This Is Why Microplastics Are So Hard To Detect In The Ocean

Feb 29, 2020 2:20 PM ET

Liz AllenContributor

Microplastics on a person's fingertip.

By definition, ‘microplastics’ are plastics less than 5mm in size. The variety of sizes, shapes, … [+]


Thanks to major advances in science and technology we can now genetically engineer genes with increasing precision, isolate specific proteins from cells, and accurately sequence entire genomes. So why have we been unable to develop a robust way to detect microplastics?

Unlike DNA and proteins, plastics are not alive. Here’s why that’s essential to understanding the plastic detection problem.

While scientists take advantage of the sequences within DNA or the affinity of antibodies for specific proteins, these techniques do not work on microplastics since they are just made of chemicals – without any proteins, DNA sequences, or otherwise life-related structures for scientists to use for detection.

A pair of hands holding microplastics collected at the beach.

Microplastics like these end up in our ocean. However, the actual amount of microplastics is not … [+]

imple water filtering techniques are not the solution either. Filtering and sorting out microplastics is inefficient and carries a high risk inaccuracy since many plastics are transparent and come in many different sizes. In other words, it’s hard to separate the microplastics from the natural pieces of the environment.

Some labs use high-tech lasers or mass-spectrometers to identify plastics, but these methods are not only technically challenging, but also quite expensive.

The difficulties of detecting marine microplastics have caused many labs around the world to develop different ways to study these plastics. While an impressive show of creativity, the many different methods make it challenging, if not outright impossible, to compare studies between labs. In other words, a consensus is needed in the world of microplastic detection and data reporting for the problem to be understood on a larger scale.

A funnel with a yellow peroxide solution for separating microplastics out of water.

NOAA’s microplastics protocol suggests separating plastics in water samples by adding the sample to … [+]


The National Oceanic and Atmospheric Administration’s (NOAA) Marine Debris Program attempted to standardize microplastic detection methods with their publication of step-by-step instructions for quantifying marine microplastics in environmental samples in 2015. NOAA’s recommended methods suggest inexpensive but laborious filtering and microscopic analysis paired with simple chemical manipulation.

In 2018, JPI-Oceans also published a “Standardized Protocol for Monitoring Microplastics in Sediments”. While this protocol also suggests size-separation and visual analyses to detect microplastics, it also recommends a deeper analysis of the microplastics using various types of spectrometry.

A scientist loads vials into a mass spectrometer. These machines can identify microplastics.

Some scientists use various types of mass spectrometry to detect and identify microplastics in water … [+]


Importantly, both of these protocols highlight the risk of contamination. With the abundance of microplastics in our everyday clothes and packaging materials, researchers must be careful to avoid adding lab-borne microplastics to their environmental samples.

While true consensus on how to detect and quantify microplastics is still being coordinated, the scientific community is nonetheless working hard to provide important data on how microplastics have infiltrated our marine world.

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