What's the risk? – Repelling ticks & mosquitos

This new series looks at common products and ingredients we use throughout the spring and summer to explore their safety and toxicity. This first post will look at ingredients to help repel ticks and mosquitos.

What do I need to know?

Every year, we see variations in tick and mosquito population size depending, in part, on the duration and temperatures experienced throughout the winter months. 
In general, warmer, shorter winters mean more insects, including potential disease-carrying ticks and mosquitos, survive and reemerge in the spring and summer months. We can expect to see more people impacted by these diseases when more potential disease-carrying insects thrive. 

What are common diseases carried by ticks and mosquitos? 

Ticks and mosquitos can carry diseases that are severe. This post will look at the diseases most frequently found in North America (1,2). 
Tick-borne diseases found in North America

  • Anaplasmosis
  • Babesiosis
  • Colorado tick fever
  • Ehrlichiosis
  • Lyme disease
  • Powassan encephalitis
  • Q fever
  • Rocky Mountain Spotted Fever
  • Southern Tick-Associated Rash Illness
  • Tick-Borne Relapsing Fever
  • Tularemia 

Mosquito-borne diseases found in North America 

  • Eastern Equine Encephalitis 
  • Jamestown Canyon Virus 
  • La Crosse Encephalitis 
  • St. Louis Encephalitis 
  • West Nile Virus 
  • Western Equine Encephalitis 
  • Zika

What happens if I contract a disease from a tick or mosquito? 

Like most diseases, each person reacts differently to different pathogens. Typically, people with underlying health conditions as well as those that are pregnant, very young, and elderly experience more severe illnesses. If you suspect that you've contracted an insect-borne disease, it's important to seek medical care from a licensed physician, as treatment will vary depending on the illness and severity.  

What can I do to prevent bites from ticks and mosquitos? 

You can use an Environmental Protection Agency (EPA) registered insect repellent and wear long pants and shirts in wooded areas or areas with many insects.  

Do all insect repellents work?  

There are two kinds of insect repellents:

  • EPA-registered products that have been tested for efficacy and safety.
  • Unregistered products that have been tested only for safety

EPA-registered products are tested to ensure they repel mosquitoes and/ or ticks and are safe when used as directed. The EPA recommends using these products when you're trying to avoid disease-carrying insects.

Unregistered products are tested to ensure safety, meaning if someone uses the products, including vulnerable populations like children and pregnant women, the product is unlikely to cause harm. Unregistered products are not tested to ensure efficacy (1,2). This means that unregistered products may be safe for human use, but they also may not repel insects, such as mosquitos and ticks.

What are Common EPA-registered insect repellent ingredients?  

Common EPA-registered active ingredients include:

  • 2-undecanone
  • Catnip oil
  • DEET
  • IR-3535
  • Oil of Citronella
  • Oil of Lemon Eucalyptus
  • Picaridin
  • q-Methane-3,8-diol (pmd)

The most commonly used ingredient in EPA-approved insect repellents is DEET, and we find it in more than 500 products.

Learn more: https://go.msu.edu/Ncp

Is DEET toxic? 

Anything can be toxic in a high enough dose and at a frequent dose-rate, even water (1,2)!

That said, the U.S. Centers for Disease Control and Prevention (CDC) recommends using DEET products because extensive research shows that DEET is safe and highly effective at preventing mosquito and tick bites. It's also the most commonly used EPA-registered ingredient in insect repellent products (1,2,3,4,5).

Using safe and effective DEET containing insect repellent products helps prevent the spread of harmful insect-borne diseases like malaria, Zika, West Nile, Lyme Disease, and more. These diseases can cause severe illness, and the potential for contracting these diseases decreases with proper preventative measures, including using insect repellent (1,2).

Learn more: https://go.msu.edu/Bhp

Is DEET safe to use? Even for children and pregnant and nursing mothers? 

When used according to the directions, DEET is safe and even recommended for use by all populations who may be exposed to potentially disease-carrying mosquitos and ticks (1,2,3).

The EPA's data shows it's safe for all children regardless of age. However, the American Academy of Pediatrics (AAP) recommends using DEET-containing products only on children older than two months of age (1,2).

We should never apply DEET-containing products directly to children's hands or faces. Additionally, the AAP recommends that children wash off the DEET after it's no longer needed (1,2).

Again, when used as directed, DEET-containing products are safe for pregnant and nursing mothers (1).

Are botanical-based insect repellents safer? 

Again, anything can be toxic in high enough doses and at a frequent dose-rate. 

EPA-registered botanical-based insect repellents will have a safety profile and directions that outline their safe and effective use. It's essential to follow all listed directions on the product to ensure you're using them safely. If you are not using the products as directed, you can experience adverse side effects. 

EPA-registered botanical-based insect repellents will have an EPA registration number on the product, and you can look up on the EPA website to confirm. 

Not all botanical-based products are tested for efficacy. Only those registered with the EPA will be tested for effectiveness and safety.  

Can insect repellents cause adverse reactions? 

Although rare, insect repellent products can cause some people to have skin irritation or reactions regardless of the active ingredient. In that case, you should wash the area to remove any product, discontinue use, and contact a medical professional if it is severe (1).

What's the risk? 

Each person has a risk threshold, representing the level of risk we feel comfortable taking in a specific situation based on the potential outcomes.

We know the risk of an adverse side-effect from an insect repellent product is low if we use the product according to the directions.

We know that the potential outcome of being infected with a disease from a disease-carrying insect can be quite severe.

We know that our specific situation will change how exposed we are to insects. For example, camping in the woods will expose us to more ticks and mosquitos than walking around a paved neighborhood or downtown area.

While we cannot know your risk threshold, using the available information, it makes sense to use insect repellent when exposed to more potentially disease-carrying insects.

The good news.  

Many safe and effective products are on the market to help prevent tick and mosquito bites. Knowing the risk for adverse outcomes from using these products is low, we can feel comfortable using them when we think the situation warrants extra insect protection.

If you have any questions about foods and ingredients, please reach out to us on Twitter, send us an email, or submit your idea to us at go.msu.edu/cris-idea

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