(Beyond Pesticides, January 8, 2013) Neurologists at the University of California, Los Angeles (UCLA) have published their latest research linking pesticide exposure to Parkinson’s disease. Appearing in the online edition of PNAS, the UCLA scientists’ work details the series of events that can occur after individuals are exposed to the pesticide benomyl, which was phased out in 2001. Researchers believe their findings on the series of events the pesticide sets in motion could be applicable even to Parkinson’s patients who have not been exposed to benomyl. According to scientists, exposure to benomyl prevents the enzyme aldehyde dehydrogenase (ALDH) from keeping in check a naturally occurring toxin in the brain called 3,4-Dihydroxyphenylacetaldehyde (DOPAL). Without ALDH regulating DOPAL, the toxin accumulates, damages neurons, and increases an individual’s risk of developing Parkinson’s disease. Researchers postulate that this process may be occurring in people with Parkinson’s who were never exposed to pesticides. The findings of this research provide insight into possible treatments to slow the disease, such as developing new drugs to protect ALDH activity. Although the exact cause of Parkinson’s is still unknown, until this research scientists were focusing in on the protein a-synuclein as a pathway to the disease. The protein, present […]

(Beyond Pesticides, December 10, 2012) Long-term low-level exposure to organophosphate pesticides produces lasting damage to neurological and cognitive functions, according to researchers at University College London (UCL). This research pulls data from 14 studies over the past 20 years, including more than 1,600 participants, in order to provide a quantitative analysis of the current literature on these dangerous chemicals. Lead author of the study, Sarah Mackenzie Ross, Ph.D., notes, “This is the first time anyone has analyzed the literature concerning the neurotoxicity of organophosphate pesticides, using the statistical technique of meta-analysis.” UCL’s systematic review, published in the journal Critical Reviews in Toxicology, comes to an unsettling conclusion about the hazards of constant low-level occupational exposure to organophosphates. The study notes, “The majority of well designed studies found a significant association between low-level exposure to [organophosphates] and impaired neurobehavioral function which is consistent, small to moderate in magnitude and concerned primarily with cognitive functions such as psychomotor speed, executive function, visuospatial ability, working and visual memory.” In other words, low-level exposure had significant detrimental effect on working memory and information processing. The researchers are hopeful that the results of their analysis will be used to inform governments performing reviews on the […]

(Beyond Pesticides, November 14, 2012) For years, scientists have shown that pesticide exposures are linked to the onset of Parkinson’s disease. Now a new study by researchers at University of California, Los Angeles, (UCLA) finds that exposure to pesticides and suffering a head injury are associated with a three-fold increase in one’s chances of developing Parkinson’s disease. Parkinson’s disease is the second most common neurodegenerative disease, and occurs when nerve cells in the substantia nigra region of the brain are damaged or destroyed and can no longer produce dopamine, a nerve-signaling molecule that helps control muscle movement. People with Parkinson’s disease have a variety of symptoms, including loss of muscle control, trembling and lack of coordination. Over time, symptoms intensify. At least one million Americans have Parkinson’s and about 50,000 new cases are diagnosed each year. The study, “Traumatic brain injury, paraquat exposure, and their relationship to Parkinson disease,” published in the journal Neurology surveyed more than 1,000 adults ages 35 and older who lived in central California. Some 357 of the participants were diagnosed with Parkinson’s disease. Participants with the disease were nearly twice as likely as those without the disease to report having had a head injury in […]

(Beyond Pesticides, June 29, 2012) New research from the McGill University Health Centre (MUHC) in Montreal suggests that pesticide exposure, as well as smoking, head injury, farming, and less education, may be a risk factor for a rare sleep disorder that causes people to kick or punch during sleep, according to a study entitled “Environmental risk factors for REM sleep behavior disorder: A multicenter case-control study” published in the June 27, 2012, online issue of Neurology, the medical journal of the American Academy of Neurology. People with the disorder, called REM sleep behavior disorder, do not have the normal lack of muscle tone that occurs during rapid eye movement (REM) sleep, causing them to act out their dreams. The movements can sometimes be violent, causing injury to the person or their bed partner. The disorder is estimated to occur in 0.5 percent of adults. “Until now, we didn’t know much about the risk factors for this disorder, except that it was more common in men and in older people,” said study author Ronald B. Postuma, MD, MSc, with the Research Institute at MUHC and a member of the American Academy of Neurology. “Because it is a rare disorder, it was […]

