CONCORD, N.H. (AP) – A new report shows the gasoline additive MtBE, which may cause cancer, has been found in drinking water wells throughout New Hampshire.

“The study … documents widespread MtBE contamination throughout the state in both public and private drinking water wells,” said a statement from state Environmental Services Commissioner Thomas Burack.

The highest incidence was in New Hampshire’s most populous counties: Rockingham, Hillsborough, Strafford and Merrimack. Nearly half of the private wells tested in the higher population areas of Rockingham County contained MtBE, the study found.

The study showed a small percentage of the wells tested exceeded health standards for MtBE contamination.

MtBE is a chemical that oil companies added to gasoline supplies from 1979 to January 2007, when the state banned it. From 1995 until the ban, oil companies added greater amounts of MtBE — 10% or more to gasoline sold in the four populous counties.

The additive helped gasoline burn cleaner to meet air pollution standards, but was found to contaminate water.

It can be found in groundwater wherever gasoline is used and has been found to easily escape from underground storage tank systems, Burack said. It travels farther and faster than other gasoline components, and does not easily break down in groundwater.

Overall, the study showed MtBE contamination in roughly 30% of public water supplies in the most populated counties and in 17% of private wells tested there. In Rockingham County, one in three private wells tested had MtBE, while the chemical showed up in one of every two wells tested in highly populated areas.

Public wells at manufactured housing parks showed the highest incidence of contamination, with MtBE detected in 71% of the wells tested. In addition, 40% of large community water systems had MtBE contamination present.

New Hampshire has a health-based drinking water standard of 13 parts per billion for MtBE. Water treatment is required when the standard is exceeded. However, MtBE can cause taste and odor complaints at much lower levels, Burack said. The study showed that a small percentage of the wells tested exceeded the standard.

The Attorney General has sued oil companies and refiners that added MtBE to New Hampshire’s gasoline supplies, trying to get the companies to pay to clean up the contamination.

On the Web:

http://pubs.acs.org/cgi-bin/abstract.cgi/esthag/asap/abs/es071519z.h tml

AP-ES-01-02-08 1456EST