Hot Water and Plastic: How Everyday Items Release Trillions of Nanoparticles

When exposed to hot water, common plastics shed trillions of nanoparticles, raising environmental and health questions.

By Medha deb

Created on Sep 27, 2025

When exposed to hot water, common plastics shed trillions of nanoparticles, raising environmental and health questions.

Plastic is part of our everyday lives, found everywhere from kitchen shelves to supermarket aisles. Yet, its durability comes at a hidden cost: microscopic plastic particles, too minuscule to see, are released during everyday activities—especially when plastics meet hot water. Recent scientific research, led by the National Institute of Standards and Technology (NIST), has illuminated a startling fact: trillions of plastic nanoparticles are released from ordinary consumer products each time they’re exposed to hot water, such as when making tea or coffee.

What are Nanoplastics?

Nanoplastics are plastic fragments less than 0.001 millimeters (1,000 nanometers) in diameter. For scale, even a single human hair can be more than 1,000 times thicker than a nanoplastic particle. Unlike larger microplastics, nanoplastics are so small they may be able to enter human cells, potentially disrupting biological functions. This ultra-small size also allows them to spread widely throughout both natural and built environments.

Microplastics: Particles smaller than 5mm but larger than 1µm (1,000nm).
Nanoplastics: Particles smaller than 1µm (1,000nm), down to molecular scale.

Key Findings from the Study

The NIST-led study set out to analyze commonly used household plastics in real-world settings, focusing on how much plastic is released into water when these items are exposed to different temperatures.

Tested Items:
- Food-grade nylon bags (commonly used for boiling or wrapping foods, like tea bags)
- Disposable coffee cups lined with low-density polyethylene (LDPE)
Related: Microplastics in Humans: Understanding the Hidden Risks
Temperature: The release of nanoplastics increases rapidly as water temperature rises—peaking at around 40°C (about 100°F) and holding steady up through boiling.
Scale: A single liter of hot water in contact with these plastics can contain trillions of nanoparticles, each ranging from 30–80 nanometers in size.
Material Differences: Food-grade nylon released seven times more nanoparticles than LDPE-lined cups under the same conditions.

How Were Nanoplastics Detected?

Detecting particles that small isn’t trivial. The researchers adapted advanced atmospheric science methods to analyze the plastic-laden water. The process involved:

Creating a fine mist from the water sample
Drying the mist to isolate solid particles
Sorting particles by size and electrical charge
Counting the particles using specialized sensors and computer algorithms, which expanded the nanoparticles to detectable sizes by exposing them to alcohol vapors

This combined approach ensured that the results were reliable and represented what typical consumers might encounter in daily life.

Temperature and Nanoplastic Release: What’s the Relationship?

One of the study’s most surprising discoveries was the strong temperature dependence of nanoplastic shedding:

At low temperatures, plastics release very few nanoparticles.
Above 40°C (104°F), the number of released nanoparticles spikes quickly, and remains high at temperatures up to boiling (100°C, or 212°F).
This means that any activity involving hot water and plastic—from brewing tea to heating baby bottles—results in significant nanoparticle release.

Which Plastics Shed the Most Nanoparticles?

The study compared two widely used consumer plastics:

Plastic Type	Common Use	Nanoparticles Released (Relative to Each Other)
Food-Grade Nylon	Tea bags, food wrappers	High (7x more than cups)
LDPE-Lined Cups	Disposable coffee/tea cups	Lower than nylon

It’s important to note that the results likely extend to a wide range of everyday food packaging and utensils made from similar materials.

How Big Are the Nanoplastics?

Most of the nanoparticles released from hot water contact with plastics are between 30 and 80 nanometers in size. Particles smaller than 100 nanometers are concerning because they may be small enough to enter human cells or even cross biological barriers like the gut or blood-brain barrier, although this pathway has not yet been fully proven.

How Much Plastic Is Actually Released?

Although the particle counts per liter are staggering, the overall mass of plastics released in these scenarios is still small relative to accepted safety limits. For example, the US Food and Drug Administration (FDA) allows food-grade nylon to lose up to 1% of its mass under hot water conditions. The NIST study found that, in their tests, less than 0.1% of the material’s mass was lost—ten times below the FDA’s threshold for safety.

