105: Camphor and Moth Repellents

INTRODUCTION

Many different products have been used as moth repellents. In the United States, paradichlorobenzene has largely replaced both camphor and naphthalene as the most common active component of moth repellent and moth flakes because of its lower toxicity. However, life threatening camphor and naphthalene toxicity still occurs, especially in immigrant communities, from exposures to imported camphor or naphthalene-containing pro­ducts.^3,49,64,80 Therefore, toxicity of camphor, naphthalene, and paradichlorobenzene should be considered when evaluating possible exposure to moth repellents.

CAMPHOR

History and Epidemiology

Camphor (2-bormanone, 2-camphonone), a cyclic ketone of the terpene group, is an essential oil originally distilled from the bark of the camphor tree, Cinnamomum camphora. Today, camphor is synthesized from the hydrocarbon pinene, a derivative of turpentine oil. Camphor has been used for centuries as an aphrodisiac, contraceptive, abortifacient, suppressor of lactation, analeptic, cardiac stimulant and antiseptic.^{43,55,57,61,72,96,109} Camphor is a commonly used ingredient found in many nonprescription remedies for cold symptoms, cold sores, and in muscle liniments.^{2,75,77,93,97} Camphor is also rarely abused as a stimulant.⁶⁹

Camphorated oil and camphorated spirits contain varying concentrations of camphor. Historically, most camphorated oil was prepared as a 20% weight (of solute) per weight (of solvent) (w/w) solution of camphor with cottonseed oil, and most camphorated spirits contained 10% w/w camphor with isopropyl alcohol. Toxicity and death following ingestion of camphorated oil, which was frequently confused with castor oil and cod liver oil, prompted the FDA to ban the nonprescription sale of camphorated oil in the United States in 1980.^{11,61,76,120,125} The FDA ban of camphorated oil was followed by a restriction on camphor content in 1983, limiting the camphor concentration to less than 11% in nonprescription camphor containing products in the United States.¹²⁶ However, camphorated oil is still used as an herbal remedy and muscle liniment, and products containing greater than 11% camphor can still be purchased in local stores of various ethnic communities in the United States and in other countries.^35,49,64,117

Common camphor-containing products include ointments often used for herpes simplex on the lips (usually <1% camphor), muscle liniments, rubefacients (usually 4%–7% camphor), and camphor spirits (usually 10% camphor). Paregoric, camphorated tincture of opium, contains a combination of anhydrous morphine (0.4 mg/mL), ethanol (46%), and benzoic acid (4 mg/mL) but only a small amount of camphor.⁶⁸ For industrial uses, camphor can be purchased legally in the United States and contains up to 100% camphor. Occupational exposures to camphor occur during the manufacture of plastic, celluloid, lacquer, varnish, explosives, embalming fluids, and numerous pharmaceuticals and cosmetics.⁶⁸

Although products containing lower concentrations of camphor are implicitly safer, life threatening toxicity and death may still result from misuse or intentional overdose. Most reported cases of acute camphor poisoning are unintentional ingestions of camphor containing products mistaken for other medications or therapeutic misadventures from nonprescription products, including home ...