Visiting a tropical country may be the dream of a lifetime, but you don’t want to transform it into a nightmare of itching and scratching - or worse.
Lots of things bite, but the mosquito is the most common. It may be harmless in cooler climates but in some parts of the world, it can be lethal. You should do everything in your power to avoid malaria, dengue and now Zika.
You keep them from biting you, and there are several ways you can do that.
You can use a mosquito net when you sleep, making sure the tiny beasts don’t nibble away at you in the night. Turning on the air conditioning, if there is any, helps too.
You can also make sure your body is covered, especially at dawn and dusk. That means wearing socks, long sleeves and trousers when mosquitoes are most present).
Or, and this is the most common choice, slather a product all over yourself that will kill or maim mosquitoes or make them escape in horror.
According to the Centers for Disease Control (CDC), four main products work to keep mosquitoes away: Picaridin (known as icaridin outside the US), oil of lemon eucalyptus and something called IR3535 and, of course, DEET.
Let’s look at each in turn.
Picaridin is recommended by the World Health Organization (WHO). It is considered less toxic than DEET (whose toxicity is still being debated). It evaporates from skin faster, doesn’t irritate the eyes and isn’t as strong smelling. A working group from the Environmental Protection Agency considers it a good alternative to DEET.
Oil of lemon eucalyptus (OLE) is one of several natural oils recommended as a mosquito repellent. At slightly stronger concentrations, some tests have shown that OLE is as effective as DEET. It doesn’t last as long, however, nor is it effective against West Nile virus, sand flies and 'no-see-ums'. Other oils include citronella, soybean oil and geranium oils and while they may be less likely to cause side effects, you do have to apply them quite often.
The third common mosquito repellent is IR3535, a potent substance that can irritate your eyes and harm plastic. Still, the Environmental Protection Agency’s (EPA) Working Group says it poses few other safety risks. (Really? But dissolves plastic?) It is considered as good as DEET against deer ticks and some of the mosquitoes that carry the West Nile virus.
And finally, everyone’s favorite whipping boy, DEET, the most common mosquito and tick repellent and possibly the most controversial. While health authorities admit it is strong and can damage plastic and rubber, they still consider it safe - although they do admit that in large doses or over time it can produce adverse reactions in about one per 100 million persons. (‘They’ are the CDC, the EPA and the WHO.)
That said, DEET is known to irritate eyes and used in large doses or for a long period of time it can produce neurological damage but - extremely rarely, with adverse reactions of about
According to the EPA, “DEET is generally safer than many people assume and remains a viable option for people in areas infested with disease-carrying pests.” The big advantage of DEET of course is that it lasts a long time so you have to apply it less often and it is more effective.
Still, DEET has significant critics. A study by Duke University pharmacologist Mohamed Abou-Donia details an extensive list of neurological damage caused by DEET and other conventional insecticides, from memory loss to tremors to slurred speech. French studies say it can harm animals, children and pregnant women.
You’ll have to make up your own mind: is it truly safe, or is this an example of business funding science and coming up with ‘acceptable’ results? I do use DEET on occasion, but I spray it on my hands and then rub it on - I never apply it directly to my body. But I’d welcome alternatives that really work.
These four products are those officially recommended by the CDC but there is one more: permethrin. The FDA approved it recently although it’s in widespread use in Europe and Asia. The EU, however, lists it as an endocrine disruptor, and it's been shown to cause tremors in dogs and cats, according to the National Pesticide Information Center. Having read this, and having used permethrin, I am concerned. One note: I would only use it on my clothes, never on my skin. A product containing permethrin is Sawyer Premium.
Some of the major concerns people voice around DEET are environmental.
When DEET breaks down into nature, what’s left behind is less toxic that the DEET itself. But DEET is used often so it does make its way into waste water and through that into other waters. It can be toxic to fish and insects at extremely high levels but isn’t considered toxic to birds.
According to an EPA review in 2014, DEET meets current safety standards - although there is plenty we don’t know. “We continue to believe that the normal use of DEET does not present a health concern.” More tests are planned and who knows - they may reveal something else.
The Sierra Club concurs, arguing that malaria or West Nile virus or Lyme disease (from black-legged ticks) are far worse dangers than DEET - which, it says, is toxic to household pets so don’t use it around your cats. (It has been known to kill cats.)
Right. Your choice.
In 2015, almost half a million people died from malaria. Half a million cases of dengue develop into hemorrhagic fever, killing 25,000 a year. And the impacts of Zika have been well documented. You have to pit this data against the impact of repellent to make up your mind.
Popular Science: Is DEET Safe to Use?
National Pesticide Information Center: DEET Fact Sheet
EPA: DEET Hub
Sierra Club: Keeping Bugs (and Bears) at Bay
Green America: Living Green