Limonene

General information

Since the 1980s limonene has been used as an alternative to traditional solvents and degreasing agents. It is a monoterpene found in a variety of fruits, vegetables, herbs, trees, and bushes. Limonene constitutes the main volatile component of some citrus oils and represents a small fraction of the terpenes in pine needle oils and turpentine. Biogenic and anthropogenic sources release large amounts of limonene into the atmosphere, and biogenic emissions may meet or exceed anthropogenic sources [ ].

Limonene is used as a substitute for chlorinated hydrocarbons, chlorofluorocarbons, and other solvents. In concentrations of 30–100%, it is used as a metal degreaser before painting, as a paint solvent, and as a cleaner in the printing and electronic industries. It is also used in numerous other products, such as home cleaning products, disinfectants, industrial hand cleansers, odorants, rubber, wax and paint strippers, adhesives, lubricating oils, essential oils, cosmetics, fire extinguishers, and wetting and dispersing agents. For more than 50 years, it has been used as a fragrance and flavoring additive to perfumes, soaps, food, and beverages.

Its medicinal uses include chemopreventive and chemotherapeutic properties [ , ]. It has also been used to dissolve gallstones by administration through a choledochal drain [ , ] and to relieve heartburn and gastroesophageal reflux [ ].

Although data are limited, limonene, linoleic acid, and oleic acid are probably of low toxicity. Human dietary and in vitro studies of linoleic and oleic acids have shown alterations in erythrocyte membranes, platelet activity, sperm motility, and thyroxine binding; however, these findings have not been extended to potential hazards in exposed workers. Until more data are available, conclusions regarding occupational health effects remain difficult to determine.

Human exposure to these products is common and almost certainly occurs during daily food intake. Medical management of exposure is symptomatic and supportive. Mild skin irritation can occur, and oxidative products of limonene can produce skin sensitization. Patients with skin or ocular exposure should be decontaminated with water or saline respectively. Treatment of dermal effects involves removal and symptomatic skin care, such as antihistamines for allergic effects. An ophthalmologist should see patients with ocular complaints that do not resolve with irrigation or who have abnormal ocular findings on examination [ ].