Photo: Andrew Nawrocki

Q I spotted this green Teenage Mutant Ninja Turtles–like ooze on a street corner in the South Loop. Pretty freaky! What are the origins of this mystery goo? Is it toxic?

A This is no St. Patrick’s Day–related Chicago river runoff. The secret of the ooze, to put it in TMNT terms, is that it’s antifreeze that either leaked from a vehicle or was dumped onto the street. The neon liquid won’t turn animals into monstrous martial-arts masters but does pose a lethal threat if ingested by dogs, cats, pigeons or other critters. “It’s not something that’s an epidemic,” says Larry Merritt, spokesman for the city’s Department of Environment, “but if someone calls and reports antifreeze or whatever on the street, we will check it out.” (Call the department’s complaint line at 312-744-7672.) Merritt recommends Chicagoans bring old antifreeze to the Household Chemical and Computer Recycling Facility at 1150 North Branch Street, which properly disposes of the toxic substance by removing the contaminants. More than 30 local businesses recycle antifreeze; for a full list go to earth911.com.

Curious about something around town? E-mail us at chicago@timeoutchicago.com.