(Beyond Pesticides, September, 15, 2009) On September 11, 2009, the Environmental Protection Agency (EPA) announced plans to place additional limitations on the use of three organophosphate pesticides ”” chlorpyrifos, diazinon and malathion ”” to protect endangered and threatened salmon and steelhead in California, Idaho, Oregon and Washington. The announcement comes in response to a series of lawsuits brought by Pacific Coast Federation of Fishermen’s Associations (PCFFA), the Northwest Coalition for Alternatives to Pesticides, and other salmon advocates, with legal representation from Earthjustice, aimed at removing toxic pesticides from salmon spawning streams throughout the northwest. In response to the litigation, the National Marine Fisheries Service (NMFS) in November of 2008 released a “biological opinion” that set forth a plan for protecting Pacific salmon and steelhead from three toxic organophosphate pesticides. That decision came after almost a decade of legal wrangling between salmon advocates led by Earthjustice and the federal government. The biological opinion prescribed measures necessary to keep these pesticides out of water and to protect salmon populations in Washington, Oregon, California, and Idaho. The announcement from EPA moves this work forward. Although the experts at NMFS recommended prohibiting aerial applications of the three pesticides within 1,000 feet of salmon waters […]

(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 23, 2009) A new study published in the August 2009 issue of Environmental Toxicology and Chemistry found that insecticides used in highly populated agricultural areas of California’s Central Valley affect amphibians that breed in the Sierra Nevada Mountains to the east. This study adds to the increasing evidence that pesticides impact areas and wildlife species that are miles from sources of pesticide application. Researchers from the Cooperative Wildlife Research Laboratory, Southern Illinois University and U.S. Geological Survey (USGS) examined the chronic toxicity of two of the insecticides most commonly used in the Central Valley- chlorpyrifos and endosulfan, to larval Pacific treefrogs (Pseudacris regilla) and foothill yellow-legged frogs (Rana boylii), the amphibians with declining populations that live and breed in meadows surrounding the Sierra Nevada. The results are discussed in “Toxicity of Two Insecticides to California, USA, Anurans and Its Relevance to Declining Amphibian Populations.” The study used laboratory testing to examine how the insecticides affected the two frogs at environmentally realistic concentrations. During testing, tadpoles were observed at various stages of development to see how the insecticides affected their growth and health. The researchers found that endosulfan was more toxic than chlorpyrifos to both species, and tadpoles […]

(Beyond Pesticides, July 6, 2009) Last week, the U.S. Environmental Protection Agency (EPA) proposed to formally evaluate the harmful effects of 74 pesticides on 11 endangered and threatened species in the San Francisco Bay Area over the next five years, and to impose interim restrictions on use of these pesticides in and adjacent to endangered species habitats. The proposal stems from a settlement agreement with the Center for Biological Diversity, which sued EPA in 2007 for violating the Endangered Species Act by registering and allowing the use of toxic pesticides in Bay Area endangered species habitats without determining whether the chemicals jeopardize those species’ existence. “Tens of millions of pounds of toxic and poisonous chemicals, known to be deadly to endangered species and harmful to human health, including proven carcinogens and endocrine disruptors, are applied in the Bay Area each year, and many of those find their way through runoff or drift into our soil, creeks and rivers, San Francisco Bay, and sensitive wildlife habitats,” said Jeff Miller, conservation advocate with the Center. “The toxic stew of pesticides in the Bay-Delta has played a major role in the collapse of native fish populations, and pesticides are a leading cause of […]

(Beyond Pesticides, June 25, 2009) 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 two, but instead, the UC Berkeley researchers found that the enzyme level remained low in some individuals through age seven. Based upon the findings, reported 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 three to five times more susceptible than adults, and for other pesticides the standards assume no difference,” said Nina Holland, Ph.D., 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 […]

