When One Piece began, most fans assumed that it was set in a world with 17th Century technology, but that is not entirely true. There are quite a few scientists in One Piece, and some of them have dabbled in cloning, genetics, virology and cybernetics. These scientific endeavors led to the creation of various scientific weapons that are powerful and highly effective. In the wrong hands, these scientific weapons can cause a lot of damage.
Source：https://www.cbr.com/strongest-scientific-one-piece-weapons/
