A-pinene is an active component found in juniper berries and used in artificial lemon and nutmeg flavoring. The component is found in many other natural sources, such as black pepper, orange leaves, cumin, fennel. It is the main ingredient in turpentine and although considered safe for human consumption, it does act as a local irritant and is deadly at 180 mg.
Myrcene is a pleasant-smelling agent also found in orange peel and hop oil, in addition to juniper berries. Myrcene has no known toxicity to humans. It is most commonly used as a flavoring agent for root beer, candy and baked goods.
Sabinene is responsible for the woody, aromatic piney smell of the juniper berries. This colorless component has no known toxicities to humans. You can find the same substance in many natural sources such as cypress, fennel, ginger and grapefruit oil.
Caryophyllene is the most widely distributed sesquiterpene, (an organic compound that acts as biosynthetic building block) in nature. This dissolves in alcohol and is a natural constituent of the oils in cloves and rosemary. Some of the primary uses are in the perfume industry where caryophyllene lends a woody, spicy aroma to products. According to Academia.edu, clinical studies have shown it to be potentially effective as an antibiotic, anesthetic, and anti-inflammatory agent.