Health Hazards and Ethical Concerns of Nanotechnology PDF

HEALTH HAZARDS AND ETHICAL CONCERNS OF NANOTECHNOLOGY  Nanomaterials have at least one primary dimension of less than 100 nanometers, and often have properties different from those of their bulk components that are technologically useful. Because nanotechnology is a recent development, the he...

HEALTH HAZARDS AND ETHICAL CONCERNS OF NANOTECHNOLOGY  Nanomaterials have at least one primary dimension of less than 100 nanometers, and often have properties different from those of their bulk components that are technologically useful. Because nanotechnology is a recent development, the health and safety effects of exposures to nanomaterials, and what levels of exposure may be acceptable, is not yet fully understood. These smaller particles can pose more of a threat to the human body due to their ability to move with a much higher level of freedom while the body is designed to attack larger particles rather than those of the nanoscale.  Nanoparticles have much larger surface area to unit mass ratios which in some cases may lead to greater pro-inflammatory effects in, for example, lung tissue. In addition, some nanoparticles seem to be able to translocate from their site of deposition to distant sites such as the blood and the brain. Nanoparticles can be inhaled, swallowed, absorbed through skin and deliberately or accidentally injected during medical procedures. They might be accidentally or inadvertently released from materials implanted into living tissue. The behavior of nanoparticles is a function of their size, shape and surface reactivity with the surrounding tissue. In principle, a large number of particles could overload the body's phagocytes, cells that ingest and destroy foreign matter, thereby triggering stress reactions that lead to inflammation and weaken the body's defense against other pathogens. Questions about what happens if non-degradable or slowly degradable nanoparticles accumulate in bodily organs, another concern is their potential interaction or interference with biological processes inside the body.  ROUTES OF ENTRY Nanomaterials are able to cross biological membranes and access cells, tissues and organs that larger-sized particles normally cannot. Nanomaterials can gain access to the blood stream via inhalation or ingestion. Broken skin is an ineffective particle barrier, suggesting that acne, eczema, shaving wounds or severe sunburn may accelerate skin uptake of nanomaterials. Then, once in the blood stream, nanomaterials can be transported around the body and be taken up by organs and tissues, including the brain, heart, liver, kidneys, spleen, bone marrow and nervous system. Nanomaterials can be toxic to human tissue and cell cultures (resulting in increased oxidative stress, inflammatory cytokine production and cell death) depending on their composition and concentration.  Mechanisms of toxicity Oxidative stress For some types of particles, the smaller they are, the greater their surface area to volume ratio and the higher their chemical reactivity and biological activity. The greater chemical reactivity of nanomaterials can result in increased production of reactive oxygen species (ROS), including free radicals. ROS production has been found in a diverse range of nanomaterials including carbon fullerenes, carbon nanotubes and nanoparticle metal oxides. ROS and free radical production is one of the primary mechanisms of nanoparticle toxicity; it may result in oxidative stress, inflammation, and consequent damage to proteins, membranes and DNA. For example, the application of nanoparticle metal oxide with magnetic fields that modulate ROS leading to enhanced tumor growth.  Cytotoxicity A primary marker for the damaging effects of NPs has been cell viability as determined by state and exposed surface area of the cell membrane. Cells exposed to metallic NPs have, in the case of copper oxide, had up to 60% of their cells rendered unviable. When diluted, the positively charged metal ions often experience an electrostatic attraction to the cell membrane of nearby cells, covering the membrane and preventing it from permeating the necessary fuels and wastes. With less exposed membrane for transportation and communication, the cells are often rendered inactive. NPs have been found to induce apoptosis in certain cells primarily due to the mitochondrial damage and oxidative stress brought on by the foreign NPs electrostatic reactions.  Genotoxicity Metal and metal oxide NPs such as silver, zinc, copper oxide, uraninite, and cobalt oxide have also been found to cause DNA damage. The damage done to the DNA will often result in mutated cells and colonies as found with the HPRT gene test.  Routes of administration Respiratory Inhalation exposure is the most common route of exposure to airborne particles in the workplace. The deposition of nanoparticles in the respiratory tract is determined by the shape and size of particles or their agglomerates, and they are deposited in the lungs to a greater extent than larger respirable particles. Based on animal studies, nanoparticles may enter the bloodstream from the lungs and translocate to other organs, including the brain. Dermal Some studies suggest that nanomaterials could potentially enter the body through intact skin during occupational exposure. Studies have shown that particles smaller than 1 μm in diameter may penetrate into mechanically flexed skin samples, and that nanoparticles with varying physicochemical properties were able to penetrate the intact skin of pigs. Factors such as size, shape, water solubility, and surface coating directly affect a nanoparticle’s potential to penetrate the skin. Gastrointestinal Ingestion can occur from unintentional hand-to-mouth transfer of materials; this has been found to happen with traditional materials, and it is scientifically reasonable to assume that it also could happen during handling of nanomaterials. Ingestion may also accompany inhalation exposure because particles that are cleared from the respiratory tract via the mucociliary escalator may be swallowed.  ETHICAL CONCERNS According to Andrew Chen, ethical concerns about nanotechnologies should include the possibility of their military applications, the dangers posed by self-replicant nanomachines, and their use for surveillance monitoring and tracking. Risks to environment to public health are treated in a report from the Dutch National Institute for Public Health and the Environment as well as is a report of the European Environment Agency. Academic works on ethics of nanotechnology can be found in the journal Nanoethics. According to the Markkula Center for Applied Ethics possible guidelines for an Ethics of nanotechnology could include: Nanomachines should only be specialized, not for general purpose Nanomachines should not be self replicating Nanomachines should not be made to use an abundant natural compound as fuel Nanomachines should be tagged so that they can be tracked Ethical concern about nanotechnology include the opposition to their use to fabricate Lethal autonomous weapon, and the fear that they may self replicate ad infinitum in a so-called gray goo scenario, first imagined by K. Eric Drexler. Gray goo (also spelled as grey goo) is a hypothetical global catastrophic scenario involving molecular nanotechnology in which out-of-control self-replicating machines consume all biomass on Earth while building more of themselves, a scenario that has been called ecophagy. For the EEA, the challenge posed by nano-materials are due to their properties of being novel, biopersistent, readily dispersed, and bioaccumulative; by analogy, thousands cases of mesothelioma were caused by the inhalation of asbestos dust. Nanotechnology belongs to the class of emerging technology known as GRIN: geno-, robo-, info- nano-technologies. Another common acronym is NBIC (Nanotechnology, Biotechnology, Information Technology, and Cognitive Science). These technologies are hoped – or feared, depending on the viewpoint, to be leading to improving human bodies and functionalities.