Principles of NanotoxicologyPrinciples of Nanotoxicology

Ivan Pacheco, MD PhD,

Department of Pathology and Molecular Medicine, Queen’s University, Canada,

e-mail: 7bip@queensu.ca

Principles of Nanotoxicology

Outline

•Nanomaterials & biological scale• Why are nanoparticles toxic?• Sources of nanoparticles• Pathways of exposure with nanoparticlesy p p• Conclusions

Nanomaterials and biological scale

By definition, nanomaterialshave at least one dimension inthe nanometer range.

Why are nanoparticles toxic?They enter human body, pass into circulatory, lymphatic systems & organs penetrate systems, & organs, penetrate cells membranes.

Cells & nanoparticles size. Li 2003 Environ Health Persp 111Li 2003 Environ Health Persp 111

Why are nanomaterials potentially toxic?

Nanoparticles interaction with cells

• Depending on chemistry & size - NPs internalized by cells - various locations: cytoplasm, nucleus, mitochondria, lipid vesicles.• NPs internalized by various types of cells: endothelial, epithelial, gastrointestinal, y yp , p , g ,blood, nerve cells.• Nanoparticles influence basic process of cells (proliferation, metabolism, & death).

NPs inside mitochondria [Li Environ. Health Persp]

Cells & nanoparticles size. Li 2003 Environ Health Persp 111

Nanoparticles toxicity

The average percentage of total death for the ten leading causes of death in the United States of America between 1998 and 2006.

Nanomaterials classification

Sources of nanoparticlesp

Generally nanomaterials are Generally, nanomaterials are associated with technology and engineered materials.

However, there are many sources of nanoparticles->

Natural sources of nanoparticles. Dust storms

Asia dust storm sample 2002 (Shi. Z et al, J Geophys Res)

April 2002. (Courtesy of NASA) p ( y f )

Long range migration of mineral dust affects regions thousands of miles away. (After Husar RB et al, J Geophys Res 106) Dust transport across the Pacific ocean in 6 days!

Natural sources of nanoparticles. Volcanoes

Courtesy of NASA-Johnson Space Center)

SEM image of volcanic ash. (Courtesy L Howard)Volcanoes are a major source of nanoparticles.

Anthropogenic sources. Diesel and gas exhaust20 - 130 nm

Health effects

Particle concentration vs distance from highway [Sioutas 2005 Environ Health Res 113]

Engine exhaust particles [Kocbach et al 2006 Part. Fibre Toxicol. 3 1]

Health effects• Motor vehicles - primary source of NPs in urban areas & highways.• Increased mortality among peoples living near major roadways. • Increased myocardial infarction among professional drivers.

R il l i di l d i l i b • Railway locomotive diesel drivers - correlation between exposure to diesel exhaust & incidence of lung cancer.• Increased risk of cardiovascular events in the long term.

Anthropogenic. Engineered nanomaterialsE l f f ti l Examples of free nanoparticles. (a) MWCNTs and (b) ground MWCNTs [Muller Toxicol. Appl. Pharmacol. 207 221](c) Silicon rods ( )[Kevin Robbie, unpublished].

(d) Carbon black, (e) Silver, (f) Titanium dioxide [Soto J. Nanoparticle Res. 7 145](g) Gold nanorods [Wang PNAS 102 15752].(h) Silicon zigzags [Kevin Robbie unpublished][Kevin Robbie, unpublished].

(i) MgF2 helices [Kevin Robbie, unpublished].

Scale bar = 100 nm.

C60 (1nm)( )

Nanoparticles in consumer productsTires, sporting goods, stain-resistant clothing, sunscreens, food additives (colorants)

Health effects• Health effects of NPs inconsumer products not entirely

S t h i t t i t CNT

consumer products not entirelyknown.• Nanotoxicology starts toreveal adverse health effectsof materials previouslyScratch resistant paint CNTs Stain and wrinkle resistantof materials previouslyconsidered safe in bulk.

E.g. silver, used as antibacterialagent toxic to cellsagent - toxic to cells,cytotoxicity > asbestos.Inhalation of Ag nanoparticles⇒migration to olfactory bulb,circulatory system livercirculatory system, liver,kidneys, heart.Ag NPs - found in blood ofpatients with blood diseasesand in colon of patients

Silver nanoparticles - antibacterial http://www.nanotechproject.org/index

and in colon of patientswith colon cancer.

Nanoparticles inhalation.Buzea et alRep Prog Phys

• NPs < 10 µm reach lower airways - alveoli.• Clearance by alveolarmacrophagesmacrophages

Oberdorster 2001 IAOEH 74

Alveolar macrophage(Buzea et al Rep Prog Phys).

