The incident occurred at around midnight, when the company says "pressure release from the outer chamber of a carbon filter" injured three Aesica employees and landed them in hospital.
While two have since been released, one employee is still under medical care and has been transferred to a specialist clinic to undergo treatment.
The carbon filter responsible for the blast is used in Aesica's processes to remove colour from products, with the Ponders End facility operating 24-hours a day.
"The incident was contained within the building where the event took place and no other parts of the site or local area were affected," the company said in a statement released this morning.
"A full investigation has been launched and will be completed as soon as possible."
The Ponders End chemical manufacturing facility has a 300-ton-per-year capacity, and was bought from Merck Sharp & Dohme (MSD) just over a year ago.
The acquisition also brought Aesica a multi-year supply agreement to provide MSD with intermediates and active pharmaceutical ingredients for a number of years.
Aesica also bought an Abbott site in Queenborough in September this year (bringing another supply agreement in place until 2012), and in August also announced a new small scale pilot plant at its site in Cramlington, Northumberland.
The company was formed in 2004 following a management buyout form global chemical company BASF.
The firm was unavailable to comment further on last night's incident prior to going to press.
