Immune System Studies
How Pesticides & Chemicals Weaken the Immune System Resulting in Accelerated Viral Growth

ZIKA is reported to cause no symptoms in up to 90% of those bitten by a ZIKA infected mosquito. Of the remaining 10% who do show symptoms, the majority of these are minor and can include fever, headache and rashes. However, in a very small number of cases, the symptoms can become severe and last for extended periods of time, often resulting in visits to the emergency room. Therefore, it is important to find ot why only a small minority of those infected with ZIKA develop severe symptoms? Insight to this question was given by physicians at the Santa Helena Hospital in Camaçari, Brazil, after experiencing a single day outbreak of 24 patients with an apparent viral illness. This is discussed in the first study below the INDEX. If you are unfamiliar with the basics of the immune system, please read the introduction below.

INTRODUCING THE IMMUNE SYSTEM: The immune system is the part of the human body that protects us from harm caused by viruses, bacteria, and cancer. It consists primarily of billions of individual white blood cells roaming throughout our blood stream. The average person has about 7,000 white blood cells in every cubic millimeter of blood (less than a drop). These white blood cells work 'round-the-clock' to kill viruses and bacteria faster than they can multiply. Without it, dangerous organisms would grow rapidly inside our bodies. resulting in death to billions of healthy body cells within hours and eventually death. However, research is now showing that the immune system is extremely sensitive to exposures from pesticides and other chemicals. Even exposures as low as parts per billion to some chemicals can make the difference between an infection taking hold or being eliminated from the body. This will be the focus of this page. One type of white blood cell, called a natural killer cell, is one of the body's first line of defense agains viruses and must work properly to quickly remove viruses. Below are important studies linking immune system impairments and ill health. Please scroll below to view these studies.

Low white blood counts in women with severe ZIKA infection
Study #5
Organotin pesticides cause dramatic loss in natural killer cell function
Study #8
White blood multiply slower in people living in pesticide treated homes.
Study #2
Organochlorine pesticides reduce ability of immune cells to kill viruses
Study #6
Dolphin infections linked to weak immune system & pesticides
Study #9
Common pesticide Atrazine linked to autoimmune disorders (coming soon)
Study #3
Guillian Barre syndrome higher in rural farming district

Study #7
Respiratory illnesses higher in homes treated with pesticides

Study #10
Diabetes higher in people exposed to mosquito control pesticides
Study #4
Mosquito control pesticide naled (dibrom) weakens natural killer cells


Immune system suppression among women infected
with ZIKA - Evidence for confounding factors
Source: Emerging Infectious Disease, Volume 21(10): 1885–1886, Oct 2015

On March 26, 2015, 24 patients with suspected viral illnesses were admitted to the Santa Helena Hospital in Camaçari, Brazil. Blood samples were taken to determine what is called a Complete Blood Count (CBC). (A complete blood count includes several tests including the total number of white blood cells. White blood cells are the backbone of the immune system). Blood samples were also analyzed for the viruses - Dengue, Chik, West Nile, Mayara or Zika (ZIKV) using a method known at RT-PCR at the Federal University of Bahia.

Results showed all patients were negative for Dengue, Mayaro and West Nile viruses. Samples from 3 patients (12.5%) were positive for Chik virus and 7 (29.2%) were positive for ZIKV. There was no simultaneous detection of Chik and ZIKV. Most patients positive for ZIKV were women (85.7%) with no history of international travel.

Complete Blood Count results for these 7 patients with acute ZIKV (Zika Virus) infection showed an average white blood count of 3,750 cells per cubic millimeter of blood. For comparison, the median white blood count in the normal population is approximately 7,000. This shows that ZIKV infected patients had immune system counts that were severely depressed with only a little more than half the numbers found in normal individuals.  In other words, ZIKV infected patients had only about half as many white blood cells to fight the virus as other people. Since low white blood counts do not occur in the majority of people bitten by a ZIKV mosquito, we can rule out that the virus is itself responsible for causing low blood counts.

Looking further into the test results, the white blood counts for the seven ZIKV patients ranged from 2,790 to 6,150. For comparison, the normal population has a range of approximately 4,000 to 10,000. As several patients were below 3,700, this immediately puts them into a category of severely low white blood counts and at a high risk of negative outcome for any viral infection.