(Beyond Pesticides, June 17, 2009) A new study finds that toxic pesticides, including those already banned, persist in homes. The study’s results indicate that most floors in occupied homes in the U.S. have measurable levels of insecticides that serve as sources of exposure to home dwellers. These persistent residues continue to expose people, especially vulnerable children, to the health risks associated with these chemicals. Published in Environmental Science and Technology, the study, entitled “American Healthy Homes Survey: A National Study of Residential Pesticides Measured from Floor Wipes,” was conducted as a collaboration between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Housing and Urban Development. Five hundred randomly selected homes were sampled using alcohol wipes to collect dust from hard surface floors, mostly kitchen floor surfaces. The swipes were analyzed for 24 currently and previously use residential insecticides in the organochlorine, organophosphate, pyrethroid and phenylpyrazole classes, and the insecticide synergist piperonyl butoxide. Researchers found that currently used pyrethroid pesticides were, not surprisingly, at the highest levels with varied concentrations. Fipronil and permethrin, both currently used, were found in 40 percent and 89 percent of homes respectively. However, the researchers found that long discontinued pesticides like DDT and […]

(Beyond Pesticides, May 19, 2009) Nearly six months after federal scientists began issuing restrictions to protect salmon and steelhead in the Pacific Northwest and California, the U.S. Environmental Protection Agency (EPA) has yet to take even the first step toward implementing these protections. This delay follows almost a decade of legal wrangling in which a coalition of environmental and fishing groups, led by the non-profit public interest law firm Earthjustice, won a court order. Tell EPA to stop its foot-dragging and protect salmon and steelhead from toxic pesticides. The six pesticides that scientists have reviewed so far are some of the most dangerous chemicals used today. All six””chlorpyrifos, diazinon, malathion, carbaryl, carbofuran, and methomyl””are neurotoxic and pose serious risks to both humans and wildlife. While many of these pesticides have been phased out for residential use, they continue to expose wildlife and farmworkers through their use in agriculture. Thirty-one more chemicals will undergo review by scientists at the National Marine Fisheries Service (NMFS) in the next three years. The new restrictions require EPA to prohibit application of the six pesticides in or near salmon and steelhead habitat. They also require EPA to prohibit application when the weather may cause the […]

(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 […]

(Beyond Pesticides, December 16, 2008) According to a new study, published in the December 2008 issue of Environmental Health Perspectives by researchers at Columbia University’s Mailman School of Public Health, pregnant women continue to be exposed to pesticides in the home. In fact, 75% of the sampled homes of pregnant women in inner-city New York are contaminated with piperonyl butoxide (PBO), a pesticide synergist linked to cancer and other health problems. Following the Environmental Protection Agency’s phase-out agreements with the manufacturers of organophosphate insecticides chlorpyrifos and diazinon in 2000 and 2001, the Columbia University researchers sought to determine the impact of the new regulations on pest infestation levels, pesticide use, and pesticides measured in indoor air samples. They enrolled 511 pregnant women from inner-city New York between 2000 and 2006. Permethrin, a pyrethroid insecticide; PBO, a pyrethroid synergist; chlorpyrifos; and diazinon were measured in 48-hr prenatal personal air samples. Data on pest infestation and pesticide use were collected via questionnaire. 88% of women report using pesticides during pregnancy and 55% report using higher-exposure pesticide applications (spray cans, pest bombs and/or professional pesticide applicators). Self-reported pest sightings and use of higher-exposure applications increased significantly after the regulations were implemented. PBO, cis-, […]

(Beyond Pesticides, December 10, 2008) Most families don’t realize that they might be bringing more than holiday cheer into their homes this Christmas season. Families celebrating this holiday season with the time-honored tradition of a Christmas tree can choose to go green and avoid the toxic chemicals that are typically used to grow it. Beyond Pesticides recently launched a Christmas Trees and Pesticides web page to help inform consumers this holiday season. Of the pesticides that the Environmental Protection Agency (EPA) has registered for use on Christmas trees, most are linked to one or more adverse effects, including cancer, hormonal disruption, neurotoxicity, organ damage, reproductive/birth defects, asthma, environmental effects and more. Their use results in exposure to workers, wildlife, and waterways. Beyond Pesticides has compiled a list of 25 pesticides commonly used or recommended for use by state agricultural extension services, including: 2,4-D, bifenthrin, chlorpyrifos, diazinon, esfenvalerate, glyphosate, simazine and more. Oregon, North Carolina, Michigan, Pennsylvania, Wisconsin, Washington, New York, and Virginia are the nation’s top Christmas tree producing states, and together account for more than half of the trees grown in the U.S. The Cooperative Extension Service of North Carolina reports that glyphosate -a pesticide linked to increased risk […]

