Nano “Trojan Horse” Study Gets Top Billing

John BalbusCal Baier-Anderson, Ph.D., is a Health Scientist.

Each year, the journal Environmental Science & Technology selects a list of Top Papers it has published that are “expected to have a significant and long-lasting impact on the field.” For 2007, its choice for the top environmental science paper addresses a curious facet of the behavior of certain metal oxide nanoparticles:  They can behave as “Trojan horses,” getting inside cultured lung cells and causing significant damage.

The paper, “Exposure of Engineered Nanoparticles to Human Lung Epithelial Cells: Influence of Chemical Composition and Catalytic Activity on Oxidative Stress,” demonstrates that when lung epithelial cells – the type that line the lungs – are exposed in culture to various forms of metal oxides, they readily take them up if they are in the form of nanoparticles, but not if they’re dissolved or in the form of larger particles.  Once inside the cells, the metals generate reactive oxygen species, such as hydrogen peroxide, which can cause a type of damage called oxidative stress.

The authors liken this uptake-and-damage mechanism to that of the Trojan horse:  The nanoparticles appear to “trick” the cells to let them in, and once inside, the toxic metals can wreak havoc.  Have a look at the nifty picture in the accompanying story announcing ES&T’s selection of this paper.  By gaining access to the inside of the cell via nanoparticle transport, metal-generated reactive oxygen species reach critical intracellular targets where they can do damage.

This well-designed study further demonstrates that, while the nano forms of all of the tested metal oxides are preferentially taken up into cultured cells, they differ in their ability to cause oxidative stress.  For example, metal oxide nanoparticles containing cobalt and manganese are much more potent triggers of oxidative stress than those containing iron or titanium.

The major limitation of this study is that it was performed in cell cultures, not in whole animals.  While useful for uncovering mechanisms of toxicity and developing hypotheses for further testing, such in vitro tests do not always perfectly mimic what happens in vivo.  It remains to be seen, therefore, whether the observed effects are also seen in a whole animal study.

This entry was posted in Health Science and tagged . Bookmark the permalink. Both comments and trackbacks are currently closed.

2 Comments

  1. Steven Fowkes
    Posted March 8, 2008 at 10:17 am | Permalink

    Was a oxidative-damage comparison made with an equimolar exposure of the metal oxide as a simple salt?

  2. Cal Baier-Anderson
    Posted March 10, 2008 at 6:18 am | Permalink

    Good question!

    Yes, equimolar amounts of metals were tested. According to the supporting information provided by the authors on the ES&T website (subscription required), the following concentrations were tested, noting that since there are no known titania salts soluble in neutral, aqueous media, titanium was not tested in this component of the study:

    FeCl3 was tested at 0.371 mM, corresponding to 30 ppm Fe2O3,
    MnCl2 was tested at 0.393 mM, corresponding to 30 ppm Mn3O4, and
    CoCl2 was tested at 0.374 mM, corresponding to 30 ppm Co3O4.

  • About this blog

    Science, health, and business experts at Environmental Defense Fund comment on chemical and nanotechnology issues of the day.
    Our work: Chemicals

  • Stay Updated

    Get blog posts and breaking news to your email inbox.

