Agricultural soils now hold 23 times the microplastics the world’s oceans do – and humans could be gobbling them up.

The evaluation also found that soil plastics might be exposed to up to 10,000 chemical additives, most of which were unregulated in agriculture.

“These microplastics are turning food-producing land into a plastic sink,” PhD candidate Joseph Boctor, who led the study, said.

Microplastics and nanoplastics have been detected in lettuce, wheat, and carrot crops through various means including plastic mulching, fertilisers, and even being dropped by clouds.

The study authors said this was “particularly concerning” when seen in the context of microplastics being found in human lungs, brains, hearts, blood, and even placentae.

Many microplastics have been found to contain bisphenol-A (BPA), which has been linked to health conditions including prostate and brain issues in infants and foetuses, as well as blood pressure and heart disease.

But, Boctor claimed, “BPA-free does not equal risk-free”.

“Replacement chemicals like BPF (bisphenol-F) and BPS (bisphenol-S) show comparable or greater endocrine-disrupting activity.”

Boctor said not only was government regulation slower than both scientific finding and industry use, but that the plastic industry lacked transparency around additives it 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, the authors said, 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.

Boctor is among a number of researchers at the Bioplastics Innovation Hub, launched by the CSIRO and Murdoch University, working on the development of a “green plastic” that decomposes properly in soil and water.

“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.”