Information compiled by
Richard W. Pressinger (M.Ed.)
Wayne Sinclair (M.D.)

The following research was located from the University of Florida Medical Library regarding environmental and public health effects found to occur from exposure to the mosquito control pesticides - dibrom (naled) - permethrin - and other chemical ingredients found in dibrom which include - dichlorvos and trichlorfon.  As you'll read below, the evidence clearly shows these chemicals are far more harmful than previously believed and emphasizes the critical importance for implementing immediate alternatives.

Background on Brevard's Mosquito Pesticides

Brevard County Mosquito Control is currently using the pesticide "permethrin" in its "mosquito truck" spray program along with the use of the  pesticide "dibrom" (naled) in its aerial spray program.  The potential health and environmental effects outlined below strongly support the importance of finding alternatives to these pesticides as soon as possible.

Chromosome/Genetic Damage Evident in
Immune System Cells from Permethrin

SOURCE: Teratogenesis, Carcinogenesis, and Mutagenesis, 14:31-38, 1994

Researchers at the National Center of  Sanidid Ambiental in Madrid Spain found that the pesticide permethrin (the type used in Brevard's Mosquito Truck Spray Program) was able to induce "structural chromosome aberrations" in human immune system cells as well as in the reproductive cells in laboratory animals.  The chromosome damage became apparent after 2 hours of exposure at levels of 150-200 ug/ml (micrograms per milliliter).  Chromosome damage was also detected at lower levels.

As stated by the researchers:

"The effect of permethrin seemed to be dose-dependent.   Permethrin induced chromosome and chromatid-type aberrations.  The highest frequency of chromosome aberrations, mainly chromosome-type, was induced by 100 ug/ml of permethrin in both cultures... Thus, we can say that permethrin is a clear clastogenic (genotoxic) agent in two different cell systems."

J. Muro, A. Martinez, A. Lopez, M. Diaz and R. Fernandez

Helicopter Application Pesticide Dibrom
Contains Carcinogenic Chemical

SOURCE: Japanese Journal of Cancer Research, 82:157-164, February, 1991

Dichlorvos is an organophosphate pesticide that sometimes goes by the name DDVP.  It's chemical name is dichlorovinyl dimethyl phosphoric acid ester.   Concerns regarding the use of the pesticide Dibrom (naled) in Brevard's mosquito helicopter spray program are warranted as Dichlorvos is found as an ingredient in their primary mosquito control pesticide Dibrom.

Researchers at the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina studied the effects of the pesticide Dichlorvos on several types of laboratory animals.  Dichlorvos was administered beginning at levels far below that needed to kill 50% of the animals (called LD-50).  Levels administered ranged from 4 to 40 mg/kg (milligrams per kilogram) body weight.  The study itself was  carried out for 103 weeks. 

While there were no changes seen in test animals exposed to the pesticide when compared to animals not exposed to the pesticide (controls) regarding body weights and survival rates, there were other serious health effects observed.   The researchers did find significantly higher cancer rates affecting the pancreas - forestomach - as well as mononuclear cell leukemia in male rats.

The so-called "safety" of dichlorvos may have been based on articles appearing in the journal Mutation Research in which scientists were reported to "down-play" the cancer risk.  However, as stated by the scientists in this more recent research paper (pg.158):

"Different views on the carcinogenicity data have been published; most indicate that the earlier studies were inadequate (2 references pg.158) flawed (1 reference pg.158) or showed unequivocal carcinogenicity (2 references pg.158).  According to the EPA (using all the available data) "dichlorvos has been classified as a carcinogen based on oncogenic effects in mice and rats (1 reference pg.158)...... Increased incidences of mononuclear cell leukemia was observed in dosed male and female rats.  In the male rats the increase in incidence was dose-related and statistically significant.  Incidences of multiple fibroademonmas were seen in 9 exposed female rats whereas none were observed in the controls.

In conclusion the researchers stated,

"Dichlorvos caused or was associated with neoplastic responses in rats (pancreas, hematopoietic system, and possibly the mammary gland) and in mice (forestomach)."

As thousands of gallons of this chemical have been sprayed over populated areas in the Brevard community and into the Indian River - the potential for irreversible damage to public health, wildlife and marine life must be considered in light of the above research.

Po C. Chan, James Huff, Joseph K. Haseman, Roger Alison and J. D. Prejean
National Institute of Environmental Health Sciences, Research Triangle Park, NC
Southern Research Institute, Birmingham, AL

Elevated Brain Damage Found from
Mosquito Control Pesticide

Source: Neurochemical Research, 19(5),569-574, 1994

nerve damage - naled pesticideWhen the pesticide NALED is applied for mosquito control, it breaks-down in the presence of sunlight and oxygen to form a new and highly toxic chemcal known as dichlorvos.

In this current study, the chemical dichlorvos was found to cause a "severe reduction" in brain weight and shape.   The timing of exposure to the developing offspring appeared to be the key factor in determining neurological damage (known as the "critical brain growth period").  It occurred when the chemical was administered between 40-50 days gestation for the guinea pig which scientists say correlates with the brain growth spurt period for the animal.

