It is agreed that: (1) With respect to operations in a State designated in item 3 of the declarations, the unqualified term "workmen's compensation law" includes part C of title IV of the Federal Coal Mine Health and Safety Act of 1969, 30 U.S.C. section 931 - 936 , and any laws amendatory thereto, or supplementary thereto, which may be or become effective while this policy is in force, and definition (a) of Insuring Agreement III is amended accordingly; (2) with respect to such insurance as is afforded by this endorsement, (a) the States, if any, named below, shall be deemed to be designated in item 3 of the declaration; (b) Insuring Agreement IV(2) is amended to read "by disease caused or aggravated by exposure of which the last day of the last exposure, in the employment of the insured, to conditions causing the disease occurs during the policy period, or occurred prior to (effective date) and claim based on such disease is first filed against the insured during the policy period."
20 C.F.R. §726.203