More evidence has linked Agent Orange, an herbicide that was commonly used during the Vietnam War, to bladder cancer and thyroid problems, a report found.

For this Institute of Medicine (IOM) report, researchers reviewed scientific data that had examined the potential effects that the chemical had on bladder cancer, hypothyroidism and the birth defect spina bifida, which occurs when a baby's spinal cord has not developed properly. All of the literature was published between Oct.1, 2012, and Sept. 20, 2014.

The researchers concluded that there is "limited or suggestive" evidence that exposure to Agent Orange might lead to bladder cancer and thyroid problems. These two health conditions were previously categorized under "inadequate or insufficient" evidence.

For spina bifida, the researchers did not find a strong association between the birth defect and paternal or maternal exposure to Agent Orange. This categorization for this condition was changed from "limited or suggestive" to "inadequate or insufficient."

This is the second time that a condition linked to Agent Orange has been moved to a lower category. In 1998, the IOM reviewed a 1994 report that had categorized the skin condition porphyria cutanea tarda as "sufficient" in regards to its association with Agent Orange. The revision regrouped porphyria cutanea tarda as "limited or suggestive."

The researchers also looked at the link between Agent Orange and the neurodegenerative brain disease Parkinson's. They concluded that Vietnam War veterans who have symptoms of Parkinson's but have not been diagnosed with the condition "should be considered eligible under the presumption that Parkinson's disease and the veterans' service are connected."

Upon finalizing this study on Agent Orange, the committee has created a list of recommendations regarding the well-being of Vietnam veterans. The committee is advising the U.S. Department of Veterans Affairs to continue to conduct epidemiologic studies, create new protocols to further analyze the link between paternal exposure and adverse health conditions in offspring, and design a study investigating dioxin exposure in humans.

The committee also wants the VA to improve how it monitors service-related health problems in all military members.

Agent Orange was used from 1962 to 1971 by the U.S. military to clear out terrain in Vietnam during the war. Congress later passed the Agent Orange Act of 1991 to investigate whether or not Agent Orange and other chemicals caused long-term health problems for the soldiers. This report was the final one ordered under the Act.

The report was sponsored by the VA.