Answer:
Because people just do that for no reason
Explanation:
Every 6 months it's recommended to have doctor and dental check-ups.
Yes it does the chemicals in whatever you are smoking are more than likely altered from what it originally was, therefore the chemicals start to taint the blood vessels and damage them permanently.
FDA: they jurisdiction over 80% of the food supply including seafood, dairy and produce.
USDA: they regulate meat, poultry and processed egg products.