Toxicity // Soybean Susceptibility to Manufactured Nanomaterial With Evidence for Food Quality and Soil Fertility Interruption © Based on Material by UCSB, USA

Nanoparticles eventually end up in agricultural soil, which is a cause for concern, according to a group of environmental scientists that recently carried out the first major study of soybeans grown in soil contaminated by two manufactured nanomaterials (MNMs). The team was led by scientists at UC Santa Barbara‘s Bren School of Environmental Science & Management, USA.

"Our society has become more environmentally aware in the last few decades, and that results in our government and scientists asking questions about the safety of new types of chemical ingredients," said senior author Patricia Holden, a professor with the Bren School. "That‘s reflected by this type of research."

She explained that the research, which is funded by the National Science Foundation (NSF) and the U.S. Environmental Protection Agency (EPA), is helping to discover potential environmental implications of a new industry that includes nanomaterials. The ultimate goal is to help find more environmentally compatible substitutes, Holden said.

Soybean was chosen for the study due to its importance as a food crop – it is the fifth largest crop in global agricultural production and second in the US – and because it is vulnerable to MNMs. The findings showed that crop yield and quality are affected by the addition of MNMs to the soil.

The scientists studied the effects of two common nanoparticles, zinc oxide and cerium oxide, on soybeans grown in soil in greenhouses. Zinc oxide is used in cosmetics, lotions, and sunscreens. Cerium oxide is used as an ingredient in catalytic converters to minimize carbon monoxide production, and in fuel to increase fuel combustion. Cerium can enter soil through the atmosphere when fuel additives are released with diesel fuel combustion.

The zinc oxide nanoparticles may dissolve, or they may remain as a particle, or re-form as a particle, as they are processed through wastewater treatment. At the final stage of wastewater treatment there is a solid material, called biosolids, which is applied to soils in many parts of the US. This solid material fertilizes the soil, returning nitrogen and phosphorus that are captured during wastewater treatment. This is also a point at which zinc oxide and cerium oxide can enter the soil.