Pick up a glass, fill it from the tap and take a sip. You have just had a tiny dose of the pill your neighbour took days before. Excreted and flushed through our sewage works and waterways, drug molecules are all around us. A recent analysis of streams in the US detected an entire pharmacy: diabetic meds, muscle relaxants, opioids, antibiotics, antidepressants and more. Drugs have even been found in crops irrigated by treated waste water. The amounts that end up in your glass are minuscule, and wont lay you low tomorrow. However, someone prescribed multiple drugs is more likely to experience side effects, and risks rise exponentially with each drug taken by a person over 65. So could tiny doses of dozens of drugs have an impact on your health? We dont know what it means if you have a lifelong uptake of drugs at very low concentrations, says Klaus Kümmerer at the University of Lüneburg, Germany. These drugs have been individually approved, but we havent studied what it means when theyre together in the same soup, says Mae Wu at the National Resources Defence Council, a US advocacy group. Thirty years ago, no one paid attention to endocrine disruptors, artificial chemicals found in a variety of materials. These environmental contaminants are now linked to breast cancer and abnormal development in children. The cocktail in our water involves many more compounds, so this time we cant afford to wait for negative effects to emerge. The issue of drugs in our water came to a head earlier this year when researchers were taken aback by the discovery of some drug residues in crops irrigated with treated waste water in Israel. To see if these residues passed into the body, Benny Chefetz at the Hebrew University of Jerusalem and his colleagues focused on an epilepsy drug called carbamazepine, which they detected in cucumbers, lettuce and other produce. Volunteers who consumed an irrigated crop had a dramatic spike in the drugs levels in their urine, which took over a week to clear. Those who ate crops irrigated by fresh water saw no effect. This was a big surprise, says Chefetz, who plans to study at-risk groups such as pregnant women and children. We shouldnt worry about an instant effect in healthy adults, says Chefetz, as the levels were 10,000 times lower than from a 400 milligram pill. But we dont know what will happen with small children exposed to low levels of pharmaceuticals for a generation, he says, and its not practical or ethical to run a clinical trial. Theres no data about that. Half of all irrigation water in Israel comes from recycled waste water, a process more countries are looking to use as water scarcities become more widespread. California plans to increase its use for crops in response to drought, for example. This suggests drug residues in our drinking water are set to rise. But fresh water isnt immune either. Paul Bradley of the US Geological Survey and his team checked streams in the eastern US for 108 chemicals, a drop in the bucket of the 3000 drug compounds in use. One river alone had 45. And even though two-thirds of the streams werent fed by treated waste water, 95 per cent of them had the anti-diabetic drug metformin, probably from street run-off or leaky sewage pipes. The number of chemicals we are exposed to is very, very large, and we dont understand those impacts, says Bradley. Thats perhaps unsurprising, given the level of drug use in the US. Recent stats show one in five Americans had used three or more prescription drugs in the past 30 days. The big unknown is how these low-dose drug cocktails affect people. Usually, researchers assess risk by varying doses of one drug. They ask what dose causes a specific result, like mortality in a lab animal or signs of cancer. But you cannot assess multiple drugs in small doses over a long time period, says Kümmerer. Industry says we need sound science, but what does that mean? he says. If its a clear dose-effect relation, then we cannot establish this. Weve got hundreds of chemicals circulating in our blood that our grandparents did not have, says John Sumpter at Brunel University London. We can test each of these chemicals in turn and not see any adverse effect, but Im not sure the whole mixture doesnt do anything. Some say the industry could do more. Once drugs are on the market, they claim they have no responsibility, says Chefetz. Bodies like the European Federation of Pharmaceutical Industries and Associations disagree. A spokesperson points to efforts like a collaboration within the Innovative Medicines Initiative to generate reliable ways of judging potential risk for pharmaceuticals. Maybe we should accept we dont know what is going on and take action to minimise the risks: a precautionary approach. There are two possible solutions. One is to upgrade water treatment facilities. Its an option Switzerland has gone for, but it isnt cheap it will cost the country over $1 billion. In England, it is estimated that just removing the hormone oestradiol from sewage plants would cost billions of pounds. The public needs to decide if reducing these compounds is important enough to pay for, says Bradley. Another issue is that treatment doesnt remove all unwanted compounds and can transform some into new and unknown chemicals, says Kümmerer. He argued against the approach at the Risk Assessment of Pharmaceuticals in the Environment conference in Paris. Instead, he is calling for greener pharmaceuticals that degrade readily in the environment. Traditionally, pharma firms have focused on the stability of drugs, ensuring their products have a long shelf life. Kümmerer believes its time for a rethink. Existing drugs can be made to react and break down under conditions not found in the body, such as light or a specific pH. He has shown its possible to redesign drugs for heart disease so that they degrade faster in the environment, though these molecules require testing before clinical use. But if the companies wont play ball, perhaps we need to hit them where it hurts the bottom line. Drugs are assessed for their environmental impact but results cannot prevent them being sold. Doing so could shift thinking, but it is a big stick. Would blocking a cancer drug on environmental grounds really be acceptable? Still, a ban could encourage firms to produce greener drugs. This could create revenue for innovative companies, says Kümmerer. Its thought some are already active in this area, but keeping the research under their hats, says John Warner of the Warner Babcock Institute for Green Chemistry in Wilmington, Massachusetts. Drugs in the environment is a serious issue, but current regulations work against solving the problem by looking for stable drugs, he says. The fact you dont hear about all these great things pharma is doing in this space doesnt mean they are not doing it. However, we decide to deal with the drugs in our water, the lessons of the endocrine disruptors suggest we should start soon, even in the face of uncertainty about their effects. This hasnt been getting enough attention, says Wu. The problem hasnt been getting better because we are just ignoring it.
New Scientist, 14 September 2016 ;http://www.newscientist.com/ ;