There is a natural tendency for people to equate natural with safe and synthetic with dangerous, but there is no scientific basis for that sentiment. In fact, 4 out of the 5 most toxic chemicals are natural.
S. Cotton, Handle with care — the world’s five deadliest poisons, University of Birmingham Chemistry Department, The Conversation, 2016
This misconception may be one reason people assume synthetic materials like plastic must be toxic, even in the absence of evidence to support the idea.
Are Plastics Toxic?
No, they are not. Are you convinced yet? Let’s take a look at the science.
On 12 May 2021, the National Observer reported on the Canadian federal government’s announcement about the addition of “plastic manufactured items” as toxic substances under Schedule 1 of the Canadian Environmental Protection Act (CEPA). The minister responsible was Steven Guilbeault. That was quite an outlandish and arrogant decision given that we have decades of data to the contrary and that regulatory bodies the world over have approved plastic utensils, food containers, blood bags, and implantable devices (hips, knees, pacemakers). Yet somehow this former Greenpeacer feels that he knows better than every scientist in the world. It reminded me of the story of King Canute.
“Canute set his throne by the seashore and commanded the incoming tide to halt and not to wet his feet and robes. Yet continuing to rise as usual [the tide] dashed over his feet and legs without respect to his royal person.”
On 16 November 2023, a Canadian Federal Court justice overturned the federal government’s 2021 declaration that labelled all plastic items as toxic, citing overreach under the Environmental Protection Act. The justice stated that the evidence “has not shown that there is a reasonable apprehension of harm for every plastic manufactured item.”
And so it is, that no matter how powerful or arrogant a person may be, their declarations do not stand up in the face of reality. Politicians do not define what is toxic; only scientists can do that, and they have indeed studied the subject in detail. The older method you may have heard of is the LD50, which is the dose fed to a rat or mouse that kills 50% of the test group. It is a measure of acute toxicity. The longer-term, so-called “chronic” toxicity is measured by feeding the test animals for weeks or months to determine the maximum amount that can be ingested repeatedly with no observable effect. This is known as the no-observed-adverse-effect level, or NOAEL for short. How do plastics compare to other substances we routinely come into contact with?
As we can see, plastic materials are “non-toxic” and some of the safest materials we have. You could eat a cup of plastic pellets every day for months, and nothing would happen. The US EPA’s Toxic Substances Control Act even created the so-called “polymer exemption” in recognition of the exceptional safety of plastics compared to other classes of substances. Since polymer molecules are so large, they cannot migrate (move around), which makes them intrinsically safer than small molecules.
The NOAEL levels were determined using ingestion of plastic pellets that are defined as microplastics, meaning they are 5 mm or smaller. This means that the toxicity — or should I say, the non–toxicity — of microplastics has been well-established experimentally for many years.
When animals ingest plastic, it passes right through without any effect, according to several studies, such as this one on PVC, nylon, UHMWPE, PS, MDPE, and fish.
“In conclusion, the dietary exposure of S. aurata to 6 common types of virgin microplastics did not induce stress, alter the growth rate, cause pathology, or cause the microplastics to accumulate in the gastrointestinal tract of the fish.”
B. Jovanović, Virgin microplastics are not causing imminent harm to fish after dietary exposure, Marine Pollution Bulletin, 130, pp. 123–131, 2018
That study also highlighted other studies that had not been performed properly, thus creating unjust concern. We will see later that this is a recurring theme. Researchers conduct experiments in ways designed to produce scary but invalid results.
“However, in previous experimental setups, fish were usually exposed to unrealistically high concentrations of microplastics, or the microplastics were deliberately contaminated with persistent organic chemicals; also, in many experiments, the fish were exposed only during the larval stages.”
Here is another study confirming no effect from microplastics when experiments are done properly under realistic conditions.
“However, after one month of detoxification, no MPs were found in the gastrointestinal tracts of fish, reflecting no long-term retention of MPs in Sparus aurata digestive system. According to results from this study, exposure of fish to MP enriched diets does not affect fish size neither the Fulton’s condition index as both parameters increased with time in all treatments (control, virgin and weathered)”
C. Alomar et al., Microplastic ingestion in reared aquaculture fish: Biological responses to low-density polyethylene controlled diets in Sparus aurata, Environmental Pollution, 280 (1), 2021
And another two:
“No mortality occurred during the feeding trial and there were no apparent signs of significant distress or adverse effects on the fish. We found no significant differences in growth performance…”
“No accumulation of HDPE was detected in fish collected 24 h post-feeding…”
X. Lu et al., Chronic exposure to high-density polyethylene microplastic through feeding alters the nutrient metabolism of juvenile yellow perch (Perca flavescens), Animal Nutrition, 9, 2022
C. Alomar et al., Microplastic ingestion in reared aquaculture fish: Biological responses to low-density polyethylene controlled diets in Sparus aurata, Environmental Pollution, 280 (1), 2021
We are told that plastic pellets (nurdles) and microplastics poison and accumulate in fish, but science shows the opposite. In reality, they pass right through.
There was a study claiming harm, but it was retracted after those scientists were reported for manipulation of data, which led to an investigation.
O. Lönnstedt & P. Eklöv, Environmentally relevant concentrations of microplastic particles influence larval fish ecology, Science, 352, pp. 1213–1216, 2016
There has been a lot of talk about phthalates, which are used to soften a small portion of plastics. They are not used in polyethylene, polypropylene, PET, polycarbonate, polystyrene, ABS, or most plastics you use. Phthalates are not used in PVC pipes because they are made of rigid, unplasticised PVC. Rather, they are used to soften some PVC products that need to be soft. There have been comprehensive studies spanning decades. We know that there is no cause for alarm because exposure due to plastics and various other sources is extremely low.
This review of the science around phthalates found no reason for concern, agreeing with the FDA’s position.
“Analysis of all of the available data leads to the conclusion that the risks are low, even lower than originally thought, and that there is no convincing evidence of adverse effects on humans. Since the scientific evidence strongly suggests that risks to humans are low, phthalate regulations that have been enacted are unlikely to lead to any marked improvement in public health.”
M. A. Kamrin, Phthalate risks, phthalate regulation, and public health – a review, Journal of Toxicology and Environmental Health, Part B, 12, pp. 157–174, 2009
Exposure is far higher for workers in PVC plants, as one would expect. However, high exposure is also found for massage therapists, nail and beauty salon employees, perfume salespeople, and people taking certain medications containing phthalates. No one talks about those other exposure sources, perhaps because their real interest is not in phthalates but in attacking plastics. In the case of perfume, you literally spray phthalate right on the skin, which is far worse than holding a piece of plasticised PVC because, in the latter case, the additive only comes out of the plastic very slowly.
P.-C. Huang et al., Characterization of phthalates exposure and risk for cosmetics and perfume sales clerks, Environmental Pollution, 233, pp. 577–587, 2018
BPA is similar in that there are decades of studies and an agreement that exposure from plastics and all other BPA sources is far below recognised safe limits.
“In general, the total exposure to BPA is several orders of magnitude lower than the current tolerable daily intake of 50 μg/kg bw/ day.”
T. Geens et al., A review of dietary and non-dietary exposure to bisphenol-A, Food and Chemical Toxicology, 50, pp. 3725–3740, 2012
BPA can form at extremely low concentrations when polycarbonate plastic is left in contact with water, but the amounts are too low to present a problem.
