Astonishingly, traces of pharmaceutical drugs are likely to be present in every glass of tap water you drink.
Years ago, a major concern was that contraceptive pill residues were getting into drinking water (see box, page 7), but that fear has now spread to prescription drugs in general, as surveys across Europe and the US reveal that your tap water is widely polluted with everyday medications.
What's more, chlorination isn't helping-and, in fact, may be making a bad situation worse.
Among the first whistleblowers was an unlikely bunch of scientists from the US Geological Service. Although the USGS usually shuns controversy, around six years ago, these normally mild-mannered boffins were sufficiently concerned to sound the alarm.
"Improved laboratory techniques have led to the discovery [in water supplies] of microbial and viral contaminants, pharmaceuticals, and hormones that could not be measured before," they declared in their 2002 annual report.
Prior to this, if the problem was recognized at all, hazardous compounds in the water supply were assumed to be adequately dealt with by the usual water-treatment methods. However, in 2004, the USGS put this assump-tion to the test-with staggering results.
Their scientists visited a large American water-treatment plant, and tested the quality of both the water entering the plant and the drinking water leaving it. The plant obtained its water from two small rivers, referred to as its 'water-shed'.
In these apparently pristine waters, the scientists found "up to 40 . . . prescription and non-pres-cription drugs and their metab-olites, fragrance compounds, flame retardants and plasticizers, cos-metic compounds, disinfectants, detergent metabolites, and plant and animal steroids". These compounds, they discovered, had been deposited into the rivers from two sewage-treatment plants that were located upstream-all of which was perfectly legal.
Although the contaminants were potentially a serious concern for the fish and wildlife, the acid test was whether or not the water-treatment facility could prevent them from getting into the human drinking-water supply.
The answer was a resounding no. Although the standard chlorination treatment took care of the detergents, disinfectants and steroids, it did not completely eliminate the rest, allowing a substantial proportion of drugs to enter the drinking water-up to 17 contaminants. "This study provides the first documentation that many of these compounds can survive conventional water-treatment pro-cesses and occur in potable-water supplies," the USGS reported (Sci Total Environ, 2004; 329: 99-113).
Since then, hundreds more water supplies in the US and Canada have been tested. Most have revealed large numbers of prescription drugs in the watersheds that supply the treatment plants. In the water supply to "a major drinking water treatment facility" in Ontario, Canada, researchers found carba-mazepine, cotinine, caffeine, cyclo-phosphamide, fluoxetine, norfluox-etine, pentoxifylline, trimethoprim, ibuprofen, bezafibrate, clofibric acid, diclofenac, fenoprofen, gem-fibrozil, indomethacin, naproxen and ketoprofen.
There was also a handful of pesticides, too, including atrazine, simazine, propazine, prometon, ametryn, prometryn and terbutry (Environ Toxicol Chem, 2006; 25: 2356-65).
In the US last month, Associated Press researchers concluded a five-month enquiry into the nation's water supplies and found that nearly half of the country's watersheds are contaminated by prescription drugs-with many ending up in drinking water. Here are some of their findings.
- In Philadelphia, over 60 pharma-ceuticals or their byproducts were detected in the city's watersheds. The local water-treatment plant was virtually useless, managing to remove only a few of the drugs. Indeed, the AP researchers discovered that Philadelphians' tapwater contains a total of 56 different pharmaceuticals, including anti-biotics, pain relievers, statins, antidepressants, heart and asthma drugs, and antiepileptic agents.
- In Southern California, AP found that 18.5 million people were exposed to antiepileptic and antianxiety medications via their drinking water. Wash-ington, DC residents routinely drink six pharmaceuticals via their water supply, and 850,000 people in northern New Jersey drink water containing residues of antianxiety and heart drugs.
- In all, 24 US metropolitan areas have pharmaceuticals in their water supply.
Predictably, the water industry retaliated by owning up to drugs in the water supply-could they claim otherwise?-but insisted that it didn't matter. According to them, the levels of drug residues are too low to have any clinical effects-up to 1000 times too low, they said. One piece of their evidence is a three-year-old report by a panel of eight experts who concluded that drugs in drinking water constitute "no appreciable human health risk". Six of these experts worked for major international drug companies (Regul Toxicol Pharmacol, 2005; 42: 296-312).
However, as the USGS research-ers point out, the idea that low levels of pharmaceuticals are harmless is only an assumption.
