An Easier Way to Detect Polluted Drinking Water? Go Fish

Glowing zebra fish could be used to identify pollutants in drinking water supplies if a research project under way at the University of Cincinnati proves successful.

The glow comes from firefly genes inserted in the DNA of zebra fish. The fish light up when exposed to PCBs, or polychlorinated biphenyls, which are known to cause cancer in humans.

“These fish are much more sensitive than current water-testing systems that can detect concentrations of PCBs,” said Dr. Daniel Nebert, a professor in the university’s department of environmental health and in the human genetics division of its department of pediatrics.

Using the zebra fish would cost less and take less time than testing the water with equipment or taking samples of mud or fish that then would have to be tested, he said.

The zebra fish are not harmed and eventually lose the glow when removed from the polluted area, Nebert said. And, he added, “they can be detoxed and used again.”

Monte Westerfield, a professor of biology and director of the Zebra Fish International Resource Center at the University of Oregon in Eugene, said he was aware of the Cincinnati research and believes such a project is feasible.

“Zebra fish have been used for years for toxicology and water pollution studies, and researchers have been making transgenic zebra fish for about 20 years,” he said.

The small size of the fish--about an inch long--and their ability to reproduce quickly and in large numbers have contributed to their common use in genetic and biomedical research. Westerfield’s center provides zebra fish from the wild, transgenic zebra fish and frozen sperm for researchers around the world. The center did not provide fish for the Cincinnati project.

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Nebert, who is overseeing the project, said he became interested in using fish as pollution detectors in the 1970s when he heard that the enzyme levels in some fish off the coast of Nova Scotia increased the closer they came to an oil slick.

Nebert first considered using transgenic trout but switched to zebra fish because they are less complex genetically.

Michael Carvan, the assistant research professor conducting the project, said researchers are working with Clermont County, just east of Cincinnati, to apply their studies at Lake Harsha.

“And if it works there, it no doubt would work in other places,” he said.

The researchers will place ordinary zebra fish in tanks filled with lake water to see if they can survive before risking the transgenic fish.

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Paul Russell, a retired biochemist and a water-quality consultant for Clermont County, is excited about the project.

“We have a closed hazardous-waste landfill about five miles up the river from the lake, which serves as a significant amount of drinking water for the county,” he said. “We need very sensitive tests that would alert us to leaks early.”

The plan is to pump lake water into tanks holding the zebra fish, perhaps by late spring. The tanks would be at a pump house that draws water from the east fork of the Little Miami River and in the water intake tower at the lake.