rivers as ‘medicine cabinets’

Blogging on Peer-Reviewed Research I came across an interesting article in yesterday’s Herald. The headline read: Drug firms turn rivers into flowing medicine cabinets. (Not like any medicine cabinet I’d want to put a hand into!) It seems that some waterways in India contains alarmingly high concentrations of a whole range of antibiotics – the result of drugs companies dumping their manufacturing wastes into rivers & their tributaries. Enough of a powerful antibiotic was being spewed into one stream each day to treat every person in a city of 90,000, said the paper.

And this wasn’t journalistic hyperbole. The story’s based on a recent paper (Larsson et al.) discussing the analysis of the outflow from a wastewater treatment plant in Patancheru, India. The plant treats the wastes of around 90 drug manufacturers. Larsson & his colleagues found that

[the] samples contained by far the highest levels of pharmaceuticals reported in any effluent. The high levels of several broad-spectrum antibiotics raise concerns about resistance development. The concentration of the most abundant drug, ciprofloxacin (up to 31,000 μg/L) exceeds levels toxic to some bacteria by over 1000-fold. potential release of active pharmaceutical ingredients from production facilities in different regions.

Overall, out of the 59 pharmaceutical products detected in the wastewater, 21 were there in concentrations of at least 1 microgram/litre – & 11 had concentrations exceeding 100 micrograms/litre. One – ciprofloxacin – was present at up to a staggering 31,000 micrograms/litre – higher than what you’d expect in humans being treated with the drug! The research team calculated that around 45kg of ciprofloxacin was being lost to the waterways each day , which is equivalent to the total amount consumed in Sweden (population nine million) over an average 5-day period. This is a problem in both environmental & economic terms.

And the drugs weren’t only in the waterways, but at least some were also detected in village wells, presumably having arrived there via seepage. The drug concentrations in the wells were much lower than a normal medicinal dose, but the finding that these drugs are so widespread in the environment is a worrying one.

Why? Because human guts and wastewater plants have something in common – they both contain bacteria. So people who drink the drug-laced water from rivers or wells in the Patancheru area are effectively walking evolutionary laboratories (& the waterways are the same, except they slosh…). At least some of those drugs in the waste stream were antibiotics. So the bacteria in the locals’ guts are exposed to varying levels of antibiotics on a continuing basis – ideal conditions for natural selection to occur. What’s the betting that faecal samples from the human population would reveal a range of antibiotic-resistant bacteria? This is not good, since multiple-antibiotic-resistance in bacteria already poses serious medical problems.

And it’s further exacerbated by the fact that the industrial wastewater stream is mixed with human sewage in the wastewater plant – even more opportunity for the evolution of antibiotic resistance in the sewage bacteria. There are other potential environmental effects: necessary decomposers in the waste treatment plant may be killed off by the drugs, and those drugs were present in the plant’s effluent at levels high enough to kill off normal stream microbes & algae. This is a Bad Situation, & you have to wonder how widespread it is – the public health implications are extremely concerning.

D.G.J. Larsson, C. de Pedro, & N. Paxeus (2007) Effluent from drug manufacturers contains extremely high levels of pharmaceuticals. Journal of Hazardous Materials 148(3): 751-755 doi:10.1016/j.hazmat.2007.07.008

(Given that this work was published in 2007, it’s interesting that it’s only making global headlines now. I gues someone got round to putting out a press release?)

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