KANSAS CITY -- Dow Chemical Co. has gone to trial over allegations it took part in a conspiracy to fix the prices of urethane chemicals, specifically polyether polyols, Bloomberg reports.

Dow was one of several chemical company defendants named in a class action lawsuit in 2005. Sued alongside Bayer AG, BASF SE, Huntsman International and Lyondell Chemical Co., Dow is the only company that has not settled with the plaintiffs, who were purchasers of the companies' products.

The lawsuit alleges that Dow and its competitors began fixing prices for chemicals from 1999 to 2003, at a time when there was excess demand in industry.

Dow has denied the allegations.