Plastic Particles in Foods Linked to Cancer Risk, Say Studies

"You are what you eat," as the saying goes. Remember that the next time you reach for a convenience store packaged snack that's so full of preservatives, it'll still be edible if you find it under your driver's seat a year later. Think twice before microwaving your lunch in a plastic dish. Many of the most highly processed, mass-produced foods you eat contain hard-to-pronounce industrial formulations, and even microplastics that may leach into the food from the packaging. This exposure to the plastic particles found in your favorite frozen dinner or pre-packaged snacks could pose health risks.

Manufacturers and government regulatory agencies assure us that plastics that come in contact with food are safe for human health. But some experts believe that proof of safety and oversight are inadequate. There are scientists who believe regular consumption of these ultra-processed, pre-packaged meals containing "industrially derived ingredients" correlate with rising rates of certain cancers. That's the case in a recent observational study published in the Lancet's eClinicalMedicine, for example, in which researchers monitored the health and diets of about 200,000 middle-age people.

Over the course of the 10-year study, the participants recorded 24-hour food diaries on five separate occasions. Reviewing participants' health outcomes over the decade, the researchers from London's Imperial College School of Public Health found that higher consumption of ultra-processed foods was associated with a greater risk of developing cancer and increased risk of dying from cancer. For every 10% increase in ultra-processed food in a person's diet, the researchers found a 2% increased incidence cancer in general, and a 19% increase specifically for ovarian cancer.

Dr. Eszter Vamos, lead author of the study, acknowledged that the study does not prove causation, but suggested that limiting ultra-processed foods in our diet could lead to health benefits. "This study adds to the growing evidence that ultra-processed foods are likely to negatively impact our health, including our risk for cancer," she said in a statement.

The Best Eating Habit to Lower Your Cancer Risk, New Study Says

What could be lurking in your snacks?

Candy convenience store shelves — TY Lim/Shutterstock

What is it about industrial, mass-produced foods that may promote cancer?

"Ultra-processed foods may contain possible cancer-causing chemicals generated during food processing as well as chemicals from the packaging of these foods," says Lisa Young, PhD, RDN, registered dietitian nutritionist and member of our Medical Expert Board. "In addition, they can contribute to chronic inflammation, which could exacerbate cancer risk."

The researchers involved in the new Imperial College School of Public Health study say the inferior nutrition in processed foods, which are typically high in energy, saturated fats, salt, and sugars and low in vitamins and fiber, may explain the association between UPF and cancer.

"The UK study findings are consistent with what we know about the importance of eating a healthy diet to lower our cancer risk," says Young.

The Imperial College scientists also point to research showing that endocrine-disrupting chemicals, such as phthalates and bisphenols (think BPA), found in food packaging have been detected in people who consume high amounts of ultra-processed foods. A 2019 study estimated that an average American consumes 39,000 to 52,000 microplastic particles every year.

Do you take plastic?

Ingested plastics may have an effect, as well, the UK research suggests. In a separate study published in 2019, researchers claimed that the average person could be ingesting five grams—about the amount of plastic in a credit card—every week. The study by University of Newcastle in Australia analyzed 50 studies on the ingestion of microplastics by people and estimated that individuals take in 2,000 microscopic plastic particles from food, water, and air each week. Other research has identified these microplastics in the atmosphere, drinking water and human food products "thus potentially leading to adverse health effects upon ingestion and/or inhalation," write scientists reporting in the Journal of Hazardous Materials in 2019.

"You'd think Food & Drug Administration DA has the same ability and oversight over invisible ingredients that are intentionally added to foods or unintentionally get into foods through contact with food packaging or other surfaces," says Leo Trasande, MD, a pediatrician and author of Sicker, Fatter, Poorer: The Urgent Threat of Hormone-Disrupting Chemicals to Our Health and Future. "Unfortunately that's not the case. The FDA have the same kind of oversight."

Before you grab a trash bag, and make a beeline for your pantry and fridge, keep in mind that the Imperial College study was observational, meaning it cannot prove that ultra-processed foods cause cancer.

"The relationship between ultra-processed food and health risks is quite complicated to study, and it's important not to put too much stock in this [particular study]," says registered dietitian nutritionist Elizabeth Ward, MS, RDN, and co-author of The Menopause Diet Plan, A Natural Guide to Managing Hormones, Health, and Happiness. "The basis for the [researchers'] conclusions are single 24-hour diet recalls from study subjects."

What's more, the study used the NOVA food classification system, which considers tofu and peanut butter to be ultra-processed and therefore unhealthy even though those foods are very nutritious.

"There's no question that consuming too many low-nutrient ultra-processed foods rich in calories, saturated fat, sodium, added sugars or a combination of these ingredients is detrimental to health," says Ward.

"When you eat an excess of highly refined carbohydrates, added sugar, calories, and saturated fat, it's likely that you don't consume enough fruit, vegetables, lean meat, seafood, soy foods, nuts, seeds, and legumes, like black beans—foods that are associated with a reduced risk of cancer and other chronic conditions."

Keeping your home plate safe

Besides eating organic foods and fresh, whole, minimally processed fare there are other strategies that can limit your exposure to chemicals when you eat, like:

Reducing your consumption of canned foods: Even if a can claims to be "BPA-free," it may still contain other bisphenols which may cause hormonal or obesogenic affects, according to a recent study in Nutrients.

Knowing your numbers: When storing food in plastic, check the recycling number on the bottom of the container. "The numbers 3, 6, and 7 represent chemical exposures that we know are of greatest concern," says Trasande. The recycling number 3 means the plastic may contain phthalate compounds, which have been shown to affect testosterone function and food metabolism. Number 6 indicates styrene, a possible carcinogen. Seven is the recycling code for bisphenols "that are known estrogens and have other consequences for obesity and other risks for human health," says Trasande.

Choosing glass over plastic when microwaving food: "When you microwave in plastic, you basically wear down the protective coating and over time there's greater contamination of the chemical components of the plastic that get right into food," says Dr. Trasande.