What goes in must come out – in some form or another. Our bodies are relatively efficient processing systems, so when we have extracted what we require from pharmaceutical agents, the rest is excreted in urine and faeces and finally makes its way to our wastewater.  Seventy-two percent of these pharmaceuticals end up in our urine and 28% in our faeces, nearly half of it in its original active form.

Human waste recycling will be a major challenge this century.

Fortunately, wastewater treatment plants remove a great number of the commonest drugs from the water supply. For example, the painkiller acetaminophen/ paracetamol, which has the highest concentration in sewer and influent samples, is fully eliminated during treatment.

Despite these rigorous attempts at controlling the levels of active pharmaceuticals that make it from our toilets into our wastewater, there are more than 50 active pharmaceutical ingredients still found leaving water treatment plants worldwide. Hydrochlorothiazide, a drug that treats high blood pressure, was found in every sample taken. Other high blood pressure medications and the mood stabilizer, carbamazepine, were found in more than 90% of the samples.

Every day our drinking water becomes more regulated. Many of us buy bottled water now.  However, these strategies will never counter the unregulated water we consume in our food products. Even when the human drinking water has been cleared of pharmaceuticals, the residues of drugs remain in the plant and animal kingdoms. For example, plants retain large amounts of anti-inflammatory drugs and asthma medications. Further up the food chain, fish and molluscs contain large amounts of mood-altering drugs.

We would like to think that products grown by organic farms are immune. Unfortunately, that is not the case. Despite organic certification, the soils and farming water at these facilities may derive from contaminated sources. The evidence that organic products contain similar levels of heavy metals such as copper, nickel and zinc, to their non-organic counterparts is not new. So, watch out when eating your tomato < lettuce < onion < carrot < potato and root vegetables.

Newer evidence is emerging highlighting toxic levels of antibiotics. For example, tetracyclines are found in organic open-field soils at higher concentrations than those found in greenhouse soils.

To date, no causal links have been made between excreted pharmaceuticals and long-term ill effects in humans. What is certain, however, is that human waste recycling will be a major challenge this century.  Ironically, while some observers catastrophize the increasing contaminants in our water and food supplies, the life expectancy of humans continues to lengthen.