"Little is known about potential human-health effects associated with chronic exposure to trace levels of multiple drugs through routes such as drinking water," they say. "Furthermore, drinking water safety criteria currently are based on the toxicity of individual compounds and not combinations of compounds."
Entering European waters
How do these drugs get into the water supply in the first place?
One way is simply by having people flushing them down the toilet. Incredibly, this habit is an officially recommended (by the FDA, for example) way to dispose of unused medications. Hospitals also routinely chuck liquid medications down the drain.
But the greatest source of most waterborne drugs is human urine. That's because medications are not completely assimilated by the body, and end up being excreted from the body either in their original form or as byproducts referred toas 'metabolites'. These enter the sewage system, the liquids of which are treated and then usually recycled back into the watersheds. But although the whole process may seem distasteful, that is how most of us get our drinking water. In some parts of London, for example, tap water may have already passed through the kidneys of five people (Int J Environ Res Public Health, 2006; 3: 180-4).
Indeed, last January, the Drinking Water Inspectorate (DWI), the official guardian of Britain's tap water, was sufficiently concerned to commission a special study. Among its findings was the fact that "the major source of pharmaceuticals to the environ-ment is via sewage treatment works effluent" and, in some cases, the effluent treatment was actually increasing the quantity of pharma-ceuticals by restoring metabolites back to their parent compounds. Paracetamol, for example, is more toxic after passing through a treatment works.
Because there is no routine monitoring of UK drinking water for drugs, the report admits that there is "very limited data" on the problem. Nevertheless, three major prescription drugs-carbamaze-pine, diazepam (Valium) and clofibrate-have already been detected and even the cancer chemotherapy drug bleomycin, according to the January 2008 report by the DWI and Department for Environment, Food and Rural Affairs (Defra).
Luckily, some British experts are not as dismissive of the potential hazards as their US counterparts, warning of "the exposure of the pregnant mother, or more specifically her fetus, to these drugs via drinking water" (J Hydrol, 2007; 348: 167-75).
Elsewhere in Europe, it's a similar story.
"More than 80 compounds, pharmaceuticals and several drug metabolites have been detected in the aquatic environment," say German experts. "In a few cases [these] have also been detected at trace levels in drinking water samples" (Toxicol Lett, 2002; 131: 5-17).
German rivers, for instance, are contaminated to "considerable concentrations" by drugs such as ibuprofen, carbamazepine, phena-zone, diclofenac, beta-blockers, antibiotics and even X-ray contrast agents. These are often "persistent and highly mobile, [and] can be tracked from municipal sewage to drinking water", says one authori-tative survey. One example is clofibric acid, a drug metabolite, that is "highly persistent" in the Berlin drinking water (Kummerer K, ed. Pharmaceuticals in the Environment, 2nd edn. Springer, 2004: 121-32).
In parts of Italy, it's even worse. In Lake Maggiore, recent toxicolog-ical testing detected carbamaze-pine, sulphamethoxazole, gemfibro-zil and benzafibrate, as well as a host of herbicides and surfactants. The bad news was that none of these had been removed by the local water-treatment plant, as nearly identical levels of these agents were in the drinking water, "revealing the poor performance of sand filtration and chlorination" (Anal Bioanal Chem, 2007; 387: 1469-78).
Indeed, it's now recognized that the two standard water-purifying techniques of chlorination and filtration are generally ineffectual against pharmaceuticals.
Water purification:what works?
As it happens, two relatively advanced technologies, first introduced to remove pesticides, also appear to clear pharma-ceuticals. Granular activated carbon and ozonation, when used in tandem, are claimed to remove 100 per cent of such contam-inants although, in practice, that level of perfection is probably only achievable in the laboratory.
In the real world, "some compounds have been shown to be unaffected by such processes," say environmental scientists at Imperial College in London (Trends Biotechnol, 2005; 23: 163-7). Germany, for example, has found clofibric acid impossible to remove from the drinking water (Environ Sci Technol, 2002; 36: 3855-63).
The problem is exacerbated by the lack of regulations governing the presence of drug contam-inants, unlike the case with bacteria or pesticides, where there are specific limits on the levels permitted to remain in drinking water. This means that, in most countries, drug contam-inants come under the general catch-all requirement that drinking water should not be a health hazard. In the UK, water companies have carte blanche to decide for themselves what's safe and what's not in terms of drug contaminant levels.
