Nanomaterials:-EmergingContaminantsof-Potential- Concern ...©2012O ’Brien&Gere Many(Products(Containing(Nano(on(the(Market(9"! There are approximately 1,500 diverse, mass-consumer

© 2012 O’Brien & Gere

Nanomaterials: Emerging Contaminants of Potential Concern in Georgia's Environment

Charles Barton, Ph.D., DABT

Senior Toxicologist O'BRIEN & GERE


Outline

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Ø Introduc4on Ø Uses Ø Toxicity/exposure Ø Regula4ons Ø Summary/conclusion


Nanomaterials

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Ø Nanotechnology is the engineering and manipula4on of materials at the molecular level

Ø Nanomaterials are 1-‐100 nm in at least one dimension •  A human hair is 50,000 nanometers in diameter

Buzea et al., 2009


Classifica2on of Nanomaterials

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Ø  Natural nanomaterials: They occur in the environment (dusts and mineral composites)

Ø  Incidental nanomaterials (waste or anthropogenic par4cles): They occur as the result of manmade industrial processes (diesel exhaust, coal combus4on, welding fumes)

Ø  Engineered nanomaterials: Man-‐made on purpose; usually engineered nanomaterials have regular shapes, such as tubes, spheres, rings

Exposure to nanomaterial is not new; however, exposure to engineered nanomaterial is.


Categories of Nanomaterials

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Ø Na4onal Academy of Sciences Nanotubes Nanoclays Quantum dots Metal oxides

Ø  EPA Carbon-‐based Metal-‐based Dendrimers Composites

Gajewicz et al., 2012


Classifica2on of Nanomaterials

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Buzea et al., 2009


Lessons Learned from Nano-‐Drug Development

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Soenen et al., 2011


Poten2al Uses of Nanomaterials (Congressional Report 4/13/2012)

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Nanotechnology presents significant commercial opportuni4es for virtually all industry sectors Ø  Detec4on and treatment technologies for cancer and other deadly

diseases Ø  Clean, inexpensive, renewable power through energy crea4on,

storage, and transmission technologies Ø Universal access to clean water Ø  High-‐density memory devices Ø  Higher crop yield and improved nutri4on Ø  Self-‐healing materials Ø  Sensors that can warn of minute levels of toxins and pathogens in

air, soil, or water Ø  Environmental remedia4on of contaminated sites


Many Products Containing Nano on the Market

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Ø There are approximately 1,500 diverse, mass-consumer products containing nanomaterials already on the market •  Sunscreen, moisturizers, and makeup, in the food supply, on roads

in asphalt and sealant, in clothing in sports jackets, slacks, and socks, in personal care products such as toothpaste, in diesel fuel, in paints, in home-building products, in sports equipment such as tennis rackets and hockey sticks, in electronics, in medical devices, in medicine, in food packaging, and in the water purifiers

Ø It has been predicted that nanotechnology will play a role in $1 trillion worth of products by 2015


Proper2es of Nanomaterials

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Ø  Reducing size increases surface area and modifies physicochemical proper4es •  High conduc4vity •  Strength •  Durability •  Chemical reac4vity •  Enhanced permea4on •  Relevant quantum effects

Ø  The same properties making nanomaterials beneficial can make them potentially harmful

Different types of gold nanopar4cles used in the experiments. NR is gold nanorods, HG is hollow gold nanopar4cles, SP is spherical gold nanopar4cles and CS is core-‐shell silica-‐gold nanopar4cles. (Credit: Image courtesy of University of Southampton)

Previously known as a fairly inert material, gold is highly ac4ve in its nanomaterial form


Nanomaterials: A double-‐edged sword

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•  Cross blood-‐brain barrier – impair health •  Placed in subsurface areas – impair ecosystem •  Small, real-‐4me sensors – privacy concerns •  Same compound, different proper4es – regulatory concerns

•  Cross blood-‐brain barrier – drug delivery •  Placed in subsurface areas -‐ remedia4on •  Small, real-‐4me sensors – detec4on & protec4on •  Same compound, different proper4es – novel uses


Risks Associated with Nanomaterials

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Ø Nanomaterials are so small that they may infiltrate human 4ssue or escape into the natural environment in ways that bigger par4cles cannot

Ø Nanomaterials also have large surface areas and are therefore more chemically reac4ve

Ø  Concerns over such risks have led to the crea4on of a new field: nanotoxicology

Ø  Peer-‐reviewed research in nanotoxicology has grown nearly 600% since the year 2000

Ø Much is not known about risks associated with nanomaterials

Nanomaterial related deaths were reported in August 2009. Two women in China who had been exposed to nanomaterials while working in a factory without using respirators died of pleural effusion within two years of their last exposure to the par4cles. An inves4ga4on revealed that the nanomaterials to which they had been exposed had entered their lung 4ssue.


