JEFFERSON CITY, Mo. — Missouri Sen. Claire McCaskill on Tuesday rolled out legislation aimed at helping World War II veterans she said were exposed to mustard gas by the military, a practice a daughter of one Missouri veteran said led to chronic health issues for her father.

McCaskill’s bill would require the Veterans Affairs Department and the Defense Department to reconsider disability benefits denied to those who claimed the testing caused health problems. McCaskill’s office said the military tested the effects of mustard gas and the blister agent lewisite on about 60,000 veterans by the end of WWII. McCaskill’s staff estimates a couple hundred participants could still be alive.

Those tested were sworn to secrecy until 1991. The Democratic senator said the VA has denied about 90 percent of health claims.

The legislation also would require the VA and the Pentagon create a new policy to process future benefit claims related to mustard agents.

Tuesday, the VA said that full body mustard gas exposure might have caused disabilities. The VA plans to send letters in June to veterans who participated in testing with a number to call for help.