In recent decades, rates of some cancers, such as colorectal cancer, have been rising in young adults under the age of 50. One possible explanation for this rise is a parallel rise in obesity rates and changes in diet, activity levels and lifestyle.
However, says Kimmie Ng, MD, MPH, director of Dana-Farber’s Young-Onset Colorectal Cancer Center, these factors do not explain the trend completely. She sees many young patients with colon cancer who are not obese and maintain healthy lifestyles. She and other experts in the field suspect environmental exposure might also be playing a role, particularly an exposure that has been on the rise during the past several decades.
Microplastics are an example of a rising presence in the environment that could be increasing the risk of cancer in young people. “Microplastics are of real concern given the rising burden of plastics in general in our lifestyles and in our environment,” says Ng.
What are microplastics?
Microplastics are tiny bits of plastic less than 5 millimeters in diameter. They can be invisibly small and are present in the air we breathe, the water we drink and the food we eat.
They come from a range of plastics in products from insecticides and pharmaceuticals to microbeads in cosmetic products, to synthetic clothing, tires, and industrial materials. Over the past 70 years, plastic production has skyrocketed and continues to rise.
How much are cancer rates rising in young people?
Rising rates of cancer among young people are extremely concerning. According to the American Cancer Society’s 2025 Cancer Facts and Figures report, people under the age of 50 were the only group to experience a rise in cancer rates between 1995 and 2021.
Young onset colorectal cancer, for instance, has risen 2-3% per year for the last several years. Other cancers with rising rates in young adults include breast cancer and lung cancer.
“The rate of rise of colorectal cancer is steepest among the youngest adult patients,” says Ng. “It’s steepest for those in their 20s, and higher for those in their 30s than in their 40s or 50s.”
What evidence exists that microplastics might be related to cancer?
Microplastics have the potential to enter the body through the lungs as we breathe, through the digestive tract as we eat and drink, and through the skin.
There are some studies in humans that have made links between microplastics and processes in the body that contribute to cancer. There are also studies in animals that more deeply explore the cause and effect between microplastics and the cells in our bodies.
Microplastics have so far been found in human and animal tissues including in lung, liver, placenta, and arteries. They have also been shown to have many negative effects related to cancer, including:
- Causing chronic inflammation
- Suppressing immune functions that fight cancer
- Affecting how fast cells grow and divide
- Affecting levels of hormones, including reproductive hormones
- Affecting plaques in the arteries
- Causing DNA damage
- Disrupting the balance between microbes and mucus lining in the gut, potentially exposing cells lining the gut to harm
- Carrying toxic pollutants with potential cancer risks
However, says Ng, “the field is very much in its infancy. There are relatively few studies out there. We need more studies of human tissues and studies of how microplastics influence diseases like cancer.”
What research is being done to understand more about microplastics?
At Dana-Farber, Ng is collaborating with experts in environmental science to begin to learn more about how microplastics affect the colon and the development of colorectal cancer. There are many challenges ahead as the field develops reliable, standardized ways to measure the presence of microplastics.
Research that aims to understand how microplastics affect health is critically important to inform future decisions about plastics at a regulatory level.
What can I do to reduce my risk of microplastics?
There are a few things to try, such as filtering water, reducing single-use plastics and plastic utensils, avoiding food packaged in plastic, opting for natural-fiber clothing, and vacuuming frequently.
Some of these tips may sound easy to implement, but in practice, reducing microplastic exposure is extremely difficult. For instance, access to non-plastic packaged foods and exposures to higher levels environmental pollution that includes microplastics may vary from one community to the next.
“I think it’s going to be really challenging to decrease the level and the amount of plastic in our world,” says Ng. “We really need more research so that systemic changes can be made.”
What else can I do to reduce my risk of cancer if I am a young adult?
A key first step is to follow all cancer screening guidelines. Early detection and early treatment are critical approaches to improve how well a person does with cancer treatment.
Cancer screening guidelines generally don’t include people under age 40 or 45 because most new cancer cases still occur in older adults. Keep an eye on screening guidelines, though. They have been changing to include people at younger ages as young onset cancer rates rise and as more is learned about cancer risks.
Another important practice is to pay attention to your body so you can recognize early warning signs. If you see changes, go see a doctor. Examples of changes to pay attention to include:
For colorectal cancer:
- Blood in the stool
- Abdominal pain, pelvic pressure, or a sense of bloating. These are particularly common in the types of colorectal cancers seen in younger people.
- Changes in bowel habits such as new diarrhea, constipation, or a decrease in the diameter of the stool, such as if they become pencil-thin.
- Unintentional weight loss.
- Fatigue or shortness of breath with exertion, which can indicate anemia.
Learn more about colorectal cancer screening.
For breast cancer:
- A lump in the breast found during a self-exam.
- Any changes to the size, shape, or texture and coloration of the breast.
- Abnormal discharge from the nipple.
Learn more about breast cancer screening.
For lung cancer:
- A cough that doesn’t get better.
- Shortness of breath that persists and is not explained by a recent illness.
- Back pain, particularly between the shoulder blades, that is not explained by injury or asthma.
- Coughing up blood.
- Unexplained weight loss.
About the Medical Reviewer
Dr. Thejus Jayakrishnan is a gastrointestinal medical oncologist at Dana-Farber Cancer Institute and Brigham and Women's Hospital, and an Instructor in Medicine at Harvard Medical School. He earned his medical degree from the All India Institute of Medical Sciences in New Delhi, India, followed by residency training in internal medicine at Allegheny Health Network, Pittsburgh. He completed his medical oncology fellowship at Cleveland Clinic, where he worked closely with Dr. Alok Khorana, a key mentor who helped shape his focus on gastrointestinal oncology.
Dr. Jayakrishnan’s research has uncovered unique metabolic pathway alterations in early-onset colorectal cancer, correlations between plasma metabolomic differences and tumor-associated microbiome in early-onset colorectal cancer, and distinct mutational landscapes in early-onset cholangiocarcinoma. His work has earned multiple ASCO Conquer Cancer Merit Awards and has been published in NPJ Precision Oncology, JCO Precision Oncology, and Nature Scientific Reports. His current research focuses on addressing critical gaps in the understanding of early-onset gastrointestinal cancers through translational research using multi-omic tools, with the goal of developing biomarkers for screening and therapeutic interventions.
In the clinic, Dr. Jayakrishnan treats patients with all types of gastrointestinal cancers and works closely with the Young-Onset Colorectal Cancer Center. He is dedicated to translating his research findings into clinical trials aimed at improving the care and treatment outcomes for individuals with gastrointestinal cancers globally.
Thanks for this great article! Microplastics are truly everywhere 🙁 but at least it’s good to be informed