Pharmaceutical residues are finding their way into our rivers and lakes, and scientists are concerned about the effects they may have on species – including us, writes Anthony King
IN THE RIME of the Ancient Mariner
, the poet Samuel Coleridge wrote, “Water, water every where, Nor any drop to drink”. He meant salt water, but these days it could refer to rivers and lakes.
Our surface waters are less than pristine. Modern living dumps chemicals and pharmaceuticals daily into our drains and on into our rivers. Many are not removed by sewage treatment. Known consequences include new types of bugs, antibiotic resistance and fish with deranged sexual development. Irish scientists say we should reduce the quantities of these chemicals entering our waterways.
We are producing new compounds every day, says Dr Brian Quinn, an expert in novel pollutants at the Irish Centre for Environmental Toxicologyin the Galway-Mayo Institute of Technology. “Pretty much everything ends up getting into the water supply,” says Quinn. Yet many of these chemicals haven’t been well studied. “At the moment we don’t know if they are going to be a problem or not.”
Worldwide evidence has shown that pharmaceutical residues can be detected in the environment and even in drinking water. But with chemists able to measure even tiny amounts of drugs, the implications for human health are uncertain.
Martin Cormican, a professor of bacteriology at NUI Galway School of Medicine, has concerns over antibiotics entering our waterways. He believes this may be contributing to the worldwide problem of antibiotic resistance. One drug he is researching is ciprofloxacin, which is used to treat urinary tract infections and other more serious conditions. He says when a patient takes 750mg in a pill, they excrete most of the drug “in working form”.
This can rebound on patients when bacteria in the environment are exposed to this drug. Microbes may develop and transfer resistance genes to bacteria that may subsequently cause disease. Already, ciprofloxacin resistance seems to have moved from environmental into infectious bacteria. This isn't only of academic concern. The level of resistance to ciprofloxacin in E colihas increased steadily in Ireland.
“In the course of my clinical work we see ciprofloxacin resistance practically every day, so it is a significant problem,” Cormican says. Traces of drugs used in the treatment of depression and traces of oestrogen from the oral contraceptive pill have also been detected in the environment.
“We are not saying that they are proven to be doing a great deal of harm to health, but these are biologically active compounds and they are designed to have an effect in small doses,” says Cormican. He argues that “dilution is not the solution to pollution” and that we need to take a precautionary approach. It is estimated that about 3,000 different substances are used as pharmaceutical ingredients, but only a small subset of these compounds has been investigated in environmental studies.
Dr Andy Fogarty of the Athlone Institute of Technology (AIT) has studied the effects of oestrogen-like compounds on fish. These can mimic the effects of the female sex hormone oestrogen, and wreak havoc on male reproductive systems. Recently, researchers in AIT found male roach with eggs downstream of several sewage treatment plants. Just as significant, says Fogarty, was the discovery of delayed sperm production in trout near a sewage plant.
But what does this mean for our own health? Cancer pops up as a possible concern as regards oestrogen mimics, but Fogarty cautions that so many factors are involved it would be difficult to demonstrate a cancer was caused by exposure to such chemicals. “But certainly we should be concerned about oestrogen mimics in the environment,” he warns. A further worry is that these chemicals typically bio-accumulate up the food chain when consumed. “And guess who is top of the food chain? We are.”
Oestrogens can come from plastics, drugs, industrial chemicals and pesticides. Avoidance is possible but tricky. Redesigning sewage treatment plants to increase residence time can remove “the vast majority of the endocrine-disrupting chemicals that would get into the water”, Fogarty explains.
Unfortunately, inappropriate planning and building during the economic boom pushed sewage treatment plants to the brink of their capacity. Improving sewage plants costs money and Fogarty is not optimistic in today’s economic climate. Nonetheless, there are simple steps we can all take. Medical students working in Galway last year asked the public about disposal of unwanted pharmaceuticals. Quite a number said they throw them down the sink or into the toilet.
There is no scientific evidence to justify spending vast sums of money on trying to prevent medicines you take going down the drain in your urine, says Cormican, but not throwing antibiotics into our waterways is an easy step. Although many pharmacies will take back used medicines, policymakers should devise a returns scheme for unwanted drugs to allow for responsible disposal, he argues.
Just add water: How scientists are keeping tabs on the chemical flow
Sewage is messy to study – it is a complex mixture and testing the effects of drug residues on bacteria and other organisms in the lab is difficult. And the long-term human exposure risks from pharmaceuticals that reach the open environment are almost a blank slate.
“In places in the environment where you find pharmaceutical agents, you dont just find one of them. You find a whole bunch of different pharmaceuticals,” says Prof Martin Cormican.
Dr Brian Quinn is studying drugs coming from municipal effluent. He is looking at what chemicals are coming out and what effects that controlled and field exposures have on certain species. Substances such as caffeine are found in substantial quantities in our rivers, lakes and seas, but it is unlikely to have much impact on microbes or animals. But other compounds may be less benign.
“The new emerging compounds, we just don’t know yet if they are likely to have an impact or not,” says Quinn. “They are being released without any assessment being done on them.”
He says there should be more public awareness of pharmaceuticals and even all
the detergents and cleaning products we use in our houses. “The more we use, the more ends up in the environment – and the more potential there is for problems,” says Quinn.
A seemingly run-of-the-mill drug caused an unexpected yet major environmental disaster. Diclofenac decimated almost the entire vulture population in Southeast Asia, with around 99 per cent of the birds wiped out.
Diclofenac is a non-steroidal anti-inflammatory drug commonly taken to reduce pain and inflammation. It’s also taken to treat migraine. But in Asia vultures were killed after they had fed on the carcasses of animals which had been treated with veterinary diclofenac.
The medication joined the list of priority drugs when it was earmarked this summer for special attention by the European Commission. Quinn is currently studying the effects of this drug on mussels and fish, so-called “indicator organisms”, to investigate the potential harm to animals exposed in the environment and to see what levels people may be unintentionally exposed to.
In his labs, algae will be exposed to these novel pollutants that will then be fed to mussels who are in turn eaten by fish. The idea is to see if drug transfer can occur by eating contaminated foods that may potentially result in human exposure. He will go through the same tests and experiments for gemfibrosil, a pharmaceutical used for lowering cholesterol.
