APPENDIX II-M:
Pyrethrins/Pyrethrum Factsheet:
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
14
●
I N S E C T I C I D
E F A C T S H E E T
Caroline Cox is
NCAP’s staff scientist.
BY CAROLINE COX
Pyrethrum
and pyrethrins have
been
used as insecticides since at least
18001
and for decades have been the
most
commonly used home and garden
insecticides
in the U.S.2,3 Pyrethrum
is
a natural insecticide, an extract
made
from two daisy-like flowers,
Chrysanthemum cinerariaefolium
and
Chrsanthemum cineum.
Pyrethrins
are
the six insecticidally active compounds
in
pyrethrum.1 (See Figure 1
for
two examples.) Pyrethrins are
mainly
used as indoor sprays, pet
shampoos,
and aerosol bombs to kill
flying
and jumping insects.1 Although
pyrethrins
are natural insecticides, they
do
pose important hazards to human
and
environmental health. This article
summarizes
those hazards.
Pyrethrin
insecticides often contain
piperonyl
butoxide, a chemical that
increases
the potency of pyrethrins.4
PYRETHRINS/PYRETHRUM
Pyrethrins and pyrethrum are the most
frequently used home and garden insecticides in the
in indoor sprays, pet shampoos, and
aerosol bombs to kill flying and jumping insects.
Pyrethrins are a common cause of
insecticide poisonings. According to a
(EPA) survey of poison control
centers, they cause more insecticide poisoning incidents than any other class
of
insecticides except the
organophosphates. Symptoms include headaches, dizziness, and difficulty
breathing.
Pyrethrins can trigger
life-threatening allergic responses including heart failure and severe asthma.
In laboratory animals exposed through
eating, by injection, or through breathing, pyrethrins have caused anemia.
Experiments with dairy cows suggest
that nursing mothers exposed to pyrethrins can pass them on to their children.
Pyrethrins disrupt the normal functioning
of sex hormones. They inhibit binding of sex hormones to human genital
skin and proteins in human blood.
Pyrethrins are classified as “likely
to be human carcinogens” by EPA because they cause thyroid tumors in
laboratory tests. Farmers who use
pyrethrins have an increased risk of developing leukemia.
Pyrethrins are extremely toxic to
bees, fish, and other aquatic animals.
Following indoor treatments,
pyrethrins have persisted up to 2 1/2 months in carpet dust.
A
large family of insecticides, the
synthetic
pyrethroids, are structurally
similar
to pyrethrins but have been
chemically
modified to make them
more
toxic and more persistent.1 For
information
about the hazards of three
commonly
used synthetic pyrethroids
see
JPR 14(2): 28-34 (cyfluthrin); JPR
16(2):
15-20 (cypermethrin); and JPR
18(2):
14-20 (permethrin).
Use
In
the early part of the twentieth
century
pyrethrum was “the most commonly
used
household insecticide.”2
The
most recent U.S. Environmental
Protection
Agency (EPA) home and
garden
pesticide survey estimated that
over
240 million of these applications
are
made annually in the
than
any other insecticide.3 There are
more
registered uses for pyrethrins
than
for any other insecticide.5 Worldwide,
about
200,000 kilograms (440,000
pounds)
of pyrethrins are used each
year.6
Other
than home and garden uses,
pyrethrins
are used on a variety of
The
health and environmental hazards
of
piperonyl butoxide will be summarized
in
the summer 2002 issue of the
Journal of Pesticide Reform.
Figure
1
Two of the Pyrethrin Esters
pyrethrin I
O
O
O
pyrethrin II
O
O
O
O
O
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
15
Propane
is used as an inert propellant in pyrethrin
products.
(See footnote 1 for some examples.) It can
cause
dizziness when inhaled. It is also “extremely flammable”
2
and easily ignited by heat, sparks, or flame.2
Isobutane
is also used as an inert propellant in
pyrethrin
products. (See footnote 3 for some examples.)
It
depresses the central nervous system and can cause
dizziness
when inhaled. Like propane, it is “extremely
flammable”4
and easily ignited.4
Hydrotreated
light petroleum distillates
(hydrotreated
kerosene) are used as an inert solvent
in
pyrethrin products. (See footnote 5 for some examples.)
The
Chemical Abstract Services number for
this
solvent is 64742-47-8. This solvent has caused skin
tumors
when applied to the skin of laboratory mice.6
Hydrotreated
heavy naptha (white spirits) is also
used
as an inert solvent in pyrethrin products. (See
footnote
7 for some examples.) The Chemical Abstract
Services
number for this solvent is 64742-48-9. It is
damaging
to kidneys and the nervous system.8 In
a
recent
laboratory study, the offspring of animals exposed
to
white spirits developed “long-lasting and possibly
irreversible
changes” in brain cells. This damage to
the
brain was caused by an inability to maintain normal
calcium
concentrations.9
1.
