US county-level data point to specific pesticides that may increase prostate cancer incidence and death.
Photo by Arjun Mj on Unsplash
Researchers have identified 22 pesticides consistently associated with the incidence of prostate cancer in the United States, with four of the pesticides also linked with prostate cancer mortality. The findings are published by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society.
To assess county-level associations of 295 pesticides with prostate cancer across counties in the United States, investigators conducted an environment-wide association study, using a lag period between exposure and prostate cancer incidence of 10–18 years to account for the slow-growing nature of most prostate cancers. The years 1997–2001 were assessed for pesticide use and 2011–2015 for prostate cancer outcomes. Similarly, 2002–2006 were analysed for pesticide use and 2016–2020 for outcomes.
Among the 22 pesticides showing consistent direct associations with prostate cancer incidence across both time-based analyses were three that had previously been linked to prostate cancer, including 2,4-D, one of the most frequently used pesticides in the United States. The 19 candidate pesticides not previously linked to prostate cancer included 10 herbicides, several fungicides and insecticides, and a soil fumigant.
Four pesticides that were linked to prostate cancer incidence were also associated with prostate cancer mortality: three herbicides (trifluralin, cloransulam-methyl, and diflufenzopyr) and one insecticide (thiamethoxam). Only trifluralin is classed by the Environmental Protection Agency as a “possible human carcinogen,” whereas the other three are considered “not likely to be carcinogenic” or have evidence of “non-carcinogenicity.”
“This research demonstrates the importance of studying environmental exposures, such as pesticide use, to potentially explain some of the geographic variation we observe in prostate cancer incidence and deaths across the United States,” said lead author Simon John Christoph Soerensen, MD, of Stanford University School of Medicine. “By building on these findings, we can advance our efforts to pinpoint risk factors for prostate cancer and work towards reducing the number of men affected by this disease.”
Living less than 500m from pesticide use prior to conception and during early pregnancy could increase the risk of stillbirths, according to new research published in the American Journal of Epidemiology.
Researchers from the University of Arizona found that during a 90-day pre-conception window and the first trimester of pregnancy, select pesticides, including organophosphates as a class, were associated with stillbirth.
“In this study, some specific ingredients stood out due to their significant associations with stillbirth risk,” said first authorMelissa Furlong, PhD, who studies the chronic health effects of environmental contaminants as an assistant professor and environmental epidemiologist at the Zuckerman College of Public Health. “These findings underscore the importance of considering individual pesticides rather than just the overall pesticide class, as specific chemical compounds may pose unique risks. It also highlights the potential for pre-pregnancy exposures to affect reproductive outcomes.”
To conduct the study, researchers linked Arizona pesticide use records for 27 different pesticides with state birth certificate data that included 1 237 750 births and 2290 stillbirths from 2006 to 2020.
They found that living within 500m of specific pyrethroid, organophosphate or carbamate pesticide applications during a 90-day pre-conception window or the first trimester was associated with an increased risk of stillbirth.
Specifically, the pesticides cyfluthrin, zeta-cypermethrin, organophosphates as a class, malathion, carbaryl and propamocarb hydrochloride were linked to increased stillborn births pre-conception. During the first trimester, fenpropathrin, permethrin, organophosphates as a class, acephate and formetanate hydrochloride were associated with stillbirths.
“Among organophosphates, acephate showed the strongest effect estimates on stillbirth, so that exposure to acephate in the first trimester was associated with a doubling of risk,” said co-author Paloma Beamer, PhD, a professor and interim associate dean at the Zuckerman College of Public Health. “Within the pyrethroid class, cyfluthrin exposure during the 90 days prior to conception almost doubled the risk of stillbirth.”
Pesticides are chemical substances used to control pests in various settings. They are commonly categorized into different classes, such as organophosphates, pyrethroids and carbamates. The primary route of exposure for most people is through diet, but household use, agricultural drift and occupational exposure are also significant pathways.
Researchers say while some pesticides may not have been directly implicated in this study, they could still pose risks to maternal and foetal health.
Pregnant women may be particularly vulnerable to the adverse effects of pesticide exposure due to physiological changes during pregnancy, such as increased metabolic rate, altered hormone levels and changes in the immune system. The developing foetus may be more susceptible to the toxic effects of pesticides during this period of rapid growth and development.
“Further research is essential to fully understand the safety profiles of various pesticides and to understand the underlying mechanisms of pesticide-induced stillbirth,” Furlong said. “This study underscores the need to develop strategies for mitigating exposure to protect maternal and foetal health.”