(Beyond Pesticides, June 15, 2012) Researchers at the Duke University School of Medicine have developed a laboratory screening system for detecting neurotoxic chemicals and successfully tested it on more than 1,400 potential toxicants. The study confirms the high toxic activity of the chemical piperonyl butoxide (PBO), a chemical “synergist” used to increase the potency of more than 700 insecticides, including synthetic pyrethroids widely used in mosquito and community spray programs and for home use. The study, entitled “The Insecticide Synergist Piperonyl Butoxide Inhibits Hedgehog Signaling: Assessing Chemical Risks,” was published in the May 2012 edition of the journal Toxicological Sciences. The testing shows that PBO disrupts a biological signaling system that is “critical in neurological development,” the researchers reported in the abstract of their paper. The study finds that the disruption of this critical pathway “may be the molecular basis for profound developmental defects in children exposed in utero to PBO.” Piperonyl butoxide is not itself classified as a pesticide, but companies combine it with insecticides to increase their potency. PBO came into widespread use when the U.S. Environmental Protection Agency (EPA) phased out chlorpyrifos and other organophosphate pesticides nearly a decade ago after determining that they posed a risk […]

(Beyond Pesticides, April 13, 2012) A study has found that the children of flower plantation workers in Ecuador are neurologically affected by the pesticide residues that their parents unwittingly carry home on their clothes, tools, and skin. The study documents significantly reduced activity for the essential enzyme acetycholinesterase (AChE) in children whose parents work on flower plantations compared to others whose parents do not. The two main classes of pesticides that the researchers identify as used in the region’s flower production, organophosphates and carbamates, are known to suppress the enzyme’s activity. AChE activity is crucial to healthy neurological functioning in humans and its suppression during childhood can hinder nervous system and cognitive development causing immediate and long-term impairment. In the study, Lower acetylcholinesterase activity among children living with flower plantation workers (Environ Res. 2012 Apr;114:53-9. Epub 2012 Mar 10), children whose parents work on a flower plantation are more than three times more likely to be in the group of lowest AChE activity. Additionally, the children who live the longest with a flower plantation worker are four times more likely to have lower enzyme activity than children who never live with a plantation worker. The researchers obtained their results by […]

(Beyond Pesticides, August 11, 2011) A combination of eleven different kinds of commonly used pyrethroids were tested on mice in a new study which found that, at real-world exposure levels, the insecticides can produce heightened toxicity that is equal to the sum of each insecticide’s individual effect. The mixture of similar-acting insecticides works by over-stimulating electronic channels in the mouse’s brain cells and eventually causing death. This study adds to the growing body of research on the toxicity of pesticide combinations in nature and showcases the need for policy change because the current risk assessment approach to regulating pesticides fails to look at chemical mixtures and synergistic effects. The U.S. Environmental Protection Agency (EPA) currently regulates on a chemical-by-chemical basis, but as this study demonstrates, interacting chemicals can have synergistic effects at very low levels, where a “chemical cocktail” of multiple interacting chemicals combine to have greater effects than expected. Pesticides can also have a cumulative “toxic loading” effect both in the immediate and long term. Researchers exposed mice brain cells to eleven different food-use pyrethroid insecticides either singly or in a mixture in the study entitled ”Additivity of pyrethroid actions on sodium influx in cerebrocortical neurons in primary culture.” […]

(Beyond Pesticides, June 28, 2011) Recent studies have linked Parkinson’s disease to pesticide exposure. In a new article published in the journal Molecular Neurodegeneration, researchers at the University of Missouri School of Medicine take some of the first steps toward understanding this link and unraveling the molecular dysfunction that occurs when proteins are exposed to environmental toxins. The study, “Oxidation of the cysteine-rich regions of parkin perturbs its E3 ligase activity and contributes to protein aggregation,” helps further explain recent NIH findings that demonstrate the link between Parkinson’s disease and two particular pesticides — rotenone and paraquat. “Fewer than 5 percent of Parkinson’s cases are attributed to genetics, but more than 95 percent of cases have unknown causes,” said Zezong Gu, MD, PhD, assistant professor of pathology and anatomical sciences. “This study provides the evidence that oxidative stress, possibly due to sustained exposure to environmental toxins, may serve as a primary cause of Parkinson’s. This helps us begin to unveil why many people, such as farmers exposed to pesticides, have an increased incidence of the disease.” Scientists previously understood that Parkinson’s is associated with oxidative stress, which is when electronically unstable atoms or molecules damage cells. The MU study yields […]