MCAN COMMENT: This is the first report we have encountered that provides insight into immune system parameters for ZIKV patients. It is important to know that a type of white blood cell called lymphocytes, is the primary white blood cell for removing viruses from the host. Lymphocytes normally comprise about 30% of all white blood cells). Research over the past decades has also shown that approximately 10% of lymphocytes are in a category known as "natural killer cells." Natural killer cells are one of the very first lines of defense in preventing a virus from taking hold and multiplying (failure of this process then requires other immune system cells to then come into play). Since any defect in the function of lymphoctyes (and natural killer cells) would greatly predispose the individual to an abnormally faster growth of virus cells in the body - it is imperative to further investigate if those with severe ZIKV symptoms have increased contact with conditions known to weaken the human immune system. This information could easily be attained through a background questionarre looking at employment history - proximity to agriculture fields - and even other documented immuno-toxic sources such as dioxin from diesel trucks and burning of plastic based trash. Failure to conduct this next logical phase of research leaves open this critical question. To further support his line of logic, the studies below document sources found to weaken the immune system. This area of science is called Immuno-Toxicology.

Federal University of Bahia
Salvador, Bahia, Brazil (G.S. Campos, S.I. Sardi)
Hospital Aliança, Salvador (A.C. Bandeira)


Organochlorine Pesticides
reduce abilty of NK Cells to Kill Viruses
Source: Human Experimental Toxicology, Vol. 23(10):463-71, Oct 2004
ABSTRACT: Organochlorine pesticides are used worldwide. To our knowledge there have been no studies dealing with the effects of these agents under in vitro conditions on human natural killer (NK) cell cytotoxic function. NK cells play a central role in immune defense against tumor development and viral infections. Thus, any agent that interferes with the ability of NK cells to lyse their targets could increase the risk of tumor incidence and/or viral infections. In this study, we examined the effects of organochlorine pesticides and some of their breakdown products on the ability of human NK cells to lyse tumor cells. A total of 11 compounds were tested. The compounds were tested in both purified NK cells as well as a cell preparation that contained other mononuclear cells (predominantly T cells) and NK lymphocytes (referred to as T/NK cells). Lymphocytes were exposed to the compounds for periods of time ranging from 1 hour to 6 days. Exposure of highly purified NK cells to 5 microM alpha-chlordane, gamma-chlordane, 4,4'-DDT, heptachlor, oxychlordane, or pentachlorophenol (PCP) inhibited their ability to destroy K562 tumor-cells by 88+/-5, 92+/-8, 61+/-13%, 64+/-10%, 69+/-11%, 76+/-12%, respectively, after a 24 h exposure. The loss of cytotoxic function seen with alpha-and gamma-chlordane remained essentially constant out to 6 days, while that seen with 4,4'-DDT, oxychordane and PCP increased with longer exposures (6 d). PCP was the most effective of the compounds tested at decreasing NK function. Of the compounds that caused decreased lytic function when tested in purified NK cells, only PCP and oxychordane decreased the lytic function of the T/NK cell preparation after any exposure. The results provide evidence of relative toxic potential for the 11 compounds and their immunomodulatory effects on other mononuclear cells (such as T-cells, B-cells, and monocytes) as well as NK lymphocyte function.

Department of Chemistry
Tennessee State University
Nashville 37209, USA.

Guillain-Barre Higher in Rural Farming District
Source: Archives of Environmental Toxicology, Vol. 59(11): 575-80, Nov 2004
Background on Guillain-Barre syndrome.
Guillain-Barre is a rapid-onset autoimmune disease characterirzed by muscle weakness. Symptoms can appear over hours or weeks and is caused by the immune system attacking and damaging the peripheral nervous system. It can be life threatening if it affecting breathing muscles.

Abstract from Journal:

Although organophosphate (OP) insecticides have been recognized as having neuropathic potential, a relationship with Guillain-Barre syndrome (GBS) has not been previously confirmed. A cluster of 7 cases of GBS was noted over an 11-yr period in an isolated farming region in the Northern Cape Province of South Africa, an area subject to intensive aerial application of OP insecticides. Observed cases were more than 4 times higher than expected based on a Poisson probability distribution. Four cases were clustered in an area where the topography showed a marked hollow, and where spray drift of aerial OP insecticides was anticipated. The rate of GBS in this subcluster was more than 14 times higher than expected. The authors explored the hypothesis that aerial OP insecticide application was related to the raised incidence of GBS in this area and made suggestions for future research.