“BPA was only detected in a sample from a polycarbonate container at levels well below the EFSA total daily intake value.”
C. Rowell et al., Is container type the biggest predictor of trace element and BPA leaching from drinking water bottles?, Food Chemistry, 202, pp. 88–93, 2016
Other sources of BPA, like thermal paper, are much more of a problem, but there is little mention of that in the press, presumably because the concern is not really about BPA but more about finding ways to unjustly demonise plastics.
Having established that plastics and common additives for plastics are not toxic, the next topic is microplastics. There is a perception that plastic particles are a new, previously unrecognised threat to humanity and animals. Is that really the case?
Are Particles Dangerous?
Probably the first question to address is whether we need to be concerned about the health effects of particles in general. The short answer is that yes, particles can and do cause serious health effects, but as with any topic, there is a little more to it than that. The threat level depends on the type of particle, the size, and the dose.
Fine particles under 10 microns and especially under 2.5 microns in size can cause health problems. A review article stated:
“The World Health Organization (WHO) estimated that in the year 2012, ambient air pollution was responsible for 3.7 million annual deaths (which represents 6.7 % of the total deaths), causing worldwide 16 % of deaths for lung cancer, 11 % for chronic obstructive pulmonary disease, more than 20 % for ischemic heart disease and stroke and 13 % for respiratory infection.”
P. M. Mannucci et al., Effects on health of air pollution: a narrative review, Internal & Emergency Medicine, 10 (6), pp. 657–62, September 2015
“Nine out of 10 people breathe air that does not meet World Health Organization pollution limits. Air pollutants include gasses and particulate matter and collectively are responsible for ∼8 million annual deaths. Particulate matter is the most dangerous form of air pollution, causing inflammatory and oxidative tissue damage.”
J. T. Pryor et al., The Physiological Effects of Air Pollution: Particulate Matter, Physiology and Disease, Frontiers in Public Health, 10, (82569), 2022
In areas with heavy pollution, health problems exist, but when particle concentrations are lower, the body’s natural defence system can cope. Think of it like a castle wall. If a few invaders try their luck, then they are easily repulsed. But if an onslaught of millions were to try, then they would overrun the castle walls. This makes it plain why dose is so important in the field of toxicology. What may be benign or even beneficial at low concentrations will almost certainly become a problem at extremely high doses.
Given that particles can indeed pose a threat, is there reason to be especially concerned about plastic particles? What are the concentrations and are they toxic? We have all heard the scare stories, but remember that in every chapter so far, science has completely contradicted the message that the public hears. Since this is such an emotive topic, I have read over 500 studies on this one subject, which may well be the most in-depth, independent, and unfunded review on microplastics. That was a painful experience for me, but the good news is that scientists already have all the answers.
Dust Particles & Health
While we are talking about dust, what is in it and how dangerous is the plastic in it compared to the many other types of particles?
J. A. Styles & J. Wilson, Comparison between in vitro toxicity of polymer and mineral dusts and their fibrogenicity, The Annals of Occupational Hygiene, 16 (3), pp. 241–250, November 1973
IARC Monographs Volume 100 A Review of Human Carcinogens, World Health Organization, 2012
Note that I cited a study from 1973, over 50 years ago, just to highlight the point that this is not some new, previously unrecognised topic. Quite the reverse, in fact — we have decades of testing right up to the present on dust and plastic particles.
While plastics are found to be safe, what may surprise many is just how dangerous some of the other particles are. Quartz is one of the most common rocks. When we go to the beach, we merrily bathe in the sunlight, which can give us cancer while breathing in quartz dust, which can also give us cancer. Workers are exposed to dangerous levels of quartz, including those in factories, sawing quartz countertops, and even farmers ploughing the fields can be exposed to levels above recognised safe limits.
“Twelve of 138 respirable dust measurements (9%) and 18 of 138 respirable quartz measurements (13%) exceeded commonly used occupational exposure limits of 2 mg-3 and 100 µg m-3, respectively. The highest time weighted average respirable quartz concentration of 626 µg m-3 was during wheat planting activities. Fifty-seven percent of the respirable quartz measurements exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) of 25 µg m-3. Quartz percentages of the respirable dust ranged from 0.3 to 94.4% with an overall median of 13.4%.”
A. J. Swanepoel et al., Quartz exposure in agriculture: literature review and South African Survey, Annals of Occupational Hygiene, 54 (3), pp. 281–292, 2010
“China appears to have the highest burden of silicosis, with more than 500,000 cases recorded between 1991 and 1995, and 6000 new cases and more than 24,000 deaths reported annually.”
K. Steenland & E. Ward, Silica: A Lung Carcinogen, CA: A Cancer Journal for Clinicians, 64, pp. 63–69, 2014
“Wood dust was classified as carcinogenic to humans.”
“Strong and consistent associations with cancers of the paranasal sinuses and nasal cavity have been observed both in studies of people whose occupations were associated with wood-dust exposure and in studies that directly estimated wood-dust exposure.”
IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 62
https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/wood-dust
S. D. Stellman et al., Cancer Mortality and Wood Dust Exposure Among Participants in the American Cancer Society Cancer Prevention Study-II (CPS-II), Journal of Industrial Medicine, 34, pp. 229–237, 1998
Somehow, there seems to be very little concern over the proven dangerous particles, like quartz and wood dust, that cause health problems and even mortalities.
So, what about the plastic fraction of the dust we breathe? How many deaths have been attributed to that? The answer is zero. The portion of dust particles deemed as respirable is below 10 microns in size, abbreviated PM10, and the plastics contribution to that is negligible.
“Therefore, the [microplastic] MP concentration in the air has a negligible contribution to the PM10 levels, even at the 95th percentile.”
Nur Hazimah and Mohamed Nor, Lifetime Accumulation of Microplastic in Children and Adults, Environmental Science & Technology Journal, 55 (8), pp. 5084–5096, 2021
A comprehensive breakdown of the troublesome fraction of dust below 10 microns in particle size (PM10) globally highlighted the sources of concern for health. Plastics were not even mentioned as a problem.
A. Mukherjee & M. Agrawal, World air particulate matter: sources, distribution and health effects, Environmental Chemistry Letters, 15, pp. 283–309, 2017
It is very clear where PM10 dust comes from, and it is not plastics. Although there are actual sources of toxic and carcinogenic (cancer-causing) dust listed in the table, no one appears interested in discussing those genuine problems.
This information highlights the double standard applied to plastics. We are happy to ignore real, proven dangers completely and instead obsess over imaginary ones. As a scientist, I prefer to worry over what deserves my attention and not spend time and money on matters that don’t matter.
What about indoor particles and the contribution from plastic? Once again, the plastic fraction of dust is so low that it is not even mentioned in most studies. Other sources of particles, such as skin particles, quartz, spores, and even cooking, dominate the scene.
“The highest mean number concentrations were due to complex cooking, producing average number concentrations of 35,000–50,000 cm−3, compared to 12,000 cm−3 outdoors and less than 3500 cm−3 indoors when no sources were observed. A strong contribution of the vented gas-powered clothes dryer was also noted (30,000 cm−3).”
L. Wallace, Indoor Sources of Ultrafine and Accumulation Mode Particles: Size Distributions, Size-Resolved Concentrations, and Source Strengths, Aerosol Science & Technology, 40, pp. 348–360, 2006
For comparison, the concentration of plastic in indoor dust was under 0.001 cm-3.
