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REACH

mancozeb (ISO); manganese ethylenebis(dithiocarbamate) (polymeric) complex with zinc salt

EC number: 616-995-5 | CAS number: 8018-01-7

Life Cycle description
Uses advised against

Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference 1

Endpoint:

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

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 2014 - July 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 309 (Aerobic Mineralisation in Surface Water - Simulation Biodegradation Test)

Version / remarks:

2004

Deviations:

GLP compliance:

yes

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on source and properties of surface water:

Water Carsington Water Reservoir:
pH at collection: 8.81
Colour: Non-turbid colourless
Dissolved oxygen at collection (%sat.): 138.3
Conductivity at collection (ppm): 185
Total hardness (mg equivalent CaCO3 /L): 92
Biological oxygen demand (mg/L): 0.0
Total organic carbon (TOC, mg/kg): 5.0
Dissolved Organic Carbon (DOC, mg/L): 4.2
Total phosphorus (mg/L): 0.1
Total nitrogen (mg/L): 1.6
Nitrate NO3- (mg/L): <0.1
Nitrite NO2- (mg/L): 1.2
Ammonium NH4+ (mg/L): <0.2

Duration of test (contact time):

61 d

Initial conc.:

96.62 µg/L

Based on:

other: [14C]-mancozeb was prepared for treatment as a suspension in dry ethanol; high dose 100 µg/L

Initial conc.:

9.1 µg/L

Based on:

other: [14C]-mancozeb was prepared for treatment as a suspension in dry ethanol; low dose 10 µg/L

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS and TEST SYSTEM:
The test water (100 mL/flask) was added to 250 mL borosilicate glass conical flasks with ground glass joints at the neck for attachment to the aeration and volatiles trapping system. The test water was stirred constantly throughout the filling of all the flasks.

Approximately 100 mL of the test water was dispensed into each flask. The flasks were treated as soon as practicable, i.e. one day, after filling to minimise any decline in biological activity relative to the natural system during the test. All flasks (24) were attached to an incubation system through which moistened air was passed, at a rate that allowed sufficient aeration of the headspace to maintain aerobic conditions and carry any volatiles formed into the trapping system. The passage of air was controlled by the use of flow restrictors. These ensure a uniform flow rate into each flask and allow individual flasks to be connected and disconnected without disrupting the flow through those remaining. Each flask was connected to a series of three traps, the first containing ethylene glycol and the second and third containing 2M potassium hydroxide.

Due to its very low solubility in organic solvents and instability in water mancozeb was prepared for treatment as a suspension in dry ethanol. Flasks containing the test water were each treated with 100 µL of the corresponding [14C]-treatment solution using a positive displacement pipette. The application rates achieved were 0.91 µg of mancozeb per flask for the 10 µg/L nominal dose level and 9.62 µg of mancozeb per flask for the 100 µg/L nominal dose level, giving actual dose levels of 9.1 and 96.2 µg/L respectively.

All sample, control and reference flasks (other than the zero-time samples) were incubated in the dark at 20 ± 2°C. Aerobic conditions in the water phase were maintained by the constant passage of moist air through the sample flasks and out through the trap solutions, and by the stirring of the water to facilitate mass transfer across the air/water interface.

At the time of sampling, flasks and their associated traps were transferred to an extraction system which used vacuum to draw air into the flasks and through the traps. Capillary flow restrictors were employed to control the flow of air. Once the flasks were attached to the system they were amended with 10 mL of methanol and 2 mL of formic acid and closed immediately. The stirring rate was then increased and the samples left on the trapping system for four hours. This procedure served to drive inorganic carbon out of the samples and into the KOH traps, to allow for the accurate quantification of 14CO2 within the samples and avoid losses during work-up which might otherwise have occurred

Sterile replicates were treated under a running laminar flow hood. The treatment solution used was intrinsically sterile due to its solvent content and was used without additional sterilisation.

SAMPLING:
For each of the two dose levels, duplicate flasks and their associated traps were removed for analysis at zero time and following 3, 7, 14, 21, 28, 35, 42, 49 and 60 days of incubation. On days 7 and 14 of the study duplicate positive control samples were also taken. Solvent controls were sampled on day 7 and the sterile controls were sampled at the end of the study on day 60.

REFERENCE SUBSTANCES:
The microbial activity of the test system was confirmed by conducting the aerobic mineralisation in surface water with control item benzoic acid at a concentration of 10 μg/L.

Reference standards including ethylene urea (EU), ethylene thiourea (ETU) and ethylenebisdiisothiocyanate sulfide (EBIS) were used for co-chromatography. Spray reagents were used to make the reference standards visible. A nitroprusside/ferricyanide reagent was used for the visualisation of EU, ETU and EBIS on the majority of plates and also yielded signals for hydantoin, glycine and glycinamide. Visualisation of reference items not containing amine groups e.g. ethylene glycol and glycolic acid required the careful use of chromosulphuric acid. ETU, EBIS and Jaffe’s Base were also visualised by fluorescence quenching under illumination at 254 nm.

Reference substance:

other: Glycine

Reference substance:

other: Oxalic acid

Reference substance:

other: Ethanolamine (EA)

Reference substance:

other: Mancozeb

Reference substance:

other: ethylene urea (EU)

Reference substance:

other: ethylene thiourea (ETU)

Reference substance:

other: Ethylenebisdiisothiocyanate sulphide (EBIS)

Reference substance:

other: chromosulfuric acid

Reference substance:

other: glycolic acid (GA)

Reference substance:

ethylene glycol

Reference substance:

benzoic acid, sodium salt

Compartment:

natural water: freshwater

Sampling date:

2015

% Recovery:

95.7

Remarks on result:

other: Overall material balance: High dose concentration 100 µg/L

Compartment:

natural water: freshwater

Sampling date:

2020

% Recovery:

95.2

Remarks on result:

other: Overall material balance (mean): Low dose concentration 10 µg/L

Parent/product:

parent

Compartment:

water

Key result

% Degr.:

91.6

Parameter:

radiochem. meas.

Sampling time:

3 d

Remarks on result:

other: Appied radioactivity parent compound; high dose (100 µg/L): 91.6 % on DAT 0 degradeted to 0 % on DAT 3

Parent/product:

parent

Compartment:

water

Key result

% Degr.:

87.5

Parameter:

radiochem. meas.

Sampling time:

3 d

Remarks on result:

other: Applied radioactivity parent compound; low dose (10 µg/L); 87.5% on DAT 0 degraded to 0 % on DAT 3

Key result

Compartment:

natural water: freshwater

DT50:

< 0.34 d

Type:

other: Single First-Order (SFO)

Temp.:

20 °C

Remarks on result:

other: high dose (100 µg/L)

Key result

Compartment:

natural water: freshwater

DT50:

< 0.36 d

Type:

other: Single First-Order (SFO)

Temp.:

20 °C

Remarks on result:

other: low dose (10 µg/L)

Mineralization rate (in CO2):

17.7 other: % on DAT 49; max level in low dose (10 µg/L)

Transformation products:

yes

No.:

Details on transformation products:

Please refer to the attached tables for the details reprensentation of the formation and decline of each metabolite for the low and high dose (10 µg/L / 100 µg/L).

Details on results:

At both dose levels ethylenethiourea (ETU) was the main metabolite present after DAT 3 of incubation comprising 22.3 % AR at the 10 µg/L dose level and 35.0 % AR at the 100 µg/L dose level. ETU levels then declined at both dose levels and were undetectable by day 21.
Declines in levels of ETU were accompanied by increases in levels of ethylene urea (EU). Levels of EU at the 10 µg/L dose level peaked at 30.4 % AR after 42 DAT of incubation before declining again to 23.9 % AR by DAT 60.
At the 100 µg/L dose level, levels of EU also rose initially (until DAT 14) but then showed no clearly discernible trend and accounted for 41.2 % AR on DAT 60. The data from DAT 49 departed from this general trend due to a single flask, which showed considerable degradation of EU and a corresponding elevation in levels of M13.

