In an effort to avoid bug bites and insect-borne diseases like Zika, West Nile, Keystone virus and Lyme disease, you may automatically turn to products containing DEET, which is known to be the most effective insect repellent on the market. Although the synthetic compound’s been in use for more than 40 years, researchers point out that it may pose some harmful side effects.
It’s true that products containing DEET are widely available. Maybe DEET is even your family’s first line of defense for avoiding bug bites. And it makes sense, given that insect-borne diseases continue to rise in the United States. According to the U.S. Centers for Disease Control and Prevention, illnesses from mosquito, tick and flea bites have tripled in the U.S. — with more than 640,000 reported cases between 2004 to 2016. (1)
A 2018 study published in Clinical Infectious Diseases sought to determine recent patterns for pediatric Lyme disease in western Pennsylvania. After analyzing the electronic medical records of all patients with a Lyme disease diagnosis between the years 2003 and 2013, Children’s Hospital of Pittsburgh (CHP) researchers found that 773 patients met the CDC’s case definition for Lyme disease. The research highlighted the exponential increase in Lyme disease cases in Pennsylvania kids. The data also shows that the disease is migrating from rural to non-rural zip codes, too.
Study author Andrew Nowalk, MD, PhD, an infectious diseases specialist at the Division of Infectious Diseases at the CHP, indicates that Lyme cases at the children’s hospital increased 50-fold from 2003 to 2013. The current models point to the early detection of an epidemic. (2)
The spread of vector-borne diseases is certainly one of the health effects of climate change, and the data is scary. It’s clear we need to be cautious when it comes to protecting ourselves and our children from insect-borne diseases. And it’s more important than ever to take a closer look at our bug repellent product choices.
Although DEET is known as the most effective insect repellent, research shows that it may trigger toxic side effects in some situations. And with more than 500 products containing DEET on the market — with different concentrations and ingredients — choosing the safest repellent for you and your children can be confusing.
Environmental Working Group identifies DEET (in concentrations less than 30 percent) as one of its top picks to reduce the risk of life-altering disease from tick and mosquito bites with low toxicity concerns. But the organization stresses that precaution and proper application is essential. It also IDs science-backed DEET-free options. (More on that later.)
So before you spray on that conventional and possibly problematic bug repellent, consider using more natural alternatives instead. (And if you’re sticking with DEET, please know, at the very least, how to apply it properly.)
Dangers of DEET
According to research published in The New England Journal of Medicine, most cases of serious side effects caused by DEET involve long-term, heavy, frequent or whole-body application of the repellent. When it’s applied with common sense and only on exposed skin for short periods of time, many researchers believe that DEET can be used as an effective and safe way to avoid insect-borne diseases. Still, people today aren’t just dealing with DEET, but rather a toxic body burden threat that includes exposure to dozens, if not hundreds, of different chemicals on a daily basis.
In some cases, DEET alone may cause minor to serious reactions and conditions, including the following concerns: (3)
1. Allergic Reactions
For some people, when DEET is applied to the skin, especially for an extended period of time, it can cause adverse reactions like redness, rash, swelling and hives.
