tx H2O

txH2O Winter 2010

This is your stream. This is your stream on drugs.

Scientists' expanding research and technologies show that traces of pharmaceuticals in water may threaten aquatic health

All over Texas, humans and animals are using pharmaceuticals: psychiatrists prescribe anti-depressants, veterinarians give farm animals hormones and antibiotics, and patients recovered from surgery flush their expired prescription pain-killers. In each case, traces of these drugs and other pharmachemical compounds can make their way through wastewater treatment facilities and eventually into natural water ways that supply drinking water for humans, livestock, and wildlife, as well as habitats for aquatic species.

Dr. Chu

Dr. Chu testing chemicals. Photo by Leslie Jordan

As scientists and engineers learn more about this problem, work to detect more contaminants, and develop solutions for keeping water safe, should consumers be worried about effects these substances could have on public health? According to the current body of research, the answer is no. Should they be concerned about the impact on the fish, turtles, and aquatic life in those waterbodies? Maybe so.

From obscurity to controversy

After a decade of researching pharmaceuticals and personal care products (PPCPs) in water and treated wastewater, Dr. Bryan Brooks, professor of environmental science and biomedical studies at Baylor University, has seen the interest in the subject grow exponentially. Brooks recalls earlier days when he and colleague Dr. Kevin Chambliss, a Baylor chemistry professor, were among the few researchers studying this topic-compared to thousands of papers and projects focusing on PPCPs today.

One reason for this increased attention is that researchers' ability to detect and measure PPCPs in water has grown. Because scientists are continually learning how to identify more and more substances at lower and lower levels, increasing numbers of reports have resulted in a growing public awareness of PPCPs in water.

In 2008, the Associated Press released an extensive report on pharmaceuticals in drinking water that included statistics on levels of these drugs in municipal water supplies throughout the country. The report brought this emerging water issue to the attention of the public and congressional legislators.

According to Brooks, although the prospect of leftover pharmaceuticals in your water glass may sound troublesome, the facts show that when chemical compounds from pharmaceuticals are found in water supplies, they generally exist in miniscule amounts-on the scale of low or sub-parts per trillion.

"If you were to look at parts per trillion, or 50 nanograms per liter, of a pharmaceutical, that's like 50 people being surrounded in a field by a trillion of their closest friends-so not that many-and that's a higher number than what is detected in drinking water," Brooks said.

"The science is developing rapidly," he said. "We need to now step back, think about lessons learned in managing water quality and substances in the environment, and then ask the most relevant questions, so that we are managing real risks and not just those that we think may be a problem."

Drugs in Texas waters

In 2006, Brooks and Chambliss studied fish in Pecan Creek in Denton, and found residues of three human medications not previously identified in fish tissue. These three new compounds were from an over-the-counter antihistamine, a drug for high blood pressure, and a treatment for epilepsy and bipolar disorder. Researchers also found an antidepressant that had been detected in a previous study. Like many waterways in Texas, Pecan Creek receives treated effluent from a wastewater treatment plant.

"These results demonstrated the increasing need to consider bioaccumulation of emerging contaminants in the environment," Chambliss said. "This research proved that fish are being exposed to multiple compounds in our waterways."

Chambliss and doctoral student Alejandro Ramirez developed a method of using liquid chromatography-tandem mass spectrometry that enabled them to, for the first time, simultaneously screen the fish for several different types of drugs. Previous PPCP studies could only identify individual medications or classes of medications, but the Baylor team's new method tested for up to 25 different drugs in several therapeutic categories.

The researchers concluded that while the results showed the potential dangers for fish and other aquatic life, the risk to human public health was minimal but should be monitored.

"The pharmaceutical levels that are detected in drinking water supplies and in edible fish species' tissue are far below the normal daily dosage someone would take of that medicine. So yes, we need to study the issue, but right now the highest relative risk is not to people," Brooks said. "By looking at therapeutic thresholds for drugs, we see that these risks are much lower than others we experience in life, such as driving to work. But there are risks for the organisms living in these streams, experiencing exposure to these substances-which in fact in some cases has shown adverse effects in aquatic organisms."

By combining risk assessment and toxicology, Brooks uses existing pharmacology and toxicology information about how drugs affect humans to more efficiently predict their potential effects on wildlife.

