Abstract - With the rise of nanotechnology , various nano materials are being used indiscriminately. A general question arise as whether the risk factor of these materials outweigh their main benefits. In this paper, risk produced by the nanomaterials has been briefly explained and the various testing methods that are being conducted are also being described.
Health and Safety regulators are in a state of ambiguity as to decide which nanomaterials comes under safe category and which that does not come. As a result of this, it is really difficult for the scientists to proceed to next step in their research. Time is insufficient inorder to separate good from bad or toxicological assessment. Due to apprehension towards nanomaterial risks, dramatic increase in the safety risk has increased. Many toxicologists are creating batteries of high speed assays inorder to test hundreds and thousands of nanomaterials simultaneously.
NANO MATERIAL RISK
Nano Technology has been the emerging science involving the manipulation of substance at nanometer scale . Along with these positives, there have been increasing concerns over the risk faced by these nano materials. There is a cause for concern regarding the toxicity of some nanomaterials Studies show that soccer-ball shaped carbon fullerenes revealed that the nano particles destroyed the brain cells in fish. Risk assessment involves an assessment of the potential for disclosure and characterization of hazard. Toxicity emerging from nanoparticle exposure would have occurred at the various portals of entry like the lungs and skin.
NANO MATERIAL EXPOSURE
Exposure occurs during development, manufacture, use, or disposal. Almost all substances from arsenic to table salt are toxic to cells, animals and plants at some exposure level. The occurrence of a toxic substance in a consumer product does not comprise a health hazard if the product design or use prevents the consumer from being exposed to the substance. If there is no exposure, then there will be no risks. Inhalation exposure is considered to be main factor for nanomaterial exposure. Airborne concentrations of nanoscale carbon black were undetectable during production hours, while the microscale carbon black particles were observed. These low-nanoscale CNT and carbon black exposures in a ''worst-case'' work setting are thought to be due to the inclination for airborne nanoparticles to agglomerate and dispel due to sedimentation from the air. The shell coatings on engineered nanoparticles that restrict particle-particle interaction and protein binding, such as the polyethylene glycol-coated surfaces of nanoparticles expected for biomedical application, would be expected to lessen this aggregation tendency.
Dermal exposure is another risk factor faced by human .The interface of nanoparticles with skin has received a important attention as a result of the increase in the use of nanoscale particles in a stain-resistant clothing, cosmetics, and sunscreens. Recently research is going on the issue of GI absorption of nano particles following the oral exposure. Like dermal exposure, oral exposure could be a major occupational and environmental route, resulting from intake of infected food and water, the ingestion of inhaled particles, or hand-to mouth shift of particles.
ACTIONS AGAINST TOXICITY
One of the greatest efforts that have been taken is Tox Cast , a five year initiative by researchers was launched in 2007 inorder to speed up toxicity testing on chemicals. Researchers are groping 320 different chemicals, such as pesticides, that all have previously undergone widespread conventional toxicological screens. They are trying to get a broad bioactivity profile for each compound and correlate these with toxicology studies that they have. Computational approach was made to hopefully test the right ones and make some predictions about which materials are of most concern. The compounds determined to be the dangerous will then be given top priority for conventional toxicity test. There has not been a single test that will predict how nanomaterials will behave in vivo. But the batteries of cell assays can help researchers decide which one of them are likely to be safest for the human studies. While the possible benefits of nanotechnology have been broadly reported, little has been done to characterize the safety or identify possible hazards associated with products containing nanoscale materials  .
While the potential benefits of nanotechnology are widely reported, very little has been done to characterize the safety or identify potential hazards associated with products containing nanoscale materials. This emerging technology faces a skeptical and more challenging public where not only their benefits has to be clear but also scientist and engineers should anticipate correctly on the risk connected with these materials. Some incomplete studies have been conducted to evaluate the hazards associated with these materials, but enough hazard and exposure data are not yet available to conduct complete risk assessments for products containing nanoscale materials  . Upbeat research is required to ensure sustainable nanotechnology industry although it is challenging to review the risk of engineering nanomaterials.
- "Can High-Speed Tests Sort Out Which Nanomaterials Are Safe?" ,22 AUGUST 2008 VOL 321 SCIENCE www.sciencemag.org , Published by AAAS.
- Stephan T. Stern1 and Scott E. McNeil "Nanotechnology Safety Concerns Revisited" , Nanotechnology Characterization Laboratory, Advanced Technology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702 Received April 12, 2007; accepted June 14, 2007.
- Treye Thomas,*,1 Karluss Thomas, Nakissa Sadrieh, Nora Savage, Patricia Adair,* and Robert Bronaugh "Research Strategies for Safety Evaluation of Nanomaterials, Part VII: Evaluating Consumer Exposure to Nanoscale Materials", Received November 16, 2005; accepted February 6, 2006.
- Kevin L. Dreher1 "Health and Environmental Impact of Nanotechnology: Toxicological Assessment of Manufactured Nanoparticles" , National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711.
- Vickie L Colvin "The potential environmental impact of engineered nano materials".