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Research into Permethrin and Carbaryl

This page presents research into the pesticides Permethrin and Carbaryl by RMEHA member Chris.

In the interest of education and information sharing, below is the data I've gathered about Permethrin and Carbaryl. I include Carbaryl because it is what the USFS is using on trees in campgrounds and on six acres (hundreds of trees) of public land at Eldora Ski area (per my conversation with Mark Martin at the CWPP meeting). In addition, Rocky Mountain National Park also uses Carbaryl on high-value trees (~1,000).

The more one digs into the literature, the more a few issues emerge:

1. _Pesticides may act synergistically over time in the environment or in the human body:_

a. four different pyrethroids and DDT were found in breast milk in women in a certain area of South Africa. Why didn't these women detox these pesticides more quickly? How do they interact in the body? How do they affect newborns?

b. In newborns, the Environmental Working Group found industrial chemicals, pollutants and pesticides in umbilical cord blood (/Environmental Working Group, July 14, 2005/) “researchers at two major laboratories found an average of 200 industrial chemicals and pollutants in umbilical cord blood from 10 babies born in August and September of 2004 in U.S. hospitals. Tests revealed a total of 287 chemicals in the group. The umbilical cord blood of these 10 children, collected by Red Cross after the cord was cut, harbored pesticides, consumer product ingredients, and wastes from burning coal, gasoline, and garbage

c. Chemically induced diseases (Gulf War Syndrome): “Combinations of two or three pesticides, which are commonly found in the environment at low levels, are up to 1600 times more powerful than any of the pesticides individually in their impact on hormones…Doctors believe this _brain damage_ to have been caused by exposure to combinations of low level nerve gas, anti-nerve gas tablets and DEET contained in insect pesticides and repellents. Magnetic Resonance Imaging has identified specific abnormalities in the basal ganglia that impact cognitive skills, including memory, sense of direction, inability to understand instructions and decision-making, often resulting in depression.”

See also: Environmental Toxicology and Chemistry, SYNERGISTIC TOXICITY OF ATRAZINE AND ORGANOPHOSPHATE INSECTICIDES CONTRAVENES THE RESPONSE ADDITION MIXTURE MODEL, Pamela A. Pape-Lindstrom and Michael J. Lydy, Department of Biological Sciences, 1845 N. Fairmount, Wichita State University, Wichita, Kansas 67260-0026, USA

2. _Even low-dose exposures to permethrin and carbaryl are known to cause harm_ (see below)

3. _Regulations change over time, in many cases they increase_, as more information becomes available. Companies don't have to prove that these are safe; rather, the EPA and other entities have to prove harm before stricter regulations are passed.

4. _Not all people process pesticides in the same way._ Therefore, though 10 people might not get sick, one neighbor or their child or pet might.

5. _The short summaries on Permethrin and Carbaryl provided by most public agencies are inadequate_ for educating the public about the complex immediate and long-term effects of these pesticides.

We all deserve to know the full extent of the research on products before we use them or are exposed to them, especially in the case of children who have no choice in the matter. I have added enough citation information so all points can be verified.



--kills beneficial insects such as bees and other pollinators (Extoxnet, 1993); also kills insects that prey on mountain pine beetles (such as certain wasps, flies, and beetles)

--toxic to fish (Extoxnet, 1993)

--bioconcentrates in fish (Journal of Pesticide Reform, 1998)

--Cats are exquisitely susceptible to the toxic effects of ##permethrin##. Symptoms: “Drooling, Lethargy, Muscle tremors, Vomiting, Seizures” (

, among many other pet and veterinarian sites)

--Cats: "The severity of permethrin toxicity varies with each individual. Some cats develop signs when only "one drop" is applied, while others show no clinical signs after an entire vial is used." (Small animal toxicosis--insecticides, ASPCA Animal Poison Control Center)

--toxic to wildlife: "should not be applied or allowed to drift to crops or weeds in which active foraging takes place" by wildlife (Extoxnet, 1993; ICI Americans Inc. 1985)

--it's a _restricted use pesticide_ because of adverse effects to aquatic organisms as a result of spray drift and runoff (EPA's Permethrin Facts RED, 2006)


--suspected of having carcinogenic effects (Extoxnet, 1993)

--EPA classified permethrin as "likely to be carcinogenic to humans" by the oral route based on two reproducible benign tumor types (lung and liver) in mice (EPA Permethrin Facts; Reregistration Eligibility Decision (RED) Fact Sheet, 2006)

