After years of battling the Veterans Affairs Department for health care and compensation for illnesses related to Agent Orange exposure from aircraft flown after the Vietnam War, a group of up to 2,100 Air Force personnel and reservists finally will receive service-connected benefits.

VA announced Thursday it will expand eligibility for benefits to Air Force members who flew in C-123 aircraft after they were used in Vietnam to spray the toxic herbicide.

The move could provide health care and disability payments for 1,500 to 2,100 former service members, some of whom are suffering illnesses listed among the 14 presumed to be related to Agent Orange exposure.

Earlier this year, the Institute of Medicine concluded that the veterans had been exposed to dioxins in Agent Orange while flying the aircraft after they had been used in Operation Ranch Hand.

The report's conclusions were similar to those reached by another federal agency in 2012.

But VA has insisted for years that trace amounts of dioxin on internal aircraft surfaces were not "biologically available for skin absorption or inhalation because dioxin is not water- or sweat-soluble and does not give off airborne particles."

VA paid multiple consultants and the Institute of Medicine more than $1 million to study the issue, all the while denying claims or questioning their validity.

At one point, Alan Young, a consultant hired by the Veterans Benefit Administration to study possible exposure on the aircraft, labeled the airmen seeking compensation "freeloaders" and said the only reason the reservists were seeking presumptive compensation is so they could "cash in on tax-free money for health issues that originate from their lifestyles and aging."

"There was no exposure to Agent Orange or the dioxin but that doesn't stop them from concocting exposure stories hoping some congressional member will feel sorry for them," Young wrote in an email in 2011.

But Air Force documents dating as far back as 1994 noted that tests on at least one C-123 aircraft came up positive for dioxin; in fact, the Air Force destroyed 18 of the aircraft in 2010, smelting them out of concerns about potential liability for Agent Orange, according to service documents.

Still, it took years for VA to do an about-face. But now that has happened, according to the newly published regulation. Veterans will be eligible to file claims starting Friday.

VA Secretary Bob McDonald called the personnel a "deserving group of Air Force veterans and reservists," saying that ruling their illnesses are service-connected is "the right thing to do."

"We thank the IOM for its thorough review that provided the supporting evidence needed to ensure we can now fully compensate any former crew member who develops an Agent Orange-related disability," McDonald said in a statement released Thursday.

Under the new rule, flight, medical and ground maintenance crew members who served on C-123s are presumed to have been exposed and for any reservist who is ill, the exposure is presumed to have occurred while they were training, making them eligible for VA benefits including disability compensation, medical care, dependency benefits, indemnity compensation and burial.

Affected reservists may have served in these units from 1969 to 1986: the 906th and 907th Tactical Air groups or 355th and 356th Tactical Airlift squadrons at Lockbourne/Rickenbacker Air Force Base, Ohio; the 731st Tactical Air Squadron and 74th Aeromedical Evacuation Squadron, Westover Air Force Base in Massachusetts; and the 758th Airlift Squadron, Pittsburgh.

Some active-duty personnel may be eligible as well. Those who served in a regular Air Force location where a contaminated C-123 was assigned and who had regular contact with the aircraft and now have an Agent Orange-related illness are encouraged to apply for benefits.

Retired Air Force Maj. Wes Carter, a former C-123 officer who has led the charge for health benefits and compensation for C-123 veterans, called the VA decision "a relief" that is unfortunately "tempered by the grief felt for lost comrades."

Carter remains outraged that VA ignored conclusions in the 2012 report from the Centers for Disease Control and Prevention's Agency for Toxic Substances and Disease Registry that swabs taken of the planes in 1994 tested 182 times higher for dioxin than the screening values established by the Army Center for Health Promotion and Preventive Medicine.

Those samples represented a 200-fold excess cancer risk.

Carter is also angered the Veterans Benefits Administration ignored an email from the Defense Department's Joint Service Records Research Center in 2013 that contained information concluding that at least one of the aircraft tested in 1994 came up positive for dioxin.

"Every medical and scientific fact that convinced the Institute of Medicine of our Agent Orange exposures in 2014 had been presented to the VA years earlier but was ignored. This is wrong," Carter wrote in an email.

"We ask Secretary McDonald and [Under Secretary Allison] Hickey for their careful review of VA actions to insure that toxic exposure veterans never again face such an unhappy struggle," Carter said.

Claims will not be awarded retroactively. Individuals with questions related to herbicide exposure on C-123 aircraft can call VA's special C-123 Hotline at 800-749-8387 or e-mail VSCC123.VAVBASPL@va.gov, VA said.