I

A map of findings, and a map of sampling.

Read enough of this literature and a pattern emerges that has nothing to do with plastic. Particles turn up wherever a team has arrived with the right instrument. They are absent mainly from the places nobody has yet examined.

That is not a criticism of the science. It is how any young measurement field behaves. Microplastics were named in 2004 and the analytical methods matured only in the last decade, so the record we have is front loaded toward the settings that were easiest to sample and most likely to attract funding. Ocean water came first. Bottled water, indoor air, soil and human tissue came later.

Two consequences follow, and both matter when reading a headline. A new detection in an unexpected place is usually the first study of that place rather than evidence of something spreading. And the absence of a figure for a given setting almost never means the setting is clean.

With that held in mind, here is what has actually been reported, setting by setting.

II

Tap, bottled, and the gap between them.

Water carries the longest record and the widest numbers. A 2017 survey coordinated by Orb Media tested tap water from five continents and reported synthetic fibers in most samples, with the highest rates in the United States. It was journalism built on laboratory work rather than a peer reviewed paper, and it set the agenda for everything that followed.

Bottled water has generally returned higher counts than tap in the studies that compared the two. The 2018 analysis led by Sherri Mason at the State University of New York at Fredonia examined 259 bottles across 11 brands and 9 countries and reported an average of 325 particles per liter, with 93 percent of bottles showing some contamination. Polypropylene, the polymer used in bottle caps, was the most common material identified, which pointed at the container rather than the source water.

The 2024 study from Columbia and Rutgers, published in the Proceedings of the National Academy of Sciences, reported roughly 240,000 fragments per liter across three United States brands. The jump is almost entirely a jump in what the instrument could see: about 90 percent of those fragments were nanoplastics, below the size class the 2018 work was equipped to find.

One finding cuts the other way and is rarely quoted. The World Health Organization noted in its 2019 review that conventional drinking water treatment, where it is well operated, removes a high proportion of particles. Treated tap water is not the worst case in this literature. In most of the direct comparisons it is the better one.

III

Salt, shellfish, and the container.

Food splits into two questions that often get merged. What was in the ingredient, and what arrived from the packaging or the preparation.

On ingredients, salt is the clearest case. A 2018 analysis published in Environmental Science and Technology examined 39 brands from 21 countries and reported particles in 36, with sea salt generally higher than rock or lake salt, which tracks the water it came from. Shellfish are the second clear case, for a mundane reason: mussels and oysters are eaten whole, digestive tract included, while a fish fillet has had its gut removed before it reaches a plate.

On packaging and preparation, several findings have landed hard. A 2019 study at McGill University reported that a single plastic tea bag steeped at brewing temperature released billions of micro and nano sized particles into one cup. A 2020 paper in Nature Food, from Trinity College Dublin, reported that polypropylene infant feeding bottles released substantial numbers of particles during the standard sterilize and shake preparation, with higher temperatures producing more. Later work has examined what heating a plastic container in a microwave releases.

Beer, honey, sugar, rice and several fruits and vegetables all appear in the record too, though the early studies on some of them drew method criticism that has not entirely been resolved. Treat any single food figure as provisional until a second group has reproduced it with proper blanks.

IV

The route that arrived late.

Air was studied years after water, and several researchers now argue it deserved to come first.

Work led by Rachid Dris in Paris reported indoor fiber deposition of roughly 1,600 to 11,000 fibers per square meter per day, considerably higher than the outdoor rates measured alongside it. Homes are full of textiles, and textiles shed whether or not they are in a washing machine.

Outdoors, the surprise was reach. A 2019 paper in Nature Geoscience reported particles falling on a remote high altitude catchment in the French Pyrenees at around 365 per square meter per day, with air mass modeling indicating transport of up to about 95 kilometers. A 2020 paper in Science estimated that more than a thousand tons are deposited each year across protected areas of the western United States, most of it arriving on the wind rather than from any nearby source.

The practical consequence is a shift in how intake is framed. Several assessments now treat inhalation as a route comparable in scale to swallowing, and for some people possibly larger, because a person breathes continuously and most of that breathing happens indoors. It has not displaced diet in the literature. It has stopped being a footnote to it.

V

The settled version of air.

Household dust is the same story as indoor air, one step later. What is suspended eventually lands, and the floor of a room accumulates what the room is made of.

Studies that sample indoor dust directly consistently report synthetic fibers as a large share of what is present, drawn from clothing, bedding, upholstery, curtains and carpet. Polyester dominates, which is unsurprising given how much of the modern textile supply it accounts for. Fragments from coatings, packaging and worn plastic objects appear alongside the fibers.

Dust matters for a reason that has little to do with adults. Small children spend time at floor level and put their hands in their mouths, and several exposure assessments treat that as a meaningful route on its own. It is also the setting where ordinary domestic habit has the clearest effect on what is measured, since ventilation, vacuuming with a fine filter and damp cleaning all change the result.

This is the part of the subject where the literature and common sense point the same way, and where the available actions are unglamorous and cheap.

VI

The far places, and the near ones.

Particles have been reported in Arctic sea ice, in freshly fallen Antarctic snow, in sediment from the deepest ocean trenches, and in snow collected near the summit of Everest at around 8,440 meters, the highest such finding published. Agricultural soil is an active area too, since sewage sludge applied as fertilizer carries what a wastewater plant filtered out of the water.

Human samples arrived last. A 2022 paper in Environment International examined blood from 22 anonymous donors and identified polymer particles in 17, most commonly polyethylene terephthalate. A 2021 study reported particles in human placental tissue, and a 2022 study reported them in lung tissue from surgical patients. Each of these was a small first study, and each set of authors called for larger work.

The distinction to hold on to is the one between detection and effect. These papers establish that particles can be found in human samples with current methods. They do not, on their own, describe what that presence does, and their authors were careful not to claim otherwise. Studies referenced here were conducted independently and did not involve any specific Codeage product.

The World Health Organization, reviewing the drinking water evidence in 2019, found it limited and inconsistent between methods and placed standardized measurement at the top of its list of research needs. That work is still under way, which is the honest end point for a page about where things have been found.

VII

Where this fits.

A house that formulates for daily use has to read the conditions people actually live in, which is why a subject like this one belongs in the Codeage library. It sits nearest Systemic Balance, the fourth pillar of The Longevity Code. A pillar names a location in a framework. It describes a category, not an outcome for any reader.

One thing bears repeating, because this subject attracts claims that run ahead of the evidence. No dietary supplement is described in the research as acting on microplastics, and nothing on this page should be read that way. Codeage does not make that claim and will not.

What a house can do is be precise about what is known, name the limits plainly, and formulate around ingredients researched in their own right.