We have developed a method to monitor the exposure of mammals to brevetoxins. This sampling involves collecting whole blood, applying the blood to a ? inch diameter circle on a specially prepared blood collection card and allowing it to dry. This sample collection method has been widely employed for routine diagnostic and genetic testing of newborns. Collection instructions, cards and mailing envelopes are available without charge through our website at: http://www.chbr.noaa.gov/crpage.html. The blood spots are extracted in the laboratory and total brevetoxin activity quantified using high throughput receptor binding assay and specific brevetoxin congeners analyzed by liquid chromotragraphy-tandem mass spectrometry. Toxicokinetic characterization has been conduced with laboratory mice. Mice were treated with 180 m g/kg brevetoxin-3. Whole blood was collected at time points between 0.5 and 24 hours of brevetoxin exposure and 0.1 ml was spotted on filter paper cards. Brevetoxin activity as determined by receptor assay increased between 0.5 and 4.0 hours and was decreased, yet detectable 24 hours after brevetoxin exposure. Tandem mass spectrometry was used to provide confirmation of brevetoxin-3. The mass spectrometry results paralleled those of receptor assay for time points between 0.5 and 4.0 hours exposure. However, brevetoxin-3 was not detected at 24 hours suggesting metabolism to another biologically active form of the toxin. We anticipate that this approach will provide a method to biomonitor for brevetoxins in living marine resources, protected species, and humans and are evaluating this biomonitoring method for other marine toxins as well.