Fish on Prozac: Anxious, anti-social, aggressive (Page 2)
|Waleed Alzuhair/flickr |
(Continued from Page 1)
June 12, 2013
When monitoring an Iowa and a Colorado stream, the U.S. Geological Survey found most drugs at levels similar to Los Angeles County’s. However, these low levels could still find their way into fish brains, according to their 2010 study.
Researchers found elevated levels of pharmaceuticals in the stream water two to six miles from the sewage treatment plants. But the chemicals at the highest levels in the water were not the ones most prevalent in the fish brains.
“The fish downstream of the wastewater treatment had elevated concentrations of two antidepressants … Zoloft and Prozac,” said Edward Furlong, a research chemist at the U.S. Geological Survey based in Boulder, Colo. “And these were relatively low in water compared to others.”
Even if the levels released into streams seem low, they are constant, which is problematic, Brooks said.
“The drugs may not be classically persistent like PCBs,” Brooks said. “But they’re pseudo-persistent. The [continuous] exposure of organisms in a stream is equivalent to a chemical that is persistent.”
Some drugs bioaccumulate, or build up, in rainbow trout, according to Brooks’ research. Also, rainbow trout exposed to sewage effluent have pharmaceuticals in their blood at levels as high as those that affect the brains of people, according to research in Sweden.
Brooks said the likelihood of bioaccumulation for pharmaceuticals is high. “People have to take these drugs for weeks before they start having effects. They slowly bioaccumulate in your system,” which suggests bioaccumulation potential in fish, too, Brooks said.
Changes to the brain can affect all kinds of things in fish, Klaper said. And since humans have a similar brain gene structure, the findings raise questions about whether traces of these drugs in drinking water might harm human health.
The U.S. Environmental Protection Agency considers pharmaceuticals an “emerging concern,” and has concluded that the chemicals may pose risks to wildlife and humans. There are currently no federal regulations of the compounds in waste or drinking water. However, 12 pharmaceuticals are currently on the EPA’s Contaminant Candidate List, which are chemicals that may require regulation under the Safe Drinking Water Act.
Studies have consistently found prescription drugs in drinking water at parts-per-trillion levels. U.S. Geological Survey scientists sampled 74 waterways used for drinking water in 25 states in 2008 and found 53 had one or more of the three dozen pharmaceuticals they were testing for in their water. Forty percent of the pharmaceuticals were found at one or more of the sites.
But health officials say the levels found in some drinking water are too low to cause harm.
According to a 2012 World Health Organization report, the “trace quantities of pharmaceuticals in drinking water are very unlikely to pose risks to human health.” The report said that the amount found in drinking water is usually 1,000 times lower than doses expected to have an effect on a person.
But Klaper said that in light of the gene changes in fish brains, officials may need to rethink what is considered safe.
“Fish do not metabolize drugs like we do,” Klaper said. “Even if environmental doses aren’t thought to be much for a human, fish could still have significant accumulation, and, it appears, changes in their brain’s gene expression.”
The above work, by Environmental Health News, is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
Recent Environmental Health News coverage