A report from the world’s leading scientific and medical experts on hormone-related health conditions raises new concerns about the profound threats to human health from endocrine disrupting chemicals (EDCs) that are ubiquitous in our surroundings and everyday lives.
The report, “Endocrine Disrupting Chemicals: Threats to Human Health” provides a comprehensive update on the state of the science around EDCs, with increasing evidence that this large group of toxic substances may be implicated in rising global health concerns.
The report from the Endocrine Society, co-produced with the International Pollutants Elimination Network (IPEN), includes detailed analyses on exposure to EDCs from four sources: plastics, pesticides, consumer products (including children’s products), and per-and polyfluoroalkyl substances (PFAS), a class of thousands of chemicals known or suspected to be EDCs.
The Endocrine Society-IPEN report is being released during the U.N. Environment Assembly (UNEA-6) meeting in Nairobi.
At UNEA key agenda items include welcoming the newly adopted Global Framework on Chemicals, advancing global action on highly hazardous pesticides, and threats to the circular economy from plastics and toxic chemicals.
The groups’ report anticipates an update from UNEP and the WHO expected later this year on their 2012 Report on State of the Science of Endocrine Disrupting Chemicals.
“A well-established body of scientific research indicates that endocrine-disrupting chemicals that are part of our daily lives are making us more susceptible to reproductive disorders, cancer, diabetes, obesity, heart disease, and other serious health conditions,” said the report’s lead author, Andrea C. Gore, PhD, of the University of Texas at Austin, and a member of the Endocrine Society’s Board of Directors.
“These chemicals pose particularly serious risks to pregnant women and children. Now is the time for the UN Environment Assembly and other global policymakers to take action to address this threat to public health.”
By interfering with hormones and their actions, EDC exposure can impact many health-related functions, with consequences for increased risks of many serious conditions.
Evidence suggests that EDCs in the environment contribute to disorders such as diabetes, neurological disorders, reproductive disorders, inflammation, and compromised immune functioning.
Two of the four analyses in the report look at EDCs used in plastics and as pesticides.
Global production of plastics and pesticides is increasing even as scientists warn that chemical and plastic pollution is an escalating crisis. Glyphosate is the world’s most widely used herbicide, and a recent study found that glyphosate has eight of ten key characteristics of an EDC. Other studies have found links between glyphosate and adverse reproductive health outcomes.
Plastics are made with thousands of known toxic substances, some of which are known or suspected EDCs. The report examines bisphenols and phthalates, two toxic chemical groups found in many plastics. Exposures to EDCs from plastics occur at all phases of plastics production, use, disposal, and even from recycled plastics.
The Endocrine Society-IPEN report notes that, while evidence of health threats from EDCs is mounting, current regulations have not kept pace.
“EDCs are different than other toxic chemicals, but most regulations fail to address these differences,” said IPEN Science Advisor Sara Brosché, PhD. “For example, we know that even very low doses of endocrine disrupting chemicals can cause health problems and there may be no safe dose for exposure to EDCs. However, regulations typically do not protect against low-dose effects. We need a global approach to controlling EDCs based on the latest science with a goal of protecting the human right to a healthy environment.”
At the UNEA-6 meeting, IPEN is also releasing a new report on “The Global Threat from Highly Hazardous Pesticides,” highlighting ongoing health and environmental risks from HHPs, especially in low- and middle-income countries.
DDT, glyphosate, and chorpyrifos, three HHPs reviewed in the Endocrine Society report, are also highlighted in the new IPEN report as they continue to pose health threats especially in the Global South.
In addition to plastics and pesticides, the report looks at EDC exposures from arsenic and lead, and from widely used per- and polyfluoroalkyl substances (PFAS), humanmade “forever chemicals” used as oil and water repellents and coatings. Lead remains in use in paint in many countries, as documented in recent IPEN reports. Endocrine-related conditions from lead exposure may include delayed onset of puberty and early menopause. Arsenic is a common metal that has long been linked to cancer and other health conditions, and more recent evidence shows that arsenic can disrupt multiple endocrine systems. PFAS are used in hundreds of products including clothing and food packaging, but recent studies show that some PFAS can disrupt hormones such as oestrogen and testosterone and impair thyroid hormone functions.
