Dibutyltin oxide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

and also EC guideline 92/69/EEC

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

Concentrations: 0.5 mg/l, 1.1 mg/l, 2.1 mg/l, 4.2 mg/l (the test concentrations were a saturated solution and 3 dilultions thereof, selected according to a preceding limit- and range-finding test).

20 Daphnia were used for each test solution and 20 for the dilution water control. These groups were formed by random allocation of blocks, each consisting of 5 Daphnia. Labelled 100 ml test vessels were used and filled with 45 ml of the test solution or tap water (control group) and 5 ml of the dilution water with the introduction of the Daphina. The Daphnia were exposed to the test solutions and the control solution for a period of 48 hours under static conditions and were not fed during the test period. Immobilization and visual abnormalities were recorded at 24 and 48 hours.

Vehicle:

no

Details on test solutions:

For the stock solution, 100 mg di-n-butyltin oxide was suspended in 1000 ml tap water under constant stirring for approximately 24 hours. Thereafter, the suspension was filtered through a glassfibre filter. This solution was used as the highest test concentration. Aliquots of the solution were further diluted 1:2, 1:4 and 1:8 with tap water in order to preare the appropriate test concentrations.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphia magna Straus

- Source: Schering AG, Experimental Toxicology, Berlin, Germany
- Age at study initiation (mean and range, SD): 0 -24 hours

- Feeding during test
- Food type: Not fed during test period

ACCLIMATION
- Acclimation conditions (same as test or not): Normal tap water was used as dilution water, not polluted with harmful concentrations of chlorine, heavy metals, or organochlorine pesticides, based on quarterly measurements.

- Type and amount of food: The animals were fed continuously with a laboratory culture of microalgae, e.g. Chlorella vulgaris

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

No further information required.

Hardness:

263 mg/l

Test temperature:

Range between 20.1 and 20.5 °C at 0 hours
Range between 20.4 and 20.7 °C at 48 hours

pH:

Range between 7.7 to 7.9 at 0 hours
Range between 8.5-8.6 at 48 hours

Dissolved oxygen:

Range between 8.2 and 8.6 mg/l at 0 hours
Range between 8.6 and 8.7 mg/l at 48 hours

Salinity:

No information available.

Nominal and measured concentrations:

Mean value of the saturated solution = 4.18 mg/l
1:2 diluted (extrapolated) = 2.10 mg/l
1:4 diluted (extrapolated) = 1.05 mg/l
1:8 diluted (extrapolated = 0.52 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 100ml test vessels
- No. of organisms per vessel: 5 Daphnia
- No. of vessels per concentration (replicates): Four replicates of each concentrations
- No. of vessels per control (replicates): Four
- No. of vessels per vehicle control (replicates): One vessel without Daphnia for each test and control solution, used to measure pH, temperature and oxygen content

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water
- Total organic carbon: Control vessel at 0 hours = 5.56 mg/l, at 48 hours = 6.44 mg/l; Test vessel at 0 hours = 8.19 mg/l, at 48 hours, 7.04 mg/l
- Alkalinity: Test vessel at 0 hours = 7.7, at 48 hours = 8.6
- Ca/mg ratio: 4:1
- Conductivity: 731 µS/cm

OTHER TEST CONDITIONS
- Photoperiod: 12 hours light/12 hours dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilization and visual abnormalites were recorded at 24 and 48 hours

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

2.7 mg/L

Nominal / measured:

estimated

Conc. based on:

other: Concentration of the saturated solution was calculated on the basis of the molecular formula.

Basis for effect:

mobility

Remarks:

immobilization

Remarks on result:

other: 2.3-3.2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2 mg/L

Nominal / measured:

estimated

Conc. based on:

other: Concentration of the saturated solution was calculated on the basis of the molecular formula

Basis for effect:

mobility

Remarks:

immobilization

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

1.1 mg/L

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.1 mg/L

Details on results:

The highest concentration without immobilization of Daphnia was 1.1 mg/l based on TOC analysis. The EC50 for the compound was calculated by the computer programme ("Probit analysis", version 1), Institute of Biometrics, Berlin, Germany. The calculated EC50 was 2 mg/L.

Reported statistics and error estimates:

No information- confidence limits could not be calcuated due to the steep exposure/effect curve resulting in just one concentration between 0 and 100% effect.