M. A. Bhat, Airborne microplastic contamination across diverse university indoor environments: A comprehensive ambient analysis, Air Quality, Atmosphere & Health, 9, 2024
Yet again, we find that the focus on plastic particles is not justified by the evidence.
Microplastics Exposure
We have been told that we eat a credit card of plastic per week. The WWF tells us that based on a study they paid for. Other non-profits and the media repeated the claim. When considering evidence, it is always best to check other sources of information, preferably impartial ones.
So, what does the best impartial scientific study have to say about microplastic ingestion by humans? The authors of that study specifically state that the WWF study is wrong; in fact, it is so wrong due to a “mistake” that one can hardly believe it. So, how much plastic do we ingest?
The answer is 184 ng per person per day, or 0.000000184 g.
To help you (and me) to visualise that amount, a grain of salt weighs 60,000 nanograms.
Remember, the WWF says that we ingest 5 g per week, which is what a credit card weighs, when the actual amount is just 0.0000013 g per week. Meaning that it would actually take tens of thousands of years to ingest a credit card’s worth of plastic!
Did the WWF, the other NGOs, or the media retract their erroneous claim?
Of course not. Good news doesn’t sell, and where’s the profit in truth?
This is yet more evidence that many so-called “environmental” groups have abandoned the environment in favour of the gravy train — more on that topic later.
The newer, independent review study listed all the sources of microplastics ingested, including fish, molluscs, crustaceans, tap water, bottled water, salt, beer, milk, and the air. Amounts for the individual items listed were extremely low, in the region of 1 x 10-8 to 1 x 10-10 mg/person/day.
Nur Hazimah and Mohamed Nor, Lifetime Accumulation of Microplastic in Children and Adults, Environmental Science & Technology, 55 (8), pp. 5084–5096, 2021
They concluded that amounts are incredibly low compared to inorganic particles.
“Comparing our findings with the intake of other particles, MP mass intake rates are insignificant, as they make up for only 0.001% of these particles.”
This exposes the folly of obsessing over plastic particles. They are 0.001% of particles we ingest and non-toxic, whereas the other 99.999% contain proven toxins and carcinogens, meaning substances proven to cause cancer in humans. Ingestion of those other particles, including cancer-causing crystalline silica, is 40 mg per person per day, 200,000 times more than it is for plastic. Anyone focused on the plastic particles and not the real, present danger is exhibiting an irrational fear of plastic.
J. J. Powell et al., Origin and fate of dietary nanoparticles and microparticles in the gastrointestinal tract, Journal of Autoimmunity, 34, pp. 226–233, 2010
There has been an extreme amount of attention on the topic of microplastic in PET bottles. That topic has been studied in huge detail. The particles are safe and they come from the abrasion of the cap made of FDA-approved plastic.
“Microplastic contamination levels in the water were found to increase as the bottle cap is opened and closed repeatedly. The rate of generation of particles with bottle opening and closing cycles (553 ± 202 microplastics/L/cycle) is adequate to account for the total particle density in the water. This clearly demonstrates that the abrasion between the bottle cap and bottleneck is the dominant mechanism for the generation of microplastic contamination detected in bottled water.”
T. Singh, Generation of microplastics from the opening and closing of disposable plastic water bottles, Journal of Water & Health, 19.3, pp. 488, 2021
The creation of particles by abrasion can be solved simply by redesigning the screw threads.
A study compared microplastic amounts in one-way PET bottles, returnable PET bottles, glass bottles, and paper-based beverage cartons. They found an amount so low that statistically, they were not more than the control sample, which was ultra-pure filtered deionised water. This is a very important point. So many other studies detect microplastics from, e.g. bottled water, but do not compare the amounts to those found in water that was never in a PET bottle. Dust is everywhere, and methods are now so sensitive that you can detect anything you want anywhere you want. The proposal to avoid PET bottled water makes little sense because particles are there even with no water at all or when a glass bottle or paper-based carton is used instead of PET. They are present in effluent water, ocean water, lake water, river water, canal water, groundwater, and tap water as well because dust is everywhere.
“The average microplastics content was 118 ± 88 particles/l in returnable, but only 14 ± 14 particles/l in single-use plastic bottles. The microplastics content in the beverage cartons was only 11 ± 8 particles/l. Contrary to our assumptions we found high amounts of plastic particles in some of the glass bottled waters (range 0-253 particles/l, mean 50 ± 52 particles/l). A statistically significant difference from the blank value (14 ± 13) to the investigated packaging types could only be shown comparing to the returnable bottles (p < 0.05)”.
D. Schymanski et al., Analysis of microplastics in water by micro-Raman spectroscopy: Release of plastic particles from different packaging into mineral water, Water Research 129, pp. 154–162, 2018
A. A. Koelmans et al., Microplastics in freshwaters and drinking water: Critical review and assessment of data quality, Water Research, 155, pp. 410–422, 2019
In any case, amounts of microplastic from PET bottled water are extremely low, around 0.0000001% by weight food contact approved polyethylene, and the level of additives found was even lower, around 0.0000000001%. The media frenzy around these insignificant amounts may well have been fuelled and funded by competitors selling alternative containers made of glass or metal, as there is no rational basis for it.
“Exposure estimations based on the reported microplastic amounts found in mineral water and the assumption of total mass transfer of small molecules like additives and oligomers present in the plastic would not raise a safety concern. Available toxicokinetic data suggests that marginal fraction of the ingested low amount of microplastics can be absorbed, if at all, the conclusion is very likely that the reported amounts present in bottled mineral water do not raise a safety concern for the consumer. Considering the use of plastic materials in our daily life, occurrence of microplastics in beverages is likely a minor exposure pathway for plastic particles.”
F. Welle & R. Franz., Microplastic in bottled natural mineral water — literature review and considerations on exposure and risk assessment, Food Additives & Contaminants: Part A, 35 (12), pp. 2482–2492, 2018
“The estimated daily intake of MPs due to the consumption of bottled water falls within the 4–18 ng kg−1 day−1 range, meaning that exposure to plastics through bottled water probably represents a negligible risk to human health.”
V. Gálvez-Blanca et al., Microplastics and non-natural cellulosic particles in Spanish bottled drinking water, Scientific Reports, 14, 2024
There is no threat according to properly done, peer-reviewed science.
Microplastics Accumulation
One might wonder what the long-term exposure adds up to over a lifetime.
That, too, can be calculated.
We ingest 0.0000013 g per week, and there are around 3600 weeks in 70 years.
So, the total lifetime exposure to microplastics by ingestion is less than 0.005 g.
The vast majority (~99.7%) of small particles ingested pass right through us.
So, we can calculate the total amount not expelled over 70 years as <0.000015 g.
We also know that even those tiny amounts not expelled are attacked by our body’s defences, degraded, and removed.
T. C. Liebert et al., Subcutaneous Implants of Polypropylene Filaments, Journal of Biomedical Materials Research, 10 (6), pp. 939–951, 1976
Once more, we find that there is no valid reason to be concerned.
Going back to NOAEL, the amount of plastic that can be eaten every day with no effect, which was 50–150 g per day, let us compare that to the actual exposure just mentioned, which is 0.0000002 g. This means that our actual exposure is hundreds of millions of times less than the safe limit.
