For the US market, products must comply with the Flammable Fabrics Act (16 CFR Part 1610); ensure the supplier provides a General Certificate of Conformity (GCC). For the EU, adherence to REACH regulations is critical to ensure the absence of harmful Azo dyes, phthalates, and lead. If the costume includes electronic components (e.g., LED lights), it must carry the CE mark and RoHS certification. Always request OEKO-TEX Standard 100 certification to guarantee the textiles are free from toxic substances.