Page 426 - Book Hosokawa Nanoparticle Technology Handbook

FUNDAMENTALS CH. 7 ENVIRONMENTAL AND SAFETY ISSUES WITH NANOPARTICLES
mechanical agitation. However, they reported that the
concentrations were very low. In addition,
measurements of nanoparticle levels during final
packaging of carbon black, which is a typical engi-
neered nanoparticle material, showed that there was
no increase in nearby air [11].

Figure 7.2.14
Mechanism of watermark formation on a silicon wafer References
surface.
[1] A.T. Zimmer, A.D. Maynard: Ann. Occup. Hyg., 46,
663 (2002).
[2] Y. Otani, N. Namiki: Annu. Res. Rep. Smoking Res.
surface is detected in the form of nanometer-sized Found., 747 (2005) (in Japanese).
particles by an electron microscope [8]. [3] M. Suzuki, Y. Yamaji, J. Jpn. Air Cleaning Assoc., 32,
218 (1989) (in Japanese).
(6) Leakage from nanoparticle production processes [4] N. Namiki, Y. Otani, H. Emi and S. Fujii: J. Inst.
In regard to the risks to processing equipments by Environ. Sci., 39, 26 (1996).
nanoparticle leakage from production processes, the [5] K. Kato, A. Tanaka, A. Saiki and J. Hirata: Proc. Air
VDI report in Germany [9] has been described in Cleaning Contam. Control, 5 (1995) (in Japanese).
detail. The production of engineered nanoparticles [6] Y. Ushio, T. Nakamura, S. Shimizu, T. Oshino,
can be generally categorized into two approaches.
One is a “top-down” approach that is initiated with K. Matsuda and T. Arai: Proc. Air Cleaning Contam.
a bulk material and then breaks it into finer pieces Control, 335 (1998) (in Japanese).
using some form of energy such as etching, ball [7] A. Saiki, S. Ro and T. Fujimoto: Chemical
milling, sputtering, and laser ablation. The other Contamination in Semiconductor Processing
approach is to synthesize materials from the atomic Environments and its Countermeasures, Realize, Inc.,
or molecular level by growth and assembly to form Tokyo, 426 (1997) (in Japanese).
the desired nanoparticles. Processes included in this [8] The Japan Society of Industrial Machinery
“bottom-up” category are sol-gel, chemical vapor Manufactures: Report on Behavior Control of
deposition, flame synthesis laser pyrolysis, and Individual Sort of Contaminants – 1993 Report on
so on. Introduction of Advanced Technologies to
Most of these processes are performed in a closed
reaction chamber installed in a cleanroom or associ- Environmental Equipment Industry, 171 (1994) (in
ated controlled environment. Human exposure to Japanese).
these engineered particles does not take place during [9] W. Luther: Industrial Application of Nanomaterials –
synthesis unless there is an unexpected system failure Chance and Risks. Future Technologies, Division of
(e.g. rupture of a seal). Human exposure is more VDI Technologiezentrum, Düsseldorf, Germany,
likely to occur after the manufacturing when opening p. 112 (2004).
the reaction chamber, drying the products, or in the [10] A.D. Maynard, P.A. Baron, M. Foley, A.A. Shvedova,
post-process handling of the products. E.R. Kisin and V. Castranova: J. Toxicol. Environ.
The release of nanoparticles during production Health A, 67, 87 (2004).
chamber cleaning operations is another critical [11] T.A.J. Kuhlbusch, S. Neumann and H. Fissan:
point. Cleaning typically involves using water or
some solvent. Brushes, sponges, or tissues used in J. Occup. Environ. Hyg., 1, 660 (2004).
the cleaning will carry nanoparticles into the waste
stream. Disposal of the waste and wastewater may
become a source of nanoparticle release into the 7.3 Safety of nanoparticles
environment.
Further, conditioning of nanoparticles such as com-
pression, coating, and composition to form final 7.3.1 Problems caused by nanoparticles
products may also result in the release to the environ-
ment and resultant exposure although very few stud- Study on the safety of nanoparticles has started only
ies have been carried out on this subject. Recent recently, and no sufficiently systemized results have
studies [10] to evaluate the aerosol discharge during been obtained. What should be noted in particular is
the handling of carbon nanotubes showed that the that the possibility of radial troubles caused by partic-
generation of nanoparticles occurred under vacuum to ulate matters are considered to increase by the
remove spilled nanotube materials or vigorous decrease of particle diameter in nanoparticles.

400