By Pamela Ferdinand
Chemicals found in common food packaging plastics like cling film and snack pouches may interfere with the body’s natural 24-hour sleep-wake cycle, increasing the risk of sleep disorders, diabetes, immune problems and even cancer, new research shows.
Published this month in Environment International, the study from the Norwegian University of Science and Technology is the first to show that everyday polyurethane (PUR) and polyvinyl chloride (PVC) plastics contain compounds that can disrupt the body’s internal clock (circadian rhythm) by quickly interfering with a specific cell signal (A1R) linked to sleep and light.
Unlike previous research that focused on slow, hormone-related effects, this study reveals a faster, direct impact on key “clock genes” through a different kind of biological pathway.
That means plastic chemicals may contribute to serious health problems like diabetes or cancers in more ways than scientists currently know, the researchers say.
“All of our cells follow a circadian rhythm, and the chemicals found in plastics can change that rhythm. Importantly, these chemicals are making rapid changes in our cells that can turn into sustained changes over longer periods of time,” says lead author Molly Young Mc Partland.
“Circadian rhythms are one outcome affected by the biological pathway initiated by A1R, but not the only one. This work really demonstrates how much we still have to learn about exactly how plastic chemicals can affect our cells.”
Plastic chemicals may throw our body clock off balance
Plastic compounds in everything from toys to personal care products can harm health when they leach into the environment and the human body. PVC and PUR are among the most common types of plastics, found nearly everywhere in our homes, schools and offices.
For example:
- PVC is used in food packaging like clear trays, blister packs (e.g., for gum) and shrink wraps, especially for meats and produce.
- PUR is typically found in multilayer flexible packaging as an adhesive or coating — such as in snack pouches and foil-lined food wrappers — and sometimes in foam inserts for protecting delicate items like chocolates.
Our body’s 24-hour internal clock controls sleep, metabolism, immune function, cell repair and other essential functions.
The circadian rhythm is influenced by environmental cues like sunlight, temperature, and oxygen, as well as internal signals such as hormones and metabolism.
When the rhythm is off balance, however, it has been shown to contribute to the development of serious long-term health problems like diabetes, cancer or heart disease.
Part of that may be due to the fact that plastic chemicals have long been known to release endocrine-disrupting chemicals — such as phthalates and bisphenols — that can interfere with the body’s hormone systems.
Now, this study highlights a new potential impact of disrupting the timing of two key genes that help control the body’s internal clock.
The delays are less powerful than what happens after caffeine consumption or bedtime exposure to light, the researchers note. Many factors also affect how sensitive an individual may be to both internal and external signals that control the body clock.
However, long-term, frequent exposure to plastic chemicals — especially through food packaging — makes the potential impact more concerning, the researchers say.
When repeated daily and combined with other environmental disruptions, exposure could shift the timing of key body processes that contribute to negative health impacts over time, they say.
Caffeine wakes us up, plastics do the opposite
For this study, the researchers tested chemical mixtures extracted from polyurethane and polyvinyl chloride on U20S lab cells. These cells are derived from a human bone cancer (osteosarcoma) cell line that is often used to study how biological clocks work at the cellular level.
What they found involves a type of protein called the adenosine A1 receptor (A1R), which is found on the surface of cells throughout the body, especially in the brain, the researchers say.
A1R has a well-established link to the sleep-wake cycle and uses the same pathways in the body that respond to light. In humans, caffeine blocks A1R to keep us awake — but plastic chemicals appear to quickly activate it, the researchers found.
When A1R is activated, it lowers levels of a molecule that plays a key role in keeping the circadian clock running smoothly. This, in turn, delays two “clock genes,” which are essential for maintaining the body’s daily rhythms.
The study was done in vitro (outside the body, in a lab), so the results might not apply directly to humans. However, the researchers say the findings “provide strong evidence that the chemicals in PUR and PVC plastics disrupt the molecular clock” because the effects changed with the dose and could be reversed.
The researchers measured these “clock genes” every four hours over two days and found the activity of these genes was delayed by nine to 17 minutes. When they blocked A1R using a drug, the delays disappeared.
A call for safer plastics, tighter controls
The study notes that large gaps still exist in scientists’ understanding of how plastic chemicals affect the body on a molecular level.
Only a handful of chemicals — such as acrylamide, tolylfluanid and some phthalates, which are used to make plastics softer and more durable — have been shown to disrupt core clock genes in mammals, but their mechanisms remain unclear.
More studies are needed, along with calls for safer plastics and stricter regulation of plastic chemicals, the researchers say.
“This study adds to the increasing body of evidence that plastics contain compounds causing a wide range of toxic effects,” they say.
“A fundamental shift in the design and production of plastics is essential to ensure their safety. Reducing both the number and the hazards of chemicals in plastics can decrease exposures and lessen their impacts on public health.”
Originally published by U.S. Right to Know.
Pamela Ferdinand is an award-winning journalist and former Massachusetts Institute of Technology Knight Science Journalism fellow who covers the commercial determinants of public health.
