The compound was used to scale up the production of one of Merck's experimental vaccines, but when the scale-up was abandoned, operators at the vaccine research pilot plant simply poured it down the drain.
As a result, the discharge is believed to have entered the Upper Gwynedd wastewater treatment plant through its sewage collection system, where it interacted with chlorine and emerged in the Wissahickon Creek, after which the released cyanide killed more than 1,000 fish.
The U.S. EPA is investigating to establish the extent of the pollution, estimated to be between 2 to 8 miles downstream, although health advisories to avoid recreational contact with the creek have been lifted.
The June 13 discharge was not in accordance with Merck's protocols for proper waste disposal. Normally, the discarded liquid would be sent to a pretreatment plant at Merck's West Point site for minimal processing followed by more processing at the municipal facility and then released to the sewer.
Merck spokeswoman Connie Wickersham described the incident to In-PharmaTechnologist.com as "a human error of fairly good-sized proportions."
According to Wickersham, "Disciplinary action against some staff is pending, and we expect our internal investigations to lead to such action being taken."
An EPA spokeswoman told In-PharmaTechnologist.com that, when the agency completes the investigation, Merck could be fined up to $32,500 per day per violation in civil penalties.
