Isooctyl acrylate

Toxicity to microorganisms

Additional information

The toxicity of IOA to microorganisms was tested in three studies. In the key study, a limit test with 3-hours’ exposure, IOA caused less than 50% reduction in respiration of an activated sludge of predominantly domestic sewage when tested at a loading rate of 1000 mg/L. The 3-hour EC50 to activated sludge organisms is therefore >1000 mg/L. The two supporting studies were conducted using the Microtox ® testing system, with Photobacterium phosphoreum as the test organism. This system assesses inhibition of bioluminescence. A total of five runs using three individual stock solutions were done with EC50 values ranging from 0.110 mg/L to 0.330 mg/L. The geometric mean of the average 15-minute EC50 for each stock solution was 0.203 mg/L.   The toxicity exerted is not applicable to sewage treatment plant microorganisms, but 15 minute EC50 values demonstrate that IOA may have the potential for toxicity in marine bacteria.

 

The key study was conducted according to internationally accepted test guidelines and in compliance with GLP criteria. It is classified as reliable without restrictions. The supporting studies were based on a standardized commercial toxicity test kit and were done according to the vendor's directions. However, details of the analytical study are not provided and the study was not conducted according to GLP criteria. In addition, the response of P. phosphoreum is not directly applicable to that of wastewater treatment microorganisms. Therefore, the supporting studies are classified as reliable with restrictions. It is the sponsor’s judgment that the 3-hour exposure to activated sludge results provides the most accurate assessment of IOA toxicity to wastewater treatment organisms.