"I'm working to see how we can use existing toxicology information on pharmaceuticals and comparative biology data to identify which types of compounds are most risky to wildlife," he said. "We don't have hundreds of millions of dollars to spare, so why reinvent the wheel? If we can use existing information, based on pharmacology in humans, we have shown that you can actually use that information to predict potential compounds of concern for wildlife. I think it's a prudent approach."

The threat to aquatic life

The dangers that PPCPs pose for aquatic life merit additional research because when fish live in streams containing PPCPs, they are exposed to a veritable buffet of chemical compounds, which were designed for specific purposes and doses. These compounds were not designed for an organism's entire life or for usage in combination with other compounds, Brooks said.

"Most medications are not intended to be used for the whole life-cycle of an organism. They are meant to be used for days, weeks, perhaps months, and sometimes longer," he said.

Brooks and Chambliss recently proved that fish throughout the country are exposed to multiple PPCPs. In 2006, the researchers were contracted to conduct an U.S. Environmental Protection Agency (EPA) pilot study because of their innovative methodologies for detecting PPCPs in fish tissue. The study, the first designed to look for the occurrence of PPCPs in fish from U.S. waterways, specifically focused on effluentdominated rivers.

The sampling locations included discharge areas of wastewater treatment plants in Chicago, Dallas, Orlando, Fla., Phoenix, and West Chester, Pa., near Philadelphia. Isolated from human sources of contamination, the Gila River Wilderness Area in New Mexico was the study's reference site.

The researchers tested fish fillets and liver tissue for 24 different human medications, and tested fish fillets for 12 chemicals found in personal care products. The results revealed that the residues of seven pharmaceuticals and two personal care products were in fish at all five sampling locations. Multiple compounds were often found in the same fish. Gemfibrozil, a medication used to treat high cholesterol and triglyceride levels, was found in livers of wild fish for the first time. No pharmaceutical compounds or personal care product chemicals were detected in any fish collected at the reference stream in New Mexico.

"While this study found the residue of several pharmaceuticals and personal care products in fish tissue, it also demonstrated for the first time that fish from several different locations across the country are exposed to multiple PPCPs in effluent-dominated waterways," Brooks said.

Because of Brooks and Chambliss's findings, the EPA expanded its investigation of PPCPs in fish under its National Rivers and Streams Assessment. This project completed fish collection in 2009 and will release a final report in 2011.

Engineering beneficial bacteria

Environmental engineers also are looking at the problems PPCPs pose to drinking water, and are developing innovative techniques to remove the contaminants.

Dr. Kung-Hu "Bella" Chu, assistant professor of environmental engineering in the Zachry Department of Civil Engineering at Texas A&M University, has been studying organic compounds in water and wastewater since 2002. She has successfully identified and isolated bacteria to biodegrade estrogenic compounds frequently found in treated wastewater.

Environmental estrogens in wastewater are a result of synthetic estrogens in pharmaceuticals such as birth control and hormone therapies, as well as natural estrogens excreted by humans and animals-both male and female. Estrogenic compounds enter into the environment via effluent because wastewater treatment facilities are not designed to remove them. As with non-estrogenic PPCPs, the dangers estrogen residues pose to fish and wildlife are more widely accepted than potential threats to human health.

In 2006, Chu and her postdoctoral researcher, Dr. Chang- Ping Yu, and doctoral student Hyungkeun Roh discovered a bacteria strain called strain KC8 that efficiently degraded estrogens in wastewater.

Roh then worked to further characterize the strain, which included testing how various environmental factors affected its estrogen degradation ability.

"The good news is that in the real world, this strain can grow fast because it can use the various organics readily available in the wastewater," Chu said. "This strain can use estrogen to grow, too-it's kind of their food, so that they can reproduce. But other microorganisms can also degrade estrogen, just differently.

"One group of important wastewater microorganisms, ammonia-oxidizing bacteria, cannot grow on estrogens, but rather they can degrade estrogens just for fun-it's like candy for them!"

Chu and her research team are continuing to study these various organisms, including the different ways they degrade estrogens and the best environmental conditions for the degradation.

