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 result in temporary disagglomeration. The released aggregates can be much more mobile and bioavailable while the stimuli is present. Although in our experimental setting we observe reagglomeration once the stimuli are removed, in the environment it may be that the probability of interacting with another nanoparticle aggregate is much lower. . . . The effect of disagglomeration on toxicity has not been considered, or systematically evaluated. This phenomenon warrants attention since it is likely that these metal oxide nanoparticles will experience these natural stimuli during their transport in the environment.

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 health and safety testing; and that nanomaterial products be labeled to delineate all nanoparticle ingredients

4) Any currently existing or future regulatory FDA programs for nanomaterial products must comply with the requirements of the National Environmental Policy Act (NEPA) including . . . that FDA conduct a Programmatic Environmental Impact Statement (PEIS) reviewing the impacts of nanomaterial products on human health and the environment.

Petitioners request that the Commissioner undertake the following actions with regard to nanomaterial sunscreen drug products:

5) Reopen the Administrative Record of the Final Over the Counter (OTC) Sunscreen Drug Product Monograph for the purpose of considering and analyzing information on engineered nanoparticles of zinc oxide and titanium dioxide currently used in sunscreens.

6) Amend the OTC Sunscreen Drug Monograph to address engineered nanoparticles, instructing that sunscreen products containing engineered nanoparticles are not covered under the Mongraph and instead are "new drugs" for which manufacturers must complete a New Drug Application. . . .

7) Declare all currently available sunscreen drug products containing engineered nanoparticles of zinx oxide and titanium dioxide as an imminent hazard to public health and order entities using the nanoparticles in sunscreens regulated by FDA to cease manufacture until FDA's Sunscreen Drug Monograph is finalized and FDA nanotechnology regulations are developed and implemented.

8) Request a recall from manufacturers of all pulically available sunscreen drug products containing engineered nanoparticles of titatium dioxide and/or zinc oxide until the manufacturers . . .complete new drug applications, those applications are approved by the agency, and the manufactureres otherwise comply with FDA's relevant nanomaterial product testing regulations.

FDA held open meetings and established docket FDA -2006-P-0213 (two versions of this docket exist, on Regulations.gov and on the FDA's site). Comments were filed by various stakeholders between 2006 and 2009. Many of these comments, such as those submitted by Purest Colloids Inc and the Cosmetic, Toiletry and Fragrance Association (CFTA) severly criticized the ITCA's petition and urged the FDA not to take the actions requested in the petition.

In an interim response dated Nov. 9, 2006, Randall W. Lutter, then the FDA's Associate Commissioner for Policy and Planning noted that the

. . .FDA has been unable to reach a decision on your petition because it raises complex issues requiring extensive review and analysis by agency officials. . . . We will respond to your petition as soon as we have reached a decision on your requests.

Almost six years later, FDA is still in the process of formulating regulations and policy affecting nanotechnology and nanoindustry.

The parties in the case have been referred by the US Distirct Court to Alternative Dispute Resolution. We will continue to monitor the case and update as warranted.


The parties in International Center for Technology Assessment et al v Hamburg, in a stipulation filed with the court on January 13, 2012, agreed  to grant the EPA " an extension of time to April 23, 2012 to answer, move, or otherwise respond to the complaint". EPA requested the extension "because defendent is working in good faith to respond to the citizen petition . . .on or before April 23, 2012."

As before, we'll keep monitoring and updating as warranted.