Pharmaceutical and illicit drugs are present
in streams in Baltimore, Maryland. At some sites, amphetamine concentrations
are high enough to alter the base of the aquatic food web.
So reports a new study released today in the
journal Environmental Science & Technology, which is one of the first to
explore the ecological consequences of stimulant pollution in urban streams.
Lead author Sylvia S. Lee conducted the work
as a postdoctoral researcher at the Cary Institute of Ecosystem Studies. Lee,
now with the Environmental Protection Agency, comments, "Around the world,
treated and untreated wastewater entering surface waters contains
pharmaceuticals and illicit drugs that originate from human consumption and
excretion, manufacturing processes, or improper disposal. We were interested in
revealing how amphetamine exposure influences the small plants and animals that
play a large role in regulating the health of streams."
Lee and her collaborators measured
concentrations of pharmaceutical and illicit drugs at six stream sites along an
urban-to-rural gradient in Baltimore, Maryland. Numerous drugs, including
amphetamine, were detected in stream sites, with illicit drug levels highest in
the most urban streams. Sampling was performed in 2013 and 2014. Suburban and
urban fieldwork focused on the Gwynns Falls watershed, which is part of the
Baltimore Ecosystem Study Long-Term Ecological Research program. The two rural
streams were located in Oregon Ridge watershed, the closest forested region.
Field sampling was then followed up with an
artificial stream experiment to determine how amphetamine - a biologically
active, highly addictive, and widely used drug - affects stream life. In recent
years, there has been an increase in the use of amphetamine medications in the
treatment of conditions like attention-deficit hyperactivity disorder. At the
same time, stimulants like methamphetamine, ecstasy, and cocaine are also used
Co-author Emma J. Rosi-Marshall, a freshwater
ecologist at the Cary Institute, comments, "We have every reason to
suspect that the release of stimulants to aquatic environments is on the rise
across the globe, yet little is known about the ecological consequences of this
pollution. We found that when artificial streams were exposed to amphetamine at
a concentration similar to what we found in parts of the Gwynns Falls
watershed, there were measurable and concerning effects to the base of the
aquatic food web."
After recreating natural stream attributes in
the Cary Institute's Artificial Stream Facility, four streams received a target
amphetamine concentration of 1 µg L-1 and four streams were maintained as controls.
Researchers monitored ecosystem effects over three weeks. Among their findings:
in streams with the amphetamine addition, the growth of biofilms was
significantly suppressed, the composition of bacterial and diatom communities
changed, and aquatic insects emerged earlier.
The field component of this study is one of
the first to report amphetamine in wastewater-impacted environments at
concentrations approaching 1 µg L-1. The laboratory component confirms that
amphetamine is present in the Gwynns Falls watershed at concentrations that
have the potential to affect stream ecosystem structure and function.
Rosi-Marshall concludes, "As society
continues to grapple with aging wastewater infrastructure and escalating
pharmaceutical and illicit drug use, we need to consider collateral damages to
our freshwater resources. More work is needed on the ecological fate of these
pollutants and the threat they pose to aquatic life and water quality.
Ultimately, solutions will lie in innovations in the way we manage