The permit provided in RCW 69.06.010 or 69.06.070 shall be valid in every city, town and county in the state, for the period for which it is issued, and no other health certificate shall be required of such employees by any municipal corporation or political subdivision of the state. The cost of the permit shall be uniform throughout the state and shall be in that amount set by the state board of health. The cost of the permit shall reflect actual costs of food worker training and education, administration of the program, and testing of applicants. The state board of health shall periodically review the costs associated with the permit program and adjust the fee accordingly. The board shall also ensure that the fee is not set at an amount that would prohibit low-income persons from obtaining permits.