Ethylenebisdiisothiocyanate sulphide (EBIS) was found to be present at peak levels of ca. 6-7 % AR at both dose levels after DAT 3 of incubation. Levels of EBIS then declined rapidly in the samples from both dose rates giving mean levels of ca. 3 % AR on DAT 7. By DAT 14 EBIS was undetectable in samples from the 10 µg/L dose level and had decline to 1.7 % AR at the 100 µg/L dose level. EBIS was only present at levels exceeding 5 % AR for a single interval.

Metabolite M4, which was tentatively identified at Ethanolamine (EA) was present only transiently (3 and 7 DAT) at the 10 µg/L dose level but at the 100 µg/L dose level it increased to a peak of 15.4 % AR on DAT 14 before declining again to 4.3 % by DAT 35.

Metabolite M8, which was tentatively identified as glycolic acid (GA) was present at peak levels of 15.5 % AR in the 10 µg/L dose level samples after 28 DAT. Levels of GA in the samples from the 100 µg/L dose level were generally lower reaching a peak of 8.2 % AR after 21 DAT of incubation.

Metabolite M13, which was tentatively identified as ethylene glycol (EG) showed a pattern at the 10 µg/L dose level of increasing slowly to a maximum of 9.3 % AR on DAT 42 followed by a slow decline to 7.0 % AR by DAT 60. At the 100 µg/L dose level the levels increased to 12.2 % AR by DAT 21 and continued near this level for the remainder of the study. The only exception to this being the second replicate from the DAT 49 interval which showed a markedly different pattern of metabolism to the other replicate and to the preceding and following samples.

Of the remaining metabolites M2, M7 and M9 all exceeded 5 % for a single interval. Metabolite M7 showed similar migration to glycine and glycinamide using TLC method 1 but no attempts were made to confirm this further due to the low levels of the metabolite present. The remaining metabolites were minor and did not exceed an average (n=2) value of 5 % AR for any interval.

The activity present at the origin of the TLC plate was assigned the number M1 and showed average levels exceeding 10 % AR for the 10 µg/L dose level at the DAT 60 interval. M1 was found to reflect particulate matter in the samples, thought to potentially be labelled biomass or insoluble oxalate compounds.

Degradation kinetics of mancozeb under pelagic conditions

Dose Level	Kinetic	DT₅₀ (days)	DT₉₀ (days)	Chi2 (%)	t-test (-)	Visual
10 μg/L	SFO	<0.36	<1.2	-*	9.48E-04	Good
100 μg/L	SFO	<0.34	<1.1	-*	9.68E-15	Good

* No degrees of freedom to calculate due to rapid degradation and limited timepoints

Identification of metabolites

Metabolite code	Identity	Maximum level (%)
Metabolite code	Identity	10 µg/L	100 µg/L
M1	Oxalic acid	11.2	7.5
M4	Ethanolamine	5.5	15.4
M7	Glycine	5.3	5.2
M8	Glycolic acid	15.5	8.2
M9	EDA	6.8	-
M11	EU	30.4	41.2
M13	Ethylene glycol	9.3	24.7
M14	ETU	22.3	35.0
M16	EBIS	6.0	6.9

Composition of Radioactivity, Carsington Water, 10 μg/L Dose Level (as % of Applied Radioactivity)

Sampling Interval (Days)	M1	M2	M4 – EA	M7 - GLY	M8	M9 - EDA	M11 - EU	M13 - EG	M14 - ETU	M16 - EBIS	Parent	Minor Metabolites (sum)	Not Resolved by TLC/ impurities in treat. Sol.	% AR in Water
0	-	-	-	-	-	-	-	-	-	-	87.37	-	-	98.99
0	-	-	-	-	-	-	-	-	-	-	87.61	-	-	99.27
Mean	-	-	-	-	-	-	-	-	-	-	87.49	-	-	99.13
3	7.51	4.24	4.98	2.78	8.31	6.13	10.48	3.60	24.06	6.23	-	12.05	6.72*	97.08
3	7.37	3.60	4.19	2.43	8.76	7.39	10.01	3.14	20.46	5.69	-	9.56	10.85*	93.44
Mean	7.44	3.92	4.58	2.60	8.53	6.76	10.24	3.37	22.26	5.96	-	10.80	8.78*	95.26
7	7.70	3.12	6.19	4.51	14.80	3.26	21.67	8.01	4.06	-	-	5.64	16.26	95.21
7	2.58	7.45	4.84	6.12	9.82	4.69	14.94	4.74	8.32	6.20	-	10.33	6.98	87.02
Mean	5.14	5.29	5.51	5.32	12.31	3.97	18.31	6.37	6.19	3.10	-	7.98	11.62	91.11
14	3.18	0.00	-	4.11	11.90	3.85	27.99	5.31	1.67	-	-	6.67	24.08	88.75
14	3.10	1.97	-	3.36	18.46	4.69	27.69	4.72	-	-	-	7.72	13.49	85.19
Mean	3.14	0.98	-	3.74	15.18	4.27	27.84	5.01	0.83	-	-	7.19	18.79	86.97
21	6.36	0.87	-	3.29	10.50	3.68	25.41	7.34	-	-	-	5.70	16.42	79.58
21	6.14	0.91	-	2.77	11.04	4.11	23.48	5.90	-	-	-	7.24	16.19	77.78
Mean	6.25	0.89	-	3.03	10.77	3.90	24.45	6.62	-	-	-	6.47	16.31	78.68
28	7.92	1.02	-	2.92	14.06	3.06	17.04	6.24	-	2.52	-	3.05	20.39	78.23
28	5.93	0.78	-	2.68	10.34	1.81	26.70	8.31	-	-	-	3.26	20.06	79.87
Mean	6.93	0.90	-	2.80	15.46	2.43	21.87	7.28	-	1.26	-	3.15	20.22	79.05
35	5.66	0.75	-	4.38	9.56	4.22	24.74	9.03	-	-	-	7.39	8.81	74.54
35	4.86	0.00	-	4.97	11.11	1.80	30.34	6.33	-	-	-	8.84	9.27	77.51
Mean	5.26	0.38	-	4.67	10.33	3.01	27.54	7.68	-	-	-	8.11	9.04	76.02
42	5.36	0.84	-	3.97	6.86	0.80	31.98	11.71	-	1.06	-	9.84	5.20	77.64
42	9.61	0.73	-	0.97	11.15	3.53	28.75	6.96	-	1.02	-	4.66	3.18	70.56
Mean	7.49	0.78	-	2.47	9.01	2.16	30.37	9.33	-	1.04	-	7.25	4.19	74.10
49	9.85	0.66	-	1.14	10.55	2.94	29.58	8.34	-	-	-	1.77	12.63	77.46
49	7.41	1.03	-	0.90	13.54	1.69	22.42	8.80	-	-	-	3.86	12.42	72.08
Mean	8.63	0.84	-	1.02	12.05	2.31	26.00	8.57	-	-	-	2.81	12.53	74.77
60	13.33	2.22	-	5.21	15.67	2.81	19.56	6.56	-	-	-	1.44	14.02	80.84
60	8.97	0.00	-	-	13.61	-	28.17	7.42	0.54	-	-	4.05	9.65	72.41
Mean	11.15	1.11	-	2.61	14.64	1.41	23.86	6.99	0.27	-	-	2.75	11.83	76.62
60 Sterile	2.04	1.07	1.98	0.53	1.50	-	21.43	6.31	47.12	-	-	7.05	5.15	94.06
60 Sterile	1.99	1.53	2.19	0.70	1.43	-	22.64	6.21	46.72	-	-	7.24	8.23	98.86
Mean	2.01	1.30	2.09	0.61	1.47	-	22.03	6.26	46.92	-	-	7.14	6.69	96.46

* Values are the sum of a number of minor impurities in the treatment solution, the impurities were visible in HPLC analysis of the parent compound after derivatisation.

