Is IDbCommandInterceptor in EntityFramework 6 thread safe

Is a IDbCommandInterceptor instance considered thread-safe when registered with the DbInterception add method? I have implemented a class that conforms to the IDbCommandInterceptor interface and am tracking the start time of a command when one of the executing methods are invoked compared to the stop time when the corresponding executed method is called. I'm storing this information in a private ivar list and need to know if what I'm doing is safe.