(Beyond Pesticides, May 31, 2011) A study has found that people whose workplaces were close to fields sprayed with chemicals — not just those who live nearby — are at higher risk of developing Parkinson’s disease (PD). The pesticide chemicals in question include two fungicides -maneb (in the ethylene bisdithiocarbamate (EDBC) family and ziram (in the dimethylthiocarbamate family)- and the herbicide paraquat that appear to raise the risk of developing the movement disorder. In a study published in the European Journal of Epidemiology, entitled, “Parkinson’s disease risk from ambient exposure to pesticides,” a team of researchers led by UCLA neurologist Beate Ritz, PhD found that exposures to the trio of pesticides are actually higher in workplaces located near sprayed fields than they were in residences. And the combination of exposure to all three pesticides, which act in different ways to harm brain cells involved in Parkinson’s disease, appears to be cumulative, the team led by Dr. Ritz concludes. The study found that the combined exposure to pesticides ziram, maneb and paraquat near any workplace increased the risk of Parkinson’s disease threefold, while combined exposure to ziram and paraquat alone was associated with an 80% increase in risk. The researchers estimate […]

(Beyond Pesticides, February 17, 2011) According to a recent investigative report, a company known for conducting scientific research for the pesticide industry has, in an attempt to refute research linking pesticides to Parkinson’s disease, paid a U.S. government agency, the National Institute for Occupational Safety and Health (NIOSH), to prove that certain pesticides are safe. According to the report, the company, Exponent Inc., is a member of CropLife America, a trade group that represents pesticide manufacturers, and also has worked regularly for Syngenta, which makes paraquat, one of the chemicals it is looking prove as safe. Specifically, the company is looking to refute the research which shows that even small amounts of agricultural chemicals, maneb and paraquat, when combined, can raise the risk of Parkinson’s disease. According to the report, managing scientist of Exponent, Laura McIntosh, PhD, said in an interview that the company donated the money and sought participation at NIOSH to enhance the credibility of its study of maneb and paraquat; they wanted to make their research “bulletproof.” NIOSH is a division of the Centers for Disease Control and Prevention (CDC). Generally, government agencies are supposed to be unbiased, and federal ethics rules prohibit employees from accepting money […]

(Beyond Pesticides, February 16, 2011) Many agricultural pesticides —including some previously untested and commonly found in food— disrupt male hormones, according to new tests conducted by British scientists. Meanwhile, U.S. researchers at the National Institutes of Health have found that people who used two specific varieties of pesticide were 2.5 times as likely to develop Parkinson’s disease. Pesticides Impact Male Hormones Evidence suggests that there is widespread decline in male reproductive health and anti-androgenic pollutants, also known as endocrine disruptors, may play a significant role. Thirty out of 37 pesticides tested by the researchers at the University of London altered male hormones, including 16 that had no known hormonal activity until now. There was some previous evidence for the other 14. Most are fungicides applied to fruit and vegetable crops, including strawberries and lettuce. The study, “Widely Used Pesticides with Previously Unknown Endocrine Activity Revealed as in Vitro Anti-Androgens,” is published in Environmental Health Perspectives. The British researchers screened the chemicals using in vitro assays, which use human cells to check whether the pesticides activate or inhibit hormone receptors in cells that turn genes on and off. Scientists, however, are uncertain what actually happens in the human body at the […]