Whitmire Micro-Gen. 1998. MSDS: P.I. Contact Insecticide.
www.wmmg.com/pest/products/pdf/MSDS/pi.pdf.;
Value Garden Supply.
Undated.
MSDS: Black Leaf Home Insect Fogger.
www.valuegardens.com/msds/Home%20Insect%20Fogger.pdf;
Amrep,
Inc.
1997. MSDS: Misty Fog Plus Fogger. www.amrep.com/ii/products/
msds/aerosols/476.pdf.
2.
Hazardous Substance Data Bank. 2001. Propane. http://toxnet.nlm.nih.gov.
3.
www.valuegardens.com/msds/Home%20Insect%20Fogger.pdf;
Amrep, Inc.
1997.
MSDS: Misty Fog Plus Fogger. www.amrep.com/ii/products/msds/
aerosols/476.pdf.
4.
Hazardous Substance Data Bank. 2001. Isobutane. http://
toxnet.nlm.nih.gov/.
5.
Cardinal Chemical Company. Undated. MSDS: Py-Dry.
www.cardinalproproducts.com/MSDS/PY-Dry%20msds%202.pdf;
Aventis.
2001.
MSDS: Pyrenone 25-5 Public Health. www.adapcoinc.com/pdf/
PYR25m.pdf
Southern Agricultural Insecticides, Inc. 1997. MSDS: Natural
Pyrethrin
Concentrate. www.southernag.com/ms1040.pdf;
Co.,
Inc. 2001. MSDS: Pro Exterminator Crawling & Flying Insect Killer.
www.timemist.com/proexterminator/msds/ProExtCrawlingFlying.pdf;
Companies,
Inc. 2001. MSDS: Country Vet Farm & Home CV-38 for
Insect
Control. www.country-vet.com/products/347300CV.pdf
6.
International Agency for Research on Cancer. 1989. Occupational exposures
in
petroleum refining. IARC
Monographs 45:39. http://193.51.164.11/
htdocs/monographs/Vol45/45-01.htm.
7.
Whitmire Micro-Gen. 1998. MSDS: P.I. Contact Insecticide.
www.wmmg.com/pest/products/pdf/MSDS/pi.pdf;
8.
United Nations Environment Prog. et al. 1996. White spirit (Stoddard
Solvent).
Environmental Health Criteria 187.
Health
Organization. Pp.73-75, 77-78, 90-128.
9.
Edelfors, S., U. Hass, and A. Ravn-Jonsen. 1999. The effect of in vitro
exposure
to white spirit on [Ca+2] in synaptosomes from
rats exposed
prenatally
to white spirit. Pharmacol.
Toxicol. 84: 197-200.
HAZARDS
OF INERT INGREDIENTS
agricultural
crops and for structural and
public
health pest control. The amount
used
in agriculture is small relative to
the
other uses.7 (See Figure 2.)
Mode of Action
Pyrethrins,
like all members of the
pyrethroid
insecticide family, kill insects
by
disrupting their nervous systems.
Pyrethrins
are toxic to the “sodium
channel,”
the cellular structure
that
allows sodium ions to enter a cell
as
part of the process of transmitting
a
nerve impulse. This leads to repetitive
discharges
by the nerve cell which
causes
paralysis and death.8 DDT and
related
insecticides have the same
mode
of action.9
Nerves
in humans and other mammals
are
also susceptible to pyrethrin
poisoning.
However, mammals
have
enzymes that more rapidly
detoxify
pyrethrins into compounds
that
don’t disrupt the nervous
system.10
Figure
2
Pyrethrin Use in California
Source:
Calif. EPA. Dept. of Pesticide
Regulation.
2001. Summary of pesticide
use
report data: 2000, indexed by
chemical.
Pp. 341-343. www.cdpr.ca.gov.
California
data suggest that agricultural uses
of
pyrethrin are small relative to other uses.
Inert Ingredients
Like
most pesticides, commercial
pyrethrin-containing
insecticides contain
ingredients
other than pyrethrins
which,
according to U.S. pesticide law,
are
called “inert.”11 Except for
acute
toxicity
testing, all toxicology tests required
for
registration of pyrethrin
products
were conducted with pyrethrins,
not
with the combination of
ingredients
found in commercial products.
12
Most inert ingredients are not
identified
on product labels, and little
information
about them is publicly
available.
For more information about
the
hazards of some of the inert ingredients
in
pyrethrin products see
“Hazards
of Inert Ingredients,” below.
Acute poisoning
Frequency:
Pyrethrins are a common
cause
of insecticide poisonings.
When
EPA summarized calls to poison
control
centers in 1991, the agency
found
that pyrethrins, and pyrethrins
Note:
This chart does not
include
household use.
Structural
pest
control
Public
health
pest
control
Agricultural
pest
control
Other
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
16
Allergic Responses to
Pyrethrins
Pyrethrins
can trigger allergic responses
that
range from unpleasant to
life-threatening.
