Biomonitoring Methods for Toxins
Investigation: Brevetoxin Exposure in Marine Animals
Brevetoxin (PbTx) is produced by the dinoflagellate Karenia brevis and is known for causing “red tides” along the gulf coast of Florida. Brevetoxin is a health risk to humans and marine organisms, including protected marine mammals such as manatees and dolphins. In order to biomonitor these populations for brevetoxin exposure, a method for toxin detection at very low concentrations is being optimized. This project focuses on both the use of blood collection cards as a means of blood sample storage and the optimization of the direct enzyme-linked immunosorbant assay (ELISA) format for detecting brevetoxin and its metabolites in dried blood matrices.
Blood collection cards, widely used for human newborn testing, are a way to store blood samples collected from animals and humans suspected to have been exposed to PbTx. Cards have been distributed to researchers in the field through our Analytical Response Team. Blood samples collected as 100 ul spot aliquots are shipped to the Marine Biotoxin Program for toxin analysis, where the dried blood is extracted and amount of toxin is quantified. Laboratory experiments with mice exposed to low doses of brevetoxin have shown that non-symptomatic animals can have detectable blood levels of PbTx within one hour post dosage, and for as long as 12 days after exposure, when analyzed by radioimmunoassay (RIA) (see article http://www.nccos.noaa.gov/news/press/nccos/100203.html.) One purpose of our research is to similarly detect PbTx levels in non-symptomatic marine animals in areas historically known for red tides, such as the Gulf of Mexico.
In an effort to lower the detection limit, collaborating researcher Dr. Lyn Briggs of AgResearch (New Zealand) has optimized a direct ELISA format , which has at present a 10-fold lower limit of detection that the RIA. By being able to measure low quantities (<1ng/ml) in animal blood, baseline levels of PbTx exposure can be established and used not only as a possible predictive measure of harmful algal bloom (HAB) formation, but also allow for proactive management of possible impending HAB events. It also gives us the capability to determine whether an animal has been previously exposed, even if the water shows no indications of a HAB, as the ELISA can also detect metabolites of PbTx. Having this sensitive ELISA for detection in conjunction with the ease of sample collection and storage using blood collection cards will enable us to better monitor the health of animals in areas historically known for red tides. By working to optimize the ELISA format, we are working to lower detection limits in blood and extend the detection time even further than what is currently possible.
Personnel
Publications
- Woofter, R.T., Brendtro, K, and Ramsdell, J.S. (2005). Uptake and elimination of brevetoxin in blood of striped mullet (Mugil cephalus) after aquatic exposure to Karenia brevis. Environ Health Perspect. 113(1):11-16.
- Woofter, R.T., Bottein Dechraoui, M.Y., Garthwaite, I., Towers, N.R., Gordon, C.J., Cordova, J. et al. (2003). Measurement of brevetoxin levels by radioimmunoassay of blood collection cards after acute, long-term and low dose exposure in mice. Environ Health Perspect. 111:1595-1600.
- Fairey ER, Shuart NG, Busman M, Moeller PD, Ramsdell JS. (2001).
Biomonitoring brevetoxin exposure in mammals using blood collection cards. Environ Health Perspect. 109(7):717-20.
