Tag Archives: pears

Reliable method for detecting silver nanoparticle in fresh food and produce

The tone of an Aug. 22, 2013 news item on ScienceDaily about detecting silver naooparticles seems a bit alarmist,

Over the last few years, the use of nanomaterials for water treatment, food packaging, pesticides, cosmetics and other industries has increased. For example, farmers have used silver nanoparticles as a pesticide because of their capability to suppress the growth of harmful organisms. However, a growing concern is that these particles could pose a potential health risk to humans and the environment. In a new study, researchers at the University of Missouri have developed a reliable method for detecting silver nanoparticles in fresh produce and other food products. [emphasis mine]

“More than 1,000 products on the market are nanotechnology-based products,” said Mengshi Lin, associate professor of food science in the MU College of Agriculture, Food and Natural Resources. “This is a concern because we do not know the toxicity of the nanoparticles. [emphasis mine] Our goal is to detect, identify and quantify these nanoparticles in food and food products and study their toxicity as soon as possible.” [emphasis mine]

We leap from “could pose a potential health risk” to “we do not know the toxicity” to “study their toxicity as soon as possible” within the space of a few sentences. It’s a bit dizzying for those of us who prefer a more measured approach. The Aug. 22, 2013 University of Missouri news release on EurekAlert, which originated the news item, continues in this vein,

Lin and his colleagues, including MU scientists Azlin Mustapha and Bongkosh Vardhanabhuti, studied the residue and penetration of silver nanoparticles on pear skin. First, the scientists immersed the pears in a silver nanoparticle solution similar to pesticide application. The pears were then washed and rinsed repeatedly. Results showed that four days after the treatment and rinsing, silver nanoparticles were still attached to the skin, and the smaller particles were able to penetrate the skin and reach the pear pulp.

“The penetration of silver nanoparticles is dangerous to consumers because they have the ability to relocate in the human body after digestion,” Lin said. “Therefore, smaller nanoparticles may be more harmful to consumers than larger counterparts.”

When ingested, nanoparticles pass into the blood and lymph system, circulate through the body and reach potentially sensitive sites such as the spleen, brain, liver and heart.

The growing trend to use other types of nanoparticles has revolutionized the food industry by enhancing flavors, improving supplement delivery, keeping food fresh longer and brightening the colors of food. However, researchers worry that the use of silver nanoparticles could harm the human body.

Before I point out one of the other problems I have with this news release, here’s an image that seemingly shows how the silver nanoparticles were applied to the pears,

Caption: Graduate student Zhong Zhang applies silver nanoparticles to a piece of fruit. In a recent study, University of Missouri researchers found that these particles could pose a potential health risk to humans and the environment. Credit: University of Missouri

Caption: Graduate student Zhong Zhang applies silver nanoparticles to a piece of fruit. In a recent study, University of Missouri researchers found that these particles could pose a potential health risk to humans and the environment.
Credit: University of Missouri

Using a syringe to apply silver nanoparticles to a portion of a pear is not the same thing as applying a pesticide in an orchard.  I think it’s problematic to draw conclusions from a testing procedure that does not begin to emulate real life conditions where wind, rain, soil conditions and biological processes come into play.

I have written elsewhere about the difficulties of deciding if silver nanoparticles are good or bad notably in my April 16, 2013 posting, Silver nanoparticles: we love you/we hate you, which features links to various research pieces arguing both pro and con. The Duke University mesocosm project is mentioned in the April 16 posting and is featured in the Feb. 28, 2013 posting, Silver nanoparticles, water, the environment, and toxicity, because it that testing emulated real life conditions.

Reservations about the tone of the news release aside, here’s a link to and a citation for the published paper from the University of Missouri researchers,

Detection of Engineered Silver Nanoparticle Contamination in Pears by Zhong Zhang, Fanbin Kong, Bongkosh Vardhanabhuti, Azlin Mustapha, and Mengshi Lin. J. Agric. Food Chem., 2012, 60 (43), pp 10762–10767 DOI: 10.1021/jf303423q Publication Date (Web): October 19, 2012
Copyright © 2012 American Chemical Society

This article is behind a paywall.