More than a month has passed since the devastating MV X-Press Pearl incident, where a cargo ship carrying chemicals caught fire off the coast of Sri Lanka. Tonnes of nurdles spilled into Sri Lankan territorial waters due to the disaster and are still being washed ashore. Nurdles are a form of primary microplastics that can create havoc on our biological systems if left uncleared. In this light, we spoke to an avid educator on the harmful effects of microplastics, University of Sri Jayewardenepura Faculty of Medical Sciences Department of Anatomy Lecturer Dr. Sajith Edirisinghe and The Pearl Protectors, a youth-led marine conservation organisation committed to reducing plastic pollution and conserving the marine environment in Sri Lanka.
What are the unseen effects of microplastics on human health?
Research carried out on animal models have shown that when sea animals ingest polystyrene microplastics (MPs) with diameters of 5 and 20 μm, its presence was evident in their organs such as the liver, kidney, and gut within just 28 days. The increased levels of inflammation directly contributed to the changes caused to the organs. They have detected increased lipid droplets in liver tissue, which predicts that MPs can cause lipid metabolism disorders and liver inflammation. Another research has shown that mice exposed to polystyrene MPs have reduced intestinal mucus secretions which has contributed to a change in their gut flora. In the nervous system, it was observed that there were changes in locomotor activity. Based on the results obtained from mammalian animal models, it is rational to assume that plastic particles can accumulate and affect human health, stated Dr. Edirisinghe.
The impact of the current disaster
The recent spillover of nurdles, which is the primary raw material for most plastic goods we consume, are small and easily transportable. Like other plastics, these can be mistaken for food by marine animals as they resemble fish eggs. Hence, ingestion of these tiny particles itself could have deadly consequences to marine life. When they enter our marine environment it causes a myriad of hazards and becomes toxic. Because these nurdles accumulate pollutants once ingested, they can leach out and cause toxicity. Therefore, clearing these microplastics from our beaches requires expeditious efforts.
Overall burden of microplastics
There are already 51 trillion microplastics that are littering our oceans. According to some researchers, the average abundance of micro or nano plastics (MNPs) in drinking water is 193 particles per litre, which is much lower than the concentration used in the animal studies above. However, based on the fact that people drink two to three litres of water per day, it may be important to consider the effects of long-term exposure to MNPs, stated Dr. Edirisinghe. Additionally, MNPs have also been detected in air, table salt, honey, and sugar, indicating other sources of MNP exposure to humans. However, there is no accurate data to determine the daily exposure and intake of MNPs. The analysis “No Plastic in Nature: Assessing Plastic Ingestion from Nature to People” prepared by Dalberg, based on a study commissioned by the World Wildlife Fund (WWF) and carried out by the University of Newcastle, Australia, suggests people are consuming about 2,000 tiny pieces of plastic every week. That’s approximately 21 grams a month, just over 250 grams a year. Several studies measuring microplastics in potable water reported concentrations of up to 35,436 particles per litre in bottled mineral water.
Current studies suggest that hazardous chemicals can be adsorbed onto MNPs, and these adsorbed pollutants on MNPs could be much higher in concentration than those detected in the surrounding environment. Moreover, new studies support the possibility that the adsorbed chemicals exhibit more toxicity than pure chemicals alone. Hydrophobic organic chemicals (HOCs) exist in the environment in many varieties and many of them are known to be endocrine-disrupting chemicals (EDCs), such as the polychlorinated biphenyls (PCBs), perfluorinated chemicals (PFCs), bisphenol-A (BPA), and phthalates. HOCs have been shown to adsorb onto MPs.
When considering heavy metals, MPs can absorb metals from both aquatic and sedimentary environments, allowing for an accumulation of these metals along the food chains. Another study conducted over 12 months by Rochman et al. demonstrated an increased pattern of many heavy metals accumulating on MPs, including cadmium, nickel, zinc, and lead. This suggests that the longer MPs stay in the environment, the more heavy metals they can accumulate. Thus, a mixture of metals, including those listed as priority pollutants by the US Environmental Protection Agency (EPA), can be found on this plastic debris. Heavy metals are a potential hazard to both wildlife animals and humans. For example, mercury has been observed to bioaccumulate alongside MPs in a variety of different species of marine fish, and mercury was detected in the brain and muscle tissues of those animals.
This research shows there is a possibility that the body can uptake not only the MPs but also the adsorbed toxic chemicals that MPs carry. There is also the possibility that a combination of MPs and their adsorbed chemicals can be more toxic than these chemicals on their own. This was proven by a study that examined the exposure to both MPs and organophosphorus flame retardants (OPFRs), which are a type of HOCs. The results demonstrated that the co-exposure of these particles induced greater oxidative stress, neurotoxicity, and metabolic disruption in mice than both the MPs or OPFRs alone. The researchers predict that these effects could be due to an increase in uptake of the toxic chemicals in the presence of MPs.
Because of this, it makes MPs even more complex to understand because examining pure plastics in the lab and their impact does not address how plastics absorb chemicals. Another laboratory-based study has also shown that MPs and natural acidic organic polymers (NAOP) such as fulvic acid and humic acid when jointly exposed to zebrafish (Danio rerio), significantly affected oxidative stress and enzymatic antioxidant defence mechanisms of zebrafish. The temperature of the environment, mode of transport, and type and size of accumulated plastics can potentially affect which chemicals they adsorb, to what degree, and how they will encounter humans or aquatic life.
Another critical issue to be considered is the leaching of original plastic additives, such as BPA, phthalates, OFPRs, etc., which have been demonstrated to exhibit endocrine-disrupting effects and other toxicities. The release of plastic additives may take place during the usage of the plastics or after their disposal. An additive’s passage potential to the human body depends on the polymer’s pore diameter, the size of the additive, and many other factors. For example, the additives of a lower molecular weight move more easily through a polymer with a bigger pore size. Also, the surrounding environment of the plastics can affect the chemical properties of polymers and their additives. For example, increasing temperatures can help the movement of additives in polymers, and exposure to UV radiation can increase the rate of plastic degradation.
The plastics that are exposed to the different concentrations of saltwater in the ocean can desorb estrogenic plasticisers. The water that passes through plastics used for landfills releases various acidities and chemicals into the water. Due to these releases, different biological populations also have the potential to degrade or transform into additives. For example, bacterial populations can colonise and modify.
Therefore, the uncontrolled release of plastics into the environment causes more harmful effects than we are already aware of. Still, we see only the tip of the iceberg. More studies are needed for a better understanding of this “unseen effect of the unseen particle”, stated Dr. Edirisinghe.
Current efforts to clear nurdles
The Pearl Protectors are currently carrying out an islandwide initiative to clear nurdles. It’s carried out in the following phases.
| Phase | Location description |
| Phase 1 | Pilot initiation at Wellawatta and Mt. Lavinia shorelines |
| Phase 2 | Wellawatta, Mt. Lavinia, Dehiwala, Galle Face, Ratmalana, Lunawa, Dehiwala Canal, Modara, Angulana, Crow Island, and/or donate some of the apparatus packages to the armed forces in cleaning efforts |
| Phase 3 | Wellawatta, Mt. Lavinia, Dehiwala, Galle Face, Ratmalana, Lunawa, Dehiwala Canal, Modara, Angulana, Crow Island, Preethipura, Dikkowita, Uswetakeiyawa, Moratuwella, Panadura, Wadduwa, Pothupitiya, Kalutara, Katukurunda, Beruwala, Moragalla, and/or donate some of the apparatus packages to the armed forces in cleaning efforts |