Toxic nanoparticles in aquatic habitat – 03/30/2004

  • September 30, 2013 at 6:14 pm #414

    Nanoparticles Toxic in Aquatic Habitat, Study Finds
    Mon Mar 29, 6:54 AM ET
    By Rick Weiss, Washington Post Staff Writer

    The first study to look at the health effects of microscopic, manufactured “nanoparticles” on aquatic animals has found troubling evidence that the molecules — which scientists are starting to make for research and industry — can trigger organ damage and other toxic effects.

    At modest concentrations in aquarium water, the minuscule particles — which are made of carbon atoms and are less than one-thousandth the diameter of a human hair — triggered damaging biochemical reactions in the brains of fish. They also wiped out entire populations of “water fleas,” tiny animals that fill an ecologically crucial niche near the bottom of the aquatic food chain.

    The study, described at a scientific meeting yesterday, was small and has yet to be peer reviewed or published in a scientific journal. And although some companies anticipate making tons of the particles within the next few years, current production levels are relatively low, so the risk of exposure for humans and other animals is still quite small.

    Nonetheless, the findings underscore the growing recognition that the hot new field of nanotechnology, which federal officials have said will be at the heart of America’s “next industrial revolution,” may bring with it a number of old-fashioned trade-offs in terms of potential environmental damage and health risks.

    Other animal studies have suggested that a related class of nanoparticles causes lung injuries when inhaled, raising concerns about worker safety in the small but growing number of nanoparticle factories.

    Federal agencies including the Food and Drug Administration (news – web sites), the Environmental Protection Agency (news – web sites) and the Occupational Safety and Health Administration (news – web sites) have acknowledged that current regulations may not adequately protect against nanoparticles’ unique toxicities, but those agencies have only recently begun considering how to respond.

    “There are many potential benefits of nanotechnology, but its hazards and risks are poorly understood,” said Eva Oberdoerster, an environmental toxicologist at Southern Methodist University in Dallas, who led the new studies.

    Nanotechnology is an emerging field of science that deals with engineered molecules a few billionths of a meter in size. Because of the novel arrangements of the atoms in these molecules — and because the laws of physics behave differently at such scales — nanoparticles display bizarre chemical properties. Those properties make them potentially useful in products including stain-proof fabrics and computer components, but also make them potentially biologically disruptive.

    The new research focused on C60 fullerenes, also known as buckyballs, which resemble microscopic soccer balls. Scientists hope to use them as drug delivery systems, components of fuel cells and as tools to clean up contaminated land. But buckyballs can also steal electrons from surrounding molecules — a process known as oxidation and a common mechanism of tissue damage.

    In her experiments, Oberdoerster kept young largemouth bass in 10-liter aquariums filled with fullerene-spiked water at concentrations of 0.5 parts per million — similar to that encountered with more common pollutants in U.S. ports. After 48 hours, the fish were removed and their brains studied for evidence of lipid peroxidation, a tissue-burning chemical reaction that toxicologists use as a standard of biological damage.

    The level of brain damage was “severe,” Oberdoerster reported yesterday at the national meeting of the American Chemical Society in Anaheim — about 17 times higher than seen in fish kept in clean water for comparison.

    “Given the rapid onset of brain damage, it is important to further test and assess the risks and benefits of this new technology before use becomes even more widespread,” she said in a statement.

    In a telephone interview, Oberdoerster said some of the tissue damage may be caused directly by the buckyballs and some may be inflicted by immune system cells responding to the exposure.

    Oberdoerster also found that buckyballs caused die-offs of Daphnia, or water fleas — crustaceans just a few millimeters long that eat algae and serve as food for other aquatic animals. Because of their crucial role in the food chain, Daphnia is a common test organism for aquatic toxicity.

    At about the same concentration used for the fish, half the Daphnia were dead within 48 hours — an effect Oberdoerster characterized as “moderately toxic,” more deadly than nickel but less so than copper.

    The new findings are somewhat surprising because many scientists had predicted that buckyballs would not linger in water but would quickly form clumps and sink, said John R. Bucher, deputy director of the environmental toxicology program at the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., a branch of the National Institutes of Health (news – web sites).

    “Everyone assumed they’d just become part of the muck, if you will,” Bucher said. “This is telling us we need to pay attention to this area.”

    Bucher is part of a multi-year federal effort, still largely in the planning stage, to test the toxicity of several kinds of nanoparticles — an effort made difficult, he noted, because companies have been reluctant to reveal the precise formulas they are using to make their novel nano-products.

    E. Clayton Teague, director of the National Nanotechnology Coordination Office, which advises the White House on nanotechnology issues, said progress in designing those studies is “proceeding very nicely,” though results are still several years away.

    “All of the relevant agencies are now very actively looking at existing regulations to examine the degree to which they do or might not cover adequately these new nanoscale materials,” he said. “I think that most people still believe that with some modifications . . . the existing regulations will be effective in covering these new materials.”

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