An occasional series the environment: Pesticides linked to prostate cancer
What does a professional landscaper with 40 years on the job and Gleason 3+4=7 think?
(Note: I have been exchanging emails with Peter F. for years. He prefers to remain anonymous. for this story, He is quiet about his cancer.“My brothers know. The problem -- unfortunately, the problem is my mother. My mother couldn't handle it. And it would be a phone call every day. ‘How are you doing? When did you go to the doctor? When are you going back?’ And it's just not worth it.” He has been on Active Surveillance for almost eight years, recently upgraded. to a favorable intermediate-risk Gleason 3+4=7.)
By Howard Wolinsky
On Nov. 4, Peter F., 60, a retired landscaper from outside Boston, was driving his truck and listening to the news on the radio. A report got his rapt attention.
A newsreader said that Stanford University researchers had just published in the journal Cancer from the American Cancer Society a large study linking high exposures to 22 pesticides with the incidence of prostate cancer and prostate cancer deaths.
(Note: Exposure to pesticides likely is low for the vast majority of us. The focus in the study is on industrial agriculture. See below.)
Peter, a patient with intermediate-risk prostate cancer, often was exposed to three pesticides mentioned in the study,: 2,4-D (active ingredient in such products as Weed B Gone), trifluralin (the active ingredient in the consumer product, Preen) , and glyphosate (the active ingredient in Roundup).
Peter, who started his own lawn business at age 15, said he was never comfortable with his exposure to pesticides on the job.
“The one that bothers me is 2,4-D, which is a broad leaf weed control. And at one time, what [commercial applicators] would do is just spray it all over the lawn whether there were weeds or not, figuring, ‘Okay, we spray everything. If there's a weed, we got it.’”
He stopped using 2,4-D on his own lawn 10 years ago after two of hisdogs died from cancer. “My wife looked it up and found the connection to 2,4-D and cancer in dogs,” he said.
Dogs are considered to be particularly sensitive to 2,4-D.
Peter is well aware that there is no way to actually prove his cancer was caused by pesticide exposure. He wants to increase awareness of the issue,
The U.S. Environmental Protection Agency has considered trifluralin generally safe for workers and homeowners, The safety of Roundup has been a matter of debate, with thousands of lawsuits claiming it caused cancer in humans and conradictory positions on safety by U.S. and international agencies.
2, 4-D is the most widely used herbicide in the world, and the third most commonly used in North America.
The National Pesticide Information Center was cautious about linking 2,4-D and cancer: “Scientists have not found a clear link between 2,4-D and cancer in people.”
Homeowners have easy access to these pesticides. I found them all together on the shelves of my neighborhood Home Depot.
(Photo: Howard Wolinsky.)
Peter said he was least concerned about having applied pesticide treatments to lawns during his last 15 years of his 40 years doing residential lawn care. But he was concerned about all the time he spent standing on grass that had just been treated with pesticides by commercial applicators.
Peter, who was diagnosed initially with Gleason 6 low-risk prostate cancer almost eight years ago, was exposed often to trifluralin,
Researchers said there is no way to determine what role pesticide exposure in individual cases of prostate cancer.
Peter added: “I'm not panicking at all about any of this, because in my mind I know there are treatments. I've never really had a panic or a freakout about the diagnosis or what's going to happen.”
Interview with Simon John Christoph Soerensen, MD, lead author of the pesticide study
By Howard Wolinsky
Twenty-two pesticides showed consistent, direct associations with prostate cancer incidence, Stanford University researchers reported in a study appearing in the journal Cancer published by the American Cancer Society.
Researchers also found four pesticides were linked with the mortality risk: trifluralin (see above), cloransulam-methyl, diflufenzopyr, and thiamethoxam.
“The results of this study suggest a potential link between certain pesticides and increased prostate cancer incidence and mortality. These findings warrant further investigation of these specific pesticides to confirm their role in prostate cancer risk and to develop potential public health interventions,” the researchers said.
Following is a Q&A with with lead author of the pesticide study, Simon John Christoph Soerensen, MD, and PhD candidate in epidemiology, at Stanford University.
Why did you take an interest in pesticides?
