"Our ingredients are offered a playlist ranging from soft, classical jazz to heavy metal to best express their individualistic tastes."
Joking aside, this is one where you'll might need to focus on the specific heavy metal risks associated with individual ingredients. If you're the producer of raw here and someone is asking you for it, you'll need to determine what you can prove either via your supply chain or via testing and possibly supplying COA's. If you regularly test for heavy metals, list the ones you test for in a statement and say that the material is checked for those specific ones with COA's available upon request.
If you're the one developing it to use with your suppliers, you should consider which heavy metals are common in your specific ingredients and have the suppliers effectively agree that they're monitoring for heavy metals on their side to give your company confidence in buying from them.
In most cases, I'm having trouble finding an established limit for the presence of certain metals, and FDA is not particularly helpful at the moment. Yes, they have things like the "Closer to Zero" program focusing on lead in children's foods, but it only states fluff like "...reduce dietary exposure to contaminants to as low as possible, while maintaining access to nutritious foods." That's a direct quote: no specified limit, just a generic try-to-do-better which leaves commodities known to contain trace levels of lead (ahem, cinnamon) in a gray area where enforcement can be selectively applied.
