Letters containing ricin sent President Obama and Mayor Bloomberg

Letters testing positive for ricin were recently sent to President Obama and New York City Mayor Michael Bloomberg .

The letter addressed to Obama was intercepted on Friday at the U.S. capitol's off-site mail facility in Washington, D.C., and later tested positive for ricin. A similar letter was sent to Mayor Bloomberg.

This event comes after letters with ricin were discovered in April. Three letters, sent to President Obama, Senator Roger Wicker and Justice Court Judge Sadie Holland, were intercepted before they could reach their targets. These recent events demonstrate the need for technologies able to detect CBRN threats.

Universal Detection Technology is a company that manufactures ricin detection kits. Its first responder detection kits have been previously used by law enforcement officials in similar events.

Ricin is a highly toxic substance that can be derived from castor beans. Small doses, as little as 500 micrograms, can kill an adult.

"Ricin has become the toxin of choice for fringe elements seeking to spread their message of fear," Jacques Tizabi, UNDT's chairman and CEO, said. "Thankfully our nation's first responders are equipped with the equipment to detect and neutralize any harm from these tainted letters."