Citronella oil

Citronella oil is classified in trade into two chemotypes:[7]

Ceylon type

• CAS: 89998-15-2
• CAS: 8000-29-1
• EINECS: 289-753-6
• FEMA: 2308
• CoE: 39
• Obtained from: Cymbopogon nardus Rendle
• Main components: citronellal (5–15%), geraniol (18–20%) and geranyl acetate (2%), citronellol (6–8%), limonene (9–11%), and methyl isoeugenol (7–11%).

The major constituents of the Java type citronella oil

Direct application of citronella oil has been found to raise the heart rate of some people.[10] Health Canada banned the oil's use as an insect repellent in 2012 but later lifted the ban in February 2015.[11]

At present, the world annual production of citronella oil is approximately 4,000 tonnes. The main producers are China and Indonesia - producing 40 percent of the world's supply. The oil is also produced in Taiwan, Guatemala, Honduras, Brazil, Sri Lanka, India, Argentina, Ecuador, Jamaica, Madagascar, Mexico, and South Africa.

The market for natural citronella oil has been eroded by chemicals synthesised from turpentine derived from conifers. However, natural citronella oil and its derivatives are preferred by the perfume industry.[12]

Video tracking of a stable fly, demonstrating repellency of citronella oil [13]

A bottle of citronella oil for Mosquito repellent

Citronella oil is popular as a natural insect repellent. Its mosquito repellent qualities have been verified by research,[14] including effectiveness in repelling Aedes aegypti (dengue fever mosquito).[15] To be continually effective, most citronella repellent formulas need to be reapplied to the skin every 30–60 minutes.[16]

Citronella candles (which burn citronella oil) are no more effective than other candles at repelling insects, and experts do not recommend it as a useful method.[17] [18]

Research also indicates that citronella oil is an effective repellent for body lice, head lice, and stable flies.[13][19][20] A study conducted by DARPA in 1963 determined that hydroxycitronellal was an effective repellent against both aquatic and terrestrial leeches.[21]

The US Environmental Protection Agency states that citronella oil has little or no toxicity when used as a topical insect repellent, with no reports of adverse effects of concern over a 60-year period.[22] Some products are applied to human skin, so EPA requires proper precautionary labeling to help assure safe use. If used according to label instructions in the US, citronella is not expected to pose health risks to people, including children and other sensitive populations.[2] The US Food & Drug Administration considers citronella oil as generally recognized as safe (GRAS).

Canadian regulatory concerns with citronella as an insect repellent are primarily based on data-gaps in toxicology, not on incidents.[23][24]

In the EU, Ceylon type citronella oil is placed on the category 3 list, with some safety concern regarding methyl eugenol.[7] In the UK, EU legislation governing insect repellents came into force in September 2006, which banned citronella as an active ingredient in any insect repellent products.[25] This applied to insect repellent for both humans and other animals. It can still be sold as a perfume, but must not be sold as an insect repellent.