Scientists are concerned by the increasing variety of contaminants in the environment. Traces of pesticides and caffeine were found in the Zumbro River, above, in Minnesota.Credit Brent Frazee/Kansas City Star, via MCT, via Getty Images Deborah Swackhamer, a professor of environmental health sciences at the University of Minnesota, decided last year to investigate the chemistry of the nearby Zumbro River. She and her colleagues were not surprised to find traces of pesticides in the water.
Neither were they shocked to find prescription drugs ranging from antibiotics to the anti–convulsive carbamazepine. Researchers realized more than 15 years ago that pharmaceuticals – excreted by users, dumped down drains – were slipping through wastewater treatment systems.
But though she is a leading expert in so-called emerging contaminants, Dr. Swackhamer was both surprised and dismayed by the sheer range and variety of what she found. Caffeine drifted through the river water, testament to local consumption of everything from coffee to energy drinks. There were relatively high levels of acetaminophen, the over-the-counter painkiller. Acetaminophen causes liver damage in humans at high doses; no one knows what it does to fish.
“We don’t know what these background levels mean in terms of environmental or public health,” she said. “It’s definitely another thing that we’re going to be looking at.”
Or, she might have said, one of many, many other things. The number of chemicals contaminating our environment is growing at exponential rate, scientists say.
A team of researchers at the U.S. Geological Survey tracks them in American waterways, sediments, landfills and municipal sewage sludge, which is often converted into agricultural fertilizer. They’ve found steroid hormones and the antibacterial agent triclosan in sewage; the antidepressant fluoxetine (Prozac) in fish; and compounds from both birth control pills and detergents in the thin, slimy layer that forms over stones in streams.
“We’re looking at an increasingly diverse array of organic and inorganic chemicals that may have ecosystem health effects,” said Edward Furlong, a research chemist with the U.S.G.S. office in Denver and one of the first scientists to track the spread of pharmaceutical compounds in the nation’s waterways. “Many of them are understudied and unrecognized.”
In an essay last week in the journal Environmental Science & Technology, titled “Re-Emergence of Emerging Contaminants,” editor-in-chief Jerald L. Schnoor called attention to both the startling growth of newly registered chemical compounds and our inadequate understanding of older ones.
The American Chemical Society, the publisher of the journal, maintains the most comprehensive national database of commercially registered chemical compounds in the country. “The growth of the list is eye-popping, with approximately 15,000 new chemicals and biological sequences registered every day,” Dr. Schnoor wrote.
Not all of those are currently in use, he emphasized, and the majority are unlikely to be dangerous. “But, for better or worse, our commerce is producing innovative, challenging new compounds,” he wrote.
Dr. Schnoor, a professor of civil and environmental engineering at the University of Iowa, also noted rising concern among researchers about the way older compounds are altered in the environment, sometimes taking new and more dangerous forms.
Some research suggests that polychlorinated biphenyls, or PCBs, are broken down by plants into even more toxic metabolites. Equally troubling, scientists are finding that while PCBs are banned, they continue to seep into the environment in unexpected ways, such as from impurities in the caulk of old school buildings.
PCBs have long been identified as hazardous, but not every contaminant is so risky, Dr. Schnoor emphasized.
“Out of the millions of chemical compounds that we know about, thousands have been tested and there are very few that show important health effects,” he said in an interview.
But, he added, the development of new compounds and the increasing discovery of unexpected contaminants in the environment means that the nation desperately needs a better system for assessing and prioritizing chemical exposures. That includes revisiting the country’s antiquated chemical regulation and assessment regulations.
The Toxic Substances Control Act went into effect in 1976, almost 40 years ago, and has not been updated since. The law does require the Environmental Protection Agency to maintain an inventory of registered industrial compounds that may be toxic, but it does not require advance safety testing of those materials. Of the some 84,000 compounds registered, only a fraction have ever been fully tested for health effects on humans. The data gap includes some materials, like creosote and coal tar derivatives, which are currently manufactured at rates topping a million pounds a year.
Not surprisingly, Dr. Schnoor and other scientists want to see the act updated and transformed into a mechanism for science-based risk assessment of suspect compounds. Indeed, everyone from researchers to environmental groups to the American chemical industry agree that the law is frustratingly inadequate. “Our chemical safety net is more hole than net,” said Ken Cook, president of the Environmental Working Group, an advocacy group. The Food and Drug Administration, for instance, doesn’t regulate the environmental spread of pharmaceuticals. And the toxic substances law ignores their presence in waterways. “Where does that leave us in terms of scientific understanding of what drugs to regulate?” Mr. Cook said.
Anne Womack Kolton, vice president for communications at the American Chemistry Council, an organization representing chemical manufacturers, agreed. “Think about the world 40 years ago,” she said. “It was a vastly different place. It’s common sense to revise the law and make it consistent with what we know about chemicals today.” The two sides don’t agree on what standards for chemical testing are needed or what kind of protective restrictions should be put in place for chemicals deemed hazardous. And they are in deep disagreement about whether a revised federal law should preempt actions taken by tough-minded states like California. The council argues for federal standardization as the most efficient route; environmental groups believe that such an action would weaken public protection. Legislators have so far not been able to resolve those differences.
This month yet another proposed update to the act stalled in a Senate committee. “Congress has not sent an environmental law to the president’s desk in 18 years,” Mr. Cook said. “And in the current environment, it’s very difficult to get something through.”
Still, Dr. Swackhamer, who recently stepped down as chair of the E.P.A.’s science advisory board, notes that despite the lack of legislation, scientists have been working toward better ways to assess the risks posed by the increasing numbers of chemicals in our lives. Some may help whittle the inventory of T.S.C.A. compounds down to a priority list that focuses on less than a thousand products. That’s still a daunting number of chemical unknowns. But given the tens of thousands of materials in the inventory, it’s a start.
A version of this article appears in print on 09/30/2014, on page D3 of the NewYork edition with the headline: An Ecosystem Mystery: What Is It?.