Skin rashes, asthma,
and
hives caused by exposure to pyrethrins
or
pyrethrum have been reported
in
medical literature since the 1920s
and
1930s.19
More
serious reports were published
in
1994 and 2000. Physicians in New
shortness
of breath five minutes
after
beginning to wash her family
dog
with a pyrethrin shampoo. Almost
immediately
she suffered heart
failure
and died after paramedics
transported
her to a hospital.20 An
year-old
girl developed a severe asthmatic
attack
when washing the family
dog
with a pyrethrin shampoo. She
died
a few hours later, despite medical
treatment.21
The
refined pyrethrins in the products
that
caused these incidents are
less
allergenic than unrefined pyrethrum22
but
still have caused these
serious
reactions.
Eye irritation
People
exposed to commercial pyrethrin
products
have reported swelling,
redness,
and burning of the eyes
following
exposure.14
Effects on the Circulatory
System
Pyrethrins
affect both sugar levels
and
oxygen-carrying ability of blood.
Researchers
from the University in
Rajasthan
(
of
pyrethrins caused gerbil
blood
sugar levels to rise between 30
and
70 percent (depending on dose).
Blood
sugar peaked an hour after treatment,
but
the increase persisted for
several
days.23 The same researchers
showed
that an injection of pyrethrins
caused
a decrease in the amount of
hemoglobin
(oxygen-carrying molecules)
in
the blood,24 as well as a
decrease
in the number of red blood
cells.25
Hemoglobin concentration remained
low
for 2–3 weeks (see Figure
4);24
the reduced number of red blood
cells
persisted for 2 days.25
Other
types of exposures with a
Figure
3
Frequency of Pyrethrin Poisonings
Sources:
insecticide
exposures reported to Poison Control Centers in 1991. Prepared by J. Blondell,
Health
Effects Division.
Pyrethrin
poisonings are more frequent than poisoning cause by any other class of
insecticide
except
the organophosphates.
20,000
15,000
10,000
5,000
0
Number
of calls to poison control centers (1991)
Organophosphates
with
the synergist piperonyl butoxide,
caused
over 9,000 incidents. Only the
organophosphate
insecticides caused
more
insecticide poisoning incidents.13
(See
Figure 3.)
Symptoms:
Some symptoms of
pyrethrin
poisoning in people, headaches
and
dizziness, are related to disruptions
of
the nervous system. For
example,
the Centers for Disease Control
compiled
reports of pyrethrin exposure
incidents
including one in
which
a cook developed these symptoms
following
installation of pyrethrin
insecticide
dispensers in the restaurant
where
he worked. A customer in the
same
restaurant developed similar
symptoms.14
The
patients also developed other
symptoms
that may not be related directly
to
pyrethrins’ effect on the nervous
system:
sore throat and difficulty
breathing.14
Physiological
mechanisms: Laboratory
tests
have demonstrated that
pyrethrins
cause several neurological
disruptions
in mammals. These may
be
the cause of the sodium channel
disruption
that results in their toxic
effects
in insects, or an additional effect.
(See
“Mode of Action,” p. 1 5.)
For
example, researchers from the University
of
and
the
(
calcium
uptake in rat brain cells.
Calcium
plays a “vital role”15 in the
nervous
system, promoting the normal
release
of transmitter chemicals
from
junctions between nerves and stabilizing
the
membrane surrounding
nerve
cells.15 Two groups of
researchers,
from
the
Medical
Center16 and the
University of
showed
that pyrethrins disrupt energy
production
in brain cells.
Pyrethrins
also affect physiological
processes
that are not related to the
nervous
system. For example, researchers
at
the Osaka City Institute of Public
Health
and Environmental Sciences
(
inhibit
mitochondria, the cellular
bodies
that convert food to usable
energy.18
Pyrethrins
Carbamates Repellants Veterinary
insecticides
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
17
longer
duration caused similar effects.
A
three-month feeding study with rats
found
pyrethrins caused a decrease in
the
amount of hemoglobin in females
at
doses at or above 170 milligrams of
pyrethrins
per kilogram of body weight
(mg/kg)
per day (the middle dose in
this
experiment). Similar effects were
found
in males at higher exposures. A
three
month inhalation study found
that
pyrethrins caused anemia at doses
at
or above 0.07 milligrams per liter of
air
in males (all but the lowest dose
in
this experiment). They also caused
anemia
in females, although at higher
exposures.26
Effects on the Kidney
A
three-month feeding study with
rats
showed that pyrethrins caused
degeneration
of tubules (small tubelike
structures)
in the kidney at doses
equal
or greater than 170 mg/kg.27
Effects on Reproduction
Pyrethrins
can disrupt successful
reproduction
in both males and females.
