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n world-first research, freshwater ecologist Dr Erinn Richmond
and colleagues detected dozens of pharmaceutical compounds
in aquatic insects living in Victorian creeks. She also found that
the chemicals can then move fur ther up the food chain. The
effects on native animals that are likely consuming these drugs
The results have now been published in Nature Communications.
Richmond and her team tested aquatic insects in six outer-
Melbourne creeks for a range of 98 pharmaceuticals – the widest
sample tested to date. She also tested riparian spiders that
feed on the insects to see whether the compounds – including
antidepressants, painkillers and blood-pressure medications – were
travelling through the food web.
Her research shows that pharmaceutical traces can be found in
the insects, and were transferred to the spiders. This means that
predators fur ther up the food web – platypuses, frogs, birds, bats
and brown trout – are potentially also exposed to alarmingly high
levels of drugs.
‘ Our preliminary estimates suggest that platypuses and brown trout ,
representatives of animals at the top of stream food webs, could,
in principle, be exposed to certain drugs in their diets at levels
comparable (up to 50 per cent) to prescribed human doses,’ the
‘ When we take a pharmaceutical, all of the drug is not always
used within our system, so we do excrete some, by urine typically,
that does end up in wastewater treatment facilities,’ Richmond
says. ‘Or, if you’re connected to septic, it ends up in a septic
tank. And with ageing infrastructure, the tanks aren’t necessarily
perfect; there’s some leakage, and we believe that’s a pathway of
exposure into the streams.’
Our wastewater plants weren’t designed to filter out these
compounds, and our ability to detect them is also imperfect.
Richmond sent the water and insect specimens to a laboratory at
Sweden’s Umea University for analysis. Although the tests are the
most sophisticated available, they only have the capacity to find a
fraction of the pharmaceuticals on the market.
Most polluted, least polluted
The insect samples came from six outer-eastern Melbourne
creeks. The most polluted was Brushy Creek in Chirnside Park,
downstream from a wastewater treatment plant; while the
most pristine was Lyrebird Creek in the Dandenong Ranges
National Park. She also tested Mullum Mullum Creek in Donvale,
Scotchmans Creek near the Monash Clayton campus, Ferny Creek
and Sassafras Creek.
‘ We did expect that downstream of the wastewater treatment plants
we would see the highest levels of pharmaceutical contamination,
but we presumed the national park would be relatively pristine,’ she
says. Drugs were found in Lyrebird Creek in low concentrations.
‘ We’re talking about 10 nanograms per gram of insect versus
something like 75,000 nanograms per gram of insect that we
observed in Brushy Creek.’
Traces of 69 pharmaceuticals were detected altogether, out
of the 98 that can be tested at the Umea facilities. The most
commonly detected pharmaceuticals in the insect larvae tested
were memantine (a treatment for Parkinson’s), codeine, fluconazole
(an anti-fungal medicine), metoprolol (for high-blood pressure and
angina), and mianserin (an antidepressant).
The testing showed that the pharmaceutical compounds
were passed up the food chain to the spiders. ‘Our findings
complement other research demonstrating that non-aquatic
animals may be exposed to drugs originating from aquatic
ecosystems,’ the paper says.
The research is ‘a potential underestimate of what is out there,
because we know there are thousands of different drugs available
on the market’, Richmond says. ‘Drugs interact with each other, too.
So they can combine to have a greater effect, or they can cancel
each other out. We’re not sure yet. We’re yet to explore those
Globally, more than 600 pharmaceutical substances have now
been detected in the environment , spanning all continents. And
pharmaceutical use is rising as the population grows and ages.
The effect on fish of pharmaceuticals such as antidepressants and
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