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Tag Archives: Zinc oxide

Heat and Nanoparticles in Water

As nanoparticles become more commonly used in everyday products  it becomes increasingly important to understand " nanoparticle aggregation in the aqueous environment . . .  for assessing the fate, transport and toxicity of nanomaterials".  In an effort to increase the body of scientific knowledge in this area, Dongxu Zhou, Samuel W. Bennett, and Arturo A. Keller, all of the University of California Santa Barbara Bren School of Environmental Science and Management, in an article published on the PLOS One website "report for the first time . . . temperature variations can cause either agglomeration or disagglomeration . . . depending on the heating and cooling paths. This finding is very relevant . . . , since it indicates that ambient temperature change, constantly occurring in open waters, can alter nanoparticle mobility." Following  studies cited in the article’s references, the authors define aggregates  as "particle clusters bound by irreversible chemical bonds", while agglomerates are "clusters" held together by weak physical interactions. " Once released in the environment, nanoparticles will very likely exist as agglomerated aggregates, i.e. aggregate clusters that have weaker bonds between them. "

In experiments on clusters of three types of metallic oxides – titanium dioxide, zinc oxide, and cerium oxide – lead the authors to conclude

. . . that in open water these soft (weakly bonded) agglomerates can be disagglomerated by common environmental stimuli, such as exposure to sunlight or an increase in temperature from diurnal variations. Although not evaluated, it is likely that mechanical shocks may also …

International Center for Technology Assessment et al v. Hamburg

On December 21, 2011, the International Center for Technology Assessment (ICTA), along with fellow plaintiffs Friends of the Earth (FOE), the Center for Environmental Health, Food and Water Watch, the Institute for Agriculture and Trade Policy, and the Action Group on Erosion, Technology and Concentration filed a complaint in the US District Court for the District of Norther California against Margaret A. Hamburg, Commissioner of the US Food and Drug Administration (FDA), requesting that "this Court enter an Order:

 

(1) Declaring that the Defendants have violated the Administrative Procedure Act by failing to respond to the 2006 Petition within a reasonable time;

(2) Declaring that the Defendants continue to be in violation of the Administrative Procedure Act by failing to respond to the 2006 Petition;

(3) Ordering Defendants to respond to the 2006 Petition as soon as reasonably practicable"

In May of 2006, ICTA filed a "Petition Requesting FDA Amend Its Regulations for Products Composed of Engineered Nanoparticles Generally and Sunscreen Drug Products Composed of Engineered Nanoparticles Specifically". The petition requested "that the Commissioner undertake the following actions with regards to all nanomaterial products:

1) Amend FDA regulations to include nanotechnology definitions necessary to properly regulate nanomaterial products . . . .

2) Issue a formal advisory opinion explaining FDA’s position regarding engineered nanoparticles in products regulated by FDA.

3) Enact new regulations directed at FDA oversight of nanomaterial products establishing and requiring . . .that: nanoparticles be treated as new substances; nanomaterials be subjected to nano-spefic paradigms of …

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