Ricin-laced letters like the ones sent to President Obama and a U.S. senator can be fatal, but they are such inefficient weapons they were more likely intended to disrupt than to deliver a lethal blow, experts said today.
At its most dangerous, ricin can kill a victim six to 12 hours after exposure and there is no antidote. But on a practical level it is very difficult to deliver a killer dose.
In fact, the poison powder has been in the mail before, and it hasn't sickened anyone.
"If you're just trying to piggyback onto the hysteria around the Boston Marathon bombings, you don't have to actually poison anybody," said Dr. Henry Miller, a former director of the Food and Drug Administration's Office of Biotechnology. "You don't have to kill a lot of people just to create terror."
Ricin powder has been in the United States mail twice within the last decade, but no one got sick, said Dr. Christopher Holstege, the chief of medical toxicology at the University of Virginia. In Greenville, S.C., in 2003, a package containing ricin was found with a note that its sender would poison the water supply. In 2004, ricin was discovered in an envelope in then-Senate Majority Leader Bill Frist's mailroom in Washington DC.
Ricin is a protein toxin made from ground up and purified castor beans, said John Clements, chair of Tulane University department of microbiology and immunology. An amount equal in size to a few granules of salt could be enough to kill an adult, but it takes days to make.
Ricin victims typically die of organ failure within six to 12 hours of exposure because the poison stops cells from synthesizing proteins, effectively killing them, Holstege said. Symptoms can vary depending on whether the victim inhaled or ingested the poison, and there is no cure.
Because Ricin is not alive, it does not spread from cell to cell or person to person, said Miller, who works at Stanford University's Hoover Institution.
Clements said the "robust" system of post office mail checks – and the fact that political figures rarely open their own mail – means it's unlikely that poisoned envelopes can reach intended targets.
"It's so inefficient and could have so many places fail, that I don't even know why you'd bother. Nobody who was the intended target got anthrax," he said.
In 2001, letters containing anthrax powder caused 22 anthrax infections, killing five people. Those infected included postal workers and a 7-month-old baby, but none of them were the addressees. Instead, the tiny anthrax molecules slipped through the pores in the envelopes to infect unintended targets, Clements said, adding that the ricin particles don't seem to have been small enough to do that.
Unlike anthrax, which is a disease, Clements said ricin is relatively simple for a chemist to make in small amounts, considering crude instructions are available on the internet. But the ricin maker would also be at great risk of poisoning himself.
To make ricin lethally inhalable, its makers would likely have to break the poison down into particles tiny enough to reach the lungs' alveoli structures, Holstege said. A smaller particle would mean it came from a more advanced lab, which will be an important clue for investigators, he said.
Clements said the ricin attack isn't biological warfare. It's bioterrorism.
"Think weapon of mass disruption rather than weapon of mass destruction," he said. "You don't need to kill a lot of people to scare a population. In that case, you don't need sophisticated delivery and dispersal systems, just a press and politicians more interested in spreading fear than information."