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Microplastics are 'silently spreading from soil to salad to humans'

A review from Murdoch University has stressed that agricultural soils now hold around 23 times more microplastics than oceans. Among the revelations in the comprehensive evaluation is that plastics in soil may be exposed to up to 10,000 chemical additives, most of which are unregulated in agriculture.

"These microplastics are turning food-producing land into a plastic sink," said Ph.D. candidate Joseph Boctor, who led the study now in Environmental Sciences Europe.

Both microplastics and nanoplastics have now been found in lettuce, wheat and carrot crops. This happens through various means, from plastic mulching, fertilizers and even through being dropped by clouds.

This is particularly concerning when combined with findings of these plastics in the human lungs, brain, heart, blood, and even placenta.

"And BPA-free does not equal risk-free," Boctor said. "Replacement chemicals like BPF and BPS show comparable or greater endocrine-disrupting activity."

The challenge is that regulations are slower than science, and industry is faster than both.

In addition to this, assessing additive toxicity is often overlooked, Boctor said, due to the lack of transparency in the plastic industry and the large number of additives produced.

"This makes the plastic crisis unchecked, and human health exposed," he said. "This review tries to bring this creeping danger under the radar and shine a flashlight on regulators."

Alongside endocrine disruptors, the review pinpointed other additives in soil such as phthalates (linked to reproductive issues), and PBDEs (neurotoxic flame retardants).

These additives have been linked with neurodegenerative disease, increased risks of stroke and heart attack and early death.

"These are not distant possibilities—they are unfolding within biological systems—silently and systematically," Boctor said.

To address this crisis, Boctor is working alongside his colleagues at the Bioplastics Innovation Hub to create a type of plastic that is not only safe, but also decomposes in soil, land and water, leaving behind no legacy.

One innovation currently under development is the Smart Sprays Project—which will demonstrate and test a non-toxic, bioplastic-based spray for soil which forms a water barrier to harvest rainfall and reduce evaporation that can be easily applied with existing farm equipment.

The hope is that through the Hub's work, they will introduce a green plastic to the market that will minimize and eventually negate the need for non-sustainable plastic production worldwide.

"This review highlights the urgent need for coordinated scientific and regulatory efforts," Boctor said. "Regulators, scientists and industry must collaborate to close the loopholes before plastic pollution further entrenches itself in the global food chain."