Tag Archives: Jose A. Hernandez-Viezcas

Soybeans and nanoparticles redux

If you read the Feb. 6, 2013 news release on EurekAlert too quickly you might not realize that only one of the two types of the tested nanoparticles adversely affects soybean plants,

Two of the most widely used nanoparticles (NPs) accumulate in soybeans — second only to corn as a key food crop in the United States — in ways previously shown to have the potential to adversely affect the crop yields and nutritional quality, a new study has found. It appears in the journal ACS Nano. [emphasis mine]

Jorge L. Gardea-Torresdey and colleagues cite rapid increases in commercial and industrial uses of NPs, the building blocks of a nanotechnology industry projected to put $1 trillion worth of products on the market by 2015. Zinc oxide and cerium dioxide are among today’s most widely used NPs. Both are used in cosmetics, lotions, sunscreens and other products. They eventually go down the drain, through municipal sewage treatment plants, and wind up in the sewage sludge that some farmers apply to crops as fertilizer. Gardea-Torresdey’s team previously showed that soybean plants grown in hydroponic solutions accumulated zinc and cerium dioxide in ways that alter plant growth and could have health implications.

The question remained, however, as to whether such accumulation would occur in the real-world conditions in which farmers grow soybeans in soil, rather than nutrient solution. Other important questions included the relationship of soybean plants and NPs, the determination of their entrance into the food chain, their biotransformation and toxicity and the possible persistence of these products into the next plant generation. Their new study, performed at two world-class synchrotron facilities — the SLAC National Accelerator Laboratory in California and the European Synchrotron Radiation Facility in Grenoble, France, addressed those questions. “To our knowledge, this is the first report on the presence of cerium dioxide and zinc compounds in the reproductive/edible portions of the soybean plant grown in farm soil with cerium dioxide and zinc oxide nanoparticles. In addition, our results have shown that cerium dioxide NPs in soil can be taken up by food crops and are not biotransformed in soybeans. [emphasis mine] This suggests that cerium dioxide NPs can reach the food chain and the next soybean plant generation, with potential health implications,” the study notes.

The University of Texas El Paso Feb. 6, 2013 news release provides more detail and more clarity about the results of the research ,

Experiments led by Jorge Gardea-Torresdey, Ph.D., of The University of Texas at El Paso (UTEP) have shown that certain man-made nanoparticles that land in soil can be transferred from the roots of plants to the grains, thus entering the food supply via crops grown for human consumption.

Cerium dioxide, which is commonly used in sunscreens and oil refining, remained intact when it was absorbed by the plant, and was transferred all the way into the edible soybean grains. [emphasis mine]

On the other hand, zinc oxide – commonly used in sunscreens and cosmetics – was transferred to the grain, but had broken down to a nontoxic form. [emphasis mine]

To track the nanoparticles’ route within the plants, the researchers used the intense beams of X-rays from the SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource (SSRL) and the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The X-rays also helped reveal whether or not the nanoparticles were chemically transformed in the process.

While studies are under way, Gardea-Torresdey says there is currently little information on the potential health implications of nanoparticles.

UTEP has produced a video titled, UTEP Study Shows Engineered Nanoparticles Can Enter Food Supply. This piece, which features Gardea-Torresdey and a student,  seems to be less about the study and more about the benefits of studying at UTEP and the impact of the Latino community in the US,


Here’s a citation and a link to the article (Note: This work bears a remarkable resemblance to the work mentioned in my Aug. 20, 2012 posting about soybeans and nanoparticles, not least because the studies share three or more authors),

In Situ Synchrotron X-ray Fluorescence Mapping and Speciation of CeO2 and ZnO Nanoparticles in Soil Cultivated Soybean (Glycine max) by Jose A. Hernandez-Viezcas, Hiram Castillo-Michel, Joy Cooke Andrews , Marine Cotte , Cyren Rico, Jose R. Peralta-Videa, Yuan Ge, John H. Priester, Patricia Ann Holden, and Jorge L. Gardea-Torresdey. ACS Nano, DOI: 10.1021/nn305196q Publication Date (Web): January 15, 2013

Copyright © 2013 American Chemical Society

The article is behind a paywall.

Soybeans and nanoparticles

They seem ubiquitous today but there was a time when hardly anyone living in Canada  knew much about soybeans.  There’s a good essay about soybeans and their cultivation in Canada by Erik Dorff for Statistics Canada, from Dorff’s soybean essay,

Until the mid-1970s, soybeans were restricted by climate primarily to southern Ontario. Intensive breeding programs have since opened up more widespread growing possibilities across Canada for this incredibly versatile crop: The 1.2 million hectares of soybeans reported on the Census of Agriculture in 2006 marked a near eightfold increase in area since 1976, the year the ground-breaking varieties that perform well in Canada’s shorter growing season were introduced.

