A lumpy, whitish object that exploded and hurt two people cleaning the Charles River has been tentatively identified as sodium metal, and authorities are trying to determine whether it was left over from an annual prank by students at the Massachusetts Institute of Technology.
The 8-inch-long object, which resembled a chunk of Styrofoam, was tentatively identified after an analysis at the state crime laboratory, said Jake Wark, spokesman for the Suffolk County district attorney's office. Two volunteers suffered superficial burns Thursday when they picked up the sodium metal with a 10-foot pole similar to a pool skimmer, said Tom McNichol, president of the nonprofit Charles River Cleanup Boat.
Sodium metal explodes when it is exposed to water. MIT students have a long tradition of welcoming the new school year by stealing a lump of the material from the school's chemistry labs and heaving it into the Charles.
"State Police and the state Department of Fire Services are aware of an annual sodium drop into the Charles River," Wark said, adding that the episode remains under investigation.
"MIT is cooperating fully with appropriate authorities to establish the facts," said Pamela Dumas Serfes, an MIT spokeswoman. She could not say whether a sodium drop took place this year.
The explosion on the Boston bank of the river cost the Charles River Cleanup Boat thousands of dollars in decontamination bills and has hurt the image of an organization that relies on volunteers and donations, McNichol said.
"These kids have caused us some major problems," McNichol said. "What if it wasn't our guys picking it up with a 10-foot pole? It could have been a kid, and he would have lost an arm or an eye."