Ranschgraben system

Remarks:

in water compartment

Key result

Compartment:

natural sediment: freshwater

Type:

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

Temp.:

20 °C

Remarks on result:

not determinable

Remarks:

Ranschgraben system in sediment compartment

Transformation products:

yes

No.:

#1

Volatile metabolites:

no

Details on results:

The results from the two different radiolabels revealed no sigificant differences; therefore the differently radiolabelled replicates were averaged. The distribution and recovery of radioactivity from water/sediment system A is shown in Table 1, the corresponding results from system B are presented in Table 2.
In both systems, the radioactivity moved quite fast from the water into the sediment. However, in system A, the radioactivity increased again from 17% TAR to 29% TAR in the time period from 29 to 100 days. This indicates that a metabolite formed in the sediment moved back into the water. In system B, the same phenomenon seems to appear, however, after a short increase of the radioactivity in the water, it decreased further down to 12% TAR at the end of the study. Mineralisation was moderate in both systems reaching 6.3 and 8.5% TAR (system A/B) and no other volatile degradates were detected.
In system A, the bound residues in the sediment increased slowly reaching about 20% TAR at the end of the study. In system B, the bound residues reached about 28% after 29 days, but then decreased again to 37% TAR at the end of the study.

A comprehensive overview on the results of the HPLC analysis of the water and of the extracts of sediment is shown in Table 3 for system A and in Table 4 for system B.
Fenpropimorph (BAS 421 F) and the metabolite fenpropimorph-acid (BF 421-2) were the major compounds in both water/sediment systems. In the water phase, the metabolite fenpropimorph-acid reached maximum amounts of about 23 / 17% TAR (system A/B). In the sediment, the metabolite appeared only at the last three sampling times and only in amounts <8% TAR. Since the radioactivity in the water phase first decreases, but then increases again, it can be assumed that at least a major part of the fenpropimorph-acid was formed in the sediment and moved back into the water.

Mathematical evaluation of the disappearance of fenpropimorph and metabolite fenpropimorph-acid was performed using the computer program ModelMaker, version 3.0.4.

Table 1:  Material balance and distribution of radioactivity after application of (^14C)-fenpropimorph to water/sediment system A (%TAR)
DAT	water	sediment					CO2	balance
		extractable residues			bound residues	total
		ACN/H2O	ACN	total
0 0.25 1 2 7 14 29 63 100	70.5 77.0 61.3 46.5 23.9 17.4 16.8 26.1 28.8	4.6 3.6 7.2 10.9 14.9 17.7 16.7 19.2 20.2	8.8 5.6 14.3 20.6 32.4 32.2 30.7 20.6 16.9	13.4 9.3 21.4 31.6 47.3 49.9 47.4 39.9 37.1	6.7 4.7 9.7 14.8 23.9 26.6 27.5 23.6 20.0	20.1 14.0 31.1 46.4 71.2 76.5 75.0 63.5 57.1	n.d. 0.0 0.0 0.1 0.4 0.7 1.7 4.5 6.3	90.6 91.0 92.4 93.0 95.4 94.7 93.4 94.1 92.2
101 s	4.5	37.2	35.2	72.5	15.5	88.0	n.d.	92.4

s           = sterilised

n.d.      = not determined

 

 

Table 2:  Material balance and distribution of radioactivity after application of (^14C)-fenpropimorph to water/sediment system B (%TAR)
DAT	water	sediment					CO2	balance
		extractable residues			bound residues	total
		ACN/H2O	ACN	total
0 0.25 1 2 7 14 29 63 100	75.0 73.3 50.3 39.0 23.5 19.0 21.4 17.6 12.0	3.4 3.6 8.0 10.0 12.4 13.7 13.8 14.1 14.2	8.2 8.0 20.8 24.2 32.3 31.2 22.8 17.3 20.3	11.7 11.7 28.8 34.2 44.8 45.0 36.6 31.5 34.5	5.9 6.3 12.7 17.7 24.4 27.2 30.1 36.4 36.8	17.5 17.9 41.5 51.9 69.2 72.2 66.6 67.9 71.3	n.d. 0.0 0.1 0.1 0.7 2.0 4.1 7.5 8.5	92.5 91.2 91.9 91.0 93.3 93.1 92.1 93.1 91.9
101 s	5.2	27.4	41.4	68.7	19.7	88.4	n.d.	93.6

s           = sterilised

n.d.      = not determined

 