--suspected endocrine disruptor ##even at low doses ##(Colborn et al. 1993; U.S. EPA 1997)

--suspected of causing enlargement of the liver and destruction of the lining of nerve tracts (Extoxnet, 1993)

--permethrin, cyfluthrin, cypermethrin, and deltamethrin (and DDT) have been detected in human breast milk in women living in an area of South Africa in which pyrethroids were used for malaria control. (Bouwman H, Sereda B, Meinhardt H. 2006. Simultaneous presence of DDT and pyrethroid residues in human breast milk from a malaria endemic area in South Africa. Environ Pollut 144:902–917).

--aggregate short-term non-cancer risk estimates ##exceeded ##level of concern (LOC) for toddlers and adults through post-application exposure from high-contact activities on lawns and (indoors) on carpets (EPA's RED, 2006)—##no long-term aggregate risk was assessed##

--German studies link exposure to permethrin and phenothrin with leukemia, lymphoid cancer and multiple chemical sensitivity. (##Household spray cancer link, Pesticides News 28, June 1995.)######


--_Virginia Tech researchers (2003) found ##low-dose effects ##of permethrin on those brain pathways involved in Parkinson's Disease_ (Study of Insecticide Neurotoxicity Yields Clues to Onset of Parkinson's Disease, Blacksburg, VA, 2003)

-- individuals with defects in sulfate-related enzymes may be unable to break down permethrin, which likely leads to motor neuron disease (Pall et a. 1987, Motorneuron Disease as manifestation of pesticide toxicity, The Lancet, Sept. 19: 685; Steventon et al., 1990, Pesticide activity and motor neuron disease, J. Neurol., Neurosurg Psych. 53(7): 621-622).


*--*embryo loss in pregnant rabbits and rats (EPA, Office of Pesticide Programs. Health Effects Division. 1997. Tox oneliners: Permethrin. Washington D.C., June 24; Spencer, F. and Z. Berhane. 1982. Uterine and fetal characteristics in rats following a post-implantational exposure to permethrin. Bull. Environ. Contam. Toxicol. 29:84-88)

--testosterone and sperm counts were dramatically reduced in tests on mice; "While the doses used in this study were high, the effects on testosterone levels, StAR gene expression and sperm count were profound. The authors state that "the dose of human occupational exposure was roughly estimated to be 0.12 mg/kg (unpublished data) about 100 times lower levels than the exposed mice on a weight basis." Importantly, all of the doses tested resulted in decreased testosterone and sperm count.

_It is very likely that lower exposure levels would have similar, but perhaps less dramatic, negative effects."_ (Zhang, S-Y, Y Ito, O Yamanoshita, Y Yanagiba, M Kobayashi, K Taya, C-M Li, A Okamura, M Miyata, J Ueyama, C-H Lee, M Kamijima and T Nakajima. Permethrin may disrupt testosterone biosynthesis via mitochondrial membrane damage of leydig cells in adult male mouse. *Endocrinology, in press (article in Environmental Health News, 2007)*

--Pyrethroid: Delayed female puberty: "This is the first study to show an inhibitory action of a type II pyrethroid pesticide, ESF, on the hypothalamic control of prepubertal gonadotropin secretion. This study is also the first to show that short-term administration of ESF to juvenile animals significantly delays the onset of female puberty." (The Pyrethroid Pesticide Esfenvalerate Suppresses the Afternoon Rise of Luteinizing Hormone and Delays Puberty in Female Rats, Michell D. Pine, Jill K. Hiney, Doyeon Lee, and W. Les Dees, Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas,## Environmental Health Perspectives##, 2008)*


--skin##eye irritant, numbness##prickling on skin, headache##dizziness##nausea##vomiting##fatigue, fluid in lungs


--has a half-life of 30 days in the soil (Wauchope et al., Reviews of Environmental Contamination and Toxicology, 123:1-156, 1992)



--Carbaryl is highly toxic to beneficial insects (EPA IRED Fact Sheet on Carbaryl, 2003)

--Carbaryl is moderately toxic to aquatic organisms, such as rainbow and lake trout, bluegill, and cutthroat (Extoxnet, Carbaryl, 1993)

--Carbaryl is highly toxic to aquatic invertebrates (EPA IRED Fact Sheet on Carbaryl, 2003)