MCAN COMMENT: Naled is also an organophosphate pesticide
Mosquito Control Pesticide Naled (Dichlorvos)
and Chlorpyrifos/Lorsban Damage Natural Killer Cells
Source: Toxicology, Vol. 239(1-2):) 89-95, Jul 5, 2007

Natural killer cells are critical for preventing viruses from host infection as well as preventing cance. Loss of function or numbers of these cells increases rates of high viral prevalence and more aggressive cancers. Recently, they have been found to be important for preventing autoimmune disorders by attacking autoimmune T cells. Therefore, any situation that damages natural killer cell number or function has the potential for very serious consequences. Currently, no guidelines from the EPA require pesticide manufacturers to test for or report on damage to natural killer cells or natural killer T cells. The latest research on these immune cells and their importance for preventing illness shows this needs to be modified immediately.

In this study, scientists investigated if the pesticide dichlorvos (a breakdown product of Naled/Dibrom) and the common agricultural pesticide lorsban (chlorpyrifos) were able to damage natural killer cells. Natural killer cells were treated with both dichlorvos and chlorpyrifos at levels from 0 to 100 parts per million for 1 to 72 hours. Results showed that both pesticides caused rapid complete destruction of natural killer cells through a process known as apoptosis in a time and dose-dependent manner. Chlorpyrifos showed a faster response than dichlorvos at higher doses; whereas, dichlorvos showed a slower, but stronger apoptosis-inducing ability at lower doses.

Department of Hygiene and Public Health,
Nippon Medical School,
1-1-5 Sendagi, Tokyo, Japan

Organotin Pesticides Cause Dramatic
Loss of Function to Natural Killer Cells
Source: Environmental Toxicology, Volume 19(6):554-556, Dec 2004

ABSTRACT: Human natural killer (NK) lymphocytes play a central role in immune system defense against viral infection and against the formation of primary tumors (1,2). Organotin (OT) pesticides have been used in industrial and agricultural applications, and OT contamination has been reported in water, sediment, and fish. Carbamate pesticides are currently used in agricultural chemicals. Two specific carbamates used in agriculture are ziram and maneb; ziram also is used as an additive in rubber products including latex gloves. In previous studies we demonstrated that at concentrations in the 150-200 nM range, the OTs tributyltin (TBT) and triphenyltin (TPT) were capable of disrupting the function of human NK cells after incubations to as short as 24 h. Previously, we also examined the effects of ziram and maneb at higher concentrations on the cytotoxic function of human NK cells. The current study examined the effects of exposure of up to 6 days to lower concentrations of each of these compounds on the cytotoxic function of NK cells. The OTs were studied at concentrations ranging from 200 to 10 nM; ziram was studied at concentrations of 2.5 microM-125 nM and maneb at concentrations of 10-1 microM. These conditions were studied both in highly purified NK cells and in a mixture of lymphocytes containing both T and NK cells. As little as 25 nM TBT decreased the function of purified NK cells after 24 and 48 h, whereas 10 nM TBT was effective after 6 days. The lowest level of TPT that was effective at 24 h was 50 nM whereas the results after 48 h and 6 days were similar to those seen with TBT. The presence of T lymphocytes diminished the effects of both TBT and TPT on NK cytotoxic function. A concentration of ziram as low as 125 nM produced significant loss of cytotoxic function in highly purified NK cells (65% decrease in function after 6 days). The toxicity of each of the compounds studied increased very significantly with length of exposure.

Department of Chemistry
Tennessee State University
Nashville, Tennessee 37209, USA

Increased Dolphin Infections Linked to
Immune Systems Suppressed by Pesticides
Source: Environmental Health Perspectives, Volume103 (Suppl 4): 67–72, May 1995

Since 1987, there have been several large-scale dolphin mortalities. Between the midsummer of 1987 and spring of 1988, over 740 bottlenose dolphins were stranded along the Atlantic coast of North Amerca from New Jersey to central Florida. One hypothesis for the dolphin die-offs was infection by the morbillivirus and rotaviruses as these viruses were present in many of the animals. Another theory postulated by the scientists was that chronic exposure to the chemicals PCB's and pesticide DDT could accelerate the development of viral, bacterial and parasitc infections. To test this theory, scientists performed a test of immune function known as "Lymphocyte Proliferation." Lymphocytes (along with natural killer cells) make up about 40% of a mammal's white blood cells and work around the clock to remove viruses from the body. When a lymphocyte first encounters a virus in the body, it begins a process of multiplication (since increased numbers will be beneficial in fighting the virus). 15 dolphins in a "sickened state" were selected and had blood drawn. Blood was then cultured and rated for how well the white blood cells proliferated (multiplied) when exposed to a mitogen. The animals with highest and lowest levels of proliferation were then given a second test to determine the amount of pesticides in the animals' tissue. Results showed that dolphins with the worst lymphocyte proliferation scores had the highest levels fo DDT and PCB's.
CONCLUSION: Background levels of pesticides caused significant weakening of dolphin immune systems, thereby resulting in animal deaths.

