The pollution of the planet by microplastics is significantly cutting food supplies by damaging the ability of plants to photosynthesise, according to a new assessment.
The analysis estimates that between 4% and 14% of the world’s staple crops of wheat, rice and maize is being lost due to the pervasive particles. It could get even worse, the scientists said, as more microplastics pour into the environment.
About 700 million people were affected by hunger in 2022. The researchers estimated that microplastic pollution could increase the number at risk of starvation by another 400 million in the next two decades, calling that an “alarming scenario” for global food security.
Other scientists called the research useful and timely but cautioned that this first attempt to quantify the impact of microplastics on food production would need to be confirmed and refined by further data-gathering and research.
The annual crop losses caused by microplastics could be of a similar scale to those caused by the climate crisis in recent decades, the researchers behind the new research said. The world is already facing a challenge to produce sufficient food sustainably, with the global population expected to rise to 10 billion by around 2058.
Microplastics are broken down from the vast quantities of waste dumped into the environment. They hinder plants from harnessing sunlight to grow in multiple ways, from damaging soils to carrying toxic chemicals. The particles have infiltrated the entire planet, from the summit of Mount Everest to the deepest oceans.
“Humanity has been striving to increase food production to feed an ever-growing population [but] these ongoing efforts are now being jeopardised by plastic pollution,” said the researchers, led by Prof Huan Zhong, at Nanjing University in China. “The findings underscore the urgency [of cutting pollution] to safeguard global food supplies in the face of the growing plastic crisis.”
People’s bodies are already widely contaminated by microplastics, consumed through food and water. They have been found in blood, brains, breast milk, placentas and bone marrow. The impact on human health is largely unknown, but they have been linked to strokes and heart attacks.
Prof Denis Murphy, at the University of South Wales, said: “This analysis is valuable and timely in reminding us of the potential dangers of microplastic pollution and the urgency of addressing the issue, [but] some of the major headline figures require more research before they can be accepted as robust predictions.”
The new study, published in the journal Proceedings of the National Academy of Sciences, combined more than 3,000 observations of the impact of microplastics on plants, taken from 157 studies.
Previous research has indicated that microplastics can damage plants in multiple ways. The polluting particles can block sunlight reaching leaves and damage the soils on which the plants depend. When taken up by plants, microplastics can block nutrient and water channels, induce unstable molecules that harm cells and release toxic chemicals, which can reduce the level of the photosynthetic pigment chlorophyll.
The researchers estimated that microplastics reduced the photosynthesis of terrestrial plants by about 12% and by about 7% in marine algae, which are at the base of the ocean food web. They then extrapolated this data to calculate the reduction in the growth of wheat, rice and maize and in the production of fish and seafood.
Asia was hardest hit by estimated crop losses, with reductions in all three of between 54m and 177m tonnes a year, about half the global losses. Wheat in Europe was also hit hard as was maize in the United States. Other regions, such as South America and Africa, grow less of these crops but have much less data on microplastic contamination.
In the oceans, where microplastics can coat algae, the loss of fish and seafood was estimated at between 1m and 24m tonnes a year, about 7% of the total and enough protein to feed tens of millions of people.
The scientists also used a second method to assess the impact of microplastics on food production, a machine-learning model based on current data on microplastic pollution levels. It produced similar results, they said.
“Importantly, these adverse effects are highly likely to extend from food security to planetary health,” Zhong and his colleagues said. Reduced photosynthesis due to microplastics may be also cutting the amount of climate-heating CO2 taken from the atmosphere by the huge phytoplankton blooms in the Earth’s oceans and unbalancing other ecosystems.
Prof Richard Lampitt, at the UK’s National Oceanography Centre, said the conclusions should be treated with caution. “I have considerable concerns about the quality of the original data used by the model and this has led to overspeculation about the effects of plastic contamination on food supplies,” he said. The researchers acknowledged that more data was needed and said this would produce more accurate estimates.
The world’s nations failed to reach an agreement on a UN treaty to curb plastic pollution in December, but will restart the talks in August. The scientists said their study was “important and timely for the ongoing negotiations and the development of action plans and targets”.
Prof Richard Thompson, at the University of Plymouth said the new study added to the evidence pointing towards the need for action. “While the predictions may be refined as new data become available, it is clear … that we need to start towards solutions. Ensuring the treaty addresses microplastic pollution is of key importance,” he said.