Compositon of Radioactivity, Carsington Water, 100 μg/L Dose Level (as % of Applied Radioactivity)

Sampling Interval (Days)	M1	M2	M4 - EA	M7 - GLY	M8 - GA	M10	M11 - EU	M13 - EG	M14 - ETU	M16 - EBIS	Parent	Minor Metabolites (Sum)	Not Resolved by TLC/ Impurities in Treat. Sol.	% AR in Water
0	-	-	-	-	-	-	-	-	-	-	90.74	-	7.48*	98.22
0	-	-	-	-	-	-	-	-	-	-	92.54	-	7.63*	100.17
Mean	-	-	-	-	-	-	-	-	-	-	91.64	-	7.56*	99.20
3	6.65	0.43	3.66	1.46	3.31	2.41	10.22	4.79	34.98	6.90	-	12.55	7.38	94.73
3	8.38	0.00	4.49	1.97	4.82	1.82	14.25	5.39	35.02	6.89	-	13.82	4.28	101.14
Mean	7.52	0.21	4.07	1.72	4.07	2.11	12.24	5.09	35.00	6.89	-	13.18	5.83	97.94
7	5.13	5.64	3.29	5.17	1.99	1.97	17.98	8.67	22.63	3.46	-	8.31	10.29	94.52
7	6.83	6.77	3.83	5.13	1.32	2.12	18.58	8.74	22.44	3.48	-	9.23	8.02	96.51
Mean	5.98	6.20	3.56	5.15	1.66	2.04	18.28	8.71	22.53	3.47	-	8.77	9.16	95.51
14	3.70	1.89	13.70	2.04	7.02	-	38.25	12.07	3.00	1.81	-	5.42	6.98	95.84
14	2.75	0.50	17.13	-	7.48	5.99	42.11	1.29	6.13	1.57	-	4.67	5.06	94.67
Mean	3.23	1.19	15.41	1.02	7.25	3.00	40.18	6.68	4.56	1.69	-	5.04	6.02	95.26
21	4.02	0.40	9.60	2.78	7.68	-	37.53	13.25	-	1.01	-	10.15	4.87	91.29
21	4.06	1.13	13.44	3.04	8.76	-	34.67	11.18	-	1.13	-	5.67	10.35	93.44
Mean	4.04	0.77	11.52	2.91	8.22	-	36.10	12.22	-	1.07	-	7.91	7.61	92.36
28	3.54	0.90	9.54	2.03	6.60	-	41.46	12.08	-	-	-	8.02	8.13	92.30
28	4.07	1.34	16.47	2.58	7.12	-	38.18	11.01	-	-	-	6.66	8.26	95.69
Mean	3.80	1.12	13.00	2.31	6.86	-	39.82	11.55	-	-	-	7.34	8.19	94.00
35	3.70	0.61	6.31	2.28	6.44	-	39.80	14.35	-	-	-	9.97	7.53	90.99
35	7.10	1.29	2.33	2.84	5.92	-	36.12	13.34	-	-	-	8.48	6.04	83.47
Mean	5.40	0.95	4.32	2.56	6.18	-	37.96	13.84	-	-	-	9.23	6.78	87.23
42	7.94	0.91	-	1.59	5.57	-	37.37	12.30	-	-	-	2.52	12.46	80.64
42	3.55	1.56	9.71	1.17	4.80	-	35.21	12.42	-	1.23	-	5.29	9.28	84.22
Mean	5.74	1.23	4.86	1.38	5.19	-	36.29	12.36	-	0.61	-	3.91	10.87	82.43
49	3.66	1.27	6.33	2.11	4.91	1.37	41.28	13.13	-	-	-	3.06	8.35	85.46
49	6.30	1.65	2.81	2.89	5.56	1.81	15.73	36.26	-	0.70	-	5.44	4.41	83.56
Mean	4.98	1.46	4.57	2.50	5.24	1.59	28.50	24.69	-	0.35	-	4.25	6.38	84.51
60	4.53	0.75	4.60	2.29	4.09	-	39.87	12.52	-	-	-	8.32	7.15	84.14
60	3.74	0.97	5.56	1.84	5.57	-	42.57	13.48	-	-	-	5.83	7.39	86.97
Mean	4.14	0.86	5.08	2.07	4.83	-	41.22	13.00	-	-	-	7.07	7.27	85.55
60 Sterile	1.07	0.55	1.55	0.59	1.56	-	25.73	7.67	49.56	-	-	5.46	4.02	97.75
60 Sterile	1.37	0.45	1.40	0.60	1.30	-	25.11	7.58	52.62	-	-	4.13	3.51	98.07
Mean	1.22	0.50	1.48	0.59	1.43	-	25.42	7.63	51.09	-	-	4.80	3.76	97.91

* Values are the sum of a number of minor impurities in the treatment solution, the impurities were visible in HPLC analysis of the parent compound after derivatisation.

Validity criteria fulfilled:

yes

Conclusions:

[14C]-mancozeb was found to degrade rapidly (DT50 of < 0.5d) in a system consisting of natural water incubated in the dark at 20 ± 2° C. The degradation of Mancozeb resulted in the formation of a large number of metabolites, principally ETU and EU, but with significant levels of other metabolites; two of which were tentatively identified as ethanolamine and ethylene glycol and a third which was identified as glycolic acid. Ethylenebisdiisothiocyanate sulphide (EBIS) was also detected as a minor metabolite. Further minor metabolites which were tentatively identified were ethylene diamine and glycine/glycinamide. An additional metabolite tentatively identified as N-formyl ethylenediamine was also found to be present. Significant mineralisation of Mancozeb occurred at both dose levels, with the maximum level of mineralisation occurring at the 10 µg/L dose level (17.1% AR in traps, DAT 49).

Executive summary:

The summary below taken from the updated RAR Volume 3 CA B8 version December 2018.

The time course and concentration dependency of the degradation of [¹⁴C]-mancozeb was investigated under aerobic conditions in a “pelagic” test system at 20 ± 2°C in the dark for a period of 61 days. The study was carried out using water samples from Carsington Water, which is a ca 300 hectare reservoir which stores water pumped from the river Derwent at Ambergate and also receives smaller quantities of water draining off grassland surrounding the reservoir.

The test water (100 mL/flask) was added to 250 mL borosilicate glass conical flasks with ground glass joints at the neck for attachment to the aeration and volatiles trapping system. The flasks were treated as soon as practicable, i.e. one day, after filling to minimise any decline in biological activity relative to the natural system during the test. The redox potential of the water in control flasks was measured at regular intervals during the incubation. The pH and dissolved oxygen content of the water was also measured. Each flask was connected to a series of three traps, the first containing ethylene glycol and the second and third containing 2M potassium hydroxide.

The test item was applied at two nominal dose levels of 10 and 100 μg/L, to allow the concentration dependence of the rate of any degradation observed, to be examined.

Due to its very low solubility in organic solvents and instability in water Mancozeb was prepared for treatment as a suspension in dry ethanol (dried over anhydrous magnesium sulphate). The same treatment solutions were used for the sterile controls and were considered to be intrinsically sterile due to their solvent content. Initially a stock suspension was prepared by weighing out the test item and adding the solvent followed by sonication to disperse the test item. Small glass stir bars were used to maintain the homogeneity of stock and treatment suspensions while in use.