(Beyond Pesticides, December 8, 2008) A new study by a National Institute for Occupational Safety and Health (NIOSH) researcher finds the pesticide poisoning incidence rate among U.S. agricultural workers is thirty-nine times higher than the incidence rate found in all other industries combined. The study, “Acute Pesticide Poisoning Among Agricultural Workers in the United Sates, 1998-2005,” published in the December issue of the American Journal of Industrial Medicine, is believed to be the first detailed multi-state assessment of acute pesticide poisonings among agricultural workers. From 1998 to 2005, a total of 3,271 cases of acute occupational pesticide-related illness/injury among agricultural workers were identified in ten states. According to EPA, the Worker Protection Standards are designed to reduce the risk of injury or illness to agricultural field workers resulting from exposure to pesticides. Although the WPS was expanded in 1995 and in 2005 EPA developed a new WPS How to Comply (HTC) Manual, the NIOSH findings indicate that agricultural workers continue to have an elevated risk for acute pesticide poisoning. Furthermore, female agricultural workers experienced nearly twice the risk of pesticide poisoning of male agricultural workers. The most common factors that contributed to pesticide exposure included off-target drift, early reentry into […]

(Beyond Pesticides, November 17, 2008) A toxic soup of the most commonly used pesticides frequently detected in nature can adversely affect the environment and decimate amphibian populations even if the concentration of the individual chemicals are within limits considered safe, according to University of Pittsburgh research published in the online edition of Oecologia. The results of this study build on a nine-year effort to understand potential links between the global decline in amphibians, routine pesticide use, and the possible threat to humans in the future. Amphibians are considered an environmental indicator species because of their unique sensitivity to pollutants. Their demise from pesticide exposure could foreshadow the fate of less sensitive animals, according to study author Dr. Rick Relyea, Ph.D., an associate professor of biological sciences in the University of Pittsburgh’s School of Arts and Sciences. Leopard frogs, in particular, are vulnerable to contamination; once plentiful across North America, their population has declined in recent years as pollution and deforestation has increased. Dr. Relyea exposed gray tree frog and leopard frog tadpoles to small amounts of the ten pesticides that are widely used throughout the world. Dr. Relyea selected five insecticides: carbaryl, chlorpyrifos, diazinon, endosulfan, and malathion; and five herbicides: […]

(Beyond Pesticides, October 6, 2008) University of Pittsburgh researchers have found that the commonly used insecticide malathion can decimate tadpole populations by altering their food chain. The study, published in the October 1 edition of Ecological Applications, finds that gradual amounts of malathion that were too small to directly kill developing leopard frog tadpoles instead sparked a biological chain of events that deprived them of their primary food source. As a result, nearly half the tadpoles in the experiment did not reach maturity and would have died in nature. The results build on a nine-year effort to investigate whether there is a link between pesticides and the global decline in amphibians, which are considered an environmental indicator species because of their sensitivity to pollutants. According to the researchers, their deaths may foreshadow the poisoning of other less environmentally-sensitivespecies, including humans. According to the U.S. Environmental Protection Agency (EPA), malathion is the most commonly used insecticide in U.S. agriculture and the third most commonly used insecticide in the U.S. home and garden sector. It has been detected in the wetlands where frogs and other amphibians live. The researchers created simulated ponds from 300-gallon outdoor tanks containing wood frog and leopard frog […]

(Beyond Pesticides, October 1, 2008) Last week, a jury awarded $1 million in compensation to an organic farm in Santa Cruz, California, whose herbs were contaminated by pesticides. The jury found that organophosphate pesticides, used on vegetables on neighboring farms, drifted onto the organic farm, leaving the herbs in violation of organic standards. The organic farm, Jacobs Farm Del Cabo, filed a lawsuit against the pesticide application company Western Farm Service, Inc. in May 2007. The suit sought an order to stop Western Farm Service from spraying pesticides that contaminate crops at Wilder Ranch State Park, where Jacobs Farm leases 120 acres. Compensation for losses, in the sum of $1 million, which resulted from pesticide contamination, was also sought. The court ruled that pesticide applications by Western Farm Service resulted in trespass of the pesticides onto Jacobs Farm and were legally determined to be a nuisance depriving Jacobs Farm of the right to use and enjoy the land, caused by negligence on the part of Western Farm Services. The jury found that Jacobs Farm was damaged in the sum of $1 million and Judge Robert Atack ordered judgment in that amount against Western Farm Service. The organophosphates, chlorpyrifos, diazinon, and […]

