By Valerie Volcovici

WASHINGTON, Sept 7 (Reuters) - The U.S. Environmental Protection Agency is preparing for Hurricane Irma's landfall on the U.S. East Coast by securing vulnerable toxic waste sites and easing gasoline standards to ensure steady fuel supplies, its chief told Reuters on Thursday.

EPA Administrator Scott Pruitt declined to say whether he believed claims by scientists that the second powerful storm to affect the United States in two weeks may have a link to warmer air and water temperatures resulting from climate change.

"The most we can do is help people in these areas by monitoring drinking water and respond to real and tangible issues," he said in a brief telephone interview.

Hurricane Irma is expected to make landfall in Florida as early as Friday after slamming Caribbean islands with 185 mph winds, only days after Hurricane Harvey triggered record flooding in Texas that killed scores of people.

The EPA said has issued waivers on certain federal requirements for the sale, production and blending of gasoline to avoid supply shortfalls in the aftermath of Harvey and as Hurricane Irma approaches Florida.

Pruitt said he spoke with Florida Governor Rick Scott about potentially issuing more waivers on gasoline requirements if the need arises after Irma.

"EPA will grant additional waivers if requested," he said.

He said the agency is also evaluating 80 Superfund toxic waste sites from Florida to North Carolina to identify those at risk of flooding.

The EPA has yet to finish assessing the impact of Harvey on Texas Superfund sites - heavily contaminated former industrial zones - amid widespread flooding. On Saturday, the agency said 13 sites were flooded or damaged, but the full impact on surrounding areas was not immediately clear.

Pruitt said the agency is also continuing to seek additional information about explosions last week at French chemical company Arkema's flooded plant in Crosby, Texas, which sickened more than a dozen law enforcement personnel and prompted an evacuation of the surrounding area. (Reporting by Valerie Volcovici; Editing by Cynthia Osterman)