Four flasks per dose level (two replicates plus two spares) were prepared as sterile controls to enable differentiation between biotic and abiotic degradation of the test item.

Positive controls were used during the study to verify that the test water showed a good level of biological activity. These were treated with [Phenyl-U-¹⁴C]-benzoic acid at a nominal dose rate of 10 μg/L. Benzoic acid is known to mineralize rapidly in most natural waters. Solvent controls were prepared in an identical fashion except for the addition of the same volume of dry ethanol used in the treatment of samples treated with the test item.

All sample, control and reference flasks (other than the zero-time samples) were incubated in the dark at 20 ± 2°C. Aerobic conditions in the water phase were maintained by the constant passage of moist air through the sample flasks and out through the trap solutions, and by the stirring of the water to facilitate mass transfer across the air/water interface. For each of the two dose levels, duplicate flasks and their associated traps were removed for analysis at zero time and following 3, 7, 14, 21, 28, 35, 42, 49 and 60 days of incubation. On days 7 and 14 of the study duplicate positive control samples were also taken. Solvent controls were sampled on day 7 and the sterile controls were sampled at the end of the study on day 60.

At the time of sampling, flasks and their associated traps were transferred to an extraction system which used vacuum to draw air into the flasks and through the traps. Capillary flow restrictors were employed to control the flow of air. Once the flasks were attached to the system they were amended with 10 mL of methanol and 2 mL of formic acid and closed immediately. The stirring rate was then increased and the samples left on the trapping system for four hours. This procedure served to drive inorganic carbon out of the samples and into the KOH traps, to allow for the accurate quantification of ¹⁴CO₂ within the samples and avoid losses during work-up which might otherwise have occurred

The LOQ for the TLC method was 0.42% AR for the 100 mg/L dose level and 0.56% AR for the 10 mg/L dose level. At the lower dose level plates were exposed for a longer period of time and a larger volume of sample spotted.

The treatment suspensions for the 10 mg/L and the 100 mg/L dose level were analysed by HPLC after decomplexation using EDTA and derivatisation of the resulting EBDC with methyl iodide to produce a well retained product presumed to be dimethyl-EBDC. The identity of the EBDC derivative was confirmed with co-chromatography against the unlabelled Mancozeb reference item after derivatisation with the same procedure. The mean of two HPLC analyses of the 100 mg/L dose level treatment suspension after the first and second treatments was 92.38 % (this is the figure reported as the overall radiochemical purity for the study. The treatment suspension for the 10 mg/L dose level was analysed after the second treatment yielding a purity of 88.26% data not shown), this value is taken as a worst case value for the purity of the lower dose treatment solution at the time of treatment. The radiopurity of the ¹⁴C-benzoic acid treatment solution, determined as the mean of analyses before and after treatment, was 98.9%.

The mean application rates of [¹⁴C]-Mancozeb to the test vessels for the 10 and 100 mg/L dose levels were 0.91 and 9.62 mg/flask respectively which correspond to actual concentrations in the test vessels of 9.1 and 96.2 mg/L.

The pH of the water in the reference flasks averaged 6.9 (range 6.1 to 7.9). The oxygen saturation of the water in the flasks averaged 94% (range 78-94%), while the redox potential averaged +212 mV (range +66 to +385 mV).

These results showed that the test water remained aerobic and within the environmentally relevant pH range throughout the study.

The overall material balances were good for both test-item dose levels with mean values of 95.2% AR for the 10 mg/L dose level and 95.7% AR for the 100 mg/L dose level. With a single exception (flask 16 day 42, 10 mg/L dose level, 87.9% AR) individual recoveries were all within the range of 90–110%.

The positive control flasks (days 7, 14) showed recoveries of 92.1 and 91.0% AR respectively, mostly in the form of ¹⁴CO_2.The recovery in the solvent control vessels on day 7 was similar (86.6% AR).

Mean (n=2) levels of volatiles were greater for the 10 mg/L dose level of the test item as compared to the 100 mg/L dose level. At the lower dose level total volatiles reached a maximum value of 17.1% AR in the day 49 samples with the value on day 60 being essentially the same (16.8% AR). In the samples from 100 mg/L dose level the maximum level of total volatiles also occurred on day 49 (9.1% AR), but the overall levels were essentially constant from days 42 to 60. The positive control samples showed rapid mineralisation of the ¹⁴C-benzoic acid with mean (n=2) levels of 81.6% and 84.3% AR being recovered in the volatile traps.

It was confirmed by precipitation of ¹⁴CO₂in the form of barium carbonate that ¹⁴CO₂was the only labelled product present in the volatiles traps. The solvent control samples showed a similar pattern of activity with 76.6% AR being recovered from the volatile traps after 7 days with no significant activity present in the ethylene glycol traps, thus the solvent used in treatment of the study did not display a significant effect on the activity of the microorganisms within the test water. Furthermore the water was shown to display sufficient biological activity for the study.

Mancozeb rapidly dissipated from the water due to degradation, with no residues >LOD remaining by day 3.
The rapid degradation of mancozeb was accompanied by the formation of identified metabolites and CO₂ (17.1%). DT₅₀ values (decline from maximum) for ETU are estimated as 2.2 and 4.5 days for the 10 mg/L and 100 mg/L systems respectively.

[¹⁴C]-mancozeb was found to degrade rapidly (DT₅₀ of < 0.5d) in a system consisting of natural water incubated in the dark at 20 ± 2^oC. The degradation of Mancozeb resulted in the formation of a large number of metabolites, principally ETU and EU, but with significant levels of other metabolites which were tentatively identified as ethanolamine, ethylene glycol and glycolic acid. Ethylenebisdiisothiocyanate sulphide (EBIS) was also detected as a minor metabolite. Significant mineralisation of Mancozeb occurred at both dose levels with the maximum level of mineralisation occurring at the 10 µg/L dose level (17.1% AR in traps, day 49).

Reference 2

Endpoint:

biodegradation in water and sediment: simulation testing, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Start of experiments was 1994-03-18 and ended on 1994-08-08. Study completition date: 1995-05-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: BBA Richtlinien für die Prüfung von Pflanzenschutzmitteln in Zulassungsverfahren Teil IV: 5-1, December 1990

Version / remarks:

1990

Deviations:

Principles of method if other than guideline:

and under consideration of: Pesticide Assessment Guideline, Subdivision 0, Residue Chemistry, Section 171-4 (a) (2), U.S. Environmental Protection Agency, October 1982.

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment

Details on source and properties of surface water:

Details on source and properties of sediment:

River water/sediment from the river Rhine (Mumpf Zeltplatz, Aargau, Switzerland).
Pond water/sediment (Froschteich, Möhlin, Aargau, Switzerland).