In a study that signals potential reproductive and health complications in humans, now and for future generations, researchers from McGill University, the University of Pretoria, Université Laval, Aarhus University, and the University of Copenhagen, have concluded that fathers exposed to environmental toxins, notably DDT, may produce sperm with health consequences for their children.
The decade-long research project examined the impact of DDT on the sperm epigenome of South African Vhavenda and Greenlandic Inuit men, some of whom live in Canada’s North.
The study, published in the journal Environmental Health Perspectives, demonstrates a link between long-term exposure to DDT and changes in the sperm epigenome. These changes, particularly in genes vital for fertility, embryo development, neurodevelopment, and hormone regulation, correspond to increased rates of birth defects and diseases, including neurodevelopmental and metabolic disorders.
“We identified regions of the sperm epigenome that are associated with the serum levels of DDE (chemicals that form when DDT breaks down) and this association follows a dose-response trend. I think that’s quite striking, in that the more DDE you’re exposed to, the higher the chromatin, or DNA methylation defects are in the sperm,” said Ariane Lismer, PhD, the study’s lead author, who completed the work while pursuing her PhD at McGill’s Department of Pharmacology and Therapeutics.
“We demonstrate the sperm epigenome’s response to toxin exposures may be linked with disease in the next generation,” said Sarah Kimmins, PhD, who led the research as Professor of Pharmacology and Therapeutics at McGill and is also now a professor in the Department of Pathology and Cell Biology at Université de Montréal. “This is a critical new step for the field because while there are many studies of animals demonstrating toxin effects on the sperm epigenome, studies in humans have not comprehensively demonstrated this.”
Malaria, climate change, and the ‘grasshopper effect’
Despite a global ban on DDT to protect humans and the environment from its effects, the South African government has special permission to use it as an insecticide to control malaria. In some areas, home interiors are coated with the toxin. The study’s findings underscore the urgency to find alternative ways to control malaria and other vector-borne diseases.
“The reality is that people, especially young children and pregnant women, are still dying from malaria. We cannot afford for people in malaria-endemic regions to refuse spraying of their houses, as it will increase their risk of getting malaria,” says Tiaan de Jager, PhD, Dean of the Faculty of Health Sciences and Professor in Environmental Health at the School of Health Systems and Public Health at the University of Pretoria.
What’s more, the number of people and animals exposed to DDT is reportedly increasing due to climate change. DDT can travel vast distances through what is known as the ‘grasshopper effect,’ evaporating with warm air and returning to Earth with rain and snow in colder regions, where it persists in the Arctic food chain.
Rethinking fathers’ role in child development
The findings also highlight the importance of considering fathers in discussions about child health and development. While it’s commonly understood that women should avoid exposure to environmental contaminants during pregnancy, less attention has been given to how toxins affect fathers.
“We tend to think all fathers have to do is fertilise. But in fact, we forget that half of that genome and epigenome comes from the fathers, and half of it comes from the mothers. What that epigenome does in embryo development is critical for normal development,” says study co-author, Janice Bailey, PhD, formerly Professor of Animal Sciences at Université Laval and now the Scientific Director at Fonds de Recherche du Québec en Nature et Technologies (FRQNT).
Although the study focuses on DDT exposures, the researchers say it is not a leap to suggest that exposures to more common household endocrine disruptors such as those found in cosmetics and personal care items may act similarly.
A recent report by the US Centers for Disease Control and Prevention found more than 80% of urine samples from children and adults in the US contained the herbicide glyphosate. A study published in Scientific Reports takes this research one step further and is the first to link the use of the herbicide Roundup®, a widely used weed killer, to convulsions in animals.
Glyphosate, the weed killer component in Roundup®, is the world’s most commonly used herbicide by volume and by land-area treated. Glyphosate-resistant crops account for almost 80% of transgenic crop cultivated land, which has resulted in an estimated 6.1 billion kg of glyphosate sprayed across the world from 2005 to 2014. Roundup® is used at both industrial and consumer levels, and its use is projected to dramatically increase over the coming years. A major question, yet to be fully understood, is the potential impact of glyphosate on the nervous system.
“It is concerning how little we understand the impact of glyphosate on the nervous system,” said project leader Akshay S. Naraine, a PhD student at FAU and the International Max Planck Research School for Synapses and Circuits. “More evidence is mounting for how prevalent exposure to glyphosate is, so this work hopefully pushes other researchers to expand on these findings and solidify where our concerns should be.”
