MONTREAL - St. Lawrence River fish are loaded with Prozac and other antidepressant drugs, leading scientists to wonder if the "happy hormone" is altering the lifestyle of the chronically grumpy-looking marine animals.
Researchers at the Université de Montréal and Environment Canada have discovered large quantities of antidepressants in the liver, muscle and brain tissues of brook trout exposed to three months of various levels of treated effluent from Montreal's sewage treatment plant.
According to the peer-reviewed study, published this week in the journal Chemosphere, most of the drug was found in liver tissue. Slightly less was found in the brain. The least amount was found in muscle, which is the filet eaten by humans.
U de M professor Sébastien Sauvé, a co-author of the study, said that because relatively small amounts are found in meat tissue, he is not worried that these fish pose a danger to humans.
Research during the last two decades has revealed that pharmaceutical drugs and personal care products are a major source of pollution in the marine environment. Even in very low concentrations, they have altered the ecosystems.
Sauvé said such drugs as chemotherapy medicines, hormones and antibiotics have been found in fish and pose a greater danger to human health than antidepressants.
"My real concern is the effects on the fish," he said, adding they "could be quite serious."
He said the study shows that fish exposed to the effluent have changes in their brains's nerve activity. "We don't know if these are positive or not."
The problem is how to measure behavioural changes in fish.
"It's very hard," Sauvé said. "The question itself is quite interesting. You can't ask a fish whether it is happier or not.
"One of things they can do is use cameras to look at the male behaviour. Will it have the same behaviour in mating or feeding? Then you have to go back and look at its normal behaviour. It's quite tedious work and difficult."
Quebecers purchase about 555 million anti-depressants a year from pharmacies. That works out to about one in four Quebecers taking one pill a day. That does not include the amount prescribed by psychiatric hospitals.
Residue from antidepressants leaves the body and ends up in our waterways. Sauvé said his study indicates the problem of antidepressants contaminating marine animals is probably global.
Most treatment plants are not equipped to deal with pharmaceuticals. Montreal's sewage treatment plant treats only solids and does not remove chemicals.
"The chemical structure of antidepressants makes them extremely difficult to remove from sewage, even with the most sophisticate systems available," Sauvé said.
Montreal is experimenting with ozone treatment, which, according to the study, reduces the level of antidepressants in the effluent leaving the plant, but does not eliminate them.
The research team found eight kinds of anti-depressants in the fish. The highest concentrations came from Prozac.
The study is a result of a controlled experiment. How much antidepressant medication is in fish in the river will vary greatly, depending on the kind of fish and its habitat.
BY WILLIAM MARSDEN
JANUARY 21, 2011