In
a two-month feeding study
with
dogs, the weight of the testes in
animals
exposed to pyrethrins at doses
at
or above 30 mg/kg (all but the lowest
dose
tested) was less than that of
unexposed
animals.28 In a
two-generation
feeding
study with rats, the
weight
of offspring at birth and during
nursing
was less for rats fed pyrethrins
at
doses at or above 65 mg/kg
(all
but the lowest dose tested) than
for
unexposed animals.29
Concerns
about pyrethrins’ effects
on
reproduction are heightened by
studies
of dairy cows. Following treatment
of
the cows with pyrethrins, pyrethrins
were
detected in the cows’
milk.30
This study provides support for
the
concern that exposed nursing
mothers
could pass pyrethrins on to
their
children.
Disruption of Hormone
Systems
The
impact that environmental pollutants
can
have on the normal function
of
human and animal hormone
systems
has been a significant concern
in
the last decade.31 Hormones
are
biologically active molecules that
control
all responses and functions of
A
single dose of pyrethrins (by injection) caused anemia which persisted for two
weeks.
Figure
4
Exposure to Pyrethrins Causes Anemia
Source:
Saxena, S.C. and A.K. Karel. 1974. A note on the effect of pyrethrum on
haemoglobin
concentration
of Indian desert gerbils, Meriones
hurrianae. Pyreth.
Post 12:161-162.
1
7 14 21
15
10
5
Hemoglobin
concentration(grams per 100 ml blood in male gerbils)
exposed
unexposed
Days
after treatment
Figure
5
Exposure to Pyrethrins Disrupts
Normal Hormone Functions
Source:
Eil, C. and B.C. Nisula, 1990. The binding properties of pyrethroids to human
skin
fibroblast
androgen receptors and to sex hormone binding globulin. J. Steroid Biochem.
35:
409-414.
100
50
0
100
50
0
In
experiments with human cells, pyrethrins inhibited the normal binding of sex
hormones.
Unexposed
Exposed
Inhibition of the binding
of testosterone to a
hormone-binding protein
Binding
of testosterone to sex hormone binding proteinin human blood (% of unexposed
cells)
Binding
of a synthetic hormone to androgen receptorsin human genital skin (% of
unexposed cells)
Unexposed
Exposed
Displacement of a
sex hormone from
hormone receptors
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
18
the
body. Dramatic changes in the activity
of
cells in humans and other
animals
“are caused by extremely small
amounts”
of hormones or other chemicals
that
disrupt this system.32
Pyrethrins
appear to disrupt the
normal
functioning of sex hormones.
Researchers
from Brown University and
the
National Institutes of Health
showed
that pyrethrins displace hormones
from
androgen receptors in cell
cultures
of human genital skin. Androgens
are
sex hormones that promote
development
of male sex characteristics;
testosterone
is a familiar example.
The
same researchers also
showed
that pyrethrins block the binding
of
testosterone to the a sex hormone
binding
protein in human blood.
In
both experiments pyrethrins were
more
potent than the synthetic pyrethroids
tested.33
(See Figure 5.)
Pyrethrins
also inhibit binding to
peripheral
benzodiazepine receptors,
found
in high concentration in the testes
and
thought to be involved in “steroid
metabolism
or hormonal responsiveness.”
As
in the study summarized
in
the previous paragraph, in this experiment
pyrethrins
were more potent
than
the synthetic pyrethroids tested.34
Carcinogenicity
Pyrethrins
are associated with increased
cancer
risks among farmers
and
have also caused cancer in laboratory
tests.
(See Figure 6.)
Researchers
from the National Cancer
Institute
studying risk factors for
leukemia
found that farmers exposed
to
pyrethrins used for pest control on
livestock
had an increased risk of developing
leukemia.
Exposure to pyrethrins
was
associated with a 3.7-fold
increase
in risk.35
In
1999, EPA evaluated the ability
of
pyrethrins to cause cancer. The
agency
concluded that pyrethrins
should
be classified as “likely to be a
human
carcinogen by the oral route.”
This
EPA evaluation was based on tests
which
demonstrated increases in the
frequency
of several cancers in rats.
The
incidence of liver tumors was
higher
in exposed female rats than in
unexposed
ones. Also, in both sexes,
the
incidence of thyroid tumors was
greater
in exposed rats than in unexposed
ones.36
Other
carcinogenicity studies showed
that
the incidence of lung cancers in
exposed
male mice was greater than
in
unexposed ones37 and that the
incidence
of
parathyroid tumors was
greater
in exposed rats than in unexposed
ones.38
Effect of Gender
Several
laboratory studies suggest
that
females may be more susceptible
to
pyrethrins than males. The distribution
of
pyrethrins in rats after exposure
is
highest in body fat. However,
the
concentration in female fat was
approximately
double that found in
male
fat. Also, the median oral lethal
dose
for male rats was over twice the
dose
required to kill females.39
Human Exposure
Pyrethrins
are absorbed slowly
through
the stomach, intestines, and
skin.
However, pyrethrins can be absorbed
“more
quickly through the
lungs.”40
This suggests that exposure
through
breathing droplets or airborne
particles
deserves particular attention.
