[pct-l] Permethrin and Deet

[Justin West]

 I found the following onlineEPA.gov with regards t*o DEET:*

Human Health
Assessment
Toxicity
In studies using laboratory animals, DEET generally has been shown to
be of low acute toxicity. It is slightly toxic by the eye, dermal and oral
routes
and has been placed in Toxicity Category III (the second lowest of four
categories) for these effects.
[NOTE: For acute oral, dermal, ocular and inhalation toxicity:
Category I = very highly or highly toxic
Category II = moderately toxic
Category III = slightly toxic
Category IV = practically non-toxic]
Dietary Exposure
Because of its use pattern, people are not exposed to residues of DEET
through the diet.
Occupational and Residential Exposure
Based on DEET’s indoor/residential use pattern, handlers (mixers,
loaders, and applicators) are not exposed to DEET.
Human Risk Assessment
DEET generally is of low acute toxicity, and, based on the available
toxicological data, the Agency believes that the normal use of DEET does not
present a health concern to the general U.S. population (the Agency’s human
risk assessment has identified no toxicologically significant effects in
animal
studies.) DEET has been classified as a Group D carcinogen (not classifiable
as a human carcinogen.)


And surprisingly* Permethrin:*
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.

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.



Seems like Permethrin is more toxic than DEET, although it doesn't sound
like they have done much studying of DEET as it is classified (bizzarely) as
a strictly 'indoor residential use' pesticide