Liquids, Fumigants, or Foggers: Decontaminating Ricin

By Lahne Mattas-Curry

Line of police tape with emergency responders in the far backgroundYou can’t watch the news lately and not hear the word “ricin.” Letters laced with ricin have been sent to the President, other federal officials, and New York City’s Mayor. And while the letters have not reached their intended recipients, ricin can contaminate mail sorters and buildings.

What is ricin? Where do you even find it? These were the questions I asked when I first heard a letter addressed to the President was contaminated with ricin. From an intensive google search, I learned ricin comes from castor beans. It is extremely toxic (a few particles the size of table salt grains can kill a human) and the effects depend on whether it is inhaled, ingested, or injected.  The ricin that contaminated the letters, in these cases, was in the form of a powder, but ricin can also be used by terrorists as mist, a pellet, or it can be dissolved in water or weak acid, too.

While everyone is deemed safe at this point, an element I wondered about was who decontaminates the mail sorters and equipment the letters came into contact with, or the buildings where it was produced, and how? This is where EPA’s homeland security research comes into play.

While the “who” part depends on where the incident happens, the “how” is being researched day in and day out – looking for the best sampling methods and decontamination techniques.

One focus of homeland security research at EPA examines the efficacy of different decontamination methods, for example, using liquids, fumigants, or foggers. Scientists and engineers have identified ways to contain decontaminants and ways to dispose of the waste after decontamination. Hydrogen peroxide, pH-adjusted bleach, and chlorine-dioxide fumigation decontamination technologies are techniques researchers have tested and found to be successful decontaminants in different scenarios.

Researchers here have also developed a suite of decision support tools to assist in the safe disposal of waste and debris that might be generated during a contamination incident. The research helps decision-makers make the most appropriate choices for each situation and gives them the tools to make sure the environment is safe following an event.

While the health of those who may have been exposed is always first and foremost during a situation like this, responders also want to make sure they can decontaminate effected buildings, rooms, and equipment and mitigate any subsequent exposures. To learn more about EPA’s homeland security indoor and outdoor cleanup research,  please visit:

About the Author: Lahne Mattas-Curry is a frequent blogger covering water issues, but has recently expanded to share how researchers and engineers keep us safe from all the bad stuff, specifically in events of terrorism – chemical, biological, or radiological – or natural events like hurricanes, earthquakes and nuclear accidents.