[Federal Register Volume 77, Number 244 (Wednesday, December 19, 2012)]
[Pages 75169-75171]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-30515]



Centers for Disease Control and Prevention

[Docket Number CDC-2012-0014; NIOSH-260]

Silver Nanoparticles (AgNPs); Information and Comment Request

AGENCY: National Institute for Occupational Safety and Health (NIOSH) 
of the Centers for Disease Control and Prevention (CDC), Department of 
Health and Human Services (HHS).

ACTION: Request for information and comment.


SUMMARY: The National Institute for Occupational Safety and Health 
(NIOSH) of the Centers for Disease Control and Prevention (CDC), as 
part of its mission to investigate new and emerging hazards, has 
initiated an evaluation of the scientific data on silver nanoparticles 
(AgNPs) to ascertain the potential health risks to workers and to 
identify gaps in knowledge so that appropriate laboratory and field 
research studies can be conducted. NIOSH has identified a number of 
relevant publications on AgNPs. This listing (Evaluation of the 
scientific data on silver nanoparticles (AgNPs) can be found in Docket 
CDC-2012-0014 at http://www.regulations.gov.
    NIOSH is requesting additional information on the following: (1) 
Published and unpublished reports and findings from in vitro and in 
vivo toxicity studies with AgNPs, (2) information on possible health 
effects observed in workers exposed to AgNPs, (3) information on 
workplaces and products in which AgNPs can be found, (4) description of 
work tasks and scenarios with a potential for exposure, (5) information 
on measurement methods and, workplace exposure data, and (6) 
information on control measures (e.g., engineering controls, work 
practices, PPE) that are being used in workplaces where potential 
exposures to AgNPs occur.

DATES: Electronic or written comments must be received on or before 
February 19, 2013.

ADDRESSES: You may submit comments, identified by CDC-2012-0014 and 
docket number NIOSH-260, by any of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the instructions for submitting comments.
     Mail: NIOSH Docket Office, Robert A. Taft Laboratories, 
MS-C34, 4676 Columbia Parkway, Cincinnati, OH 45226.
    All information received in response to this notice must include 
the agency name and docket number (CDC-2012-0014; NIOSH-260). All 
relevant comments received will be posted without change to 
www.regulations.gov, including any personal information provided. For 
access to the docket to read background documents or

[[Page 75170]]

comments received, go to www.regulations.gov.

A. Taft Laboratories, 4676 Columbia Parkway, Cincinnati, Ohio 45226, 
telephone (513) 533-8320 or Eileen Kuempel, telephone (513) 533-8363.


    Nanotechnology is generally defined as the intentional manipulation 
of matter to form novel structures with one or more dimension or 
features less than 100 nanometers (nm). Nanotechnology involves a wide 
range of chemistries and almost unlimited types of structures that have 
highly unpredictable interactions with biological systems. Producing 
materials at the nanoscale often results in specific physicochemical 
characteristics that may differ from those of the bulk substance. 
Because of these specific characteristics the use of substances in 
nano-form may pose certain health risks not observed from the use of 
the bulk form of the substance. Nano-silver is one type of nanomaterial 
that may have different physical-chemical characteristics than the bulk 
form of silver. The National Institute for Occupational Safety and 
Health (NIOSH) is interested in gathering data to determine whether a 
health risk to workers may exist from exposure to AgNPs and if specific 
risk management guidance is needed to prevent exposure.
    Several recently reported short-term experimental animal studies 
with AgNPs [Kim et al. 2008, 2009; Sung et al. 2008, 2009; Song et al. 
2012] have shown consistent physiological and toxicological responses 
including: (1) Uptake of AgNPs to the blood and their subsequent 
distribution to all major organs and tissues, (2) decrements in lung 
function and induction of inflammatory responses, and (3) 
histopathology changes in the kidney and especially in the liver, in 
which bile duct hyperplasia was identified as the principal 
toxicological effect. Evidence is available from the 90-day inhalation 
study in Sprague-Dawley rats that AgNPs can deposit in the lung and be 
transported via the blood to the liver [Sung et al. 2008, 2009]. 
Studies also indicate that AgNPs can be transported and deposited in 
major organs and tissues when administered via gavage to Sprague-Dawley 
and F344 rats for 28 and 90 days [Kim et al. 2008, 2010]. A common 
feature of the systemic toxicological effects of AgNPs, irrespective of 
the exposure route, was the onset of histopathological effects to the 
liver in exposed Sprague-Dawley and F344 rats [Sung et al. 2009; Kim et 
al. 2010]. High-dose animals in both studies developed bile duct 
hyperplasia along with some signs of hepatic necrosis. In the 90-day 
oral study, these effects were accompanied by changes in some clinical 
chemistry parameters indicative of perturbations in liver metabolism, 
for example, increases in serum cholesterol concentration and AP 
activity [Kim et al. 2010]. In the 90-day inhalation study of Sung et 
al. [2008, 2009] these systemic effects were accompanied by lung 
function deficits, the development of inflammation responses, and 
alveolar accumulation of macrophages [Sung et al. 2008]. In another 90-
day inhalation study by the same group of researchers [Song et al. 
2012], decreases in lung function and lung inflammation were observed 
in male rats that persisted in the high dose group at 12 weeks after 
cessation of exposure. In female rats, no decrease in lung function was 
observed, and the lung inflammation showed gradual recovery after 
cessation of exposure [Song et al. 2012].
    Published reports on worker exposure to AgNPs are limited but 
indicate the potential airborne release of AgNPs during their 
production [Park et al. 2009; Lee et al. 2011a, b] or as an exposure 
resulting from the electro-refining of silver [Miller et al. 2010].