Case studies suggest that some people may be at risk of allergic reactions and even anaphylaxis from exposure to DEET. One case involved a 53-year-old female bridge inspector who experienced severe itching of the skin (called pruritus) and erythema, which involves skin redness, fever and blistering, after an insect repellent containing DEET was applied topically. The next time she used a product containing DEET, she developed hives and swollen eyes. She called 911 and was given a Benadryl injection. (4)
Nova Southwestern University in Florida published another case study describing a 22-year-old man who developed hives immediately after applying insect repellent and coming into contact with others who had used DEET-containing repellents. (5)
And according to reports made to the American Association of Poison Control Centers, symptoms associated with exposure to DEET are related to the route of exposure, with the highest rates caused by exposure to the eyes, followed by inhalation, skin exposure and ingestion. Although 70 percent of the cases reported to poison control (between the years 1993 and 1997) did not develop symptoms, some individuals did experience major side effects and needed medical treatment, including two deaths following skin exposure. (6)
2. Seizures and Brain Malfunction
In some cases, ingestion of DEET can lead to seizures. There are also reports of DEET-induced seizures in children. According to a case analysis published in Human and Experimental Toxicology, clinical reports of children under 16 years old who suffered from brain damage indicate that symptoms can be caused by not only the ingestion of DEET, and repeated and extensive application, but also brief exposure to the insect repellent. The most prominent symptom among the reported cases was seizures, which affected 72 percent of the patients and was significantly more frequent when DEET products were applied to the skin. Researchers concluded that “repellents containing DEET are not safe when applied to children’s skin and should be avoided in children.” (7)
3. Gulf War Syndrome
Gulf war syndrome is a condition that affects veterans of the Gulf War and causes chronic headaches, fatigue, respiratory disorders and skin conditions. Researchers at Duke University Medical Center found that the emergence of these symptoms may be linked to the simultaneous exposure to multiple agents that were used to protect the health of service personnel, particularly DEET, the anti-nerve agent pyridostigmine bromide and the insecticide permethrin.
When the toxic effects of these agents were tested on hens, researchers found that when they were used in combinations, they produced greater neurotoxicity than that caused by individual agents. This may be because the anti-nerve agent can “pump” more DEET into the central nervous system, causing neuropathological lesions and nerve damage. (8)
Although this condition specifically affects those who served in the Gulf war, it may indicate a concern for anyone who is exposed to certain chemical mixtures that include DEET.
4. Carcinogenic Properties
Although studies indicate mixed results, there is some evidence that DEET contains carcinogenic properties that can produce dangerous effects when inhaled or applied to the skin. Scientists in Germany investigated the genotoxic effects of three widely used pesticides, including DEET. When cells from tissue biopsies were exposure to DEET for 60 minutes, the pesticide displayed potential carcinogenic effects in human nasal mucosal cells. (9)
And according to a case study published in the Journal of Occupational and Environmental Medicine, exposure to DEET, herbicides and rubber gloves, which are recommended for use by farmers when they are mixing or applying pesticides, increase the odds of developing non-Hodgkin’s lymphoma, a group of cancers that develop in the white blood cells. (10)
5. Toxic for Pets
The ASPCA Animal Poison Control Center reports that when pets are exposed to DEET-containing products, it can cause significant clinical side effects. If DEET is sprayed in a pet’s eyes, it can cause issues like conjunctivitis, scleritis, corneal ulceration and blepharospasm. If this happens, you need to flush it out of your pet’s eyes for at least 15 minutes.
If your pet inhales DEET, this can cause airway inflammation and difficulty breathing. General exposure to DEET may also cause gastrointestinal issues or side effects including disorientation, shaking, vomiting, tremors and seizures. (11)
6. Environmental Impact
The U.S. Environmental Protection Agency says DEET may be slightly toxic to birds, fish and aquatic invertebrates. When testing DEET on freshwater fish and insects, it was toxic at extremely high levels.
According to the National Pesticide Information Center, DEET is detected in wastewater and in places where wastewater moves into other bodies of water. Even low concentrations produce a slight toxicity in coldwater fish.
