Tosylchloramide sodium

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The study is performed according to CTB guideline section G.1.1. but compared to OECD 307 some details are missing. This is however not considered to have an impact on most essential conclusions on the stability of Chloramine T and its degradation product p-TSA in soil.

Qualifier:

according to guideline

Guideline:

other: CTB section H 4.1 (testing section G.1.1) , Wageningen, The Netherlands

Deviations:

yes

Remarks:

The amount of the known hydrolysis product of [14C] Chloramine-T trihydrate (p-toluenesuIfonamide) was about 15%. This purity is less than ≥95% as required by the Guideline.

Principles of method if other than guideline:

Test material was applied to sandy loam soil in order to study the route and rate of degradation and to humic sand soil (12.7% humidity) and low humic content (4.3 % humidity) sand soil to study the rate of degradation. The soils were incubated under aerobic conditions in the dark at 20 °C. Application rate was 3 mg/kg on a dry soil basis. For the route of degradation at days 0, 7, 14 28, 56 and 100 CO2 evolution, (methanol) extractable radioactivity in the solids, bound residues and distribution of radioactivity between parent compound and metabolites (by HPLC) was measured. For the rate of degradation only the extractable radioactivity in the solids and distribution of radioactivity was measured.

GLP compliance:

yes

Test type:

laboratory

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

other: CTB 1,2,3

Year:

1993

Duration:

100 d

Initial conc.:

2.8 mg/kg soil d.w.

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

other: (methanol) extractable radioactivity in the solids, bound residues and distribution of radioactivity between parent compounds and metabolite(s) by HPLC.

Temp.:

20 °C

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Soil condition: air dried
- Pretreatment: The moisture content of the soils was adjusted to 0.32 bar moisture pressure (ie. 12.7% for the sandy loam soil and the hurnic sand soil, and 4.3% for the low humic content sand soil). Subsequently, the soils were stored at 20 ± 2 °C for 5 weeks to restore microbial activity. During the last day of the preincubation the soils were allowed to evaporate about 0.5 g of water per 50 g weight.
- Soil (g/replicate): 50 g dw
- No. of replication treatments: Twelve flasks were prepared; two for each sampling time
- Test apparatus (Type/material/volume): Glass conical flask, 250 or 300 mL
- Details of traps for CO2 and organic volatile, if any: soda lime CO2 absorption trap


Test material application:
[14C]Halamid was dissolved in 1 mL ethanol and 200 µL was pipetted into a vial. The ethanol was evaporated by a stream of air, and a total amount of 33 mL ultrapure water (pH adjusted to 8 with NaOH) was added. An aliquot of 0.5 mL of test solution (that is 128.542 kBq and 0.139 mg) was added to each test flask, resulting in a final test substance concentration of 2.8 mg/kg.

Any indication of the test material adsorbing to the walls of the test apparatus: no

Experimental conditions (in addition to defined fields)
- Moisture maintenance method: After 4, 6, 8 and 12 weeks ultrapure water was added to the flasks to compensate for evaporation
- Continuous darkness: Yes


SAMPLING DETAILS
- Sampling intervals: after 0, 7, 14, 28, 56 and 100 days the content of the flasks was analyzed
- Sampling method for soil samples: The soil samples were transferred to plastic bottles, and the test flasks were rinsed with 100 ml methanol which was then added to the soils. After shaking the pIastic bottles for about 5 minutes they were centrifuged for about 5 minutes. The methanol layer was decanted and after measuring its volume, the amount of radioactivity was determined by adding one mI samples to dupIicate scintillation vials containing 5 mI of UItima Gold. The extraction of the soil samples with 100 ml aliquots of methanol was repeated until the radioactivity in the extract was less than 3% of the initial radioactivity.
The extracts were pooled and stored frozen until they were concentrated to appropriate volumes by means of a rotary evaporator. The concentrated extracts were stored frozen pending analysis; with the exception of the extracts obtained after 100 days of incubation, which were not analysed further.

