Benzaldehyde is the simplest and possibly the most industrially useful member of the family of aromatic aldehydes. Benzaldehyde exists in nature, primarily in combined forms such as a glycoside in almond, apricot, cherry, and peach seeds. The characteristic benzaldehyde odor of oil of bitter almond occurs because of trace amounts of free benzaldehyde formed by hydrolysis of the glycoside amygdalin. Benzaldehyde is a versatile intermediate because of its reactive aldehyde hydrogen, its carbonyl group, and the benzene ring. Benzaldehyde is formed from phenylpyruvic acid, derived by the aminotransferase activity on phenylalanine, in the presence of high levels of Mn2+, and contributes to the generation of flavor compound during cheese ripening. Benzaldehyde is a synthetic flavoring substance, sanctioned by the U.S. Food and Drug Administration (FDA) to be generally recognized as safe (GRAS) for foods. Benzaldehyde is also recognized as safe for use as a bee repellant in the harvesting of honey. Benzaldehyde's most important use is in organic synthesis, where it is the raw material utilized to produce various aldehydes. Because Benzaldehyde rapidly metabolizes to Benzoic Acid in the skin, the available dermal irritation and sensitization data demonstrating no adverse reactions to Benzoic Acid were considered supportive of the safety of Benzaldehyde.

Fentanyl is a potent agonist of mu opioid receptor. It is used to relieve severe pain, such as after surgery or during cancer treatment, and breakthrough pain (flare-ups of intense pain despite round-the-clock narcotic treatment). Fentanyl is an extremely powerful analgesic, 50–100-times more potent than morphine. Fentanyl harbors massive risk for addiction and abuse regardless of its prescription form. Fentanyl abuse is especially dangerous to those without a tolerance to opioids. The substance’s already elevated risk of overdose is multiplied when someone without a tolerance abuses it.