Nanoparticles inhalation

Small concentrations of NPs -> distribution to blood brain, heart, kidney.High concentration of NPs -> Aggregates (>100 nm) phagocytized.Very high concentration of NPs -> Macrophage clearance capacity exceeded => lung overload => Diseaseoverload => Disease.

Rat lung lesions induced by various nanoparticles [Muller J 2005 Toxicol Appl Pharmacol 207]

Circulatory system uptake

• Metallic NPs pass rapidly into circulation.• Non-metallic NPs pass very little.• Translocation to organs (liver, heart, spleen, kidney, bone

b i )

Red blood cells in capillaryBuzea C et al Rep Progr Phys

marrow, brain) 3 types blood cells: red cells (oxygen transport)

white cells (fight infections)platelets (prevent bleeding) Buzea C et al Rep. Progr. Physp (p g)

NP uptake by platelets => blood clotting

• Humans with blood disorders - presence of foreign NPs.• Patients with the same type of blood disorder show tissue clots embedding NPs of different compositions (Au, Ag, Co, Ti, Ni, Fe, Cr, Ni, Si, glass, talc, steel).• The common denominator of particles - their size.Cardiovascular malfunction via blood clottingCardiovascular malfunction via blood clotting

Organs uptake of nanoparticles

• Particle debris detected in organs of patients with:

drug addiction - drug addiction - orthopedic implants, - worn dental prostheses, - colon cancer, - Crohn’s disease, - ulcerative colitis.

SEM and EDS spectrum of particles found in patients with dioseased liver and kidneys Gatti 2002 Biomater. 23 2381

Nervous system uptake

NPs (30-50nm) migrate to olfactory nerves, bulb.Brain-blood barrier allows positively charged NPs to pass

Health effectsHealth effects• Neurodegenerative diseases (Alzheimer’s, Parkinson’s disease) - oxidative stress & accumulation of metals (Fe, Cu, Al, Zn. Mn) in brain.

TEM of Fe accumulation in brain of neurologically affected patients. [Quintana J Struct Biol 153 42]

Nanoparticles in the gastro-intestinal tract

Sources• food colorants, pharmaceuticals, water, toothpaste. • Dietary consumption NPs in developed countries is ~ 1012

ti l / d (TiO i d ili t ) particles/person per day (TiO2, mixed silicates).

Translocation• Translocation to blood, spleen, liver, bone marrow, lymph p y pnodes, kidneys, lungs, brain. • NPs constantly found in colon -subjects with cancer, Crohn’sdisease, & ulcerative colitis.• Chemical compositions considered non toxic in bulk

Food colorants: TiO2, Fe-O, silicate (Merck)

• Chemical compositions considered non-toxic in bulk (ceramic, C, Ca, Si, Ag, Stainless Steel).

Ag particles in patients with colon cancer. Gatti Biomater. 25 385

NPs dermal uptake• Occurs at: hair follicle, flexed & broken skin, intracellular.

Health Effects

Podoconiosis

Health Effects• Soil particles => podoconiosis• Silver (antimicrobial effect burns dressing) lethal effect on keratinocytes• Asbestos (roofing, insulation, fire-proofing) autoimmune diseases (immune system destroys or attacks the patient's own body tissue): lupus, rheumatoid arthritis.tissue): lupus, rheumatoid arthritis.

TiO2 sunscreen• Current topic -sunscreen TiO2 penetrate ki t? I it t i ?skin or not? Is it toxic?

Rheumatoid arthritis Systemic lupus erythematosus

Comparison studies of cytotoxicity

In order to assess NPs toxicity - must compare toxicity to those of known toxic particles. ConclusionsAg more toxic than asbestos Nanoparticles morphology & relative cytotoxicity Ag more toxic than asbestos CNTs - extremely toxicTiO2, Al2O3, Fe2O3 ZrO2 less toxic.

Nanoparticles, morphology & relative cytotoxicity index (RCI) on murine macrophage cells[Soto et al 2005 J. Nanoparticle Res. 7 145]

Carcinogenic particles

Many particles are proven to have lung carcinogenic effects in animals or/and humans. (Some PSP substances are shown to be carcinogenic only in rodents, while epidemiologic studies do not clearly indicate human carcinogenicity) After Borm P J A et al Int. J. Cancer 110 3.

Principles of nanotoxicology. Conclusions

• NPs exist widely in nature due to natural sources and pollutionE i d i l ll i if • Engineered nanomaterials - pollution source if not proper

handled and recycled. • Compelling evidence on NPs toxicity

Suggestions to minimize exposure to NPs: • Stringent air quality policyStringent air quality policy• Regulation of dietary & cosmetic NPs• Recycling of products containing nanomaterials

Dr. Ivan Pacheco, e-mail: 7bip@queensu.ca, p@q