Anyone genuinely worried about particles should instead focus on the 200,000x greater amount of inorganic particles (with around 1 kg ingested per lifetime) that contain harmful substances, like lead, mercury, and arsenic, plus cancer-causing quartz, than the tiny fraction of non-toxic plastic.
Microplastic Removal
Have you seen any of the articles where high school students win a prize for inventing a new way to remove microplastics? One such article talks about using ferrofluid to absorb the particles and then remove them with a magnet. I’m not sure who was on the prize committee, but they are clearly not proper scientists.
We do not need a new way to remove particles; we have a method that is cheap and works very well. It is called a filter and has been used for centuries. When removing particles from water in a water treatment plant, they coagulate, then filter the water, and that works just fine.
“Results show that on average 89% of microplastics and 81% of synthetic fibres (≥63 μm) are retained in water treatment in absence of coagulant. Better final removal efficiency of microplastics (97%) and synthetic fibres (96%) was observed in drinking water with coagulation treatment.”
A. Velasco et al., Contamination and Removal Efficiency of Microplastics and Synthetic Fibres in a Conventional Drinking Water Treatment Plant, Frontiers in Water, 4, 2022
People are being rewarded for inventing new, but worse, “solutions.”
Rebranding Dust
Thought to have been coined by Professor Richard Thompson in his article “Lost at Sea: Where Is All the Plastic?” published in 2004, the term “microplastic” was in fact first used well over a decade earlier, in 1990, so Thompson is not actually the discoverer after all.
P. G. Ryan & C. L. Moloney, Plastic and other artefacts on South African beaches – temporal trends in abundance and composition, South African Journal of Science, 86, pp. 450–452, 1990
The University of Portsmouth is very proud of Thompson, who has made a career as the supposed father of microplastics. Here’s a quote from their website.
Sounds ominous, doesn’t it?
Now try replacing the word “microplastic” with the word “dust,” and it soon becomes clear just how silly this microplastic hysteria is. We’ve found dust! Is that worthy of the news? If I call the Editor-in-Chief of The New York Times and tell him I have found dust on my keyboard, will it make the front page? Probably not. In fact, they would likely laugh in my face; that is what they should do when people find plastic dust in some new place.
Having said that, here is an actual headline from National Geographic.
E. Napper et al., Reaching New Heights in Plastic Pollution—Preliminary Findings of Microplastics on Mount Everest, One Earth, 3 (5), pp. 621–630, 2020
My response to that was:
“Since when was ‘I found dust’ news? Dust is everywhere.”
Here’s another “we found dust” headline.
A. J. Jamieson et al., Microplastics and synthetic particles ingested by deep-sea amphipods in six of the deepest marine ecosystems on Earth, The Royal Society, Open Science, 6, 180667, 2019
Why are 99.999% of particles called “dust” and the other 0.001% of particles we ingest called “microplastics”? This clever rebranding has enabled NGOs and some scientists to cash in on our fear.
If you do a Google search for the terms “micrometal,” “microwood,” “microquartz,” and “micropaper,” there are no hits (and they show up as spelling mistakes on my computer) because particles of those materials are all just called “dust.” The rebranding of one, two hundred thousandth of dust we ingest as “microplastic” has made a mountain out of a molehill and made a fortune for people cashing in on the hysteria.
Microplastics Scare Stories
Part of being a good scientist is to present the data in context so that people can accurately assess the situation. Less ethical scientists show only a part of the picture in order to make their findings seem more important. This latter approach brings fame and funding, so it is easy to see why some people are tempted.
Microplastics in blood
We have all been exposed to headline after headline about microplastics, with no mention of other particles. Why is that? We know that plastic is 0.001% of the dust we ingest, so why is no one looking for or reporting on the other 99.999%? Does that sound like good science? I looked and looked for a study that analysed all particles, not just plastic, and finally found one.
This study analysed blood clots from humans and found one particle of polyethylene, which we know to be non-toxic, and a vast array of inorganic pigment particles. Phthalocyanine blue pigment is rated as considerably more toxic than plastics or their common additives with a NOAEL of 200 mg/kg/day (OECD). Why do most studies throw away 99% of particles and only tell you about the plastic ones? Does that seem like good-quality science to you?
“Among twenty-six thrombi, sixteen contained eighty-seven identified particles ranging from 2.1 to 26.0 µm in size. The number of microparticles in each thrombus ranged from one to fifteen with the median reaching five. All the particles found in thrombi were irregularly block-shaped. Totally, twenty- one phthalocyanine particles, one Hostasol-Green particle, and one low-density polyethylene microplastic, which were from synthetic materials, were identified in thrombi. The rest microparticles included iron compounds and metallic oxides.”
D. Wu et al., Pigment microparticles and microplastics found in human thrombi based on Raman spectral evidence, Journal of Advanced Research, 49, pp. 141–150, 2023
It would be good to see more professionalism in the future and less “I found dust” or “I found plastic” while omitting to mention or even look for other particles.
Microplastics cause blood clots myth
“Landmark study links microplastics to serious health problems!” That was the message we received via the mainstream media following the printing of this headline.
“Presence of microplastics in carotid plaques linked to cardiovascular events”
“In patients with carotid artery disease, the presence of microplastics and nanoplastics (MNPs) in the carotid plaque is associated with an increased risk of death or major cardiovascular events compared with patients in whom MNPs were not detected. This finding supports previous observational data that suggest an increased risk of cardiovascular disease in individuals exposed to plastic-related pollution.”
K. Huynh, Presence of microplastics in carotid plaques linked to cardiovascular events, Nature Reviews Cardiology, 21 (5), p. 279, 2024
Based on that, one would have cause for concern. But what does the study really say? When you read the study, the authors specifically say that there’s no evidence that the microplastics caused a problem!
As usual, no one actually took the time to read the story before proceeding to spread panic amongst the public.
“But Brook, other researchers and the authors themselves caution that this study, published in The New England Journal of Medicine on 6 March, does not show that the tiny pieces caused poor health. Other factors that the researchers did not study, such as socio-economic status, could be driving ill health rather than the plastics themselves, they say.”
R. Marfella et al., Microplastics and Nanoplastics in Atheromas and Cardiovascular Events, The New England Journal of Medicine, 390 (10), 2024
Not only that, but a letter to the editor pointed out that the study was not done properly and may not be credible because of the contamination of the samples.
I wondered whether high particle concentrations can cause cardiac events, and the answer is yes, they can.
Y. Du et al., Air particulate matter and cardiovascular disease: the epidemiological, biomedical and clinical evidence, Journal of Thoracic Disease, 8 (1), pp. 8–19, 2016
But if there are 200,000 other inorganic particles per one plastic particle, why on Earth would any sane person assume that the plastic particle is to blame?! The answer is that they wouldn’t because there is no evidence to support that hypothesis.
Such hysterical stories often say this is “linked” to that or “associated” with this, but that is meaningless. Two events occurring together do not mean that one caused the other. If I go for a walk and it’s sunny, do my neighbours assume I made it sunny? I hope not because that would be really silly.
All good scientists know, as Brook pointed out, that correlation does not imply causation.
Eat Ice Cream Get Attacked by Shark
There is a famous cartoon showing that shark attacks and ice cream sales are correlated, and a layperson might be tempted to think that one must cause the other. In fact, they are correlated because both happen when people go to the beach when the weather is nice. There are more shark attacks simply because there are more people in the water when the sun is out. It has nothing to do with eating ice cream. Therefore, we must be wary when we are told that A is “linked” to B. Often, they are linked in some way, but one is not the cause of the other. Scientists remind us that correlation does not mean causation.
