WASHINGTON, D.C. -- Two Virginia senators are teaming up to help vets who did their duty decades ago and who are now paying the price.

Senators Mark Warner and Tim Kaine are pushing the V.A. to expand its list of which Vietnam veterans who receive treatment and benefits related to exposure to Agent Orange.

During the war, the United States sprayed an estimated 20 million gallons of chemical herbicides and defoliants collectively known as Agent Orange on Vietnam, Laos and Cambodia.

The effects on veterans more than four decades later have been well-documented: increased rates of cancer, including acute and chronic leukemia and Hodgkins and non-Hodgkins lymphoma, as well as nerve, digestive, skin and respiratory disorders.

Yet, many who served on Navy ships in the vicinity are ineligible for help from the Department of Veterans Affairs.

That's because V.A. policy states that "Blue water veterans are not presumed to have been exposed to Agent Orange or other herbicides unless they set foot in Vietnam or served on ships that operated on the inland waterways" between 1962 and 1975.

Virginia Senators Mark Warner and Tim Kaine want change. They've joined 12 other senators in sending a letter to V.A. Secretary Robert McDonald to administratively change what they call "inconsistent and burdensome regulations."

"Regardless of whether they served on land or at sea, those who've fallen victim to Agent Orange deserve access to the same benefits and compensation," said Warner. "We owe these great defenders of our liberty no less."

"There's nearly 4,000 in Virginia who served on ships, in bays, and harbors and estuaries, as well as in the territorial waters within 12 miles of the Vietnamese coast who are suffering from Agent Orange," said Kaine. "And so, is it a surprise that some of these blue water vets have Agent Orange exposure? Absolutely not."

A spokesman at the Hampton V.A. told 13News Now: "Local facilities make no determinations on Agent Orange. Veterans who wish to be considered for Agent Orange related compensation must file a full claim like all other Veterans."