Diarrhetic shellfish poisoning (DSP) toxins produced by the dinoflagellate Dinophysis can cause severe gastrointestinal illness in humans. Dinophysis harmful algal blooms cause the closure of shellfish beds and temporary pauses on harvesting to ensure shellfish safety, resulting in substantial economic losses. Routine, accurate quantification of DSP toxins in shellfish tissue, integrated into a comprehensive state monitoring and fishery management framework under the National Shellfish Sanitation Program, is essential for public safety. This project will increase the number of laboratories nationwide that can accurately quantify and monitor diarrhetic shellfish poison toxins in shellfish.
Why We Care
Diarrhetic Shellfish Poisoning (DSP), caused by okadaic acid and its analogues, poses a growing threat in U.S. coastal waters. Accurate, routine quantification of DSP toxins in shellfish is essential for public safety. The U.S. National Shellfish Sanitation Program (NSSP) adopted “The Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) Method for the Determination of Diarrhetic Shellfish Poisoning (DSP) Toxins in Shellfish” in 2017 as the first method approved to test DSP toxins in clams harvested from U.S. waters.
State shellfish regulatory laboratories have identified challenges related to implementation and transferability of this analytical method that have limited its practical use. Analytical approaches often need adjustment to accommodate different instrument manufacturers and their configurations, and can require adaptation to ensure consistency across laboratories. Additionally, this method can only be used to detect DSP toxins in clams under the NSSP — additional “matrix extension” studies are required for other commercial shellfish species. This proposal aims to develop a harmonized LC-MS/MS protocol to increase the number of laboratories capable of reliably quantifying DSP toxins in clams and other shellfish species to ensure safe seafood consumption.
What We Are Doing
This project will generate a harmonized LC-MS/MS standard operating protocol (SOP) for the quantification of DSP toxins in shellfish that allows a broader range of instrument configurations and analytical procedures than the current method, while maintaining sufficiently high-quality control criteria for regulatory use under the NSSP.
The objectives of this project are to:
- Compile and submit a preproposal describing the tests that will be conducted for a single laboratory validation (SLV) study, with results to be submitted to the Interstate Shellfish Sanitation Conference (ISSC) for evaluation.
- Collect the appropriate shellfish samples with naturally incurred DSP toxins from relevant regions in U.S. waters.
- Prepare a series of DSP toxin-spiked samples, as required by the ISSC SLV protocol.
- Perform the SLV analyses at the participating laboratories to determine accuracy/trueness, precision and recovery, specificity, working and linear range, limit of detection, limit of quantitation ruggedness, matrix effects, and comparability.
- Compile results in a proposal to the ISSC and corresponding checklist that encompasses the SOP of the participating laboratories.
- Inform and educate state shellfish safety authorities of the analytical options available for routine, NSSP-approved LC-MS/MS analyses of DSP toxins in their shellfish monitoring and management strategies.
- Develop a database of shellfish DSP toxin content from the U.S. waters sampled in this study. This information will be compiled to review regional variability in the DSP toxin profiles, temporal trends in levels of toxicity and DSP toxin distribution.
Chromatographic separation and targeted quantitation of DSP toxins using LC-MS/MS multiple reaction monitoring. Credit: Whitney Stutts and Jonathan Deeds, ISSC Proposal No. 17-103.
Benefits of Our Work
This project will increase the number of laboratories that can provide accurate analytical quantification of DSP toxins, using NSSP-approved methodology, to regulatory decision makers at the state and federal level who are involved in ensuring the safety of shellfish produced and sold for human consumption. The application of LC-MS/MS for DSP quantification is fundamental to the existing shellfish monitoring strategies in several U.S. states.
Broadening the scope of the LC-MS/MS method will allow a greater number of laboratories to provide regulatory-level analysis. A harmonized LC-MS/MS for DSP toxin analysis will be of most value to those responsible for public safety: shellfish managers, aquaculture producers, and seafood wholesalers.
Dr. Stephen Archer of the Bigelow Laboratory for Ocean Sciences leads this project. Other principal investigators include Dr. Jonathan Deeds (U.S. Food and Drug Administration), Shelley Lankford (Washington State Department of Health), Kohl Kanwit (Maine Department of Marine Resources Public Health Bureau), and Jill MacLeod (Maine Department of Marine Resources Public Health Bureau).
The project is funded through the NCCOS Prevention, Control, and Mitigation of Harmful Algal Blooms (PCMHAB) Program.