Key result

DT50:

< 1 d

Type:

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

Remarks on result:

other: DT90: < 1 day(s)

Transformation products:

yes

No.:

#1

Evaporation of parent compound:

no

Volatile metabolites:

no

Details on results:

The study of the route and rate of degradation of [14C]Chloramine-T trihydrate was carried out in sandy loam soil. The amount of radiolabelled carbon dioxide increased to about 48% of the initial radioactivity at the end of the test (100 days). The amount of extractable radioactivity (i.e. parent compound and metabolite(s)) decreased from 95% of the initial value at the start to 9% after 100 days. The bound residue increased from about 5% at the start of the experiment to a maximum value of about 36% at the end of the test. This means that it can be assumed that at least 90% of the added Chloramine-T trihydrate and transformation product(s) have been mineralised or converted into microbial biomass within the test period.
The amount of extractable radioactivity in the low humic content sand soil decreased slowly from about 94% at the beginning to 76% after 28 days, and then it decreased very rapidly to 4% after 56 days and 2% after 100 days. In the humic sand soil, the extractable radioactivity in the soil decreased from about 95% at the beginning to 39% at the end of the test (after 100 days).
Since [14C]Chloramine-T trihydrate is very rapidly (<< 1 day DT50 and DT90) converted to p-toluenesulfonamide DT50 and DT90 were estimated for p-toluenesulfonamide.
The degradation of p-toluenesulfonamide in sandy loam and humic sand soil follows approximately the expected first order reaction, while the degradation in low humic content sand soil follows a completely different pattern with a rapid degradation phase between 28 and 56 days. A rapid degradation of Chloramine-T trihydrate/p-toluenesulfonamide has also been observed in a ready biodegradation test amounting to 80% degradation in one week (Blok, J. 1982). There is no simple explanation for the difference in degradation pattern.

Since [14C]Chloramine-T trihydrate is very rapidly (<< 1 day DT₅₀and DT₉₀) converted to p-toluenesulfonamide DT₅₀ and DT₉₀ were estimated for p-toluenesulfonamide.

	DT50	DT90
Mineralization sandy loam soil*	102	183
Loss of parent compound sandy loam soil**	30	110
Loss of parent compound humic sand soil**	68	249
Loss of parent compound low humic content sand soil***	28	56
* best described by zero order function ** best described by first order function *** no reasonable fit, estimated values

Conclusions:

The recovery ranged from 92% to 100% of the initial radioactivity, and is within the range specified by the guideline.
Tosylchloramide sodium, trihydrate is a strong oxidizing agent in aqueous solution and when brought into contact with organic matter (soil) it reacts and leaves p-tolunenesulfonamide as the only detectable transformation product. The rate and route of p-toluenesulfonamide biodegradation depends on the soil type. But in each tested soil type p-toluenesulfonamide is totally mineralised.

Executive summary:

The metabolism and rate of degradation of [14C]Tosylchloramide sodium, trihydrate in three soils was determined according to the guidelines of the Dutch Board for Authorization of Pesticides and in compliance with the OECD Principles of Good Laboratory Practice (GLP).

In a laboratory study [14C]Tosylchloramide sodium, trihydrate was applied to a sandy loam soil in order to study the route and rate of degradation and to a humic sand soil and a low humic content sand soil to study the rate of degradation. The soils were incubated under aerobic conditions in the dark at 20 ± 2 °C . The application rate was 3 mg/kg on dry soil basis. For the route of degradation, the following parameters were determined after sampling times of 0,7, 14, 28, 56 and 100 days: C02 evoIution, (methanol) extractable radioactivity in the solids, bound residues and distribution of radioactivity between parent compound and rnetabolite(s) by HPLC (with the exception of the extracts obtained after I00 days). For the rate of degradation, only the extractable radioactivity in the solids and the distribution of radioactivity between parent compound and metabolite(s) was determined.

In the sandy loam soil, the evolved carbon dioxide amounted to about 48% of the initial radioactivity at the end of the test (100 days). The amount of methanol extractable radioactivity decreased from 95% at the start of the test to about 9% after 100 days. This means that it can be assumed that at least 90% of the added [14C]Tosylchloramide sodium, trihydrate and transformation product(s) have been mineralised or converted into microbial biomass within the test period. Bound residue increased from about 5% at the start of the test to 36% at the end of the test. The recovery ranged from 92% to 100% of the initial radioactivity.

