What’s the Best Bug Repellent?

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There's an unofficial but infamous season this time of year in New England (my native homeland, for those of you who don't know). In the weeks roughly between Mother's Day and Father's Day is a period the locals call black fly season. For those of you unfamiliar with these creatures, there's no overdramatizing their menace. They're deceptively minuscule but ubiquitous, and their bites can mutilate. I remember a couple from the Midwest moved to our neighborhood just before the school year. Come spring, they'd heard the many jokes and well-intentioned warnings but scoffed when they first saw the flies themselves. u201CThose gnats?u201D they asked incredulously. About a week or so later they were both covered in welts after spending the weekend doing yard work with no protection. The woman's hairline was chewed to oblivion. (These things tended to get around the neighborhood.) I still think of black fly season after all these years especially when I get questions from readers about bug season in their parts of the country. Increasingly, folks ask about a Primal alternative to chemical bug repellent.

The principle behind bug repellents, of course, is to repel. Whether chemically or naturally-derived, a repellent's job is to make you as unappealing to bugs as possible. And, yes, some people are more enticing. Mosquitos, for example, target their blood donors (actually it's the blood proteins they're after) by their smell in addition to lactic acid (mmm…human sweat) and carbon dioxide output. The respiration part explains why the little ones (and pregnant women) tend to get eaten alive out there while others in your party escape with nary a bite. Using genetically modified insects, researchers have also found that taste plays a part as well as smell for mosquitos.

The two most popular conventional repellents are DEET and picaridin (a.k.a. Bayrepel). The vast majority of what you buy in the store today use these as active ingredients. DEET, the most common repellent in the U.S. has been used since the late 1950s. Picaridin is far newer on the block, introduced in Europe in 1998 and in the U.S. in 2005.

In the U.S., DEET remains the repellent of choice, but there's plenty of reason to choose otherwise. Transdermal absorption of DEET in studies has ranged from 5-17% in humans, and absorption continues as long as the product remains on the skin. DEET has been linked to some fatalities in children who received multiple and extensive applications. It has also been identified as a neurotoxin, in that it inhibits the activity of cholinesterase, an enzyme of the central nervous system in both insects and mammals. A Duke University pharmacologist found evidence in rat studies that DEET exposure resulted in u201Cdiffuse brain cell deathu201D in regions governing u201Cmuscle movement, learning, memory and concentration,u201D poorer performance in physical and cognitive tasks, and u201Cbehavioral changesu201D when used long-term.

Although governmental and medical organizations like the CDC and American Academy of Pediatrics offer no conditions in their recommendation of DEET, I'd say the risks are enough to give this Primal mind pause.

Obviously, the more often and higher concentrations you use, the higher the risk. I'd suggest reserving DEET products for limited occasions if alternatives don't work for you in a given situation. Also, more vulnerable members of the population like children, pregnant women, and those with autoimmune/neurological disorders should avoid using DEET. On a side note, some mosquitos are developing a resistance to DEET, including those associated with yellow fever.

There's also a repellent called permethrin, which is approved for use on clothes only. Permethrin actually kills as well as repels mosquitos and ticks, which means it's clearly nothing to fool around with. Be advised that even after your wash your clothes, the insecticide remains. For the average person, there's probably little if any need for the risk inherent with this strong a product.

Less is known about Picaridin. So far, studies demonstrate low toxicity (PDF), and it appears to be the safest choice among conventional repellents. Check out the fact sheets, but little is published (in this country anyway) regarding ongoing study and safety reports.

According to clinical research, your best bet for minimizing bug bites with naturally derived repellents are those with active ingredients taken from essential oils. Oil of lemon eucalyptus appears to be the most effective, but this can be irritating to the skin of young children, particularly in higher concentrations. In a USDA study (PDF) comparing natural repellents against DEET products, a commercial repellent containing oil of lemon eucalyptus (Repel) was more effective than the low concentration DEET product marketed for children. Geraniol, a compound found in geranium plants, also looks promising as does peppermint oil. Geranium and peppermint oils at 100% concentration offer full protection, but the effect remains for a relatively short amount of time (2 hours and 45 minutes, respectively).

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