A study published in _PNAS_ looks at the potential relationship between microplastic pollution and photosynthesis activity.
**Prof Richard Lampitt, Research Scientist at the National Oceanography Centre, said:**
“The topic is of considerable importance but the conclusions should be treated with great caution. I have considerable concerns about the quality of the original data used by the model and this has led to over-speculation about the effects of plastic contamination on primary productivity and food supplies. The effects of a reduction in plastic contamination are even more speculative.”
**Prof Richard Thompson, Professor of Marine Biology, University of Plymouth, said:**
“Microplastics contaminate our plant from the poles to the equator and in my work as a marine biologist from the shoreline to the deep sea it is clear they contaminate rivers lakes and agricultural land. There is clear evidence that exposure leads to uptake by plants and animals and numerous laboratory studies show the potential for harmful effects. This paper adds to that body of evidence which points clearly towards the need for action. The opportunity for such action is at hand via the UN Global Plastic Treaty which is under negotiation. Ensuring the treaty addresses microplastic pollution is of key importance.
“This study gives model predictions that help to highlight the potential for impacts. While these predictions may be refined as new data become available, it is clear from the substantial body of evidence already available that we need to start towards solutions and that is an area where further evidence is critically needed to ensure that any interventions do not result in unintended consequences.”
**Dr Florian Busch,** **Plant Physiologist at the University of Birmingham, said:**
“The paper suggests that there will be an impact on food production through a calculated impact on crop yield, but these findings are speculative.
“While photosynthesis is the driver behind biomass production (and thus yield), the relation between the two is not absolute. A given crop plant might grow somewhat slower under conditions that decrease photosynthesis, but the final plant biomass and yield may remain unchanged, only delayed.”
**Prof Denis Murphy, Emeritus Professor of Biotechnology, University of South Wales, said:**
**“**In this is meta-analysis, the authors review previously published evidence that the presence of environmental microplastics (<5 mm) has the capacity to reduce photosynthetic activity in plants and algae. The work is useful in highlighting the growing body of scientific data on the deleterious effects of these all-pervasive products that are found in global ecosystems from the Arctic to the Amazon. However, there should be a caveat that many of the headline conclusions of the study are based on a series of extrapolations that may not be generally applicable on a global scale.
“For example, it is well known that in vitro exposure to some microplastics can lead to reduced photosynthesis and increased levels of oxidative stress in some algae. However, there are hundreds of microplastic forms that differ significantly in their chemical composition, size, and environmental distribution.
“Several studies on plants have concluded that ‘the effects of microplastics on photosynthetic performance varied with the type and application dose, exposure time, plant tolerance ability, and properties of the plant growth substrate’. Their effects will also differ in the case of microplastics in the soil versus the much smaller microplastics that can be directly absorbed into plant cells. In some cases, these microplastics can directly damage the photosynthetic apparatus, while in other cases they cause various forms of oxidative stress that have much more indirect effects on plant performance.
“The bottom line is that caution should be adopted in taking a ‘one size fits all’ approach to what is a highly complex series of interactions that involve hundreds of pollutant molecules of diverse structure, composition, size and physical properties that are interacting with many thousands of different plant and algal communities in many complex agro-ecosystems around the world.
“In summary, while this analysis is valuable and timely in reminding us of the potential dangers of microplastic pollution and the urgency of addressing the issue, some of the major headline figures require more research before they can be accepted as robust predictions that, for example, might affect policy on food production.”
**‘A global estimate of multiecosystem photosynthesis losses under microplastic pollution’ by Ruijie Zhu _et al._ was published in _PNAS_ at 7pm UK time on Monday 10 March 2025.**
DOI: [https://doi.org/10.1073/pnas.2423957122](https://doi.org/10.1073/pnas.2423957122)
**Declared interests**
Richard Lampitt: _I can confirm that I have no conflict of interest with any of this work._
For all other experts, no reply to our request for DOIs was received.