Washington ? Sixteen years after the Persian Gulf War ended, more than 1 in 4 of those who fought remain seriously ill with medical problems ranging from severe fatigue and joint pain to Lou Gehrig’s disease, multiple sclerosis and brain cancer, the chairman of a congressional advisory committee testified Tuesday.

But even as more is learned about what’s now called Gulf War Veterans Illness, the Defense Department and the Department of Veterans Affairs remain in virtual denial about its causes and have been slow to offer treatment, said James Binns, the head of the research advisory committee on the disease.

“This is a tragic record of failure, and the time lost can never be regained,” Binns told the Senate Veterans’ Affairs Committee. “This government manipulation of science and violation of law to devalue the health problems of ill veterans is something I would not have believed possible in this country until I took this job.”

Pentagon and VA officials defended their approach to studying and treating the illness, saying they’re taking it seriously, funding clinical and other research, and are committed to ensuring that Gulf War veterans receive needed care.

“Veterans who report health problems are definitely ill,” said Michael Kilpatrick, the Defense Department’s deputy director for force health protection and readiness programs. “However, they do not have a single type of health problem. Consequently, these veterans have to be evaluated and treated as individuals.”

Though the focus was on the earlier Gulf War, concerns hovered over the hearing that those now fighting in Iraq might face similar medical problems.

Fifteen percent to 20 percent of those who’ve fought in Iraq recently are returning with “ill-defined” medical symptoms, Kilpatrick said. He didn’t elaborate.

Of the 700,000 or so U.S. troops who served in the Persian Gulf War, 175,000 to 200,000 are sick, Binns said.

Others who testified said that in addition to the pre-deployment vaccines, the health problems that Gulf War veterans experienced might have been caused by exposure to the depleted uranium used in munitions and armor, low-level nerve agents such as sarin that were released when a large weapons depot was destroyed, and smoke from more than 600 burning oil wells in Kuwait.

Pentagon and VA officials long have linked Gulf War Veterans Illness to battlefield stress and other related psychological disorders.

“That’s garbage,” Binns said. He said the Pentagon had cut important research programs associated with the illness.

The VA has conducted more than 330 projects associated with the health problems of Gulf War veterans. Because of “persistent concerns,” the agency will launch a study next year of possible links between the veterans and brain cancer and multiple sclerosis, said Joel Kuppersmith, the VA’s chief research and development officer.

“VA’s commitment to funding clinical trials to identify new therapies for ill Gulf War veterans continues to this day,” he said.

Kilpatrick said effective therapy for the veterans’ health problems was available, including treatment for those with chronic, unexplained symptoms.