Today-May 31
Tiny plastic particles called nanoplastics from everyday items such as plastic containers and straws could accumulate in marine organisms, transfer up the food chain and threaten food safety and human health, said researchers from the National University of Singapore (NUS).
For the first time, a NUS research team working with the acorn barnacle, Amphibalanus amphitrite, demonstrated that nanoplastics – which are less than one micrometre in size and invisible to the naked eye – consumed during the larval stage are retained and accumulated inside the barnacle larvae until they reach adulthood.
In an experiment conducted in November 2016, the team incubated the barnacle larvae in solutions of their regular feed with plastics that were about 200 nanometres in size. The larvae were exposed to two different treatments: acute and chronic.
Barnacle larvae in the acute treatment were kept for three hours in a solution that contained 25 times more nanoplastics than what is currently present in oceans, while those under the chronic treatment were exposed to a solution with low concentrations of nanoplastics for up to four days.
The larvae were then filtered from the solution and examined under a microscope.
“Our results showed that after exposing the barnacle larvae to nanoplastics in both treatments, the larvae had not only ingested the plastic particles, but the tiny particles were found to be distributed throughout the bodies of the larvae,” said Ms Serina Lee from the Tropical Marine Science Institute at NUS on Thursday (May 31). She is the second author of the research paper.
While the barnacles had removed some nanoplastics through moulting and excretion, the team detected continued presence of nanoplastics inside the barnacles as they grew and reached adulthood.
According to the researchers, it is estimated that the oceans may already contain over 150 million tonnes of plastic. Each year, about eight million tonnes of plastic end up in the ocean.
Plastics of all sizes are usually broken down into smaller pieces by the sun, waves, wind and microbial action. These micro- and nanoplastic particles in the water may be ingested by marine organisms such as barnacles, tube worms and sea-squirts.
“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 marine biologist Dr Neo Mei Lin, who is also from NUS’s Tropical Marine Science Institute, and one of the authors of the paper.
“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 in Department of Chemistry at the NUS Faculty of Science, Suresh Valiyaveettil, who co-supervised the research, said that nanoplastics can “enter into animal cells and induce adverse health effects”. He added that further investigation was required for scientists to understand the mechanism.
The NUS 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.
The team is also examining how nanoplastics affect other invertebrate model organisms to understand the impact of plastics on marine ecosystems.