Table 3:  HPLC analysis of the water and the extracts of the sediment of system A after application of (^14C)-fenpropimorph (%TAR)
DAT	fenpropimorph	fenpropimorph-acid	others	total
water
0         0.25              1              2              7            14            29            63          100	70.1 73.5 60.1 43.4 19.8 7.6 4.5 3.0 2.7	0.0 0.0 0.0 0.0 1.7 6.5 9.3 20.5 22.6	0.4 3.4 1.2 3.1 2.4 3.4 3.0 2.6 3.5	70.5 77.0 61.3 46.5 23.9 17.4 16.8 26.1 28.8
101 s	2.3	0.0	2.2	4.5
sediment
0         0.25              1              2              7            14            29            63          100	13.2 9.3 20.9 30.0 46.9 48.2 46.2 34.7 28.2	0.0 0.0 0.0 0.0 0.0 0.0 0.2 4.1 7.7	0.1 0.0 0.5 1.6 0.4 1.7 1.1 1.1 1.2	13.4 9.3 21.4 31.6 47.3 49.9 47.4 39.9 37.1
101 s	72.5	0.0	0.0	72.5

s = sterilised

 

Table 4:  HPLC analysis of the water and the extracts of the sediment of system B after application of (^14C)-fenpropimorph (%TAR)
DAT	fenpropimorph	fenpropimorph-acid	others	total
water
0         0.25              1              2              7            14            29            63          100	73.5 68.9 48.6 36.1 9.1 4.5 2.0 0.7 1.0	0.0 0.0 0.0 0.0 7.5 10.9 16.9 14.0 8.6	1.5 4.3 1.7 2.9 6.8 3.6 2.5 3.0 2.4	75.0 73.3 50.3 39.0 23.5 19.0 21.4 17.6 12.0
101 s	2.6	0.0	2.6	5.2
sediment
0         0.25              1              2              7            14            29            63          100	11.5 11.7 28.8 33.3 44.8 44.6 32.0 25.7 27.4	0.0 0.0 0.0 0.0 0.0 0.0 4.3 5.2 5.7	0.1 0.0 0.0 1.0 0.0 0.4 0.3 0.6 1.3	11.7 11.7 28.8 34.2 44.8 45.0 36.6 31.5 34.5
101 s	67.6	0.0	1.1	68.7

s = sterilised

 

Table 5:  Dissipation rates of fenpropimorph in water sediment systems
System A (Kellmetschweiher)	DT50 (days)	DT90 (days)	r^2
fenpropimorph (BAS 421 F)      (water)	3.4	11.1	0.98
fenpropimorph (BAS 421 F)      (sediment)	83.6	^1)	0.98
BAS 421         (total system)	54	^1)	0.99
fenpropimorph-acid (BAS 421-2)      (water)	120.7	^1)	0.98
System B (Ranschgraben)	DT50 (days)	DT90 (days)	r^2
fenpropimorph (BAS 421 F)      (water)	1.9	6.4	0.98
fenpropimorph (BAS 421 F)      (sediment)	^2)	^2)	0.98
BAS 421         (total system)	18	^1)	0.99
fenpropimorph-acid (BAS 421-2)      (water)	38.7	^1)	0.98

¹⁾ value > 2 times study duration
²⁾ no estimation possible

 

Conclusions:

Fenpropimorph has a low water solubility and a high adsorption coefficient, which leads to a fast movement into the sediment. Within the sediment, fenpropimorph is oxidised to the metabolite fenpropimorph-acid, which has a much better solubility and a weaker adsorption. Therefore fenpropimorph-acid moves back to the water phase and is mainly found in it. It can further be metabolized and the final mineralisation to CO2 to 6% to 8% of the applied radioactivity is significant. The amounts of bound residues are moderate.

Description of key information

Fenpropimorph has a low water solubility and a high adsorption coefficient, which leads to a fast movement into the sediment. Within the sediment, fenpropimorph is oxidised to the metabolite fenpropimorph-acid, which has a much better solubility and a weaker adsorption. Therefore fenpropimorph-acid moves back to the water phase and is mainly found in it. It can further be metabolized and a final mineralisation to CO₂ to 6% to 8% of the applied radioactivity is reached. The amounts of bound residues are in System A 20.0 % and in system B 36.8 %.

The DT₅₀ values for the two total systems were 54 and 18 days, forming a mean value of 36 days. For the water phase DT₅₀ values of 1.9 and 3.4 days were detremined, resulting in a mean value of 2.65 days, compare BASF key study 2000/10000146.

 

The DT₅₀ values of the metabolite fenpropimorph-acid in the two water phases were 39 and 121 days (2000/1000146).

Key value for chemical safety assessment

Half-life in freshwater:

2.65 d

at the temperature of:

20 °C

Half-life in freshwater sediment:

31.2 d

at the temperature of:

20 °C

Whole System

Half-life in whole system:

36 d

at the temperature of:

20 °C

Type of system:

fresh water and sediment

Additional information

The geometric mean degradation half-life of fenpropimorph in fresh water systems was found to be 2.5 days.
The half-life of fenpropimorph in one of the sediment systems was found to be 83.6 days; for the other system no DT50 value could be determined since it exceded the duration of the study of 100 days.