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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Description of key information

The following studies have been submitted to address the short-term toxicity to aquatic invertebrates endpoint:
Steger-Hartmann T and Wendt B (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.
The study has been allocated a Klimisch score of 2 and is the key study for this endpoint. The data presented is on the substance dibutyltin oxide.
Steger-Hartmann. T & Schmidt. M (1998) Acute immobilization test of di-n-butyltin bis(2-ethylhexylthioglycolate) (ZK 26386) with Daphnia magna. Testing laboratory: Schering AG, Experimentelle Toxikologie, D-13342 Berlin. Owner company: Witco GmbH, Bergkamen, Germany. Report No.: IC15. Report date: 1998-12-04.
The study was performed in compliance with GLP and OECD Guideline 202. The study was a limit test with a mean measured concentration of 1.4 mg/L. An LC50 value could not be determined from the results of the study.
A further study was provided as supporting information. The study was performed in compliance with GLP and to the guideline EU Method C.2. The test material on which the study was performed contained 65% of the substance of interest.
Grade R (1993) Report on the Acute Toxicity Test of Orgastab 22 M on Daphnia (Daphnia magna Straus 1820). Testing Laboratory: CIBA-GEIGY Ltd, Product Safety Ecotoxicology CH-4002 Basel / Switzerland. Owner company: CIBA-GEIGY Ltd AD - Division, CH-4002, Basel / Switzerland. Report No.: 928293. Report date: 1993-04-21

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.

- The Steger-Hartmann T and Wendt B (1998) 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.

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

- The Steger-Hartmann. T & Schmidt. M (1998) study was a limit test with a mean measured concentration of 1.4 mg/L. This was a saturated solution.

Some immobility was observed but as this level was less than the 10 % allowed immobilisation for a control group, it was determined this was not sufficient to class it as a substance related effect. Thestudy was conducted to GLP and OECD guideline 202 and had a high purity of 99.7%, but no definitive EC50 value could be determined due to the limit of solubility having been reached. Because of this the Klimisch rating was assigned as 2. The EC50 value can only be quoted as > 1.4 mg/L.

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

- The supporting study, Grade (1993), was also assigned a Klimisch rating of 2, but as it was based on a mixture rather than a pure substance, it was not suitable to be a key study. The 48 hour EC50 value from a supporting study was determined as 0.035 mg/L with 95 % confidence limits of 0.027 and 0.044 mg/L. It is likely this lower EC50 value is caused by the presence of Mono-n-butyltin tris (2-ethylhexylthioglycolate) at 35 % concentration.

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

Key value for chemical safety assessment: 48 hour EC50 (Daphnia): 2 mg/l