Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Both effect and exposure assessment should be performed on an equal basis for all QAS substances and so read-aross from C12-C16 ADBAC was applied to assess the terrestrial toxicity of C16 -18 TMAC. It was considered unreasonable to use a high organic matter content (sorption) in exposure assessment where on the effect side an extreme low (< 0.2%) organic matter content (sorption) is used. The most sensitive species tested in sand wasT. pratense, with an EC50(growth) of 19 mg/kg ww. The sand used, consisted of  >99.8% SiO2and a particle size 150-210 µm. With loam soil (48.2% sand, 42.8% silt and 9% clay, 1.41% OC) alsoT. pretensewas the most sensitive species but with an EC50(growth) of 309 mg/kg ww. In the current assessment the PEC is calculated using an average Koc of 282624.3 L/kg based on soils with an average organic carbon content of 4.3% where on the effect side a test result is used with an organic carbon is used of <0.2%. This is considered extremely unrealistic. It was therefore justified to use the EC50(growth) of 537 mg/kg dw which was tested on a soil with 1.41% organic carbon as a realistic worst-case lowest endpoint for the toxicity of C16 -18 TMAC TMAC derived from the terrestrial studies conducted with C12 -C16 ADBAC.