Synergy
Carboxyesterases,
enzymes that
detoxify
pyrethrins, are inhibited by
organophosphate
insecticides, thus organophosphate
insecticides
increase
pyrethrins’
toxicity.10
Effects on Cats
Cats
are particularly susceptible to
pyrethrin
poisoning because their livers
inefficiently
detoxify this insecticide.
41
As a consequence, there are a
large
number of poisoning incidents.
Veterinarians
summarizing calls made
to
an animal poison control center in
1986
found that pyrethrin-related incidents
were
more numerous than incidents
involving
any other insecticide.42
Symptoms
of pyrethrin poisoning in
cats
include excessive salivation, altered
behavior,
depression, anorexia,
and
high body temperature.42
Figure
6
Exposure to Pyrethrins is Associated
with Increased Cancer
Risks in Farmers and Laboratory
Animals
Sources:
Brown,
L.M. et al. 1990. Pesticide exposures and other agricultural risk factors for
leukemia
among
men in Iowa and Minnesota. Cancer Res. 50: 6585-6591.
World
Health Organization and Food and Agricultural Organization. 2000. Pesticide
residues in
food
— 1999. [Part II] Toxicological evaluations. Geneva, Switzerland: World Health
Organization.
p. 281.
Leukemia
risk in farmers who use pyrethrins as alivestock insecticide (odds ratio)
Never
handled
pyrethrins
Handled
pyrethrins
4
3
2
1
0
Number
of thyroid tumors (in 120 rats tested)
15
10
5
0
Amount
of pyrethrins in food
(milligrams/kilogram
of body weight)
0
50 100 150
Livestock
Farmers
Laboratory
Animals
Pyrethrins
are associated with an increased leukemia risk in farmers who use them to
control
livestock
pests. They also cause an increased frequency of thyroid tumors in laboratory
studies.
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
19
Young
cats (less than four years
old,
but especially if less than one
year
old) are more susceptible to pyrethrins
than
older cats.41
Effects on Birds
In
general, relatively large amounts
of
pyrethrins are required to kill
birds.43
However effects other than
death
have been found at lower exposures.
Scientists
from the University
of
Rajasthan (India) found that doses
between
10 and 50 mg/kg of pyrethrum
caused
excitability and decreased
appetites
in pigeons.44 In sparrows,
doses
of 400 mg/kg caused excitability
and
an increase in flying, as
well
as a decrease in food consumption
and
weight. The weight of the
liver,
intestine, pancreas, kidney, and
testes
also decreased.45
Effects on Fish
Pyrethrins
are “extremely toxic to
fish,”
according to the Agency for Toxic
Substances
and Disease Registry.46 Median
lethal
concentrations (the concentration
that
kills half of a test population)
range
from 9 to 58 parts per billion. A
summary
by the U.S. Fish and Wildlife
Service
found that channel catfish and
coho
salmon were the most susceptible
species.47
Pyrethrins
are more toxic to fish in
warm
water than in cold water.47
Effects on Other Aquatic
Animals
Aquatic
animals other than fish are
also
killed by low concentrations of
pyrethrins.
The most susceptible larval
stage
of the American lobster is
killed
by concentrations of 1 part per
billion.48
The scud (a fresh water crustacean)
is
killed by concentrations of
12
parts per billion.49
Effects on Honey Bees
Pyrethrins
are “highly toxic” to bees;
0.02
micrograms is sufficient to kill a
bee.50
Toxicity of commercial pyrethrin
products
to bees was demonstrated by
an
entomologist at Auburn University
who
showed that a commercial pyrethrin
insecticide
caused 100 percent
“knockdown,”
the inability of the bee
to
walk or fly. Some of the inert ingredients
used
in pyrethrin products
appear
to increase knockdown
potency.51
Effects on Other Beneficial
Insects and Spiders
It
is not surprising that pyrethrins,
because
they are insecticides, are toxic
to
agriculturally useful insects and spiders.
The
International Organization for
Biological
Control found that a commercial
pyrethrin
product killed over
99
percent of two parasitoid wasps
and
a predatory fly. (Parasitoids are
insects
which develop in and kill the
eggs
or larvae of another species.) This
study
also found pyrethrins caused 80
percent
mortality of two other parasitoid
species,
a fly and a wasp.52 Cornell
University
Agricultural Experiment Station
researchers
found that pyrethrins
killed
four common species of wasp
that
are parasitoids of house and stable
flies
in dairies.53 The
web-building spider
Argiope argentata is also
susceptible
to
pyrethrins; two commercial
pyrethrin
products caused more than
50
percent mortality of this spider in a
test
conducted at the University of
Regensburg
(Germany).54
Development of Resistance in
Pest Insects
At
least fifteen species of insects,
including
lice, cockroaches, weevils,
bedbugs,
house flies, mosquitos, meal
moths,
and aphids have developed
pyrethrin
resistance, the ability to survive
treatment.
