Frogs And Fish Mix With Pharmaceuticals In Water, Results Aren’t Pretty
By Robin Grant
Science Reporting Class, Carleton University School of Journalism
Fish and frogs aren’t cute and cuddly. They aren’t even the often-thought-of test subjects in scientific experiments. But that doesn’t deter University of Ottawa’s Research Chair in Neuroendocrinology, Dr. Vance Trudeau, who studies the animals’ reproductive system – or lately – both animals’ lack of reproduction.
In fact, fish and frogs play the key role in Trudeau’s award-winning research in the emerging field of endocrine disruption – the science of how pollutants affect the hormone system in animals, including humans.
Endocrine disruption was not coined as a science until the ‘80s. But the public first learned about the phenomena in the 1950s with the pesticide called DDT.
One of the chemical’s most infamous affects on animals was seen in the eggshells of predatory birds. After coming into prolonged contact with the chemicals, birds like the bald eagle, the peregrine falcon and the brown pelican could not lay a shell thick enough for it to sit on and hatch the chick.
While DDT is still used in controlled circumstances today, mainly to combat malaria in developing countries, the public outcry on the effect the pesticide had on wildlife resulted in its discontinued used in many countries, including the Canada and the United States.
Today, Trudeau’s research in endocrine disruption focuses specifically on how pharmaceutical pollutants in water effect fish and frogs.
Fish are important in his study, because being purely aquatic animals, they are completely dependent on water. This means they can’t escape pollutant-saturated water, and absorb the chemicals into their bodies.
“Fish can’t avoid pollutants. So they’re are like a monitor. They take up pollutants. They can metabolize some, but they keep others. And they’re really heavily affected,” Trudeau says.
One of Trudeau’s most significant experiments used goldfish to look at how the common antidepressant Prozac, found in mass amounts in human drinking water, inhibited the animal’s sexual activity.
Published in the journal Aquatic Toxicology in 2010, the study found that male goldfish exposed to water treated with Prozac experienced a 50 per cent decrease in sperm production.
The research tested fish in two levels of treated water for week-long periods. Water type one had the same levels of Prozac found in sewage effluent. The other level had an even higher Prozac concentration. In both levels, the male fish didn’t respond when the females released the chemical pheromones. In a natural environment, the female’s natural bodily function should have induce the males to produce sperm.
Trudeau is interested in frogs for two reasons. One reason is because there is a worldwide species decline, and he has conducted a study that helps a certain species of frog reproduce in captivity. And two, because the tadpole, as a scientific model, closely resembles the human embryo.
“Frogs are interesting because most are aquatic at the tadpole stage. The tadpole stage is like an embryo. It’s like studying the human embryo, but it’s easier. And that’s the most sensitive phase of life.”
According to Trudeau, because the tadpole is so sensitive it reacts to powerful pharmaceutical pollutants, like estrogen-based, oral contraceptives found in drinking water. With a hormonal system similar to humans, frogs are affected by the drugs in similar ways.
“The concentration of estrogen in the skin ends up affecting its sexual development. For example, male tadpoles retrain ovary cells in their testicles,” Trudeau says.
And while the public can’t seem to find an economic benefit in protecting frog species, Trudeau considers the species decline to be one of the foremost issues in environmental science, because of the key role the frogs play in the ecosystem.
“They play a very important role in the ecosystem. They eat bugs and other pests, which have caused problems in farming,” he says. “Other animals eat them; they are a food source for humans.”
In 2011, Trudeau used a hormone trick that made it possible to breed certain species of frog in captivity – a feat nearly impossible to do in some species.
“In that case, I adapted fish breeding techniques to leopard frogs, and it worked,” he says. The technique was later dubbed: “Vance’s Love Potion.”
So how are pharmaceuticals getting into the waterways and causing reproductive deficiencies in fish and frogs, which results in the worldwide decline of both species?
Trudeau says it happens because sewage treatment plants neglect to separate the chemicals, which contain hormones like estrogen, from the waste. The chemicals filter through the system, and are released back into lakes and rivers. And bacteria convert it back into a biologically active form, containing the original hormone.
“The sewage system is good for some things, but it was not designed for removing these chemicals,” he says.
Also, certain studies suggest we are entering a “vicious cycle” where the presence of pharmaceuticals in aquatic animals results in their re-ingestion by humans, which could cause damages to human fetuses.
And Trudeau agrees.
“If [the chemicals] get into the drinking water and the fish, for example, some of these chemicals cause harmful defects in humans,” he says.
Trudeau points to two main ways to address the problem. The first is that people need to ask their doctor if the drug they are prescribed is really necessary. The second is to improve the purification systems.
Canada has a cooperative network, which includes the University of Ottawa, that is developing technologies that eliminate certain pharmaceuticals in purification plants.
“Upgrading sewage treatment plants will be expensive, but in the long run, it is necessary and effective,” Trudeau concludes.
Ultimately, Trudeau hopes his work will contribute to helping two aquatic creatures that are defenseless against human-caused pollutants. Not only that, because both animals are so integral to to the food chain, their disappearance would be an ecological disaster. So, in the end, his science just might help humans, too.