A new study in China has found that people with higher levels of pesticide exposure are more likely to have suicidal thoughts. The study was carried out by Dr Robert Stewart from the Institute of Psychiatry at King’s College London together with scientists from Tongde Hospital Zhejiang Province. 

The agricultural pesticides commonly used in China are organophosphates which are in wide use in many lower income countries but have been banned in many Western nations. It is well known that they are very dangerous if ingested as an overdose but there is also biological evidence that chronic low-grade exposure to these chemicals, which are very easily absorbed into the body through the skin and lungs, may have adverse effects on mental health. This study is the first epidemiological evidence to suggest possible effects on suicidal thoughts. 

The study was carried out in central/coastal China, a relatively wealthy area with a rapidly developing economy. In a very large survey of mental health in rural community residents, participants were also asked about how they stored pesticides. The study found that people who stored pesticides at home, i.e. those with more exposure, were more likely to report recent suicidal thoughts. Supporting this, the survey also found suicidal thoughts to be associated with how easily accessible these pesticides were in the home and that the geographic areas with highest home storage of pesticides also had highest levels of suicidal thoughts in their populations. 

Given the high level of pesticide exposure and the high suicide risk in rural China, clarification of the causal mechanisms underlying this association and the development of appropriate interventions should be priorities for public health and health policy. 

Dr Robert Stewart comments: ‘Organophosphate pesticides are widely used around the world although are banned in many countries because of their risk to health. They are particularly lethal chemicals when taken in overdose and are a cause of many suicides worldwide. Our research findings that suggest that higher exposure to these chemicals might actually increase the risk of suicidal thoughts provides further support for calls for tighter international restrictions on agricultural pesticide availability and use.’

Dr Jianmin Zhang, Associate Chief Psychiatrist, Tongde Hospital of Zhejiang Province, and Vice Director, Zhejiang Office of Mental Health, China added: “The findings of this study suggested potential causal links and might partially account for the much higher incidence of suicide in rural than urban areas of China. However, further studies particularly with more precisely defined and assessed exposure are critically needed, as awareness of safer access to pesticides is important both to policy-makers and pesticide users.”

Reference: King’s College London, Pesticides exposure linked to suicidal thoughts, October 22, 2009  

Notes:

Pesticide exposure and suicidal ideation in rural communities in Zhejiang province, China by Jianmin Zhang, Robert Stewart, Michael Phillips, Qichang Shi & Martin Prince was published in the October issue of the WHO Bulletin. The full article can be accessed on http://www.who.int/bulletin/volumes/87/10/08-054122.pdf 

The analysis involved data from a survey of a representative sample of 9,811 rural residents in Zhejiang province who had been asked about the storage of pesticides at home and about whether or not they had considered suicide within the two years before the interview. The Chinese version of the 12-item General Health Questionnaire (GHQ) was administered to screen for mental disorder.

Breakthrough study on Multiple Chemical Sensitivity shows MCS is an epidemic caused by toxic chemicals; peer-reviewed paper is published in prestigious toxicology reference work.

A major paper on multiple chemical sensitivity by Professor Martin L. Pall is to be published October 23, 2009 as chapter XX in a prestigious reference work for professional toxicologists, “General and Applied Toxicology, 3rd Edition” (John Wiley & Sons).  Multiple chemical sensitivity (MCS) is also known as chemical sensitivity, chemical intolerance and toxicant-induced loss of tolerance, with this last name emphasizing the role of chemicals in initiating cases of this disease.  Pall’s  paper, entitled Multiple Chemical Sensitivity: Toxicological Questions and Mechanisms, establishes five important facts about  MCS:

1. MCS is a stunningly common disease, even more common than diabetes.  This has been shown in a series of nine epidemiological studies from the U.S. and one study each from Canada, Germany, Sweden and Denmark.  In the U.S., approximately 3.5% of the population is affected by severe MCS, with much larger numbers, at least 12% of the population, being moderately affected.  MCS is, therefore, a very large international disease epidemic with major implications in terms of public health.

