Travel Reference
In-Depth Information
United States in 2005. (It had been introduced earlier in Europe.) Both agents are highly
effective against mosquitoes and are also effective against ticks and chiggers. They are not
effective against flies.
In a comparison of mosquito repellents carried out in 2002 (before picaridin was intro-
duced), DEET-based products provided complete protection for the longest time. A for-
mulation containing 23.8 percent DEET had a mean complete-protection time of 301.5
minutes (five hours.) A soybean-oil-based repellent, the second most effective, protected
against mosquito bites for an average of 94.6 minutes. An IR3535-based repellent protec-
tedforanaverageof22.9minutes.Allotherbotanicalrepellentstestedprovidedprotection
for less than twenty minutes. Repellentimpregnated wristbands offered no protection.
The duration of effective protection from mosquito bites varies with the concentration
of DEET in the preparation:
A product containing 23.8 percent DEET provided an average of five hours of protec-
tion.
A product containing 20 percent DEET provided almost four hours of protection.
A product with 6.65 percent DEET provided almost two hours of protection.
A product with 4.75 percent DEET provided roughly 1.5 hours of protection.
DEET is available in concentrations that range from 5 to 100 percent, although the pre-
parations most commonly used have concentrations in the range of 30 percent.
DEET and picaridin are removed by sweating, absorption, evaporation, wiping, and
rain and must be reapplied several times a day. However, two long-lasting formulations of
DEET have been developed: a microencapsulated product in which DEET is encased in a
protein shell, and a preparation in which the agent is dissolved in a polymerized lotion.
Ultrathon is a polymer-based product containing 34.34 percent DEET. It is produced by
3M Corporation and is the standard-issue insect repellent for the U.S. military. It is gener-
ally accepted to last twelve hours. The microencapsulated product is Sawyer® Controlled
Release Insect Repellent, a 20 percent DEET preparation that was selected by Consumer
Reportsasthemosteconomicallotioninsectrepellent(fourcentsanhour)becauseitlasted
solong.Sawyerclaimsthisagentiseffectiveforatleastelevenhoursaftereachapplication
but may last longer.
DEETisabsorbedthroughskin,and10to15percentoftheunmodifiedpreparationscan
be recovered from urine. (Both of the long-acting preparations are associated with much
less absorption.) Allergic reactions to this agent, including bullous eruptions, contact ur-
ticaria,andanaphylaxis,havebeenreported.Toxicencephalopathywithgrandmalseizures
has occurred, particularly in infants and children. However, in recent years extensive in-
vestigations of DEET have been carried out by a number of agencies because it is used so
extensively. The Environmental Protection Agency (EPA), which is responsible for testing
suchagents,andtheCDCstatethatpreparationscontaining30to35percentconcentrations
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