The following statements were issued by the Environmental Protection Agency in their 738-F-
06-012 Permethrin Fact Sheet, dated June 2006.
Text in black is EPA's and the text in blue is our
opinionated take.

"For the public health use, permethrin is the most widely used mosquito adulticide in the
United States because of its low cost, high efficacy, and low incidence of pest resistance.
Although permethrin alternatives are comparably priced and are likely to be as effective
as permethrin in many situations, they are not likely to universally substitute for all
permethrin uses because of labeling constraints or resistance concerns. The Agency
believes that the loss of permethrin would adversely affect the ability of mosquito
abatement professionals to control mosquitoes in some situation, such as agricultural-
urban interface and areas with known resistance to alternatives."

Let's take a moment to examine this statement. One could certainly come to the
conclusion that the EPA would rather we use an alternative to Permethrin, however,
because of bureaucratic red-tape, these alternatives will not become available. All
pesticides sold or distributed in the Unites States must be registered by the
Environmental Protection Agency (EPA), based on scientific studies showing that they can
be used without posing
unreasonable risks to people or the environment.

Although, the fact sheet, for the most part refers to the toxicity of Permethrin to be "below
their level of concern"
, it does contain the following statements and warnings..

"Health Effects
Permethrin is a member of the pyrethroid class of pesticides. Similar to other pyrethroids,
permethrin alters nerve function by modifying the normal biochemistry and physiology of
nerve membrane sodium channels. However, EPA is not currently following a cumulative
risk approach based on a common mechanism of toxicity for the pyrethroids. Although all
pyrethroids interact with sodium channels, there are multiple types of sodium channels
and it is currently unknown whether the pyrethroids have similar effects on all channels.
Nor do we have a clear understanding of effects on key downstream neuronal function e.
g., nerve excitability, nor do we understand how these key events interact to produce
their compound specific patterns of neurotoxicity. There is ongoing research by the EPA’s
Office of Research and Development and pyrethroid registrants to evaluate the
differential biochemical and physiological actions of pyrethroids in mammals. This
research is expected to be completed by 2007. When available, the Agency will consider
this research and make a determination of common mechanism as a basis for assessing
cumulative risk. Therefore, the human health risk assessment and RED document only
considered the effects of permethrin."

By this statement, its obvious that the EPA lacks the cumulative data to determine any
long-term effects, if any, that Permethrin may have on humans. A classic example of this
would be the use of "AGENT ORANGE" in Southeast Asia (Vietnam) during the 1960's as a
herbicide. It wasn't until years later, long after our soldiers and others returned did we
discover the many adverse conditions that are attributed to the exposure of Agent
In addition, a good quanity of products used in mosquito abatement also include Piperonyl
butoxide (PBO), a pesticide active ingredient that acts as a synergist.
Synergists are chemicals which, while lacking pesticidal properties of their own, enhance
the pesticidal properties of other active ingredients. Research studies are being
conducted in an effort to determine the level of toxicity when combined with Permethrin.

"Additionally, the Agency classified permethrin as “Likely to be Carcinogenic to Humans”
by the oral route. This classification was based on two reproducible benign tumor types
(lung and liver) in the mouse, equivocal evidence of carcinogenicity in Long- Evans rats,
and supporting structural activity relationship information."

"Aggregate short-term (1-30 days) non-cancer risk estimates, which include the
contribution of risk from chronic dietary sources (food + drinking water) and short-term
residential sources, exceeded the Agency’s LOC for toddlers exposed to permethrin
through food and drinking water, and through post-application exposure during high
contact activities on lawns and indoor surfaces. The risk driver for the aggregate non-
cancer risk estimate was post-application exposure to permethrin on treated indoor
surfaces (carpets)".

"The aggregate cancer risk estimate exceeded the Agency’s LOC for adults exposed to
permethrin through food and drinking water, and through postapplication exposure
during high contact activity on lawns and indoor surfaces. Similar to the non-cancer
aggregate risk assessment, post-application exposure to treated indoor carpets was the
risk driver."

"The potential for risk to terrestrial and aquatic plants from exposure to permethrin
cannot be assessed because toxicity data are not available. However, any toxicity to
plants would occur for reasons other than permethrin's insecticidal mode of action
because permethrin works as a neural toxin, and unlike insects, plants do not have neural
networks that could be affected".

"Permethrin toxicity data show that the compound is highly toxic to honeybees, as well as
other beneficial insects".

