26-02-2013, 04:48 PM
Unseen hazards
Unseen hazards.pptx (Size: 1.85 MB / Downloads: 22)
INTRODUCTION
No matter how sophisticated knowledge is, it will always be subject to some degree of ignorance. To be alert to—and humble about—the potential gaps in those bodies of knowledge that are included in our decision-making is fundamental. Surprise is inevitable. Just as one basis for scientific research is the anticipation of positive surprises—‘discoveries’—so it will always yield the corresponding prospect of negative surprises. By their nature, complex,
cumulative, synergistic or indirect effects in particular have traditionally been inadequately addressed in regulatory appraisal.
Nano Size
One nanometer is one-billionth of a meter,
about 1/50,000th the width of a strand of hair.
Sub-microscopically small, NPs exhibit unique
properties that are different from even slightly larger sized particles.
express quantum mechanical phenomena & can go places that other particles can’t.
small enough to pass through your skin and even
through the tight mesh of cells that comprise the blood-brain barrier.
Projected benefits
environmentally benign material abundance for all
atomically engineered food and crops
nutritionally enhanced interactive smart’ foods
cheap and powerful energy generation
clean and highly efficient manufacturing
radically improved formulation of drugs, diagnostics and organ replacement
much greater information storage and communication capacities
interactive ‘smart’ appliances
increased human performance
Potential harms of NPs
Studies assessing the role of particle size on toxicity have generally found that ultrafine or nanosize range (<100 nm) particles are more toxic on a massbased exposure metric when compared to larger particles of identical chemical composition.
Studies examining the pulmonary toxicity of carbon nanotubes have provided evidence that intentionally produced nanomaterials can display unique toxicity that cannot be explained by differences in particle size alone..
Nano effects in daily life
At the farm, fertilizers and pesticides containing nanoparticles of clay and other materials are touted for their slow-release mechanisms and potency.
Food itself can contain nanoparticles, such as cured meats and sausages, nano-tea, and the wide variety of nutritional supplements containing nanosilver.
usenanotechnology in myriad aspects of food processing.
In the kitchen, we prepare food using kitchenware and cutting boards that employ anti-microbial nanosilver technology, and store food in refrigerators also coated with nanosilver
Nanotoxicity linked to NPs
• Damage to DNA
• Disruption of cellular function6 and production of reactive oxygen species
• Asbestos-like pathogencity
• Neurologic problems (such as seizures)
• Organ damage, including significant lesions on the liver and kidneys
• Destruction of benefiaacial bacteria in wastewater treatment systems
• Stunted root growth in corn, soybeans, carrots, cucumber and cabbage
• Gill damage, respiratory problems and oxidative stress in fish
TiO2
TiO2 exemplifies the need for regulations specific to the nanoscale.
At larger particle sizes TiO2 is inert and benign
and used in many food products.
sunblocks have historically used TiO2 in larger particle sizes,
But at particle sizes <300 nm, it damage DNA
disrupt cellular function,
produce reactive oxygen species,
cause organ damage.
While skin products containing NPs of TiO2 continue to be sold widely, researchers continue to
Occupational Safety
Documenting evidence that seven workers in a Chinese paint factory either died or suffered permanent lung damage after inhaling fumes and smoke that contained NPs
high exposure rates may render workers de facto guinea pigs for the potential toxicity of nanomaterials.
Occupational safety guidelines can minimize exposure, but until more is known about the potential hazards of nanomaterials,
safe-handling practices may be inadequate