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Posted: Apr 11, 2011

Does anyone know how much nanomaterials are produced? Anyone...?

(Nanowerk Spotlight) Life cycle assessment – a cradle-to-grave look at the health and environmental impact of a material, chemical, or product – is an essential tool for ensuring the safe, responsible, and sustainable commercialization of a new technology. With missing data about the large scale impact of nanotechnology, life cycle assessments of potential nanoproducts should form an integral part of nanotechnology research at early stages of decision making as it can help in the screening of different process alternatives. Unfortunately, life cycle studies of emerging nanotechnologies are susceptible to huge uncertainties due to issues of data quality and the rapidly evolving nature of the production processes (see: "Evaluation of 'green' nanotechnology requires a full life cycle assessment").
Part of any meaningful results from a life cycle assessment is the total quantity of the material under investigation. Especially exposure assessments often begin with estimates based on total amounts of a material produced with the assumption that some fraction of the material in question will ultimately released to the environment.
As it turns out, nobody – no research institution, no government agency, no industry association – knows even vaguely how much nanomaterials are manufactured today.
"Obtaining estimates on the potential nanomaterial production capacity is like pulling teeth given the uncertainties, proprietary issues, and rapidly changing landscape," Mark Wiesner, James L. Meriam Professor of Civil & Environmental Engineering at Duke University and Director, Center for the Environmental Implications of NanoTechnology (CEINT) tells Nanowerk. "For that reason it is difficult to pin the potential production values down to even within an order of magnitude. But upper bounds on production amounts, as well as quantification of the uncertainty of production amounts are critical quantities that we need to produce estimates of the potential for exposure to nanomaterials."
In a recent paper in Environmental Science & Technology ("Estimating Production Data for Five Engineered Nanomaterials As a Basis for Exposure Assessment"), Wiesner and his group attempt to estimate upper and lower bound annual United States production quantities for five classes of engineered nanomaterials (ENM) – nanosilver, carbon nanotubes (CNTs), cerium oxide, C60 fullerenes, and nano titanium dioxide.
Since there is no easy way of obtaining production volumes for manufactured nanomaterials, the team had to take an almost criminalistic approach to gather their data. Accessing a variety of sources, the researchers collected data on product types, production capacity, and various other parameters used as proxies for estimating production volume of engineered nanomaterials in the United States (ignoring the impact of imported and exported nanomaterials). Even with this regional focus the task remained almost impossible; getting a grip on worldwide production volumes, and for all engineered nanomaterials, appears to be, at least for now, entirely out of the question.
"Professional reports provide some quantitative data about ENM markets but typically focus on revenue rather than production" says Wiesner. "Production methods and capacity volumes are often considered proprietary and were rarely shared. When the EPA tested their Nanomaterial Stewardship Program for voluntary data reporting, only two companies volunteered any production information. Similarly, when our team tested contacting companies with more formalized requests for information, even when these requests included assurance of confidentiality, there was zero success."
Rather than producing hard data on ENM production, the researchers point out that the key findings of their work are 1) the dearth of production volume information and 2) the inconsistency in viable data sources across various nanomaterials.
In the absence of hard data, the team used refining assumptions to attribute production levels from companies with more reliable estimates to companies with little to no data, to come up with ranges (framed by upper and lower bounds) of projected U.S. production quantities for each of the five ENMs (figures in tons per year):
Product Lower Bound Upper Bound
nano titanium dioxide 7800 38000
nano silver 2.8 20
nano cerium dioxide 35 700
carbon nanotubes 55 1101
fullerenes 2 80
It is striking that these estimates, based on the best available data spanning all sources, still cover at best two and in some cases three orders of magnitude.
The researchers speculate that some materials that have gained high public visibility – notably through being critically assessed by consumer protection and environmental organizations – in personal care, cosmetic, and food and beverage, make their manufacturers less willing to divulge any information.
"On the other end of the spectrum," they write "the most data were gathered for fullerenes. These particles are not currently utilized in a large number of consumer products but are often purchased for highly technological applications or research. With this more technological or scientific audience, perhaps the chance for a manufacturer to set itself apart from others with regard to purity and ability to meet production demands makes sharing production information worthwhile."
Bottomline of this sorry state is that, as long as governments don't compel manufacturers to fully disclose their nanomaterial production data, and instead rely on voluntary schemes that clearly don't work, life cycle assessments will not reflect the real situation.
"Without these data on the magnitude of potential releases, efforts at predicting environmentally relevant concentrations prior to their eventual detection in the natural world will be hampered considerably," concludes Wiesner.
By . Copyright © Nanowerk

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