Tiny metallic particles commonly emitted in vehicle exhaust gasses and agricultural chemicals have been shown to affect the health of soybean crops. Nanoparticles have proven immensely useful in medical and industrial practices, though their environmental impact is still poorly understood.

Nanoparticles are particles with one diameter between 100,000 and one million times smaller than a millimetre. The particles are measured in nanometres (nm). Concerns exist that, despite their increasing use in fuel, medicine, cosmetics and clothing, the particles may have unforeseen effects for the environment if used over a long period of time.

Research from the University of California published by the United States’ National Academy of Sciences last week showed “manufactured nanomaterial (MNM) environmental buildup could profoundly alter soil-based food crop quality and yield.” Californian researchers tested the effects of two nanoparticles on soybean growth; their study yielded troubling results.

The researchers, who claim the recent study is a world first, grew soybeans in greenhouses contaminated with increasing amounts of two widely produced metal oxide MNMs and measured their progress against a control crop. They studied the effects of zinc oxide and cerium oxide nanoparticles on the crops. Zinc oxide is used in cosmetics and, as a result of waste treatment, is frequently present in fertiliser. Cerium is a component of diesel fuel which is intended to reduce emissions.

The Californian team found that the two materials both had potentially adverse effects on crop development. Whilst cerium oxide nanoparticles affected plant growth, diminished yield and interfered with nitrogen fixation, a key function of leguminous crops such as soy and pulses, zinc oxide was “taken up and distributed throughout edible plant tissues.” The fact that zinc particles accumulated in the plants edible parts is of serious concern, as the nanoparticles are thought to be toxic to mammals.

The Californian scientists said their study painted a “clear, but unfortunate, view of what could arise over the long term” as a result of nanoparticle contamination and “forewarn of agriculturally associated human and environmental risks from the accelerating use of MNMs.”

The authors claim that their study shows that, if the use of damaging nanoparticles continues apace before their effects are fully understood, the materials could damage field crops and lead to further use of environmentally damaging chemical fertilisers or enter the food chain and potentially affect humans and wildlife.

Their study is available to view here.

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