The disposable injection syringe can be made of plastic or all-glass syringe, and usually has a scale indicating the volume of liquid in the syringe. Glass syringes can be sterilized with an autoclave, but because the processing cost of plastic syringes is low, most modern medical syringes are made of plastic, which further reduces the risk of blood-borne diseases. The spread of diseases among intravenous drug users, especially the spread of HIV and hepatitis, is related to the repeated use of needles and syringes.