Date of Sampling: February 4, 1994

The sediment was sampled from the top 5 - 10 cm. Water and sediment samples were transported frozen to the laboratory in sealed containers
-River sediment:
pH 6.85
Redox potential (mV) -105
OC (g C/100g dry sediment) 1.35
Biomass (mg microb. C/100g dry sed.) 109.7
CEC (mVal N/100g dry sed) 2.77
USDA nomenclature sand
Clay (% < 2µm) 7.0
Silt (% 2-50 µm) 11.6
Sand (% >50 µm) 81.4

-Pond sediment:
pH 6.61
Redox potential (mV) -112
OC (g C/100g dry sediment) 5.03
Biomass (mg microb. C/100g dry sed.) 330.3
CEC (mVal N/100g dry sed) 7.05
USDA nomenclature loam
Clay (% < 2µm) 5.0
Silt (% 2-50 µm) 35.8
Sand (% >50 µm) 59.2

Duration of test (contact time):

> 0 - < 105 d

Initial conc.:

ca. 30.1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

Unlabelled test article, radio labelled test article [14C]-Mancozeb and reference compounds Ethylene bis isothiocyanate sulphide (EBIS), Ethylene thiourea (ETU), Ethyleneurea (EU), Ethylene thiuram sulphide (ETD), Hydantoin (HYD), Jaffe's base, Glycine, 2-imidazoline, Sulphur were used. The specifications of the 2 test articles are: Mancozeb, purity 88.5%; radiolabelled Mancozeb radiopurity: 90.9%, specific activity: 20.3 mCi/mmol (76.52 µCi/mg)
Water was sampled to a depth of 10 - 30 cm and the sediment was sampled from the top 5 - 10 cm of each system. Water and sediment samples were transported frozen to the laboratory in sealed containers. After sieving at room temperature, they are stored at 4°C until their establishment in metabolism flasks.
Two different systems were used: River Water/Sediment from the river Rhine (Mumpf Zeltplatz, Aargau, Switzerland) and Pond water/Sediment (Froschteich, Möhlin, Aargau, Switzerland). Equilibration of the 2 systems was allowed for 3 weeks. The test was conducted at 20 ± 1 °C in the dark

Compartment:

natural water / sediment

% Recovery:

93.8

St. dev.:

Remarks on result:

other: pond system

Compartment:

natural water / sediment

% Recovery:

95.2

St. dev.:

2.8

Remarks on result:

other: river system

Key result

Compartment:

water

DT50:

< 1 d

Type:

other: Single first order (SFO)

Temp.:

20 °C

Remarks on result:

other: pond system

Key result

Compartment:

water

DT50:

< 1 d

Type:

other: Single first order (SFO)

Temp.:

20 °C

Remarks on result:

other: river system

Other kinetic parameters:

other: A re-evaluation of DT50 values according to FOCUS (2006) was done by Hardy, I (2015)

Transformation products:

yes

No.:

Details on transformation products:

The main degradation occurred in the water phase of the systems. Mancozeb quickly degraded in a transient compound EBIS, and thereafter to ETU, which is the most stable compound. ETU is totally converted to EU in the water phase. After EU, mainly carbon dioxide was found.

Aerobic conditions and anaerobic conditions were present in the water phase and in the sediment phase, respectively, of both test systems (see table below for results).

RIVER	Incubation time (days)
SYSTEM	0	0.25	1	2	7	14	30	59	105
Water	96.5	84.0	69.2	60.3	46.2	32.6	28.6	8.0	3.2
Sediment extractable	0.5	7.4	14.8	21.1	20.6	23.1	17.6	7.6	3.8
Sediment non-extractable	1.2	6.8	12.9	15.3	26.7	34.2	41.1	43.0	39.5
Sediment total	1.7	14.2	27.7	36.4	47.3	57.3	58.7	50.6	43.3
Volatiles	-	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1
¹⁴C-CO²	-	< 0.1	< 0.1	< 0.1	0.6	2.9	8.7	31.5	47.1
Total (Mass balance)	98.2	98.2	96.9	96.7	94.1	92.7	96.1	90.2	93.6
POND	Incubation time (days)
SYSTEM	0	0.25	1	2	7	14	30	59	105
Water	95.7	89.0	71.1	61.7	44.7	46.6	34.7	31.3	18.2
Sediment extractable	0.4	4.4	11.3	13.7	19.3	19.7	19.9	15.7	12.5
Sediment non-extractable	2.2	5.0	9.0	18.0	28.2	25.3	35.8	37.7	43.6
Sediment total	2.6	9.5	20.3	31.7	47.5	44.9	55.7	53.4	56.0
Volatiles	-	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1	< 0.1
¹⁴C-CO₂	-	< 0.1	< 0.1	< 0.1	0.4	0.9	2.9	7.6	17.6
Total (Mass balance)	98.2	98.5	91.4	93.5	92.6	92.4	93.3	92.3	91.8

The total average recoveries for the whole study were 95.2 ± 2.8 % for river and 93.8 ± 3.0 % for pond systems.

The study of the distribution of the radioactivity in the compartments showed a decrease of the radioactivity in the water phase during the course of the study. In the sediment phase, the amount of extractable radioactivity is low but reached a maximum of 23.1 % of initial radioactivity after 14 and 19.9% after 30 days in the river and the pond system, respectively. The amount of bound radioactivity continuously increased until day 59 (43% and 37.7% in river and pond system, respectively). In the river system it decreased thereafter (39.5% at day 105) while in the pond system it continued to increase (43.6% at day 105). More than 50% of the parent Mancozeb degraded within the first 6 hours of the experiment. Besides the parent compound, 9 radioactive fractions were found. EBIS that was already present at the beginning (9.0%) increased up to 12.7% after 6 hours before decreasing. ETU was the most abundant metabolite detected in the first 2 days (max. 41.9%). Its amount decreased thereafter and is below 0.01 mg/l after 59 days. EU accounted for 4.5, 12.3, and 13.4% after 1, 7, and 14 days, respectively, before dropping very fast to 0.4%. Hydantoin was a minor metabolite accounting for a maximum amount after 7 and 14 days (8.6%). Four unknown metabolites were detected at low amount. As in the river water phase, Mancozeb quickly degraded. After day 2, only 6.4% were present. EBIS was detected until 6 hours amounting to 3.8%. ETU represented the main metabolite. It reached a maximum on day 1 (48.5%) and decreased down to 16.1 and 0.2% after 14 and 105 days incubation, respectively. EU was present throughout the study with a maximum on day 59 (23.4%). Hydantoin and 4 unknown metabolites were also detected at low amounts.

As in the river water phase, Mancozeb quickly degraded. After day 2, only 6.4% were present. EBIS was detected until 6 hours amounting to 3.8%. ETU represented the main metabolite. It reached a maximum on day 1 (48.5%) and decreased down to 16.1 and 0.2% after 14 and 105 days incubation, respectively. EU was present throughout the study with a maximum on day 59 (23.4%). Hydantoin and 4 unknown metabolites were also detected at low amounts. The table below presents the percentage of the different metabolites observed in water for both systems.

RIVER	Incubation time (days)
SYSTEM	0	0.25	1	2	7	14	30	59	105
Mancozeb	52.3	16.4	12.8	8.1	nd	nd	np	np	np
EBIS	9.0	12.7	8.8	4.3	nd	nd	nd	nd	nd
ETU	9.5	41.9	35.3	39.0	14.2	4.0	nd	0.1	nd
EU	nd	nd	4.5	7.4	12.3	13.4	22.5	2.5	0.4
Hydantoin	nd	nd	nd	nd	7.2	8.6	nd	0.1	0.1
Unknown 1	nd	nd	nd	nd	nd	nd	0.7	0.4	0.3
Unknown 2	nd	nd	nd	nd	4.1	1.9	nd	< 0.1	nd
Unknown 3	nd	nd	nd	nd	1.0	nd	nd	0.1	0.1
Unknown 4	nd	nd	nd	nd	1.5	1.2	nd	0.1	nd
POND	Incubation time (days)
SYSTEM	0	0.25	1	2	7	14	30	59	105
Mancozeb	51.9	43.1	7.1	6.4	nd	nd	np	np	np
EBIS	8.9	3.8	nd	nd	nd	nd	nd	nd	nd
ETU	9.4	32.0	48.5	46.0	20.6	16.1	6.8	0.1	0.2
EU	nd	nd	8.2	6.3	7.4	8.5	21.2	23.4	14.9
Hydantoin	nd	nd	nd	nd	4.5	5.7	nd	nd	nd
Unknown 1	nd	nd	nd	nd	nd	nd	1.7	1.3	0.9
Unknown 2	nd	nd	nd	nd	5.5	11.7	0.9	nd	nd
Unknown 3	nd	nd	nd	nd	0.4	0.2	nd	nd	nd
Unknown 4	nd	nd	nd	1.0	1.0	0.2	nd	nd	nd

nd: not detectable ; np: not performed

Mancozeb was not detected in the sediment. ETU was the most abundant metabolite in the sediment with a maximum after 2 days (6.3%). It is rapidly degraded and is not detectable after 59 days. EBIS reached a maximum concentration after 2 days (3.8%). The maximum amount of EU appeared at day 30 (7.8%). Hydantoin and 5 unknown metabolites were detected accounting for a maximum of 3%. The metabolic pattern in pond sediment is very similar to the one observed in river sediment. ETU is observed at level up to 6.6 % at day 14 and is further degraded to very low level (0.1 %) after 59 days.

