Tetrabutyltin

Endpoint summary

Description of key information

Short term toxicity to fish

Tetrabutyltin was determined to have a 96 hour LC50 value of 45.2 µg/L, along with an 96 hour EC50 value also of 45.2 µg/L.

Short term toxicity to aquatic invertebrates

Tetrabutyltin was determined to have a 48 hour EC50 of 1.3 mg/L with respect to daphnia magna.

Long-term toxicity to aquatic invertebrates

21 day NOEC Daphnia magna = 14 µg/L (based on reproductive output, mortality of parentals, body length)

21 day LC50 Daphnia magna = 51 µg/L (based on mortality of parental daphnids)

Toxicity to aquatic algae and cyanobacteria

The 72 hour EC50 of Tetrabutyltin was 17 µg/L when tested with S. costatum for growth rate.

Toxicity to microorganisms

A dose related response was not seen with values of repeats differing significantly. Therefore no EC50 value could be determined for this study. The lack of definitive result is likely to be due to the poor solubility of the test substance.

Additional information

Short term toxicity to fish

Four studies are available to address this endpoint.

Short-term toxicity to fish.001: 96 hr LC50: 45.2 ug/L, 96 hr EC50: 45.2 ug/L

Short-term toxicity to fish.002: LC50: 9 µg/L

Short-term toxicity to fish.003: 96 hr LC50: 185 µg/L

Short-term toxicity to fish.004: 48 hr LC50: 5.21 mg/L

Short-term toxicity to fish.001 was selected as the key study on the basis that it was conducted for 96 hours and the methodology was well documented. The LC50 value obtained in the study was 45.2 µg/L, which was significantly lower than the other 96 hour study.

Short term toxicity to aquatic invertebrates

Four studies are available to address this endpoint.

Short-term toxicity to aquatic invertebrates.001: Daphnia magna: EC50 (48 h): 1.3 mg/L (95% confidence limits 1.2 -1.4 mg/L), 48 h NOEC 0.56 mg/L

Short-term toxicity to aquatic invertebrates.002: The 24 hr EC50 (immobilization) for daphnia exposure to tetrabutyltin was 1.55 mg/L

Short-term toxicity to aquatic invertebrates.003: Daphnia magna: EC50 2.0 µg/L

Short-term toxicity to aquatic invertebrates.004: The LC50s for Cladocera and Anostraca exposure to tetrabutyltin are 776 and 53 µg/L, respectively

Short-term toxicity to aquatic invertebrates.001was determined as the key study for this endpoint as it was conducted to an OECD guideline, complied with GLP and was assigned a reliability rating of 2, according to the criteria of Klimisch et al. (1997). This was considered the most reliable study as all supporting studies have a reliability rating of 4, according to the criteria of Klimisch et al. (1997).

Long-term toxicity to aquatic invertebrates

One study is available. In a 21 day study of daphnia magna, the following time weighted average concentration results were obtained:

21 day NOEC = 14 µg/L based on reproductive output, mortality of parentals, body length

21 day LC50 = 51 µg/L mortality of parental daphnids

Toxicity to aquatic algae and cyanobacteria

Once study is available. The EC50 of tetrabutyltin was 17 µg/L when tested with S. costatum for growth rate. The EC50 and LC50 for tetrabutyltin on cell death of S. costatum are 186 and >500 µg/L, respectively.

The EC50 values reported for tests on cell death are greater than those of growth tests because biomass at the time of exposure was greater. Extensive death of cells at or near the EC50 concentration may indicate greater hazard than when the LC50 far exceeds the EC50, These data show that populations of algae exposed to relatively high concentrations of organotins (up to 50 µg/L) over a short period of time may recover without input of new cells. However, the data do not show whether recovery was due to adaptation of surviving cells or loss of toxicant from the medium by volatilization, adsorption to dead cells or to walls of exposure vessels, degradation or a combination of these factors.

Toxicity to microorganisms

Four studies are available to address this endpoint

Toxicity to microorganisms.001: 30 minute exposure; results indicate a slight inhibitory effect on the activity of microorganisms from a municipal sewage treatment plant at the maximum solubility of the test compound

Toxicity to microorganisms.002: 18 hour EC50 = 1.7 mg/L

Toxicity to microorganisms.003: 30 minute EC50 = 1.1 µg/L

Toxicity to microorganisms.004:The EC50 (at 15 minutes) was 1.6 µmol/L in Vibrio fischeri 

Toxicity to microorganisms.001 was conducted in accordance with GLP following OECD 209. It was therefore selected as the key study. A dose related response was not seen with values of repeats differing significantly. Therefore no EC50 value could be determined for this study.

Values from the supporting studies are wildly different from the key study and from each other. The variability of the results is likely to be due to the poor solubility of the test compound. The use of a vehicle is likely to aid solubility and this may help to explain why the supporting studies saw a dose related inhibitory effect unlike the key study.