Mo. Rev. Stat. § 293.230: Experienced coal miner to handle explosives or gases.

It shall be unlawful for any operator or agent of a coal mine to employ persons underground whose duties may involve contact with inflammable gases, or the handling of explosives, who have not had experience in such duties, unless all such employees are placed under the immediate charge and control of some competent and experienced miner, so as to secure the safety of other persons employed in the same mine.