Microplastics in the brain
There have been several media headlines about plastic particles moving around the body. I was surprised too. The stories portray this as some new and alarming discovery that is specific to plastic particles. Is that the case? I am not a biologist, so I had to check the science to find out.
I was amazed to learn that particles entering the body and moving is called “translocation” and has been studied for almost 200 years. So, it is not new, and it is not specific to plastics either because they had not been invented in 1844. Quite the contrary, translocation has been reported for all kinds of particles.
E.F.G. Herbst, In: Das Lymphgefasssystem und seine Verrichtungen, (Eds. Vandenhoek and Ruprecht), Gottingen, pp. 333–337, 1844
More recently, various studies have continued to show all kinds of particles in the body are moving around.
“These results demonstrate effective translocation of ultrafine elemental carbon particles to the liver by 1 d after inhalation exposure.”
G. Oberdörster et al., Extrapulmonary translocation of ultrafine carbon particles following whole-body inhalation exposure of rats, Journal of Toxicology & the Environment Health A., 65 (20), pp. 1531–43, 2002
What about the scare stories reporting for the first time that plastic particles can enter the brain? Sounds scary, but instead of reacting to the headline, it is wise to look a little deeper. Is this new information worthy of an immediate response, or is it out of context?
“Micro- and Nanoplastics Breach the Blood–Brain Barrier (BBB): Biomolecular Corona’s Role Revealed”
V. Kopatz et al., Micro- and Nanoplastics Breach the Blood–Brain Barrier (BBB): Biomolecular Corona’s Role Revealed, Nanomaterials, 13, 1404, 2023
In the study, they force-fed mice with an insanely high concentration of lab-made polystyrene particles unlike any particles found in the environment. The unrealistic dose meant that the body’s defence system was overwhelmed, so the particles reached the brain. However, the study tells us nothing about actual exposure conditions and is pretty much meaningless.
For context, we can check historical studies. For example, the following study also detected the movement of particles into the brain.
“There was a significant and persistent increase in added 13C in the olfactory bulb of 0.35 µg/g on day 1, which increased to 0.43 µg/g by day 7. Day 1 13C concentrations of cerebrum and cerebellum were also significantly increased but the increase was inconsistent, significant only on one additional day of the postexposure period, possibly reflecting translocation across the blood–brain barrier in certain brain regions.”
G. Oberdörster et al., Translocation of inhaled ultrafine particles to the brain, Inhalation Toxicology, 16, pp. 437–445, 2004
The Oberdörster group continued to investigate translocation (movement) of particles in the body. They cited a study as far back as 2002, over two decades ago, showing that polystyrene was one such type of nanoparticle among several others, including gold, iridium, and carbon. This shows that the “discovery” of synthetic polystyrene nanoparticles crossing into the brain of rodents is not new at all, but is, in fact, over 20 years old.
G. Oberdörster et al., Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles, Environmental Health Perspectives?, 113 (7), July 2005
The paper on synthetic polystyrene nanoparticles in hamsters was very informative. Nemmar et al. showed that the surface charge of the synthetic polystyrene particles determined their behaviour in the body. This is a key point because laboratory-synthesised polystyrene particles of the type used in the new 2023 study are unlike the kind of polystyrene found in the environment. The lab particles have a charge intentionally added, which makes them interact much more than real uncharged polystyrene particles do. This charge effect has been confirmed by other researchers.
A. Nemmar et al., Ultrafine Particles Affect Experimental Thrombosis in an In Vivo Hamster Model, American Journal of Respiratory and Critical Care Medicine, 66, pp. 998–1004, 2002
S. Wieland et al., Nominally identical microplastic models differ greatly in their particle-cell interactions, Nature Communications, 15 (922), 2024
This reinforces the point that studies on lab-made polystyrene are not relevant for understanding what really happens in the environment. For that matter, scientists have also noted that polystyrene itself is the wrong type of plastic to use because the plastics in the environment are not polystyrene but rather dominated by polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET).
K. Tanaka and H. Takada, Microplastic fragments and microbeads in digestive tracts of planktivorous fish from urban coastal waters, Scientific Reports 6(1):34351, 2016
We can now see that the dramatic headlines about microplastics in the brain were unfounded for multiple reasons.
- The study was invalid due to unrealistically high particle concentrations.
- They used the wrong plastics — a type no one is exposed to in the real world.
- The existence of particles in the body is not news because it has been known for decades.
- The movement of particles around the body, including the brain, is 20-year-old news.
- The same effect happens with all kinds of particles.
Here are some studies spanning many years about other common particles doing the exact same thing that plastics are found to do.
Manganese oxide nanoparticles
“We conclude that the olfactory neuronal pathway is efficient for translocating inhaled Mn oxide as solid UFPs to the central nervous system and that this can result in inflammatory changes. We suggest that despite differences between human and rodent olfactory systems, this pathway is relevant in humans.”
A. Elder et al., Translocation of Inhaled Ultrafine Manganese Oxide Particles to the Central Nervous System, Environmental Health Perspectives, 114 (8), 2006
Carbon black nanoparticles
This one is really pertinent because carbon black makes car tyres black and is abraded into the atmosphere in high amounts.
“Higher levels of black carbon predicted decreased cognitive function across assessments of verbal and nonverbal intelligence and memory constructs.”
S. F. Suglia et al., Association of Black Carbon with Cognition among Children in a Prospective Birth Cohort Study, American Journal of Epidemiology, 167, pp. 280–286, 2008
Zinc oxide nanoparticles
Zinc oxide is used in physical sunscreens, so we are exposed to it.
“Our results suggest that acute exposure to ZnONP induces oxidative stress, microglia activation, and tau protein expression in the brain, leading to neurotoxicity.”
H.C. Chuang et al., Acute Effects of Pulmonary Exposure to Zinc Oxide Nanoparticles on the Brain in vivo, Aerosol and Air Quality Research, 20, pp. 1651–1664, 2020
Iron soot nanoparticles
“Our findings visually demonstrate that inhaled ultrafine iron-soot reached the brain via the olfactory nerves and was associated with indicators of neural inflammation.”
L. E. Hopkins et al., Repeated Iron-Soot Exposure and Nose-to-Brain Transport of Inhaled Ultrafine Particles, Toxicologic Pathology, 46 (1), pp. 75–84, 2018
Titanium dioxide nanoparticles
This is the most common white pigment found in paper, plastics, and physical sunscreens.
“…in the rat, spherical, small TiO2-NPs significantly increased the BBB permeability and entered the brain. TiO2-NPs were accumulated in the brain, but no obvious pathological anomaly was observed in the cerebral cortex and hippocampus.”
X. Liu et al., Size- and shape-dependent effects of titanium dioxide nanoparticles on the permeabilization of the blood-brain barrier, Journal of Materials Chemistry B, 48, 2017
While looking into the science on this topic, I also learned that the ability of nanoparticles to cross into the brain is exploited by scientists — they employ such particles to deliver drugs targeted to the brain. There are quite a few studies on the subject.
While it may be unsettling to think of particles inside our bodies, it is important to note that all particles do it, and our bodies are used to dealing with it. We have developed immune systems that can envelop particles for removal or attack and destroy them.
