The Consumer Product Safety Commission is responsible for the requirements for child safety in packaging in the US. This relates to all products from household chemicals to pharmaceuticals and is specifically defined in the Poison Prevention Packaging Act (PPPA) of 1970. The EPA regulates pesticides and other chemicals that require child resistant packaging. The actual test requirement is specifically defined for child safety (testing children) and senior friendly (testing seniors). The full test can be found by looking up 16. CFR 1700.20 in the Federal Register.
You will not find marijuana listed in the federal regulation for products requiring child resistant packaging. The reason is that marijuana is still federally illegal and the CPSC does not have any involvement. Since the CPSC standard is the only standard used in the US for testing and certifying a package to be child resistant. Most cannabis state regulators defer to this standard in their specific state regulations.