(Beyond Pesticides, March 1, 2013) In a literature review published in Toxicology last week, researchers found that environmental and occupational pesticide exposure was strongly associated with declines in sperm count. Researchers Sheena Martenies, BS, and Melissa Perry, ScD., MHS., determined that of the 17 studies evaluated, 15 of them reported significant associations between pesticides and semen quality. The researchers counted semen quality according to concentration of sperm over an area, their motility and ability to move, as well as their shapes. Researchers targeted studies on DDT, HCH, and abamectin, grouping pyrethroids and organophosphates by class. What they found was striking: almost all the studies reported a decrease in sperm concentration; decreased motility was also reported though less frequently; while morphological changes were not strongly associated in studies””only two indicated any changes to sperm shape. These findings build on a growing body of evidence that pesticide exposure at environmental or occupational levels diminished sperm health. In addition to the U.S. findings,  studies conducted on French, New Zealander, Indian, Tunisian, and Israeli men have all found decline in sperm count. Some studies record a drop by approximately 50% between 1940 and 1990, no small amount. These results might not be surprising as […]

(Beyond Pesticides, February 8, 2013) A recent study conducted at the University of Granada, Spain and published in the Journal Environmental Research proposes a link between exposure to persistent organic pollutants (POPs) in food, air, and water and prevalence of type 2 diabetes in adults, regardless of age, gender, and body mass index. The paper concludes that people with higher concentrations of DDE, the break down product of DDT, are four times more likely to develop type 2 diabetes compared to other participants in the study. Increased rates of type 2 diabetes are also associated with exposure to beta-hexachlorocyclohexane, a break down product of the toxic chemical lindane, which in still allowed for use in agriculture and certain formulations of products used to treat lice and scabies. The study was carried out by analyzing the concentrations of specific POPs in adipose, or fat, tissue of 386 adults undergoing non-cancer-related surgery in Spain. According to one of the authors of the study, Juan Pedro Arrebola, “Human adipose tissue acts as an energy reservoir and has an important metabolic function. However, adipose tissue can store potentially harmful substances, such as POPs.”    The study found that as concentrations of POPs grows in […]

(Beyond Pesticides, March 21, 2012) A half-century after California officials discovered that large amounts of the pesticide DDT had been discharged into a San Francisco Bay canal, the chemical is still poisoning fish and posing a threat to human health despite numerous cleanup attempts. After years of limited success with clean-up, the U.S. Environmental Protection Agency (EPA) has launched a three-year plan to pinpoint the cause of continuously high DDT levels and engage the surrounding community in cleanup and education efforts. The former plant and the adjacent canal, called the Lauritzen Channel, an inlet of the greater San Francisco bay, is one of the most polluted places in the nation. DDT levels have not decreased in the channel even after numerous dredging and other mitigation measures. In fact concentrations have increased. By 2011, DDT concentrations exceeded 1994 levels and some fish have DDT levels in their tissues hundreds of times higher than their counterparts in the rest of the San Francisco Bay. EPA said earlier this month it is launching a three-year plan to help unravel the mystery of why cleanup attempts are failing, and will work with the city to increase awareness among anglers who rely on bay fish […]

(Beyond Pesticides, February 1, 2012) Pesticides could be suppressing vitamin D levels in people, leading to deficiency and disease, say scientists. This comes from a new study which discovered that adults with high serum concentrations of organochlorine pesticides, such as DDT, have lower vitamin D levels, further proving that these chemicals have a long-lasting impact on human health. While not widely appreciated, some organochlorine pesticides continue to be used in the U.S., resulting in exposure through our diet, environment, and prescription drugs, while most organochlorine pesticides have been banned in the U.S. and much of the world. Exposure to low doses of organochlorine pesticides has been previously linked to common diseases like type 2 diabetes, metabolic syndrome and cardiovascular disease. Vitamin D deficiency has similarly been associated with a rise in chronic diseases, but the two have been studied separately by researchers in different fields. The study, “Associations between Organochlorine Pesticides and Vitamin D Deficiency in the U.S. Population,” compared serum concentrations of organochlorine (OC) pesticides with serum concentrations of 25-hydroxyvitamin D (25(OH)D), a vitamin D pre-hormone, which is used to assess vitamin D levels in the body. It concludes that background exposure to some OC pesticides can lead to […]