Information Needs

    Additional data and information are needed to assist NIOSH in 
evaluating the occupational safety and health concerns of working with 
AgNPs. Information is particularly needed for determining the relevance 
of bile duct hyperplasia and hepatocellular necrosis observed in AgNP 
exposed rats, as well as information on: (1) Sources of AgNP exposure, 
(2) factors that influence worker's exposure, (3) in-place exposure 
control measures (e.g., engineering controls) and work practices that 
are effective in reducing worker exposures, and (4) appropriate 
measurement methods and exposure metrics for characterizing workplace 
    NIOSH seeks to obtain materials, including published and 
unpublished reports and research findings, to evaluate the possible 
health risks of occupational exposure to AgNPs. Examples of requested 
information include the following:
    (1) Identification of industries or occupations in which exposures 
to AgNPs may occur.
    (2) Trends in the production and use of AgNPs.
    (3) Description of work tasks and scenarios with a potential for 
exposure to AgNPs.
    (4) Workplace exposure measurement data in various types of 
industries and jobs.
    (5) Case reports or other health information demonstrating 
potential health effects in workers exposed to AgNPs.
    (6) Research findings from in vitro and in vivo toxicity studies, 
including physical-chemical characterization of AgNPs.
    (7) Information on control measures (e.g., engineering controls, 
work practices, PPE) being taken to minimize worker exposure to AgNPs.
    (8) Information on measurement methods and exposure metrics that 
can be used to quantify worker exposure to AgNPs including information 
on the limitations of those methods in quantifying exposures?


Kim YS, Kim JS, Cho HS, Rha DS, Park JD, Choi BS, Lim R, Chang HK, 
Chung YH, Kwon IH, Jeong J, Han BS, Yu IJ [2008]. Twenty-eight day 
oral toxicity, genotoxicity, and gender-related tissue distribution 
of silver nanoparticles in Sprague-Dawley rats. Inhal Toxicol 
Kim W-Y, Kim J, Park JD, Ryu HY, Yu IJ [2009]. Histological study of 
gender differences in accumulation of silver nanoparticles in 
kidneys of Fischer 344 rats. J Toxicol Environ Health Part A 
Kim YS, Song MY, Park JD, Song KS, Ryu HR, Chung YH, Chang HK, Lee 
JH, Oh KH, Kelman BJ, Hwang IK, Yu IJ [2010]. Subchronic oral 
toxicity of silver nanoparticles. Particle Fibre Toxicol 7:20.
Lee JH, Kwon M, Ji JH, Kang CS, Ahn KH, Han JH, Yu IJ [2011a]. 
Exposure assessment of workplaces manufacturing nanosized 
TiO2 and silver. Inhalation Toxicol 23:226-236.
Lee JH, Mun J, Park JD, Yu IJ [2011b]. A health surveillance case 
study of workers who manufacture silver nanomaterials. 
Nanotoxicology DOI: 10.3109/17435390.2011.600840.
Miller A, Drake PL, Hintz P, Habjan M [2010]. Characterizing 
exposures to airborne metals and nanoparticle emissions in a 
refinery. Ann Occup Hyg 54(5):504-513.
Park J, Kwak BK, Bae E, Lee J, Kim Y, Choi K Yi J [2009]. 
Characterization of exposure to silver nanoparticles in a 
manufacturing facility. J Nanopart Res 11:1705-1712.
Song KS, Sung JH, Ji JH, Lee JH, Lee JS, Ryu HR, Lee JK, Chung YH, 
Park HM, Shin BS, Chang HK, Kelman B, Yu lJ [2012]. Recovery from 
silver-nanoparticle-exposure-induced inflammation and lung function 
changes in Sprague Dawley rats. Nanotoxicology DOI:

[[Page 75171]]

Sung JH, Ji HJ, Yoon JU, Kim DS, Song MY, Jeong J, Han BS, Han JH, 
Chung YH, Kim J, Kim TS, Chang HK, Lee EJ, Lee JH, Yu IJ [2008]. 
Lung function changes in Sprague-Dawley rats after prolonged 
inhalation exposure to silver nanoparticles. Inhalation Toxicol 
Sung JH, Ji, JH, Park JD, Yoon, JU, Kim DS, Jeon KS, Song MY, Jeong 
J, Han BS, Han JE, Chung YH, Chang HK, Lee JH, Cho MH, Kelman BJ, Yu 
IJ [2009]. Subchronic inhalation toxicity of silver nanoparticles. 
Toxicol Sci 108:452-461.

    Dated: December 12, 2012.
John Howard,
Director, National Institute for Occupational Safety and Health, 
Centers for Disease Control and Prevention.
[FR Doc. 2012-30515 Filed 12-18-12; 8:45 am]