There could be impurities in your food that can be harmful to your health.
Everyday atta is often soiled with sand and dust. 
Groundnut oil is adulterated with low quality ones like soybean oil, palm olein, cottonseed oil etc. 
Chalk powder and washing soda is often used as a common adulterant in sugar. 
Tur dal is often adulterated with Kesari dal and colored with metanil yellow. 
There's no adulteration, throughout the process of delivering food to you.