Friday, June 18, 1999

Researchers test fish as toxic alarms

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BY TOM O'NEILL
The Cincinnati Enquirer

Dr. Mike Carvan holds zebra fish. (Jeff Swinger photo) | ZOOM |

        Take 19-cent zebra fish sold in pet stores, scientifically mutate them, inject them with genetic material from lightning bugs, put them in local water sources — and hope they don't turn green.

        The “transgenic” fish are potentially ideal detectors for toxic substances — low-mainte nance, low-cost and self-reproducing. It's too simple, too ingenuous. But pending federal grant approval, will it work?

        The road to that answer gets paved next week.

        In a first-in-the-world program, University of Cincinnati researchers are expected to begin preliminary field tests of water quality at two Clermont County sites, the East Fork of the Little Miami River and Lake Harsha in East Fork State Park.

        “It's one of those "wouldn't it be great if ...' things,” said Dr. Mike Carvan, research assistant professor of environmental health at UC.

        Scientists have discovered that the fluorescent material in lightning bugs and some jellyfish changes color when it comes into contact with certain chemicals, including PCBs. Polychlorinated biphenyls (PCBs), a mixture of chemicals, are toxic and can cause cancer in humans.

        If successful, the fish will provide continual monitoring and are far more sensitive to smaller levels of toxic substances than are current methods. And they are far cheaper to “operate.”

        The first step is to see if the garden-variety zebra danios bought in pet stores can survive in the new environments without food supplements.

        Since the fish are tropical, the heated tanks will be set at 70 to 75 degrees. If they survive, the mutated variety might be next.

        There are no immediate concerns about toxic chemicals at East Fork and Harsha Lake. However, the former CECOS Hazardous Waste Landfill in Jackson Township is about a mile upstream from Pleasant Run Creek, which runs into East Fork.

        CECOS, now operated by BFI, stopped accepting hazardous material in 1990, but hazardous material such as PCBs are stored underground in lined and unlined pits.

        PCBs were once widely used as coolants and lubricants in the manufacture of transformers and other electrical equipment. They haven't been produced in the United States since 1977, but they are still found in the environment. Hundreds of pounds of PCBs are stored at CECOS.

        “This technology is really out front, first in the world,” said Dr. Paul Russell, a water-quality consultant for Clermont County.

        The complexities of molecular biology notwithstanding, here's how it works:

        The fish are mutated so they are striped golden instead of black, a mutation that naturally occurs once in every 10,000 births.

        Genetic material from fireflies, or lightning bugs, and fluorescent jellyfish is injected into the eggs, so that each time the fish reproduce, they will have those characteristics.

        The fish are designed to indicate when the natural receptor system of the fish comes in contact with PCBs and other related compounds.

        That “borrowed” genetic material from the fireflies and jellyfish glows a shade of green when exposed to toxic substances.

        By placing about 100 fish each in 10-gallon tanks at the water intake at East Fork and Lake Harsha, scientists hope the fish will flag the existence of PCBs in the water.

        The gold-stripe mutation is necessary because the resulting color changes from contact with the toxic chemicals is easier to detect against a lighter background.

        The idea was the brainchild of Dr. Paul Nebert, professor of environmental health and pediatrics at UC. Dr. Nebert recently received the Rieveschl Award for Distinguished Scientific Research at UC.

        “You can take a low concentration in the lake, not detectable with a gas chromatograph/mass spectrometer,” Dr. Nebert said. “The fish are 10,000 times more sensitive.”

        In fact, if one dumped a cup of coffee filled with PCBs in the middle of Lake Harsha, according to Dr. Russell, that “small” amount would exceed the Environmental Protection Agency's maximum tolerance level for human consumption in the lake.

        UC researchers happened upon the availability of field sites in Clermont County through an interesting tie:

        Dr. Russell and Dr. Nebert were grad-school lab partners their first year at the University of Oregon Medical School.

        “We've been friends for the past 200 years,” Dr. Russell joked.

       

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