(Beyond Pesticides, September 10, 2008) Following the report released by the National Marine Fisheries Service that identified 37 pesticides that pose risks to salmon and steelhead, Oregon state officials are moving ahead to set new safety benchmarks for seven pesticides of priority concern. A team from the Oregon Water Quality Pesticide Management Program identified seven priority hazardous pesticides: azinphos-methyl, chlorpyrifos, dacthal, diazinon, endosulfan, simazine and ethoprop, based on water-quality monitoring in five Oregon watersheds, including the Pudding River near Salem, as well as the Clackamas, Yamhill, Hood and Walla Walla watersheds. Three pesticides, azinphos-methyl, diazinon and chlorpyrifos have been detected at concentrations that exceed federal aquatic criteria in the Clackamas River Basin (See report here). Chlorpyrifos was detected at maximum levels more than twice the federal standard. The National Marine Fisheries Service report on the ecological damage associated with pesticide use reveals “overwhelming evidence” to suggest that 37 pesticides, including these seven, increase the chance of extinction for protected salmon and steelhead. The state is now turning to its own team of experts to set stringent benchmarks based on existing research on these chemicals of concern. Generally the U.S. Environmental Protection Agency (EPA) is charged with developing water quality standards […]

(Beyond Pesticides, August 19, 2008) Three toxic pesticides used heavily in the United States ”” chlorpyrifos, diazinon, and malathion ”” harm children and farmworkers, poison wildlife, and taint food and drinking water, and despite well-documented hazards, the Environmental Protection Agency (EPA) allows homeowners, farmers and others to use these poisons in ways that harm salmon and steelhead. Coupled with public pressure, a recent scientific analysis from the National Marine Fisheries Service (NMFS) could force EPA to adopt new restrictions on the use of these pesticides in the Pacific Northwest and California. In a draft study — called a “biological opinion” — released on July 31, 2008, NMFS concluded that chlorpyrifos, diazinon, and malathion are contaminating rivers and streams jeopardizing protected salmon and steelhead. Please urge NMFS and EPA to adopt strong measures to protect Pacific salmon from these poisons. It is their responsibility under the Endangered Species Act. Please send an email addressed to both: Jim Lecky Director of Office of Protected Resources, NMFS [email protected] James Gulliford Assistant Administrator, US EPA Headquarters [email protected] You can be sure that chemical companies are working to ensure the unabated use of their products. Make sure the voice of the public is heard. Harmful […]

(Beyond Pesticides, August 14, 2008) The first report released by the National Marine Fisheries Service (NMFS) as a result of a lawsuit (NCAP et al. v. NMFS, No. 07-1791 RSL) settlement reveal “overwhelming evidence” to suggest that the pesticides chlorpyrifos, malathion, and diazinon increase the chance of extinction for protected salmon and steelhead. The report on the three pesticides and their effects on threatened fish is the first in what is expected to be a four year review process of 37 pesticides. “These are pesticides that EPA [the Environmental Protection Agency] has swept under the rug for years. These are three that stood out as the nastiest of the (pesticides) that are still in widespread use,” said Joshua Osborne-Klein, an attorney for Earthjustice who represented the plaintiff, Northwest Coalition for Alternatives to Pesticides (NCAP). The 377-page report is clear in its conclusion that current use patterns of these three toxic pesticides threaten the salmon and steelhead protected by the Endangered Species Act, but it does not delineate the next steps to reduce the risk. A report on mitigation measures, which could include restrictions or bans, is expected in the next few months. The timing of the report coincides with other […]

