Sean Richards

Possible Side Effects

By Gary Hengstler

Ever wondered how those Tylenol tablets taken for the occasional headache will eventually affect some fish?


Well, Sean Richards has. He is a professor of biology, geology and environmental science at UT Chattanooga. In fact, he has studied how pharmaceuticals in streams affected the aquatic environment for the past 17 years.

He and his class examined effects associated with combinations of 13 pharmaceuticals, but isolating one specific product such as Tylenol isn’t the issue.  “It is the combination effect that is of concern,” he explains. “Yes, we have seen effects on reproduction of the Daphnia magna (a small white aquatic vertebrae commonly called the water flea) but not at environmentally relevant concentrations. But it is much more complicated than that.
“Lab tests cannot account for all of the stressors the organisms see.  It is very difficult to conclude no effects in the environment; plus, what about the other hundreds of drugs in the water?”

But pharmaceuticals are not the full range of his research. Richards, along with Steve Symes in the chemistry department, is currently assessing copper and lead and the water quality in 79 schools in Hamilton County (in the wake of the Flint Michigan water crisis).

Still, he primarily focuses on monitoring the increasing amount of pharmaceuticals in rivers and streams. Because treatment plants do not have filters to block drugs, the pharmaceuticals pretty much go into the surface waters, still retaining the powerful ingredients after humans expel them.

More pharmaceuticals are found in water than pesticides, says Richards. “However, pharmaceuticals receive far less attention because they are, by and large, agents of good (for humans). We don’t see them as poisons, but in fact, they are a very large input into the ecosystem.”

The drugs enter the water supply mainly through wastewater treatment plants because the plants do not filter out water-soluble molecules.

“This includes everything from caffeine to Prozac to Lipitor and even illicit drugs,” he says. “Things like Ciprofloxacin, an antibiotic, can go through the human body and be excreted largely unchanged. It still has its anti-microbial properties as it enters the sewage treatment plant, and we’re then finding it in surface waters.”

Richards cites a two-year study where they took 220 water samples from Knoxville to Chattanooga. When they analyzed the samples, they found caffeine 95 percent of the time. They also found Ciprofloxacin and Prozac.

Now he is analyzing the findings to discover how these drugs may harm the aquatic invertebrates—like the water flea.
“We were interested in (this species) because they are the base of the food chain,” he says. “I have students in my lab testing for pharmaceuticals in various combinations and concentrations to determine what kind of ecological effects they have.”

Physicians warn patients not to take some drugs with other prescribed medications (called contra-indicated when a drug by itself serves a purpose but, when taken at the same time with another sole-purpose drug, the combination can have serious negative consequences). Richards also is looking at this issue with respect to aquatic life.

“We’ve been doing testing on organisms to see if combinations of these contra-indicated drugs cause greater effect than when they are in concentration alone,” he says. “But there are about 25,000 pharmaceuticals out there with about 3,000 different modes of action.”

He stresses that many pharmaceuticals have ibuprofen, so his tests only focus on the active ingredient—out of 3,000. “Trying to look at all various combinations of 3,000 different modes is pretty tough,” he says.

Richards says that one of his biggest concerns is that the molecules are built to have a physiological effect in humans, “but fish and plants and aquatic invertebrates have a different physiology than humans. So, what effects are being seen in those organisms? It can be very subtle to where we might not even notice.”

He points to his research in Canada where artificial ponds contain everything from bacteria to fish and plants. “We would dose those ponds with various concentrations of Prozac, and we saw the fish with the really high doses were visually affected,” he says. “They were a lot more lethargic, not as quick to escape the nets when we tried to catch them.”

Richards foresees that, with an aging population and the increasing reliance on pharmaceuticals, the potentially harmful impacts on the ecology also will rise.

“Again, is not only the volume; it’s the combination of these factors,” he says. “In a lot of places where we are drawing water out (as with other types of pollution), you’re increasing the concentration of the pharmaceuticals. We are not seeing fish die from this, but we are affecting their behavior and development.

He also notes that some studies have found trace amounts of pharmaceuticals in the public’s drinking water.

“We would not give 99.9 percent of these pharmaceuticals to a 3-month-old baby, but all these juvenile fish and frogs and turtles and everything else in the aquatic world are being exposed to these and raised in these drugs.

What we are trying to do now is to see if there is a multi-generational effect—if the parents are exposed and the offspring are exposed and then their offspring are exposed, are they becoming more or less sensitive to these pollutants?”

Scientists can show specific instances of adverse effect on wildlife aquatic, but Richards says the problem is finding the smoking gun.

“With any type of mixture of toxicology or mixture of toxicity, the difficulty is to show that this combination of three pharmaceuticals is causing this absolute effect—too many variables. We see that even with pesticides into the landscape. Assigning blame to a specific compound is really tough unless it is really overt.”

This, he notes, is exacerbated with pharmaceuticals because the medications are meant to do nothing but help our population.

And here science, government and economics collide anew.

New sewage treatment plants with a charcoal filtration system could remove the pharmaceuticals.

“But people generally don’t even want to spend for traditional sewage treatment plants just take out the basics. So, to spend funds now to remove pharmaceuticals is not something that will be popular. People are not going to be elected by saying they will build a new sewage treatment plant to take out every single component.”

With organisms stressed by pesticides, nutrient loading and increased temperatures, he says, “You might not be able to show that one pharmaceutical is having significant population effects, but I don’t think anyone would deny that all these together are going to affect the ecosystem. We just don’t know in what way and how severe.”