Pharmaceuticals are essential for human and animal health, but they become an environmental concern when their residues enter the environment. Pollution of pharmaceuticals for human use can occur from excreted residues that are not absorbed after consumption, as well as from improperly discarded unused or expired medicine. While it is hard to address the former, the latter is more straightforward.
A significant share of household medicine becomes waste, and the volumes are steadily increasing due to trends in pharmaceuticals consumption
Household medicine can become waste for numerous reasons, such as early recovery, therapy changes, non-adherence or prescription and purchasing errors. The amount of household medication that remains unused and becomes waste can be significant. A study in the United States estimated that up to 42% of prescription drugs remain unused  and six out of ten patients reported having opioids left over after their treatment completed.  In France, an estimated 17,300 tonnes of pharmaceuticals became waste in 2019, approximately 260g per capita. 
With pharmaceutical consumption rising, the environmentally sound management of medicines that remain unused or expire becomes ever more important. Ageing and growing population, a rise of chronic health conditions, availability of inexpensive generic treatments and changes in clinical practice all contribute to increased pharmaceutical usage. Over the past two decades, per-capita consumption of lipid-modifying agents (such as cholesterol-lowering statins) has increased by a factor of nearly four and per-capita consumption of anti-diabetic and anti-depressants has doubled in OECD countries.
Improper disposal of unused or expired medicine is widespread and results in significant environmental contamination and public health risks
Medicines flushed via sinks and toilets enter sewage waters and risk leaking into freshwater systems, as conventional wastewater treatment plants are not designed to remove pharmaceutical residues. Even pharmaceuticals that are removed during treatment process may still enter the environment, when sewage sludge is applied as fertiliser on agricultural land (“landspreading”) or composted, both common practices around the world. Pharmaceuticals disposed of in residual household waste can also leach into the environment, when this waste is landfilled.
Ecotoxicological studies show worrying effects of pharmaceuticals on ecosystem health. Observed impacts on wildlife include traces of oral contraceptives causing the feminization and reproductive failure of fish and amphibians and residues of psychiatric drugs altering fish behavior.  Leaked antibiotics can also contribute to the development of antimicrobial resistant bacteria.
In addition to environmental impacts, unused or expired medicines constitute wasted healthcare resources and can present a possible public health risk of accidental or intentional drug and poisoning.
What needs to be done to minimise and better manage pharmaceutical household waste?
The recently published OECD report, Management of Pharmaceutical Household Waste provides three key recommendations to limit environmental impacts from unused or expired medicine.
I – Waste prevention
A first priority is to avoid medicine waste, where possible. Shorter prescription cycles and prescribing smaller amounts, as well as adjusting packaging sizes help to minimise the amount of medicines left over after recovery or in case of therapy changes. For instance, France recently passed a law to allow community pharmacies to hand out prescription medicine, including antibiotics, per individual units. 
As well, redistribution can help to avoid medicine wastage. To date, these initiatives are relatively niche and face hurdles regarding quality assurance and counterfeits. However, in The Netherlands, a government-funded study is assessing the feasibility of implementing a re-dispensing process for unused oral anticancer agents, with a first pilot study underway involving 1,150 participating patients from four hospitals. 10
II – Collection and treatment of unavoidable waste
Whilst prevention is key, fully eliminating medicine waste is unrealistic. For instance, some patients may recover more rapidly than foreseen, change their treatment or not adhere to prescribed treatments. Separate collection of unused medicines is useful to avoid leakage of this unavoidable pharmaceutical waste into the environment via sewage waters or landfills, as well as to avoid misuse.
Various countries have separate collection systems in place. Take-back schemes organised as part of an extended producer responsibility (EPR) approach appear to be effective in organising environmentally sound collection and treatment, whilst also implementing the polluter pays principle. In the United States, a number of EPRs for pharmaceutical waste exist on state, county or city level. 
Ideally, drug take-back should be available to consumers year-round at convenient collection points and free of charge to minimize transaction costs compared to other disposal routes. Pharmacies have shown to be suitable collection points. In addition to the availability of take-back options in pharmacies in some US states, the US Drug Enforcement Agency (DEA) organises nationwide take-back collection events once every six months for citizens to return their unused medicines.
III – Raising awareness
Whilst take-back options exist in various countries, awareness among the public is limited. In a US survey, 45% of the respondents did not recall receiving information on proper disposal practices  and do not know about proper disposal of unwanted medication.  In the Netherlands, 17.5% were unaware that liquid medicines should not be flushed. 
Well-focused communication campaigns are essential and several EPR schemes require a share of the scheme’s budget to be spent on communication and outreach. In addition to public or social media campaigns, doctors and pharmacists have a key role in informing the public about the appropriate disposal of their unused medicines, for instance through information leaflets handed out with products.
To Find out more about the issue of pharmaceutical household waste, click to here download the report: OECD report, “Management of Pharmaceutical Household Waste”
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