Our interest in pesticides arose from the potential influence of environmental exposures on prostate cancer, especially given the high rates of the disease and its uneven distribution across different regions. The hypothesis was that pesticides, widely used in agricultural and landscaping contexts, could play a role in prostate cancer risk. By investigating this, we aimed to identify whether these chemicals might be environmental factors that, in addition to genetic and lifestyle factors, could contribute to prostate cancer. This foundational study serves as a stepping stone for more focused research on environmental exposures and their potential impact on prostate cancer.
We sought to investigate 295 pesticides, many of which have never been studied before and even less so when it comes to prostate cancer with the goal to create some hypotheses and motivate researchers to conduct further studies within this domain focusing on some of the pesticides we discovered as potentially carcinogenic. As you know, there is so much we still don't know about prostate cancer. Many other cancers have strong modifiable risk factors, e.g., lung and bladder cancer and their relationships with smoking.
As a risk for prostate cancer (PCa), how do pesticides compare to genetics, diet, and metabolic disease?
Prostate cancer is a complex process influenced by multiple factors, including genetics and potentially environmental exposures. While our understanding of the genetic factors related to prostate cancer is advancing our knowledge of how environmental exposures like pesticides contribute to prostate cancer risk remains less developed.
Does this impact homeowners?Or is this mainly a risk for agricultural workers and landscapers?
The study focused on large-scale environmental exposures rather than specific user demographics. More studies are needed to determine specific populations at risk.
Where do you go next with this?
This preliminary study opens several pathways for further research. Future work could involve more detailed studies that investigate the specific biological mechanisms by which certain pesticides may contribute to prostate cancer risk. Longitudinal studies would also help clarify individual exposures over time and enable a more precise assessment of pesticide-related risk.
Q&A with Alexander Putnam Cole, MD, expert on environmental health at Harvard
By Howard Wolinsky
I asked Alexander Putnam Cole, MD, an authority on prostate cancer and the environment to weigh in on the new pesticide study. I \interviewed him previously for Medscape for an article entitled “Urology's Inconvenient Truth: Warnings on the Impact of Climate Change at EAU.”
Is this a new idea of pesticides potentially being linked to PCa?
The idea of pesticides being linked to cancers is not new at all. If you look back at the history for example you will see that arsenic pesticides were classified as a "group 1" carcinogen (established casual relationship) back in the 1970s and with some small exceptions hasn't been used for decades in agriculture. Many other pesticides have been classified as "probably" or "possibly" carcinogenic by the International Agency for Research on Cancer (The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organization of the United Nations.). An example of that is glyphosate which is classified as "probably carcinogenic" by the IARC.
In terms of prostate cancer, the data is more limited and there are some big challenges in studying this. One example is that many workers exposed to these chemicals will use a large variety of chemicals and may have other exposures so figuring out exactly what is causing the cancer is challenging, then you have a disease like prostate cancer that has a pretty high prevalence for men in their 50s, 60s and 70s -- and probably most men in those age ranges have at some point been exposed to pesticides or herbicides. You can use inferential studies like this one but establishing causality is much harder.
(Alexander Putnam Cole, MD.)
I received a note from a landscaper who used a few of these chemicals and now has prostate cancer. Are the alternative safe chemicals that workers like him can use?
There are a number of different classification systems out there such as the IARC and EPA. And obviously it is confusing because there are some substances that are classified differently by these organizations like glyphosate. And then can look at this paper and see some of the pesticides in the paper have a much weaker association with prostate cancer. So it is clear that there is a range of effects, and many of these are substances here that probably aren't carcinogenic in the way that something like, say, arsenic, asbestos, or cigarette smoking may be. As far as being able to say yes this "definitely doesn't cause prostate cancer" much harder to prove in a study like this.
A good starting point is staying away from the Group 1 and Group 2 carcinogenics like glyphosate and the insecticides malathion and diazinon which have been classified probably carcinogenic to humans (Group 2A) tetrachlorvinphos and parathion have been classfied as possibly carcinogenic to humans (Group 2B).
So a couple of things here. First of all, it’s worth keeping in mind that a lot of the large-scale use of pesticides and herbicides involves industrial agriculture. Flooding can result in transfer of pesticides to drinking water and so forth.
