Drugging our waters

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A recent visit to Denmark made me realise that the global challenge of pharmaceuticals and personal care products (PPCPs) in wastewater was even more onerous than I thought. Despite being one of the most sustainable countries in the world, and equipped with advanced water technologies, Denmark has managed to build its first full-scale dedicated WWTP for treating hospital wastewater only recently. Most hospitals are discharging their wastewater to municipal treatment plants, which as insiders know too well, are woefully inadequate to deal with PPCPs.

In November 2013, the findings of the International Joint Commission, a consortium of officials from the US and Canada who studied the Great Lakes revealed that only half of the 42 compounds that were examined in the study were removed by WWTPs. Amongst the chemicals that had low rates of removal in treated effluent were a herbicide, an anti-seizure drug, two antibiotic drugs, an antibacterial drug and an anti-inflammatory drug.

Sceptics might point out that it is only thanks to the new, hi-tech instruments that we are able to detect contaminants right down to ppb level. We are finding pharmaceuticals in water today only because we have the capability to measure them, they say. The specific impact of most of these contaminants of emerging concern on the health of people and aquatic life remains unclear.

However, it cannot be ignored that it is not one or two contaminants that humans and aquatic animals are being exposed to; but a whole mix of PPCPs acting together. Rising populations are putting a much higher and diversified drug burden on the environment. Newer drugs are being synthesised and prescribed today than a few decades ago. There is much evidence linking the feminisation of fish and poor development of organs to increased exposure to oestrogen and synthetic hormones. It would be foolish to sit back and allow an uncontrolled number of new and emerging chemicals into the environment simply because we are unable to establish direct impact.

Yet, this is exactly what is happening. Nanomedicines, are showing much promise in treating cancers and other diseases, however their impact on the environment is unknown. When excreted by humans, it is possible that the super-tiny compounds can easily make their way through treatment plants. Once in nature, their particles can perhaps be absorbed easily by plant and animal organisms and make their way up the food chain.

Lessons can already be learned from the plastic microbeads fiasco. These microbeads were added to facial and body cleansers and even toothpastes to give a polishing effect. They are so small that they cannot be caught by filters in treatment plants. No one sounded alarm bells when these products were marketed worldwide. It has been found that these potentially carcinogenic substances, which can also cause birth defects in humans are being consumed by fish and possibly climbing up the food chain. Several countries are considering bans of products that contain plastic microbeads or have already legislated to ban them. But it will not be easy to make them disappear from the environment so quickly.

The argument for not having discharge standards for PPCPs is that their impacts are not properly known. But why are the authorities dragging their feet in setting standards for endocrine disruptors and oestrogens, whose impacts have been well-documented? Why are the manufacturers of non-essential products such as cosmetics allowed to market potentially damaging formulations without enough research?

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