Orange oil

Orange oil is an essential oil produced by glands inside the rind of an orange fruit. It is extracted or steam distilled as a by-product of orange juice production. It is composed mostly of d-limonene, and is therefore often used in place of pure d-limonene, which can be further extracted from the oil by distillation.

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Limonene

Main article: Limonene

Limonene is what gives citrus fruit their familiar aroma, and is therefore used in perfume and household cleaners for its fragrance. It is also an effective, environmentally friendly, and relatively safe solvent, which makes it an active ingredient of choice in many applications, such as, but not limited to, adhesive and stain removers, cleaners of various sorts, and strippers.

Safety

The limonene which is the main component of the oil is a mild hand irritant, by virtue of dissolving the protective oils in the skin. It is wise to wear solvent-resistant gloves when handling limonene solutions.

Limonene is also combustible. If you squeeze an orange peel in front of a flame, the glands will burst with an aerosol that will ignite on contact with the flame.

Limonene has been observed to cause cancer in male rats, by reacting with α2U-globulin, which is not produced by female rats. There is no evidence for carcinogenicity or genotoxicity in humans. The IARC classifies d-limonene under Class 3: not classifiable as to its carcinogenicity to humans. [1]

For more details of the regulatory status and toxicity, see limonene.

Limonene and its oxidation products are skin irritants, and limonene-1,2-oxide (formed by aerial oxidation) is a known skin sensitizer. Most reported cases of irritation have involved long-term industrial exposure to the pure compound, e.g. during degreasing or the preparation of paints. However a study of patients presenting dermatitis showed that 3% were sensitized to limonene.[4]

Limonene causes renal cancer in male rats, but not in female rats or in mice of either sex, due to binding of the metabolite limonene-1,2-oxide to α2u-globulin, a protein produced only by male rats. There is no evidence for carcinogenicity or genotoxicity in humans. The IARC classifies d-limonene under Class 3: not classifiable as to its carcinogenicity to humans.[4]