DHS continues testing on MBTA stations

The Department of Homeland Security and the Massachusetts Bay Transportation Authority continued testing bioterror sensors at train stations on Wednesday using a non-dangerous bacterium.

The researchers are testing the sensors, which rapidly detect biological material, at the Davis, Porter and Harvard stations. The testing will occur in the early-morning hours when the MBTA is not in operation, Patch reports.

Testing on the subway system's Red Line started on August 28 at 1 a.m. Further tests are planned periodically over the next year.

The dead bacterium, bacillus subtilis, is harmless, according to an email from the MBTA. The organism is used in farming as a food supplement for livestock and humans. It is also used as an ingredient in organic dog food.

The original plan proposed by the DHS was to release live bacteria at rush hour in an effort to more closely simulate how an actual attack would take place. The plan was rejected because of potential danger to riders with a compromised immune system, according to Patch.

Biological attacks using the subway system are a major concern for security officials. In 1995, the Japanese Aum Shinrikyo cult released nerve gas on the subway system in Tokyo. The attack left 5,500 injured and killed 12 people.