Plastic’s Fantastic – Unwrapping the World’s Largest Unregulated Clinical Trial

By now we are aware that tiny plastic particles are all around us and, as humans, can’t help but ingest them. It’s the same in the animal kingdom and for the humble honey bee. Science writer Dave Black examines what that means for their health, and ours, and the food we both consume.

By Dave Black

Transmission of microplastics from the environment to honey bees and hive materials. Source: Gilani et al. 2025.

At the turn of this century Paul Crutzen, a Dutch atmospheric chemist, wrote a couple of essays introducing the idea of the ‘Anthropocene’ epoch to most of us[i]. It was a daring but controversial idea, not least (for me) because of the sense of ‘mansplaining’ to geologists what an epoch was —my father was a geologist. It’s now quite common to hear people in science and media talk about the ‘Anthropocene’, by which they mean, the Time Of Man, the human ‘epoch’.

Epochs are not defined by biology, or oceanography, or atmospheric science, interesting though they may be. Nor by human hubris. For Geology an epoch is precisely defined as a period of time characterised by the geological records made of rock strata and sediments, the physics, chemistry, and processes of the solid parts of the earth. There is even a committee (The International Union of Geological Sciences) that considers these things. Understandably, the geoscientists rejected the idea, at least for now, and continue to describe the geological epoch we are in as the Holocene.

A Sense of Scale

In describing the 4.5 billion years (4,540 million years) of Earth’s history a few hundreds of thousands, or millions, of years that occupy an epoch are loose change, there are 37 epochs. The first insects appear around 320 million years ago, 20 epochs ago. Almost all of human history falls within one epoch; modern humans (Homo sapiens) are only 300 thousand years old. If we were to decide, without the benefit of knowing what may happen in, say, the next 300 thousand years, that the last 75 years of human history was so significant that it marked a new and distinct geological epoch what markers in the geophysical record should we choose? In 500 million years’ time what fossil could indelibly and permanently mark a global transition from ‘Man, a natural ape, to ‘Man’ the super-natural power?

There are a few such ‘timestamps’ being debated, some more likely to produce a clean geological ‘signal’ than others, none of them a legacy we could be proud of. They include the significant increase in sedimentation and erosion, an altered carbon cycle evident in ice cores and sea acidification, and radionuclide ‘fallout’ of uranium and plutonium suddenly carpeting the globe from the 1950s. There are also materials and compounds being produced now that have never – will never – originate from natural causes, half the concrete ever made, the most abundant material in human history, has been produced in the last 20 years[ii].

Possibly the most significant of these new materials is plastic. The rapid growth in the production of plastics that has taken place since WWII has only been outdone by concrete and steel, which has been in production for considerably longer. In 2017 a group of researchers attempted to quantify the manufacture and fate of all the plastic that has ever been made, which came to 8.3 billion tonnes by 2015, of which 79% has already accumulated either in land fill or ‘loose’ in the environment[iii]. Less than 10% was recycled. The cumulative amount produced is already more than enough to have wrapped the Earth in a layer of cling-film[iv], and by 2050 there’ll be enough for six layers of cling-film[v]. This isn’t the Anthropocene or the Holocene, it’s the Plasticene.

Frayed and Aged

The reality of our plastic is not a suffocating sheet though. Unmanaged plastic in the environment mostly exists as small fragments, fibres, and granules that result from the photochemical and physical degradation of larger plastic objects and materials that are disposed of incorrectly; from cosmetic products where they used as exfoliants; and from the wear of synthetic textiles subject to the abrasive action of washers and dryers. These particles, between one nanometre and five millimetres long, are commonly what’s known as ‘microplastics’. They are very mobile, last an eternity, and have been found everywhere scientists have looked[vi]. That’s the plastic problem, the sheer scale of an unprecedented, profound, global change.

The routes of exposure in apiculture practice to microplastics. Source: Gilani et al. 2025.

Honey bees have been used as environmental samplers for a long time, routinely testing for pollutants, pesticides, even explosives. As expected, they are the perfect dust-wand. A recent Danish study (2020) showed microplastics on the bodies of bees from all 19 urban, suburban, and rural apiaries in the study. Data in the scientific literature from China, France and Germany indicate a rate of microplastic precipitation from the atmosphere in the order of tens to hundreds of microplastic particles per square meter every day[vii], there to be collected by bees. A German paper in 2015[viii] considered 47 honeys from supermarkets and from small-scale local beekeepers and the flowers from 22 flowering plants in the region and concluded, “These data suggest that the global environment is affected to a large extent by microplastic particles either from direct inputs or from fragmentation of macrolitter.” Microplastic fibres are taken up by adult worker bees in their cuticle and digestive tract, and are transferred to larvae, honey, and wax. However, it’s completely unclear whether that matters.

