an intermediate member between them either by welding gluing snap lock fit screws or other attachment mechanisms known in the art the attachment is designed to be semi permanent in that the user does not normally remove the physical parts that are said to be attached u201c associated with u201d means that the devices in question are permanently or detachably coupled associated with is intended to be broader in scope than u201c attached to u201d and covers devices that users may or may not be able to remove in accordance with this invention it has been found that a syringe may be provided for normal operation which permits changing a needle subsequent to use but which upon completion of normal operation and continued movement of a plunger results in a triggering of a needle hub with the interchangeable needle to project such needle harmlessly into the plunger and body of the syringe once trapped inside the plunger and body of the syringe the needle is no longer subject to accidental pricking or poking of human tissue thus minimizing the likelihood of transfer of a contagious disease which may be carried by fluids contained on the surface of or within such needle to prevent possible leakage of residual fluids in the needle the syringe is scaled after use and after such use an automatic indication is given that the syringe represents a biohazard various other advantages and features will become apparent from a reading of the following description given with reference to the various figures of drawing fig1 is a cross sectional view illustrating a subassembly of a needle hub 2 base 4 barrel 6 needle assembly 8 and an energy storage means 10 of a syringe 1 shown in fig1 of this invention in.