Consider the following statements about crude drug adulteration:

1. Substitution with a cheaper plant is a form of adulteration.
2. Deliberate addition of foreign matter is known as intentional adulteration.
3. Using exhausted drugs is a type of sophisticated adulteration.
4. Adulteration is always accidental and never intentional.
5. Adulteration affects drug efficacy and safety.

Which statements are correct?