As we have seen, particulate pollution is a real problem. It is appropriate to study it and evaluate the risks. However, it is not appropriate to obsess over plastics, which are just 0.001% of the particles we ingest.
Nur Hazimah and Mohamed Nor, Lifetime Accumulation of Microplastic in Children and Adults, Environmental Science & Technology, 55 (8), pp. 5084–5096, 2021
It is also not meaningful to scare the public over particles they will never encounter in the real world. Why scare the public with 20-year-old news when we should focus on real and present dangers?
Microplastic in the placenta
This topic is like the case of particles in the blood and in the brain. It is not news and occurs for all kinds of particles, including carbon black pigment found in car tyres.
H. Bové et al., Ambient black carbon particles reach the fetal side of human placenta, Nature Communications, 10, 3866, 2019
The same has been reported long ago for silica (which sand is made of) and titanium dioxide, which is a very common white pigment used in sunscreen.
K. Yamashita et al., Silica and titanium dioxide nanoparticles cause pregnancy complications in mice, Nature Nanotechnology, 6, pp. 321–328, 2011
Silver, silica, carbon, alumina, cerium oxide, diesel exhaust, quantum dots, platinum, titanium dioxide, gold, iron oxide, polystyrene, fullerenes, zinc oxide, zirconium oxide, and carbon nanotubes have all been reported in the placenta.
T. Buerki-Thurnherr et al., Knocking at the door of the unborn child: engineered nanoparticles at the human placental barrier, Swiss Medicinal Weekly, 142, 2012
E. Bongaerts et al., Translocation of (ultra)fine particles and nanoparticles across the placenta; a systematic review on the evidence of in vitro, ex vivo, and in vivo studies, Particle & Fibre Toxicology, 17 (56), 142235, 2020
Dust gets everywhere so that is not so surprising. It is not responsible reporting to act as though this is something new, specific to plastic particles, and dangerous when it is not any of those things.
Toxins & Microplastics
Yet another claim is that microplastics release toxic chemicals, but as we saw earlier in the chapter, plastics and typical additives are non-toxic. So, what do these claims refer to?
One common idea is that fish eat microplastics and are thereby exposed to toxic chemicals. However, closer examination reveals that the chemicals are actually from the ocean water and not the plastic. Such chemicals are absorbed by plastic because “like dissolves like”; this saying refers to the fact that fatty substances (hydrophobic is the scientific term) prefer to be inside the fatty (hydrophobic) polymers, so they leave the sea water in which they are poorly soluble and concentrate inside the plastic instead.
Once more, the NGOs have distorted reality to paint plastics as the villain. NGOs claim that the plastic acts as a “vector” for transporting toxins, but what do studies on toxins and microplastics say? They show that toxic chemicals in the ocean are absorbed by the plastic and are thus removed from the water. The result is that the marine organisms are protected because the poison is now inside the plastic microparticles (MP) and is no longer in the water. That’s the opposite of what the NGOs say.
“Both test species actively ingested the MP particles. However, the presence of MP never increased the bioaccumulation of neither model chemicals, nor their toxicity to the exposed organisms. Bioaccumulation was a linear function of waterborne chemical disregarding the level of MP. Toxicity, assessed by the threshold (EC10) and median (EC50) effect levels, was either independent of the level of MP or even in some instances significantly decreased in the presence of MPs. These consistent results challenge the assumption that MP act as vectors of hydrophobic chemicals to planktonic marine organisms.”
R. Beiras et al., Polyethylene microplastics do not increase bioaccumulation or toxicity of nonylphenol and 4-MBC to marine zooplankton, Science of the Total Environment, 629, pp. 1–9, 2019
This next study came to the same conclusion.
“The addition of microplastics to synthetic water significantly reduced the toxicity of bifenthrin (apparent LC50 = 1.3 µg/L), most likely because sorption of bifenthrin to microplastics reduced its bioavailability to the exposed larvae. A sorption capacity experiment showed that N92% of bifenthrin was sorbed to microplastics.”
The plastic removed 92% of the toxin. The workers made another important point, which is that in the real world, there are so many other types of organic particles around (leaves, sticks, etc.) that the effects of plastic are negligible anyway.
“Strikingly, the addition of microplastics to river water did not mitigate bifenthrin toxicity (apparent LC50 = 1.4 µg/L), most likely due to greater interaction of bifenthrin with organic carbon than with microplastics.”
S. Ziajahromi et al., Effects of polyethylene microplastics on the acute toxicity of a synthetic pyrethroid to midge larvae (Chironomus tepperi) in synthetic and river water, Science of the Total Environment, 671, pp. 971–975, 2019
This highlights how misleading it is to talk about plastic particles while forgetting how insignificant their concentration is in the wider picture.
This next study also found that while plastics absorb toxins and provide a protective effect in the lab, in real-world situations, interaction with natural particles is the major factor.
“Low microplastic concentrations loaded with phenanthrene or anthracene induced a less pronounced response in the sediment communities compared to the same total amount of phenanthrene or anthracene alone.”
“Due to high ambient concentrations of organic pollutants and their sorption to natural particles, the transported amounts of two PAHs (anthracene and phenanthrene) did not add substantial quantities to background environmental levels in the sediment.”
J. Kleinteich et al., Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part II: Polyethylene Particles Decrease the Effect of Polycyclic Aromatic Hydrocarbons on Microorganisms, International Journal of Environmental Research and Public Health, 15 (287), 2018
Probably the most detailed examination of this topic was a review article, which pointed out that all other studies assume that 100% of chemicals would migrate out of microplastic after ingestion; in reality, that does not occur because there is not enough time during digestion. They found that actual exposure levels are vastly lower, so low as to be “small to negligible.”
“Previous risk assessments that evaluate the role of MPs as chemical vectors in humans have so far assumed worst case scenarios in their calculations, with 100% instantaneous leaching of chemicals. In the present study, we performed a probabilistic assessment to evaluate the actual chemical exposure via MPs in relation to dietary and inhalation intake of compounds using the simulated MP intake rates and also accounting for the full variability of the MP continuum. Our methodology also includes quantifying the actual percentage change in the body tissue concentrations with the added chemicals from MP intake. We conclude that the contribution of the MPs to chemical intake is small to negligible for the four representative chemicals investigated in this study…”
Nur Hazimah Mohamed Nor, Lifetime Accumulation of Microplastic in Children and Adults, Environmental Science & Technology, 55 (8), pp. 5084–5096, 2021
An emphasis in this book is zooming out from the plastics-only discussion to get a more balanced viewpoint by comparing plastics with our other material options. Here is a study that compares the chemicals coming out of glass bottles into our drinking water to what happens when we choose PET bottles instead.
“Many more elements leach from glass than from PET bottles. Comparing the same water sold in PET bottles to results for water sold in glass bottles Ce, Pb, Al and Zr are the 4 elements that leach most from glass, but Ti, Th, La, Pr, Fe, Zn, Nd, Sn, Cr, Tb, Er, Gd, Bi, Sm, Y, Lu, Yb, Tm, Nb and Cu are all significantly enriched in the glass bottles when compared to the same water sold in PET bottles.”