Knowing What We Don’t Know

It surely follows that as all the air and water contains micro- and nano- particles of plastic so do bees, so does our food, and so do we. So far, in a significant review paper[ix], microplastic contamination has been pointed out in honey, salt, sugar, beer, tap and bottled water, canned sardines, sprats, and fresh seafood, from hundreds of locations in countries all around the world. There is obviously some interest in finding out if the particles are harmful. At the moment almost every study so far is merely ‘exploratory’, and different, so there are no standardised methods or agreed definitions, which means no assessments of exposure or risks make any sense at all.

The size of the particles vary, the type of polymers the plastic is made of can be one of dozens, and there may be special additives or they could be contaminated with chemicals or microbes. The physical size of the particles can determine where microplastics end up. In the case of bees, if they are big enough they can be removed by the proventriculus. Smaller particles should be contained by the peritrophic membrane in the gut and eliminated from the body. Only the tiniest particles might be relevant in terms of systemic exposure or tissue damage to the bee. ‘Nanoplastics’ are therefore likely to be more hazardous, but that is not to say they are.

Early Indications

The few peer-reviewed studies to date that specifically relate to honey bee health suggest we might want to give the matter some thought[x]. Al Naggar et al. (2021)[xi] conducted a study where they exposed honey bees to small (27 ± 17 μm) and large (93± 25 μm) polystyrene microplastic fragments over 14 days. Survival of the bees was unaffected, but body weight reduced.

The possible health effects of microplastics on honey bees. Source: Gilani et al. 2025.

Ferrante et al. (2024)[xii] examined the oral toxicity of polystyrene (4.8–5.8 μm) and polymethyl methacrylate (1–40 μm) microspheres, separately and in combination, observing their effects on the immune system and the survival of the workers. The found the spheres worsened the survival and immune response of the bees, and led to changes in their cuticular profiles. (Bees would not normally encounter spheres, their greatest exposure is to air or water borne textile fibres and fragments.)

Part of the Ferrante team, Pasquini et al. (2024)[xiii] analyzed the effects of oral exposure to spherical particulate microplastics on cognitive capacity and examined accumulation in the brain. Fluorescent microspheres (1–5 μm) were used to determine whether microspheres of this diameter can penetrate the blood–brain barrier of bees. All treatments impaired learning capacity and memory, with polystyrene causing the most severe effects. The imaging analysis revealed that microplastics measuring 1 to 5 μm penetrated and accumulated in the brain after just three days of oral exposure, predominantly in the optic lobes.

Wang et al. (2022)[xiv] sought to assess the possible influences of polystyrene particles of different sizes (micro and nano-plastic) using microplastics with a diameter of 100 nm, 1 μm, and 10 μm, as well as fluorescent-labeled polystyrene microplastics (10 μm) traced in the bee gut. Particles with a diameter of 100 nm significantly decreased body weight and survival rate, induced abnormal growth of the intestinal cells and decreased the relative abundance of Lactobacillus and Bifidobacterium. The treated honeybees became more susceptible to the pathogenic Hafnia alvei, leading to a mortality rate five-times the controls.

‘Fortune Favours the Brave’

The warning signs might be there, but it’s not yet enough evidence to reasonably evaluate whether microplastics are really hazardous to bees (or humans), and, if they are, we can’t say whether they are more or less hazardous than all the other hazardous things they deal with. If microplastics — nano-plastics — are harmful for honey bees, what practical steps could limit exposure?

And what about us? At what point do we worry about consumer safety, real or perceived; business risk or human health? In one attempt this year to quantify the human consumption of microplastics from the available data, such as it is, a French study looked at the very tiny particles we inhale (<10 µm, a similar scale to diesel particulate matter in exhausts) and has estimated that in cars and indoor spaces, we breathe in 68,000 bits of plastic every day[xv]. In another, the Canadian authors concluded that, from all sources (consumed and inhaled), an average American adult man ingested 114,000 particles of plastic annually[xvi]. Of that, the honey consumed was estimated to contain 70 fragments. Do those 70 fragments matter?

Welcome to the world’s largest unregulated clinical trial.

Dave Black is a commercial-beekeeper-turned-hobbyist, now retired. He is a regular science writer providing commentary on “what the books don't tell you”, via his Substack Beyond Bee Books, to which you can subscribe here.

