Scientists at the University of Plymouth have shown, for the first time that nanoparticles have a deadly effect on the brain and other parts of the central nervous system.
Nanotechnologies are technologies at the scale of nanometres (10-9m), where new quantum effects can alter the chemistry and physics of elements and compounds, offering possibilities in industrial applications, and for exactly the same reasons, posing unprecedented risks to health and the environment.
Titanium dioxide (TiO2) nanoparticles, found in everything from cosmetics to sunscreen to paint to vitamins, have already been found to cause systemic genetic damage in mice, according to an earlier comprehensive study conducted by researchers at UCLA's Jonsson Comprehensive Cancer Center.
The TiO2 nanoparticles induced single- and double-strand DNA breaks and also caused chromosomal damage as well as inflammation, all of which increase the risk for cancer.
It is a novel mechanism of toxicity, a physicochemical reaction, these particles cause in comparison to regular chemical toxins, which are the usual subjects of toxicological research, Schiestl said.
"The novel principle is that titanium by itself is chemically inert. However, when the particles become progressively smaller, their surface, in turn, becomes progressively bigger and in the interaction of this surface with the environment oxidative stress is induced," he said. "This is the first comprehensive study of titanium dioxide nanoparticle-induced genotoxicity, possibly caused by a secondary mechanism associated with inflammation and/or oxidative stress. Given the growing use of these nanoparticles, these findings raise concern about potential health hazards associated with exposure."
University of Plymouth researchers subjected rainbow trout to titanium oxide nanoparticles which are currently being considered for the food industry. They found that the particles caused vacuoles (holes) to form in parts of the brain and for nerve cells in the brain to die. Although some effects of nanoparticles have been shown previously in cell cultures and other in vitro systems this is the first time it has been confirmed in a live vertebrate.
The results will be presented at the "6th International meeting on the Environmental Effects on Nanoparticles and Nanomaterials" (21st -- 23rd September) at the Royal Society in London.
Nanoparticles may be inhaled, ingested or taken in through contact with the skin. The known possible adverse health impacts include both natural and anthropogenic nanoparticles.
Diseases associated with inhaled nanoparticles include asthma, bronchitis, emphysema, lung cancer, and neurodegenerative diseases, such as Parkinson's and Alzheimer's diseases. Nanoparticles in the gastrointestinal tract have been linked to Crohn's disease and colon cancer. Nanoparticles that enter the circulatory system are implicated in arteriosclerosis, blood clots, arrhythmia, heart diseases, and ultimately death from heart disease. Nanoparticles entering other organs, such as liver, spleen, etc., may lead to diseases of these organs. Some nanoparticles are associated with autoimmune diseases, such as systemic lupus erythematosus, scleroderma, and rheumatoid arthritis.
"It is not certain at this stage of the research whether these effects are caused by the nanoparticles entering the brain or whether it is a secondary effect of nanoparticle chemistry or reactivity," says Professor Richard Handy, lead scientist.
The results of Professor Handy's work and that of other researchers investigating the biological effects of nanoparticles may influence policy regulations on the environmental protection and human safety of nanomaterials.
"It is worrying that the effects on the fish brain caused by these nanoparticles have some parallels with other substances like mercury poisoning, and one concern is that the materials may bioaccumulate and present a progressive or persistent hazard to wildlife and to humans," says Professor Handy.
In an article published in the Journal of Molecular Cell Biology, the Chinese experts said a class of nanoparticles used in medicine, ployamidoamine dendrimers (PAMAMs), may cause lung damage by triggering a type of programed cell death known as autophagic cell death. In experiments, they observed how several types of PAMAMs killed human lung cells.
Patricia Dolez of the Department of Mechanical Engineering, at the Ecole de technologie superieure, in Montreal says there are about 2 million workers involved in nano-related activities. According to the most recent estimates from the U.S. National Science Foundation, the nanotechnology market could reach as much as $1 trillion by 2011/2012. Dolez said that it has already been shown that nanoparticles may affect biological activity through oxidative stress at the cellular and molecular levels, although these effects are yet to be manifest as health problems among workers.
The anticipated hazards associated with this incredibly diverse range of substances falling under the general and broad tag of "nanomaterials" remain largely unknown. And, some scientists have suggested that we are vigilant to emerging health problems associated with nanomaterials. The U.S. government recently updated its National Nanotechnology Initiative strategic plan to highlight the need for an assessment of nanomaterials toxicity before production begins.