Toxic releases are growing again in Maine after years of decline, according to a report by the Environmental Protection Agency.

Toxic chemical releases grew 13 percent in 2004, the report said, and state and industry officials are reviewing the data to determine what happened.

Some of Maine’s largest polluters believe the data is misleading and suggest that the report reflects not increased pollution but improved tracking of pollutants.

“The numbers in Maine are way up but that does not necessarily mean the releases are way up,” said Bill Cohen, a spokesman for International Paper in Jay, the second-largest source of industrial toxins in the report.

But Michael Belliveau of the Environmental Health Strategy Center said there’s cause for concern. The report suggests Maine’s pulp and paper mills aren’t doing enough to reduce releases into the environment, Belliveau said.

“Maine’s industry, particularly pulp and paper, doesn’t appear to be making much progress,” Belliveau said.

The report is the latest annual update of the EPA’s Toxic Release Inventory, which has been compiled since 1988. The updated report, issued this month, is based on data that industries are required to compile and to provide to the federal agency.

In the report, Maine had more toxic releases from industry – 9.6 million pounds – than any other New England state. It is also the only New England state to show an increase.

The state’s paper mills accounted for 7.2 million pounds of chemical releases in 2004, or 68 percent of the state’s total, according to the report.

Food manufacturing ranked second with 2.1 million pounds, nearly all of which is attributed to McCain Foods USA Inc., which has a french fry plant in Aroostook County. A McCain official said the Easton plant complies with all environmental regulations.

Some of Maine’s other top industrial sources – paper mills – are responsible for the sharp overall increase in the 2004 data.