SINGAPORE: Plastic nanoparticles - plastic pieces smaller than 1 micrometre - have been found to accumulate in certain marine organisms and could be transferred up the food chain, according to a study by scientists from the National University of Singapore (NUS).
It is estimated that there are more than 150 million tonnes of plastic in the world's oceans, with 8 million tonnes ending up there every year.
This plastic can get broken down into smaller pieces and eaten by marine animals that mistake them for food.
The NUS research team looked at smaller pieces of plastic - nanoplastics - using barnacles and their larvae to understand how nanoplastics could impact marine organisms.
As barnacle larvae are transparent until they mature, feeding them with fluorescent, non-toxic nanoplastics meant the researchers could easily spot these under the microscope.
"Their short life cycle and transparent bodies made it easy to track and visualise the movement of nanoplastics in their bodies within a short span of time," said Mr Samarth Bhargava, a Chemistry PhD student who contributed to the research paper.
The team demonstrated for the first time that nanoplastics consumed during the larval stage are retained and accumulated inside the barnacle larvae until they reach adulthood.
This was the case even when the organisms were exposed to a high concentration of nanoplastics for just three hours.
"It's worrying, because this suggests that the organisms have a problem excreting and removing the nanoplastics, which increases the risk of bioaccummulation in the organisms, and subsequently into the rest of the food chain," said Dr Serena Teo, a Senior Research Fellow from the NUS Tropical Marine Science Institute who co-supervised the research.
The nanoplastics were found to have spread all over the larvae's bodies.
According to the researchers, this was because the nanoplastics - which are about 1,000 to 10,000 times smaller than the larvae - are small enough to enter the organisms' bloodstreams and infiltrate cell walls. These nanoplastics can absorb pollutants and chemicals from the water.
“Barnacles may be at the lower levels of the food chain, but what they consume will be transferred to the organisms that eat them," said one of the authors of paper's authors, marine biologist Dr Neo Mei Lin from the Tropical Marine Science Institute at NUS. "In addition, plastics are capable of absorbing pollutants and chemicals from the water."
"These toxins may be transferred to the organisms if the particles of plastics are consumed, and can cause further damage to marine ecosystems and human health."
Associate Professor Suresh Valiyaveettil, who also supervised the research, said that plastic waste is a big concern.
"The lifespan and fate of plastic waste materials in marine environment is a big concern at the moment, owing to the large amounts of plastic waste and its potential impact on marine ecosystem and food security around the world," he said.
However plastics are so prevalent in modern life that we cannot really get rid of them, said Dr Teo.
Instead, she said the study emphasises the importance of waste management - not letting the plastics get into the ocean in the first place.
"It also opens the doors for a lot of ways in how we shall now design new advanced materials," she added, giving the example of green plastics that degrade into inert molecules.
The next step for these researchers is to understand how nanoplastics affect other marine organisms such as tubeworms and sea urchins and, ultimately, how they impact human beings.
The team’s research findings were first published online in the journal ACS Sustainable Chemistry & Engineering in March 2018. The study was funded under the Marine Science Research and Development Programme of the National Research Foundation Singapore.