Dihydro-2,2-dioctyl-6H-1,3,2-oxathiastannin-6-one

Toxicity to aquatic algae and cyanobacteria

Description of key information

In  an OECD 201 and EU Method C.3 study, Dioctyltin mercaptopropionate induced no effect on the growth of Pseudokirchneriella subcapitata up to and including the highest attainable test concentration of 0.0092 mg/L (geometric mean measured test concentration at nominal concentration 0.025 mg/L). Thus, EC50, EC20 and EC10 were not reached respectively are higher than the water solubility of the substance under the conditions of the test. The No Observed Effect Concentration (NOEC) was the highest technically attainable concentration of nominal 0.025 mg/L (measured 0.0092 mg/L).

Additional information

The effect of Dioctyltin mercaptopropionate on the growth of the green alga Pseudokirchneriella subcapitata was investigated in accordance with the standardised guidelines OECD 201 and EU Method C.3 under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Following a preliminary range-finding test and initial experiment, Pseudokirchneriella subcapitata was exposed to an aqueous solution of the test material at a nominal concentration of 0.025 mg/L (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

The concentration of tin in the test preparations was determined at 0 and 72 hours and the equivalent test material concentrations calculated based on a test material tin content of 15.3 %. Analysis of the 0.025 mg/L test preparation at 0 hours showed a measured tin concentration of 0.0011 mg/L was obtained; equivalent to a test material concentration of 0.0070 mg/L. Analysis at 72 hours showed a measured tin test concentration of 0.0018 mg/L was obtained; equivalent to a test material concentration of 0.012 mg/L. Given the slight variability between the two measured concentrations it was considered appropriate to calculate the result based on the geometric mean measured concentration which was determined to be 0.0092 mg/L as test material.

Exposure of Pseudokirchneriella subcapitata to the test material gave EC50, EC20 and EC10 values based on the geometric mean measured test concentration of greater than 0.0092 mg/L. The No Observed Effect Concentration (NOEC) was the highest tested concentration of 0.0092 mg/L (nominal concentration 0.025 mg/L). This study shows that Dioctyltin mercaptopropionate has no acute or chronic effects on the growth of Pseudokirchneriella supcapitata up to and including the highest attainable test concentration.