--The Environmental Fate and Effects Division, EPA, found high risks for mammals from carbaryl application, particularly for small and medium-sized mammals. For large size mammals, the findings included acute restricted use, and that endangered species level of concern are exceeded following ##application on trees. ##(Pete Harrison, Forestry and Public Lands Program Associate, Eureka, California; EFED, EPA)

--Cats and dogs: exposure can cause behavioral changes, excessive tearing and salivation, muscle tremors, twitching, vomiting, and diarrhea (http://www.peteducation.com/article.cfm?c=2+1940&aid=2250) upon exposure to Carbaryl. Severe intoxications can result in paralysis and death. Birth defects have been seen in studies on Beagles (Smalley, H.E., Curtis, J.M. and Earl, F.L. Teratogenic action of carbaryl in beagle dogs. Toxicol. Appl. Pharmacol., 13: 392 (1968)).


##-- Carbaryl is banned in Austria, Sweden, Germany, and Angola because of danger to human health and environment


--Carbaryl has been declared a likely carcinogen by both the US EPA (##Carbaryl RED, Amended, 2008 <

and the UK Government Committee on Carcinogenicity (Nov. 1995;

--Non-Hodgkin's Lymphoma: two recent studies have found an association between use of carbaryl by farmers and an increased risk of the cancer non-Hodgkin's lymphoma (NHL)-- researchers from Yale University, the National Cancer Institute, and the University of Nebraska, found that farmers in four Midwestern states who used carbamate pesticides “had a 30% to 50% increased risk of NHL.” The most consistent association was for farmers who used the carbaryl-containing insecticide ##Sevin## (Zheng, T. et al. 2001. Agricultural exposure to carbamate pesticides and risk of non-Hodgkin lymphoma. J. Occup. Environ. Med. 43:641-649; McDuffie, H.H. 2001. Non-Hodgkin's lymphoma and specific pesticide exposures in men: Cross-Canada study of pesticides and health. Cancer Epidemiol. Bio. Prev. 10:1155-1163)


--Carbaryl can cause infertility and pregnancy loss in ##both pesticide applicators as well as those exposed in daily life####, ##according to researchers from the Institute of Toxicology in Nanjing, China, and the UCLA School of Public Health (2004).


--Carbaryl is exposure is associated with asthma (Eskanazi, B, A Bradman, and R Castorina. 1999. Exposures of children to pesticides and their potential adverse health effects. Environmental Health Perspectives 107(Suppl 3): 409-419


--nonspecific symptoms raise the question of whether chronic carbaryl neurotoxicity might be occurring more frequently than previously suspected (“Subacute neurotoxicity following long-term exposure to carbaryl”; R. A. Branch M.D. and E. Jacqz M.D., Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee)


Carbaryl, a widely used insecticide, is reputed to have a wide safety margin. It can induce acute cholinesterase poisoning, which is rapidly reversible on discontinuation of exposure. Long-term sequelae from long-term exposure have not previously been described in humans. This report describes the experience of a 75-year-old man who had long-term excessive exposure to carbaryl and in whom a debilitating syndrome, including headaches, memory loss, proximal muscle weakness, muscle fasciculation, muscle cramps, and anorexia with marked weight loss, developed. At the time of diagnosis, serum pseudocholinesterase levels were low, and his major symptoms resolved on termination of exposure. Late clinical features were sleep apnea and progressive development of a peripheral neuropathy. The difficulty in diagnosing the cause of a group of relatively nonspecific symptoms raises the question of whether chronic carbaryl neurotoxicity might be occurring more frequently than previously suspected.


--Carbaryl is a danger to firefighters and others near burning trees that have been sprayed with carbaryl, according to International Programme On Chemical Safety (IPCS). Fumes from carbaryl decomposition products are highly toxic. (Extoxnet Research, 1996; Material Safety Data Sheet for Carbaryl, Loveland Products, Inc.)

