Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.
If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.
This week’s study is…
Residential proximity to pesticide application as a risk factor for childhood central nervous system tumors
We previously published about this research in a story titled “Could Prenatal Pesticide Exposure Cause Medulloblastoma?” which can be found here. The study was originally published in the research journal Environmental Research. You can view the abstract of the study here.
Heavy use of pesticides has become a critical component of modern industrialized agriculture. This form of agriculture prioritizes producing the maximum yield of produce possible, but these practices have come under increasing scrutiny in recent years. Industrial agriculture can leave soil devoid of nutrients and polluted. Meanwhile, pesticides have been found to cause harm to humans, can poison nearby ecosystems and waterways, and also kill billions of bees, which continue to play a critical role in our food production and survival.
The US in particular has been very lax about regulating pesticide use, even when certain pesticides have been linked to significant harm to people and the environment. Now a new study has emerged linking specific pesticides to certain types of brain and central nervous system tumors in children. These findings mirror previous studies that have identified pesticide exposure as a risk factor for certain cancers.
Looking at data from the California Cancer Registry, the researchers identified a total of 667 cancer cases in patients age six or younger. These were restricted to mothers living in rural regions and who gave birth between 1998 and 2011. They were compared alongside a control group of 123,158 births. Potentially carcinogenic pesticides were selected based on EPA classifications. Meanwhile, application of pesticides was assessed based on California’s Pesticide Use Reporting system (pesticides being used within 4000m of residence at birth).
The scientists were able to link specific pesticides as risk factors for specific CNS and brain tumors. Diffuse astrocytoma risk was increased with exposure to triforine, bromacil, thiophanate-methyl, and kresoxim-methyl. Medulloblastoma risk was increased with exposure to linuron, chlorothalonil, dimethoate, and propiconazole. Ependymoma risk was increased with exposure to thiophanate-methyl.
It should be noted that this increased risk was present in mothers that were merely living in close proximity to farms and fields where these pesticides were being used; they were not deploying or handling the pesticides directly.
Medulloblastoma is a brain cancer that is generally considered rare; however, it is the most common type of cancer to originate in the brain in kids. Symptoms include falling, stumbling gait and general loss of coordination, vomiting, headaches in the morning, optic disc swelling, and ataxia. Treatment may result in serious adverse effects. Five year survival rate is around 69 percent. To learn more about medulloblastoma, click here.
Astrocytomas are a type of brain tumor that originates in astrocytes, a certain type of glial cell. There are several different types of astrocytoma including glioblastoma, which is highly lethal and is the most widespread form of brain cancer in adults. Symptoms include nausea, headaches, loss of consciousness, stroke-like symptoms, and changes to personality. Treatment varies depending on the variant. To learn more about astrocytoma, click here.
An ependymoma is a form of tumor that occurs in a tissue of the central nervous system (CNS) called the ependyma. In children, it is often found in the skull but is more likely to appear in the spine in adults. Symptoms include changes to back flexibility, severe headache, constipation, vision loss, drowsiness, bilateral Babinski sign, gait changes, and vomiting. Treatment is most typically surgical removal followed by radiation therapy. Click here to learn more about ependymoma.
Why Does it Matter?
Brain tumors, though varying widely in type and severity, can be a frightening and difficult to treat and diagnose, particularly in children. The origins of many childhood cancers, as well as brain tumors, are not well understood, but the findings from this study draw a direct link to certain pesticides and certain forms of brain and CNS tumors:
“Many pesticides are neurotoxicants, and have even been found in cord blood, indicating placental transfer of these toxins to the developing fetus…this, in turn, suggests prenatal pesticide exposure may increase childhood brain cancer risk.” – Co-author Shiraya Thompson
Often one of the most effective ways to bring down cancer case numbers and reduce risk is to avoid known carcinogens, so understanding this direct link can inform both the public and policymakers about the risks that heavy pesticide use can pose to nearby populations:
“Exposure to certain pesticides, simply through residential proximity to agricultural applications during pregnancy, may increase the risk of childhood central nervous system tumors…policy interventions to reduce pesticide exposure in individuals residing near agricultural fields should be considered to protect the health of children.” – Dr. Beate Ritz, MD, PhD