If a state safety member retires for service before attaining age 55, or, in the case of the member who continues subject to the current and prior service pension provision for retirement of warden and forestry members at age 60, his or her prior and current service pensions shall be reduced to that amount that the value of the pensions as deferred to age 55, or age 60, respectively, will purchase at the actual age of retirement on the basis of the mortality tables and actuarial interest rate in effect on December 1, 1970, under this system with respect to those

members.