Why is adulteration considered harmful for human health?

Why is adulteration considered harmful for human health? State any two points in this regard.

Adulteration usually refers to mixing other matter of inferior and sometimes harmful quality with food or drink intended to be sold. As a result of adulteration, food or drink becomes impure and unfit for human consumption. We can understand this with the following points.
(i) Colouring dyes, calcium carbide, urea, brunt engine oil and even some permitted preservatives are used in excessive amount that affect multiple organs of human body.
(ii) For example, sellers usesome adulterants in the following food articles which lead to harmful effects on human health.