C. Reimann et al., Bottled drinking water: Water contamination from bottle materials (glass, hard PET, soft PET), the influence of colour and acidification, Applied Geochemistry, 25, pp. 1030–1046, 2010
In case your chemistry is rusty, they are saying that the metals coming out of glass bottles and contaminating water are far worse than the plastic coming from PET bottles. Metals found are cerium, lead, aluminium, and zirconium, with many other heavy and transition metals leaching from glass as well. When is the last time you read an article in the newspaper or online that mentioned that? Perhaps the glass industry has much better lobbyists to control what we see?
While we are on the topic of perspective, it is worth saying something about the concept of “detection.” We see stories that microplastics were “detected” here or that a toxic chemical was “detected” there. Scientists love to detect things, and the machines they use have grown ever more sensitive. In fact, they are now so sensitive that you could probably detect almost anything you wanted to, almost anywhere. That may sound like an exaggeration, but let me give you an example.
I read a study in which they had detected some kind of chemical coming from microplastics and the concentration was about 1 ng/L (one nanogram per litre). Even as a PhD chemist, I had a hard time visualising how much that really is, so I ran a calculation. Turns out it is such an incredibly low amount that it is almost ridiculous.
A nanogram per litre is one millionth of one part per million. Imagine taking an object, cutting it into a million pieces, taking one of those pieces and cutting it into a million pieces, then selecting just one of those pieces. Concentrations that low are not worth scaring the public over, but that does not stop some scientists and NGOs from doing just that.
All of this chemistry talk may seem bewildering, so I came up with another analogy. The population of the entire planet is around 8 billion people, so what is a millionth of a millionth of that?
A millionth of 8 billion people is 8000 people.
A millionth of that is 0.008 people.
An average person weighs 70 kg.
0.008 of 70 kg is about half of one kilogram (about 1 lb).
A human hand weighs the same amount.
So, starting with the entire population of the world, a millionth of a millionth is the same weight as one human hand.
These are the vanishingly small amounts that we can now detect. Scientists really should be more responsible before proclaiming that they “detected” a substance. We need not just data but a responsible amount of perspective to go with the data.
Bad Science
In The Plastics Paradox book and the website of the same name, I called out the appallingly bad science in the microplastics field. I analysed study after study, finding errors so serious as to instantly invalidate the study. Perhaps people thought I was being too harsh. However, in the years since, other scientists, including Lenz et al., Gouin et al., and Koelmans et al., have made the same observations; they called out the fact that most studies use a kind of special plastic particle that is not even present in the environment then they use a million times too much of it. Some studies even soak the plastic particles in poison so that they can claim that the plastic is poisonous. Two detailed reviews agree with my assessment and find that 85–92% of microplastics studies are flawed for the very reasons I have been stating for years.
What concentration of microplastic should scientists use to create a valid, realistic study? Lenz et al. provided an important contribution on that subject.
“Microplastic research is an emerging field, and there is a lot of misunderstanding and in some cases over-reaction or misinterpretation of results from MP science in the public. We therefore strongly suggest that future studies of MP impact on marine ecosystems should also include concentrations that have been documented in the environment to yield more realistic estimates of sublethal effects.”
“Experimental exposure concentrations tend to be between two to seven orders-of-magnitude higher than environmental levels.”
R. Lenz, K. Enders, and T. G. Nielsen, Microplastic exposure studies should be environmentally realistic, Proceedings of the National Academy of Sciences, 113 (29), E4121–E4122, 2016
They point out that studies use up to ten million times too much plastic compared to the amount that would accurately represent the amount that is really in the environment. Lenz implored other scientists to do proper science at proper concentrations. Any competent toxicologist will tell you that using such high concentrations means that the study is invalid. I would call it junk science, and it is one of the crucial mistakes that invalidates studies on this topic.
Sometimes, the scientists make other errors. One relatively common error is to detect particles and then claim they are microplastics without ever checking to make sure that they are in fact made of plastic. This is science so poor that words almost fail me, and yet, this theme reoccurs. This study claims to have found incredibly high numbers of plastic particles in fruit and vegetables in shops.
“The higher median (IQR) level of MPs in fruit and vegetable samples was 223,000 (52,600–307,750) and 97,800 (72,175–130,500), respectively. In particular, apples were the most contaminated fruit samples, while carrot was the most contaminated vegetable. Conversely, the lower median (IQR) level was observed in lettuce samples 52,050 (26,375–75,425).”
G. O. Conti et al., Micro- and nano-plastics in edible fruit and vegetables. The first diet risks assessment for the general population, Environmental Research, 187, 2020
Such stories go viral, but no one seems to read them to make sure that the science is sound. The scientists should have been suspicious and double-checked their work, but they did not. However, I did. They dissolved the fruit and vegetables in concentrated acid and found particles but did no analysis to show that they were plastic! So, their claim to have found plastic has zero evidentiary support. That is not good science, so I reported the article to the editors and the publisher for investigation.
If those particles were not plastic, then where did they come from? When I was at school, the chemistry teacher put sugar in a glass jar and poured on concentrated acid, which created a foam of carbon. That provides a likely explanation — the scientists created carbon particles when they dissolved the fruit and vegetables in concentrated acid and then incorrectly assumed that they must be made of plastic. Perhaps these scientists should have paid more attention in school.
There are too many examples of this bad science to recount them all, but here is what two reviews found. This first one showed that only around 10% of microplastic studies are done on the right kinds of plastic, namely the PE, PP, PVC, and PET that is present in the environment.
“>80% of studies are identified as not reliable”
“…few studies provide information that support that the particles tested are representative of NMPs found in the environment, or that the concentrations tested are representative of environmentally relevant exposure scenarios.”
T. Gouin et al., Screening and prioritization of nano- and microplastic particle toxicity studies for evaluating human health risks — development and application of a toxicity study assessment tool, Microplastics & Nanoplastics, 2 (2), 2022
A simple analogy might help to highlight why it is so important to do testing on the right kinds of plastic. If you wanted to know whether kittens are dangerous, would you study kittens or lions?
“Microplastics are frequently present in freshwaters and drinking water, and number concentrations spanned ten orders of magnitude (1×102 to 108 #/m3) across individual samples and water types. However, only four out of 50 studies received positive scores for all proposed quality criteria, implying there is a significant need to improve quality assurance of microplastic sampling and analysis in water samples.”
A. A. Koelmans et al., Microplastics in freshwaters and drinking water: Critical review and assessment of data quality, Water Research, 155, pp. 410–422, 2019
They reported that just 8% of studies were reasonable quality and the other 92% were lacking and thus unreliable. As shown in other studies, particles were found in lake, river, ground, tap, and bottled water. As expected, dust is everywhere and the current paranoia around bottled water and microplastic is unwarranted.
We have witnessed accelerating growth in the number of microplastic studies per year. Many would argue that is a good thing. After all, should we not study anything that may present a danger to us? Some argue that more knowledge can only be helpful. Sounds reasonable, doesn’t it?
It does sound reasonable until we look at the cost of all those studies that are paid for with our taxes. Unlimited anything sounds great until the cost is factored in. Plus, what quality is this information that we are paying for?
6400 studies a year on microplastics at around $30,000 per study (an estimate from a professor) means almost $200 million a year of our tax money. That’s a lot.
We just saw that two reviews concluded that around 90% of the studies are flawed / not valid. So, we are wasting around $180 million a year on bad science.
Not only that, but we already have the studies we need to reveal the amount we’re exposed to (extremely low) and the level of threat (non-toxic like clay and cellulose).