2. MCS is caused by toxic chemical exposure.  Cases of MCS are initiated by exposure to seven classes of chemicals.  These include three classes of pesticides and the very large class of organic solvents and related compounds.  In addition, published studies implicate mercury, hydrogen sulfide and carbon monoxide as initiators.  All seven of these classes of chemicals have been shown in animal studies to produce a common response in the body, excessive activity of a receptor in the body known as the NMDA receptor.  Furthermore animal studies have demonstrated that chemicals belonging to each of these seven classes can have their toxic responses greatly lowered by using drugs that lower this NMDA response.  Because excessive NMDA activity is implicated in MCS from other studies, we now have a compelling common response that explains how such diverse chemicals can produce the disease that we call MCS.

3. The role of chemicals acting as toxicants in MCS has been confirmed by genetic studies.  Four such studies have shown that genes that determine the rate of metabolism of chemicals otherwise implicated in MCS, influence susceptibility to becoming ill with MCS.  These four studies have been published by three research groups in three countries, the U.S., Canada and Germany, have collectively implicated six genes in determining susceptibility to MCS.  Each of these six genes has a role in determining the rate of metabolism of MCS-related chemicals.  The German studies by Schnakenberg and colleagues are particularly convincing on this because of the extremely high level of statistical significance of their studies implicating four of these six genes. There is only one interpretation for the role of these six genes in determining susceptibility to MCS.  It is that chemicals act as toxicants in initiating cases of MCS and that metabolizing these chemicals into forms that are either less or more active in such initiation, influences therefore, the probability that a person will become ill with MCS.  It is clear, therefore, that MCS is a toxicological phenomenon, with cases being caused by the toxic response to chemical exposure.

4. We have, a detailed and generally well supported mechanism for MCS.   This mechanism explains both the high level chemical sensitivity that is the most characteristic symptom of MCS, as well as many other symptoms and signs of this disease, can be generated.   This mechanism is centered on a biochemical vicious cycle, known as the NO/ONOO- cycle, which interacts with other mechanisms previously implicated in MCS, notably neural sensitization and neurogenic inflammation.  These act locally, in various tissues of the body, to generate local sensitivity in regions of the brain and in peripheral tissues including lungs, upper respiratory tract and regions of the skin and the GI tract.  Because of this local nature, different MCS patients differ from one another in their sensitivity symptoms, because the tissues impacted differ from one patient to another.  In addition to the evidence discussed above, this general mechanism is supported by various physiological changes found in MCS and in related illnesses, by studies of MCS animal models, by objectively measurable responses of MCS patients to low level chemical exposure and by therapeutic responses reported for MCS and related illnesses.

5. For over 20 years, some have falsely argued that MCS is a psychogenic disease, being generated in their view by some ill defined psychological mechanism.  However this view is completely incompatible with all of the evidence discussed earlier in this release. While such incompatibility is more than sufficient reason to reject these psychogenic claims, the MCS toxicology paper lists eight additional serious flaws in the psychogenic arguments.  There is a long history of false psychogenic claims in medicine, where such diseases as asthma, autism, Parkinson’s disease, ulcers, multiple sclerosis, lupus, interstitial cystitis, migraine and ulcerative colitis have been claimed to be generated by a psychological mechanism.  The 2005 Nobel Prize in physiology and medicine was give to Drs. Robin Warren and Barry Marshall for showing that ulcers are caused by a bacterial infection, and are not of psychogenic origin.  It is clear, now, that MCS is physiological disease initiated by toxic chemical exposure that has been falsely claimed to be psychogenic.

—

Martin L. Pall is Professor Emeritus of Biochemistry and Basic Medical Science, at Washington State University.

He is located on Pacific time in the U.S. and can be contacted at:  503-232-3883 and at martin_pall@wsu.edu.

His Website is: www.thetenthparadigm.org

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• Environmental Medicine: Dr. Martin Pall about Chemical Sensitivity
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• Multiple Chemical Sensitivity at General and Applied Toxicology 3rd Edition

Although it is known that infants are more susceptible than adults to the toxic effects of pesticides, this increased vulnerability may extend much longer into childhood than expected, according to a new study by researchers at the University of California, Berkeley.

Among newborns, levels of paraoxonase 1 (PON1), an enzyme critical to the detoxification of organophosphate pesticides, average one-third or less than those of the babies’ mothers. It was thought that PON1 enzyme activity in children approached adult levels by age 2, but instead, the UC Berkeley researchers found that the enzyme level remained low in some individuals through age 7.

