Phosphorodithioic acid, O,O-bis(2-methylpropyl) ester, compd. with N,N-dimethylmethanamine (1:1)

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

5 September - 6 October 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Also in accordance with GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

O,O-bis(2-methylpropyl) sulfanidylphosphonothioate; trimethylazanium

EC Number:

700-910-4

Cas Number:

1354201-99-2

Molecular formula:

C11H28NO2PS2

IUPAC Name:

O,O-bis(2-methylpropyl) sulfanidylphosphonothioate; trimethylazanium

Test material form:

solid

Remarks:

pale yellow glassy solid

Specific details on test material used for the study:

- Name of test material (as cited in study report): S-10713
- Substance type: Straw color, lump solid
- Physical state: solid
- Lot/batch No.: AQ11216TZ
- Expiration date of the lot/batch: July 2013
- Stability: Stable under normal conditions
- Storage condition of test material: Room temperature; in the dark

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum: Domestic activated sludge (mixed microbial population) was collected from the Guelph Wastewater Treatment Plant, Guelph, Ontario on 2012-09-05.

- Preparation of inoculum for exposure:
The sludge was gently aerated and then settled prior to the supernatant being poured off and added to mineral media. This procedure was repeated twice. After the third time, the supernatant was poured off and two mL of stirred concentrated sludge was dispensed onto pre-weighed aluminum weigh boats. Weigh boats were oven-dried for dry weight determination of the sludge inoculum.

- Concentration of sludge: 13 mg/L as total suspended solids

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

15 mg/L

Based on:

other: TOC

Initial test substance concentration 2

Initial conc.:

33.93 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Millipore MilliQ™ reagent water with nutrients (OECD,1992)
- Test temperature: 22 ± 2°C (monitored daily)
- Aeration of dilution water: Approximately 50 mL/min (acceptable range of aeration is 50-100 mL/min)
- Suspended solids concentration: 13 mg/L as total suspended solids
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Glass jars (4000 ml)
- Number of culture flasks/concentration:
3 replicates for the test suspension
2 replicates for the inoculum blank
3 replicates for the reference substance (procedural control)
1 replicate for the toxicity control
1 replicate for monitoring temperature
- Details of trap for CO2:
The CO2 produced in the test system is collected in a series of vessels containing barium hydroxide (Ba(OH)2 • 8 H2O)

SAMPLING
- Sampling frequency: On Days 0, 1, 3, 6, 9, 12, 14, 19, 23, and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Toxicity control: Yes

STATISTICAL METHODS:
The amount of CO2 evolved for any solution was determined by the following equation. The CO2 evolved for any test or reference solution was corrected using the inoculum blank information (i.e., corrected CO2 test = CO2 test – CO2 blank), as outlined in Equation 1.

(1) CO2 produced (mg) = 1.1 (mL barium hydroxide – mL hydrochloric acid titrated)
Calculations of percent biodegradation for test item and reference substance were performed according to Equation 2.
(2) Dt (%) = C(O2 produced (mg)/mg TOC added in test x 3.67) x 100%
Where; Dt = Percent Degradation at time = t

Reference substance

Reference substance:

other: Sodium acetate trihydrate

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

26.9

Sampling time:

28 d

Remarks on result:

other: Average of three replicates.

Details on results:

The toxicity control test obtained 30.0% degradation in 14 days and 28.7% degradation in 28 days. Therefore, toxicity of S-10713 to the microbial population was not observed in this OECD 301B test.
The reference substance achieved 61.2 % biodegradation in 14 days, thus satisfying the acceptability criterion of ≥60% biodegradation in 14 days.
The difference of extreme replicates values of biodegradation at the end of the test was 13.8%, thus satisfying the acceptability criterion of <20% absolute value.
Total CO2 evolution in the inoculated control was 22.9 mg of CO2/L and therefore did not exceed 70 mg/L, thereby meeting the test validity criterion.

BOD5 / COD results

Results with reference substance:

- Biodegradation sodium acetate trihydrate: 61.2% by day 14 and 73.5% by day 28

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Based on data calculations the test material achieved approximately 26.9% biodegradation within the 28 day test. S-10713 is not readily biodegradable (i.e., did not achieve ≥ 60% degradation in 28 days) (OECD, 1992).

Executive summary:

The 'ready' biodegradability of the test material was assessed using the CO2 Evolution Test according to OECD guideline No. 301B and GLP principles.

A single test concentration of ~15 mg/L (as TOC) was tested during 28 days. At the end of the experimental period only 26.9% of the test substance was degraded. Therefore, it is considered as not readily biodegradable.

The present toxicity study is classified as reliable without restrictions since all acceptability criteria stated in the OECD Guideline No. 301 B were met.