EU was found in slightly higher quantity at the end of the incubation period. EBIS and UK2 were detected at slightly lower level than in the river sediment. The table below presents the percentage of the different metabolites observed in sediment for both systems.

RIVER	Incubation time (days)
SYSTEM	0	0.25	1	2	7	14	30	59	105
EBIS	np	np	3.0	3.8	2.6	2.2	1.1	0.6	np
ETU	np	np	2.8	6.3	4.2	4.8	1.6	nd	np
EU	nd	nd	0.5	1.3	4.1	3.9	7.8	1.0	nd
Hydantoin	nd	nd	0.3	0.4	2.5	3.0	0.1	np	np
Unknown 1	nd	nd	nd	nd	nd	nd	0.1	< 0.1	np
Unknown 2	nd	nd	0.9	2.7	2.8	2.1	1.1	0.2	np
Unknown 3	nd	nd	1.4	1.7	1.8	1.2	0.3	0.4	nd
Unknown 4	nd	nd	0.3	2.6	1.7	2.3	0.9	0.4	nd
Unknown 5	nd	nd	0.2	0.7	0.2	1.2	nd	nd	np
POND	Incubation time (days)
SYSTEM	0	0.25	1	2	7	14	30	59	105
EBIS	np	np	1.1	1.0	0.8	1.1	0.2	nd	nd
ETU	np	np	2.4	5.6	6.0	6.6	0.5	0.1	0.1
EU	np	np	0.2	1.0	3.0	2.7	9.1	8.7	8.0
Hydantoin	np	np	0.2	0.6	2.0	2.2	< 0.1	nd	nd
Unknown 1	np	np	nd	nd	nd	nd	0.6	0.6	0.5
Unknown 2	np	np	0.7	2.1	3.8	3.5	4.8	0.1	0.1
Unknown 3	np	np	0.7	1.2	1.2	3.1	0.5	0.2	0.1
Unknown 4	np	np	nd	0.9	1.3	1.4	0.6	0.3	0.5
Unknown 5	np	np	0.1	0.6	0.4	0.5	0.1	nd	nd

nd: not detectable ; np: not performed

The degradation rates constant (DT₅₀ and DT₉₀) were determined applying first-order reaction kinetics for Mancozeb, complexed Nabam, and ETU (see table below).

		River system			Pond system
		Water	Sediment	River system	Water	Sediment	Pond system
	Mancozeb	0.1	np	0.1	0.6	np	0.6
DT₅₀ (days)	Complexed nabam	0.2	np	0.2	0.1	np	0.1
	ETU	4.0	6.4	7.4	6.3	2.0	7.6
	Mancozeb	6.6	np	6.6	2.0	np	2.0
DT₉₀ (days)	Complexed nabam	2.0	np	2.0	1.3	np	1.3
	ETU	13.3	21.1	24.6	21.0	22.3	25.3

np: not present

The behaviour of mancozeb has been investigated in two water sediment studies under laboratory conditions at 20^oC [Müller-Kallert, 1994; Völkel, 1995]. A re-evaluation of DT50 values according to FOCUS (2006) was done by Hardy, IAJ (2015). Mancozeb data from these studies has been used in the kinetic modelling evaluations using KinGUI (v2.1).

The trigger and modelling endpoints for mancozeb recalculated according to FOCUS Degradation Kinetics requirements are summarised in the table below.

Table 1: Degradation parameters and modelling endpoints for mancozeb – Level P-I, total system and water phase

System	Approach	Chi² (%)	t-test (-)	DegT₅₀ (days)
River Rhine	HS DT₉₀/3.32	2.4	-	0.60
Ormalingen Pond	SFO	7.6	1.35E-06	0.29
River Rhine	SFO	5.6	0.000145	0.09
Froschteich Pond	SFO	3.8	4.82E-08	0.12
Geometric mean				0.21

Conclusions:

The summary below taken from the updated RAR Volume 3 CA B8 version December 2018.

The metabolism of [14C]-Mancozeb in aquatic systems was studied at 20 ± 1°C in the dark, in a River and a Pond aquatic system. The parent compound was rapidly broken down with half-lives of below 1 day. ETU presented degradation half-life of 6.3 and 7.5 days in river and pond system, respectively. Degradation mainly proceeded via hydrolysis resulting in short-lived metabolite EBIS. Simultaneously the transient metabolite ETU appeared before being oxidised to EU. In both systems, EU was further degraded to carbon dioxide. Even radioactivity bound to the sediment matrix was finally transformed to carbon dioxide.
No significant differences were observed for the degradation of Mancozeb in the river and the pond system. At the end of the incubation, in both systems, the metabolites formed non-extractable residues or were mineralised.

Executive summary:

In the present study, the degradation, distribution and metabolism of [¹⁴C]-MANCOZEB, i.e. the manganese ethylene bisdithiocarbamate (polymeric) complex with zinc salt, in equilibrated water/sediment systems was investigated.

The aquatic systems consisted of natural water and sediment from a River (Rhine) and from a Pond. The water phases were filtered through a 0.2 mm sieve. The uppermost 5-10 cm of the sediment were sampled and sieved through a 2 mm mesh. The test systems were acclimated to laboratory conditions (20 °C, in the dark) for 3 weeks before treatment. After this time, pH, redox potential and oxygen oncentration in water had reached constant values. Thereafter, the radiolabeled test substance was applied to the water surface at a concentration of about 0.794 mg/L corresponding to a field rate of about 2400 g a.i./ha (actual 2383 g/ha).

After treatment, the radioactivity in water decreased rapidly reaching values of 3.2% (River) and 18.2% (Pond) at the end of the study (day 105). The extractable radioactivity amounted to a maximum of 23.1% (River) on day 14 and 19.9% (Pond) on day 30. It decreased to 3.8% (River) and 12.5% (Pond) at the end of incubation (day 105). A steady increase was observed for the non-extractable radioactivity, reaching maximum values of 43.0% and 43.6% on day 59 and 105 in the River and Pond system, respectively. At the end of the study, the non-extractables decreased to 39.5% for River.

The amount of ¹⁴CO₂ evolved after 105 days of incubation accounted for a maximum of 47.1% (River) and 17.6% (Pond). The total radioactivity recoveries averaged to 95.2 ± 2.8% of the total applied radioactivity

for the River system and to 93.8 ± 3.0% for the Pond system.

