• Accumulation of a substance within a species can occur due to lack of degradation or excretion.

• Many nanoparticles are not biodegradable.

• If nanoparticles enter organisms low in the food web, they may be expected to accumulate in organisms higher in the food web.

Very little is understood about possible healtheffects of nanoparticle exposure

Potential bio-accumulation of nanoscale particles.

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 m• Respirable (rat) = < 3 m (max = 5 m)• Respirable (human) = < 5 m (max = 10 m)• Inhalable (human) = ~ 10 - 50 m

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

Study FocusExamples of specific effects investigated

Nanomaterials Tested

Cytotoxicity Affinity to cell membranes, oxidative damage, structure-function relationships, mechanisms

aluminum oxide (Al2O3), cerium oxide (CeO2), cupric oxide (CuO) dendrimers, iron oxide (Fe2O3), nickel oxide (NiO), silicon dioxide (SiO2), titanium dioxide (TiO2), zinc oxide (ZnO)

Dermal toxicity Dermal absorption, cutaneous toxicity,

cadmium celenide (CdSe), fullerenes, iron (Fe)

General toxicity Human blood coagulation, induction of inflammatory gene expression, genotoxicity

aluminum oxide (Al2O3), cadmium celenide (CdSe), cadmium telluride (CdTe) dendrimers, fullerenes, gallium nitride (GaN)Geranium, lead selenide (PbSe), nanofibers, nanowires, quantum dots, silicon dioxide (SiO2), quantum dots, titanium dioxide (TiO2), zinc sulfide (ZnS)

Pulmonary toxicity Oxidative stress, inflammation, surface coating effects, nano/non-nano effects, new/aged agglomerated effects, clearance mechanisms

aluminum oxide (Al2O3), cerium oxide (CeO2), cupric oxide (CuO) dendrimers, gold (Au), iron oxide (Fe2O3), multiwalled nanotubes (MWNT), nickel oxide (NiO), silicon dioxide (SiO2), single walled nanotubes (SWNT), silver (Ag), titanium dioxide (TiO2), zinc oxide (ZnO)

Translocation/Disposition Translocation to sites distant from original exposure, persistence in vivo.

aluminum oxide (Al2O3), iron oxide (Fe2O3), titanium dioxide (TiO2), silicon dioxide (SiO2), zinc oxide (ZnO)

InhalationPulmonary 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.

Wahrheit (Dupont), January 2004.

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

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.

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(Oberdorster 2000).

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.

Concerns about granulomas and fibers.

• Granulomas were observed in lungs 7 d or 90 d after an instillation of 0.5 mg NT per mouse (also in some with 0.1 mg);

• NT, regardless synthetic methods, types and amounts of residual catalytic metals, produced granulomas;

• Lung lesions in the 90-d NT groups, in most cases, more pronounced than those in the 7-d groups.

• Our study shows that, on an equal-weight basis, if carbon nanotubes reach the lungs, they are much more toxic than carbon black and can be more toxic than quartz, which is considered a serious occupational health hazard in chronic inhalation exposures.

• If fine NT dusts are present in a work environment, exposure protection strategies should be implemented to minimize human exposures.

Observations and tentative conclusions.

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.

There is also some evidence that smaller particles can be transferred more readily than their larger counterparts across the intestinal wall (Behrens et al; 2002).

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 ultrafine particles (nanoparticles) has not been well investigated and suggested that ultrafine particles may penetrate into hair follicles where constituents of the particles could dissolve in the aqueous conditions and enter the skin. Direct penetration of the skin has been reported by Tinkle et al (2003) for particles with a diameter of 1000 nm, much larger than nanoparticles.

• 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

Study focusExamples of specific effects investigated

Nanomaterials Tested

Aquatic fate Impact on water migration through soil, chemical behavior in estuarine systems, fate in potable water, uptake by aquatic organisms

alumina, magnetite, nanofibers, silicon carbide, silicon dioxide (SiO2), single walled nanotubes (SWNT), titanium dioxide (TiO2), zinc oxide (ZnO)

Environmental toxicity

Microbial biomass, organic carbon assimilation rates, deposit feeding, uptake, estuarine invertebrates, toxicity in drinking water, fish, frogs, bacteria, fungi, daphnia, algae

cadmium celenide (CdSe), cupric oxide (CuO), iron oxide (Fe2O3), molybdenum disulfide (MoS2), nanofibers, quantum dots, silicon dioxide (SiO2), single walled nanotubes (SWNT), titanium dioxide (TiO2), zinc oxide (ZnO)

Fate in air Emission minimization, sampling and analysis, nucleation rate

fullerenes, silicon dioxide (SiO2), single walled nanotubes (SWNT) sulphuric acid (H2SO4)

Fate in soils/sediment

Desorption and release from nanoparticle surfaces, disposition of contaminants,

aluminum oxide (Al2O3), cadmium celenide (CdSe), hyroxylated fullerenes, magnetite

Cross media fate/Transport

Effects of oxygen, chlorine, UV light

carbon nanofibers, fullerenes, titanium dioxide (TiO2), zinc oxide (ZnO)

Environmental Fate/Transport and Environmental Toxicity

Health Effects: Many questions, not many answers.

• In what ways might employees be exposed to nanomaterials in manufacture and use?  

• In what ways might nanomaterials enter the body during those exposures? 

• Once in the body, where would the nanomaterials travel, and how would they interact physiologically and chemically with the body’s systems? 

• Will those interactions be harmless, or could they cause acute or chronic adverse effects? 

• What are appropriate methods for measuring and controlling exposures to nanometer-diameter particles and nanomaterials in the workplace?

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

- USAThe 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)

Italy : INAIL

Health Risk Studies

Problem areas for regulation of particulates.

PhysicochemicalCharacterizationSize measurement of Nanoparticles Using DLSSize Measurement of Nanoparticles Using Atomic Force MicroscopyMeasuring the Size of Nanoparticles Using Transmission Electron MicroscopyDetermination of NP in Rat BloodQuantification of Free and Chelated Gadolinium Species in Nanoemulsion-Based Magnetic Resonance Imaging Zeta Potential

In Vitro Characterization Detection of Endotoxin ContaminationDetection of Microbial Contamination Detection of Mycoplasma Contamination Cell Binding/Internalization Analysis of Hemolytic Properties of Nanoparticles Analysis of Platelet Aggregation Analysis of Nanoparticle Interaction with Plasma Proteins by 2D PAGECoagulation AssayDetection of Nitric Oxide Production by Macrophages

TOXICITY Oxidative Stress Hep G2 Hepatocyte Glutathione AssayHep G2 Hepatocyte Lipid Peroxidation Assay (MDA)Cytotoxicity (necrosis) assay (MTT and LDH Release)Cytotoxicity (apoptosis) assay (Caspase 3 Activation) Autophagy Assay: Analysis of MAP LC3I to LC3-II Conversion by Western Blot

In Vivo CharacterizationEfficacy Therapeutic Imaging Tissue Distribution Clearance Half-life Systemic exposure (plasma AUC)

Single and Repeat-Dose Toxicity