The U.S. Food and Drug Administration (FDA) reminds laboratory staff to use transport media (the liquid that maintains a specimen sample while it is transported to a laboratory) that are compatible with the SARS-CoV-2 testing platforms and the processes used in their laboratory to process samples collected from people who are being tested for SARS-CoV-2. There is a risk of exposure to harmful cyanide gas, a by-product of a reaction between guanidine thiocyanate or similar chemicals and bleach (sodium hypochlorite), when certain transport media are used with an incompatible testing platform or laboratory process. Guanidine thiocyanate may be referred to as guanidinium rhodanide, guanidinium thiocyanate, or guanidinium.
There are numerous transport media that contain guanidine thiocyanate or similar chemicals. PrimeStore molecular transport media (MTM) (LH-1-02 and LH-1-03), Zymo DNA/RNA Shield, Spectrum Solutions Saliva Collection Device, and any other transport medium containing guanidine thiocyanate or similar chemicals, should not be used in a testing platform such as the Hologic Panther and Panther Fusion Systems that use bleach or in laboratories that use bleach as part of their normal laboratory processes. When the bleach interacts with the guanidine thiocyanate or similar chemicals in the transport media, it produces cyanide gas.
While there have been reports of these potentially hazardous interactions, there have been no injuries reported to the FDA associated with exposure to cyanide gas as a result of using incompatible media with testing platforms.
The FDA recommends that clinical laboratory staff and health care providers:
- Do not use PrimeStore MTM, Zymo DNA/RNA Shield, Spectrum Solutions Saliva Collection Device, or any other transport media containing guanidine thiocyanate or similar chemicals with the Hologic Panther or Panther Fusion Systems due to a disinfecting step involving bleach that is specific to the testing platform.
- Review the manufacturer's instructions for the testing platform used in your laboratory about which transport media should be used.
- Do not use cleaning agents containing bleach on testing platforms that use guanidine thiocyanate or similar chemicals, either in transport media or sample processing reagents.
- Do not separate transport media tubes from the manufacturer's labeling.
- If you can identify the contents of the tube through associated packaging or information from the distributor, you may place a label on a specimen collection tube that does not have a label identifying the type of transport media inside. If you do not have a label, you may contact the manufacturer to obtain one.
- If you cannot identify the type of transport media in the specimen collection tubes or if you do not know if the transport media contains guanidine thiocyanate or similar chemicals as an ingredient, handle tubes as if they contain guanidine thiocyanate or similar chemicals.
PrimeStore MTM (LH-1-02* and LH-1-03*), Zymo DNA/RNA Shield, and Spectrum Solutions Saliva Collection Device contain a transport medium which maintains patient specimens while they are transported to a laboratory for RNA and DNA testing. These media contain guanidine thiocyanate or similar chemicals, which produces a potentially hazardous chemical reaction that releases cyanide gas when exposed to bleach (sodium hypochlorite) and should not be used in a testing platform, or in laboratory processes, that use bleach. Many laboratories may use bleach in their cleaning or decontamination processes in response to laboratory spills.
Other transport media may contain guanidine thiocyanate or other similar chemicals, and ingredients in transport media may not be listed on individual tubes. If laboratory staff do not know the ingredients in the transport media, they should handle it as though it has guanidine thiocyanate or similar chemicals to avoid a potential reaction. If laboratory staff receive samples in unfamiliar transport media, or transport media without appropriate labeling, they should make sure the media does not contain guanidine thiocyanate or similar chemicals before processing the samples in a testing platform that uses bleach, or before using the samples in a laboratory that regularly uses bleach for laboratory cleaning and decontamination processes.
The FDA is collaborating with manufacturers of transport media and SARS-CoV-2 testing platforms to improve product labeling.
The FDA is working with federal and state health agencies to inform laboratory staff about the risk of exposure to harmful cyanide gas when certain transport media are used with an incompatible testing platform or laboratory process.
The FDA will continue to keep clinical laboratory staff, health care providers, manufacturers, and the public informed of new or additional information.
- What If I Do Not Have...? section on the FAQs on Testing for SARS-CoV-2 page
- PrimeStore MTM decision summary DEN170029
- Longhorn Vines and Diagnostics LLC Client Letter
Reporting Problems to the FDA
The FDA encourages health care providers to report any adverse events or suspected adverse events experienced with transport media and SARS-COV-2 testing sample kits.
- Voluntary reports can be submitted through MedWatch, the FDA Safety Information and Adverse Event Reporting program.
- Device manufacturers and user organizations must comply with the applicable Medical Device Reporting (MDR) regulations.
- Health care personnel employed by organizations that are subject to the FDA's user facility reporting requirements should follow the reporting procedures established by their organizations.
Prompt reporting of adverse events can help the FDA identify and better understand the risks associated with medical devices.
If you have questions about this letter, contact COVID19DX@fda.hhs.gov.