If  you have ever been to tropical areas you’ll probably have used DEET. Especially in those regions of the world where malaria is a threat, an effective mosquito repellent is a must. And now that the West Nile virus has made its entrance in the US it may be a required for domestic use too.

Anyone who has sprayed their skin with the chemical repellent and then picked up a nylon jacket or plastic shades may have seen the item fall apart in their hands.

DEET can damage all kinds of synthetic items, from flipflops to water bottles. It may take of your nail polish or disintegrate your tights.

Which begs the question, what about the health concerns regarding the substance itself? Is it really safe to use?

What exactly is DEET?

It’s the most common synthetic insect repellent. Chemically known as N,N-diethyl-m-toluamide; also called N,N-diethyl-3-methylbenzamide. Because of these scientific names it is better known by its acronym, DEET.

DEET was developed for use by the U.S. Army during World War II in 1946 and has been registered as a pesticide since 1957 when it became available to the consumer market.

Why is DEET often recommended?

Natural alternatives such as plant extract-based substances exist. These include citronella oil and p-menthane-3,8- diol (PMD). While it is true that these compounds are also good at repelling insects there is a downside.

Most plant-based repellents are made up of volatile constituents which makes them not effective over long periods of time. In other words, for you to stay protected you have to keep on applying these repellents.

DEET is the most effective repellent because, contrary to other (natural) insect repellents the synthetic compound DEET works for hours on end. Simply put, DEET is the best bug repellent and only really effective substance we’ve got.

For this reason it is the most widely used repellent and as PubMed states,

generally considered to be the “gold standard” repellent, providing long-lasting protection of up to 8 hours from time of application [2].

 

Does DEET work on mosquitos only?

DEET is known to repel a wide range of insects including mosquitoes, flies, ticks, fleas, chiggers, no-see-ums, midges and gnats.

DEET products

World’s most well known mosquito repellent comes in various forms such as sprays, lotions, liquids, and impregnated materials  such as wrist bands,  nets, towelettes and roll on devices. Products used for direct application to the skin contain from 4% to 100% Deet. Most formulas however, contain between 10% and 30%.

As of 2005, 30 different manufacturers offered over 100 products for sale that contained DEET.

The U.S. Environmental Protection Agency (USEPA) estimated that in 1990 about 30 percent of Americans used DEET every year. The estimated use in 2000 was between 5 and 7 million pounds (J Pesticide Reform, 2005, Fall).

How does Deet work?

Instead of killing mosquitos Deet works by making it hard for the bugs to smell you. DEET is one of the few registered pesticides that is applied directly to the skin and clothing.

The way DEET works is to prevent special receptors in the insects’ antennae from functioning normally so they cannot detect the presence of the host they are seeking to bite (J Pesticide Reform, 2005, Fall).

According to Consumer Reports tests, “the top six repellents protected against deer ticks and mosquitoes for seven hours or more.”

How long does DEET work?

It depends on the concentration. The higher the percentage of DEET present in the product, the longer it works.

Generally products with 10 percent DEET are effective for about two hours.  It is said that a DEET concentration of approximately 24 percent provides five hours of protection on average.

However, if you are going to tropical locations it is recommended to use spray containing at least 20% DEET.  Even a repellent with a 15% concentration is claimed to put you at risk of malaria and Dengue fever.

WebMD mentions:

Repellents with 23.8% DEET protect wearers for about five hours, according to a study led by Mark Fradin, PhD, a researcher with Chapel Hill Dermatology.

Senior lecturer in medical entomology at the London School of Hygiene & Tropical Medicine, Dr James Logan stresses that low level DEET products are not very effective. He urges to use repellents containing 20-50 % DEET in tropical areas.

Don’t believe the scaremongers

If you have to believe the scary tales of people like Dr. Mercola you will think twice before putting Deet on your skin.

A wide range of websites warn for the dangers of Deet mosquito repellent. Some tell you that the substance is so harsh, it kills mosquitoes which is false.

