Microplastics (MPs), i.e., tiny plastic particles less than 5 millimeters in length, can now be found throughout the ocean and other aquatic ecosystems, and even in our seafood and salt. As MPs have become ubiquitous, scientists have become concerned about the transfer of MPs from the environment to the food chain and the potential impact of MPs on human health.
Scientists from the Chinese Academy of Sciences (CAS) recently found that microplastics are indeed contaminating edible plants, including vegetables we eat. The study was published in Nature Sustainability on July 13.
The study was led by LUO Yongming, a professor both at the Yantai Institute of Coastal Zone Research (YIC) and the Nanjing Institute of Soil Science of CAS.
Most MPs are emitted to the terrestrial environment and accumulate in large amounts in soil. In addition, secondary particles are formed by the degradation of plastics. Wastewater, an important source of water for agricultural irrigation, also contains small-sized MPs.
Despite the prevalence of MPs throughout the environment, the matter of MP uptake by crop plants has not received much attention.
For decades, scientists believed that plastic particles were simply too large to pass through the physical barriers of intact plant tissue. But this new study disproves this assumption.
"Cracks at the emerging sites of new lateral roots of lettuce and wheat crops can take in MPs from the surrounding soil and water. Those MPs can then be transferred from the roots up to the edible parts of the crop," said Prof. LUO.
Scientists already knew that particles as tiny as 50 nanometers in size could penetrate plant roots. But Prof. LUO's group revealed that particles about 40 times that size can get into plants as well.
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