VIENNA-River systems around world are coursing with over-the-counter and prescription drug waste harmful to the environment, researchers said other day.

On current trends, the amount of pharmaceutical effluence leaching into waterways could increase by two-thirds before mid-century, they told a major science conference in Vienna.

“A large part of the freshwater ecosystems is potentially endangered by the high concentration of pharmaceuticals,” said Francesco Bregoli, a researcher at the Delft Institute for Water Education in the Netherlands, and leader of an international team that developed a method for tracking drug pollution “hotspots”.

A large number of drugs found in the environment - analgesics, antibiotics, anti-platelet agents, hormones, psychiatric drugs, anti-histamines - have been detected in nature at levels dangerous for wildlife. Endocrine disruptors, for examples, have notoriously induced sex changes in fish and amphibians.

Bregoli and his team used a common anti-inflammation drug, diclofenac, as a proxy, or stand-in, to estimate the presence and likely spread of other medications throughout freshwater ecosystems. Both the European Union and the US Environmental Protection Agency have identified the drug as an environmental threat.

Veterinary use of diclofenac, for example, has driven a sub-species of vultures on the Indian subcontinent to the brink of extinction.

More than 10,000 kilometres of rivers around the globe have concentrations of the drug in excess of the EU “watch list” limit of 100 nanogrammes per litre, the new research found.

“Diclofenac emissions are similar to any of thousands of pharmaceuticals and personal care products,” said Bregoli, who presented his findings at the annual meeting of the European Geosciences Union. Global consumption of diclofenac tops 2,400 tonnes per year. Several hundred tonnes remain in human waste, and only a small fraction - some seven percent - of that is filtered out by treatment facilities. Another 20 percent is absorbed by natural ecosystems, and the rest find its way to the oceans.

Bregoli and his team developed a computer model to predict current and future levels of pharma pollution based on criteria such as population densities, sewage systems, and drugs sales.

In other research presented at the conference, scientists found that the rapid expansion of sewage systems in large urban areas has sharply increased river pollution, because much of the effluence is not adequately treated.

“In 2000, sewage was a source of pollution in about 50 percent of the rivers in the world,” said Maryna Strokal, a scientist at Wageningen University & Research, in the Netherlands.

“By 2010, sewage was a source of pollution in almost all rivers worldwide.”

Antibiotics and chemicals waste is also driving the evolution of drug-resistant bacteria, UN Environment warned in a study in December.

Between 70 and 80 percent of all antibiotics consumed by humans and farm animals - totalling thousands of tonnes - find their way into natural environments, the UN agency said in a report.

Toxic levels of arsenic in Amazon basin well water

Shallow wells dug for drinking water in the Amazon basin in order to avoid polluted rivers contain up to 70 times the recommended limit of arsenic, researchers warned other day.

Samples taken from 250 sites along the Amazon - the first systematic analysis of the region’s well water - also revealed hazardous levels of manganese and aluminium, they reported at a conference in Vienna. “Faced with polluted rivers, many rural communities rely on groundwater as a source of drinking water,” lead researcher Caroline de Meyer, a scientist at the Swiss Federal Institute of Aquatic Science and Technology, told AFP.

“In parts of the Amazon basin, groundwater contains these trace elements in concentrations that are potentially harmful to human health.”

“Contamination should not be underestimated - all our data point in the same direction,” she added.

Levels of manganese were up to 15 times higher than World Health Organization (WHO) limits, while aluminium exceeded WHO standards by up to three-fold. The elements detected occur naturally, and do not come from industrial pollution, the researchers said.

Chronic exposure to arsenic is linked to cancers of the liver, kidney and bladder, as well as heart disease.

It is also thought to contribute to miscarriages, low birth weights and poor cognitive development in children.

In Bangladesh, where arsenic in well water has been a known health hazard for decades, the element is blamed for some 40,000 premature deaths each year.

Manganese poisoning can cause permanent neurological damage, while the impacts of sustained exposure to aluminium are less well understood.

Rural communities in the Amazon basin traditionally rely on rivers and rain to meet freshwater needs.

But with increased pollution from mining, logging and industrial activities, they have also turned to digging wells.