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New, Inexpensive “Dipstick” Can Test for Pesticides in Food

Thursday, November 12th, 2009

(Beyond Pesticides, November 12, 2009) Scientists from McMaster University in Hamilton, Ontario have developed a dipstick test that can detect minute amounts of toxins and pesticides in foodstuffs that is slated to be less costly than current pesticide testing methods and can produce results within minutes. Their paper-strip test produces results in minutes rather than hours by means of an easy-to-read color-change. Published in the November 1 issue of the American Chemical Society’s Analytical Chemistry, a semi-monthly journal: “Reagentless Bidirectional Lateral Flow Bioactive Paper Sensors for Detection of Pesticides in Beverage and Food Samples,” study author, John Brennan, PhD, and colleagues note that conventional tests for detecting pesticides tend to use expensive and complex equipment and in some cases can take several hours to produce results. They cite a growing need for cheaper, more convenient, and more eco-friendly tests for pesticides, particularly in the food industry. A 10 cm-long bioactive paper-based solid-phase biosensor was developed to detect acetylcholinesterase (AChE) inhibitors, including organophosphate pesticides. The researchers tested this sensor using food and beverage samples intentionally contaminated with common pesticides. The strip accurately detected trace amounts of the chemicals within five minutes, according to the scientists. The test strip changes color shades […]

Posted in Uncategorized | 4 Comments »

Study Finds that Mosquito Repellent DEET Affects Nervous System

Wednesday, August 12th, 2009

(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 […]

Posted in Alternatives/Organics, Chemicals, DEET, Disease/Health Effects, Gulf War Syndrome, Nervous System Effects | 5 Comments »

Pesticides in Combination Shown to Increase Endangered Salmon Threat

Thursday, March 5th, 2009

(Beyond Pesticides, March 5, 2009) A new study published in the March 2009 issue of Environmental Health Perspectives finds that pesticide combinations cause more harm to endangered salmon than ndividual pesticide exposure. This means that single-pesticide risk assessments required by the Environmental Protection Agency (EPA) inadequately assess hazards. Mixtures of organophosphate and carbamate pesticides are commonly detected in freshwater habitats that support threatened and endangered species of Pacific salmon. According to the researchers from the National Oceanic and Atmospheric Administration (NOAA) Fisheries and Washington State University, these pesticides inhibit the activity of acetylcholinesterase (AChE) and thus have potential to interfere with behaviors that may be essential for salmon survival. The researchers measured brain AChE inhibition in juvenile coho salmon exposed to sublethal concentrations of the organophosphates diazinon, malathion, and chlorpyrifos, as well as the carbamates carbaryl and carbofuran. The pesticides were tested individually and in combination. They plotted AChE levels on a curve to determine whether the toxicologic responses to binary mixtures were additive, antagonistic (lesser than additive) effect, or synergistic (greater than additive). The authors observed addition and synergism, with a greater degree of synergism at higher exposure concentrations. Several combinations of organophosphates were lethal at concentrations that were […]

Posted in Chemicals, Chlorpyrifos, Diazinon, Malathion, Water, Wildlife/Endangered Sp. | No Comments »

Study Shows Real-World Pesticide Mixtures Harm Salmon

Tuesday, June 10th, 2008

(Beyond Pesticides, June 10, 2008) According to scientists at Simon Fraser University in British Columbia, Canada, real-world pesticide combinations, such as those found in Canada’s Nicomekl River, may contribute to latest decline in the region’s endangered salmon populations. The study, published in Environmental Science and Technology (ES&T), a publication of the American Chemical Society, examines the impact by simulating the river’s low-level pesticide mixture to examine its effects on fish. The study used steelhead trout, a member of the salmon family, and found that the pesticide mix can deaden the trout’s sense of smell. This could harm the fish’s ability to avoid predators, find mates, and migrate back to sea, the researchers say, and could contribute to the threatened and endangered status of salmon species. “Most laboratory studies examine the effects of a single chemical, often at high concentrations, but real-world streams contain a mixture of chemicals at very low concentrations,” Keith Tierney, Ph.D., the study’s coauthor, told ES&T. Dr. Tierney and his colleagues re-created river water in the laboratory under controlled conditions with carefully measured levels of the 10 most frequently occurring pesticides in British Columbia’s Nicomekl River. The mixture contained four major classes of pesticides, including the commonly […]

Posted in Atrazine, Chemicals, Diazinon, Water, Wildlife/Endangered Sp. | No Comments »