(Beyond Pesticides, Aug 2, 2010) A new report conducted by an Ann Arbor, Michigan based coalition of health and environmental groups estimates that children’s exposure to toxic chemicals, including pesticides, cost Michigan billions of dollars each year. The study examines the costs associated with four environmentally related childhood diseases: lead poisoning, asthma, pediatric cancer, and neurodevelopmental disorders. Treating these four disorders costs the state of Michigan an average of $5.85 billion annually. The study, “The Price of Pollution: Cost Estimates of Environment-Related Childhood Disease in Michigan” was released in time for the US House Energy and Commerce Committee hearings on the Toxic Chemicals Safety Act of 2010, an overhaul of the 1976 Toxic Substances Control Act (TSCA). Using conservative estimates researchers consider direct costs such as medical treatment, as well as less direct costs such as parent wage losses. The study also notes the substantial emotional costs to families dealing with these potentially life threatening or debilitating conditions which cannot be quantified. Lead poisoning is found to be the most costly of the diseases studied, costing on average $4.85 billion annually, followed by childhood asthma, pediatric cancer, and neurodevelopmental disorders. These four disorders alone cost the state of Michigan 1.5% […]

(Beyond Pesticides, June 16, 2010) Men with certain genetic variations who were exposed to some toxic pesticides that are now largely banned run an increased risk of developing Parkinson’s disease, French scientists said Monday. In a study published in Archives of Neurology, entitled “Interaction Between ABCB1 and Professional Exposure to Organochlorine Insecticides in Parkinson Disease,” French researchers found that among men exposed to pesticides such as DDT, carriers of the gene variants are three and a half times more likely to develop Parkinson’s than those with the more common version of the gene. The scientists think the brains of people with the gene variant fail to flush out toxic chemicals as efficiently as those with common versions of the gene, suggesting that environmental as well as genetic factors are important in the risk of Parkinson’s. Alexis Elbaz, MD, PhD and Fabien Dutheil, PhD, of France’s National Institute for Health and Medical Research (INSERM) studied 101 men with Parkinson’s and 234 without the disease to look at links between organochlorine exposure and Parkinson’s disease. The study includes only men, and all of them had high levels of exposure to pesticides through their work as farmers. The scientists found the link was […]

(Beyond Pesticides, May 28, 2010) The repeated exposure to organophosphate and organochlorine insecticides can increase the risk of developing Alzheimer’s Disease (AD) or dementia later in life according to a new study published in the May issue of Neurology. The observational study entitled “Occupational exposure to pesticides increases the risk of incident AD” is one of very few studies to examine a link between pesticides and AD. Researchers lead by Kathleen M. Hayden, PhD of Duke University Medical Center examined residents 65 years and older from an agricultural community in Cache County Utah. Participants were assessed for cognitive ability at the inception of the study and again after 3, 7, and 10 years. Data showed that those repeatedly exposed to any pesticides were more likely to develop AD or dementia. Researchers found a higher incidence of AD among those exposed to organophosphates and organochlorines. The risk of AD associated with organophosphate exposure was slightly higher than the risk associated with organochlorines. Researchers also found an increase in dementia among those exposed to organophosphates or organochlorines; however this increase was not statistically significant. Dr. Hayden said that more research was necessary to determine a causal link. Organophosphates are known to reduce […]

(Beyond Pesticides, January 11, 2010) Yet another study has been published that further supports the causative link between pesticide exposure and Parkinson’s disease. The study, funded by the National Institute of Environmental Health Sciences (NIEHS), is published in the January issue of Epidemiology. The University of California, Los Angeles researchers looked at the association between Parkinson’s disease, organophosphate pesticides and the common gene variant, paraoxonase-1 gene Leu-Met 55 polymorphism (PON1-55 MM). The findings show that study participants with two copies of gene variant have a significantly increased risk of developing Parkinson’s disease when exposed to certain organophosphate pesticides used in agriculture. The population-based case-control study examined the DNA of 351 incident cases and 363 controls from three rural counties in California. The researchers then used pesticide usage reports and a geographic information system (GIS) approach to determine the study participants’ residential exposure to organophosphates. The PON1 gene codes for an enzyme that metabolizes organophosphate pesticides. Individuals with the variant MM PONI1-55 genotype that are exposed to organophosphates exhibit more than twice the risk of Parkinson’s disease compared to carriers of wildtype or heterozygous genotype and no exposure. In regards to exposure to diazinon, carriers of variant MM PONI-55 genotype show […]

