You could also request the composition of the packaging and do your own research on each component. A good supplier should be able to get you everything you need up to and including the scientific data to support the safety of that product.
I sent a request (we're also organic) to a company that would be providing detergent, I received back 20 documents including the research paper that proved their position. That is the kind of support you should be getting.
From the FDA
"You may ask the manufacturer for a letter of guaranty to customers (Section 303©(2) of the act) certifying that a particular product is acceptable for the intended food-contact use." Which is not a letter of comformance
FSAN/Office of Food Additive Safety
Section 303 of the Federal Food, Drug, and Cosmetic Act
Section 303 of the Federal Food, Drug, and Cosmetic Act (the Act) provides penalties for persons who violate certain provisions of the Act. Section 303, paragraph © of the Act states that no person shall be subject to the penalties of subsection (a)(1) for having received, or proffered delivery of, adulterated or misbranded food additives if he has established a good faith guarantee from whom he received the articles. This paragraph was included in the 1958 amendments to the Federal Food, Drug and Cosmetic Act and remains the legal basis for the "letter of guaranty" supplied by many manufacturers to their clients. Title 21 CFR 7.12 Guaranty and Title 21 CFR 7.13Suggested forms of guaranty, provide example language for such a letter of guarantee.