But what about the fish? Ecotoxicology and anaesthesia
Few anaesthetists can forget the unique pleasure of memorising the many different
metabolites, effects, and clearance rates of anaesthetic drugs. However, once they
have been excreted or disposed of, our understanding of their fate and environmental
impact is much more limited, if we even consider them at all.
However, if we are to achieve the goal of providing
environmentally sustainable healthcare then we must start to
pay attention to these effects. The field of ecotoxicology, which
emerged in the 1970s, examines the adverse consequences
that substances have on the ecosystems into which they are
released. These include toxicity (potential to poison organisms),
persistence (ability to resist degradation), and bioaccumulation
(accumulation within organisms); with regard to drugs, this will
also include metabolites.
If we look beyond volatiles, many other drugs that we give to patients have the potential to cause environmental harm.
Besides excretion by the patient, pharmaceuticals may also be
disposed of directly into the environment. In the UK, hospitals
are obliged to incinerate pharmaceutical waste, but that
purchased by the public can easily enter household waste.
Even within hospitals, the disposal of pharmaceuticals can still
bypass mandated pathways, resulting in their passage to the
environment.
The obvious target for reducing the environmental impact of
anaesthesia is that of anaesthetic gases. However, if we look
beyond volatiles, many other drugs that we give to patients have
the potential to cause environmental harm. When discussing
the use of total intravenous anaesthesia as a less carbon-intense
choice, one might hear the refrain
“…but what about the fish?”
Propofol has been detected in surprising places: drinking water; the tissues of fish; and even volatile emissions from textile floor coverings
How much of a problem is ecotoxicity? Should we be worried
about the fish, and by extension, our ecosystems? We know
that a variety of pharmaceuticals enter our ecosystems [1]; they
can then cause various problems affecting humans (a rise in
multi-drug resistant organisms linked to antimicrobial agents
[2]) and animals (feminisation of male fish from exposed to
contraceptive hormones).
Within anaesthesia, propofol is one of the most widely used,
and wasted, drugs. Propofol has been detected in surprising places: drinking water; the tissues of fish; and even volatile
emissions from textile floor coverings [3]. It does not biodegrade
and it accumulates in adipose tissue. Testing has found toxic
effects on a large range of species including algae, crustaceans
and freshwater fish [4]. While the risk to the environment from
propofol is rated ‘low’, at present there is little data on the
amount of propofol entering and remaining in our ecosystems,
and the effects of chronic exposure.
Recognising that our understanding of the potential ecotoxicity
of pharmaceuticals entering ecosystems is extremely limited,
many researchers are calling for a precautionary approach.
This aims to reduce unnecessary or ineffective pharmaceutical
use, while collecting more evidence. With this in mind, perhaps
anaesthetists should consider this along with the pharmacology
required for safe and effective drug administration.
Anaesthetists might also lend their expertise to the growing field
of ecotoxicology, so that we can answer the question, "…but
what about the fish?"
Chris Allen
Association of Anaesthetists and Centre for Sustainable
Healthcare
Fellow in Environmentally Sustainable Anaesthesia
StR in Anaesthesia
Freeman Hospital, Newcastle
Ian Baxter
Consultant Anaesthetist
Freeman Hospital, Newcastle
Odunayo Oyedele
Jo Childs
Medical Students
Newcastle University Medical School
Twitter: @Chris_Allen_85; @Dr_IanBaxter
References
- Fent K, Weston AA, Caminada D. Ecotoxicology of human pharmaceuticals. Aquatic Toxicology 2006; 76: 122–59.
- Kraemer SA, Ramachandran A, Perron GG. Antibiotic pollution in the environment: from microbial ecology to public policy.
Microorganisms 2019; 7: 180.
- National Center for Biotechnology Information. Compound summary. Propofol, 2020. https://pubchem.ncbi.nlm.nih.gov/compound/Propofol (accessed 20/1/2021).
- AstraZeneca. Environmental risk assessment data. Propofol, 2017. www.astrazeneca.com/content/dam/az/our-company/Sustainability/2017/Propofol.pdf (accessed 20/1/2021).