Resistance ratios (the
ratio
between the amount needed to
kill
a resistant individual and the
amount
needed to kill a susceptible
individual)
are often relatively low, but
in
four species resistance ratios are
above
100. The four species are the
German
cockroach, the granary weevil,
and
two house flies.55
Repeated
exposure to synthetic
pyrethroids
can cause the development
of
resistance to pyrethrins.55
Persistence
Outdoors,
pyrethrins persist only for
a
short time. For example, after application
of
pyrethrins to bare soil, the
half
life (the time required for half of
the
applied pyrethrin to break down
or
move away from the application
site)
was two hours or less.56
Pyrethrins
persist much longer indoors
than
they do outdoors. Studies
conducted
at the University of Ulm and
the
Fraunhofer Institute of Toxicology
and
Aerosol Research (Germany) found
that
pyrethrins persisted 60 hours after
treatment
on horizontal surfaces,57
two
weeks after treatment on airborne
particles,
and over two months in carpet
dust.58
(See Figure 7.)
Effects on Soil Fertility
Insecticides
are generally not expected
to
have impacts on plants.
However,
they can indirectly affect
plant
growth if they change the growth
or
abundance of soil microorganisms
that
are important in the maintenance
of
soil fertility. Scientists at the University
of
Ibadan (Nigeria) showed that
treatment
of agricultural soils with
pyrethrin
caused an increase in the
abundance
of soil bacteria and a decrease
in
the abundance of soil fungi.
In
addition, the number of these species
was
less in treated soil than in
Figure
7
Persistence of Pyrethrins
after Treatment
Persistence
after treatment (in days)
75
50
25
0
On
airborne
particles
In
carpet
dust
Source:
Berger-Preiß, E., K. Levssen, and
A.
Preiß. 1997. Analysis of individual
natural
pyrethrins in indoor matrices by
HRG/ECD.
J. High Resol. Chromatogr.
20:
284-289.
Pyrethrins
persisted in carpet dust for over
two
months after treatment.
NORTHWEST COALITION FOR ALTERNATIVES
TO PESTICIDES/NCAP
P.
O. B O X 1 3 9 3, E U G E N E, O R E G O N 9 7 4 4 0 / ( 5 4 1 ) 3 4 4 - 5 0 4
4
JOURNAL OF PESTICIDE REFORM/ SPRING
2002 • VOL. 22, NO. 1
20
untreated
soil. The end result was a
reduction
in the amount of the important
soil
nutrient nitrogen.59 Another
study,
from the Central Rice Institute
(India),
showed that pyrethrin treatment
of
rice fields reduced the nitrogen-
fixing
ability of the soils as much
as
80 percent.60 Nitrogen
fixation is
the
conversion (mostly by bacteria) of
atmospheric
nitrogen into a form that
is
usable by plants.61
References
1.
Dept. of Health and Human Services. Public Health
Service.
Agency for Toxic Substances and Disease
Registry.
2001. Toxicological profile for
pyrethrins
and pyrethroids. Draft. p.147-150.
2.
McCord, C.P., C.H. Kilker, and D.K. Minster.
1921.
Pyrethrum dermatitis. JAMA
77(6): 448-449.
3.
Whitmore, R.W., J.E. Kelly, and P.L. Reading.
1992.
National home and garden pesticide use
survey.
Final report, vol. 1: Executive summary,
results,
and recommendations. Research Triangle
Park
NC: Research Triangle Institute. Table G-1.
4.
Casida, J.F. and G.B. Quistad. 1995. Metabolism
and
synergism of pyrethrins. In Pyrethrum
flowers: production, chemistry,
toxicology, and
uses, ed. J.E. Casida
and G.B. Quistad. New
York
NY: Oxford University Press. Pp. 259-276.
5.
Ware, G.W. 2000. The
pesticide book. Fresno
CA:
Thomson Publications. Pp. 65-66.
6.
Crosby, D.G. 1995. Environmental fate of pyrethrins.
In
Pyrethrum flowers:
production, chemistry,
toxicology, and uses,
ed. J.E. Casida and
G.B.
Quistad. New York NY: Oxford University
Press.
Pp. 194-213.
7.
Calif. Environmental Protection Agency. Dept.
of
Pesticide Regulation. 2001. Summary of pesticide
use
report data: 2000, indexed by chemical.
Pp.
341-343. www.cdpr.ca.gov.
8.
Ref. # 6, pp. 177-178.
9.
Ref. # 1, p. 88.
10.
Ray, D.E. and P.J. Forshaw. 2000. Pyrethroid
insecticides:
Poisoning syndromes, synergies,
and
therapies. Clin.
Toxicol. 38:95-101.
11.
Federal Insecticide, Fungicide, and Rodenticide
Act
Sec. 2(m).
12.
40 Code of Federal
Regulations § 158.340.
13.
U.S. EPA. Office of Pesticides and Toxic Substances.
Undated
memo. Human insecticide exposures
reported
to poison control centers in 1991.
Prepared
by J. Blondell, Health Effects Div.
