Testing chemical risk in MN lakes, scientists shrink to the cell level

Dalma Martinovic uses many tools to analyze the potential effects of environmental pollutants in Minnesota lakes. But there's none better than her firefly experiment.

To test for chemicals affecting hormone production, Martinovic uses breast cancer cells with a firefly gene. When the cells are exposed to certain chemicals, they glow like a firefly. The more intense the cell reaction to the chemicals, the brighter the light.

"It's really cool actually," said Martinovic, a researcher at the University of St. Thomas.

It's more than cool. Researchers for years documented low levels of chemicals — from antidepressants to insect repellent — in Minnesota lakes, but they had a hard time answering the question: What's the risk?

Martinovic is working now with the Minnesota Pollution Control Agency and the federal Environmental Protection Agency on techniques to help find answers.

The new tools can assess risk from chemicals found in water at levels as low as a few parts per trillion. In a swimming pool the size of a football field — and four stories deep — a single drop of water would be about one part per trillion.

Digging into the effects of chemicals at the genetic level is a big change for scientists. In the past, a researcher might expose a fish to chemicals and observe what happened. In some cases male fish took on female traits after exposure. In other studies fish behavior changed.

Why those things happened wasn't always clear.

Those studies are still used, but now instead of only observing fish response to chemicals, Martinovic zooms in on individual genes. Are they turned on or off by chemical exposure? Genes create proteins that in turn influence what happens to cells and organs in a fish or human body.

The earliest studies of contaminants involved hormones. Scientists observed reproductive changes in fish exposed to chemicals that interfere with hormone production.

But that was like seeing a blurry photo. Now, by examining how individual genes react to chemicals, the picture is slowly coming into focus.

Early genetic work by Martinovic found fish genes that regulate immune response often changed in response to the chemicals. Genes that regulate hormones nearly always changed when exposed to low levels of chemicals that interact or interfere with hormones.

Because there are many chemicals in water it's also important to understand the cumulative effect. Sometimes more than one chemical will stimulate the same gene to produce a protein. In other cases one chemical will turn on a gene while another has the opposite effect.

"When we talk about genes we say, 'Oh, genes are so important," she said. "Well in a sense, protein is the expression of the gene. It tells you if this gene is turned on it's going to make some protein or it's not going to make some protein. In a sense proteins are the expression of the state of your body."

Another new tool to identify risk is data mining.

The EPA has created a large database of genetic response to a variety of chemicals. It brings together research from around the world.

"We can go to the database and say, I have these four chemicals please list all of the genes that would be impacted by these chemicals. And then we can say, 'OK, what do these processes mean?" Martinovic said. "We can actually then predict what might be happening."

That's the ideal scenario for risk assessment. The problem is there are thousands of chemicals that still need to be tested and added to the database.

Still, genetic risk assessment is helping target research by helping rank chemicals by the potential effects of genetic change they may cause.

That will allow MPCA to decide which chemicals to test for in the environment, and avoid expensive tests for chemicals with limited risk potential, said MPCA scientist Mark Ferrey.

The techniques may provide a better picture the risk to the environment or human health, said Ferrey, who first reported on the widespread discovery of chemicals in Minnesota lakes back in 2009 but confessed he's lost sleep over the question of the risk the chemicals posed.

"Some people will say it's terrible and very frightening that we can have medications in our surface water. And other people will say these chemicals are at such low concentrations it can't possibly make a difference," Ferrey said.

"This is a way to say this is why these things matter to us," he added. "How can we mitigate exposure in the environment? How can we treat them more effectively in treatment plants? How can we remove them from the waste stream?"

Ferrey and Martinovic are using these techniques to prioritize the risk for contaminants in water collected at 10 sites around Minnesota. The findings will be published early next year.

Martinovic is optimistic that within 15 years chemical risk assessment will be much quicker and more detailed.

"It's complex. It's not simple," she said. "But all of this holds great promise."