This publication applies to medical devices that come into direct or indirect contact with the human body and are subject to Premarket Application (PMA) and Premarket Notification (510(k)) requests in order to determine potential toxicity. This publication may be used for evaluation of other medical devices. This publication addresses high and low pressure gas systems. It applies to both metallic and nonmetallic materials including lubricants, ceramics, and glass that contact the caregiver or the patient using the medical device. Contact can include direct contact with the material or contamination of the gas stream with potentially toxic materials. The gas stream can be contaminated through contact with a wetted component or through a reaction of the gas with an internal component of the medical device. See CGA G-4.10, Use of Nonmetallic Materials in High Pressure Oxygen Breathing Gas Applications for use of nonmetallic materials in oxygen as it relates to ignition.