(Beyond Pesticides, June 20, 2008) University of Massachusetts (UMass) researchers have identified certain plants that can absorb excess pesticides from soil and prevent their runoff into adjacent waterways. Golf courses typically use considerable amounts of herbicides and fungicides to maintain perfectly manicured greens, much of which ends up polluting water and harming aquatic organisms. This study found that plants like blue flag iris can act as “living filters” on the edge of greens.“ Studies from golf greens have shown that five percent to ten percent of the total pesticides applied are lost in runoff. In worst case conditions, this figure can be as high as 30 percent,” says John Clark, Ph.D., a professor of veterinary and animal science and a principal investigator on the grant. “We have identified plant species that can reduce the amount of certain pesticides in soil by up to 94 percent in the greenhouse.” Blue flag iris reduced chlorpyrifos by 76 percent and levels of chlorothalonil by 94 percent after three months of growth. The study was funded by the UMass Amherst Environmental Institute, the Massachusetts Pesticide Analysis Laboratory, and the U.S. Golf Association. Interest in “greener” turf management practices have risen lately along with golf’s […]

(Beyond Pesticides, March 24, 2008) Scientists at the U.S. Geological Survey (USGS) announced that they have identified ten contaminants, including pesticides, in the Potomac River, which flows through downtown Washington, DC, that could be responsible for the alarming discovery of “intersex fish,” male fish producing eggs. The suspected chemicals include: atrazine, a common herbicide used in agriculture and on lawns that is already linked to sexual abnormalities in frogs; insecticides chlorpyrifos and endosulfan; the herbicide metolachlor; and two chemicals used to add fragrance to perfumes, soaps and other products, tonalide and galaxolide. To collect the samples, USGS scientists suspended a device intended to serve as a facsimile fish in the Potomac River near the Washington, DC’s Blue Plains sewage plant. The device had a plastic-coated tube, which simulated a fish’s permeable skin, and a layer of simulated fat. According to the Washington Post, the tests on this fake fat revealed a range of potentially worrisome pollutants. Most have been found in other streams around the U.S. “The types of things we’re finding are the types of things that are associated with everyday life,” David Alvarez, a U.S. Geological Survey research chemist who analyzed samples from the Potomac told the Washington […]

(Beyond Pesticides, March 20, 2008) A 2000-2005 U.S. Geological Survey (USGS) study, Pesticide Occurrence and Distribution in the Lower Clackamas River Basin, Oregon, 2000-2005, finds a variety of pesticides in river and tributary samples, along with trace-level detections of pesticides in treated drinking-water samples collected from a drinking-water treatment plant that uses the Clackamas River as a raw-water source. While the federal government is quick to point out that detections in drinking water are below existing Environmental Protection Agency (EPA) drinking-water standards and most river samples are below the agency’s aquatic life benchmarks, studies show hazardous endocrine-disrupting and immunosuppressive effects at extremely low levels — far below EPA standards. A total of 63 pesticide compounds were detected in 119 water samples collected during storm and non-storm conditions using low-level detection methods. More pesticides were detected in the tributaries than in the Clackamas River mainstem. One or more of 15 pesticides were detected in nine of 15 samples of drinking water. Environmental and public health advocates are concerned that these results add to a pattern of contamination across the country. USGS data released in 2008, shows widespread pesticide contamination in the Chesapeake Bay watershed, and a 2004 USGS report of nationwide […]

(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 […]

(Beyond Pesticides, March 11, 2008) A Decade of Children’s Health Research: Highlights from EPA’s Science to Achieve Results Program, a ten-year Environmental Protection Agency (EPA) study released March 10, 2008, summarizes important research findings found from $127 million invested in research grants on children’s environmental health in response to an executive order issued in 1997. Executive Order 13045, Protection of Children From Environmental Health Risks and Safety Risks, requires federal agencies to place a high priority on assessing risks to children. EPA, through its Science to Achieve Results (STAR) program, issued more than 60 research grants in response to this order, which in turn, produced more than 1000 scientific journal articles. “Understanding potential environmental health risks to children is important to EPA,” said George Gray, assistant administrator of EPA’s Office of Research and Development. “This research will help us assess and address environmental factors that may affect some of the most vulnerable members of our society.” The report summarizes research from the STAR children’s health program over the past 10 years, highlighting scientific findings in epidemiology, exposure science, genetics, community-based participatory research, interventions, statistics and methods. Some of the major findings of this research include: People metabolize pesticides differently based […]

(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. […]