Environmental Risk Concerns Regarding Nanomaterials

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Many unanswered ques4ons Ø What happens to nanomaterial ager product use and disposal? Ø What is the fate of nanomaterial in the environment? Ø  Do nanomaterial degrade? Ø Will nanomaterial accumulate in the food chain? Ø  How to evaluate real world exposures to nanomaterial?

© 2012 O’Brien & Gere 14

Toxicity Data Gaps Remain


Results from Studies on Mul2walled Carbon Nanotubes

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Ø In vitro studies: DNA damage, oxida4ve stress, apoptosis in mammalian cells

Ø In vivo studies: pulmonary toxicity similar to asbestos Ø Promote allergic response in mice; increased chromosomal aberra4ons and micronuclei frequency; suppression of systemic immune func4on; liver injury

Ø Nega4ve effect on reproduc4on poten4al, phenotypic defects, apoptosis, delayed hatching and forma4on of abnormal spinal cords in zebrafish embryo; toxic effects on bacteria


In Vivo Tox Effects of Some Widely Used Nanomaterials

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Ø  Gold nanomaterial: Penetra4on into sperm head and tail Ø  Silver nanomaterial: Blood-‐brain barrier destruc4on and

astrocyte swelling, neuronal degenera4on; induce brain edema forma4on

Ø  Quantum dots: Crosses the placental barrier; penetrates skin Ø  SWCNT: Lung inflamma4on and genotoxicity (similar to

asbestos) Ø  Fullerenes: Toxic effects on oyster development, freshwater

fish, and Daphnia Ø  Metal oxide nanomaterial: Toxic to yeast, bacteria, nematodes,

fish, phytoplankton, and zebrafish


Some Nanomaterials That Can Enter the Brain

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Ø  Carbon nanomaterial Ø  Copper nanomaterial Ø  Iridium nanomaterial Ø Manganese dioxide

nanomaterial Ø  Polystyrene

nanomaterial Ø  Titanium dioxide

nanomaterial Ø  Latex par4cles

nanomaterial Ø Gold nanomaterial


Nanomaterial Hormesis

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Ø  Low doses may be beneficial Ø  Has been demonstrated in both in vitro and in vivo models with

nanomaterials Ø  Low concentra4ons of TiO2 enhances the feeding rate of

terrestrial arthropods Ø  TiO2 s4mulates algal growth at low concentra4ons, but inhibits at

high Ø  Low concentra4ons of SWCNT increases survival of aqua4c

invertebrates, high decreases Ø  Low concentra4ons of copper and zinc nanomaterials s4mulate

ATP concentra4ons in ciliated protozoa Ø  Low concentra4ons of zinc and zinc oxide nanomaterials and

cerium, lanthanum, gadolinium and ylerbium oxide nanomaterials s4mulate growth of a variety of plants, whereas high inhibits


The Dose Makes the Poison

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Ø  Many studies are driven by a desire to demonstrate an effect and to determine underlying mechanisms, which is most easily achieved with high nanomaterial doses

Ø  These doses may never be reached under realis4c exposure condi4ons at the organ of entry or in secondary organs

Ø  Any nanomaterial administered at high enough doses will induce “toxicity”

v In vivo extrapola4on of results from high-‐dose in vitro studies and the interpreta4on of results of high-‐dose in vivo studies need to be undertaken with great cau4on

v People may respond differently than rodents v Mere presence does not equate to toxicity!!!


Regula2on of Nanotechnology

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Ø Countries are assessing risks, but not yet enacting major legislation

Ø Most regulatory agencies in the United States feel that products that employ nanotechnology can be regulated under existing statutes

Ø The Environmental Protection Agency has demonstrated an intent to regulate nanotechnology within the U.S.

Ø  International Organization for Standardization (ISO) Technical Committee 229 on Nanotechnologies •  Terminology and nomenclature; metrology and instrumentation,

including specifications for reference materials; test methodologies; modeling and simulations; and science-based health, safety, and environmental practices


Summary

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Ø Nanomaterials are materials in the 1-‐100 nm range in at least one dimension; can be natural, incidental, or engineered

Ø Use of nanomaterial may revolu4onize most industries Ø Many products containing nanomaterial already on the market

Ø Research and regula4ons are lagging Ø Many ques4ons along the life-‐cycle remain unanswered Ø Do not know environmental concentra4ons or how much people are exposed to

Nanomaterials are emerging contaminants of poten4al concern in Georgia’s environment

© 2012 O’Brien & Gere 22

For more info, visit http://www.nano.gov/

[email protected] 770-‐781-‐1736

Nanomaterials:-EmergingContaminantsof-Potential- Concern ...©2012O ’Brien&Gere Many(Products(Containing(Nano(on(the(Market(9"! There are approximately 1,500 diverse, mass-consumer

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