Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

The 96-hour LC50 value of >116 mg/L for tin bis(2-ethylhexanoate) was taken from a valid exposure study with rainbow trout (Oncorhynchus mykiss). In an acute, static, toxicity study with Daphnia magna,the 48-hour EC50 value for tin bis (2-ethylhexanoate) was > 100 mg/L based on nominal concentrations. The 72-hour NOEC and ErC50 for Pseudokirchneriella subcapitata exposed to tin bis(2-ethylhexanoate) was 0.54 and 6.9 mg/L, respectively. The acute toxicity value of 6.9 mg/L was the lowest acute value among the three trophic levels of examined aquatic organisms. Thus, this value was used in the derivation of the PNECaqua.

Additional information

One acute freshwater fish study with rainbow trout (Oncorhynchus mykiss) was assessed for this endpoint. This study was determined to be acceptable for use in risk assessment (Klimisch score = 2). Rainbow trout were exposed to a geometric series of five test concentrations and a negative (dilution water) control for 96 hours in a static-renewal exposure system. Test solutions were renewed every 24 hours. Observations of mortality and other signs of toxicity were made approximately 3.5, 24, 48, 72 and 96 hours after test initiation. The 24, 48, 72, and 96 hour LC50 values were >116 mg/L tin bis(2-ethylhexanoate).

One static acute toxicity test with Daphnia magnaconducted according to OECD 202 under GLPwas available for tin bis (2-ethylhexanoate). This study was determined to be acceptable for use in risk assessment (Klimisch score = 1). The study was conducted as a limit test, with four replicate vessels of five daphnids per test level, exposed to nominal test concentrations of 0 (water control) and 100 mg/L tin bis (2-ethylhexanoate). Measured concentrations of the exposures ranged from 95.9 to 97.4% of the nominal concentration over the course of the exposure period. Observations were made at 24 and 48 hours for daphnid immobility and any changes in behavior or appearance. The 48-hour EC50 value was reported as > 100 mg/L based on nominal concentrations. The 48-hour NOEC value was reported as 100 mg/L based on nominal concentrations.

 

In a valid toxicity study with Pseudokirchneriella subcapitata (Klimisch score = 2), algal cells were exposed to nominal test concentrations of 0, 0.25, 0.55, 1.2, 2.7 and 6.0 mg/L tin bis(2-ethylhexanoate). Measured test concentrations were determined from samples of test medium collected from each treatment and control group at the beginning and end of the test. Samples were collected from each replicate test chamber at approximately 24-hour intervals during the test to determine cell densities. Areas under the growth curve and growth rates were used to calculate percent inhibition values relative to the control over the 72 -hour exposure period. The 72-hour NOEC and EC50 based on growth rate were 0.54 and 6.9 mg/L, respectively. The 72-hour NOEC and EC50 based on biomass were 0.22 and 1.0 mg/L, respectively. Since the use of the average specific growth rate for estimating toxicity is scientifically preferred (OECD 201), this toxicity value was selected as key for this endpoint.

 

The acute toxicity value of 6.9 mg/L was the lowest acute value among the three trophic levels of examined aquatic organisms. Thus, this value was used in the derivation of the PNECaqua.