“…the experimental design of most studies does not allow distinguishing plastic-specific effects from those caused by any other particles, such as clay and cellulose, which are ubiquitously present in the environment. We suggest that microplastic effects reported in recent ecotoxicological studies are similar to those induced by the natural particles.”
M. Ogonowskia, Z. Gerdesa & E. Gorokhova, What we know and what we think we know about microplastic effects — A critical perspective, Current Opinion in Environmental Science & Health, 1, pp. 41–46, 2018
Studies conclude plastics like PE, PP, PVC, and PET are not toxic — no matter whether they are particles or fibres.
“This work for the first time investigated and compared the intestinal uptake and cytotoxicity of microplastic particles of the commonly produced materials PE, PP, PVC and PET in vitro.”
“None of the particles triggered acute toxic effects, regardless of their shape and material.”
“Only excessively high concentrations far beyond realistic dietary exposure of consumers induce cytotoxic effects.”
V. Stock et al., Uptake and cellular effects of PE, PP, PET and PVC microplastic particles, Toxicology in Vitro, 70, 105021, 2021
“The results revealed no adverse effects of secondary microplastics (PP and PS) as determined by clinical signs, body weights, or organ weights and no gross pathological findings in any of the treatment groups. This study will provide basic data for sub-chronic and chronic repeated dose toxicity of microplastics.”
J. Sik-Kim, Acute toxicity evaluation of polypropylene and polystyrene microplastics in Sprague Dawley (SD) rats after oral administration, Journal of Pharmacological and Toxicological Methods, 105, 106813, 2020
How about we stop wasting money on bad science done on a topic that’s already been covered? I know some people will reply that science never stops, and we might discover some new threat, but that argument does not hold water. If plastic dust was especially toxic, the last 50 years of studies would have already said so, but they didn’t. Repeating the same studies makes as much sense as paying someone to drop an apple all day every day just to check that Isaac Newton was correct and that gravity exists.
Microplastic Degradation
The general perception is that plastics never really degrade — instead, they fragment into smaller and smaller pieces and then stop. This, of course, completely defies logic and our own experience with other materials. Do leaves crumble into pieces and then stop degrading at a certain size? Do cars start rusting and then magically stop? No, they don’t, and you would be called a fool if you declared they did, and yet, that is precisely what NGOs claim about plastics.
Scientists have shown that microplastics continue to degrade until they form water and carbon dioxide, which is what all other organic materials do, meaning they degrade to the same final products as paper, apples, leaves, and trees. All organic matter (PE, PP, PET, apples, leaves, cotton) is based on the same elements, including carbon, hydrogen, and oxygen. This common chemistry is what makes them degrade similarly.
“Microplastic debris in the environment degrades mechanically, chemically, and biologically.”
“Microplastics degrade through the same processes that break down macro-plastic debris items, albeit more quickly because of their higher surface to volume ratio.”
“Carbon dioxide, H2O, and CH4 are produced in this final step known as mineralization.”
J.C. Prata in T. Rocha-Santos, M. Costa, C. Mouneyrac (eds), Handbook of Microplastics in the Environment, Springer Switzerland, pp. 531–542, 2022
A. Delre et al., Plastic photodegradation under simulated marine conditions, Marine Pollution Bulletin, 187, 2023
What about microplastics in the ocean? Do they degrade too? This study looked at the most common plastics, including LLDPE, PP, EPS (polystyrene foam), PET, PVC, PA, and PCL.
“Using real world data, we reveal that plastic surfaces can degrade at a rate of up to 469.73 µm per year, 12 times greater than previous estimates.”
C. Maddison et al., An advanced analytical approach to assess the long-term degradation of microplastics in the marine environment, Materials Degradation, 7 (59), 2023
Not only do plastics degrade in the oceans, but they do so over 10 times more rapidly than originally assumed. Rather than endlessly accumulating, as is claimed, amounts found are low, and they are removed by degradation, just the same as other materials.
The Missing Factor
There is one aspect in the discussion around microplastics that I have never seen mentioned. Imagine that plastic was replaced because of concerns over microplastics — would that be a positive move? Well, we know it takes 3–4 times more paper, metal, wood or glass to replace plastic and that those materials also degrade to form particles. In the case of wood, those particles are known to cause cancer. Copper dust is highly toxic too. So, replacing plastic would increase the quantities of particles we are exposed to, and the average toxicity of those particles. Does that sound wise? People are so eager to be against plastic that they almost never stop to consider the consequences of moving to alternatives.
Summary
Fear is not rational, and it is not easy to convince someone not to be frightened. We have thousands of phobias, from arachnophobia (fear of spiders) to xenophobia (fear of foreigners). We can add plastiphobia to that list. People have been intentionally misled into fearing plastics when decades of science show that there is no rational reason for that fear. Hopefully, those of you who have read this far have been reassured by the huge amounts of peer-reviewed evidence. This is not some new, previously unidentified problem. On the contrary, we have 50 years of studies on plastic particles — amounts are low, and they are non-toxic. We are only concerned because NGOs cleverly rebranded plastic dust to make it sound scary and were helped by the media, who abandoned the truth long ago.
One crucial factor when evaluating risk is perspective. If we cannot prioritise large, genuine threats over insignificant or imaginary ones, then we will end up paralysed, hiding under a blanket and afraid to venture outside lest the sky fall on our heads. In the name of perspective, here is a breakdown of what people really die from. It is not plastic, microplastic, or parts per million of chemicals. Anyone who truly desires a safer, healthier life can glance at this list to see what needs to be done.
People are terrible at accurately gauging risk, which is why numbers help us to focus on what matters. In 2019, over 60,000 people died from snakebites, which equates to around 3 million years of life lost, whereas recorded mortalities from microplastics were zero. This example emphasises the importance of real risk over imaginary risk.
N. L. S. Roberts et al., Global mortality of snakebite envenoming between 1990 and 2019, Nature Communications, 13, 6160, 2022
Just recently, someone said that they hope I am not offended that they keep asking questions about microplastics after I had provided several links to the science. He clearly had not looked because his questions were already addressed in the links provided. My reply was:
“I am not at all offended. Anyone concerned can look at the science provided, see the facts and be reassured. Or they can avoid looking and continue to be worried needlessly. It’s up to each person to decide.”
We need to recognise that there are many types of people. Some cannot be reached with facts, and others enjoy being scared for no reason. These are the people who pay money to see horror movies and be scared senseless. Each to their own.
Sensible actions to improve one’s health would be to go easy on the pizza, take a walk every day, don’t smoke, and don’t drink too much. These simple, easy steps will have far more benefit than anything else. Of course, fretting over trivial things like straws or plastic dust is less work than addressing real issues.
When it comes to policy, there is no evidence to suggest that any policy changes are needed. However, there certainly is an urgent need for other kinds of action.
We need to expose and shut down NGOs that frighten us and our children with lies.
We should impose heavy fines on journalists and media outlets that mislead us.
We should impose heavy fines on academics who conduct junk science experiments with a million times too much plastic.
Let’s create a better future based on truth and wisdom instead.
~90% of the science on microplastics is worthless, and the studies relayed to us are only the scary ones because that’s how the media and NGOs make money. When we really read the studies and find the reliable ones with proper scientific methods, we see 50 years of data and no credible evidence of harm. The FDA agrees.