No child shall be employed pursuant to a work-training certificate as provided in § 40.1-88 where such employment requires such child to work in any occupation which is deemed hazardous under § 40.1-100 A or regulations promulgated thereunder. However, a child sixteen or seventeen years of age may be employed in certain such occupations as part of a work-training program in accordance with rules and regulations promulgated by the Commissioner. No child shall work in a work-training program except pursuant to a written agreement which shall provide: (1) that the work of such child shall be incidental to his training, shall be intermittent and for short periods of time and shall be under the direct and close supervision of a competent and experienced person; (2) that safety instruction shall be given by the school and correlated with on-the-job training given by the employer; and (3) that a schedule of organized and progressive work processes to be performed shall have been prepared. Such written agreement shall set forth the name of the child so employed and shall be signed by the employer and the coordinator of schools having jurisdiction. Copies of such agreement shall be retained by the school and the employer, and a copy thereof shall be filed with the Department. Any such work-training certificate or written agreement may be revoked at any time that it shall appear that reasonable precautions for the safety of such child have not been observed.