What Does This Mean for Health?

Currently, no definitive evidence links the ingestion of nanoplastics—at the concentrations observed in this study—with specific health risks in humans. However, researchers emphasize key points:

Nanoplastics are found everywhere, from polar ice to deep oceans, but the smallest particles were, until recently, not detectable.
The main concern stems from the possibility that nanoplastics, due to their small size, may enter cells and disrupt cellular function.
No in vivo health effects have yet been confirmed for these particular particles, but the unprecedented exposure from daily use is raising new questions for toxicologists and public health experts.

How Do Nanoplastics Enter the Environment?

Nanoplastic pollution is not limited to food and drink:

Household plastics—such as laundry fibers, packaging, and kitchenware—can shed nanoplastics into wastewater.
Environmental studies have detected micro- and nanoplastics in rivers, lakes, the ocean, and even in rain and polar snow.
Improper disposal of plastics and widespread littering exacerbates the spread of these invisible particles.

Regulation and Testing: What Safeguards Are in Place?

The FDA and other international bodies regulate what plastics are considered safe for food contact. Testing traditionally focuses on total plastic mass loss, and less on the particle count or size:

The FDA requires that plastics in food applications do not leach harmful levels of chemicals or exceed set mass loss thresholds.
For food-grade nylon, mass loss must remain below 1% under elevated temperatures. The NIST study found releases about ten times below that.
For some plastics (like LDPE), standardized testing is less mature, but new research is encouraging further development of protocols to measure nanoscale particle release directly.

Current Limitations and Research Needs

There is no universal test for quantifying nanoplastics from all types of food contact plastics.
Research is ongoing to understand the potential health effects, environmental behavior, and mechanisms by which nanoplastics interact with biological organisms.
The technology used in the NIST study may serve as a model for developing such protocols in the future.

What Can Consumers Do?

Minimize hot water contact with plastic: Avoid directly pouring boiling water into plastic containers or using single-use plastic-lined items for hot food and drinks when alternatives are available.
Switch to glass, stainless steel, or ceramic: For hot beverages and food preparation, heat-resistant alternatives reduce potential nanoplastic exposure.
Advocate for research and regulation: Support calls for deeper scientific analysis and the creation of safer, more sustainable food packaging options.
Reduce single-use plastics: Opt for reusable products and proper disposal.

Frequently Asked Questions (FAQs)

Q: Are nanoplastics dangerous to human health?

At present, there is no clear scientific evidence linking nanoplastics in food or drink to specific adverse health effects. Because these particles are extremely small, scientists are concerned that they could, in theory, enter cells or disrupt cellular function, but more research is needed to clarify their impact.

Q: How many nanoplastics are released from a single cup?

Studies have shown that simply pouring hot water into a nylon tea bag or an LDPE-lined coffee cup can result in the release of trillions of nanoplastic particles per liter of water. The exact amount depends on the type of plastic, the temperature, and duration of exposure.

Q: Do cold drinks cause the same plastic release?

No, the number of nanoparticles shed into water is much higher for hot liquids. The release increases dramatically with water temperature, becoming significant at 40°C and peaking around boiling temperature.

Q: Are there safe plastic options for hot foods and drinks?

While most food-grade plastics are regulated for overall safety and must meet strict standards for chemical release and physical performance, no plastic is entirely immune to shedding nanosized particles when exposed to high temperatures. Using alternatives like glass or stainless steel is recommended for hot applications.

Q: What does this mean for environmental pollution?

The findings add to mounting evidence that plastics, especially nanoplastics, are pervasive in our environment. They can be transported through air, water, and soil, and are likely to accumulate over time, posing unknown risks for wildlife and ecosystems as well as humans.

Conclusion: Rethinking Everyday Plastics

The discovery that plastics routinely shed trillions of invisible particles when subjected to everyday conditions such as making tea or coffee is reshaping our understanding of plastic pollution. While immediate health risks are unconfirmed, the research highlights the importance of transparency, further study, and innovation in both consumer habits and product development.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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