Others make claims such as:

“DEET pumps through your nervous system and has been proven to kill brain cells”

Recent research demonstrates that all Deet does, especially upon reading such information, is make people nervous as this article by the Los Angeles Times demonstrates, DEET repels bugs, worries consumers.  It however, does not affect our nervous system.

Is DEET really safe?

According to some sources traditional insect repellents such as DEET can be hazardous. This conclusion is commonly based on the following assumptions and findings.

• DEET has been tested on laboratory animals and on human cells and has been shown to cause damage to DNA. “The results indicate that dermal administration of DEET could generate free radical species hence cause DNA oxidative damage in rats.” (PubMed)

• Some governments limit DEET concentration after reports of DEET use causing a type of brain disease called encephalopathy. To put this in perspective, since 1957 and the hundreds of millions of applications of the substance to the skin since that time there were only 14 cases of encephalopathy associated with DEET. Which, in relative terms, is an extremely small number. Also, experts point out that “it is difficult to point to DEET as the culprit.”

• The two pregnant women who gave birth to babies with problems were known to use “large amounts of DEET”.

• DEET was shown to cross the placenta in pregnant laboratory animals and exposure to DEET in amounts equivalent to what is typically applied to human skin was shown to affect their behavior and nervous systems, reducing sensory and motor skills.

• There’s one human trial on the safety of DEET, conducted on pregnant women in Thailand. It showed evidence of traces of DEET in the children, suggesting that the substance could cross the placental barrier there were however no differences in the health of the babies between the DEET treatment group and the control group babies.

• This study demonstrated that researchers, following women in Thailand who used DEET from their second trimester of pregnancy onward DEET reduced the incidences of malaria. Also, babies born to moms who used DEET didn’t suffer from birth defects or even differ from babies born to moms who didn’t use DEET.

• DEET has been shown to cause synergism when mixed with certain other pesticides like permethrin and Malathion.

• DEET has also been suspected of being an environmental contaminant and might be harmful to the developing chicks of birds (J Pesticide Reform, 2005, Fall).

 

Despite the horror stories, DEET is generally considered safe

The aforementioned PubMed study also mentions  “some rare reports of severe reactions in people”.

It also refers to DEET causing plastic to melt and damaging mobile phones and glasses.  Other common disadvantages of DEET are the unpleasant odor and skin sensation after application.

In conclusion, although these proclaimed health risks sound scary and serious in reality they are not that realistic. Often such warnings are taken out of context.

Joe Conlon, PhD, technical advisor to the American Mosquito Control Association says that DEET,

has been in use for over 40 years and has a remarkable safety record. Only few hospitalizations have been reported, mainly due to gross overuse.

 

Meta study concludes DEET is safe

Dr Logan, leading a review of existing studies concluded that

There is insufficient evidence to show that DEET is unsafe for human use. If DEET caused serious health problems, we would know about it by now.

According to the researchers, “the benefits of avoiding disease-spreading insect bites outweigh any risks associated with applying DEET to the skin.”

EPA on DEET

According to the Environmental Protection Agency the substance is safe when used according directions.

EPA continues to believe that the normal use of DEET does not present a health concern to the general population, including children.

 

What do other sources say?

• The renowned health website WebMD also refers to EPA and adds that DEET has caused rare toxic reactions when not used as instructed.

• Most sources agree that DEET shouldn’t be applied to babies less than 2 months old.

• The American Academy of Pediatrics has advised against using repellents with DEET concentrations higher than 30% on any kids.

• Consumer Reports Health advice against using a repellent with more than 30% DEET.

 

Does Deet have no risks or side effects at all?

As with all substances, even the mildest, skin irritation may occur. We are all different. Obviously, accidents can happen. Breathing in or swallowing the bug spray can cause bug spray poisoning.

Wrapping it up

Most experts agree that the benefits of using DEET outweigh the (potential) downsides. Sure it doesn’t smell like roses and it may feel unpleasant on your skin.

But by avoiding its use or using too little you are likely to put yourself in harmful situations.

