Can lavendar, basil, and peppermint essential oils repel insects?

As a mother of three and a toxic exposures expert, I've been wondering about insect repellents. During our family's spring break vacation, we visited a high-risk area for the Zika virus.

While pregnant women and women of childbearing age are of greatest risk to the Zika virus, Zika can make anyone sick for up to a week with fever, rash, joint pain, red eyes, and other symptoms. The effects of Zika are still being studied so I was also nervous about the unknown, and potential risks, to my children getting infected. The World Health Organization declaring it a "Public Health Emergency of International Concern" also motivated me to be extra cautious. 

So, I researched for the least toxic insect repellants that were still considered effective against Zika. I've read and seen products that claim that essential oils from basil, lavendar, peppermint, and other plants can repel insects. If this was true, what saviors!

I ended my research more informed but still conflicted. But I will now use both sets of options (chemical and natural) as strategies against dangerous insect bites. When I use each depends on the risks involved.

What is the concern with traditional bug repellents? 

The most popular key ingredient in conventional bug spray is DEET (N,N-diethyl-meta-toluamide). Some DEET-based products have been found to be the most effective and long-lasting (up to 8 hours of performance) in studies. However, DEET, a registered pesticide, poses risks to you too.

DEET can be absorbed into your bloodstream, and even into your gut. One major concern about the health effects of DEET is how it affects some people's central nervous systems. Dr Mohamed Abou-Donia of Duke University found that DEET killed brain cells and led to behavioral changes in rats after frequent and prolonged use.

In the United States, DEET is available in approximately 120 products that are currently registered with the EPA, ranging in concentration from 5 to 99% DEET. And the EPA says it's safe to use as directed. However, some authorities are more cautious. For example, Health Canada phased out insect repellents with concentrations of DEET above 30% by December of 2004. (Click here for precautions by Health Canada: DEET precautions). 

In 2005, two healthier alternatives to DEET—picaridin and oil of lemon eucalyptus—were approved by the U.S. Centers for Disease Control (CDC) for protection against mosquitoes. Picaridin has been long-used to repel mosquitoes in other parts of the world. Oil of lemon eucalyptus is derived from eucalyptus leaves and is the only plant-based active ingredient for insect repellents approved by the CDC.

Are natural formulas with pure essential oils effective? 

Even more natural insect repellents are made of organic botanical butters (like shea butter) and pure essential oils that include lavendar, peppermint, basil, lemon eucalyptus, cedar, citronella, geraniol, lemongrass, and rosemary. However, how effective they are is questionable. Consumer Reports found that the products it tested that were made with natural plant oils (including cedar, cinnamon, citronella, clove, geranium, lemongrass, rosemary, or peppermint) did not perform well: effectiveness did not last for more than 1 hour against Aedes mosquitoes, and some failed almost immediately.

What do I choose for my family?

Personally, when my children are in low-risk areas (like our backyard), I use insect repellents that use essential oils to deter mosquito bites. These essential oils include citronella, lavendar, basil, lemongrass, clove, rosemary, geranium, and peppermint. It helps us when we are in our yard, and we know to reapply often. In our backyard though, the risks from mosquito bites are not high, just the annoyance and discomfort from itchy skin.

However, when we travel to areas that pose higher risks (e.g., Lyme Disease, Zika virus, West Nile Virus, or malaria), then I more seriously consider insect repellents with picaridin (The same Consumer Reports' study on insect repellents mentioned above found the best performing product contained 20 percent picaridin), or oil of lemon eucalyptus (containing 30 percent oil of lemon eucalyptus). I would even consider DEET. 

Like most things, the most nontoxic and effective solutions depends on the risks involved. If using more conventional insect repellents, I would follow the precautions below.

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Decisions when selecting conventional insect repellents:

1. Assess the risks involved. For example, if you're selecting insect repellents where risks include a potentially life-altering consequence, like Lyme Disease or the Zika virus, then consider a more proven insect repellent. If the risks are just annoying itchy skin and you're applying the repellent on young children, then natural products with pure essential oils may be sufficient.
2. If you're looking for something more effective than essential oils, then good active ingredients to choose from include: DEET, picaridin, or oil of lemon eucalyptus. Consumer Reports found that products with picaridin and DEET as key ingredients generally performed well.
3. Consider the percentage used of the key ingredients listed above. For example, Consumer Reports found that what generally worked well for preventing the mosquitoes from biting for about 8 hours contained 20 percent picaridin, and 25 percent deet. If using DEET, Consumer Reports and Health Canada recommend avoiding mosquito repellents with more than 30 percent DEET (Consumer Reports found that insect repellents with 15 to 30 percent DEET provided long-lasting protection against mosquitoes and ticks), and do not use it at all on infants younger than 2 months. 

In addition, please follow other strategies below.

Other strategies

The CDC emphasizes that avoiding mosquito bites requires multiple strategies. Below are additional strategies to reduce the risks from chemical insect repellents and disease-carrying insects.

• Minimize the amount of product you need to apply. For example, cover more of your body with long sleeves and long pants to reduce how much insect repellent you need to apply on your skin. 
  • Apply repellent to clothing rather than skin to reduce exposure.
  • Remember that heavy doses don’t work better. 
• Don't put insect repellent on skin that's under clothing. Apply repellents only to exposed skin or clothing.
• Don’t apply mosquito repellents to vulnerable skin, like over cuts, wounds, irritated skin, or immediately after shaving. Consider covering these areas with a bandaid to protect from both insect repellants and insects.
• When applying to your face, spray first on your hands, then rub in, avoiding your eyes and mouth, and using sparingly around ears.
• Don’t let young children apply. Instead, put it on your own hands, then rub it on. Limit use on children’s hands, because they often put their hands in their eyes and mouths.
• Don’t use near food, and wash hands after application and before eating or drinking.
• At the end of the day, wash treated skin with soap and water, and wash treated clothing in a separate wash before wearing again. Repellent-treated clothes should stay outside living areas to reduce exposure.
• Do not spray in enclosed areas.
• Avoid two in one products that combine sunscreen and DEET. Re-applying sunscreen frequently, as you should, may expose you to unnecessary amounts of DEET.
• DEET repellents should not be inhaled. 
• Plant mosquito repelling plants like lemon balm, catnip, basil and lemon geraniums around outdoor sitting areas and encouraging mosquito predators like bats and dragonflies can help reduce mosquito populations.
• Avoid combining insect repellent with medications and other sprays. The combination could create an unhealthy cocktail effect.
• Read and follow manufacturer's directions. 
• Stay updated. New data from studies or developments among affected populations are always enlightening us. I check for opinions by the EPA, the World Health Organization, and other countries, like Health Canada.

Have you been successful with nontoxic pest management?

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