A member of the planning commission shall not participate in any commission proceeding or action in which any of the following has a direct or substantial financial interest: the member or member’s spouse, brother, sister, child, parent, father-in-law, mother-in-law, any business in which the commissioner is then serving or has served within the previous two years, or any business with which the commissioner is negotiating for or has an arrangement or understanding concerning prospective partnership or employment. Any actual or potential interest shall be disclosed at the meeting of the commission where the action is being taken.