(Beyond Pesticides, November 15, 2011) Research published in the online edition of Environmental Health Perspectives finds that exposure to certain pesticides elevates the risk of non-Hodgkin’s Lymphoma (NHL). The study, “A Prospective Study of Organochlorines in Adipose Tissue and Risk of non-Hodgkin’s Lymphoma,” finds a positive correlation between levels of the organochlorine pesticides DDT, cis-nonachlor, chlordane, and their breakdown products in human fat tissue and the often deadly form of cancer. The researchers from the Danish Cancer Society’s Institute of Cancer Epidemiology conducted a case-cohort study using a prospective Danish cohort of 57,053 persons enrolled between 1993 and 1997. Within the cohort they identified 256 persons diagnosed with NHL in the population-based nationwide Danish Cancer Registry and randomly selected 256 sub-cohort persons. The research team measured concentrations of eight pesticides and ten polychlorinated biphenyl congeners (PCBs) in fat tissue collected upon enrollment. The results indicate a higher risk of NHL in association with higher fat tissue levels of DDT, cis-nonachlor and oxychlordane, but shows no association with PCBs. Because the tissue samples were taken up to 15 years prior to the cancer diagnosis, the research suggests that exposure to these organochlorines increases the risk of NHL later in life and […]

(Beyond Pesticides, October 14, 2011) Researchers at Uppsala University in Sweden have found that environmental toxicants such as dioxins, PCBs, and pesticides can pose a risk for cardiovascular disease. The results of the study, entitled “Circulating Levels of Persistent Organic Pollutants (POPs) and Carotid Atherosclerosis in the Elderly,” show a link between exposure to persistent organic pollutants (POPs), including several organochlorine pesticides, and the development of atherosclerosis, which can lead to heart disease. The study will be published in the journal Environmental Health Perspectives, and a version of it is available online ahead of print. Cardiovascular diseases, including heart attacks and strokes, are the most common cause of death in industrialized countries, and the most important underlying cause of these diseases is atherosclerosis. Unbalanced blood fats, diabetes, smoking, and high blood pressure are traditionally recognized risk factors for atherosclerosis. Previous studies have also reported possible links between cardiovascular disease and high levels of persistent (long-lived and hard-to-degrade) organic environmental toxicants, such as dioxins, polychlorinated biphenyls (PCBs), and pesticides. These compounds are fat-soluble and can therefore accumulate in vessel walls. However, no earlier studies have investigated possible links between exposure to these compounds and atherosclerosis. Of the POPs that were screened […]

(Beyond Pesticides, July 25, 2011) Exposure to certain pesticides and polycyclic aromatic hydrocarbons (PAHs) in the womb has been linked to neural tube defects, which lead to conditions such as spina bifida, according to researchers at Peking University in China. The study finds elevated levels of the organochlorine pesticides DDT, alpha-hexachlorocyclohexane (a lindane contaminant) and endosulfan, as well as PAHs in the placentas of women who had babies or aborted fetuses with such birth defects. The study, “Association of selected persistent organic pollutants in the placenta with the risk of neural tube defects,” was published July 8, 2011 in the online edition of the Proceedings of the National Academy of Sciences. While most organochlorine pesticides are banned or restricted, they still continue to cause problems decades after their widespread use has ended. This study reinforces the need for a more precautionary approach to regulating pesticides and industrial chemicals. Once released into the environment, many chemicals can affect health for generations, either through persistence or genetic means. PAHs are a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. PAHs are usually […]

(Beyond Pesticides, June 20, 2011) In a study published this week in the journal Pediatrics, researchers report findings that link mothers’ exposure to organochlorine pesticides during pregnancy with infants’ sizes at birth. The trend shows that the more mothers are exposed to the pesticides during pregnancy, the higher the chances are for reduced birth weight and length of their newborns. Comprising a total of 494 women and infants in Valencia, Spain from the years 2003-2006, the study evaluates umbilical cord blood for residues of four pesticides or pesticide degradates: DDT, DDE, hexachlorobenzene (HCB), and beta-hexachlorocyclohexane. The results show that a 10-fold increase in pesticide concentrations in the blood corresponds to a reduction in birth weight of 2-4 ounces. Additional results are correlated to specific pesticides. Higher concentrations of DDT results in a reduction in head circumference of 0.26cm, which the researchers call a “significant decrease.” Additionally, a decrease of 0.39cm in birth length is correlated with each 10-fold increase in concentration of HCB. The researchers note several concerns related to the findings, aside from the results themselves. Since people are exposed to a wide variety of chemicals in general throughout their everyday lives, higher pesticide exposure could betray higher exposure […]

