(2) a student-learner who is enrolled in a course of study and training in a cooperative vocational training program under a recognized state or local educational authority, or in a course of study in a substantially similar program conducted by a private school; or

(3) a trainee in an on-the-job training program approved by the commissioner; or

(4) a minor who is employed in the occupation in which he has completed training as a student-learner as provided in subparagraph (2) of this subdivision or as a trainee as provided in subparagraph (3) of this subdivision; or

(5) a minor who is employed in the occupation in which he has completed a work training program of a non-profit organization or a training program which is publicly funded in whole or in part, and as part of such program received safety instruction and training in the use of machinery, provided that such safety program has been approved by the commissioner. As used in this paragraph the term "non-profit organization" means an organization operated exclusively for religious, charitable, or educational purposes, no part of the net earnings of which inures to the benefit of any private shareholder or individual. b. An employment certificate required by subdivision two of section one hundred thirty-two of this article shall for the purposes of section fourteen-a of the workmen's compensation law be deemed to authorize employment under subparagraphs (3), (4) and (5) of this subdivision. 4. In addition to the cases provided for in this section, the commissioner, when it is found upon investigation that any particular trade, process of manufacture, occupation, or method of carrying on the same, is dangerous or injurious to the health of minors, may adopt rules prohibiting or regulating the employment of such minors therein. In addition to the adoption of such rules, the commissioner may also adopt such other rules and regulations as are determined necessary to carry out the purposes of this section. 5. In addition to the rulemaking authority set forth in subdivision four of this section, when it is found upon investigation that employment on a farm is dangerous or injurious to the health of minors, the commissioner may adopt rules prohibiting or regulating the employment of such minors therein, which rules shall be in accordance with and consistent with those promulgated by the United States secretary of labor in this regard.