Based upon the findings, reported this month in the journal Environmental Health Perspectives, the study authors recommend that the U.S. Environmental Protection Agency (EPA) re-evaluate the current standards for acceptable levels of pesticide exposure.

“Current EPA standards of exposure for some pesticides assume children are 3 to 5 times more susceptible than adults, and for other pesticides the standards assume no difference,” said Nina Holland, UC Berkeley adjunct professor of environmental health sciences and senior author of the paper. “Our study is the first to show quantitatively that young children may be more susceptible to certain organophosphate pesticides up to age 7. Our results suggest that the EPA standards need to be re-examined to determine if they are adequately protecting the most vulnerable members of the population.”

In 2001, the EPA began restricting organophosphate pesticides in products sold for use in homes, mainly because of risks to children. However, organophosphate pesticides, such as chlorpyrifos and diazinon, are still used in agriculture in the United States and elsewhere.

The study, conducted by UC Berkeley’s Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), involves 458 children from an agricultural region who were followed from birth through age 7. Cord blood samples were collected from all children to determine their PON1 genotype and to obtain baseline measures of the enzyme’s activity level.

For more than 100 of the children in the study, researchers were able to obtain at least four additional measurements – at ages 1, 2, 5 and 7 – of PON1 activity. Almost all the children in the study had 2 to 3 time points assessed, for a total of 1,143 measurements of three types of PON1 enzyme activity.

One’s PON1 genotypic profile determines how effectively the enzyme can metabolize toxins. For example, people with two copies of the Q form of the gene – known as a QQ genotype – produce a PON1 enzyme that is less efficient at detoxifying chlorpyrifos oxon, a metabolite of chlorpyrifos, than the enzyme produced by people with two R forms of the gene. Similarly, individuals with two T forms of the PON1 gene on a different part of the chromosome generally have a lower quantity of the enzyme than do those with two C forms of the gene.

Previous research led by Holland found that some of the QQ newborns may be 50 times more susceptible to chlorpyrifos and chlorpyrifos oxon than RR newborns with high PON1 levels, and 130 to 164 times more susceptible than some of the RR adults.

Of the children in this latest study, 24 percent had the QQ genotype, and 18 percent had the TT genotype, both of which are associated with lower activity of the PON1 enzyme. Moreover, 7.5 percent of the children had both QQ and TT genotypes, which is considered an even more vulnerable profile.

On average, the quantity of enzyme quadrupled between birth and age 7. The greatest rise in enzyme activity was among children with the RR and CC variants of the PON1 gene, which quickly outpaced the increase in children with the QQ and TT genotypes.

The fact that enzyme activity remained low for certain kids with vulnerable genotypes well past age 2 was surprising for the study authors. The researchers are continuing to collect data for these children as they grow older to see if the pesticide susceptibility continues.

“In addition to its involvement in the metabolism of pesticides, many studies are now finding that PON1 may play an important role in protecting against oxidative stress, which is linked to diseases from asthma to obesity and cardiovascular disease,” said study lead author Karen Huen, a UC Berkeley Ph.D. student in environmental health sciences. “The children in our study whose genotypes are related to lower PON1 activity may not only be more susceptible to pesticides throughout much of their childhood, they may also be more vulnerable to other common diseases related to oxidative stress.”

Notably, other studies have found that PON1 genotypes vary by race and ethnicity, with the Q variants more common among Caucasians, less common among Latinos, and least common among African Americans. The majority of the subjects in this study were Mexican-American.

“What’s important about this study is that it shows that young children are potentially susceptible to certain organophosphates for a longer period of time than previously thought,” said Brenda Eskenazi, UC Berkeley professor of epidemiology and director of CHAMACOS and the Center for Children’s Environmental Health Research. “Policymakers need to consider these vulnerable populations when establishing acceptable levels of exposure to different pesticides.”

Funding from the National Institute of Environmental Health Sciences and the EPA helped support this research.

Reference: UC Berkeley, Children susceptible to pesticides longer than expected, study finds, June 22, 2009

Tobacco is an important cash crop of Pakistan. Pesticides are commonly used to increase the crop yield, but their health impact has not been studied yet.  