"Risk/Benefit Balance Analysis
The Agency also assessed the significance of permethrin use, and conducted a
risk/benefit balancing analysis. Given the significance of the use of permethrin and the
mitigated nature of the risks of permethrin, the Agency believes, on balance, that the
benefits of permethrin outweigh the risks. With respect to the ecological risks, the Agency
has reduced those risks by imposing various conditions that should reduce exposure of
aquatic species to permethrin. With respect to the benefits, permethrin offers substantial
benefits to users. In the agricultural area, permethrin provides a high benefit to the
agricultural industry because of its broad label and 1 day PHI. According to comments
received from various growers, the broad spectrum of pests that permethrin targets
makes its use highly beneficial since the agricultural industry has been losing a number of
insecticides, and the newer insecticides replacing them have chemistries that target
specific insects and are narrow in their spectrum. Further, permethrin has a 1 day pre-
harvest interval, which allows for effective pest control near harvest of registered crops.
Also alternatives to permethrin, such as the fourth generation pyrethroids, may pose a
greater risk to aquatic organisms because of their persistence in the environment".

This statement clearly determines the short duration of effectiveness of Permethrin.
When used for mosquito abatement, it acts as a direct contact killer, we know that the
residual effect can be measured in hours. For this reason, to achieve any degree of
success it must be applied on a daily basis, which is why you see that famous, smelly,
fogging truck often.

We all seem to really focus on Permethrin with little regards to that smelly catalyst that we
use to disperse the insecticide. The majority of fogging applications contain a Petroleum
Distillate Solvent.

We could spend a great deal of time discussing all of the precautions, such as drift factors
(product shouldn't be dispensed when wind speeds exceed 10 mph), water contamination,
workers dispensing precautions and the list goes on and on. Just take a couple of hours
to read the precautions the manufacturers have applied to the product.
In summary, these pesticides are designed to kill the adult mosquito, the ones that bite
you, on contact and have very low residual effects. When we review the recommended
amount of Permethrin that should be dispensed over a period of time, it doesn't require a
PHD to determine that we exceed this amount, when used in mosquito abatement. Now
lets take a common sense approach to this, if we are dispensing in quantities greater then
recommended wouldn't we also be increasing the risk factors of the product? With all that
being said, is there a place in mosquito abatement for these pesticides? You bet there is,
you and I both want to eradicate that pesky and potentially dangerous mosquito, but until
we are able to control their populations, the need for these pesticides exist. An
alternative to this problem would be to prevent a mosquito from becoming one in the first
place, wouldn't you say. By taking the steps to eliminate their breeding sites, we could
seriously hinder their ability to become that mosquito. With todays technology, we are able
to locate the breeding sources and their populations, with the use of Doppler Radar, and
therefore could realistically minimize their existence by eliminating those sites. We could
then limit our fogging to a tolerable level and rely upon the natural predators of the
mosquito, i.e. Bats, Dragonflies,etc., that we haven't killed with the pesticides, to assist in
taking care of the adults that managed to survive. Check out our
ABOUT US page to see
how this approach was successful in the early 1900' in our fight against Maleria. It can
happen, all that is required is the combined efforts of individuals and the community to
make it work. As an added benefit to this approach, if we could limit the amount of
necessary fogging, a big relief to your community's budget could be realized. At an
average cost exceeding $80.00 per gallon for this concoction and the average fogging
truck carries 11 gallons and then add in the overtime pay and equipment costs (most
spraying is done at night), you do the math. These funds could then be diverted to
cleaning up those breeding sites.  
Frio Nature Conservancy
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Let's begin with the Frio Nature Conservancy's stand on the use of Pesticides to control
Mosquitoes. We do not condone the use of toxic pesticides whether fogged or directly applied
to control the mosquito, however, we do understand the position that our Vector Control folks
face in their attempt to protect us from the mosquito. When we fail to control the mosquito, in
a more natural manner, in our own back yard and the mosquito population grows to an
intolerabe and dangerous size, we leave Vector Control no other alternative but to send out
the fogging trucks.
If we all did our part and with the technology we have today with Doppler
Radar, being able to locate the problem areas, Vector Control could limit their use of these
pesticides to targeted areas. In most areas of the country, Vector Control does not have the
resources or authority to enter upon private property in order to control those pesky and
widely disseminated to the public in all forums and using the mosquito's natural predators we
can make a difference.   
We Want Your Input
We have created a Poll to gather your input on the use of Pesticides, specifically used in
fogging, to control mosquitoes.

You can answer the poll and be able to make any comment that you care to.

This Poll will end on September 30, 2008 and the results will be made available to anyone

CLICK HERE to enter your vote.