The photograph above shows a normal guinea pig brain (left) and the brain of a guinea pig that was exposed to the dibrom ingredient trichlorfon (right) during the critical brain growth period.

The powerful neurotoxic nature of dichlorvos was further emphasized when scientists found these brain abnormalities did not occur when animals were exposed to the other pesticides tested - including Soman - TOCP and ethyl-trichlorfon.

Scientists concluded by stating they suspect the nervous system abnormality occurred due to direct damage to the DNA at a time when the animal's repair systems are not developed.

CHEM-TOX COMMENT:  How many pregnant women in Brevard County may have been at the "critical period" for their child's neurological development will not be known.  However, the fact that this study shows that neurological damage can easily occur in animals (who are often less sensitive than humans to harmful neurological effects) is enough to warrant serious re-evaluation regarding the use of this toxic chemical over populated areas.

University of Oslo, Institute of Biology
Department of Molecular Cell Biology, Oslo, Norway
Norwegian Defense Research Establishment
Division for Environmental Toxicology, Kjeller, Norway

Liver Damage Linked to Mosquito Pesticide Ingredients
Trichlorfon and Dichlorvos

Source: Toxicology, 76:69-77, 1992

Another toxic effect of the chemicals trichlorfon and dichlorvos was identified by researchers at the Osaka City Institute of Public Health and Environmental Sciences.  Here, the scientists found that trichlorfon and dichlorvos caused damage to liver cells from rats treated for 90 minutes with more than 1mM of the chemicals.  Although no significant effect was seen at exposure levels of 0.5mM to control rats exposed to trichlorfon, the scientists did observe 14% liver cell death at 1mM and 20% cell death at 2.0mM.  Regarding the other mosquito control pesticide ingredient dichlorvos, it was shown to be considerably more toxic to liver cells than trichlorfon.  At 1mM exposure level there was 57% liver cell death and 59% cell death at 2.0mM. 

CHEM-TOX COMMENT:  As stated in the Surgical Nursing Manual - 70% of the human liver must be damaged before problems appear in routine blood tests.  Therefore, it can take many years of exposure to liver toxic chemicals to detect damage.  With the information from the above research however, it needs to be considered that a potential does exist for the mosquito pesticides being applied by Brevard's Mosquito Control District to be contributing to accelerated attrition to this vital organ.  While the effects would not be detected immediately in healthy individuals, one must consider the elevated harm that could occur to older or sick individuals whose liver function has already reached the 70% damage threshold.

Tetsuo Yamano
Osaka City Institute of Public Health and Environmental Sciences, Japan

Marine Life Damaged by Pesticide Dibrom

Source: Fish Behavior. Proc. All-Union Science Conference, Nov 20-24, pg. 165, 1989

Research now shows common mosquito control pesticides can cause significant damage to fish throughout our waterways. 

Russian scientists studied the growth rates of Bream (a fish common in Florida) after exposure to the dibrom/naled contaminant known as "dichlorvos."   The first major effect detected was a significant reduction in the growth rates of the fish.  Scientists at the Institute of the Biology of Inland Waters, Russian Academy of Sciences, attempted to locate the exact reasons for this reduction in growth.  They theorized that enzymes in the fish gut were being damaged by the pesticides.  However, this turned out not to be the case, as reported in the Bulletin of Environmental Contamination Toxicology, 52:338, 1994.  Further research is now warranted, but researchers believe it may be due to the subtle neurotoxic actions of the pesticide and its effects upon the areas of the brain involved in feeding or food search mechanisms.

I. L. Golovanova, G. M. Chuiko, D. F. Pavlov
Institute of Biology of Inland Waters, Russian Academy of Sciences
Borok, Yaroslavie Region, Russia

Florida Turtles Suffer Unusually High Cancer Rate

Source: Vero Beach Press Journal, April 21, 1996

Tumors were once a rare occurrence on Florida turtles, however, today it is more the norm.  It was reported that 50-65% of turtles throughout sections of Florida's rivers are being found with tumors over their bodies (note the whitish growths along the front of the turtle's flippers).  Although the tumors are believed to result from viral infections, the fact that only turtles in polluted waters have the tumors raises questions to the potential for pesticides and chemicals to weaken the immune systems of the turtles. It is the immune system that must function properly to constantly remove virus, bacteria and cancer cells as they develop. When the immune system is weakened enough in any living mammal by pesticides, viral and cancer cells can then grow more rapidly, thereby causing greater damage to the organism. 

Central Florida River systems are currently running out of time because of the damaging impact of pesticides and chemicals from lawn spray applications, commercial citrus grove run-off and large scale aerial and truck applications of mosquito control pesticides.  Fish and other aquatic organisms (especially shrimp) have been reported as experiencing mutations in development and alterations in important behaviors critical to the survival of the organism from very low levels of pesticide run-off exposure. 