14.
Shafey, O., L. Mehler, and L. Baum. 2000. Illnesses
associated
with use of automatic insecticide
dispenser
units—selected states and United
States,
1986–1999. MMWR 49(22):
492-495.
15.
Ramadan, A.A. et al. 1988. Action of pyrethroids
on
K+-stimulated calcium uptake by, and
[3H]nimodipine
binding to, rat brain synaptosomes.
Pest. Biochem. Physiol. 32:114-122.
16.
Prasada Rao, K.S., C.S. Chetty, and D. Desaiah.
1984.
In vitro effects of pyrethroids on rat brain
and
liver ATPase activities. J.
Toxicol. Environ.
Health 14: 257-265.
17.
Kakko, I., T. Toimela, and H. Tähti. 2000. Piperonyl
butoxide
potentiates the synaptosome
ATPase
inhibiting effect of pyrethrin. Chemosphere
40:
301-305.
18.
Yamano, T. and S. Morita. 1993. Effects of pesticides
on
isolated rat hepatocytes, mitochondria,
and
microsomes. Arch.
Environ. Contam.
Toxicol. 25:
271-278.
19.
Adams, R.M. 1983. Occupational
skin disease.
New
York: Grune & Stratton. p. 362.
20.
Wax, P.M. and R.S. Hoffman. 1994. Fatality associated
with
inhalation of a pyrethrin shampoo.
Clin. Toxicol. 32:
457-460.
21.
Wagner, S.L. 2000. Fatal asthma in a child after
use
of an animal shampoo containing pyrethrin.
West J. Med. 173:86-87.
22.
Zucker, A. 1965. Investigation of purified pyrethrum
extracts.
Ann. Aller. 23:
335-339.
23.
Karel, A.K. and S.C. Saxena. 1975. Investigation
on
the acute toxic effect of pyrethrum on
the
blood glucose and of glucose administration
on
the acute pyrethrum toxicity in Meriones
hurrianae Jerdon
(Rodentia). Arch.
Intern.
Physiol. Biochim.
83: 19-25.
24.
Saxena, S.C. and A.K. Karel. 1974. A note on
the
effect of pyrethrum on haemoglobin concentration
of
Indian desert gerbils, Meriones
hurrianae. Pyreth. Post 12:161-162.
25.
Karel, A.K. and S.C. Saxena. 1975. Investigations
on
the acute toxic effect of pyrethrum on various
haemotological
aspects of Meriones
hurrianae Jerdon,
the
Indian desert gerbil. Pyreth.
Post 13: 61-67.
26.
World Health Organization and Food and Agricultural
Organization.
2000. Pesticide residues
in
food—1999. [Part II] Toxicological evaluations.
Geneva,
Switzerland: World Health Organization.
Pp.
277-278.
27.
Schoenig, G.P. 1995. Mammalian toxicology of
pyrethrum
extract. In Pyrethrum
flowers: production,
chemistry, toxicology, and uses,
ed. J.E.
Casida
and G.B. Quistad. New York NY: Oxford
University
Press. Pp. 249-257.
28.
Ref. # 26, p. 279.
29.
U.S. EPA. Office of Pesticides and Toxic Substances.
1991.
Pyrethrum extract (technical).
Evaluation
of a two-generation rat reproduction
study
to support reregistration of pyrethrum extract.
Memo
from L.J. Hansen to L. DeLuise.
30.
World Health Organization and Food and Agriculture
Organization
of the United Nations. 2000.
Pesticide
residues in food—2000. FAO Plant
Production
and Protection Paper 163. p. 114.
31.
National Research Council. Commission on Life
Sciences.
Board on Environmental Studies and
Toxicology.
1999. Hormonally active
agents in the
environment. Washington,
D.C.: National Academy
Press,
p. 10.
32.
Eubanks, M.W. 1997. Hormones and health.
Environ. Health Persp. 105:
482-487.
33.
Eil, C. and B.C. Nisula, 1990. The binding properties
of
pyrethroids to human skin fibroblast
androgen
receptors and to sex hormone binding
globulin.
J. Steroid Biochem.
35: 409-414.
34.
Ramadan, A.A. et al. 1988. Actions of pyrethroids
on
the peripheral benzodiazepine receptor. Pest.
Biochem. Physiol.
32: 106-113.
35.
Brown, L.M. et al. 1990. Pesticide exposures
and
other agricultural risk factors for leukemia
among
men in Iowa and Minnesota. Cancer Res.
50:
6585-6591.
36.
U.S. EPA. Office of Pesticide Programs. Health
Effects
Division. Cancer Assessment Review
Committee.
1999. Cancer Assessment Document:
Evaluation
of the carcinogenic potential of pyrethrins.
Executive
summary. Washington, D.C.
37.
Ref. # 26, p. 280.
38.
Hurley, P.M., R.N. Hill, and R.J. Whiting. 1998.
Mode
of carcinogenic action of pesticides inducing
thyroid
follicular cell tumors in rodents.
