Anyone can sell Dangerous goods (AKA Hazmat Goods) but you need to be approved to store your Hazmat goods in a special part of the Amazon FBA Warehouse system.
Amazon considers many products to be hazmat that you might not initially think of (like air fresheners and perfumes which can be highly flammable).
To apply for Hazardous goods storage, go to https://sellercentral.amazon.com/gp/help/201003400 then scroll down to Enroll In The Dangerous Goods Program.
After choosing "FBA Dangerous Good Program", you will click "Next", and then can Apply on the next page.
Approval for the Hazmat / Dangerous Good program can take a few days or a few months based on how many applicants Amazon is reviewing when you apply and your Seller Account history.