Dodecyl(2-hydroxy-3-sulphonatopropyl)dimethylammonium

Endpoint summary

Description of key information

The biodegradability of dodecyl(2-hydroxy-3-sulphonatopropyl)dimethylammonium was determined in accordance with the version of OECD TG 301C (MITI-I test) that is the standard method used under Japanese law for the notification of new chemical substances in Japan.  The test substance was applied at 100 mg/L in the presence of a composite inoculum at a concentration of 30 mg suspended solids/L.  Biochemical oxygen demand (BOD) was recorded continuously during the 28-day incubation and was related to the theoretical demand (ThOD) that corresponds to mineralisation of all components to their highest oxidation state, based on a composite empirical formula representing the sum of all components. In addition, measurements of dissolved organic carbon (DOC) were made in all vessels at the end of the test and the media were also analysed by LC-MS to detect residues of constituents initially present and undegraded breakdown products and intermediates.

According to OECD TG 301C, the criterion of ready biodegradability is that the percentage biodegradation by BOD reaches 60% on Day 28. Since the mean measured BOD reached 63% ThOD after 28 days, the test item is considered readily biodegradable.

Additional information

A study of the ready biodegradability of Betadet S-20 was performed according to the closed Bottle Test (OECD TG 301D).  The study was dosed with Betadet S-20 at a concentration of 10 mg/L, based on a chemical oxygen demand (COD) value of 0.43 mg O2/mg determined by a bench-top digestion kit system, and the same COD value was used as the comparator for calculating percentage biodegradation from measurements of biochemical oxygen demand (BOD) recorded at intervals during the 28-day incubation.  However, the COD value obtained for Betadet S-20 is ca. 5x lower than would be anticipated based on structural considerations, which suggests the COD determination achieved only partial oxidation.  This would in turn mean that the biodegradation percentages calculated for Betadet S-20 are over-estimated by a similar margin.  Betadet S-20 was reported to have achieved 78% biodegradation in 28 days and to have fulfilled the criteria for classification as readily biodegradable, however these findings must be considered to be unreliable in view of the uncertainty over the COD value. The test data do provide qualitative evidence of at least partial Betadet S-20 mineralisation under stringent Closed Bottle Test conditions, but they are presented as supporting information only.