In the humic sand soil, the amount of methanol extractable radioactivity decreased from about 95% at the start of the test to 39% after 100 days of incubation.

In the low humic content sand soil, the methanol extractable radioactivity decreased gradually from 94% to 76% after 28 days, and then decreased rapidly to 4% after 56 days and 2% after 100 days.

Of the soils used in this test, the low humic content sand soil contained the lowest amount of biomass, organic matter, nitrogen and day. Up to 28 days incubation there was a rough relationship between active biomass and the degree of degradation.

Concentrated soil extracts were analysed using HPLC with the following conditions: a Hypersil ODS column (100 x 3 mm) with a methanol:ultrapure water (pH adjusted to 2.5 with phosphoric acid) mobile phase was used. The flow rate was 0.8 ml/min, and sample volumes were 100 µl. The retention time of [14C]Tosylchloramide sodium, trihydrate was approximately 4 minutes and the retention time of its known

hydrolysis product p-toluenesulfonarnie was approximately 2 minutes.

The results of the analyses showed that [14C]Tosylchloramide sodium, trihydrate was only detected in one replicate of the sandy loam soil at the beginning of the test. [14C]Tosylchloramide sodium, trihydrate is almost instantly hydrolysed to p-toluenesulfonamide when added to the soils. The best estimate for DT50 and DT90 values (time to reach 50% and 90% degradation) for [14C]Tosylchloramide sodium, trihydrate is <<l day.

As [14C]Tosylchloramide sodium, trihydrate was almost instantly converted to p-toluenesulfonamide, further DT50 and DT90 values of disappearance and mineralisation of p-toluenesulfonamide were estimated using Jandel TablecurveTM 2D (version 4) software.

Mineralisation (sandy loam soil)

Mineralisation was most accurately described by a zero order function. Based upon this function, the calculated DT50 and DT90 values were 102 days and 183 days, respectively.

 

Loss of parent compound (sandy loam soil)

Loss of parent compound (actually p-toluenesulfonamide) was most accurately described by a first order function. Based upon this function, the calculated DT50 and DTgo values for the disappearance of p-toluenesulfonamide were 30 days and 110 days, respectively.

 

Loss of parent compound (humic sand soil)

Loss of parent compound (actually p-tofuenesulfonamide) was most accurately described by a first order function. Based upon this function, the calculated DT50 and DT90 values for the disappearance of p-toIuenesulfonamide were 68 days and 249 days, respectively.

 

Loss of parent compound (low humic content sand soil)

No reasonable fit was found. The DT50 and DT90 values for the disappearance of p-toluenesulfonamide were estimated to be between 28 days and 56 days.

Description of key information

 

Guideline / Test method	Test type	Test para­meter	Test substance concentr.	Half-lives^1
					DT50	DT90
(CTB) (1993) Guidelines for the submission of applications for the registration of pesticides, section H.4.1.Pesticide Bureau, Wageningen, similar to OECD 307	Sandy loam soil, humic sand soil, low humic content sand soil	CO2evolution, (methanol) extractable radioactivity in the solids, bound residues and distribution of radioactivity between parent compounds and metabolite	2.8 mg/kg Chloramine T-trihydrate	Mineralization sandy loam soil^2 Loss of parent compound sandy loam soil^3 Loss of parent compound humic sand soil^3 Loss of parent compound low humic content sand soil^4	102   30   68   28	183   110   249   56

¹ Since [14C]Chloramine-T trihydrate is very rapidly(<< 1 day DT₅₀and DT₉₀)converted to p-toluenesulfonamide DT₅₀and DT₉₀were estimated for p-toluenesulfonamide.

² best described by zero order function

³ best described by first order function

⁴ no reasonable fit, estimated values

Additional information

Tosylchloramide sodium, trihydrate is a strong oxidizing agent in aqueous solution and when brought into contact with organic matter (soil) it reacts and leaves p-tolunenesulfonamide as the only detectable transformation product. The rate and route of p-toluenesulfonamide biodegradation depends on the soil type. But in each tested soil type p-toluenesulfonamide is totally mineralised.