Resultsshowed that glyphosate and Roundup® increased seizure-like behaviour in soil-dwelling roundworms and provides significant evidence that glyphosate targets GABA-A receptors. These communication points are essential for locomotion and are heavily involved in regulating sleep and mood in humans. What truly sets this research apart is that it was done at significantly lower levels than recommended by the EPA and those used in past studies.
“The concentration listed for best results on the Roundup® Super Concentrate label is 0.98% glyphosate, which is about 5 tablespoons of Roundup® in 1 gallon [3.8 litres] of water,” said Naraine. “A significant finding from our study reveals that just 0.002% glyphosate, a difference of about 300 times less herbicide than the lowest concentration recommended for consumer use, had concerning effects on the nervous system.”
Using C. elegans, a soil-dwelling roundworm, researchers first tested glyphosate alone and then both the US and UK formulations of Roundup® from two distinct time periods – before and after the UK’s 2016 ban on polyethoxylated tallowamine (POEAs). These conditions were selected to pinpoint which effects are specific to the active ingredient glyphosate, Roundup® formulations in general, the POEAs surfactants, or any combination of these.
The study found that the active ingredient glyphosate exacerbated convulsions in C. elegans and suggest the GABA-A receptor as a neurological target for the observed physiological changes. The data also indicate that there is an important distinction between exposure to glyphosate and Roundup®, with Roundup® exposure increasing the percentage of C. elegans that did not recover from seizure activity. The non-recovery phenotype and prolonged convulsions in C. elegans from this study have helped to set a foundation for understanding nuanced physiological effects of herbicide that occur at concentrations exponentially below neurotoxic levels.
“Given how widespread the use of these products is, we must learn as much as we can about the potential negative impacts that may exist,” said lab head Ken Dawson-Scully, PhD, professor at Nova Southeastern University. “There have been studies done in the past that showed the potential dangers, and our study takes that one step further with some pretty dramatic results.”
Findings also generate concern over how herbicide use might affect soil-dwelling organisms like C. elegans.
“These roundworms undergo convulsions under thermal stress, and our data strongly implicates glyphosate and Roundup® exposure in exacerbating convulsive effects. This could prove vital as we experience the effects of climate change,” said Naraine.
This study provides evidence to further investigate how chronic exposure and accumulation may lead to neurodegenerative diseases such as Parkinson’s disease. Importantly, there also is a sub-neurodegenerative threshold that may dramatically impact dysregulation of neurotransmission.
“As of now, there is no information for how exposure to glyphosate and Roundup® may affect humans diagnosed with epilepsy or other seizure disorders,” said Dawson-Scully. “Our study indicates that there is significant disruption in locomotion and should prompt further vertebrate studies.”
A commonly-used pesticide could be contributing to the global obesity epidemic, according to a new study.
Researchers discovered that chlorpyrifos slows down the burning of calories in the brown adipose tissue of mice. Reducing this burning of calories, a process known as diet-induced thermogenesis, causes the body to store these extra calories, promoting obesity. Chlorpyrifos is banned for use on foods in Canada, and also now banned in the US and, as of last year, the EU, but widely sprayed on fruits and vegetables in many other parts of the world. In South Africa it is banned for residential use but is still used in agriculture.
Scientists made the discovery after studying 34 commonly used pesticides and herbicides in brown fat cells and testing the effects of chlorpyrifos in mice fed high calorie diets. Their findings were published in Nature Communications and could have important implications for public health.
“Brown fat is the metabolic furnace in our body, burning calories, unlike normal fat that is used to store them. This generates heat and prevents calories from being deposited on our bodies as normal white fat. We know brown fat is activated during cold and when we eat,” said senior author Gregory Steinberg, professor of medicine and co-director of the Centre for Metabolism, Obesity, and Diabetes Research at McMaster.
“Lifestyle changes around diet and exercise rarely lead to sustained weight loss. We think part of the problem may be this intrinsic dialling back of the metabolic furnace by chlorpyrifos.”
Steinberg said chlorpyrifos would only need to inhibit energy use in brown fat by 40 calories every day to trigger obesity in adults, which would translate to an extra 2kg of weight gain per year.
He said that while several environmental toxins including chlorpyrifos have been associated with increasing obesity rates in both humans and animals, these studies have mostly attributed weight gain to increases in food intake and not calorie burning.
“Although the findings have yet to be confirmed in humans, an important consideration, is that whenever possible consume fruits and vegetables from local Canadian sources and if consuming imported produce, make sure it is thoroughly washed,” said Steinberg.
