N-butylbenzenesulphonamide

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:

2013-12-19 to 2014-04-04

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on source and properties of surface water:

- Details on collection: Water was taken from a natural, large open water body from Rhineland-Palatinate (67374 Hanhofen, Germany). Water was sampled from the top 5 cm to 10 cm. The water was transported in polyethylene containers to the laboratory.
- Storage conditions: in the dark under aeration at about 4°C
- Storage length: 5 days
- Temperature (°C) at time of collection: 5°C
- pH at time of collection: 7.80
- Oxygen concentration (mg/l) initial: 7.06 mg/l (below the water surface); 6.73 mg/l (water/sediment interface)
- Dissolved organic carbon (%): 10.5 mg/l
- BOD5: 8 mg/l
- Water filtered: yes
- Type and size of filter used: 0.1 mm sieve

Duration of test (contact time):

ca. 78 d

Initial conc.:

ca. 10 µg/L

Based on:

test mat.

Initial conc.:

ca. 95 µg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

radiochem. meas.

other: volatile organics

Details on study design:

TEST CONDITIONS
- Volume of test solution: 500 ml
- Composition of medium: natural water
- Solubilising agent: acetonitrile with a concentration below 0.1% of the amount of water
- Test temperature: 20 ±2°C
- pH: 8.06-8.52 (pH of the blanks)
- pH adjusted: no
- Continuous darkness: yes
- Mass balances were established at each sampling interval including the determination of the volatiles


TEST SYSTEM
- Culturing apparatus: 1000 mL all-glass metabolism flasks (inner diameter: 0.1 cm; surface: 80 cm²). During the test period vessels were moistened by an all-glass metabolism flask which was connected in front of the test flasks and which was filled with pure water.
- Number of culture flasks/concentration: duplicates
- Two different application rates (10 μg/L, respectively 95 μg/L) of radiolabelled test item were applied. Assuming a specific activity of 5.28 MBq/mg this corresponds to a spiked radioactivity of about 0.03 MBq respectively 0.25 MBq per vessel
- Method used to create aerobic conditions: constant bubbling of air through the water
- Measuring equipment: The radioactivity was quantified by liquid scintillation counting, characterised by normal phase and confirmed by reversed phase thin layer chromatography
- Details of trap for CO2 and volatile organics if used: Any CO2 generated in the flasks was trapped by two sodium hydroxide reservoirs. Any organic volatiles generated in the flasks were trapped by Tenax as an adsorbent.


SAMPLING
- Sampling frequency: at day 0, 7, 13, 19, 28, 43, 58 and 78
- Sample storage before analysis: no
- Other: Samples were analysed directly by LSC, immediately concentrated by rotary evaporation and analysed by TLC. Thereafter, samples and concentrated extracts were stored in a freezer at approx. -18°C.

CONTROL AND BLANK SYSTEM
- Abiotic sterile control: Solvent blank controls and two reference samples were spiked with 590 μL
solvent to monitor the influence of the solvent to the biodegradability

STATISTICAL METHODS:
Calculation of Half-Life Times and Best Fit:
The disappearance time (DT) of the test item was calculated according to the recommendations of EC document 9188/VI/97 rev. 8 (2000). The calculation of the rate constant and the initial concentration was performed using the software KinGUII (2011).

Reference substance:

benzoic acid, sodium salt

% Degr.:

< 1

Parameter:

CO2 evolution

Sampling time:

78 d

Remarks on result:

other: Amounts of <1 % AR were detected as CO2 in experiments with 10 and 95 μg/L, respectively. The amount of solved CO2 in the sodium hydroxide traps was negligible for both concentrations

Compartment:

natural water: freshwater

DT50:

ca. 858 d

St. dev.:

1.7

Type:

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

Temp.:

20 °C

Remarks on result:

other: at initial concentration of 10 μg/L

Compartment:

natural water: freshwater

DT50:

ca. 985 d

Type:

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

Temp.:

20 °C

Remarks on result:

other: at initial concentration of 95 μg/l

Transformation products:

no

Evaporation of parent compound:

no

Details on results:

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

MAJOR TRANSFORMATION PRODUCTS
- none

MINOR TRANSFORMATION PRODUCTS
- Only amounts <1% AR (applied radioactivity) were detected as CO2. The amount of solved CO2 in the sodium hydroxide traps was negligible. Organic volatiles were detected <1%

EXTRACTABLE RESIDUES
- % of applied amount at day 0: 99.5 % of the parent compound (for the 10 μg/ l solution) and 90.3% (for the 95 μg/ l solution)
- % of applied amount at end of study period: 99.9 % (for the 10 μg/ l solution) and 92.3% (for the 95 μg/ l solution)

MINERALISATION
- % of applied radioactivity present as CO2 at end of study: <1%

VOLATILIZATION
- % of the applied radioactivity present as volatile organics at end of study: <1%

STERILE TREATMENTS (if used)
- Transformation of the parent compound: The sterilized test samples were analyzed 34 days after treatment. The mean recovery of the parent in the water phase was 95%.
- Formation of transformation products: No transformation products could be observed. Therefore, hydrolysis rate was negligible

Results with reference substance:

The solvent containing reference samples were analysed 14 days after treatment.
The samples showed mean recoveries of mass of 90% - 95%. The mineralization
rate was 78% - 82%.
The system was biologically active and no influence of solvent of the activity of
the system could be observed.