(Beyond Pesticides, September 16, 2009) A new study published in the September issue of Archives of Neurology reports that the risk of Parkinsonism doubled with increased occupational exposure to pesticides, including eight agents associated with experimental Parkinsonism. These data add to the growing number of studies that lend credence to a causative role of certain pesticides in neurological disorders. The study, “Occupation and Risk of Parkinsonism: A Multicenter Case-Control Study,” set out to investigate occupations, specific job tasks, or exposures and risk of parkinsonism in collaboration with eight movement disorders centers in North America including, the Parkinson’s Institute, CA, Department of Neurology, Baylor College of Medicine and Department of Neurology, Beth Israel Medical Center, New York. The investigation focused on five occupations previously suggested as posing an increased risk of Parkinsonism: agriculture, education, healthcare, welding, and mining. This examination of toxicant exposures included solvents and pesticides putatively associated with Parkinsonism. 519 people with Parkinson’s disease and 511 similar people who did not have Parkinson’s were studied. Overall, the study finds that those whose jobs involve using pesticides are 80 percent more likely to develop the condition. The data reveals that any exposure to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) almost triples […]

(Beyond Pesticides, August 12, 2009) A new study examining the effects of the mosquito repellent DEET on insects, mice and human proteins reports that the chemical interferes with a prominent central nervous system enzyme. This effect is magnified when exposure to DEET is combined with exposure to certain other pesticides. Entitled, “Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet,” and published in BioMed Central (BMC) Biology, the study utilized toxicological, biochemical and electrophysiological techniques to show that DEET is not simply a behavior-modifying chemical, but that it also inhibits cholinesterase activity in both insect and mammalian neuronal preparations. The researchers examined DEET’s effects on mosquitoes, cockroach nerves, mouse muscles, and enzymes purified from fruit flies and humans. Applications of DEET slowed or halted the actions of the enzyme acetylcholinesterase. This enzyme is crucial for regulating nerve impulses in both insects and mammals, and once its functions are disrupted, neuromuscular paralysis, leading to death by asphyxiation result. In humans, symptoms include headache, exhaustion and mental confusion together with blurred vision, salivation, chest tightness, and muscle twitching and abdominal cramps. The study also investigated the consequences of DEET interactions with carbamate insecticides on the […]

(Beyond Pesticides, August 7, 2009) A recent study published in the journal Environmental Health Perspectives has added to evidence that certain pesticides significantly increase one’s risk of developing Parkinson’s disease (PD). Researchers found that rural residents who drank private well water within 500 meters of fields sprayed with certain pesticides had an increased – up to 90 percent – risk of developing PD, and those with Parkinson’s “were more likely to have consumed private well water, and had consumed it on average 4.3 years longer.” The study evaluated more than 700 people, including carefully chosen controls, in Fresno, Kent, and Tulare counties. 17 percent reported drinking private well water between 1974 and 1999. Researchers focused on wells’ proximity to agricultural fields sprayed with pesticides, since private wells are not regulated, and many are shallow enough to be contaminated by pesticides seeping into groundwater. Researchers looked at 26 pesticides and six in particular, “selected for their potential to pollute groundwater or because they are of interest for PD, and to which at least 10% of our population were exposed.” Those are: diazinon, chlorpyrifos, propargite, paraquat, dimethoate, and methomyl. Propargite exposure was most closely correlated with incidence of PD, with a 90 […]

(Beyond Pesticides, July 30, 2009) A new report from the Institute of Medicine (IOM) and sponsored by the U.S. Department of Veterans Affairs finds suggestive but limited evidence that exposure to Agent Orange and other herbicides used during the Vietnam War is associated with an increased chance of developing ischemic heart disease and Parkinson’s disease in Vietnam veterans. The report is the latest in a congressionally mandated series by IOM that every two years reviews the evidence about the health effects of these herbicides and a type of dioxin – TCDD – that contaminated some of the defoliants. A finding of “limited or suggestive evidence of an association” means that the evidence indicates there could be a link between exposure to a chemical and increased risk for a particular health effect, though conflicting results from studies, problems with how the studies were conducted, or other confounding factors limit the certainty of the evidence. Until now, the cumulative evidence had been inadequate to draw conclusions about whether these two conditions may be associated with veterans’ exposures to herbicides or TCDD. Ischemic heart disease – a condition characterized by reduced blood supply to the heart, which can lead to heart attack and […]

