Quaternary ammonium compounds, di-C8-10-alkyldimethyl, chlorides

Endpoint summary

Description of key information

A study was carried out according to EPA OTS 796.3100 (Aerobic Aquatic Biodegradation) using Didecyldimethylammonium chloride (DDAC).

DDAC was evaluated for biodegradability in an aerobic aquatic shake flask test system by exposing DDAC to a mixed microbial inoculum for 28 days. Prior to the 28 day testing period, the mixed microbial inoculum was acclimated to DDAC for 14 days in a defined inorganic salts medium. A loam soil, activated sewage sludge, and influent raw sewage served as sources of the mixed microbial inoculum. Three flasks containing DDAC were utilized in this study. Two flasks containing a reference substance, dextrose, were utilized in order to monitor the viability of the microbial population. Three control flasks containing the microbial inoculum without test or reference substance were utilized in order to determine the endogenous microbial respiration. A sterile test control flask was utilized in order to monitor background CO2, The concentration of carbon from DDAC or dextrose was 10 mg/L. DDAC or dextrose provided the sole source of carbon for the respective systems. All test systems were analyzed for CO2 evolution on days 3, 7, 14, 21, and 28 and for dissolved organic carbon (DOC) on days 0, 3, 7, 14, 21, and 28. The biodegradability of DDAC and dextrose was calculated as percent theoretical CO2 (% ThCO2) evolution which was corrected for endogenous microbial activity for each sample time point. The percent theoretical DOC (%ThDOC) removal of DDAC and dextrose was calculated as % ThDOC removal which was corrected for endogenous values obtained on day 28. For DDAC on day 28, the mean %ThCO2 and the mean %ThDOC removal values were 80.92 % and 84.46 %, respectively. For dextrose on day 28, the mean %ThC02 and the mean %TDOC values were 80.92 and 85.28 %, respectively. These results indicate that the microbial inoculum was viable and that DDAC was ultimately biodegradable under the test conditions.

 

The experimentally determined Log P_OWfor DDAC of 2.59 at 20^oC suggests the test substance has a very low potential for bioaccumulation in the aquatic environment and no additional testing is required. In addition, the test substance may be considered readily biodegradable which may lead to relatively low concentrations of the test substance in the aquatic environment and thus to low concentrations in aquatic organisms. Furthermore, readily biodegradable substance are likely to be rapidly metabolised in aquatic organisms.