"For example, strain KC8 grows really fast in an organic-rich environment, but ammonia-oxidizing bacteria grow really slowly and take a longer time, probably double, in that environment," Chu said. "So we need to ask, what conditions and which microorganism might play a significant role in degrading these estrogens?"

From pristine streams to hormonal rivers

Another concern that Chu wants to address is the many other trace organics with estrogenic potential found in wastewater. Individually, these substances are present at relatively low concentrations, but together they might trigger unwanted estrogenic responses.

To investigate this, Chu and her team used a Yeast Screening Assay, which can look for the estrogenic potential of a specific compound or a mixture of chemicals. The assay produces a red color to indicate the presence of estrogenic compounds in the tested samples.

"So it's going to tell you if the compounds-both known and unknown compounds in the water-would induce any biological response, rather than tell you the concentration of an individual compound measured by chemical analysis," Chu said. "This assay is complementary to chemical analysis since it helps with deciding if a biological response will be triggered or not."

The assay was used in a study Chu conducted in Tennessee's Great Smokey Mountains National Park, where her team took water samples along a river that flows through the park.

"We used this pristine area, with the high elevation water," Chu said. "But right after you get out of the park gate, probably 10-15 miles down, the area is very developed."

Due to tourism, the population around the river fluctuates, and several wastewater treatment facilities are needed in the community. The small river is clean as it flows through the park, but outside of the park, the treated wastewater from the plants discharges into the river. The researchers took samples at several different points-at the border of the park, along the river, near the wastewater treatments plants, and then downstream of the plants.

"In this short study, we first demonstrated the impact-that yes, treated wastewater is contributing estrogenic compounds into the receiving water body," Chu said. "And then we also wanted to know, how long would it take for these concerning compounds to be naturally attenuated in the river water before it is used as a drinking water source?"

According to Chu, her team found that the estrogenic responses in the river water decreased as the river flowed away from the effluent outfalls, but elevated estrogenic responses were still observed in the river about a mile and a half away from the discharge points. Chu said that this suggested the river may not be able to remove some chemicals naturally or fast enough.

"Continuous discharge of these compounds into the receiving waters, like effluent containing estrogen, can serve as a long-term pollution source in the river," she said. "Despite the capacity of natural purification, these chemicals will remain in the river to potentially cause harm to aquatic life and require advanced treatment processes to remove these compounds. From a sustainability point of view, we need to find a cost-effective treatment approach to remove these chemicals from wastewater to minimize the release of these compounds into the environment."

Looking ahead

As Americans continue consuming pharmaceuticals, scientists keep researching PPCPs in water, and as wastewater treatment technologies advance, the science and the public's response to these issues are sure to evolve.

"Water is something that we must have, clearly, and all great civilizations have flourished when there were plentiful supplies of high-quality water," Brooks said. "So our situation is no different from lessons that we have learned throughout history. Responsible water management is trying to understand emerging issues, and make responsible decisions for the environment, our drinking water, and our fisheries."

As scientists continue to examine the pharmaceutical problem, state and federal agencies are developing innovative policy and monitoring solutions.

To flush or not to flush

The Texas Commission on Environmental Quality (TCEQ) is looking at better standardizing how pharmaceutical compounds get into the environment in the first place. Texas Senate Bill 1757, which became effective in June 2009, commissioned TCEQ to conduct a study of methods for disposing of unused pharmaceuticals so that they do not enter a wastewater system. By January 2011, TCEQ is required to submit to the legislature a report on the best methods for disposal.

Identifying emerging contaminants

Every five years, the U.S. EPA releases a Contaminant Candidate List (CCL). The CCL 3 list was completed in 2009. The list identifies emerging contaminants and currently includes several PPCPs. According to EPA, it considered the best available data and information on health effects and occurrence to evaluate thousands of unregulated contaminants. The resulting list includes pesticides, disinfection byproducts, chemicals used in commerce, waterborne pathogens, pharmaceuticals, and biological toxins. EPA will evaluate all the contaminants on the CCL 3 to determine which have sufficient information to allow EPA to make a regulatory determination, and which contaminants need to be further researched to determine regulatory actions. To learn more, see EPA's Web site.

*Some information from Baylor University News.

Back to Top