4,4-dimethyloxazolidine

Endpoint summary

Description of key information

Short-term EC50 and NOEC values for 4,4-Dimethyl-1,3-oxazolidine (CAS no. 51200-87-4) are available for two trophic levels of the aquatic freshwater compartment (aquatic invertebrates, algae) from GLP studies according to EPA guidelines (aquatic invertebrates) and OECD 201 (algae).  

Growth inhibition study aquatic algae (Selenastrum capricornutum) (OECD 201, 1984): 

ErC50 (72h): 6.57 mg/l nominal concentration 

NOErC (72h): 2.5 mg/l nominal concentration 

Short term toxicity on invertebrates (Daphnia magna) (U.S. EPA, Ecol. Res. Ser. 660/3-75009, 1975): 

LC50 (48h): 45 mg/l estimated concentration (statistical result using a computerized program, moving average test)

Additional information

Algae

Ecotoxicological testing of Bioban CS-1135 (CAS 51200-87-4) was conducted to determine the growth inhibition of the freshwater green alga, Selenastrum capricornutum Printz, according to the OECD Method 201 (Alga, Growth Inhibition Test, 1984) and in general accordance with OPPTS Method 850.5400 (Algal Toxicity, Tiers I and II, 1996).
Results from the range-finding test indicated that the 50% inhibitory effect level and the no effect level for growth inhibition of Selenastrum capricornutum were between 1 and 10 mg/L for all endpoint parameters (72 and 96 -hour cell number, area under growth curve and growth rate).
The available analytical methods for the test item were not able to extract and quantify this compound. Calculations of all statistical endpoints for the definitive test were conducted using nominal concentrations. The 72 and 96 -hour EC50s for cell number were 3.79 and 5.42 mg/L, respectively. The 72 and 96 -hour EC50s for area under the growth curve were 3.76 and 4.20 mg/L, respectively. The 0 to 72 and 0 to 96 -hour EC50s for growth rate were 6.57 and 7.14 mg/L, respectively. The NOEC and LOEC for 72 -hour cell number and area under the growth curve were 1.25 and 2.50 mg/L, respectively. For the other four endpoint parameters, the NOEC and LOEC were 2.50 and 5.00 mg/L, respectively. 

Daphnia

Key study
The acute toxicity of the test material to Daphnia magna was assessed using the methods outlined by the Commitee on Methods for Toxicity Tests with Aquatic Organisms (US methods). Water quality parameters of temperature, dissolved oxygen and pH were measured at the termination of the test and were within acceptable limits. The estimated LC50 at 24 hr was 75 (56-100) mg/L and at 48 hr was 45 (32-56) mg/L (95 percent confidence limits in parenthesis). The 48 hr "no effect" level was 32 mg/L. 

Supporting study
Further, there is one non-GLP supporting study available for aquatic invertebrates according to EPA guidelines:
Short term toxicity on invertebrates (Daphnia magna) (U.S. EPA suggested guidelines, CFR Vol. 43, Part 163.72-2)
LC50 (48h): 51 mg/l measured concentration (analytical method not specified)

Conclusion on classification 

The environmental classification of 4,4-Dimethyl-1,3-oxazolidine (CAS no. 51200-87-4) is currently not harmonised according to the CLP Regulation (EC) 1272/2008. Based on available acute aquatic toxicity data, the lowest valid effect concentration for freshwater aquatic organisms is 6.57 mg/L (ErC50 for algae). Based on the available acute data, the substance should not be classified for acute toxicity following Annex I, table 4.1.0a of the CLP regulation (there are no acute values <=1 mg/L).