  • Filter posts by tags

    • ADHD (1)
    • aggregate exposure (10)
    • Air Pollution (1)
    • Alternatives assessment (3)
    • American Chemistry Council (ACC) (57)
    • Ami Zota (1)
    • arsenic (3)
    • artificial colors (1)
    • asthma (4)
    • Australia (1)
    • behavior (1)
    • Behind the Label (1)
    • biomonitoring (9)
    • bipartisan (6)
    • bisphenol A (22)
    • blue (1)
    • BP Oil Disaster (18)
    • building code (1)
    • building code official (1)
    • California (1)
    • Canada (7)
    • carbon nanotubes (24)
    • carcinogen (22)
    • Carcinogenic Mutagenic or Toxic for Reproduction (CMR) (12)
    • CDC (7)
    • Center for Science in the Public Interest (1)
    • certified colors (1)
    • Chemical Assessment and Management Program (ChAMP) (13)
    • chemical exposure (2)
    • chemical identity (32)
    • chemical testing (4)
    • Chemicals in Commerce Act (3)
    • Chicago Tribune (6)
    • Children's health (2)
    • children's safety (24)
    • China (10)
    • citizens petition (2)
    • Climate change (1)
    • Clinton (1)
    • color (1)
    • color additive (1)
    • computational toxicology (11)
    • Confidential Business Information (CBI) (58)
    • conflict of interest (8)
    • Congress (1)
    • Congressman Israel (1)
    • consumer products (52)
    • Consumer Specialty Products Association (CSPA) (4)
    • contamination (4)
    • CSPI (1)
    • cumulative exposure (4)
    • data requirements (47)
    • DEHP (1)
    • dermal exposure (1)
    • Design for Environment (1)
    • development (2)
    • developmental (1)
    • diabetes (4)
    • disclosure (2)
    • DNA methylation (4)
    • Drinking Water (7)
    • DuPont (11)
    • Durbin (1)
    • endocrine (2)
    • endocrine disruption (30)
    • environmental justice (1)
    • EPA (4)
    • epigenetics (4)
    • exposure and hazard (49)
    • fast food (1)
    • FD&C (1)
    • FDA (14)
    • fees (1)
    • Firemaster (2)
    • flame retardants (25)
    • Flint (1)
    • food additive (2)
    • food additive petition (2)
    • food additives (2)
    • Food Advisory Comittee (1)
    • food contact substances (1)
    • food dyes (1)
    • formaldehyde (15)
    • fragrances (1)
    • front group (13)
    • GAO (1)
    • general interest (22)
    • Generally Recognizes as Safe (1)
    • George Washington University (1)
    • Globally Harmonized System (GHS) (5)
    • Government Accountability Office (5)
    • GRAS (3)
    • haz (1)
    • hazard (6)
    • High Production Volume (HPV) (23)
    • home buyers (1)
    • home sales (1)
    • Household action level (2)
    • HUD (1)
    • ICC (1)
    • in vitro (14)
    • in vivo (11)
    • industry tactics (44)
    • informed substitution (1)
    • inhalation (18)
    • International Code Council (1)
    • IUR/CDR (27)
    • Japan (3)
    • Lautenberg Act (41)
    • lead (17)
    • lead and copper rule (1)
    • lead dust hazard (1)
    • Lead Exposure (4)
    • lead hazard (1)
    • lead-based paint (3)
    • lead-safe renovator (1)
    • markets (1)
    • Markey (1)
    • MCHM (1)
    • mercury (4)
    • methylmercury (2)
    • microbiome (3)
    • Milken Institute School of Public Health (1)
    • nanosilver (6)
    • National Academy of Sciences (NAS) (20)
    • National Institute for Occupational Safety and Health (NIOSH) (7)
    • National Institute of Environmental Health Sciences (NIEHS) (5)
    • National Nanotechnology Initiative (NNI) (7)
    • National Toxicology Program (1)
    • NCHH (1)
    • NDWA (1)
    • New chemicals (5)
    • NHANES (1)
    • Obama (1)
    • obesity (6)
    • Occupational Safety and Health Administration (OSHA) (3)
    • Office of Information and Regulatory Affairs (OIRA) (4)
    • Office of Management and Budget (OMB) (16)
    • Office of Pollution Prevention and Toxics (OPPT) (3)
    • oil dispersant (18)
    • ortho-phthalate (1)
    • ortho-phthalates (1)
    • paint (1)
    • PBDEs (19)
    • Persistent Bioaccumulative and Toxic (PBT) (22)
    • personal care products (1)
    • pesticides (7)
    • PFOA (1)
    • phthalate (1)
    • phthalates (20)
    • pipes (1)
    • polycyclic aromatic hydrocarbons (PAH) (5)
    • prenatal (6)
    • prioritization (37)
    • Quigley (1)
    • real estate (1)
    • red (1)
    • Redfin (1)
    • renovation (1)
    • rental (1)
    • renters (1)
    • report on carcinogens (1)
    • reproductive (2)
    • residential code (1)
    • revised CSIA (4)
    • right-to-know (1)
    • risk assessment (71)
    • risk evaluation (1)
    • Safe Chemicals Act (24)
    • Safer Chemicals Healthy Families (33)
    • safety (2)
    • Science Advisory Board (1)
    • secrecy (1)
    • Sierra Club (1)
    • Significant New Use Rule (SNUR) (21)
    • Small business (1)
    • snur (1)
    • soil lead hazard (1)
    • South Korea (4)
    • styrene (6)
    • Substances of Very High Concern (SVHC) (15)
    • systematic review (1)
    • TBB (2)
    • test rule (18)
    • Tox21 (5)
    • ToxCast (10)
    • Transparency (1)
    • tributyltin (3)
    • trichloroethylene (TCE) (5)
    • TSCA Modernization Act (14)
    • TSCA Title IV (1)
    • Turkey (3)
    • U.S. states (17)
    • Voluntary (1)
    • vulnerable populations (1)
    • Walmart (3)
    • Washington Post (1)
    • worker safety (23)
    • wristband (2)
    • WV chemical spill (12)
    • yellow (1)
    • Zillow (1)