part of the Federal Government, to review and evaluate the available scientific evidence regarding associations between diseases and exposure to toxic substances. (b) Agreement (1) In general The Secretary of Veterans Affairs shall seek to enter into a five-year agreement with the Academies to perform the services covered by this section. (2) Timing The Secretary shall seek to enter into an agreement described in paragraph (1) not later than 60 days after the date of the enactment of this Act. (3) Extension An agreement under this section may be extended in five-year increments. (c) Review of scientific evidence Under an agreement between the Secretary and the Academies under this section, the Academies shall review and summarize the scientific evidence, and assess the strength thereof, concerning the association between exposure to toxic substances during active military, naval, or air service and each disease suspected to be associated with such exposure in the human population. (d) Scientific determinations concerning diseases For each disease reviewed under subsection (c), the Academies shall determine, to the extent that available scientific data permit meaningful determinations— (1) whether an association exists between exposure to toxic substances and the occurrence of the disease, taking into account the strength of the scientific evidence and the appropriateness of the statistical and epidemiological methods used to detect the association