Recovery results from the water phase are presented in table 1 (for 10 μg/l solutions) and table 2 (for 95 μg/l solutions). Mean recoveries are 92% - 99% (at 10 μg/l) and 92% - 100%. The mineralisation rate was negligible. Only amounts of <1% AR were detected as CO2. The amount of solved CO2 in the sodium hydroxide traps was negligible and is therefore not mentioned separately in the tables beneath. Organic volatiles were detected <1% AR.

 

Sampling interval [days]	0	7	13	19	28	43	58	78
Radioactivityin water phase mean Total Carbon dioxide   mean	99.5 99.4 99.5	95.1 96.5 95.8	97.1 90.1 93.6	95.9 97.6 96.8	92.8 91.7 92.3	90.9 93.1 92.0	96.7 94.8 95.8	93.4 93.2 93.3
	<1 1.0 1.0	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1
Organic volatiles   mean	n.a. n.a. n.a.	n.d. <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1
Recovery	99.5	95.2	97.4	96.1	93.3	91.2	97.2	93.7
	100.5	96.6	90.5	98.3	92.0	93.8	95.5	93.6
Mean Recovery	100.0	95.9	94.0	97.2	92.7	92.5	96.4	93.7

 

Table 1: Distribution of radioactivity between water phase, total carbon dioxide and organic volatiles (% of the applied radioactivity, mean of duplicate values) for the applied amount of 10 μg/l

n.d.: not detected; n.a.: not analysed

 

 

Samplinginterval [days]	0	7	13	19	28	43	58	78
Radioactivityinwaterphase mean	99.8 99.9 99.9	95.0 94.7 94.8	94.6 94.0 94.3	95.3 96.0 95.7	95.9 95.7 95.8	90.3 93.4 91.8	93.6 94.4 94.0	93.3 93.4 93.3
TotalCarbondioxide   mean	n.d. <1n.d.	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1
Organicvolatiles   mean	n.a. n.a. n.a.	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1	<1 <1 <1
MeanRecovery	100	94.9	94.4	95.8	95.8	91.8	94.0	93.4

 

Table 2: Distribution of radioactivity between water phase, total carbon dioxide and organic volatiles (% of the applied radioactivity, mean of duplicate values) for the applied amount of 95 μg/l

 

 

The parent compound [14C]-N-n-butylbenzene-sulphonamide could be determined with 92%-99% AR in 10 μg/l solutions (table 3) and in 95 μg/l solutions (table 4) during the incubation period. No metabolite could be observed.

 

 

WaterPhase:   samplinginterval[d]	0	7	13	19	28	43	58	78
	%AR
Parent	99.5	95.8	93.6	96.8	92.3	92.0	95.8	90.3
Total	99.5	95.8	93.6	96.8	92.3	92.0	95.8	90.3

 

Table 3: Distribution of the radioactivity of the water phase (% of the applied radioactivity, mean of duplicate values) for applied amount of 10 μg/L test item

 

 

WaterPhase:   samplinginterval[d]	0	7	13	19	28	43	58	78
	%AR
Parent	99.0	94.8	94.3	95.7	95.8	91.8	94.0	92.3
Total	99.9	94.8	94.3	95.7	95.8	91.8	94.0	92.3

 

 

Table 4: Distribution of radioactivity between water phase, total carbon dioxide and organic volatiles (% of the applied radioactivity, mean of duplicate values) for the applied amount of 95 μg/l

Validity criteria fulfilled:

yes

Conclusions:

N-n-butylbenzenesulphonamide is not biodegraded in the standard simulation test in surface water (OEDC 309).

Executive summary:

The objective of this study was to determine the degradation rate and degradation products of [14C]-N-n-butylbenzenesulphonamide in a natural aerobic surface water in the dark, according to the OECD 309 testing guideline. Two different concentrations (10 μg/L and 95 μg/L) were applied per system, corresponding to a spiked radioactivity of about 0.03 MBq, respectively 0.25 MBq in the water phase.

The DT50 values for [14C]-N-n-butylbenzenesulphonamide were determined to be 858 (10 μg/L) and 985 days (95 μg/L) in the water phases. Therefore, [14C]-N-nbutylbenzenesulphonamide is persistent. At both concentrations <1% AR of organic volatiles were trapped. The mineralisation rate was negligible. Only amounts of <1% AR were detected as CO2.

Description of key information

N-n-butylbenzenesulphonamide does not degrade in a simulation test with natural surface water, according to test guideline OECD 309. The half-life in freshwater is estimated to be 858 days.

Since the substance is considered to be persistent in water, the other compartments (soil and sediment) were not additionally tested.

Key value for chemical safety assessment

Half-life in freshwater:

858 d

at the temperature of:

20 °C

Additional information

The objective of this study was to determine the degradation rate and degradation products of [14C]-N-n-butylbenzenesulphonamide in a natural aerobic surface water in the dark, according to the OECD 309 testing guideline. Two different concentrations (10 μg/L and 95 μg/L) were applied per system,

corresponding to a spiked radioactivity of about 0.03 MBq, respectively 0.25 MBq in the water phase.

The mineralisation rate was negligible. The DT50 values for [14C]-N-n-butylbenzenesulphonamide were determined to be 858 days (10 μg/L) and 985 days (95 μg/L) in the water phases. Therefore, [14C]-N-nbutylbenzenesulphonamide is persistent. At both concentrations <1% AR of organic volatiles were trapped. Only amounts of <1% AR were detected as CO2.