1. Skip to navigation
  2. Skip to content
  3. Skip to secondary content
  4. Skip to sidebar


  • More Sharing...

The Scientists of Santiago

Dr. Benjamín Suárez-Isla

Dr. Benjamín Suárez-Isla, Director of Laboratory of Marine Toxins, University of Chile. (Photo credit: K. Hansen / IAEA) See photo gallery

Story Resources

Dr. Benjamín Suárez-Isla, Director of Laboratory of Marine Toxins, University of Chile, has been researching the Harmful Algal Bloom (HAB) phenomena for 15 odd years. With technical cooperation from the IAEA and Chilean Government, he recently set up a marine toxin laboratory on the remote Island of Chiloé. At the lab, technicians are taught how to use the Receptor-Binding Assay (RBA) to quickly warn of a toxic algae outbreak in Chile's prime fishing region.

How the RBA Monitoring Tool Works

The RBA is not a new science. The nuclear technique is widely used in medicine for example, to measure hormone levels. The technique also is not the only one scientists are targeting as an alternative to the mouse bioassay for monitoring HAB toxins.

Dr. Suárez-Isla explains the RBA procedure works by mixing a shellfish sample with a "marker" - a radiolabelled saxitoxin, which is basically a radioactive version of the same family of poisons found in the shellfish. When the mixture is exposed to a small amount of rat brain, if the sample is poisonous, the radioactive toxin and poison compete with each other to bind to nerve cells receptors in the brain. The radioactive toxin will be displaced or "bumped off" its receptor by any poison present in the shellfish, and its total radioactivity reduced. By measuring amounts of radioactivity left in the sample, scientists can pinpoint exactly how low or high toxic concentrations in marine food or seawater samples are.

"It is far more sensitive than the standard mouse assay," Dr. Suárez-Isla says. "Health authorities err on the side of caution when it comes to closing coastal areas - which infuriates the producers," he said. The one thing seafood producers and authorities agree on is that a faster, more precise, detection tool like the RBA is needed.

"On the Monday before the outbreak in Chiloé, the toxicity level shown was zero, but by the following Monday it was well above safe limits. The RBA would have given authorities much earlier warning of the pending outbreak and better information on which to act," Dr. Suárez-Isla said.

"Businesses are at risks, lives are a risk. Any technique that could decrease the response time and warn when waters are safe, or unsafe, is relevant", says Mr. Juan Perez, a local Mayor in the Chiloé region.

The IAEA through a Technical Cooperation project provided the marine toxins lab in Chiloé with the equipment technicians need to observe the seas using the RBA. The information now gives them a more precise map of waters that are safe and those might become, or are, contaminated. FONDEF-Conicyt grants from the Chillian Government awarded to Dr. Suárez-Isla and the University of Chile also helped to establish the laboratory, which will serve as a reference centre to share information with other end-user laboratories. Daily observations made at the lab will be recorded on a website that allows fishermen, health authorities and others to track waters for signs of toxic algae.

The more humane monitoring method is also welcomed. Health regulator Dr. Ramon Andrade points to a quarter-filled garbage bin of dead mice. He says each week about 1000 live mice are currently used to monitor Chiloé´s waters for HAB. Some countries have banned imports on products tested on live animals. It makes for a complex export system when the live mouse assay is the essential certification need to export seafood.

The IAEA is spearheading efforts to change the "gold star" export standard from the mouse assay to the RBA. To this end the Agency has invested over $2 million in regional projects, facilitated international collaboration between regulatory authorities and national institutes using the RBA, and identified the necessary steps to undertake the certification.

The road of red tape has been long, and, for a time, sidetracked by events. In late 2002, work towards certification hit a snag, when fears linked to the September 11, 2001 terrorist attacks in America, placed saxitoxin near the top of a list of chemical warfare agents the US was tracking. The only commercial company that produced the radiolabelled saxitoxin (needed for the RBA) stopped manufacturing it.

The IAEA led successful efforts to restart production of radiolabelled saxitoxin and get it off the chemical hit list. The steps led to a gold mine of sorts. For the next three years, the needed chemical will be supplied free of charge to the IAEA by the United States Food and Drug Administration for distribution to countries learning to apply the RBA technique. "It is very generous when you consider the commercial cost is upwards of $40 million," Dr. Kerry Burns, Head of Chemistry Unit at the IAEA Seibersdorf Laboratories, said.

The certification process starts this year, with predictions that RBA will become the export standard a bit more optimistic. The forecast is about two to five years if things go smoothly.

Next: The Algae´s Toxic Brews »