Soybeans have earned their popularity, with the high-protein, high-oil beans finding use as food for human consumption, animal rations and edible oils as well as many industrial products. Moreover, soybeans, like all legumes, are able to “fix” the nitrogen the plants need from the air. This process of nitrogen fixation is a result of a symbiotic interaction between bacteria microbes that colonize the roots of the soy plant and are fed by the plant. In return, the microbes take nitrogen from the air and convert it into a form the plant can use to grow.

This means legumes require little in the way of purchased nitrogen fertilizers produced from expensive natural gas-a valuable property indeed.

Until reading Dorff’s essay, I hadn’t early soybeans had been introduced to the Canadian agricultural sector,

While soybeans arrived in Canada in the mid 1800s-with growing trials recorded in 1893 at the Ontario Agricultural College-they didn’t become a commercial oilseed crop in Canada until a crushing plant was built in southern Ontario in the 1920s, about the same time that the Department of Agriculture (now Agriculture and Agri-Food Canada) began evaluating soybean varieties suited for the region. For years, soybeans were being grown in Canada but it wasn’t until the Second World War that Statistics Canada began to collect data showing the significance of the soybean crop, with 4,400 hectares being reported in 1941. In fact, one year later the area had jumped nearly fourfold, to 17,000 hectares…

As fascinating as I find this history, this bit about soybeans and their international importance explain why research about soyboans and nanoparticles is of wide interest (from Dorff’s essay),

The soybean’s valuable characteristics have propelled it into the agricultural mix in many parts of the world. In 2004, soybeans accounted for approximately 35% of the total harvested area worldwide of annual and perennial oil crops according to the Food and Agriculture Organization of the United Nations (FAO) but only four countries accounted for nearly 90% of the production with Canada in seventh place at 1.3% (Table 2). Soymeal-the solid, high-protein material remaining after the oil has been extracted during crushing-accounts for over 60% of world vegetable and animal meal production, while soybean oil accounts for 20% of global vegetable oil production.

There’s been a recent study on the impact of nanoparticles on soybeans at the University of California at Santa Barbara (UC Santa Barbara) according to an Aug. 20, 2012 posting by Alan on the Science Business website, (h/t to Cientifica),

Researchers from University of California in Santa Barbara found manufactured nanoparticles disposed after manufacturing or customer use can end up in agricultural soil and eventually affect soybean crops. Findings of the team that includes academic, government, and corporate researchers from elsewhere in California, Texas, Iowa, New York, and Korea appear online today in the Proceedings of the National Academy of Sciences.

The research aimed to discover potential environmental implications of new industries that produce nanomaterials. Soybeans were chosen as test crops because their prominence in American agriculture — it is the second largest crop in the U.S. and the fifth largest crop worldwide — and its vulnerability to manufactured nanomaterials. The soybeans tested in this study were grown in greenhouses.

The Aug. 20, 2012 UC Santa Barbara press release has additional detail abut why the research was undertaken,

“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 [UC Santa Barbara’s Bren School of Environmental Science & Management]. “That’s reflected by this type of research.”

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 U.S. –– and because it is vulnerable to MNMs [manufactured nanomaterials]. 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 U.S. 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.

The scientists noted that the EPA requires pretreatment programs to limit direct industrial metal discharge into publicly owned wastewater treatment plants. However, the research team conveyed that “MNMs –– while measurable in the wastewater treatment plant systems –– are neither monitored nor regulated, have a high affinity for activated sludge bacteria, and thus concentrate in biosolids.”

The authors pointed out that soybean crops are farmed with equipment powered by fossil fuels, and thus MNMs can also be deposited into the soil through exhaust.

The study showed that soybean plants grown in soil that contained zinc oxide bioaccumulated zinc; they absorbed it into the stems, leaves, and beans. Food quality was affected, although it may not be harmful to humans to eat the soybeans if the zinc is in the form of ions or salts, in the plants, according to Holden.

In the case of cerium oxide, the nanoparticles did not bioaccumulate, but plant growth was stunted. Changes occurred in the root nodules, where symbiotic bacteria normally accumulate and convert atmospheric nitrogen into ammonium, which fertilizes the plant. The changes in the root nodules indicate that greater use of synthetic fertilizers might be necessary with the buildup of MNMs in the soil.

At this point, the researchers don’t know how zinc oxide nanoparticles and cerium oxide nanoparticles currently used in consumer products and elsewhere are likely to affect agricultural lands. The only certainty is that these nanoparticles are used in consumer goods and, according to Holden, they are entering agricultural soil.

The citation for the article,

Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption by John H. Priester, Yuan Ge, Randall E. Mielke, Allison M. Horst Shelly Cole Moritz, Katherine Espinosa, Jeff Gelb, Sharon L. Walker, Roger M. Nisbet, Youn-Joo An, Joshua P. Schimel, Reid G. Palmer, Jose A. Hernandez-Viezcas, Lijuan Zhao, Jorge L. Gardea-Torresdey, Patricia A. Holden. Published online [Proceedings of the National Academy of Sciences {PNAS}] before print August 20, 2012, doi: 10.1073/pnas.1205431109

The article is open access and available here.