Plastic is entering human bodies when we consume water and seafood. Marine plastic pollution must be tackled, beach cleanups being one way. | Pic by SL Wong

Plastics in the Body A Worrying Trend

Microplastics are now found in more parts of the human body, writes Professor Dr Lee Yeong Yeh, whose team confirmed the presence of plastics in Malaysians’ bowels. What does this mean?

THIS YEAR, scientists found plastic in the human placenta. This discovery highlights the extent to which plastic permeates our bodies. It should make us very concerned.

By now, it is quite common knowledge that microplastics – smaller than a papaya seed – are ubiquitous in the human food chain, especially seafood and drinking water. This has been shown in many studies, including those in Malaysia.

(Photo: Plastic is entering human bodies when we consume water and seafood. Marine plastic pollution must be tackled, beach cleanups being one way. | Pic by SL Wong)

On average, Malaysians may be ingesting 5 g of microplastics every week (approximate to the weight of a credit card). This must have us wondering what could be happening to the microplastics that we ingest.

Microplastics, broadly defined as particles below 5mm in size, are polymers whose composition may include polycarbonate, polypropylene, polyamide, polyvinyl chloride and polyethylene.

These synthetic polymers are largely derived from organic fossil fuels, and by nature, are hardly digestible, unlike natural polymers.

Once in then what?

After humans ingest these microplastics, would the microplastics appear in our poo? Yes, they  would.

The first human study that detected microplastics in stools was reported in the journal, ‘Annals of Internal Medicine’, in 2019, where all the 8 healthy volunteers were tested positive for microplastics.

If microplastics appear in stools, would they be found in the bowels? Yes they would.

Last year, a group of Malaysian investigators (myself included) detected microplastics in the large bowels of all 11 study participants (9 with colon cancer and 2 normal colons).

READ: Lee Yeong Yeh presented preliminary results of the Malaysian research two years ago, which Macaranga covered. Read how this is part of a bigger plastics research project.

Now, if microplastics appear in the bowels, would they be found elsewhere in the human body? Once again, yes, they would.

This year, the first evidence of microplastics in human placenta was reported in 6 participants. This means that plastics could travel beyond the bowels into other parts of the body and potentially affect health.

The science of detecting

How do you detect microplastics in the body? It can be a lengthy process in the labs but in a nutshell, the samples from the body need to be digested first using a chemical agent, diluted with water, then the plastics are filtered through a thin membrane paper before being dried.

The microplastics can then be observed and counted using microscopes.

For example, in our study of Malaysians, we detected an average of 300 microplastics per bowel sample.

While the microplastics came in many colours, the most common were transparent, and of the many shapes, the filament was the most common (Figure 1). The implications of these observations are unclear at the moment.

We then characterise the types of polymer using spectroscopy equipment – similar to those used for x-rays – including the micro-Fourier Transform InfraRed (FTIR) and Raman.

In our study, the most common polymers found in bowels include polycarbonate, polyamide and polypropylene, but their impacts are still not entirely known.

It’s not looking good

And so you may ask, what could be the adverse health effects from these microplastics?

First, plastics can leach hormone-like substances, for eg bisphenol A or BPA which may cause metabolic disorders or potentially cancer.

This is because microplastics could absorb and bind harmful additives or chemicals, which may increase the risks of obesity; cause some form of cancer, for example breast cancer; and may be responsible for low sperm counts in males and early puberty in females.

Second, microplastics may accumulate at the tissue level, and result in pathology including inflammation. Moreover, the microplastics may translocate through the blood or lymph and deposit in other organs, including the heart and lungs.

Third, the plastics may induce changes in gut bacteria and interfere with our immune system, causing infection. However, all the above potential adverse effects need more confirmatory clinical studies.

There must be something

At this juncture, the most pressing question is what can we do?

As the United Nations Environment Programme (UNEP) pointed out, “plastics are the largest, most harmful and most persistent component of marine litter”.

Malaysia alone produces 900,000 tons of plastic waste; almost half ends up in Malaysian waters – and therefore seafood which we consume.

Most concerning is the sharp growth of plastic waste, expected to triple by 2040, and the potential impacts to the climate, wildlife and also human health.

All hands on deck

From the very start of this commentary, it is clear that reducing plastic waste is vital. Everyone plays a role in this regard.

At the climate change summit in Glasgow (COP26), addressing plastic pollution was among the concerns of the meeting. On the global front, governments are looking at cooperating to do this within the broader purview of tackling climate change.

Medical organisation the World Gastroenterology Organisation has set up a climate change working group to provide ‘green’ directions and activities for its members.

This is a laudable initiative which should be emulated by other medical societies and non-governmental organisations.

Plastic roadmap

On the national front, Malaysia has drawn up a regulatory roadmap to zero single-use plastic from 2018 to 2030. On the personal level, we can play our part by reducing plastic use and waste.

Our study that found microplastics in the bowels was done on Malaysians living on the east coast of Peninsular Malaysia ie coastal dwellers who are the highest consumers of seafood. But any Malaysian can be similarly affected.

To conclude, plastic pollution of the environment is a global crisis. Though it requires further research, there are indications that there may be potential adverse health effects from our exposure to and ingestion of microplastics.

Everyone plays a role to curb plastic pollution and turn the tide on climate change.


[Edited by SL Wong]

Professor Dr Lee Yeong Yeh is a medical doctor and Consultant of Gastroenterology, Hepatology and Internal Medicine, School of Medical Sciences, Universiti Sains Malaysia.



[1]      Ma ZF, Ibrahim YS, Lee YY. Microplastic Pollution and Health and Relevance to the Malaysia’s Roadmap to Zero Single-Use Plastics 2018–2030. Malaysian J Med Sci 2020;27:1–6.

[2]      Schwabl P, Koppel S, Konigshofer P, Bucsics T, Trauner M, Reiberger T, et al. Detection of various microplastics in human stool: A prospective case series. Ann Intern Med 2019;171:453–7.

[3]      Ibrahim YS, Tuan Anuar S, Azmi AA, Wan Mohd Khalik WMA, Lehata S, Hamzah SR, et al. Detection of microplastics in human colectomy specimens. JGH Open 2020:Early View.

[4]      Ragusa A, Svelato A, Santacroce C, Catalano P, Notarstefano V, Carnevali O, et al. Plasticenta: First evidence of microplastics in human placenta. Environ Int 2021;146:106274.

[5]      UNEP. From pollution to solution. Nairobi: 2021.

[6]      Leddin D, Omary MB, Veitch A, Metz G, Amrani N, Aabakken L, et al. Uniting the global gastroenterology community to meet the challenge of climate change and non- ­ recyclable waste. Gut 2021;70:2025–9.


The views expressed here are those of the author/contributor and do not necessarily represent the views of Macaranga.

MORE PLASTICS STORIES: Plastic Solutions: It’s Complicated | When Plastic Hits You in the Gut


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