Bioterror experts say the poison ricin is easy to make, but it's not at the top of the list when it comes bioterrorism threats. The Centers for Disease Control and Prevention considers smallpox, anthrax and botulism far greater threats.

Ricin poisoning is rare and occurs mostly from accidentally chewing castor beans. Ricin is made from the waste left over from making castor oil.

Ricin is widely available and easily produced. The raw materials are all over the world. Castor plants are even sold on eBay.

Ricin can kill if it's inhaled, but the head of American Academy of Clinical Toxicology said it would take hundreds of pounds of ricin to do as much damage as a couple of pounds of anthrax.

That means ricin is most dangerous in small-scale attacks.

The poison is most deadly in small amounts if it's injected. It takes only enough ricin to cover the head of a pin to kill a victim that way.

Symptoms usually start within hours of exposure. A person who breathes it in can experience shortness of breath, fever, or cough, and could eventually end up with respiratory failure.

Ingesting ricin can cause vomiting, diarrhea, dehydration, seizures, and multiple organ failure.

There is no antidote from ricin, so doctors can only treat the symptoms and give supportive care.

If a person who has been exposed to ricin is still alive three to five days later, chances are he or she will make a full recovery.

Additional Resources:

• CDC: All About Ricin
• Questions And Answers About Ricin
• Facts About Ricin