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Tumors and sex changes: a goby story 

Cal Poly researchers suspect a chemical is affecting Morro Bay fish

click to enlarge POISONED :  Cal Poly biologists thought Morro Bay goby fish were just pregnant before they cut them open and found liver tumors. - PHOTO COURTESY OF SARAH JOHNSON
  • POISONED : Cal Poly biologists thought Morro Bay goby fish were just pregnant before they cut them open and found liver tumors.

It’s hard not to see the irony: A common chemical sometimes used in spermicides may be turning fish into hermaphrodites.

The chemical is called nonylphenol (pronounced “non-il-fe-NALL”) and it is increasingly being eyed as the cause of some unexpected developments in goby fish.

The compound is used most commonly for industrial purposes, but is also a common ingredient in detergents, cosmetic products, and spermicides.

Studies suggest the chemical could be responsible for giving male fish female parts. Transgender fish haven’t turned up in local waters yet, but in Morro Bay the same chemical is suspected of causing goby fish to grow pale, vein-coursed liver tumors.

Local biologists can’t be certain there’s a connection, but they are suspicious. Last spring, Cal Poly biologist Lars Tomanek, along with others from Cal Poly and the Central Coast Regional Water Quality Control Board, went to investigate what chemicals might be leaching into local waters. They tested gobies because they’re bottom dwellers and a good indication of what’s in the sediment.

Tomanek said some of the gobies looked pregnant—they weren’t. The group soon found that the gobies, and particularly their tumors, were riddled with nonylphenol.

“That’s all we found,” Tomanek said. “And we’re like, OK, what the heck is that?”

He estimated about 10 percent of the fish they found had tumors.

Nonylphenol is a degraded form of the chemical nonylphenol ethoxylate. That chemical helps break down other compounds, which makes it useful in products such as detergents. But when the chemical goes through sewage treatment it breaks down to the more hazardous nonylphenol form.

Such chemicals as nonylphenol have some environmentalists concerned because they often slip through sewage treatment and end up in the ground and water. Sewage sludge, the solid byproduct, and septic tanks are big contributors of nonylphenol. County officials have banned sludge application to local lands, but that ban will expire in a year. A new ordinance that would allow some land application is working through the approval process, but some environmentalists have raised questions over how the ordinance would prevent chemicals and heavy metals from being leached.

For gobies, nonylphenol is like a hormonal guessing game. It’s chemically similar to goby estrogen and, when introduced into males, has been shown to lead to the development of female anatomy, including eggs.

Whatever is going on, it doesn’t appear that Morro Bay is the only place it is happening. Tomanek said he found nonylphenol in Tomales Bay and the gobies that live there. At this point, “We are basically trying to find gobies that don’t have [tumors and nonylphenol] and we don’t know where that’s going to be.”

The next testing ground will likely be farther north—probably along the Oregon coast—and those studies will begin in a couple of months.

Members of the Southern California Coastal Water Research Project are also taking a look at pollutants that seep into California waterways. They found nonylphenol, too.

Steven Bay, who heads the project’s toxicology department, said they have found nonylphenol along with a cocktail of other contaminants. Project researchers also found fish with some signs of gender-switching, he added.

Like here, the suspected source of the contaminants in Southern California is treated sewage discharge. Bay said the whole field of analyzing chemicals is still new territory; the tools and methods they use are only about a decade old. For now, the challenge is to sift through thousands of chemicals to find the really nasty ones.

“The information we don’t have right now is how to prioritize which of these chemicals are of the greatest concern,” Bay said.

But others have already labeled nonylphenol a big concern. The European Union effectively banned the chemical in nearly all uses. Canada officially classified nonylphenol as a toxic chemical and severely restricted the levels allowed in waterways.

It’s a different story in the U.S., where the allowable levels of nonylphenol are about twice those of Canada.

Members of the Sierra Club tried to change that, but have so far been unsuccessful. In 2007, they petitioned the federal Environmental Protection Agency to limit the use of nonylphenol because of its potential dangers. A Sierra Club paper on nonylphenol also points out that there are alternatives to the chemical that come with minimal cost increases. Ed Hopkins, who worked extensively to lobby for nonylphenol restrictions, said efforts to limit or ban the chemical were stymied by a combination of outdated policies, the Bush administration, and the political clout of big industry.

“I think it’s just a good chemical to illustrate how far behind the United States is in properly protecting the 
public …,” Hopkins said.

The Sierra Club is still in the middle of a lawsuit with the EPA.

The tricky part about nonylphenol is that despite its correlation to hermaphroditic fish and tumors, few seem willing to declare there’s a definitive link.

Tomanek and another Cal Poly biologist, Dean Wendt, were reluctant to say there is a cause-and-effect relationship. Instead, they say there is a correlation between nonylphenol and tumors.

Still, if their suspicions are correct, researchers from Cal Poly and the regional water board could be helping lay the foundations for a U.S. nonylphenol ban.

The research Tomanek is doing right now isn’t unheard of, he admitted. “But the extent and the levels [of nonylphenol] we’re finding, that seems to be ground-breaking.”

So what’s next?

There’s little question that nonylphenol is common in coastal waters. The key for Tomanek and others will be to show whether the chemical is hazardous in the amounts allowed under U.S. law.

Morro Bay looks to be a kind of Petri dish to answer that question. Local scientists will track the food chain to see if other species, such as larger fish 
or even sea otters, have nonylphenol in their bodies.

Even in these early testing stages, it doesn’t look like there’s a direct threat to humans. Tomanek noted that gobies aren’t a common menu item. Even if the chemical is making its way into other more edible fish, fish livers generally aren’t eaten. As for the spermicides, they’re safe, unless you’re a fish. ∆

Staff writer Colin Rigley believes that fish have a right to change genders. Send comments to


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