MANCOZEB was mainly degraded by hydrolysis. It had broken down totally within two days. One of its stable metabolites was EBIS, i.e. 5.6 - Dihydro - 3H - imidazol [2,1-C]-1,2,4- dithiazole-3-thione. After application, this metabolite maximized to 12.7% (River) and 8.9% for Pond at the time of application. ETU appeared simultaneously with EBIS and formed a maximum on day 2. The maximum amounts detected were 45.3% (River) and 51.6% (Pond). ETU was completely converted to EU, i.e. 2-lmidazolidinone, thus demonstrating its transient character. EU reached its maximum of 30.3% on day 30 (River) and of 32.1% on day 59 (Pond). Hydantoin was detected at maximum amounts of 11.7% (River) and 8.0% (Pond) on day 14. Except for UK2, the concentrations of the unknown fractions UK1 to UK5 were below 0.050 mg/L or the fractions were not stable.

The unknown fraction UK1 was 0.007 mg/L in the River and 0.022 mg/L in the Pond system. UK2 was detected at its maximum between 2 and 30 days after application. It amounted to a maximum amount of 0.057 mg/i in the River and to 0.125 mg/l in the Pond system. UK3 amounted to a maximum of 0.023 mg/L in the River system and to 0.013 mg/L in the Pond system. UK4 was present from day 1 to 105. The maximum concentration was 0.029 mg/L at day 14 in the River system, whereas in Pond the concentrations achieved 0.019 mg/L only at day 14. UK5 was only detected in the sediment at low amounts and did not exceed 0.010 mg/L.

Reference 3

Endpoint:: biodegradation in water: sediment simulation testing
Type of information:: experimental study
Adequacy of study:: weight of evidence
Study period:: From July, 1992 to completition of experiments in December 1993. Study completed in February 1994.
Reliability:: 1 (reliable without restriction)
Rationale for reliability incl. deficiencies:: guideline study
Qualifier:: according to guideline
Guideline:: other: EPA Pesticides Assessment Guidelines, Subdivision O, Section 171-4(a)
Version / remarks:: 1982
Deviations:: no
Qualifier:: according to guideline
Guideline:: other: Richtlinie für die Prüfung von Pflanzenschutzmitteln in Zulassungsverfahren" Teil IV: 5.1
Version / remarks:: 1990
Deviations:: no
GLP compliance:: yes (incl. QA statement)
Radiolabelling:: yes
Oxygen conditions:: aerobic
Inoculum or test system:: natural water / sediment: freshwater
Details on source and properties of surface water:: Water was sampled down to a depth of 10 to 30 cm with a plastic container. The sampling site was located about 1 to 2 m from shore. Water as well as sediment were transported to RCC in sealed plastic containers. At RCC, the containers were kept at room temperature until sieving.

Date of Sampling: May 16, 1992
River Water/Sediment:
Source: Rhine, Mumpf Zeitplatz, Aargau, Switzerland.
Water phase River
Oxygen concentration (mg/L) 10.2
pH 7.72
redox potential (mV) +230

Pond Water/Sediment:
Source: Froschteich, Mohlin, Aargau, Switzerland
Water phase Pond
Oxygen concentration (mg/L) 7.7
pH 7.31
redox potential (mV) +210
Details on source and properties of sediment:: The sediment was sampled with a shovel from the top 5 to 10 cm. The sampling site was located about 1 to 2 m from shore. Water as well as sediment were transported to RCC in sealed plastic containers. At RCC, the containers were kept at room temperature until sieving.
River Water/Sediment:
Source: Rhine, Mumpf Zeitplatz, Aargau, Switzerland.
Sediment River
pH 7.6
Redox potential (mV) -174
OC (g C/100g dry sediment) 1.06
Biomass (mg microb. C/100g dry sed.) 43.1
CEC (mVal N/100g dry sed) 4.6
USDA nomenclature sand
Clay (% < 2µm) 12.1
Silt (% 2-50 µm) 4.9
Sand (% >50 µm) 83.0

Date of Sampling: May 16, 1992
Pond Water/Sediment:
Source: Froschteich, Mohlin, Aargau, Switzerland
Date of Sampling: May 16, 1992
Sediment Pond
pH 7.3
Redox potential (mV) -156
OC (g C/100g dry sediment) 1.59
Biomass (mg microb. C/100g dry sed.) 90.1
CEC (mVal N/100g dry sed) 17.8
USDA nomenclature loam
Clay (% < 2µm) 43.1
Silt (% 2-50 µm) 31.3
Sand (% >50 µm) 25.6
Duration of test (contact time):: > 0 - < 106 d
Initial conc.:: ca. 20 - ca. 25 other: ppm
Based on:: test mat.
Parameter followed for biodegradation estimation:: radiochem. meas.; test mat. analysis
Details on study design:: 14C- Dithane® M-45 with specific activity of 33.78 mCi/g and 96.67% radiopurity was used.
Dosing vehicle # 1 was comprised of 20 mg of 14C-mancozeb and 2.06 mg of non-labelled mancozeb in 1000 mL of water. The dosing vehicle concentration was measured by liquid scintillation counting (LSC) to be about 25 ppm. Dosing vehicle # 2, which was used to treat samples analysed by HPLC, was comprised of 10.91 mg of 14C-mancozeb in 500 mL water. Dosing vehicle concentration was measured to be about 20 ppm.
Two different systems were used: River Water/Sediment from the river Rhine (Mumpf Zeltplatz, Aargau, Switzerland) and Pond water/Sediment (Froschteich, Möhlin, Aargau, Switzerland). Equilibration of the 2 systems was allowed for 3 weeks. The test was conducted at 20 °C in the dark. Sediment and water from river (oxygenated) and pond (deoxygenated) were added to separate sets of flasks, each flask equipped with a series of volatile traps. These aquatic systems were incubated in an air-conditioned room at 20 °C in the dark. Ventilation with moistened air and gentle stirring were applied. Trapping solution samples were taken and analysed for 14C by liquid scintillation counting (LSC) at each sampling interval over the course of the experiment, with the sampled solution being replaced.
Compartment:: natural water / sediment
% Recovery:: 100.5
St. dev.:: 5.9
Remarks on result:: other: river system
Compartment:: natural water / sediment
% Recovery:: 103.5
St. dev.:: 5.1
Remarks on result:: other: pond system
: Key result
Compartment:: water
DT50:: <= 1.5 h
Type:: other: Single First Order (SFO)
Temp.:: 20 °C
Remarks on result:: other: pond water
: Key result
Compartment:: water
DT50:: < 1 h
Type:: other: Single First Order (SFO)
Temp.:: 20 °C
Remarks on result:: other: river water
Other kinetic parameters:: other: A re-evaluation of DT50 values according to FOCUS (2006) was done by Hardy, IAJ (2015)
Transformation products:: yes
No.:: #4
No.:: #3
No.:: #2
No.:: #1
Details on transformation products:: Water Phase: EBIS, ETU, EU
Sediment: ETU, EU
Conclusions:: The summary below taken from the updated RAR Volume 3 CA B8 version December 2018.
The results confirm that mancozeb hydrolyses rapidly in the water phase of an aquatic system. No mancozeb was detected in the sediment phase. In river water the DT50 of mancozeb is less than 1.0 hour. In pond water, the DT50 of mancozeb is 1.5 hour or less. The DT50 of ETU in river water is 11.1 days, and the DT90 36.7 days.
In river sediment, the ETU DT50 and DT90 are, respectively, 1.4 and 16.0 days. In pond water the same values are, respectively, 6.1 and 20.4 days. No ETU was detected in pond sediment.
Executive summary:: In the present study, the degradation, distribution and metabolism of [14C]-MANCOZEB, i.e. the manganese ethylenebis (dithiocarbamate) (polymeric) complex with zinc salt, in equilibrated water/sediment systems was investigated. The aquatic systems consisted of natural water and sediment from a river (Rhine) and from a pond. The water phases were filtered through a 0.2 mm sieve. The uppermost 5-10 cm of the sediment were sampled and sieved through a 2 mm mesh. The test systems were acclimated to laboratory conditions (20 ± 1°C, in the dark) for 3 weeks before treatment. After this time, pH values, redox potential and oxygen concentration in water had reached constant values. Thereafter, the radio labelled test substance was applied to the water surface at a target concentration of about 0.416 ppm corresponding to an application rate of 2400 g a.i./ha.
After treatment the radioactivity in the water decreased rapidly reaching values of 2.8 % (river) and 3.5 % (pond) at the end of the study (day 106). The extractable radioactivity was 21.4 % (river) on day 7 and 19.5 % (pond) on day 14. It decreased to 3.3 % (river) and 2.6 % (pond) to the end (day 106). A steady increase was observed for the non-extractable radioactivity, reaching maximum values of 43.0 % and 37.2 % on day 30. At the end of the study, the non-extractables decreased to 36.7% (river) and 35.4 % (pond). The total radioactivity recoveries averaged to 100.5 ± 5.9 % of the total applied radioactivity for the river system and to 103.5 ± 5.1 % for the pond system. MANCOZEB was mainly degraded by hydrolysis. It has broken down totally within 24 hours. The first stable product was EBIS, Le. 5.6 - Dihydro - 3H - imidazol [2,1-C]-1,2,4-dithiazol-3-thione. This metabolite maximized at 6 hours to 16.4 % (river) and immediately after application (pond) to 30.9 %. ETU appeared shortly after EBIS and formed a maximum on day 2. The maximum amounts were 33.6 % (river) and 47.5 % (pond). ETU was completely converted to EU, i.e. 2-lmidozolidone, thus demonstrating its transient character. EU reached its maximum of 30.0 % on day 7 (river) and of 43.5% on day 14 (pond). The Jaffe's Base was found on day 7 in river and on day 14 in both systems. The respective amounts were 3.3 % (river, day 7) and 4.7 % (pond, day 14). The concentrations of the unknown fractions
UK1 to UK4 were below 0.050 mg/L or the fractions were not stable:
The unknown fraction UK1 was below 50 µg/L in water or sediment. UK2 was only detected until 24h after application. UK3 dropped below 0.010 mg/L after day 2 (river and pond). UK 4 was present from day 1 to 60. The maximum concentration was 0.040 mg/L at 14 days in river system, whereas in pond the concentrations achieved 0.010 mg/L only at day 7.
The rate of degradation of MANCOZEB were very high in both aquatic systems. The DT₅₀ values were below one day. For ETU the DT₅₀ values were 11.1 days (river) and 6.7 days

