Safety Note
Some natural essences have been known to cause allergic reactions when applied directly to the skin. Others have provoked adverse reactions when used in very large quantities, ingested orally, or rubbed into the skin. Even though natural essences in perfumery are diluted in alcohol or other carriers, if you are prone to allergies or have sensitive skin, it may be advisable to try a patch test to see if a given oil is problematic for you. Apply one drop of the oil in question to the inside of your forearm and cover it with an adhesive strip. After a few hours, check for redness or irritation.
I have read that citrus oils in the bath can cause irritation to the skin, but I have included them in many bath blends with no ill result. If your skin is sensitive, however, you may want to put a few drops of a citrus essence in a basin of warm water, then soak your hand and lower arm in it and check for signs of irritation.
It is best to avoid natural essences on the skin during pregnancy. They can pass from the skin into the bloodstream, and some of them may cross the placental barrier. As Christine Wildwood observes in The Encyclopedia of Aromatherapy, "There is no evidence to suggest that unborn babies have been harmed as a result of their mothers using therapeutic applications of essential oils . . . Nevertheless, a number of oils stimulate menstruation and are therefore potentially hazardous, especially during the first three months of pregnancy, when miscarriage is more of a threat." The International Fragrance Association (IFRA) has compiled a list of recommended guidelines for commercial perfumers, which is updated periodically. You can find it on the Web at www.ifraorg.org/guidelines.asp