UPDATE 3:15 pm: Zeon Chemical's release of 12 pounds of butadiene yesterday morning was accidental. Zeon Vice President of Operations Bob Barlow told me that a gasket leak caused the release. The reportable amount of butadiene is 10 pounds, so this was just over the reportable quantity.Jody Johnson of the Louisville Emergency Management Agency got back to me too, and said because the leak was indoors and wasn't picked up on air monitors outside the building, the EMA didn't believe there was any risk to the neighborhood. Even so, a Code Red alert was issued to neighbors of the plant to let them know what was going on.Zeon will prepare a report about the causes of the leak and how to prevent similar instances in the future, and send it to various Metro and state agencies.UPDATE 2:20 pm: Apparently, no one is really sure what happened with the butadiene release at Zeon. The Air Pollution Control District is checking into the release, to see if it violated any emission standards, and spokesman Tom Nord told me that the Louisville Emergency Management Agency is requiring the company to file a report within 60 days outlining the cause of the release and how future instances might be prevented. But at the EMA, spokeswoman Jody Johnson said she couldn't confirm that, and wasn't even sure the release was an accident.I'm waiting to hear back from Zeon Chemical and the EMA to see what actually happened at the plant yesterday.ORIGINAL POST: There was a small chemical spill in Rubbertown yesterday, as WAVE3 reported. The spill was at Zeon Chemical's plant on Bells Lane.What the WAVE3 story doesn't include is exactly what chemical was spilled. According to Steve Tedder, the spokesman for the Metropolitan Sewer District, about 12 pounds of butadiene was released. (MSD and the Lake Dreamland Fire Department responded to the spill, but it was an air release, and the MSD only deals with spills that affect the sewers.)1,3 butadiene is listed as a known carcinogen by the Environmental Protection Agency and the Agency for Toxic Substances Disease Registry. It's present in vehicle exhaust, and is used in the production of rubber. Butadiene is regulated under the Air Pollution Control District's Strategic Toxic Air Reduction (STAR) program.No one was injured by the chemical release, but any spill is a concern for local residents who often report smelling odd odors. Groups like Rubbertown Emergency ACTion have also questioned what the cumulative effects of releases from all the Rubbertown companies could have on human health.