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September 6, 2012

IZA Responds to PNAS Study on Effects of Nanoparticles on Soybean Plants

Lynn L. Bergeson

The International Zinc Association (IZA) prepared a response to a recent article entitled “Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption” and posted on the Proceedings of the National Academy of Sciences (PNAS) website. IZA states that while the article and related reports highlight that nano-zinc oxide improves crop productivity and zinc concentration in plants, they suggest that the concentration of zinc in plants is negative and poses potential risks to humans. According to IZA, “increased crop production and zinc concentration in plants is an encouraging result and one we would anticipate — indeed, these are the two key objectives of adding zinc fertilizer to crops.” IZA notes that the appendix to the PNAS article states: “[I]ngesting 100g dry soybean mass from our study would deliver approximately 8mg Zn, which is well below the tolerable UIL for adults. Since children would consume less, as their protein requirements are less than adults, they should also not be at risk. Bioaccumulation levels would need to be approximately five times more total Zn than we report to reach bean Zn concentrations that are harmful to human health.” IZA states:

In conclusion, although we find the results of this study, specifically increased crop production and zinc uptake, to be very positive, we have great concern over the inappropriate interpretation of the these results. The risk of over-exposure to zinc in any capacity is negligible compared to the life­threatening reality of underexposure to zinc — which is far and away the bigger, more immediate danger. The misplaced concerns created by this report and the subsequent articles are capable of overshadowing the real problem of zinc deficiency in humans and crops, a serious global issue affecting food security and children’s lives.