Are any First Aid Only items considered hazardous?

No currently produced items from First Aid Only are considered to be hazardous.

Older models of cold packs contained a formula that was considered hazardous in large quantities.

To verify if your older cold pack was apart of this old makeup, please refer to the ingredients list on the cold pack. If the ingredients listed are "water" and "urea" than it is a non hazardous item. If the ingredients vary from these two components, than the cold pack is considered hazardous in large quantities.