Tetrabutyltin

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:

18 March to 15 April 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

not specified

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.6 (Degradation: Chemical Oxygen Demand)

Deviations:

not specified

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

ZK 24.942

IUPAC Name:

ZK 24.942

Constituent 2

Reference substance name:

Tetrabutyltin

EC Number:

215-960-8

EC Name:

Tetrabutyltin

Cas Number:

1461-25-2

Molecular formula:

C16H36Sn

IUPAC Name:

tetrabutylstannane

Test material form:

liquid

Details on test material:

- Name of test material (as cited in study report): ZK 24.942
- Physical state: clear liquid
- Analytical purity: 99.93 %
- Lot/batch No.: W91/14
- Expiration date of the lot/batch: 5 Sept 1993
- Storage condition of test material: Room temperature in darkness

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

A sample of activated sewage sludge was collected from the sewage treatment farm. The sample was allowed to settle for approx 30 minutes and the supernatant was filtered through Whatman GFA coarse filter paper (first 250 mL discarded). The filtrate was maintained under aeration and used within 24 hours of collection.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The standard nutrient medium was composed of the following:
Solution 1:
KH2PO4: 8.5 g/L
K2HPO4: 21.75 g/L
Na2HPO4.2H2O: 33.3 g/L
NH4Cl: 1.7 g/L
Solution 2:
MgSO4.7H2O: 22.5 g/L
Solution 3:
CaCl2: 27.5 g/L
Solution 4:
FeCl3.6H2O: 0.25 g/L

1 mL of each of solutions 1-4 were added to each litre of aerated reverse osmosis purified and deionised water. The nutrient medium was left at room temperature (approximately 20 °C), under gentle agitation.

- Test temperature: 20 °C
- Continuous darkness: yes/no

SAMPLING
- Sampling frequency: Sufficient bottles were prepared in each test and control series to allow a single oxygen determination per bottle to be made at 0, 5, 15, and 28 days (duplicate bottles at each sampling time). Sufficient bottles for series (f) were prepared to provide information on inhibitory effects of days 0 and 28.


CONTROL AND BLANK SYSTEM
- Inoculum blank: Inoculated nutrient medium
- Toxicity control: 2 mg/L test substance plus filter paper and 3 mg/L sodium benzoate

STATISTICAL METHODS:
Theoretical Oxygen Demand (ThOD)
For a compound CcHhClclNnPpSsOoNana the theoretical oxygen demand may be calculated from:
ThOD(NO3) = 16([2c + ½(h-cl] + 5/2n + 5/2p + 3s + 1/2 na – o]/Molecular weight)

So for sodium benzoate. C6H5COONa. Mol. Wt. = 144

ThOD = 16([14 + 2.5 + 0.5 -2]/144) = 1.67 mgO2/mg

Estimated oxygen depletion for 3 mg/L = 5.01 mgO2/L

For ZK 24.942. C16H36Sn. Mol. Wt. = 347

ThOD = 16[32 + 18]/347 = 2.305 mgO2/mg
Estimated oxygen depletion for 2 mg/L = 4.61 mgO2/L

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

28 d

Details on results:

ZK 24.942 attained only 2 % biodegradation within 28 days and therefore cannot be termed readily biodegradable.

BOD5 / COD results

Results with reference substance:

Sodium benzoate attained 86 % biodegradation after 28 days.

Any other information on results incl. tables

Table 1: Dissolved oxygen measurements (mgO2/L)

Culture medium		Day
		0	5	15	28
a) Nutrient medium without inoculum     b) Nutrient medium with inoculum     c) Nutrient medium with inoculum     d) Test substance 2 mg/L plus filter paper     e) standard substance 3mg/L sodium benzoate     f) Test substance (2 mg/L) plus filter paper and sodium benzoate	R1 R2 Mean R1 R2 Mean R1 R2 Mean R1 R2 Mean R1 R2 Mean R1 R2 Mean	8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90 8.90	8.86 8.90 8.88 8.87 8.40 8.64 8.90 8.90 8.90 8.74 8.90 8.82 5.00 4.96 4.98 - - -	8.74 8.78 8.76 8.68 8.60 8.64 8.74 8.65 8.70 8.60 8.66 8.63 5.11 4.43 4.77 - - -	8.62 8.68 8.65 8.47 8.50 8.49 8.58 8.48 8.53 8.35 8.60 8.48 4.30 4.01 4.16 4.08 4.20 4.14

R1 & R2 Replicates 1 and 2

 

Table 2: Mean oxygen depletion and percent biodegradation values

Culture medium		Day
		5	15	28
a) Nutrient medium without inoculum	} O2 depletion (mg O2/L)	0.02	0.14	0.25
b) Nutrient medium with inoculum	} O2 depletion (mg O2/L)	0.26	0.26	0.41
c) Nutrient medium with inoculum	} O2 depletion (mg O2/L)	0	0.20	0.37
d) Test substance 2 mg/L plus filter paper	} O2 depletion (mg O2/L) } % degradation	0.08 2	0.07 2	0.05 1
e) standard substance 3mg/L sodium benzoate	} O2 depletion (mg O2/L) } % degradation	3.66 73	3.87 77	4.33 86
f) Test substance (2 mg/L) plus filter paper and sodium benzoate	} O2depletion (mg O2/L)	-	-	4.39

 

(ii) Test substance

Oxygen depletion = (a – d) – (a – c) from table 1

(ii) Standard substance (sodium benzoate)

Oxygen depletion = (a – e) – (a – b) from table 1

(iii) Inhibition check (test substance plus sodium benzoate)

Oxygen depletion = (a – f) – (a – c) from table 1

(iv) Inoculated and non-inoculated nutrient medium (plus filter paper blank)

Oxygen depletion = initial O₂concentration – measured value

(v) % Degradation = (Oxygen depletion/Conc. of substance x ThOD NO3) x 100

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Interpretation of results:

not readily biodegradable

Conclusions:

ZK 24.942 attained 2 % biodegradation within 28 days and therefore may not be termed as readily biodegradable.

Executive summary:

A study was performed to assess the ready biodegradability of ZK 24.942 in accordance with OECD Guideline for Testing of Chemicals No. 301D and EEC Methods for the Determination of Ecotoxicity, EEC Directive 67/548 Annex V Part C.6 (84/449/EEC), Closed Bottle Test. ZK 24.942 attained 2 % biodegradation within 28 days and therefore may not be termed as readily biodegradable. ZK 24.942 was not found to be inhibitory to activated sewage sludge bacteria under the conditions of this test.