Because of continuing uncertainty about the long-term health effects of the sprayed herbicides on Vietnam veterans, Congress passed the Agent Orange Act of 1991. The legislation directed the Secretary of Veterans Affairs (VA) to request the Institite of Medicine to perform a comprehensive evaluation of scientific and medical information regarding the health effects of exposure to Agent Orange and other herbicides used in Vietnam to be followed by biennial updates. The 2010 update recommends further research of links between Vietnam service and specific health outcomes, most importantly COPD, tonsil cancer, melanoma, brain cancer, Alzheimer's disease, and paternally transmitted effects to offspring.