When sprayed, DEET remains in the air as a mist or vapor and must be broken down by the atmosphere. The time it takes to break down depends on the temperature, humidity and wind. DEET can also enter the environment through soil, where it’s said to be moderately mobile. (12, 13)
If you choose to use DEET as your go-to insect repellent, there are a few precautions that you can take to avoid potential side effects or adverse reactions. According to the CDC, make sure to follow these directions when using DEET-containing products: (14)
- Do not apply to irritated skin, cuts or wounds
- Do not apply to hands, or close to eyes and mouth
- Do not use on young children
- Do not use under clothing
- Only apply to exposed skin (and minimize exposed skin by wearing long sleeves and pants)
- Do not over apply
- Wash product from your skin with soap and water after use
- Wash clothes that have come into contact with DEET before wearing it again
Better DEET Alternatives
Insect repellents that line the shelves of your local grocery and drug stores can be divided into two categories — those made with synthetic chemicals and those made with plant-derived essential oils and ingredients. Because many consumers are reluctant to apply DEET to their skin, in fear of developing an allergic reaction or even more serious side effects, natural or possibly safer alternatives have become readily available. Here’s a breakdown of some of the best alternatives to DEET:
1. Oil of Lemon Eucalyptus: Oil of lemon eucalyptus is the only plant-based active ingredient for bug repellents that’s approved by the CDC. Studies show that it has protective effects against mosquitos and ticks, and Consumer Reports testing confirms this. (15)
In other research, when insect repellents containing eucalyptus oil were tested on five subjects exposed to mosquitos, they provided a range of protection from 60 to 217 minutes. (16)
Oil of lemon eucalyptus oil should not be used on young children. Before using it on your skin, perform a patch test on a small area of skin to be sure that it doesn’t cause any adverse reactions.
2. Citronella Oil: Scientific evidence suggests that citronella oil is an effective alternative repellent against mosquitos and has a protection time of about two hours. The EPA has categorized citronella oil as an insect repellent due to its high efficacy, low toxicity and customer satisfaction, but it may not be as effective in higher temperatures. (17, 18)
And when citronella oil was tested for its protective effects against mosquito-borne diseases in rural areas of Nepal, researchers found that it “can be employed as an easily-available, affordable and effective alternative mosquito repellent.” (19)
3. Picaridin: Picaridin is a synthetic compound that resembles the natural compound piperine, a compound found in the group of plants that produce black pepper. It’s used on human skin to repel mosquitoes, ticks, fleas, biting flies and chiggers.
Some studies show that individuals who develop allergic reactions to DEET-containing bug repellents may not have the same reaction to solutions containing picaridin, making it an acceptable alternative for those who have a sensitivity to DEET. (20)
When researchers evaluated the safety of picaridin during community mass use for malaria control in rural Cambodia, they found that adverse reactions and abuse were uncommon and generally mild, which supports the safety of picaridin-containing products in the avoidance of mosquito diseases. (21)
4. Geraniol: Geraniol is an extracted oil that comes from plants such as geraniums and lemongrass. It is known for its ability to repel mosquitos and ticks.
Research published in the Journal of Vector Ecology suggests that geraniol may have significantly more repellent activity than citronella in both indoor and outdoor settings, although both natural substances repelled significantly more mosquitos than the unprotected controls. Researchers found that when used indoors, the repellency of geraniol candles was 50 percent, while the geraniol diffusers repelled mosquitos by 97 percent. Outdoors, the repellency rate for geraniol was 75 percent. (22)
And a study conducted in Morocco found that when 1 percent geraniol spray was used on cows to prevent ticks, it showed a reduction of the average number of ticks per animal. (23)
5. Soybean Oil: Soybean oil is an active ingredient in some natural insect repellents used to protect humans against mosquitos.
When researchers at the University of Florida compared the efficacy of insect repellents against mosquito bites, they found that the only natural solution that came close to matching the efficacy of DEET was a soybean-oil based repellent, which provided protection against mosquito bites for 95 minutes. (24)
- Although DEET is known as the most effective insect repellent, research shows that it can have toxic side effects in some situations, affecting the skin, brain and cells of both humans and pets.
- Environmental Working Group considers DEET, picaradin and IR3535 safe insect repellents, but only when properly applied.
- Most cases of serious side effects caused by DEET involve long-term, heavy, frequent or whole-body application of the repellent. But for some people, DEET can lead to adverse skin reactions, seizures and brain malfunction, fatigue, respiratory conditions and possibly even cancer.
- DEET can also be toxic to our pets and have a negative environmental impact.
- Some DEET alternatives that are also protective against insect-borne diseases and have a better safety profile include:
- Oil of lemon eucalyptus
- Citronella oil
- Soybean oil
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