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Short-term toxicity to fish

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Description of key information

The following key information is available for the short-term acute toxicity to fish endpoint:
- Steger-Hartmann T. & Wendt B. (1998) Acute toxicity of di-n-butyltin oxide (ZK 26385) to the Zebra fish Danio rerio. Testing laboratory: Schering AG, Experimentelle Toxikologie. Report no.: IC19. Owner company: Schering AG Report date: 1998-12-11.
- Steger-Hartmann. T & Wendt. B (1998) Acute toxicity of di-n-butyltin bis(2-ethylhexylthioglycolate) (ZK 26386) to the Zebra fish Danio rerio. Testing Laboratory: Schering AG, Experimentelle Toxikologie, D-13342 Berlin. Owner company: Witco GmbH, Bergkamen, Germany. Report No.: IC20. Report date: 1998-11-19.
Further supporting studies are available:
- Nagase et al, 1991
- Grade, 1993 (x2)

Key value for chemical safety assessment

Additional information

Read-across from dibutyltin oxide to diisotridecyl 3,3'-[(dibutylstannylene)bis(thio)]dipropionate concerning aquatic toxicity endpoints was considered appropriate as dibutyltin and octyltins are known to hydrolyse rapidly in water (as presented by Yoder 2003, under the data requirement hydrolysis), and form, in the case of dibutyltins, dibutyltin oxide.

Read across from DBT-2EHMA (CAS: 10584-98-2) has also been used for this endpoint as this is considered the most structurally similar organotin substance with regards to diisotridecyl 3,3'-[(dibutylstannylene)bis(thio)]dipropionate.

Due to the similarity between these test substances and registration substance, it is considered justified to read across to this study.

Both the key studies used to address this endpoint did not conclude LC50 values due to limited mortality seen at the limits of solubility.

- In The Steger-Hartmann T. & Wendt B, 1998 study, an LOEC of 3.1 mg/L was determined.

The study was performed in compliance with GLP and according to the guideline OECD 203. As such, the study was assigned a reliability score of 1 and considered adequate for assessment. Ten Zebra fish were used in each test solution of di-n-butyltin oxide. No mortality was observed in the control. One fish was found dead after 72 hours of exposure in the saturated solution of di-n-butyltin oxide. During exposure, the fish showed signs of abnormal behaviour nearly at all time points. 10% mortality was observed, therefore di-n-butyltin oxide is of low acute toxicity to fish up to 3.10 mg/l (maximum of solubility, determined on the basis of TOC analysis).

This study is being used as read across from Dibutyltin oxide; CAS No. 818-08-6.

- In The Steger-Hartmann T. & Wendt B, 1998 study, an LC50 of > 11.4 mg/L was determined.

The study was a limit test with a mean measured concentration of 11.4 mg/L. This was a saturated solution, prepared as an emulsion and filtered. The test animals were exposed to this environment for a total exposure time of 96 hours, during which time the solution was aerated once (after the 48 hour observation). Aeration of the test solution is allowed according to OECD guideline 203, provided that it does not lead to significant loss of the test material from the solution. As the test material is an organotin complex it is highly unlikely that aeration of the test medium lead to loss of the test material. No deaths occurred at this concentration which was at or above the water solubility limit of the test material. The study was conducted to GLP and OECD guideline 203 and had a high purity of 99.7%, but the deviations in the preparation of the test solution reduce the reliability of the study to 2 on the Klimisch et al, 1997 scale.

This study is being used as read across from dibutyltin bis(2-EHMA); CAS: 10584-98-2.

The following supporting studies are also available:

- The supporting studies, Grade (1993) were both also assigned Klimisch ratings of 2 based on the quality of the method, reporting and accuracy of the results, but as they were based on mixtures rather than pure substances, they were not suitable to be key studies. The lowest LC50 value from a supporting study was determined as 11.7 mg/L with 95 % confidence limits of 7.2 - 19.0 mg/L. This is contradictory to the key studies where no LC50 could be determined. The presence of Mono-n-butyltin tris (2-ethylhexylthioglycolate) at 35% could account for this difference.

These studies are being used as read across from dibutyltin bis(2-EHMA); CAS: 10584-98-2.

- Nagase et al (1991) was provided as supporting information. The study was performed to the guideline OECD 203 in order to examine parameters for a QSAR of 29 organotins, however, areas of the methodology were lacking in detail and therefore it was not possible to accurately assign a reliability score. The LC50 for di-n-butyltin oxide was 0.839 mg/L, determined with red killifish Oryzias latipes. This paper studied the QSAR of 29 organotin compounds. It was concluded that the physicochemical and topological parameters used as independent variables were not good descriptors for estimating the LC50 value.

This study is being used as read across from Dibutyltin oxide; CAS No. 818-08-6.

Key value for chemical safety assessment:

96 hour LC50 (fish): >11.4mg/l (Steger-Hartmann. T, Wendt. B 1998/DBT-2EHMA)