In an article on the increased number of tumors being found on turtles, appearing in the April 21, 1996 Vero Beach, Press Journal, Florida biologist Liew Ehrhart stated pollution is the"one common thread." Dr. Ehrhart went on to say, 

"It only crops up in populations in degraded water. In bays, sounds and lagoons that have runoff, either urban or agricultural. In pristine water, they don't have the disease."

How long will this problem last?  Apparently it will continue to grow worse as long as we continue to allow pesticides over our lawns - neighborhoods - and families. 


Child Leukemia & Aplastic Anemia after DDVP Exposure
SOURCE: The Lancet, pg.300, August 8, 1981

Seven children with bone marrow disorders have been observed over the past 8 years by physicians at Travis Air Force Base Medical Center in California. The physicians believe the blood disorders, in all cases, were caused by organophosphate pesticides.. All blood disorders occurred shortly after exposure to the pesticides DDVP/propoxur and malathion. The duration of inhaling insecticides ranged from 2 minutes in a patient enveloped in a thick insecticide fog in a small shed to 2 days in other patients whose homes were fumigated by their parents. Six patients had aplastic anemia and one had acute lymphoblastic leukemia. The physicians also cited research showing leukemia in farmers has significantly increased during the period of 1964 to 1976 (Mayo Clinic Proc, 53:714-18, 1978). Apple growers exposed to organophosphates had a higher incidence of leukopenia (very low white blood count) than a control population (Canadian Medical Association Journal, 92:597-602, 1965).

Drs. Jerry D. Reeves, David A. Driggers, Vincent A Kiley
Department of Pediatrics, David Grant Medical Center
Travis Air Force Base, California

Pesticide Exposure Can Increase Infections in Humans
There is now enough solid evidence to state that, in fact, pesticide exposure increases the likelihood of developing bacteria and viral infections.  The area of science that studies this phenomena is called "immuno-toxicology" and investigates how modern chemicals can increase viral and bacteria infections in humans and animals by weakening immune system function (i.e. lowering white blood cell count - slowing white blood cell movement - disarming the mechanisms white blood cells use to locate and destroy virus and bacteria cells - lowering production of the essential immune system regulators interferon - interleukins - and weakening or damaging antibody production).  Currently, manufacturers of Brevard's mosquito control pesticides dibrom and permethrin are not required to test for any of the above health effects.

Don't Be Misled By "Safety" Claims
When chemical representatives (or public officials) state how "SAFE" any given chemical is when trying to calm the fears of the public - keep in mind one of their favorite games.  First - you'll often hear reference to the word "toxic" in their explanations.  This is where the average citizen is dangerously fooled. Most people erroneously judge the danger of any chemical based on the word "toxic."   This occurs because the term "toxic" is loosely referred to as - the amount of a chemical needed to kill an animal or person.  Chemical Industry Spokesmen conveniently forget to mention that there are hundreds of other health effects from chemicals besides their overt toxicity (death).  In fact, if you think about it, death is really the last thing we're concerned about since exposure to levels much lower than those considered "toxic" are being shown to affect the immune and nervous system in many subtle ways. 

Child Cancer Risks from Pesticides and Chemicals

For example, "sub-toxic" effects documented from pesticide exposure can include the biological impact mentioned previously upon the immune system which in turn can cause an increase in viral and bacterial infections - colds - flu - fever - encephalitis - autoimmune disorders (arthritis) - increased asthma incidence - and even cancer (the immune system's "Natural-Killer-Cells" are a class of immune system cells with a voracious appetite for devouring cancer cells in the body).  For more information on how scientists are finding a weakened immune system results in increased child cancers -  please visit our Child Cancer Site at

Infertility Risks from Pesticides and Chemicals

Specific sub-toxic effects from pesticides have also been found to occur to the reproductive processes, which many scientists state is why we are seeing so many more cases of infertility today.  Exposure to pesticides have been found to result not only in infertility, but have also been found to increase the risk of   miscarriage as well as damaging the 65 day sperm development process within the male.  For more information on the ability of pesticides and chemicals to damage the reproductive process please visit or Reproductive Toxicology site at -

Neurological Disorders from Pesticides

Specific sub-toxic neurological effects identified from pesticide exposure include - memory and concentration loss - irritability - headaches - problems with balance - reaction time and even increases in depression (for details and references on these health effects please visit our pesticide toxicology site at

Child Learning and Behavioral Effects from Pesticides

Specific sub-toxic neurological effects have also been found to occur to the developing offspring during pregnancy whose brain is growing at over 4,000 cells per second beginning in the 4th week of pregnancy.   Documented effects from pesticides and other chemicals during this critical brain growth period include - hyperactivity - learning disorders - attention deficit disorder - and aggressive tendencies.  Children with learning disabilities have been found to have brain cells that have migrated to the "wrong" parts of the brain (called dysplasia) as well as showing smaller brain cell size and disorganized column patterns.   If you would like more information on this topic, please visit our Environmental Reproductive Toxicology site at