Cumulative immobilization of Daphnia magna after exposure to di-n-butyltin oxide

Dilution of di-n-butyltin oxide	Conc (mg/l)	Total no. of Daphnia	No. of immobilized Daphnia
			24 hours	48 hours
0 (control)	0	20	0	0
1:8	0.5	20	0	0
1:4	1.1	20	0	0
1:2	2.1	20	8	12
Saturated solution	4.2	20	18	20

Validity criteria fulfilled:

not specified

Conclusions:

The EC50 for 48 hours for di-n-butyltin oxide was determined to be 2.0 mg/l based on TOC concentration analysis. The highest concentration no effect was 1.1 mg/l. Additional to the TOC analysis a tin analysis was performed with AAS at Witco laboratories under non-GLP conditions. The measured Sn content of 1.6 mg/l results in a concentration of 3.4 mg ZK 26385/l in the saturated solution. This is in acceptable agreement with the concentration of 4.2 mg/l determined on the basis of TOC analysis.

Executive summary:

20 Juvenile Dapnia magna were exposed to four test concentrations of di-n-butyltin oxide and 20 for the tap water control. The Daphnia were exposed for a period of 48 hours under static conditions. Immobilization was recorded at 24 hours and 48 hours. For the preparation of the test solutions a suspension with a nominal loading of 100 mg/l was stirred for 24 hours. This suspension was filtered through a glass fibre filter. The resulting solution served as the highest concentration (saturated solution). Since in a preceding range-finding test, the EC50/48 h was estimated between the saturated solution and a 1:10 dilution, the saturated solution was diluted 1:2, 1:4, 1:8 for definitive testing. The test temperature was in the range of 20.1 to 20.7 degrees C, the pH ranged between 7.7 and 8.6, and the oxygen concentration between 8.2 and 8.7 mg/l. The light/dark rhythm was adjusted to 12 hours/12 hours. The organic carbon concentration of the highest test solution (saturated) was analyzed with a TOC analyzer at the start of exposure and 48 hours thereafter. The substance concentration was calculated on the basis of the molecular formula. The calculated concentration of the saturated solution was 6.8 mg/l at the beginning of the test and 1.6 mg/l at the end of the exposure period with a mean of 4.2 mg/l. The concentrations of the further dilutions were extrapolated. Statistical evaluation regarding the observations of immobilization was performed by probit analysis. Immobilized Daphnia were observed in the test concentrations containing 2.1 and 4.2 mg/l di-n-butyltin oxide, calculated on the basis of TOC analysis. The EC50 for 48 hours for di-n-butyltin oxide was determined to be 2.0 mg/l based on TOC concentration analysis. The lowest concentration without effect was 1.1 mg/l.

Description of key information

The following study has been submitted to address the short-term toxicity to aquatic invertebrates endpoint:

 

Steger-Hartmann T and Wendt B (1998). Acute toxicity of di-n-butyltin oxide (ZK 26385) to Daphnia magna. Testing laboratory: Schering AG, Experimentelle Toxikologie, D-13342, Berlin Germany. Report no.: IC19. Owner company: Schering AG, Experimentelle Toxikologie, Berlin Germany. Study number: TXST19980196. Report date: 1998-12-11. The 48 hour EC50 was determined as 2 mg/L.

 

The study has been allocated a Klimisch score of 2 and is the key study for this endpoint.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

2 mg/L

Additional information

The key study Steger-Hartmann T and Wendt B (1998) was provided as the key study for this endpoint. The study was performed to the OECD Guideline 202, no statement was provided whether the study was GLP compliant. The study was assigned a reliability score of 2 and considered suitable for assessment. 20 Juvenile Dapnia magna were exposed to four test concentrations of di-n-butyltin oxide and 20 for the tap water control. The Daphnia were exposed for a period of 48 hours under static conditions. Immobilization was recorded at 24 hours and 48 hours. For the preparation of the test solutions a suspension with a nominal loading of 100 mg/l was stirred for 24 hours. This suspension was filtered through a glass fibre filter. The resulting solution served as the highest concentration (saturated solution). The EC50 for 48 hours for di-n-butyltin oxide was determined to be 2.0 mg/l based on TOC concentration analysis. The highest concentration no effect was 1.1 mg/l. Additional to the TOC analysis a tin analysis was performed with AAS at Witco laboratories under non-GLP conditions. The measured Sn content of 1.6 mg/l results in a concentration of 3.4 mg ZK 26385/l in the saturated solution. This is in acceptable agreement with the concentration of 4.2 mg/l determined on the basis of TOC analysis.