(Beyond Pesticides, June 25, 2010) Two new studies published in the journal Environmental Science and Technology confirm that the majority of toxic contamination threatening national parks originates from agricultural pesticides and industrial operations. In one study an international group of scientists conducted research from 2003-2005 and detected elevated concentrations of various dangerous pesticides in all eight of the national parks and preserves. The other study collected samples of air, water, snow, sediment, lichens, conifer needles, and fish at remote alpine, subarctic, and arctic sites. Researchers found that these samples contained four current-use pesticides including dacthal (DCPA), chlorpyrifos, endosulfans, and y-hexachlorocyclohexane (HGH) as well as four historic-use pesticides including dieldrin, a-HCH, chlordanes, and hexachlorobenzene (HCB). Pesticide concentrations in snow are highest in Sequoia, Kings Canyon, Rocky Mountain and Glacier National Parks. Concentrations in vegetation are mostly dominated by endosulfan and dacthal, and are highest in Yosemite, Kings Canyon, Glacier, and Great Sand Dunes National Park and Preserve. Fish samples also show elevated concentrations of dieldrin and DDT (one of the first pesticides to be banned in 1972 because of Rachel Carson’s Silent Spring). Cold temperatures in alpine or arctic ecosystems tend to concentrate pesticides, which can also bioaccumulate in the local […]

(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, April 16, 2010) Every day, children still die of malaria, a devastating disease that is both preventable and curable. In 2009, the United Nations Environment Program (UNEP) and the World Health Organization (WHO) announced a renewed international effort to combat malaria with an incremental reduction of the reliance on the synthetic pesticide DDT. However, efforts to invest in real solutions are often derailed by those promoting DDT as a “silver bullet” for malaria prevention. Tell President Obama that the President’s Malaria Initiative must invest in safe solutions to malaria, not increase reliance on DDT. Sign by April 22nd and you will be included in the petition to mark World Malaria Day. Sign the petition here. DDT, or dichloro diphenyl trichloroethane, while highly persistent in the environment, was initially found to be effective against mosquitoes and the diseases they carry, such as malaria. However, insect resistance to the chemical has been documented since 1946. DDT was banned in the U.S. in 1972 after it was linked to the decline of the bald eagle and other raptors, and it continues to be linked to health problems. A 2007 study finds that women who were exposed to DDT before the age […]

(Beyond Pesticides, July 27, 2009) A mother’s exposure to urban air pollutants known as polycyclic aromatic hydrocarbons (PAHs) can adversely affect a child’s intelligence quotient or IQ, according to the new study “Prenatal Airborne Polycyclic Aromatic Hydrocarbon Exposure and Child IQ at Age 5 Years.” PAHs are widespread in urban environments and throughout the world as they have many sources, several of which are related to pesticides, including creosote used for wood preservation, burning pesticide-laden grass seed fields, and exposure to organochlorine pesticides whether banned, yet ubiquitous DDT or the still used insecticide dicofol. Other sources include synthetic turf fields and the burning of coal, diesel, oil and gas, or other organic substances such as tobacco. PAHs have been known to be bioaccumulative, carcinogenic and disrupt the endocrine system. The new study, funded by the National Institute of Environmental Health Sciences (NIEHS), a branch of the National Institutes of Health, the U.S. Environmental Protection Agency and several private foundations, found that children exposed to high levels of PAHs in New York City had full scale and verbal IQ scores that were 4.31 and 4.67 points lower than those of less exposed children. High PAH levels were defined as above the […]

(Beyond Pesticides, July 2, 2009) The EPA has just finished up with a round of public hearings on a proposed plan to cap a part of the Palos Verdes Superfund Site. This 17 square mile area of ocean floor off the Southern coast of California is home to one of the largest deposits of DDT in the U.S. Despite the fact that this chemical has been banned in the U.S. for almost four decades, there is an approximate 110 tons of DDT in the sediment of the Palos Verdes Shelf. Concentrations of DDT and PCBs in fish continue to pose a threat to human health and the natural environment including the discovery of highly contaminated fish. In addition, a surge of additional problems with the lingering effects of DDT have risen in recent years, particularly with its buildup in our waterways. It has currently been identified as a threat to the Columbia River, as well as to the arctic. It has also been linked to a plethora of health concerns, including breast cancer, diabetes, non Hodgkin lymphoma, and autism. Most of the contamination of the Palos Verdes Shelf is attributed to The Montrose Chemical Corporation of California. At one time […]

