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Short-term toxicity to aquatic invertebrates

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Link to relevant study record(s)

Description of key information

The following studies have been submitted:
Hooftman R. N. and De Wolf J. M. (2003). 1,3,2-Dioxastannepin-4,7-dione, 2,2-dibutyl-(dibutyltin maleate, CAS # 78-04-6): Static acute toxicity test with the crustacean species Daphnia magna. Testing laboratory: TNO, Project Organisation, Ecotoxicology, Utrechtseweg 48, P. O. Box 360, 3700 AJ Zeist, The Netherlands. Report no.: V4017/04. Owner company: Organotin Environmental Programme (ORTEP) Association, Stabilizer Task Force. Report date: 2003-09-15.
In this static acute toxicity test with the crustacean species Daphnia magna, the 48h EC50 for the test material was calculated to be 0.21 mg/L (2.7 vol. % of the saturated solution) and the observed 48h NOEC was 0.079 mg/L (1.0 vol% of the saturated solution), based on the mobility and condition of the test and the condition of the test animals.
Steger-Hartmann, T. & Schmidt, M. (1998). Acute immobilization test of di-n-butyltin oxide (ZK 26385) with Daphnia magna. Testing laboratory: Schering AG, Experimentelle Toxikologie, D-13342 Berlin, Germany. Report no.: IC26. Owner company: Schering AG, Experimentelle Toxikologie, Berlin, Germany. Study number: TXST19980203. Report date: 1998-12-03.
Result: The EC50 for 48 hours for di-n-butyltin oxide was determined to be 2.0 mg/L based on Total organic Carbon (TOC) concentration analysis. The highest concentration with no effect was 1.1 mg/l.
Hooftman and De Wolf (2003) has been performed using dibutyltin maleate (CAS: 78-04-6) and is being used for read-across purposes to fulfil the endpoint for dibutyltin methyl maleate (CAS: 15546-11-9). Dibutyltin maleate is determined to be the structure most similar to dibutyltin methyl maleate and so this study is considered the key study for this endpoint.
The supporting study, Steger-Hartmann and Schmidt (1998) was performed on dibutyltin oxide. The study was performed to the guideline and to GLP but is allocated a Klimisch score of 2 as it was performed on a read-across substance.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.21 mg/L

Additional information

The key study Hooftman R. N. and De Wolf J. M. (2003) was performed to the OECD guideline 202 and in compliance with GLP, the study was considered reliable and adequate for assessment, however as the study was performed on a read-across substance, the study was assigned a reliability score of 2. In a static acute toxicity test with the crustacean species Daphnia magna study, the 48h EC50 for the test material was calculated to be 0.21 mg.l-1(2.7 vol. % of the saturated solution) and the observed 48h No Observable Effect Concentration (NOEC) was 0.079 mg.l-1(1.0 vol% of the saturated solution), based on the mobility and condition of the test animals, respectively. Partial immobility was observed at 3.2 vol. % and the higher dilutions tested. At 1.0 vol. %, one animal was immobile, however according to the OECD guideline 10% immobility is allowed and therefore this immobility is not taken into account to estimate the NOEC value for mobility. In addition effects with respect to condition were limited to one single slow swimming animal at 10 vol. %. These data support the conclusion that the NOEC for both the mobility and condition endpoints is 1.0 vol. %. There were no immobile animals in the control medium at the end of the test.

 

The supporting study Steger-Hartmann, T. & Schmidt, M. (1998) was performed to the OECD guideline 202. The study was assigned a reliability score of 2. Twenty juvenile Daphnia 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 glassfibre 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 Total Organic Carbon (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 highest concentration without effect was 1.1 mg/l.

Study Hooftman and De Wolf (2003) has been performed using dibutyltin maelate (CAS: 78-04-6) and is being used for read-across purposes to fulfil the endpoint for dibutyltin methyl maleate (CAS: 15546-11-9). Dibutyltin maleate is determined to be the the structure most similar to dibutyltin methyl maleate and so this study is considered the key study for this endpoint.

The study has been performed to the appropriate guideline and to GLP, however as the study is being used for read-across purposes the Klimisch score has been reduced from a 1 to a 2.

Study Steger-Hartmann and Schmidt (1998) has been performed using dibutyltin oxide and so is used a supporting information due to the fact that it is known that organotin ligands are expected to hydrolyse to this form over time.

The study has been performed to the appropriate guideline but is allocated a Klimisch score of 2 as the reliability is reduced for read-across purposes.

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