CONCORD, N.H. (AP) — A former Exxon Mobile engineer testified Monday that environmental hazards surrounding the gasoline additive MTBE were widely discussed in water quality and oil industry circles in the mid-1980s, contradicting the state of New Hampshire’s allegations that the oil giant hid its concerns about the product.

Barbara Mickelson was the first witness as lawyers for Exxon Mobile Corp. began presenting their defense against the state’s claim that it is owed hundreds of millions of dollars to clean up groundwater contamination caused by MTBE. Jurors had last week off after spending six weeks hearing the state’s case, and the defense is expected to take just as long presenting its side.