Environ. Health Persp. 106:
437-445.
39.
Ref. # 26, p. 274-275.
40.
Extension Toxicology Network. 2001. Pesticide
information
profile: Pyrethrins. http://
pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-
ziram/pyrethrins-ext.html.
41.
Campbell, A. and M. Chapman. 2000. Handbook
of poisoning in dogs and cats.
Malden MA:
Blackwell
Science. p. 43.
42.
Beasley, V.R. and H.L. Trammel. 1989. Incidence
of
poisonings in small animals. Curr. Vet.
Ther. 10: 97-113.
43.
Hudson, R. H., R.K. Tucker, and M.A. Haegele.
1984.
Handbook of toxicity of pesticides to wildlife.
Second
edition. Washington, D.C.: U.S. Dept.
of
the Interior. Fish and Wildlife Service. p. 68.
44.
Saxena, S.C. and P.P. Bakre. 1978. Toxicity of
pyrethrum
to Blue Rock pigeon. Pyreth.
Post
14:
47-48.
45.
Saxena, P. and Saxena, S.C. 1973. Effect of
pyrethrum
on body and organ weights, food
consumption
and faeces production of the house
sparrow,
Passer domesticus. Pyreth. Post 12:
76.
46.
Ref. # 1, p. 159.
47.
Johnson, W.W. and M.T. FInley. 1980. Handbook
of
acute toxicity of chemicals to fish and
aquatic
invertebrates. Washington, D.C.: U.S. Dept.
of
the Interior. Fish and Wildlife Service. p. 70.
48.
Burridge, L.E and K. Haya. 1997. Lethality of
pyrethrins
to larvae and postlarvae of the American
lobster
( Homarus americanus).
Ecotoxicol.
Environ. Safety 38:
150-154.
49.
Sanders, H.O. 1969. Toxicity of pesticides to
the
crustacean Gammarus
lacustris. Technical
Paper
No. 25.
the
Interior. Fish and Wildlife Service. Bureau of
Sport
Fisheries and Wildlife.
50.
Gabriel, K.L. and R. Mark. 1995. Environmental
toxicology
of pyrethrum extract. In Pyrethrum
flowers: production, chemistry,
toxicology, and
uses, ed. J.E. Casida
and G.B. Quistad. New
51.
Appel, A. G. 1990. Knockdown efficiency and
materials’
compatibility of wasp and hornet spray
formulations
to honey bees (Hymenoptera:
Apidae).
J. Econ. Entomol.
83: 1925-1931.
52.
joint
pesticide testing programme by the IOBC/
WPRS-working
group “Pesticides and Beneficial
Arthropods.”
Z. ang. Ent. 95:
151-158.
53.
Rutz, D.A. and J.G. Scott. 1990. Susceptibility
of
muscoid fly parasitoids to insecticides used
in
dairy facilities. In Biocontrol
of arthropods affecting
livestock and poultry,
ed. D.A. Rutz and
R.S.
Patterson.
Pp.
247-263.
54.
Mansour, F. and W. Nentwig. 1988. Effects of
agrichemical
residues on four spider taxa: laboratory
methods
for pesticide tests with web-building
spiders.
Phytoparasitica 16:
317-325.
55.
Cochran, D.G. 1995. Insect resistance to pyrethrins
and
pyrethroids. In Pyrethrum
flowers: production,
chemistry, toxicology, and uses,
ed. J.E.
Casida
and G.B. Quistad.
University
Press. Pp. 234-248.
56.
World Health Organization and Food and Agriculture
Organization
of the United Nations. 2000.
Pesticide
residues in food—2000. Evaluations
Part
1—Residues. FAO Plant Production and
Protection
Paper 165. p. 700.
57.
Class, J.T. and J. Kintrup. 1991. Pyrethroids as
household
insecticides: analysis, indoor exposure
and
persistence. Fresenius
J. Anal. Chem.
340:
446-453.
58.
Berger-Preiß, E., K. Levssen, and A. Preiß. 1997.
Analysis
of individual natural pyrethrins in indoor
matrices
by HRG/ECD. J. High
Resol.
Chromatogr.
20: 284-289.
59.
Taiwo, L.B. and B.A. Oso. 1997. The influence
of
some pesticides on soil microbial flora in relation
to
changes in nutrient level, rock phosphate
solubilization
and P release under laboratory conditions.
Agric. Ecosys. Environ.
65: 59-68.
60.
Nayak, D.N., I.C. Pasalu, and V.R. Rao. 1980.
Influence
of natural and synthetic insecticides
on
nitrogen fixation (C2H2 reduction)
in the rice
rhizosphere.
Curr. Sci. 49:
118-119.
61.
BioTech Resources and
1995-8.
BioTech life science dictionary. http://
biotech.icmb.utexas.edu/search/dict-search.html.
This appendix copied from:
http://www.pesticide.org/PyrethrinsPyrethrum.pdf