Recent studies and published articles, indicate that in most of the rivers around the world, have been found hundreds of drug substances and their metabolites and they can be identified and quantified at level of traces. Of course, microorganism and atmospheric conditions will process these substances with greater or lesser complexity, consuming a shorter or a longer period of time to achieve a minimal chemical expression as the end product of degradation

Considering the aforementioned, we find ourselves with a new scenario where any Drug Substance can take on the role of an environmental contaminant

In this review, we are going to dismiss narcotraffic, drug abuse and industrial bad practices as source of pollution to focus on the path that a drug substance loaded in a pharmaceutical product follows and the environmental impact it might produce.

As soon as the medicine reach the hands of the caregiver in health institutions or the ambulatory patient the drug substance begins their final trip.

The pathway by design is the intake of the medicine to achieve a therapeutic effect, after administration the drug will be absorbed, distributed, metabolized (totally or partially) and excreted. Unmetabolized drug and its metabolites will leave the body primarily, through urine and feces. Once in the sewer, it will reach the sewage treatment plants like any other home detritus.

Expired and unused medicines are often disposed through several routes, including, disposing of unpackaged doses in the sewer. It is a common practice and recommended procedure to prevent the medication from being misused. Once in the drains, the drugs substance will start a degradation process that will be accelerated in the water treatment plants.

None of the above-described routes will avoid that, within a certain extend, drug substances reach natural water sources becoming in water contaminant or pharmaceutical pollutants.

In the last 20 years, pharmaceutical pollution has been considered more seriously and, from the regulatory perspective, an environmental risk assessment is required to be submitted as part of a submission dossier.

However, is interesting highlight the magnitude of environmental impact of drugs substance through a number of relevant findings.

The Guardian have published:

Drugs flushed into the environment could be cause of wildlife decline

…Potent pharmaceuticals flushed into the environment via human and animal sewage could be a hidden cause of the global wildlife crisis, according to new research. The scientists warn that worldwide use of the drugs, which are designed to be biologically active at low concentrations, is rising rapidly but that too little is currently known about their effect on the natural world.

Studies of the effect of pharmaceutical contamination on wildlife are rare but new work published on Monday reveals that an anti-depressant reduces feeding in starlings and that a contraceptive drug slashes fish populations in lakes…

Drugs have dangerously polluted the world’s rivers, scientists warn

…The scientists measured the concentration of 61 active pharmaceutical ingredients (APIs) at more than 1,000 sites along 258 rivers and in 104 countries, covering all continents. Only two places were unpolluted – Iceland and a Venezuelan village where the indigenous people do not use modern medicines.

The most frequently detected APIs were an anti-epileptic drug, carbamazepine, which is hard to break down, the diabetes drug metformin, and caffeine. All three were found in at least half of the sites. Antibiotics were found at dangerous levels in one in five sites and many sites also had at least one API at levels considered harmful for wildlife, with effects such as feminising fish…

From Euronew we are warned than

Rivers polluted with antibiotics could cause the ‘next pandemic’, warn scientists

…Pharmaceutical pollution poses a “global threat” to environmental and human health, according to the researchers. When antibiotics get into our waterways they make it more likely for bacteria to develop antimicrobial resistance – which is said by the WHO and UN to be one of the biggest dangers to humanity…

Harvard Medical School release an article in June 2011

Drugs in the water

Although they conclude the current level of ppb or ppm of drugs in water does not provoke any effect on humans, they noted 

…Effects on fish and wildlife

In contrast to the uncertainty about human health effects, there’s quite a bit of evidence for pharmaceuticals in the water affecting aquatic life, particularly fish. Numerous studies have shown that estrogen and chemicals that behave like it have a feminizing effect on male fish and can alter female-to-male ratios. Sources of estrogen include birth control pills and postmenopausal hormone treatments, as well as the estrogen that women produce naturally and excrete. Intersex fish — creatures with both male and female sex characteristics — have been found in heavily polluted sections of the Potomac River. Studies of fish upstream and downstream of wastewater treatment plants have found more female and intersex fish downstream from the plants, presumably because of the higher estrogen levels in the downstream water. Other research has uncovered popular antidepressant medications concentrated in the brain tissue of fish downstream from wastewater treatment plants….

Most of the recommendations to reduce the increase in pharmaceutical pollution focus on:

• Educate people about the safe disposal of medicines, both at home and in hospitals.
• Increase control over effluent at water treatment plants.
• Implement a policy for the return of unused medication to collections centers, who will dispose the medication by alternative methods (high temperature incineration) that minimize the amount of drug discarded in the water systems.