Also make sure to use a repellent with an appropriate concentration to guarantee its efficacy.

Scientists are working on natural alternatives that are just as effective. Until that time, keep spraying and remember,  if not just truly annoying, mosquitoes are the world’s most deadly animals.

Read this to learn more about proven effective ways to make your yard less attractive to mosquitoes.

 

 

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Have you ever returned from the woods, covered in mosquito bites, while your friends are somehow untouched?

Or your significant other doesn’t seem to be bothered at all during that hot summer night while you lie awake from the buzzing while suppressing the urge to scratch your itchy welts.

You’re probably among the 20% of people who are naturally attractive to mosquitoes. According to other experts such as Jerry Butler, PhD, professor emeritus at the University of Florida this number is a bit lower.

“One in 10 people are highly attractive to mosquitoes” .

It can be annoying to feel like ‘they’ always have to have you but it’s a fact, some people are more prone to mosquito bites than others. Certain individuals somehow seem to attract them more.

I am one of those people. Sadly the pesky bugs like me a lot.  But how come? What is it that they like to bite me and not my girlfriend?

There are various reasons. In fact there’s a huge range of factors in play.

Scientists are researching which compounds and odors people exude that might attract mosquitoes. With 400 different compounds to examine, researchers are just scratching the surface of getting a clear view on what really makes mosquitos favor certain people.

Mosquitoes use scent, heat, carbon dioxide,  moisture, and vision to locate hosts.

Read on to discover some of the factors which may be making you look like a delicious dinner to the little flying annoyances.

12 reasons why mosquitoes bite some people more than others

Genetics

Unfortunately, your genetics play the biggest role in how likely you are to be bitten by a mosquito. Scientists estimate that up to 85% of the reason why you’re being bitten by mosquitoes is due to your genetic makeup.

So how attractive you are to mosquitoes is largely out of your control. Until we find ways to modify genetics, you’re stuck with the genes you’ve been given by your parents.

According to WebMD

genetics account for a whopping 85% of our susceptibility to mosquito bites.

 

Factors that determine if you are mosquito magnet are..

Blood Type

A study showed that mosquitos landed nearly twice as often on people with Type O blood as on those with Type A blood. Type B blood falls somewhere in between Type O and Type A.

Not only blood type plays a role in your attractiveness to mosquitoes.

Over 80% of people secrete a chemical signal that can be used to determine what type of blood that they have. Those who secrete the chemical signal are more likely to be bitten, no matter what type of blood they actually have.

Metabolism

Researchers have found that if you have high concentrations of cholesterol or steroids on your skin’s surface you are more attractive to mosquitos.

This has to do with your metabolism. Human skin is directly involved in cholesterol metabolism. In fact, our skin contains approximately 11% of all the cholesterol and steroid hormones are synthesized from cholesterol.

Carbon Dioxide

Mosquitoes are keen to detect the carbon dioxide that you exhale with every breath. They are so sensitive that they can detect someone breathing from over 150 feet away.

People who breathe more often are more likely to attract mosquitos. In general, the larger you are, the more carbon dioxide you exhale. That’s why children are less likely to be bitten than adults.

In addition to carbon dioxide we excrete a so called semiochemical called nonanal. This triggers their sense of smell and is how they find us.

Body odor

Your skin releases volatiles which guide certain mosquito species to its host.

More specifically, a chemical present in your breath called acetone, etradiol which is a breakdown product of estrogen, and lactic acid which is part of your sweat all attract mosquitos. Some people excrete more of these substances than others.

Sweating

Mosquitoes aren’t just sensitive to carbon dioxide; they can also smell uric acid, lactic acid and ammonia that are in your sweat. They are also able to detect people with a higher body temperature.

When you exercise, your body builds up excess lactic acid and increases your body temperature. These changes in your body are like ringing the dinner bell for mosquitoes. Genetics play a role in lactic acid production, so some people are more vulnerable than others.

Bacteria

Skin bacteria are also particularly appealing to mosquitoes. Research has shown that having increased levels of certain types of bacteria will lead to an increased susceptibility to mosquito bites.