(Beyond Pesticides, June 8, 2009) A new epidemiological study finds that Parkinson’s disease patients who have been exposed to pesticides through their work show elevated rates of the disease. The researchers find that French farmworkers have nearly double the risk for the disease if exposed to pesticides, with a dose-effect for the number of years of exposure. When they looked at the three major classes of pesticides (insecticides, fungicides and herbicides), they find that the farmworkers who used insecticides had over a two-fold increase in the risk of Parkinson’s disease. A slightly higher risk is found for exposure to organochlorine insecticides. According to the study, these associations are stronger in men with older onset Parkinson’s disease than in those with younger onset Parkinson’s. The study, “Professional Exposure to Pesticides and Parkinson’s Disease,” published in Annals of Neurology, involved individuals affiliated with the French health insurance organization for agricultural workers who were frequently exposed to pesticides in the course of their work. Occupational health physicians constructed a detailed lifetime exposure history to pesticides by interviewing participants, visiting farms, and collecting a large amount of data on pesticide exposure. These included farm size, type of crops, animal breeding, which pesticides were used, […]

(Beyond Pesticides, March 16, 2009) Exposure to a mixture of the fungicide maneb and the herbicide paraquat significantly increases the risk of developing Parkinson’s disease, according to a new University of California, Berkeley study, “Parkinson’s Disease and Residential Exposure to Maneb and Paraquat from Agricultural Applications in the Central Valley of California.” Published in the American Journal of Epidemiology, the study findings show that exposure to both pesticides within 500 meters of an individual’s home increases the risk of developing Parkinson’s by 75 percent. For individuals 60 years of age or younger at the time of diagnosis, there is a more than four-fold increase in risk of the disease when exposed to a combination of maneb and paraquat and a more than doubling of risk when exposed to either maneb or paraquat alone. The Berkeley researchers used geographic information systems that analyzed data from California Pesticide Use Reports and land-use maps to calculate historical residential exposure to agricultural exposure to the two pesticides. From 1998 to 2007, the researchers enrolled 368 incident Parkinson’s disease cases and 341 population controls from California’s Central Valley and developed potential exposure estimates incurred between 1974 and 1999. Also published this month by some of […]

(Beyond Pesticides, March 2, 2009) Pesticide exposure and genetic variability in the dopamine transporter (DAT), a protein that plays a central role in dopaminergic neurotransmission of the brain, interact to significantly increase the risk factor for Parkinson’s disease, according to a new study by University of California, Los Angeles (UCLA) researchers. The population based case-control study, “Dopamine Transporter Genetic Variants and Pesticides in Parkinson’s Disease,” builds on the existing body of evidence of animal data and epidemiological studies that link exposure to pesticides, including gene-pesticide interactions, to Parkinson’s disease. The UCLA researchers, looking at incident Parkinson’s disease cases in three rural counties in Central California, find DAT increases the risk of Parkinson’s when individuals have occupational or residential exposure to pesticides. This is the first epidemiologic study of Parkinson’s disease that relies on pesticide data that is from a record-based source versus recall-based data relying on individuals’ memory. The second most common neurodegenerative disease affecting more than one million people in the U.S., Parkinson’s disease occurs when nerve cells in the substantia nigra region of the brain are damaged or destroyed and can no longer produce dopamine, a nerve-signaling molecule that helps control muscle movement. The new UCLA study is […]

(Beyond Pesticides, December 1, 2008) A new study by researchers at the University of California Los Angeles finds chronic exposure to commonly used dithiocarbamate fungicides, such as ziram, contribute to the development of Parkinson’s disease. According to the study, Ziram Causes Dopaminergic Cell Damage by Inhibiting E1 Ligase of the Proteasome, published in the Journal of Biological Chemistry, researchers screened several pesticides for their ability to interfere with the ubiquitin-proteasome system (UPS). Impaired UPS activity is reported in Parkinson’s disease patients’ brains. The researchers then focused on dithiocarbamate fungicides because they were found to be one of the most potent UPS inhibitors and are commonly used. The researchers discovered the mechanisms by which the UPS is impaired, showing that ziram and structurally related dithiocarbamates inhibit E1 ligase (a protein activating enzyme). Ziram is also found to increase alpha-synuclein (a protein expressed in the central nervous system) levels and selectively damages dopaminergic neurons in vitro. The study also cites unpublished data from a population-based study in central California that is determining pesticide exposure using state application registry, finding that individuals living within 500 meters of where ziram is applied are at three times the increased risk of developing Parkinson’s compared to […]