And then you also have the issue that we still need a food supply and completely banning herbicides and pesticides would not work.
For homeowners, I think you want to stay away from the IARC classified substances listed above and then exercise precautions with any pesticides you are using. Also keep this in context there are some substances with much clearer links to prostate cancer: steroids, red meat consumption.
Of all the potential causes of PCa, where do pesticides stand--vs. aging, genes, metabolic disease, diet, and what else? Where would pesticides rank?
I think that genetics, metabolic conditions and diet probably have a larger effect when it comes to prostate cancer. But we should also keep in mind that many of these types of environmental risk factors work on multiple pathways--for example look at something like red meat consumption which a clear link to prostate cancer (IARC Group 1 carcinogen). In addition to the direct effects of red meat on prostate cancer you can see all these other pathways where industrial farming may be linked to prostate cancer such as loss of greenspace (associated with higher rates of prostate cancer), wildfires and air pollution are associated with higher risks of cardiopulmonary mortality associated with higher exposure to particular pollution.
In Brazil, where rainforest is being burned to produce farmland you see wildfire-associated fine particulate matter (PM2.5) concentrations have been shown to have a significant association with prostate cancer mortality. So pesticides are part of the same process as a lot of this and probably has a small part of play but you have to keep in mind the larger picture.
Why wait? Get your pass to the Jan. 4 webinar “AS 25”
By Howard Wolinsky
What’s happened in prostate cancer and Active Surveillance in 2024? What’s on tap for 2025?
You can sign up now to find out in the program “AS 25,” scheduled for noon-1:30 p.m. Eastern on Saturday, January 4, 2025.
Subscribe here:
Current subscribers and founding members will receive a free registration link via a separate publication.
This will be the first webinar sponsored by TheActiveSurveillor.com. If you can’t afford a subscription or face other issues, such as an international bank boycott, contact me and I’ll get you a free pass. I will report anything newsworth in the newsletter.
(Counterclockwise starting in upper left top row: Dr. Jonathan Epstein, Dr. Brian Helfand, Dr. Timothy Showalter, and Dr. Christian Pavlovich.)\
Panelists:
—Jonathan Epstein, MD, the famed uropathologist, who will soon relaunch his practice in New York City. This will be Epstein’s first appearance before a patient group since April 2023.
—Brian Helfand, MD, PhD, chief of urology at Endeavor Health outside Chicago, an expert not only in prostate cancer but also in molecular biology.
—Timothy Showalter, MD, MPH, medical director of ArteraAI, which has made news with its prostate test to help patients decide whether to go on AS.
—Christian Pavlovich, MD, who runs the Active Surveillance program at Johns Hopkins and recently co-authored a major study on diet.
ASPI presents: How you can help advance research on Active Surveillance
By Howard Wolinsky
Without clinical trials, such as ProtecT, patients with lower-risk prostate cancer would have had no choice other than aggressive treatment with risks of side effects impacting their quality of life. I have participated in about a dozen trials as a patient and a patient researcher.
I highly recommend participation in trials. I have been in studies on diet and low-risk prostate cancer, genetics and medications and low-dose aspirin and preventing heart attacks.
Look for trials on Active Surveillance that you potentially can join at ClinicalTrials.gov
Active Surveillance Patients International (ASPI) is holding a webinar at 12:00PM ET Saturday, November 30, entitled “How you can help in clinical research on Active Surveillance.”
REGISTER HERE: https://zoom.us/meeting/register/tJIocOCupz4jGtX8fHJ036bYGHYIjLfwfRzk
Speakers will include Kevin Shee, MD, PhD, a researcher at the University of California, San Francisco, and Mike Scott, founder of Prostate Cancer International and an early advocate for Active Surveillance.
Dr. Shee has been involved in multiple studies, the most recently one on whether men 75 and above should stop active surveillance.
Though not a prostate cancer patient himself, Mike Scott was the founder of one of the first support groups for men on AS. ASPI this year presented him with its 2024 Thráinn Thorvaldsson Award for Patient Advocacy.
A question-and-answer session will follow the presentations.
If you have questions, please send them to: contactus@aspatients.org