--IPCS warns that if carbaryl is involved in a major fire or in a fire involving other products, advise the fire service that protective clothing and breathing apparatus should be worn, because toxic decomposition products, such as nitrogen oxides, methylamine, and carbon monoxide may be formed. (IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY Health and Safety Guide No. 78)


--Silverthorne##Dillon found it in their water supply (i.e., in treated water) (


--Carbaryl is detected in groundwater in Alabama, California, Colorado, Indiana, New Jersey, Penn., Texas, Virginia, and Washington (USGS, 2007)

--Carbaryl degrades quickly in neutral and alkaline waters (2.5 - 10.5 days), but it can last up to 1,500 days at pH 5 and 27 degrees C, (75 degrees Fahrenheit) according to Health Canada's report on carbaryl

--Carbaryl is the second most widely detected insecticide in surface water (Martin et al. 2003, National Water Quality Assessment Program)


##--##Symptoms from Carbaryl exposure: shortness of breath, respiratory irritation, eye inflammation, nausea, stomach cramps, diarrhea, restlessness, twitching, and##or convulsions


--the half-life of Carbaryl in soil is 7-29 days depending on soil type (Extoxnet, 1996)


##----since 2003, approximately 35 % of the residential use carbaryl products have been canceled and many new rules for use were put into place (EPA RED for Carbaryl 2007)##

##--NRDC and the Washington Toxics Coalition petitioned EPA to cancel carbaryl and revoke all tolerances due to its unreasonable risks on the environment (2005)##

##--In 2006, the EPA canceled liquid broadcast use of carbaryl on residential grass (EPA RED for Carbaryl 2007)##

##--in 2008, close to four years after NRDC's petition, the EPA denied the petition to cancel carbaryl and revoke all tolerances##

##--in 2008, the following application methods were prohibited: hand, spoon, shaker can, backpack spreaders (front and back mounted), power backpack sprayers, tree injects, and ALL handheld foggers (Carbaryl RED (EPA), Amended, 2008)##



--_Ontario (Canada) Physicians Report (2004): Recommend reduction of pesticide risk and use wherever possible_*;* *Comprehensive Review of Pesticide Research Confirms Dangers: ##Family doctors highlight link between pesticide exposure and serious illnesses and disease; children particularly vulnerable.##*

Carbaryl is consistently link to serious illnesses such as cancer, reproductive problems and neurological diseases; children are particularly vulnerable—blood cancers, brain cancer, acute leukemia (


--_Inert ingredients_ make up the bulk of the liquid in a product. Trade Secret laws prevent the disclosure of these ingredients. Question of their health and environmental effects.


--_Not all humans detox pesticides equally_: Permethrin and three other pyrethroids showed up in human breast milk in a study in South Africa (see above study)

-- individuals with defects in sulfate-related enzymes may be unable to break down permethrin, which likely leads to motor neuron disease (Pall et k. 1987, Motorneuron Disease as manifestation of pesticide toxicity, The Lancet, Sept. 19: 685; Steventon et al., 1990, Pesticide activity and motor neuron disease, J. Neurol., Neurosurg Psych. 53(7): 621-622)

--##Genetic Link May Tie Together Pesticides, ADHD, Gulf War syndrome and Other Disorders## (March 17, 2003)

Dr. Carrolee Barlow, who led the work at the Salk Institute and is now at Merck and Co., Inc., and her team, headed by Christopher Winrow, found in mice that organophosphate exposure inhibited the activity of a gene called neuropathy target esterase, or NTE. This inhibition either killed the mice before birth, or over time led to a range of behaviors very similar to ADHD. Some of the neurological problems also echoed many of the symptoms seen in Gulf War syndrome.


--_Insect immunity_: over time: some insects have developed immunity to specific pesticides within a few years


--_Bee Colony Collapse_: 1/3 of bee colonies across America have disappeared or died; bee hives contain 70+ pesticides (2008 test by Penn State Univ. researchers)


--Of the 305 severely chemically sensitive people surveyed by Dr. Pamela Reed Gibson, the _most commonly cited exposure said to initiate chemical sensitivity was pesticide_ (35 individuals).

In some cases: one-time exposure.


--Banff NP in Canada is not using pesticide spray against beetles because of ecological impacts; they are using verbonene packets, doing controlled burns, thinning, and cutting hot trees

Additional Information -

*Beyond Pesticides##NCAMP* and their: " What To Do In A Pesticide Emergency"

*"What's In a Pesticide?"*


*Californians for Pesticide Reform (CPR)*

*Canaries - NO ACCEPTABLE RISK - Campaign*

*East Bay Pesticide Alert*

*Environmental Health Network (EHN)*

*Get Set, Inc.* (AKA, Get IPM)

*No Spray Action Network*

*Pesticide Action Network North America (PANNA)*

And last but not least, please make easily available California's own: *Pesticide Illness Reporting Form* - PDF format

Follow the links below to learn more about RMEHA and Environmental Illness.

Revised '10-Jun-2009,10:33:28'