Hazard Assessment for Understanding Threats From Emerging Nanomaterials
Author: Coming Clean : Contact: comingcleaninc.org
Synopsis and Key Points:
Analysis uncovers health and environmental hazards in nanosilver products already on store shelves, points to haphazard oversight and regulation by EPA.
Researchers have adapted an 'off-the-shelf' hazard assessment tool for use with emerging nanomaterials in an effort to better understand threats they may pose to workers, the public and the environment.
Silver Nanoparticles are silver particles of between 1 nm and 100 nm in size. While frequently described as being silver some are composed of a large percentage of silver oxide due to their large ratio of surface-to-bulk silver atoms. Due to their anti-microbial activities, silver nanoparticles have been incorporated into many consumer products. These products include dietary supplements, laundry detergents, body soap, toothbrushes, toothpaste, disinfectant sprays, kitchen utensils, clothing and children's toys. Exposure to silver nanoparticles has been associated with inflammatory, oxidative, genotoxic, and cytotoxic consequences; the silver particulates primarily accumulate in the liver, but have also been shown to be toxic in other organs including the brain.
As described in the peer-reviewed, scientific journal Environmental Health, researchers focused on characterizing nanosilver products already approved for use by the U.S. Environmental Protection Agency (EPA) and currently found in hundreds of products - and discovered health and environmental hazards not previously considered by EPA during its approval process.
The study was coordinated by scientists working together through the environmental health network Coming Clean, and documents the adaptation of the GreenScreen® for Safer Chemicals comparative hazard assessment method. GreenScreen summarizes known - and missing - information on chemical hazards in an accessible, visual format. It also assigns benchmark scores to substances, and now nanomaterials, based on both known and unknown hazard information. This allows for easy hazard comparisons and an informed way to select safer substitutes to guide product manufacturing.
To demonstrate the adapted method, researchers analyzed a nanosilver product named AGS-20 which has been approved by EPA for use in textiles, such as blankets, plush toys and undergarments, and then compared those findings with an analysis of another nanosilver product EPA used to fill in missing information on AGS-20 and, finally, bulk-form silver. The comparison shows important human health hazards that appear to have been overlooked in EPA's assessment and approval, along with numerous data gaps where health hazards are likely to exist. This finding creates concern that EPA's approach to regulating the rapidly emerging field of nanomaterials is inadequate, and undermines justification for EPA's decision to fill missing information on AGS-20 with information from other forms of nanosilver--which was done against the recommendation of EPA's Scientific Advisory Panel. It also shows that nanosilver materials, currently in hundreds of consumer products, may be harming workers, the public or the environment despite approval by EPA.
The specific findings on the nanosilver materials analyzed show they are highly persistent in the bodies of people and some evidence exists they are toxic to cells. These factors could combine to harm the health of workers who manufacture nanosilver or the consumer products it's included in, as these workers may come in repeated contact with a persistent, toxic material. Nanosilver materials also pose a particularly high threat to aquatic life, which creates an environmental hazard as many nanosilver products may be washed repeatedly and leach nanosilver particles into rivers, lakes and streams.
"Our study demonstrates that the nanosilver product AGS-20 was approved by EPA despite missing substantial information on how it might harm workers or the public," said Jennifer Sass, PhD, and Senior Health Program Scientist with the Natural Resources Defense Council (NRDC), who co-authored the research report. "You can't put the genie back in the bottle, and now that nanosilver products are already on store shelves we hope EPA and manufacturers will consider this study and use it to further protect public health."
"Nanomaterials are a different animal entirely, and as this field continues to expand it's imperative that EPA refine its process for understanding their hazards and regulating their risks appropriately," said Lauren Heine, PhD, and Executive Director of Northwest Green Chemistry, a co-author of the report.
For more background and information on this project.
Background .pdf document on nanomaterials, project findings and recommendations.
comingcleaninc.org/assets/media/documents/GS nanosilver factsheet final.pdf
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