d-Limonene: Is It A Safe, Effective Alternative to Xylene?

Abstract

d-Limonene (C₁₀H₁₆) is a hydrocarbon of the monoterpene sub-group and is the major constituent of citrus peel oils (90–95%) and other ethereal oils. Used in the food and cosmetic industry for many years, it has been generally regarded as safe. In recent years, d-limonene-based products have been used in some pathology laboratories as a replacement for xylene, a known toxic substance. d-Limonene is readily absorbed into the body, metabolized, and cleared from the body. It appears to perform adequately as a wax solvent and clearing agent, and it has a reduced fire risk compared with xylene.

Although product safety data sheets mention several adverse effects of exposure to d-limonene, exposure to 76 ppm for 2 hr had no irritative or central nervous system effects in volunteers. Headaches and nausea have been reported from some laboratories that have used d-limonene, and proper ventilation is required. Some users have reported skin irritations as well. It does induce renal pathology in some strains of adult male rats but has no proven genetic effects. In comparison, xylene has toxic effects on many organ systems, although it, too, does not appear to be mutagenic or carcinogenic.

d-Limonene appears to be a safe and effective replacement for xylene, although more extensive use and further experimental studies may require revision of this conclusion. ( The J Histotechnol 18:131, 1995)

Keywords:

• clearing agent
• d-limonene
• toxicity
• xylene