How are humans exposed to microplastics?

The primary routes of human exposure are inhaling plastic dust and fibers, and consuming food and beverages contaminated with micro- and nanoplastics. Exposure can be magnified up the food chain, particularly in seafood.

Do we know how much plastic humans consume weekly?

Estimates vary significantly, with aggregated data suggesting a range of 10 to 300 micrograms per week. A 2023 Korean study suggested a range of 140-310 micrograms per week. These numbers are much lower than the widely debunked 'credit card' statistic.

How are microplastics eliminated from the body?

Most ingested microplastics are eliminated through stool within 24-72 hours. Larger particles (over 10 microns) are generally expelled efficiently. Some elimination can also occur through coughing, sneezing, and urine.

What is BPA and what are phthalates?

BPA (Bisphenol A) is a chemical used in hard plastics, with related bisphenols like BPS and BPF now often used as substitutes. Phthalates are chemicals used to make plastics flexible and are found in various personal care products.

Can small particles like PM 2.5 enter the bloodstream?

Yes, particulate matter smaller than 2.5 micrometers (PM 2.5) can be inhaled deep into the lungs. Due to their size, they can potentially cross the alveolar-capillary barrier and enter systemic circulation.

Where do microplastics end up if not eliminated?

Microplastics that are not eliminated, particularly those smaller than 2.5 microns, may enter the immune system or potentially accumulate in tissues. The exact long-term consequences and accumulation sites are areas of ongoing research and concern.

Key Moments

Microplastics, PFAS, and phthalates: health risks & minimizing exposure (AMA 67 sneak peek)

Peter Attia MD

Science & Technology3 min read28 min video

Jan 20, 2025|22,019 views|573|86

Peter Attia MD Dr. Peter Attia Early Medical The Drive Podcast The Drive Longevity Zone 2

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Key Moments

TL;DR

Microplastics, PFAS, phthalates: ubiquitous, exposure routes, health risks unclear, minimize exposure.

Key Insights

Microplastics are defined as particles <5mm, with nano-plastics <1 micrometer, and are ubiquitous in air, water, and food.

BPA and similar bisphenols are used in hard plastics, while phthalates are used to make plastics flexible and are found in personal care products.

The prevalence of microplastics has surged due to increased plastic production and heightened scientific research and detection methods.

Primary human exposure routes are inhalation of plastic dust/fibers and ingestion of contaminated food and beverages, especially seafood and water.

While the exact quantity is debated, estimates suggest weekly microplastic consumption varies significantly based on diet, water source, and geography.

Most ingested microplastics are eliminated via stool, with smaller particles (<10 microns) having a higher potential for absorption, especially below 2.5 microns via lungs.

DEFINING THE CONTAMINANTS

The discussion clarifies the definitions of key plastic-associated chemicals. Microplastics are particles smaller than 5 millimeters, with nanoplastics being even smaller (<1 micrometer). These are found everywhere, from water and food to the air we breathe. Bisphenol A (BPA) and its substitutes (like BPS, BPF) are used in hard plastics, while phthalates, crucial for plastic flexibility, are also found in personal care products. Particulate matter 2.5 (PM 2.5), while often from other sources like air pollution, can include microplastics and is significant due to its ability to enter the bloodstream when inhaled.

THE RISE OF MICROPLASTICS

The increased awareness and detection of microplastics are attributed to two main factors. Firstly, the exponential growth in plastic production since the 1950s has led to more plastic waste accumulating in the environment. Secondly, there has been a dramatic increase in scientific research and publication focusing on microplastics, akin to the early rise of Bitcoin, suggesting a heightened effort to identify and study these particles. This combination means both genuine accumulation and increased observation contribute to their perceived ubiquity.

HUMAN EXPOSURE PATHWAYS

Human exposure to micro- and nanoplastics primarily occurs through inhalation of airborne plastic dust and fibers, and through consumption of contaminated food and beverages. While larger plastic particles are unlikely to be absorbed, smaller nanoplastics are of greater concern. Key sources of ingestion include seafood, salt, tap and bottled water, fruits, vegetables, and even milk, beer, and wine. Nanoplastics in soil can accumulate in plants, and bioaccumulation is magnified up the food chain, explaining higher concentrations in seafood.

QUANTIFYING INGESTION AND ELIMINATION

Estimating human consumption of micro- and nanoplastics is challenging due to significant variability based on diet, location, and water sources. Aggregated data suggests a weekly intake ranging from 10 to 300 micrograms, with some studies placing it higher. The widely circulated claim of consuming a credit card's worth of plastic weekly (around 5 grams) has been largely debunked by scientific analysis. Most ingested microplastics are efficiently eliminated through stool within 24-72 hours, as the gastrointestinal epithelium has a high barrier to absorption.

PARTICLE SIZE AND ABSORPTION

The size of micro- and nanoplastics is critical in determining their potential for absorption into the body. Larger particles, especially those over 10 microns, are generally expelled. However, particles smaller than 10 microns, and particularly those less than 2.5 microns, can potentially cross the gastrointestinal lining. Inhaled particles smaller than 2.5 microns can enter the lungs and potentially become systemic. While some excretion occurs via urine, the majority of absorbed or potentially absorbable particles are eliminated through the gut.

RISKS AND UNCERTAINTIES

The long-term health risks associated with microplastics, BPA, and phthalates are still largely uncertain and are an area of active research. The complexity of the data, incomplete information, and the constant substitution of chemicals means definitive conclusions are difficult to draw. The AMA emphasizes the need for individuals to understand the boundary conditions of exposure and make informed, risk-based decisions for themselves and their families, rather than seeking a single, simple answer to a complex problem.

Mentioned in This Episode

●Organizations

●Concepts

Minimizing Exposure to Microplastics, PFAS, and Phthalates

Practical takeaways from this episode

Do This

Consider particles smaller than 2.5 microns for pulmonary exposure and less than 10 microns for gut absorption.

Be aware that plastic dust and fibers are common exposure routes.

Consume seafood, salt, tap water, bottled water, milk, beer, and wine with awareness of potential microplastic content.

Understand that nanoplastics in soil can accumulate in plants.

The majority (99%) of ingested microplastics are eliminated through stool within 24-72 hours.

Particles larger than 10 microns are generally removed with high efficiency regardless of entry point.

For particles less than 2.5 microns, absorption is possible via gut or lungs.

Avoid This

Do not be overly concerned about large plastic particles (e.g., 5mm) as they are typically not absorbed.

Do not rely on the debunked 'credit card' worth of plastic consumption statistic.

Avoid relying solely on skin or general gut absorption for large micro/nanoplastics, as specific size thresholds apply.

Microplastic Absorption Thresholds by Body Part

Data extracted from this episode

Body Part	Maximum Size for Absorption (microns)
Pulmonary (Lungs)	< 2.5
Gut Epithelium (Theoretical)	~ 100
Gut Epithelium (Practical/Observed)	~ 10 or greater

Estimated Weekly Microplastic Consumption (Micrograms)

Data extracted from this episode

Study Source	Estimated Range (µg/week)
Aggregated Global Data	10 - 300
2021 Study (Fish, Crustaceans, Water, Beer, Wine)	4 (average from fish/seafood, likely underestimate)
2023 Korean Study	140 - 310

Common Questions

Microplastics are plastic particles smaller than 5 millimeters, with current studies focusing on those less than 1 millimeter. They are ubiquitous, found in food, water, and air, and concerns arise from their potential to enter the body and accumulate.