List 10 examples of substances that are beneficial in small quantities but poisonous in large doses

Following Ten compounds are benificial in small quantity but poisonous at higher concentration.

                         1) Iron

                         2) Oxygen

                         3) Vitamin A

                         4) Vitamin D

                         5) Table Salt

                         6) Ethanol 

                         7) Amygdalin (found in apple)

                         8) Solanin (found in potato)

                         9) Formaldehyde (found in pears)

                         10) Cucurbitacin E (found in Cucumber)