(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 27, 2009) A recent, extensive study which investigated a variety of different chemicals, including organochlorine pesticides, in animal tissues reveals that marine mammals harbor high concentrations of hazardous chemicals in their brains. The results lay the groundwork for understanding how environmental contaminants influence the central nervous system of marine mammals. The study entitled “Organohalogen contaminants and metabolites in cerebrospinal fluid and cerebellum gray matter in short-beaked common dolphins and Atlantic white-sided dolphins from the western North Atlantic” is the first of its kind to find toxic chemicals in the brains of marine mammals. The study identified several contaminants including organochlorine pesticides like DDT, polychlorinated biphenyls (PCBs) and flame retardants in the cerebrospinal fluid and cerebellum gray matter of several species of marine mammals including the short-beaked common dolphins, Atlantic white-sided dolphins and the gray seal. PCBs were found in alarmingly high concentrations. Researchers found parts per million concentrations of PCBs in the cerebrospinal fluid of a gray seal. “We found parts per million concentrations of hydroxylated PCBs in the cerebrospinal fluid of a gray seal. That is so worrisome for me. You rarely find parts per million levels of anything in the brain,” remarked researcher, Eric Montie, […]

(Beyond Pesticides, May 8, 2009) The United Nations Environment Programme (UNEP) and the World Health Organization (WHO), in partnership with the Global Environment Facility, have announced a renewed international effort to combat malaria with an incremental reduction of reliance on the synthetic pesticide DDT. As recently as two years ago, WHO was criticized for promoting DDT as the answer for malaria control in Africa, leading activists to call for increased use of alternatives. DDT has been recognized as a significant human and environmental health risk, including increased risk of breast cancer a wealth of other health concerns, and have built up in waterways and, in particular, the arctic. Now, ten projects, all part of the global program “Demonstrating and Scaling-up of sustainable Alternatives to DDT in Vector Management,” involving some 40 countries in Africa, the Eastern Mediterranean and Central Asia, are set to test non-chemical methods ranging from eliminating potential mosquito breeding sites and securing homes with mesh screens to deploying mosquito-repellent trees and fish that eat mosquito larvae. The new projects follow a successful demonstration of alternatives to DDT in Mexico and Central America. There, pesticide-free techniques and management regimes have helped cut cases of malaria by over 60 […]

(Beyond Pesticides, January 16, 2009) The first comprehensive look at toxic contamination throughout the Columbia River Basin has been released by the U.S. Environmental Protection Agency. Issued today, the Columbia River Basin State of the River Report for Toxics compiles currently available data about four widespread contaminants in the Basin and identifies the risks they pose to people, fish, and wildlife. The four contaminants are: * Mercury * Dichlorodiphenyltrichloroethane (DDT) and its breakdown products * Polychlorinated biphenyls (PCBs) * Polybrominated diphenyl ether (PBDE) flame retardants. According to Elin Miller, EPA Regional Administrator in Seattle, a team of more than 20 federal and state agencies, Tribes, local governments and organizations teamed-up to draw this latest portrait of the toxic threats faced by the Columbia River Basin, which drains nearly 260,000 square miles across seven U.S. states and a Canadian province. “This is troubling news,” said EPA’s Miller. “Today’s Report shows that toxics are found throughout the Basin at levels that could harm people, fish, and wildlife. Federal, tribal, state, and local efforts have reduced levels of some toxics such as PCBs and DDTs, but in many areas, they continue to pose an unacceptable risk. Tackling this problem will require a coordinated […]

(Beyond Pesticides, June 12, 2008) A new study reports that pesticides, including DDT and tributyltin (TBT), have been found in deep-sea squids and octopods. This study is the first to analyze the chemical contamination of these deep sea organisms, and adds to the body of literature that demonstrates the far-reaching effects of pesticide use on global ecosystems. Pesticide contamination has been documented as far away from the point of use as the arctic and now the deep sea. In the study, to be published in the journal Marine Pollution Bulletin, Michael Vecchione of the National Oceanic and Atmospheric Administration (NOAA), and colleagues from the Virginia Institute of Marine Science of The College of William and Mary report finding a wide variety of chemical contaminants in nine species of cephalopods, a class of organisms that includes cuttlefishes and nautiluses along with squids and octopods. Cephalopods are important to the diet of cetaceans, which are marine mammals such as whales, dolphins and porpoises. Persistent organic pollutants (POPs) in the blubber of whales and some deep sea fish has already been documented. The twenty-two specimens analyzed were taken from depths between 1000 and 2000 meters (approximately 3,300 and 6,600 ft.) in the North […]

