Description
A naturally occurring oil in citrus peels and other plants, d-limonene is present in foods and in many essential oils. It can also be synthetically produced. D-limonene is extensively used as a food additive to provide a citrus flavor, as a fragrance in perfumes, air fresheners, and personal care products, and as a natural replacement for petroleum-based solvents in paints and cleaning products. D-limonene may also be used as an inert ingredient in pesticides.
Children may inhale its fumes when these products are used indoors, or they may ingest d-limonene in citrus flavored foods.
Though cited as a cancer-causing substance by some, it is still unclear whether this is true. However, fumes containing d-limonene may irritate the eyes and airways of some people, especially when fumes build up indoors.
Health Effects
Immediate Health Effects
- If SWALLOWED, d-limonene is Moderately Toxic
- If ABSORBED THROUGH SKIN, d-limonene is Not Available
- If INHALED (SNIFFED OR BREATHED IN), d-limonene is Not Available
Longterm or Delayed Health Effects
- This chemical is considered an Unclassifiable Carcinogen by the World Health Organization, the U.S. Environmental Protection Agency, or another agency.
Other
- May be irritating to skin, eye, or airways.
- In laboratory animals, d-limonene has caused kidney tumors in male rats but not in female rats or mice of either gender. The mechanism by which d-limonene caused the tumors in male rats has been determined to be irrelevant to humans, however.
- In laboratory animals exposed to high doses in the womb, d-limonene has delayed growth and caused skeletal abnormalities.
- Limonene can react with ozone, forming particulates that could impact asthmatics and those with other respiratory ailments.
How Exposures Occur
From food
- D-limonene is a natural component of citrus fruits, celery and some spices and as a flavor additive in some foods, beverages and chewing gum. The levels found are usually small quantities.
Inhalation
- Children may breathe fumes when products containing d-limonene, such as citrus-scented air fresheners, perfumes and candles, cleaners and paints, are used indoors, especially without adequate ventilation.
Through the skin
- D-limonene can be absorbed through the skin after application of citrus essential oils, perfumes, soaps and other fragranced personal care products, and through skin contact with citrus-based cleaning
products.
Significant Statistics
In a 1991 test of 31 fragranced perfumes, soaps, and deodorants, limonene was found in over half.
Fisher, Brandy E. “Scents and Sensitivity,” Environmental Health Perspectives, Vol. 106 (December 12, 1998), pp. 106-112.http://ehpnet1.niehs.nih.gov/docs/1998/106-12/focus.html
Humans are estimated to consume 0.1 milligram of d-limonene per kilogram of body weight each day.
Concise International Chemical Assessment Document on Limonene (No. 5). World Health Organization, International Programme on Chemical Safety, 1998.
http://www.who.int/pcs/cicad/summaries/cicad_5.html
Solutions
How to detect d-limonene
- Any citrus-based cleaning product, air freshener, perfume, essential oil or fragrance product is likely to contain d-limonene, particularly those that list oil of orange as an ingredient. For more on fragrances in household products, see Fragrances: What Your Nose Needs to Know.
How to minimize exposure to d-limonene
- Ventilate well when using products that contain d-limonene or those with strong citrus odor. Some children may be bothered by the fumes, so keep them away.
Alternatives
- Use natural deoderizers, such as baking soda, to absorb odors rather than masking them with fragrance-based air fresheners. See How To Freshen Indoor Air Naturally.
- Instead of spraying air fresheners to block odors, improve indoor air quality with good ventilation.
For More information
Books, articles, factsheets and reports
Raloff, Janet. “Lemon-scented Products Spawn Pollutants,” Science News,Vol. 158, No. 24 (December 9, 2000).
Other government agencies
National Toxicology Program
National Institute for Environmental Health Sciences
P.O.Box 12233
Research Triangle Park, NC 27709
919-541-3345
http://ntp-server.niehs.nih.gov/
Nonprofit organizations
Other websites
International Agency for Research on Cancer, World Health Organization
http://www.iarc.fr
Other
Limonene can react with ozone, forming particulates. It is unlikely that levels would rise to levels that might trigger asthma.
In Florida, D-limonene is regulated as an air pollutant when released from citrus processing plants, because it can combine with nitrous oxide to form ozone, contributing to smog, on hot days.
Department of Environmental Protection, Citrus Processors Sign Memorandum of Understanding to Reduce Pollution. State of Florida Department of Environmental Protection.
http://www.dep.state.fl.us
