Pyrethrin is one of two liquid esters derived from Pyrethrum
(feverfew) (C21H28O3 or
C22H28O5) that are used as insecticides.
Pyrethrum, a nonvolatile hydrocarbon related to kerosene, is a similar
insecticide derived from and chrysanthemum flowers.
The fact that they are
derived from plants causes some people to think - a point played up by
companies using this toxin in their products - that they are safe. Lots of
plants are toxic, some in small quantities, others in large. Just because
it comes from something lush and ornamental does not mean it can't be
lethal. Oleander, azalea, mistletoe, and foxglove are just a few of the
pretty - and highly toxic - plants with which we live.
a synthetic pyrethrin
(C21H20Cl2O3). In other words,
it is a man-made poison that is a copy of two poisons found in
chemical manufacturers make permethrin or extract pyrethrin for use in
their own products or for sale to other companies to use as an ingredient
in other products, their "brand" of pyrethrin or permethrin is given a
unique name. Some of the names you may see on such products
3-(2,2-dichlorethenyl)-2,2-dimethyl-, (3-phenoxyphenyl)methyl ester
Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl-2,2-dim
The use of these insecticides are
wide spread, including:
Ectoparasiticide: It has
a potential application for forest protection and vector control for the
control of noxious insects in the household and on cattle, for the control
of body lice, and in mosquito nets.
Control of larvae (and also adults and eggs) of chewing lepidopterous and
coleopterous insect pests on pome fruit, stone fruit, berry fruit, citrus
fruit, vines, olives, vegetables, cereals, maize, oilseed rape, cotton,
tobacco, soya beans, and in conifer nurseries; whiteflies and other
glasshouse pests on glasshouse cucumbers, tomatoes, and ornamentals; and
sciarid flies and phorid flies on mushrooms.
Also used for control of
crawling and flying insects (e.g. flies, ants, fleas, cockroaches,
silverfish, etc.) in public health, and in agricultural premises including
animals houses; and as an ectoparasiticide on animals.
Widely used in home and
garden pest sprays and in schools, both in the buildings and on the
long-lasting effects, the pyrethroid may be mixed with a fixative to make
it stay on plants and soil longer, and other chemicals, such as piperonyl
butoxide, which prevent the insects from detoxifying, and "inert
ingredients". One of the problems is that manufacturers are not required
to list the inert ingredients - even though they may themselves be highly
toxic or cause know allergic and other reactions in organisms exposed to
them - such as you, your children, and your pets.
Some insects have
developed ways to detoxify the naturally occurring pyrethrums encountered
when feeding on the nectar of feverfew and chrysanthemums, a not uncommon
adaptive response. Unfortunately, while insects and plants have had
millions of years to work out these survival pathways, we humans
An increasing number of
insects have developed high levels of resistance to pyrethroids, such as
cockroaches, head lice, and tobacco budworm, pear psylla, fall army-worm,
German cockroach, spotted tentiform leafminer, diamondback moth, house
fly, stable fly, head lice, and tobacco budworm. Many of these species are
resistant to more than one pyrethroid. Because insects reproduce - and
adapt - far more quickly than do vertebrates, they are far better able to
evolve defenses against the toxins we throw at them, resulting in an ever
expanding range of poisons developed and thrown into our
like all toxins, are indiscriminate: they affect all the organisms who
come into contact with them in the air, on plants, on the ground, in the
soil, and in the water. While your local grower - or you - may be applying
it to deal with a specific pest, the products affect everything around it.
And, since particulates are easily airborne, they travel, often
great distances, from the actual point of application.
Inhalation: coughing, wheezing,
shortness of breath, runny or stuffy nose, chest pain, or difficulty
rash, itching, or blisters.
Long term effects:
disrupts the endocrine system by mimicking the female hormone,
estrogen, thus causing excessive estrogen levels in females. In human
males, its estrogenizing (feminizing) effects include lowered sperm
counts. In both, it can lead to the abnormal growth of breast tissue,
leading to development of breasts in males and cancerous breast tissue in
both male and females.
include: tremors, incoordination, elevated body temperature, increased
aggressive behavior, and disruption of learning. Laboratory tests suggest
that permethrin is more acutely toxic to children than to
Other: A known
carcinogen. There is evidence that pyrethroids harm the thyroid gland. Causes chromosomal
damage in hamsters and mice; deformities in amphibians; blood
abnormalities in birds.
Skin Contact: skin irritation.
effects: A known carcinogen.
Ingredients: Some known ones include:
(agricultural insecticides such as Pounce, Ambush 2E and Ambush 50):
eye and skin irritation, headaches, nausea, confusion, tremors, and
anxiety in exposed humans. In laboratory tests, xylenes have caused
kidney damage, fetal loss, and skeletal anomalies in
(head lice cream rinse Nix; regulated as a drug not as a pesticide): a
skin sensitizer, causes eye, skin, digestive, and respiratory
(household insecticides such as Flea-B-Gon Total Flea Killer Indoor
Fogger and Ortho Total Flea Control 2):. causes respiratory, skin, and
eye irritation and depresses the central nervous system. It is also a
severe fire hazard.
(household insecticides such as Raid Yard Guard Outdoor Fogger V and Off
Yard and Deck Area Repellant) : “extremely flammable” and short-term
exposure causes irritation, nausea, drowsiness, convulsions, and
So, what's the big deal?
While pyrethroids may be
amongst the least toxic of insecticides, they are an excitatory nerve
poison, acting upon the sodium ion channels in nerve cell membranes:
- by sending a train of
impulses rather than a single one, they overload the pathways, blocking
the passage of sodium ions across cell membranes; similar in action to
organophosphates (which include the now banned DDT); inhibits ATPase, which affects
the release of acetylcholine, monoamine oxidase-A and
- inhibits GABAa
receptors, resulting in convulsions and excitability (and more 'minor'
problems such as sleep disorders);
- known to be
- liver damage
- cause chromosomal
abnormalities in mice and hamsters;
- are highly toxic to
insects, fish, and birds;
- mimic estrogen,
leading to estrogen
dominant health problems in females and feminizing effects in males,
including lowered sperm counts and abnormal breast development;
- sublethal doses have
produced a wide array of abnormal behaviors, including aggression, and
disruption in learning and learned behaviors
The American Heritage® Dictionary
of the English Language, Third Edition
WEB's On-line Medical Dictionary
from Insecticide Fact Sheet, Journal of Pesticide Reform, Summer
1998, Vol 18, No 214l
Spectrum Labs Chemical Fact Sheet