The objectives of the study were to determine the frequency of pesticide poisoning and to explore the knowledge, attitudes and practices (KAP) towards safety measures among the tobacco farmers in Swabi, Pakistan.  

One hundred and five tobacco farmers involved in pesticide application were randomly selected from two villages of district Swabi. A structured questionnaire was used for clinical and KAP information. Plasma cholinesterase (PChE) levels were measured by Ellman’s method by using GD Italy kits. All tobacco farmers were males with a mean (SD) age of 26 (9) years.  

The majority of the farmers reported multiple symptoms headache, dizziness, vomiting, shortness of breath, muscle weakness and skin rash correlate with the clinically significant depression of PChE levels. 

Out of 105 pesticide applicators, 58 (55%) had post-exposure reduction in PChE levels <20% from baseline, 35 (33%) had mild poisoning (20-40% reduction) and 12 (11%) had moderate poisoning (>40% reduction).  

Most of the farmers did not use any personal protective equipment during pesticide handling. Only a few used shoes (31%), masks (14%) and gloves (9%) during pesticide spray.  

In conclusion, the tobacco farmers had mild to moderate pesticide poisoning, which was correlated with depression in PChE levels. Moreover, most farmers had little knowledge about the safety measures, casual attitude and unsatisfactory safety practices with regard to the use of basic protective equipments during pesticide applications on the tobacco crop. 

Reference: Khan DA, Shabbir S, Majid M, Naqvi TA, Khan FA., Risk assessment of pesticide exposure on health of Pakistani tobacco farmers, aDepartment of Pathology, Army Medical College, NUST, Rawalpindi, Pakistan, Journal of Exposure Science and Environmental Epidemiology advance online publication, 17 June 2009; doi:10.1038/jes.2009.13.

Searchable database shows pesticide residues still common

San Francisco, June 17, 2009 — Ever wonder about pesticides on your food? Or in your drinking water? In particular, which of those pesticides are most hazardous? A new tool from the nonprofit group Pesticide Action Network sheds new science-driven light on the invisible problem of pesticide residues.
 
Today’s launch of the What’s on My Food? database makes the results of government tests for pesticide residues in food available online in a searchable, easy-to-use format. The database shows what pesticides are found on each food, in what amount, and – for the first time – links those residues to the health effects associated with exposure to each of the chemicals.
 
“This kind of public visibility around pesticides is particularly needed in the U.S.,  since regulators base their decisions on toxicology studies that are almost all done by industry,” explains Dr. Brian Hill, Senior Scientist with Pesticide Action Network and the primary developer of the What’s on My Food? database. “Nearly 900 million pounds of pesticides are used in the U.S. every year, yet regulations depend on studies that are not peer-reviewed and are kept hidden behind the veil of ‘confidential business information.’” Hill notes that the 900 million figure is long overdue for updating, as the most recent pesticide use figures from the Environmental Protection Agency are for 2001.
 
In addition to highlighting the potential direct health effects of pesticide residues, the What’s on My Food? database points to the many problems associated with pesticide use before food reaches the kitchen table. Widespread use of agricultural chemicals threatens the health of workers and those in nearby communities and schools, as well as harming wildlife and contaminating ecosystems, according to the site.
 
“It’s time to shift away from reliance on these dangerous chemicals,” says Kathryn Gilje, Pesticide Action Network’s Executive Director. “In Europe governments have recognized that a healthy population and clean environment are worth more than short-term industry profits. They are moving toward safer and healthier ways to produce food, and we need to do the same.”
 
In the Take Action section of the site, Pesticide Action Network calls on consumers not only to vote with their dollars by choosing organic foods whenever possible, but also to become involved as “food citizens” demanding a clean, green and fair food production system.
 
Launch of the new database coincides with the release of Food, Inc., a film by the producers of An Inconvenient Truth that documents the dangerous health and environmental impacts of industrialized food production. Food reporter Michael Pollan calls Food, Inc. “the most important and powerful film about our food system in a generation.”
 

Reference: Pesticide Action Network North America, Searchable database shows pesticide residues still common, June 18, 2009

Resources:

• What’s On My Food? Database
• U.S. Department of Agriculture site re: food residue testing
• Food, Inc. “Hungry for Change” interactive cafeteria featuring WhatsOnMyFood? Database