Pharmaceuticals, an increasing threat to aquatic ecosystems
The use of pharmaceuticals world wide is increasing and so is the pollution of river waters with pharmaceuticals! A pharmaceutical is any kind of drug used for medicinal purposes.
A recently published OECD report titled 'Pharmaceutical residues in freshwater: Hazards and policy responses' informs that about 4,000 active pharmaceutical ingredients (API) are used worldwide as prescription medicines, over-the-counter therapeutic drugs and veterinary drugs. Many of them get finally deposited into aquatic environments such as rivers, lakes, ponds, soils, biota, sediments, groundwater and drinking water.
Pharmaceuticals do not degrade easily
Pharmaceuticals in the environment are a challenge to manage as they are designed to interact with a living system and produce a response at low doses and thus can remain an environmental concern even at low concentrations. They are designed to be stable and do not degrade easily and can thus remain in the water for longer periods and affect aquatic systems. Conventional wastewater treatment plants are not designed to remove pharmaceuticals from wastewater. Aquatic organisms can get exposed to pharmaceuticals over longer periods through multiple exposure routes, and involving mixtures of substances.
The presence of pharmaceuticals in the environment has recently raised concerns in India as they can lead to adverse effects on ecosystems, including mortality, as well as changes to physiology, behaviour and reproduction of aquatic organisms living in the waters as well as on humans through drinking water.
Of greatest concern are hormones, antibiotics, analgesics, antidepressants and anticancer pharmaceuticals and hormones, antibiotics and parasiticides used as veterinary pharmaceuticals. For example, studies show that oral contraceptives can lead to feminisation of fish and amphibians, antidepressants can alter fish behaviour making them less risk-averse and vulnerable to predators, and the over-use and discharge of antibiotics to water bodies has led to the problem of antimicrobial resistance, informs the report.
However, the vast majority of pharmaceuticals have not been evaluated for their long-term toxicity making it difficult to understand the true extent of the risks that they pose to the environment and health.
Worlds rivers, including those in India are drugged!
Pharmaceutical pollution of river waters world over is rampant finds a recent global study titled ‘Pharmaceutical pollution of world’s rivers’ by Wilkinson et al published in the journal PNAS that monitored 1,052 sampling sites along 258 rivers in 104 countries of all continents, thus representing the pharmaceutical fingerprint of 471.4 million people.
Surface water samples were collected from 1,052 sampling sites that included countries in Africa, Antarctica, Asia, Europe, North America, Oceania and South America. This study that included the largest survey on rivers around the world found that middle and low income countries like India with very high rate of manufacture of pharmaceuticals had very high contamination of their rivers.
Delhi in India was found to be the fourth most polluted with 46,700 nanograms of Active pharmaceutical ingredients (API) per litres of Yamuna water. Lahore in Pakistan was the first with API per litre of 70,700 nanograms, followed by La Paz (68,800) in Bolivia and Addis Ababa (51,300) in Ethiopia. Hyderabad (12,600 nanograms) was better at 12,600 nanograms, but much worse than developed countries.
Of the 61 targeted APIs, as high as 53 were detected in atleast one sampling site. On a continental basis, sites in Asia had the highest number of API at 48 followed by Europe, Africa and North America.
Frequencies of occurence of some pharmaceuticals such as carbamazepine, metformin, caffeine, nicotine, acetaminophen/paracetamol, and cotinine were similar across continents, there were geographical differences in the occurence of some pharmaceuticals.
For example, ingredients of anti-diabetic medicines were found to be maximum in India at 21,000 nanograms per litre followed by stimulants at 20,400 nangrams per litre, painkillers at 3,060 nanograms per litre and anti-epileptic medicines at 2,000 nanograms per litre.
Types of pharmaceuticals in Indian rivers
Another study titled 'A review on emerging contaminants in Indian waters and their treatment technologies' published in the journal Nature, Environment and Pollution Technology on emerging contaminants (ECs) in aquatic environments in India found that pharmaceuticals are the second largest polluting contaminants in rivers in India following pesticides.
This is because as high as 78 percent of the sewage generated in India that includes medical and pharmaceutical wastes remains untreated and is discharged in rivers, groundwater or lakes.
Some of the contaminants like carbamazepine, sulfamethoxazole, caffeine, triclosan, triclocarban, perchlorate, sucralose and organochlorine pesticides are commonly present in the river waters. The review finds that antiepileptic products, antibacterials and BUVs are found in high quantities in the Kaveri, Tamiraparani and Vellar rivers and Pichavarom mangroves in Tamil Nadu.
Ahar river in Udaipur city too is highly polluted and studies have found that its waters are contaminated with presence of around 19 pharmaceuticals including 4 antibiotics. While the quality of river water is good where it originates, the river gets contaminated as it moves through urban areas and the concentrations of emerging contaminants increase as it passes through densely populated regions due to the discharge of domestic wastewater into the river.
The river has been found to have high amounts of caffeine, diuretics, NSAID, antibiotics, hypoglycemic drugs, Beta-adrenoreceptor antagonists, Analgesics, antineoplastics, calcium channel blockers, beta blockers, mosquito repellants, UV stabilisers.
The river Ganga and the groundwater near the Ganga basin too is highly polluted with NSAID, caffeine, diuretics, antibiotics and antibacterials. The Musi river in Hyderabad has large amounts of antibiotics, antibacterial and antifungal drugs, enzyme inhibitors, hormonal residues while the Yamuna at Delhi has been found to have a large amount of antibiotics. High amounts of antibiotics in the rivers are leading to rise in antibiotic resistant bacteria in the river waters in India.
Read more on antibiotic resistance here
While pharmaceuticals can be highly toxic to aquatic and terrestrial life, vegetation and human communities, biological treatment and adsorption are not very effective in removal of the contaminants. Advanced oxidation processes using visible light-driven photocatalytic ozonation are found very effective for the removal of most of the contaminants while perfluorinated chemicals need to be removed by electrochemical methods, informs the paper.
Poor regulatory mechanisms hinder progress
At the same time, there are no proper regulations on emerging contaminants (ECs) such as pharmaceuticals in many countries due to shortage of toxicological data. In India, the drinking water standards include the regulatory standards for only a few pesticides in the Indian Standards (IS 10500). The water treatment plants and WWTPs are not monitored for the presence of ECs.
The World Health Organisation (WHO) has now published extensive regulatory standards for several classes of contaminants. Regulation and monitoring are extremely important and need to be done on an urgent basis to mitigate the ill effects of ECs such as pharmaceuticals on human health and the environment, argues the paper.