SALEM ? The U.S. Environmental Protection Agency released its latest data Thursday on the release of toxic chemicals and the Salem Harbor Station power plant ranked among the top five polluters.The EPA’s Toxic Release Inventory was made available for 2006, including results categorized by local community as well as a national analysis.The five facilities that reported the largest quantity of on- and off-site environmental releases in Massachusetts and the respective number of chemical pounds were, in order of severity: Dominion Energy’s Brayton Point in Somerset, reporting 1,646,002 pounds; Mount Tom Generating Co. in Holyoke, with 432,217 pounds; Crown Beverage Packaging in Lawrence with 396,950 pounds; Dominion Energy’s Salem Harbor Station in Salem with 369,065 pounds; and Boston Generating Co.’s Mystic Station in Charlestown with 243,696 pounds.Each year, EPA makes the database publicly available. Industries throughout the U.S. are required to report the chemicals they release into the air, water and land.”EPA is continuing to see lower amounts of pollutants being released to New England’s environment,” said Robert W. Varney, regional administrator for EPA’s New England office. “We’re also getting quality data out to the public faster, thanks to more facilities reporting electronically. This helps citizens, communities, industry and our environment.”During 2006, the latest year for which data are available, approximately 27.7 million pounds of chemicals were released in the six New England states, a reduction of 2,560,906 pounds. In Massachusetts, 546 facilities reported in 2006 approximately 7.0 million pounds (a reduction of 667,871 pounds). Approximately 89 percent of releases in Massachusetts were emitted to the air during 2006.Varney noted that reporting under the Toxic Release Inventory does not indicate illegal discharges of pollutants to the environment, nor does the data reflect specific toxicity of the chemicals emitted.The data indicates the top five chemicals released to the environment on- and off-site during 2006 in Massachusetts were: Hydrochloric Acid, 1,624,562 pounds; Ammonia, 662,058 pounds; Zinc compounds, 533,674 pounds; Toluene, 377,311 pounds; and Barium compounds, 346,318 pounds.To search the database, go online to www.epa.gov/triexplorer.