(Beyond Pesticides, May 29, 2008) A study published in the May issue of Environmental Health Perspectives shows a link between prenatal exposure to the pesticide DDT and poor attention-related skills in early infancy. This study follows in a long line of recent studies associated with the negative health effects of DDT including: diabetes; non-Hodgkin lymphoma; breast cancer; and autism. Despite the fact that DDT was banned in the U.S. in 1972, concentrations of this toxic chemical’s major metabolite, DDE, have remained alarmingly high in many ecosystems, including the waters of Los Angeles County, the arctic, and even U.S. national parks. All studies documenting the health effects of DDT and chemicals in the same family, organochlorines, are particularly important not just for understanding the lingering effects of DDT from days past, but because many countries continue to employ DDT as a method in controlling mosquitoes that transmit malaria, despite its toxicity, weakening efficacy, and availability of safer alternatives. Other organochlorines are still registered for use in the U.S.The study looked at 788 mother-infant pairs who met several criteria, which included living in a town adjacent to a Superfund site in New Bedford, Massachusetts, a location with known organochlorine contamination. Cord blood […]

(Beyond Pesticides, May 19, 2008) A 20-year study by the National Oceanic and Atmospheric Administration (NOAA) shows that environmental laws enacted in the 1970s are having a positive effect on reducing overall contaminant levels in coastal waters of the U.S. However, the report points to continuing concerns with elevated levels of metals and organic contaminants found near urban and industrial areas of the coasts. The report, “NOAA National Status and Trends Mussel Watch Program: An Assessment of Two Decades of Contaminant Monitoring in the Nation’s Coastal Zone from 1986-2005,” findings are the result of monitoring efforts that analyze 140 different chemicals in U.S. coastal and estuarine areas, including the Great Lakes.“It’s interesting to note that pesticides, such as DDT, and industrial chemicals, such as PCBs, show significant decreasing trends around the nation, but similar trends were not found for trace metals,” said Gunnar Lauenstein, manager of the NOAA Mussel Watch program. “What is of concern is that there are contaminants that continue to be problematic, including oil-related compounds from motor vehicles and shipping activities.” Significant findings from this report include the following: Decreasing trends nationally of the pesticide DDT are documented with a majority of the sites monitored along the […]

(Beyond Pesticides, May 8, 2008) New research shows that melting Antarctic glaciers are releasing once frozen stores of persistent organic chemicals, now banned in many parts of the world. Marine biologist, Heidi Geisz, a Ph.D. student at the Virginia Institute of Marine Science studying the fate and effect of organic contaminants in the Antarctic, has found that DDT concentrations in penguins has remained at the same levels as they were 30 years ago, when DDT was widely used. Arctic animals such as whales, seals and birds have had a significant decline in their DDT levels during the past decades, while the more stationary Antarctic penguins have not. The study, “Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem,” published in Environmental Science and Technology (DOI: 10.1021/es702919n), identifies the melting snow and ice as the continued source of total DDT in this southern ecosystem. The release of DDT also means that other persistent organic pollutants (POPs), including PCBs and PBDEs — industrial chemicals that have been linked to health problems in humans, are also being released. “DDT is not the only chemical that these birds are ingesting and it is certainly not the worst,” Ms. Geisz says. Ms. […]

(Beyond Pesticides, February 29, 2008) The National Park Service (NPS) recently released a report documenting airborne pesticides.  The report of the  Western Airborne Contaminants Assessment Project (WACAP), with data collected from 2002 to 2007, found high concentrations of “numerous” airborne contaminants, including current and former use pesticides. Contamination is widespread throughout twenty parks throughout the western United States and Alaska, exceeding consumption levels for humans and wildlife in some areas. According to the report, the contaminants of second and third “highest concern” are “Dieldrin – an acutely toxic insecticide banned from use in the U.S. since 1987 that decreases the effectiveness of the immune system” and “DDT – an insecticide banned in the U.S. since 1972 that reduces reproductive success.” NPS also reported that Dieldrin and DDT levels exceeded the threshold for recreational fishermen in several parks, and Dieldrin levels exceeded that for subsistence fishermen in all but Olympic National Park. Fish-eating birds are also at risk in some parks. While NPS could not establish a correlation between contaminant levels and fish reproductive effects due to small sample size, two parks produced individual “intersex” fish. However, NPS stated, “This condition is commonly associated with exposure to certain contaminants (e.g., dieldrin […]