Chemical Exposure Linked to Gulf War Veterans’ Illness

Thursday, March 13th, 2008

(Beyond Pesticides, March 13, 2008) Exposure to certain chemicals, including pesticides and nerve agents, explains the high rates of illness in Persian Gulf War Veterans, according to a new study published in the Proceedings of the National Academy of Sciences. Veterans from the 1990-91 conflict have a higher rate of chronic, multi-symptom health problems than either non-deployed personnel or those deployed elsewhere. Symptoms routinely reported by these veterans include fatigue, muscle or joint pain, memory problems, trouble sleeping, rash and breathing problems. Due to the findings, the study author, Beatrice Golomb, M.D., Ph.D., associate professor of medicine at the University of California, San Diego School of Medicine, warns of the potential risk to civilians exposed to pesticides.“Health issues among Gulf War veterans have been a concern for nearly two decades. Now, enough studies have been conducted, and results shared, to be able to say with considerable confidence that there is a link between chemical exposure and chronic, multi-symptom health problems,” said Dr. Golomb. “Furthermore, the same chemicals affecting Gulf War veterans may be involved in similar cases of unexplained, multi-symptom health problems in the general population.”The study synthesized evidence regarding a class of chemicals known as acetylcholinesterase inhibitors (AchEs), including […]

Posted in Acephate, Aldicarb, Bensulide, Carbaryl, Chemicals, Chlorpyrifos, Diazinon, Dichlorvos, Disease/Health Effects, Fenoxycarb, Gulf War Syndrome, Malathion, Parathion, Propetamphos, Propoxur, Trichlorfon | No Comments »

Pesticide Mixtures Have Greater Effect on Salmon

Wednesday, February 20th, 2008

(Beyond Pesticides, February 20, 2008) Pesticides that run off agricultural land and mix in rivers and streams combine to have a greater than expected toxic effect on the salmon nervous system, according to researcher Nathaniel Scholz, PhD, a zoologist with the National Oceanic and Atmospheric Administration (NOAA) in Seattle. Dr. Scholz, who presented his findings at the symposium entitled From Kitchen Sinks to Ocean Basins: Emerging Chemical Contaminants and Human Health, which was organized by NOAA and hosted at the American Association for the Advancement of Science (AAAS) Annual Meeting, had previously looked at the effects of individual pesticides. However, to get a more realistic idea of exposure, combinations of several pesticides were used and juvenile salmon exposed to them two at a time. The results surprised Dr. Scholz and his team. The total impact observed from combined pesticides was greater than the sum of the individual pesticides, demonstrating a synergistic effect. Some pesticides that were not deadly when tested in individual trials killed all salmon exposed to combinations. A mixture of the pesticides diazinon and malathion, exhibited the greatest synergistic effect and killed all the salmon exposed to them, even at the lowest concentrations. “It was eye opening,” Dr. […]

Posted in Chlorpyrifos, Diazinon, Malathion, Water, Wildlife/Endangered Sp. | No Comments »

Order of Exposure Can Make the Poison

Thursday, July 5th, 2007

(Beyond Pesticides, July 5, 2007) A new study showing that the order of exposure to multiple pesticides may be just as important as the dose, timing and length of exposure adds another dimension to the complex task of risk assessments. Using carbaryl and chlorpyrifos, University of York scientists have observed significant differences in mortality rates of freshwater invertebrates depending on the order of exposure to these frequently used agricultural chemicals. The study, Modeling Combined Effects of Pulsed Exposure to Carbaryl and Chlorpyrifos on Gammarus Pulex, suggests the sequence of pesticide exposure may be just as important of a variable as the dose, the timing of the dose and the length of exposure when factoring environmental and health endpoints. The researchers conducted the study by exposing the freshwater invertebrate Gammarus pulex — a tiny shrimp — to pulses of the two insecticides (both of which affect the nervous system through acetylcholinesterase inhibition) mimicking exposure to chemical mixtures in the environment — for example, farmers may apply several different pesticides over the growing season that run off into the aquatic environment. After receiving a pulse of one pesticide, the shrimp were given 14 days, a time period chosen based on previous experiments, […]

Posted in Carbaryl, Chlorpyrifos, Pesticide Regulation, Water | No Comments »

USGS Finds Common Breakdown Products Are Lethal to Amphibians

Friday, June 1st, 2007

(Beyond Pesticides, June 4, 2007) The breakdown products (oxons) of the three most commonly used organophosphate pesticides in California’s agricultural Central Valley — chlorpyrifos, malathion and diazinon – are 10 – 100 times more toxic to amphibians than their parent compounds, which are already highly toxic to amphibians, according to a study released last Wednesday by scientists of Southern Illinois University, Carbondale, and the U.S. Geological Survey (USGS) Western Ecological Research Center. The results of the laboratory experiments on the toxicity of the three breakdown products were published in the journal Environmental Pollution. The title of the article is “Comparative toxicity of chlorpyrifos, diazinon, malathion and their oxon derivatives to larval Rana boylii.” “Since some of the parent pesticide compounds are already at concentrations sufficient to cause significant amphibian mortality in the Sierra Nevada, the higher toxicity of the breakdown products poses a serious problem,” said Gary Fellers, Ph.D., coauthor of the study. Donald Sparling, Ph.D., a research biologist and contaminants specialist at Southern Illinois University, and Dr. Fellers, a research biologist and amphibian specialist at the USGS Western Ecological Research Center in California, conducted laboratory tests to determine the acute toxicity – the lethal dosage causing death in 96 […]

Posted in Chemicals, Wildlife/Endangered Sp. | No Comments »

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