• Accumulation of a nanoparticles within the body can occur due to lack of degradation or excretion.

• Many nanoparticles are not biodegradable.

Very little is understood about possible healtheffects of nanoparticle exposure

SAFETY

Particle Scale

Nanoparticles

Ultrafine RespirablePM 10

1 nm 10 nm 100 nm 1 mm 10 mm

PM 2.5

Definitions- Particle Size

• Nano = Ultrafine = < 100 nm (Conventional)• Nano = <10 nm (suggested by unique quantum and surface-

specific functions)• Fine = 100 nm - 3 mm• Respirable (rat) = < 3 mm (max = 5 mm)• Respirable (human) = < 5 mm (max = 10 mm)• Inhalable (human) = ~ 10 - 50 mm

Inhalation: Inhaled particles induce inflammation in respiratory tract, causing tissue damage. Example: Inhalation of silica particles in industrial workers causes “silicosis”.

Ingestion: nanoparticles may cause liver damage. Ingested nanoparticles (i.e. for oral drug delivery) have been found to accumulate in the liver. Excessive immune/inflammatory responses cause permanent liver damage.

Potential human hazards for nanoscale particulates.

Dermal exposure: Particles may enter body through the skin. Potential hazards are unknown at present.

Other: ocular, ….

6

Nanoparticles affect biological behaviour at cellular, subcellular, protein,and gene levels

Nanoparticle Toxicity

Inhalation

Pulmonary inflammatory reaction

– Persistent inflammation is likely to lead to diseases such as fibrosis and cancer. Thus it is important to control inflammation. This can be done if we can:

- (i) determine the critical dose of particles that initiates inflammation and

- (ii) set exposure limits, according to the relevant metric, so that such a dose cannot be reached within a lifetime exposure scenario.

Possible Health Effects

NP’s Deposit Very Efficiently in the Alveolar Region

Optical micrograph of lung tissue from a rat exposed to single-

wall carbon nanotubes (1 mg/kg) 1 week post exposure. Note

the early development of lesions surrounding the instilled

SWCNT (arrows) and the nonuniform, diffuse pattern of

single-wall carbon nanotube particulate deposition in the lung

(X 100).

Low-magnification micrograph of lung tissue from a rat

exposed to single-wall carbon nanotubes (1 mg/kg) at 1 month

postinstillation. Note the diffuse pattern of granulomatous

lesions (arrows). It was interesting to note that few lesions

existed in some lobes while other lobes contain several

granulomatous lesions—and this was likely due to the

nonuniform deposition pattern following carbon nanotube

instillation. Magnification X 20.

Higher magnification optical micrograph of lung tissue from

a rat exposed to single-wall carbon nanotubes (1 mg/kg) at 1

month postinstillation exposure. Note the discrete, multifocal

mononuclear granuloma centered around the carbon

nanotube material (arrows). Magnification X 400.

D. B. Wahrheit et. al. Toxilogical Sciences 77, 117-125 (2004)

LUNG DEPOSITION OF CARBON NANOTUBES

NTs are totally insoluble and probably one of the most biologically nondegradable man-made materials.Determining how the NT-induced granulomas progress would require a longer-duration study with this biopersistent material.

Fibers are generally of more health hazard than other forms of particulates. It is well established that the pathogenicity of a fiber in the lungs directly correlates with its biopersistency.

Granulomas (miscropic nodules), consisting of particles, live and dead cells, and debris and could impair cellular and physiological (gas exchange) lung functions and give rise to fibrosis, more defined nodules, and other lesions.

NConcerns about granulomas and fibers.

Control of Nanoparticles

Exposure by inhalation

- Filtering respirators or air supplied respirators may be used as a last option to control exposure to nanoparticles.

- Probably the efficiency will be high for all but the smallest nanoparticles (less than 2 nanometers).

- The respirator must fit properly to prevent leakage. The white powder around the

nostrils shows that this mask did not have a tight fit.

Ingestion

Nanoparticles can be swallowed and therefore available for transfer to other body organs via the gastro-intestinal compartment.

Little is currently known about the health effects of nanoparticles on the liver and kidneys as well as the correct metric for describing the nanoparticle dose in these organs.

Another area which merits further research is the transfer of nanoparticles across the placenta barrier. Exposure to nanoparticles during the critical window of fetal development may lead to developmental damage in the offspring.

Possible Health Effects

Control of Nanoparticles

Ingestion exposure

- Occurs from hand-to-mouth contact

- Control by using gloves when handling nanoparticle products

- Hand washing before eating, drinking or smoking is also important

Dermal exposure

• Harmful effects arising from skin exposure may either occur locally within the skin or alternatively the substance may be absorbed through the skin and disseminated via the bloodstream, possibly causing systemic effects.

• Dermal absorption of nanoparticles has not been well investigated and suggested that nanoparticles may penetrate into hair follicles where constituents of the particles could dissolve in the aqueous conditions and enter the skin.

• It is reasonable to postulate that nanoparticles are more likely to penetrate, but this has not yet been demonstrated. Several pharmaceutical companies are believed to be working on dermal penetration of nanoparticles as a drug delivery route.

Possible Health Effects

Control of Nanoparticles

• Skin penetration may occur mainly in the later stages of the process, recovery or surface contamination.

• Some evidence shows that nanoparticles penetrate into the inner layers of the skin and possibly beyond, into the blood circulation.

Skin Exposure

These agencies are conducting studies of potential health risks of nanomaterials:

- The National Institute of Environmental Health Sciences (including the National Toxicology Program);

- The National Institute for Occupational Safety and Health (NIOSH);

- The Environmental Protection Agency (EPA);

- The Department of Defense;

- The Department of Energy (DOE);

- The National Science Foundation (NSF)

- INAIL

Health Risk Studies

ACUTE TOXICITY

Lipid Peroxidation Assay (MDA)Cytotoxicity (necrosis) assay (MTT and LDH Release)

Lipid peroxidation (Malonyldialdehyde, MDA)

LDH ASSAY

Apoptosis assay: (Caspase 3 Activation)Autophagy Assay: Analysis of MAP LC3I to LC3-II Conversion by Western Blot

Long term toxicity Glutathione Assay

In Vitro CharacterizationDetection of Endotoxin Contamination Detection of Microbial ContaminationDetection of Mycoplasma Contamination

Cell Binding/InternalizationAnalysis of Hemolytic Properties of Nanoparticles Analysis of Platelet AggregationAnalysis of Nanoparticle Interaction with Plasma ProteinsCoagulation AssayDetection of Nitric Oxide Production by Macrophages

Concerns raised by in vitro studies on the toxicity of goldnanoparticles include cyanidation of elemental gold in neutrophils,36 initiation of eryptosis,37 spermatoxicity,38 nephrotoxicity,39 and irreversible binding to the major groovesof DNA (although this is specific to 1.4 nm gold nanoparticles).40 In vivo studies have reported gold nanoparticle toxicity detectedas changes in gene expression in the liver and spleen,7 and 41 changes in hematology and blood chemistry indicating liver and kidney damage and an inflammatory response,42 and histological maladies including apoptosis and inflammation in various organs.43, 44 and 45 More recent concerns abouttoxicity such as rashes, proteinuria, and immune disorders haveresulted in abandonment of use of gold in the treatment of patients with rheumatoid arthritis which has motivated the development of newer anti-immune therapies (etanercept, abatacept, and rituximab).