More information on what the plastic numbers mean is here: www.babygreenthumb.com/p-122-safe-plastic-numbers-guide.aspx
More specific to CF, many brands of prescription pancreatic enzymes contain phthalates, a class of plasticizers that are known endocrine disruptors and can cause liver damage. I recommend avoiding enzymes containing phthalates, especially those who have liver issues. Pancreaze is a brand that does not contain phthalates. It's an outrage that phthalates are banned for use in toys and baby products, but not in pharmaceuticals! This must change!