From: Andy Soos, ENN
Published April 1, 2013 09:24 AM
Pharmaceuticals in Streams
Pharmaceuticals commonly found in the environment are found in
streams, with unknown impacts on aquatic life and water quality. So
reports a new Ecological Applications paper, which highlights the
ecological cost of pharmaceutical waste and the need for more research
into environmental impacts. Pharmaceuticals, or prescription and
over-the-counter medications made for human use or veterinary or
agribusiness purposes, are found often in the environment.
Antibiotics,vitamins, supplements, and sexual enhancement drugs are
contained in this group. These products typically enter the environment
when passed through the body and then entering into the ground or sewer
lines, or when disposed of in the trash, septic tank, or sewage system.
A study by the U.S. Geological Survey report published in 2002 found
detectable quantities of pharmaceuticals in 80 percent of a sampling of
139 susceptible streams in 30 states. The most common pharmaceuticals
detected were steroids and nonprescription drugs. A 2006 study found
detectable concentrations of 28 pharmaceutical compounds in sewage
treatment plant effluents, surface water, and sediment. The therapeutic
classes included antibiotics, analgesics and anti-inflammatories, lipid
regulators, beta-blockers, anti-epileptics, and steroid hormones.
Although most chemical concentrations were detected at low levels
(nano-grams/Liter (ng/L)), there are uncertainties that remain regarding
the levels at which toxicity occurs and the risks of bioaccumulation of
these pharmaceutical compounds
Lead author Dr. Emma Rosi-Marshall in the new study, a scientist at the
Cary Institute of Ecosystem Studies, comments: "Pharmaceutical pollution
is now detected in waters throughout the world. Causes include aging
infrastructure, sewage overflows, and agricultural runoff. Even when
waste water makes it to sewage treatment facilities, they aren't
equipped to remove pharmaceuticals. As a result, our streams and rivers
are exposed to a cocktail of synthetic compounds, from stimulants and
antibiotics to analgesics and antihistamines."
With colleagues from Indiana University and Loyola University Chicago,
Rosi-Marshall looked at how six common pharmaceuticals influenced
similar-sized streams in New York, Maryland, and Indiana. Caffeine, the
antibiotic ciprofloxacin, the antidiabetic metformin, two antihistimines
used to treat heartburn (cimetidine and ranitidine), and one
antihistamine used to treat allergies (diphenhydramine) were
investigated.
Rosi-Marshall explains, "We focused on the response of biofilms — which
most people know as the slippery coating on stream rocks — because
they're vital to stream health. They might not look like much to the
naked eye, but biofilms are complex communities composed of algae,
fungi, and bacteria all living and working together. In streams,
biofilms contribute to water quality by recycling nutrients and organic
matter. They're also a major food source for invertebrates that, in
turn, feed larger animals like fish."
A biofilm is an aggregate of microorganisms in which cells adhere to
each other on a surface. These adherent cells are frequently embedded
within a self-produced matrix of extracellular polymeric substance.
Biofilm, which is also referred to as slime (although not everything
described as slime is a biofilm), is a polymeric conglomeration
generally composed of extracellular DNA, proteins, and polysaccharides.
Biofilms may form on living or non-living surfaces and can be prevalent
in natural, industrial and hospital settings.
Healthy streams are slippery streams. And it turns out that
antihistamines dry more than our noses. The most striking result of the
study was diphenhydramine's effects on algal production and microbial
respiration. Exposure caused biofilms to experience up to a 99% decrease
in photosynthesis, as well as significant drops in respiration.
Diphenhydramine also caused a change in the bacterial species present in
the biofilms, including an increase in a bacterial group known to
degrade toxic compounds and a reduction in a group that digests
compounds produced by plants and algae.
For further information see
Stream Pharmaceuticals.
Biofilm image via Wikipedia.
©2013. Copyright Environmental News Network To
subscribe or visit go to: http://www.enn.com
http://www.enn.com/pollution/article/45796
|