Residual formaldehyde on plastic materials and medical equipment following low-temperature steam and formaldehyde sterilization

We measured the amount of residual formaldehyde on 16 plastic materials and five medical devices following low-temperature steam and formaldehyde (LTSF) sterilization, based on the European Standard EN14180. The amounts of formaldehyde residue on the plastic materials were compared with that on a filter paper of similar dimensions. The amount of residual formaldehyde on polyamide 6, polyurethane, natural rubber and polyacetal was higher (21.9, 15.2, 3.0 and 2.1 times, respectively) than that on the filter paper. The amount of formaldehyde recovered from a breathing circuit, anaesthesia circuit, oxygen tubing, airway tube and tweezers was 260, 240, 594, 56 and 0 microg, respectively, following LTSF sterilization. Our results emphasize the need to verify the main material composing the medical equipment before LTSF sterilization, as the amount of formaldehyde retrieved following sterilization varies according to the material used for construction.