References

[i]P. J. Crutzen and E. F. Stoermer. 2000. “The ‘Anthropocene.’” IGBP Newsletter 41 (May): 17–18. Available in 'The Future of Nature, Documents of Global Change', edited by Libby Robin, Sverker Sörlin and Paul Warde. Yale University Press, and:- Crutzen, P. Geology of mankind,. Nature Vol 415, 23 (2002), https://doi.org/10.1038/415023a

[ii]Concrete Built The Modern World. Now It’s Destroying It. Joe Zadeh December 6, 2022, Noema Magazine, Berggruen Institute, https://www.noemamag.com/concrete-built-the-modern-world-now-its-destroying-it/

[iii]Geyer, R., Jambeck, J.R., Law, K.L., 2017. Production, use, and fate of all plastics ever made. Sci. Adv. 3, e1700782. https://doi.org/10.1126/sciadv.1700782

[iv] Plastic wrap, Saran wrap, cling wrap, Glad wrap, food wrap, etc.

[v]Zalasiewicz, J., Waters, C.N., Ivar Do Sul, J.A., Corcoran, P.L., Barnosky, A.D., Cearreta, A., Edgeworth, M., Gałuszka, A., Jeandel, C., Leinfelder, R., McNeill, J.R., Steffen, W., Summerhayes, C., Wagreich, M., Williams, M., Wolfe, A.P., Yonan, Y., 2016. The geological cycle of plastics and their use as a stratigraphic indicator of the Anthropocene. Anthropocene 13, 4–17. https://doi.org/10.1016/j.ancene.2016.01.002

[vi]Barnes, D.K.A., Galgani, F., Thompson, R.C., Barlaz, M., 2009. Accumulation and fragmentation of plastic debris in global environments. Phil. Trans. R. Soc. B 364, 1985–1998. https://doi.org/10.1098/rstb.2008.0205

[vii]Edo, C., Fernández-Alba, A.R., Vejsnæs, F., Van Der Steen, J.J.M., Fernández-Piñas, F., Rosal, R., 2021. Honeybees as active samplers for microplastics. Science of The Total Environment 767, 144481. https://doi.org/10.1016/j.scitotenv.2020.144481

[viii]Liebezeit, G., Liebezeit, E., 2015. Origin of Synthetic Particles in Honeys. Pol. J. Food Nutr. Sci. 65, 143–147. https://doi.org/10.1515/pjfns-2015-0025

[ix]Newfoundland and Labrador) and two protected beaches along ’ Nova Scotia s Eastern Shore, on the Atlantic c

[x]Shavali Gilani, P., Moradian, M., Tajdar‐oranj, B., Basaran, B., Peivasteh‐roudsari, L., Javanmardi, F., Khodaei, S.M., Mirza Alizadeh, A., 2025. Microplastics comprehensive review: Impact on honey bee, occurrence in honey and health risk evaluation. Journal of Applied Ecology 1365-2664.70030. https://doi.org/10.1111/1365-2664.70030

[xi]Al Naggar, Y., Brinkmann, M., Sayes, C.M., AL-Kahtani, S.N., Dar, S.A., El-Seedi, H.R., Grünewald, B., Giesy, J.P., 2021. Are Honey Bees at Risk from Microplastics? Toxics 9, 109. https://doi.org/10.3390/toxics9050109

[xii]Ferrante, F., Pasquini, E., Cappa, F., Bellocchio, L., Baracchi, D., 2024. Unravelling the microplastic menace: Different polymers additively increase bee vulnerability. Environmental Pollution 352, 124087. https://doi.org/10.1016/j.envpol.2024.124087

[xiii]Pasquini, E., Ferrante, F., Passaponti, L., Pavone, F.S., Costantini, I., Baracchi, D., 2024. Microplastics reach the brain and interfere with honey bee cognition. Science of The Total Environment 912, 169362. https://doi.org/10.1016/j.scitotenv.2023.169362

[xiv]Wang, K., Zhu, L., Rao, L., Zhao, L., Wang, Y., Wu, X., Zheng, H., Liao, X., 2022. Nano- and micro-polystyrene plastics disturb gut microbiota and intestinal immune system in honeybee. Science of The Total Environment 842, 156819. https://doi.org/10.1016/j.scitotenv.2022.156819

[xv]Yakovenko, N., Pérez-Serrano, L., Segur, T., Hagelskjaer, O., Margenat, H., Le Roux, G., Sonke, J.E., 2025. Human exposure to PM10 microplastics in indoor air. PLoS One 20, e0328011. https://doi.org/10.1371/journal.pone.0328011

[xvi]Cox, K.D., Covernton, G.A., Davies, H.L., Dower, J.F., Juanes, F., Dudas, S.E., 2019. Human Consumption of Microplastics. Environ. Sci. Technol. 53, 7068–7074. https://doi.org/10.1021/acs.est.9b01517