MCAN COMMENT: This study lends strong support to the plausibility that individuals having the worst outcome with ZIKA virus may in fact, be experiencing significant suppression of the immune system. As done with the bottle-nose dolphins, a similar lymphoctye proliferation test should be conducted with mothers of microcephaly children suspected of infection with Zika Virus. As Brazil is a highly agricultural setting, levels of pesticides should also be assessed in the suspected population.

Department of Microbiology and Immunology
University of Maryland School of Medicine, Baltimore, Maryland
Chicago Zoological Society, Sarasota, Florida
U.S. Environmental Protection Agency, Duluth, Minnesota
Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland
Dolphin Biology Research Institute, Sarasota, Florida
University of Maryland School of Medicine and Research Service
Baltimore Veterans Administration Medical Center, Baltimore, Maryland

Sinus Infections - Cough - Bronchitis Higher
in Homes Treated with Pesticides
Source: Archives of Environmental Health, Vol. 43(5):349-352, 1988

A study of 261 people who were either living or had lived in homes with higher air chlordane levels were found to have nearly three-times more respiratory illnesses, including sinusitis (infection of the sinuses) and bronchitis. The study, conducted at the School of Public Health, University of Illinois, also found other illnesses significantly more often in the chlordane homes. These included chronic cough, anemia, neuritis, ovarian/uterine disease and skin disorders. The migraine headaches, which was the worst acute symptom found, was occurring in 22% of people living in the higher level chlordane homes.

MCAN Comment:
The symptoms of sinus infections, cough and bronchitis demonstrate effects on the immune system. The following studies document specific impacts chlordane has on the immune system. This information is of significant concern since many countries in South America still use chlordane and other related organochlorine pesticides. Chlordane is what is called an organochlorine pesticide that was banned in the U.S. in 1989.

J. Milton Clark, Ph.D.
School of Public Health
University of Illionois

Immune Cells Multiply Slower
in People Exposed to Pesticides
Potential for Increased Infection & Spread of Disease
Source: Archives of Environmental Health, Vol. 47(4):295-301, Jul-Aug, 1992

MCAN INTRODUCTION: Natural Killer Cells are the body's first line of defense against viruses (1,2). If a virus enters the body and makes it past the natural killer cells and memory cells, the second back-up defense begins. Here, immune system cells called lymphocytes identify the invading virus and begin multiplying to counteract the now rapidly increasing numbers of viruses in the body. In a normal immune system, these rapidly multiplying immune cells remove the virus within one week. However, in others, this is not the case.

In this present study, conducted at the Southern Illionois School of Medicine, scientists tested the ability of a person's white blood cells to multiply when exposed to foreign substances using a common test known as "Proliferative Response." Two groups of people were tested: The first group consisted of 27 individuals who had been exposed to the pesticide chlordane either in their homes or at work while the second group consisted of 118 individuals who were similar with respect to age and sex, but had not been exposed to chlordane.

Results showed that people exposed to even low background levels of the pesticide chlordane had immune system cells that multiplied at only half the rate as people not exposed to the pesticide. Also of interest, 12 random individuals were tested for autoimmunity (a condition in which the immune-system mistakenly attacks health tissues of the body). Of these, 11 people demonstrated increased levels of autoimmune cells (Autoimmunity is the cause of many diseases including diabetes and arthritis).

The ability of chemicals to slow the dividing of immune system cells that attack viruses can have serious consequences - As with most viruses (including ZIKA), a properly working immune system is reported to remove all evidence of the virus within one week. However, if a person's immune cells multiply at a slower rate - rapid viral elimination is not achieved - and the virus will remain in that person for a longer period of time. This not only gives more time for the virus to harm the individual, but also allows for increased spread of the virus to more mosquitoes - and thus, more people. In other words, the application of pesticides meant to reduce viral spread, has now been shown to have the potential to increase the spread of diseases through a multi-step process of immune-suppression. While the pesticide chlordane has been banned in the U.S., it is still routinely used in many South American countries. Also, many current pesticides used in the U.S. are considerably more toxic than chlordane and should also be studied for their ability to lengthen the time of virus survival in humans, as well as in other forms of wildlife that receive dramatically higher rates of pesticide exposure. This is especially of concern for several bird species which are the primary vectors of West Nile virus and other mosquito born diseases. In other words, it is biologically plausible to suspect that pesticides, over the long term, through immune-suppression among humans and wildlife, can have the reverse effect and result in an increase in viral growth rates and spread of diseases.