Not every type of bacteria will lure in mosquitoes though. Large amounts of unattractive bacteria types have actually been shown to repel mosquitoes.

As it seems some mosquito types do have a taste for the bacteria present on sweaty feet. This also explains why your feet and ankles are so often targeted by the bugs.

So instead of tossing your smelly socks away from the bed you may want to drop them in the laundry basket before hitting the sack. Taking a quick foot bath may help too.

Consuming Alcohol

Drinking a single beer is likely to increase your chances of being bitten by pesky insects. Whether it’s the increase in body temperature, or the increase in ethanol found in your sweat, no one really knows.

Scientists have been unable to find a correlation between any one factor caused by drinking and an increase in mosquito bites. The only thing that’s certain is that if you drink, you’re going to be bit. Here’s a study that found that drinking alcohol stimulates mosquito attraction.

Pregnancy

Pregnant women are almost twice as likely to be bitten by a mosquito. This is more than likely due to the fact that pregnant women exhale much more carbon dioxide.

Pregnant women also have higher body temperatures. An increase of just over a single degree in body temperature increases their likelihood of mosquito landings. Read more on PubMed.

Color of Your Clothes

This one is probably the hardest to believe, but James Day, from the University of Florida, claims that clothing color plays a role in how often people are bitten. He postulates that mosquitos use sight as well as smell to locate victims.

Colors that stand out, like black and red, may increase your chances of being bitten. Wearing greens and browns may help to camouflage you, protecting you from being seen by the winged assailants.

Movement & Excercise

Similarly, when you move, you are easier to spot. Mosquitoes will recognize you as a living being providing them with the desired blood. After all, they use sight as their first detection method.

Now you can try to lie still in bed but some people just move a lot. I can’t sit still and when in bed I tend to roll from side to side to my back until asleep.

It’s especially after exercising that you will become a mosquito magnet. Let’s say you have been running around the basketball court. Mosquitos have noticed you and lock on.  Now you are panting from the physical strain. Carbon dioxide from your heavy breathing has them closing in. The lactic acid present in your sweat makes sure all the mosquitos on the block know where to find you.

Being less repellant

New research emphasizes another way of thinking. Jonathan Day, professor of medical entomology at the University of Florida says that according to the latest insights it’s not so much what makes you attract the bugs but what makes you repel them.

Some people are just more naturally repellant. They are theorized to produce more dermal chemicals that mask the cues mosquitos use to find us.

Some people seem to naturally avoid mosquitos with no effort at all on their part. Scientists have begun to study these people to determine why this is. They have discovered some people secrete natural repellents that the mosquitoes don’t seem to like.

These natural compounds are being researched in order to synthesize them for everyone’s benefit. The next generation of mosquito repellants may actually be born from genetics, rather than unnatural chemical compounds.

According to scientific research, human beings are differentially attractive to mosquitoes and other biting insects.

Laboratory studies and clinical trials have demonstrated that this can be attributed partly to the fact that some people’s bodies produce more natural repellent chemicals.

The so called ‘arm in cage experiment’ found that certain repellents naturally present in humans, so called human-derived repellents consist of aldehydes and ketones.

• The clinical trial conducted by James Logan and John Pickett (Vince, 2006) basically tested body odor. Two different test persons put one hand into each end of a cage and the researchers observed which hand the mosquitos preferred and which not. By examining the less desirable person further they were able to find naturally present body chemicals that may be of help in producing a natural insect repellent.

 

Conclusion

Who would have thought. Sipping beer in your short sleeved hawaii shirt on a hot evening will make you attractive to the ladies. The mosquito ladies that is.

If you’d like to avoid a rash of nasty mosquito bites, limit physical exertion, wear shades of green and don’t forget the bug spray. Other than that, there really isn’t much you can do to avoid the wrath of these tiny winged vermin. Once you’ve been bitten you may want to use one of the many mosquito bite remedies for relief.

Photo by Lolo from Tahiti.