Plastic Pollution Hits the Root: Microplastics Disrupt Plant Growth

Do microplastics affect plant growth?

Researchers have discovered that microplastic particles, which are ever present in our global environment, can lower a plant’s ability to carry out photosynthesis. The reduction of a vital biological process utilized by all plants, including food crops (e.g. wheat, rice, and corn) could have unimaginable consequences and lasting effects across the globe. What does this new evidence mean and what are the current implications for humans?

What are microplastics?

Plastics are ubiquitous materials due to their versatility, durability, and strength to lightweight ratio. There are many polymer formulations and the physical characteristics of each is dependent on the chemical manufacturing process. These plastics contain a variety of known and unknown chemicals. Some plastic-associated chemicals are linked to adverse effects on human health such as hormone disruption and increased risk of some cancers. However, there is still a lot we still do not know since many of these chemicals have not been properly studied for their toxicity.

 Plastic pollution has become a growing concern across the world. Large plastic materials are often broken down into smaller particles through exposure to the elements. Microplastics (plastics smaller than 5 mm) retain the same chemical additives and can also be vectors of transport for harmful pathogens and heavy metals. Microplastics have been found in the most remote places on earth like the depths of the ocean, to the top of Mount Everest, and even in the human brain. The discovery of microplastic accumulation in the human body has led to the discovery of many of the harmful effects we know today, but there are still unanswered concerns regarding environmental contaminants.

How are microplastics affecting plants and aquatic species?

The toxins and bacteria that microplastics possess have motivated scientists to better understand their effects on the other organisms that humans require for survival, like plants. Scientists recently found that plants exposed to microplastic particles were found to have reduced growth. 

The study concluded that there are four effects microplastics have on plant growth:

1. Increased production of reactive oxygen species (ROS), which contributes to stress on the plant and stunts its growth.
2. Changes in the chemical composition in the leaf and roots systems, which are vital for obtaining nutrients from the surrounding environment.
3. Alterations in plant hormone regulation, which can stop physical growth and disrupt the overall health and maturation of the plant.
4. Reduction in photosynthesis through alterations in chlorophyll, which are the pigments that give plants their green color and are vital for providing nutrients for the plants by converting sunlight into energy.

Plants are a necessary component of the global food chain as many organisms rely on them as an energy source. As our population growth continues, the maintenance and expansion of food production and air quality will become even more important. However, this expansion is being challenged by the continued accumulation of microplastics in our environment, which is also contributing to the number of reduced crop yields that we are currently experiencing as a result of extreme weather events.

Impact of global photosynthesis reduction on crops and seafood supply

Plants are essential to life on Earth because they can store energy from sunlight through photosynthesis. This energy is used as food that we eat, the natural resources that we burn for fuel and warmth, as well as materials we use for building and clothes like wood and cotton. Basically, life as we know it requires the products of photosynthesis and the materials from plants for survival. Therefore, new emerging studies explaining the effects of microplastic pollution on this essential biological process are concerning and require immediate solutions.

New research has emerged that indicates the devastation that a reduction in photosynthesis will cause. Researchers found that microplastic exposure can reduce photosynthesis production to varying degrees in different ecosystems. It is estimated that photosynthesis is reduced by 7 – 12% in terrestrial crops, 2 – 12% in marine plant life, and 4 – 14% in freshwater algae. The researchers also acknowledged that given the current plastic production rate and lasting microplastic effects, these photosynthesis reduction numbers could lead to a loss of 4 – 13.5% in food crops such as wheat, corn, and rice and a 7% decrease in seafood production over the next 25 years. 

Even a small percentage loss in vital food supplies will have a lasting effect on generations to come and will ultimately grow more desperate for humanity in the future. Therefore, it is vital that we try to provide solutions to this growing challenge now rather than later. The scientists explain that every little bit helps because a 13% reduction in plastic particles can help us avoid a 30% loss in photosynthesis, which translates to 22.15 – 115.73 million metric tons per year in food crops and 0.32 – 7.39 million metric tons per year in seafood. The impacts of a reduction in photosynthesis production will be felt at every level of the food chain and will lead to global food shortages. 

How microplastics' impact on plants could affect air quality

In addition to being a key member of our food supply, plants use photosynthesis to contribute to the global oxygen production and carbon dioxide reduction, which allows us to breathe clean air. A major source of the air that we breathe comes from photoautotroph photosynthesis in the ocean (e.g. plankton). Researchers found that microplastic pollution will reduce the chlorophyll levels of these organisms by 10.96 – 12.84%. The loss of photoautotrophic photosynthesis will be detrimental to the atmospheric oxygen levels, which      are essential for marine life.

What are we doing at RTI to address microplastics’ effects on plants?

RTI uses a multidisciplinary approach that incorporates multiple scientific experts to research and better understand environmental contaminants and their overall effects. Some of the ways that the Institute is addressing this challenge are:

1. Through scientific research

• Characterizing microplastics in different environmental and biological samples
• Uncovering the chemical composition of a variety of microplastics
• Understanding the mechanism of microplastic biological toxicity through various exposure routes
• Investigation of transport and fate of emerging contaminants in soil and air

2. Collaboration with regulatory agencies

• Presenting scientific evidence
• Helping to develop risk assessments
• Providing feedback on regulations and policies

3. Innovation with companies

• Working to reduce microplastic contamination
• Contribute to plastic circularity and more effective plastic usage

There is no doubt that microplastics are contributing to the global pollution problem, which impacts our daily lives through both direct and indirect routes. Through its scientific research and collaborative work, RTI International is working to provide a better understanding of microplastics and promote awareness across the globe. This challenge is a human problem and will take a global effort to make sure current and future generations can live healthier and pollution free lives.