Tuesday, November 21, 2006

Toxic buckyballs in skin cream?

Given that undecorated buckyballs [ie, C60] showed the highest toxicity — about 20 parts per billion, one is a bit surprised by the following:

Zelens Fullerene C-60 Day Cream (HK$1,600)

New to the Hong Kong market, this cream contains a Nobel prize-winning ingredient, Fullerene C-60, which is said to be a powerful neutraliser of free radicals (100 times more effective than the same concentration of vitamin E, according to Zelens). The product is being touted by some as the ultimate time-fighting cream.
[from South China Morning Post, 2 Nov 06]


Blogger Unknown said...

Hello Lawrence,
I just thought I would weigh in on this subject, since I am a research scientist who has worked for several years with C60.

Unfortunately, the study you cite (Colvin) is flawed and inconclusive, and also didn't show toxicity for C60.

It has been refuted by several studies, and one culprit in Colvin's study may have been the tetrahydrafuran used to create what they call "Nano-C60," or nanoparticles of C60. Quite a lengthy process was used to create these, and they are not formed naturally.

At any rate, a search on Pubmed on fullerene and toxicity will show studies begininning in 1991, and several recent good studies, that give data for a null risk for C60 and many derivatives.

Another aspect is that C60 has been lumped by the "nanotechnology" people (Colvin for example is not a toxicologist, but a "nanotechnologist" into the category of nanoparticle.

C60 is a molecule, not a nanoparticle. It is a little less than a nanometer in diameter, so not even that big of a molecule (about the size of Prozac). Nanoparticles (unless one wishes to rewrite Chemistry) are extended solids, just very small in size. In other words, collections of many molecules.

It is unfortunate that "nanotechnology" as a term has become virtually meaningless, since it has tried to encompass too broad of a meaning. C60 is no more of a nanoparticle than H2O (water).

I hope it has been helpful to hear an opinion on this. I know that most serious scientists working with fullerenes share my opionions on this.

2:20 PM  
Blogger Paul Indeglia said...

Dr. Colvin is a chemist at Rice University, the institution that discovered fullerene and that gives her and her colleagues a unique perspective. She is one of the most respected researchers in the field of fullerene technology and a part of the Center for Biological and Environmental Nanotechnology. She and her group have published many articles on the biological effects of fullerene species and some of the articles have presented seemingly conflicting results, but that is not unexpected or unusual in research, especially given the nuances in research methodologies and the newness of the research topic. Recall that we used friable asbestos for hundreds of uses until the mid-1980s without discovering the mechanism for toxicity. Unlike asbestos, there is not an outcry for removing it from the market; scientists are interested in determining its toxicity here at the beginning of its use rather than allowing millions to suffer from biological effects that are presently not clear without additional investigation.

"Nano-C60" is a dispersed fullerene, surface activated through mechanical or chemical means. Given that several publications indicate interference in toxicological response from residual THF, many including me have move to a "water-stirred" nano-C60, made without any solvents. Given that they are being made with only mechanical energy and not chemical facilitation, considerable energy input is required and it takes quite a bit of time at 300 rpm to obtain usable concentrations.

While it may seem infeasible, C60 molecules discharged to a WWTF or a receiving body can receive an incredibly large amount of mechanical mixing, enabling the formation of water-dispersible nano-C60 without the use of a solvent. The issue is complicated when one considers the matrix of chemicals to which C60 might be exposed in the treatment plant or a stream; with its inherent structural stability, C60 in the environment could last a very long time.

C60 is a molecule, yet it is a very insoluble molecule. C60 forms micelles at low concentrations, protecting the hydrophilic surface of the unfunctionalized molecule, forming agglomerates. While C60 has a molecular diameter of 0.7 nm, nano-C60 agglomerates, which are "particles", measure anywhere from about 3 nm to over a 100 nm. Simple stirring results in agglomerates with a mean "particle" size of about 90 nm while sonication yields a much smaller particle size. Given the accepted definition of a nanoparticle as any particle that has as its primary dimension less than 100 nm, nano-C60 is a nanoparticle. Polyhydroxylated fullerene (PHF or fullerenol), which is the product being used in beauty creams, does exist in molecular forms (1.3 nm in diameter) in water-based solutions but can also form agglomerates at higher concentrations.

As for the potential toxicity of fullerene species, we have found adverse biological effects from these nano-C60 particles and PHF on bacteria, algae, and invertebrate species, which stands in conflict with the findings indicating no adverse effect. Our methodology is established by the US EPA and our sample size is large enough to provide statistical significance. Like nearly all products, fullerene has been rushed to market without a full understanding of how it interacts with biota, of course, a complete understanding is pretty much impossible; however, we can continue to develop information for regulators and manufacturers to decide as to whether or not there is an adverse effect worthy of action.

While our perspectives on the potential for toxicity of fullerene species may differ, I would be interested to know what your findings have shown. Presently, this recent data is unpublished but there is a fullerene research group here at the University of Florida that has published several articles on the biological effects of fullerene species and I invite you to contact me so that we can continue to compare information. My email address is indeglia@ufl.edu...or, we can continue this forum.

Paul Indeglia

1:22 PM  

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