McConnachie PR
Immunotransplant Laboratory Memorial Medical Center
Springfield, Illiniois

Diabetes Rates 11x Higher in Workers Spraying Pesticides
for Mosquitoes - Warnings to Society?
Source: Journal of Agromedicine, Vol. 19(4):417-26, 2014

Type 1 diabetes is an autoimmune disorder in which the immune system malfunctions and mistakenly attacks insulin producing cells of the pancreas. The rates of diabetes and pre-diabetes was 61% among 116 people employed as mosquito pesticide spray applicators. The rates were less than 8% when compared to 92 people used as controls not exposed to mosquito control pesticides. These rates were calculated from exposure to all types of pesticides. When rates were calculated for those exposed to only pyrethroid based pesticides (such as the common truck mosquito chemical permethrin), diabetes and pre-diabetes rates increased even further to over 18x higher than rates observed in the control group not exposed to pesticides. Diabetes and pre-diabetes were defined as individuals whose blood samples showed an HbA1c level of 5.6% or higher. HbA1c is a form of hemoglobin that attaches to glucose and is an accurate measurement of average blood glucose (sugar) levels over the past several months.

IMPORTANT MCAN COMMENT (Diabetes Background)
All cells in the body and brain require glucose for fuel. Diabetes is a condition in which glucose is unable to do its job properly in the body. Glucose is made from the food we eat and also stored and secreted by the liver while we sleep. Unfortunately, glucose cannot enter cells by itself. To get into the cell, it requires the help of a compound known as insulin. Basically, insulin is the "bus" that carries glucose into the cells, thereby keeping us healthy. An interesting fact: Insulin is made by random cells in the pancreas known as beta-cells. A healthy human pancreas is believed to have 3 to 4 million beta cells. We are fortunate in that we are born with many more beta cells than needed. However, a condition known as pre-diabetes occurs when you have lost approximately 40% of your beta cells. When this happens, your remaining beta cells must work harder to provide enough insulin for the "glucose bus." Unfortunately, there are no symptoms of pre-diabetes, but a person with this condition experiences much highr than normal blood sugar levels after eating a meal. The problem with this is that research shows higher blood sugar levels above 150 cause further weakening and damage to the remaining beta-cells. Therefore, knowing if you have pre-diabetes could dramatically reduce your risk of developing diabetes - since you could then choose to avoid foods that would raise your sugar levels above 150. There is an inexpensive way to do this. Pre-diabetes can be detected with a simple $10 blood glucose meter from Walmart or Krogers Grocery Store. Simply test your blood in the morning before breakfast - a number between 75 and 85 is healthy - a number in the 90's is borderline prediabetes. A number between 100 and 125 is considered prediabetes - and a number over 125 is considered to be full diabetes. To reach full diabetes - it is reported that 80-90% of your beta cells in your pancreases are either not functioning or destroyed. In other words, you no longer have enough "buses" to transport glucose into the cells and so the person must resort to shots of insulin to stay alive. This is precisely what happens in Type-1 diabetes. Of great interest, Type-1 diabetes has been found to be a disorder of the immune system in which the immune system literally becomes "ignorant" and mistakenly targets and destroys beta cells in the pancreas. Of importance here, chemical pesticides (such as those used in home pest control, agriculture and mosquito control) have also been found to cause autoimmunity to the pancreas. Autoimmunity is suspected to occur when the thymus is damaged. The thymus acts like a filter to remove autoimmune cells. Diabetes is increasing at an astounding rate of 4% annually and expected to affect nearly 30% of the U.S. population by the year 2030. By 2050, nearly half the U.S. population could have this dibiliating disease - unless something is done. As the cost of treating diabetes is extremely high - health insurance rates will continue to a point of not being sustainable, with severe consequences to society as a whole. However, the good news is that research over just the past 5 years is identifying specific environmental exposures that can cause autoimmunity (and therefore, Type 1 and possibly Type 2 diabetes) - If these exposure sources are publicized and removed from society, we can stop the trends and most likely reverse the percentage of the population affected by this horrible condition. People who apply pesticides for mosquito control in trucks, planes or backpacks are exposed to far higher levels of pesticides during the mixing and application process - even when preventive measures such as masks are worn. Their increased rates of diabetes may very well be an early warning sign, showing what will happen to the rest of us if we do not reduce or eliminate pesticide exposures in our homes - in our neighborhoods - in our schools and in our lives.

Section for Environment
Occupation and Health
Department of Public Health
Aarhus University, Aarhus, Denmark



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