Description of key information

The behaviour of mancozeb has been investigated in two water sediment studies under laboratory conditions at 20^oC [Müller-Kallert, 1994; Völkel, 1995]. A re-evaluation of DT50 values according to FOCUS (2006) was done by Hardy, I (2015). Mancozeb data from these studies has been used in the kinetic modelling evaluations using KinGUI (v2.1).

The trigger and modelling endpoints for mancozeb recalculated according to FOCUS Degradation Kinetics requirements are summarised in the table below.

Table 1: Degradation parameters and modelling endpoints for mancozeb – Level P-I, total system and water phase

System	Approach	Chi² (%)	t-test (-)	DegT₅₀ (days)
River Rhine	HS DT₉₀/3.32	2.4	-	0.60
Ormalingen Pond	SFO	7.6	1.35E-06	0.29
River Rhine	SFO	5.6	0.000145	0.09
Froschteich Pond	SFO	3.8	4.82E-08	0.12
Geometric mean				0.21

Key value for chemical safety assessment

Half-life in freshwater:: 0.21 d
at the temperature of:: 20 °C

Whole System

Half-life in whole system:: 0.21 d
at the temperature of:: 20 °C
Type of system:: fresh water and sediment

Additional information

Biodegradation in surface water

The test item was applied at two nominal dose levels of 10 and 100 μg/L, to allow the concentration dependence of the rate of any degradation observed, to be examined.

Four flasks per dose level (two replicates plus two spares) were prepared as sterile controls to enable differentiation between biotic and abiotic degradation of the test item.

These results showed that the test water remained aerobic and within the environmentally relevant pH range throughout the study.

Weight of Evidence on the biodegradation in water/sedimetn systems

The summary below taken from the updated RAR Volume 3 CA B8 version December 2018.

Müller-Kallert, 1994

In the present study, the degradation, distribution and metabolism of [14C]-MANCOZEB, i.e. the manganese ethylenebis (dithiocarbamate) (polymeric) complex with zinc salt, in equilibrated water/sediment systems was investigated. The aquatic systems consisted of natural water and sediment from a river (Rhine) and from a pond. The water phases were filtered through a 0.2 mm sieve. The uppermost 5-10 cm of the sediment were sampled and sieved through a 2 mm mesh. The test systems were acclimated to laboratory conditions (20 ± 1°C, in the dark) for 3 weeks before treatment. After this time, pH values, redox potential and oxygen concentration in water had reached constant values. Thereafter, the radio labelled test substance was applied to the water surface at a target concentration of about 0.416 ppm corresponding to an application rate of 2400 g a.i./ha.
After treatment the radioactivity in the water decreased rapidly reaching values of 2.8 % (river) and 3.5 % (pond) at the end of the study (day 106). The extractable radioactivity was 21.4 % (river) on day 7 and 19.5 % (pond) on day 14. It decreased to 3.3 % (river) and 2.6 % (pond) to the end (day 106). A steady increase was observed for the non-extractable radioactivity, reaching maximum values of 43.0 % and 37.2 % on day 30. At the end of the study, the non-extractables decreased to 36.7% (river) and 35.4 % (pond). The total radioactivity recoveries averaged to 100.5 ± 5.9 % of the total applied radioactivity for the river system and to 103.5 ± 5.1 % for the pond system. MANCOZEB was mainly degraded by hydrolysis. It has broken down totally within 24 hours. The first stable product was EBIS, Le. 5.6 - Dihydro - 3H - imidazol [2,1-C]-1,2,4-dithiazol-3-thione. This metabolite maximized at 6 hours to 16.4 % (river) and immediately after application (pond) to 30.9 %. ETU appeared shortly after EBIS and formed a maximum on day 2. The maximum amounts were 33.6 % (river) and 47.5 % (pond). ETU was completely converted to EU, i.e. 2-lmidozolidone, thus demonstrating its transient character. EU reached its maximum of 30.0 % on day 7 (river) and of 43.5% on day 14 (pond). The Jaffe's Base was found on day 7 in river and on day 14 in both systems. The respective amounts were 3.3 % (river, day 7) and 4.7 % (pond, day 14). The concentrations of the unknown fractions
UK1 to UK4 were below 0.050 mg/L or the fractions were not stable:
The unknown fraction UK1 was below 50 µg/L in water or sediment. UK2 was only detected until 24h after application. UK3 dropped below 0.010 mg/L after day 2 (river and pond). UK 4 was present from day 1 to 60. The maximum concentration was 0.040 mg/L at 14 days in river system, whereas in pond the concentrations achieved 0.010 mg/L only at day 7.
The rate of degradation of MANCOZEB were very high in both aquatic systems. The DT₅₀ values were below one day. For ETU the DT₅₀ values were 11.1 days (river) and 6.7 days

Völkel, 1995

The summary below taken from the updated RAR Volume 3 CA B8 version December 2018.

for the River system and to 93.8 ± 3.0% for the Pond system.

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Diss Factsheets

mancozeb (ISO); manganese ethylenebis(dithiocarbamate) (polymeric) complex with zinc salt

Biodegradation in water and sediment: simulation tests

Administrative data

Link to relevant study record(s)

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Description of key information

Key value for chemical safety assessment

Whole System

Additional information

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