"It's the water companies' judgement call about when to supplement chlorination with the more advanced treatments," the UK DWI told WDDTY. "If they detect high levels of drugs in the catchment waters, companies may decide to switch over to the more advanced water treatments."
But why not employ advanced treatments all the time? As ever, the answer comes down to money. Granular activated carbon and ozonation are too expensive to justify for round-the-clock use-but even if they weren't, they're not universally available as some water companies simply don't have the equipment.
Chlorination:a problem or solution?
So, the purity of drinking water still relies on the 100-year-old technology of chlorination, which mostly works if all you want to be rid of are some bacteria and viruses. Chlorination doesn't work on some parasites like Crypto-sporidium protozoans. This micro-scopic gut inhabitant is responsible for regular outbreaks of water-borne poisoning, sometimes with diarrhoea severe enough to be fatal. It's particularly hazardous for people with lowered immunity such as the elderly and AIDS sufferers. Although water authorities try to shift the blame onto poor chlorine plant maintenance, the problem may well be intractable: fatal outbreaks have occurred in the US despite state-of-the-art equipment and water quality that is better than required by the current federal standards (Ann Intern Med, 1996; 124: 459-68).
Another major downside of chlorination is that it can react with organic matter in the water and form chlorine-related 'disinfec-tion byproducts', especially tri-halomethanes (THMs). These are present in most drinking water,but at such low concentrations that the water authorities initially dismissed them as harmless.
However, this complacency has been comprehensively undermined by a slew of epidemiological studies over the last 20 years. First, there's cancer. A Canadian study found that THMs in water double the risk of colorectal cancer in men dose-dependently: the more THMs, the more cancer cases (Cancer Epidemiol Biomarkers Prev, 2000; 9: 813-8). US studies found a doubling of pan-creatic cancer (Am J Epidemiol, 1992; 136: 836-42) and a slight increase in brain cancer (Am J Epidemiol, 1999; 150: 552-60). The strongest link is with bladder cancer, showing a 50-per-cent extra risk even with THM levels as low as 50 parts per billion-30 ppb below the US permitted level of 80 ppb (Epidemi-ology, 2004; 15: 357-67). As a result, the US National Institute of Environmental Health Sciences estimates that chlorinated drinking water "could account for 5000 cases of bladder cancer and 8000 cases of rectal cancer per year" in the US alone (Environ Health Perspect, 1995; 103 [Suppl 8]: 225-31). For those who may doubt the evidence, there's also compelling test-tube data showing clear damage to DNA, with consequent "mutagenic and/or carcinogenic . . . hazards for human health" (Mutat Res, 2002; 513: 151-7).
THMs can also be injurious at the other end of life-in the womb. One US study of more than 5000 pregnant women found that the rate of miscarriages was almost doubled among mothers who drank tap water containing more than 75 ppb of THMs (Epidemiology, 1998; 9: 134-40). This suggests that THMs can cross the placental barrier and interfere with fetal development in general-and evidence is mounting that this is indeed the case. In Norway, a five-year analysis of over 285,000 births showed a small but significant increase in birth defects in areas with moderate-to-high levels of chlorine byproducts in the water supply (Am J Epidemiol, 2002; 156: 374-82). In the more highly chlor-inated New Jersey, in areas with THMs higher than the regulation 80 ppb, a three-year study of more than 80,000 births revealed "very low birth weight . . . central nervous system defects, neural tube defects, and oral cleft defects . . . and major cardiac defects" (Am J Epidemiol, 1995; 141: 850-62).
Chlorine byproducts, present in our drinking water at vanishingly low levels, are now known to cause cancer and birth defects, problems that have taken years to show up. It may also be only a matter of time before the supposedly safe levels of drugs in our drinking water prove to be equally hazardous.
Drinking water and the Pill
The first concern about pharmaceuticals in water was over the contraceptive pill. About 20 years ago, the female hormone oestrogen and its related compounds were found to be accumulating in the effluents of sewage-treatment works. It was then found that male fish were becoming partially feminized and even hermaphroditic in some species. Research also suggested that men's sperm counts were dropping, and the finger was pointed at the sex hormones in the Pill getting into the drinking water.
Over the past decade, however, the picture has become more clouded. First, there are doubts over the sperm count data: in some countries, it isn't dropping and, in others, it's actually rising. Other question marks surround the Pill as detailed tests have shown that the main oestrogen entering water-treatment works isn't the artificial oestrogen used in the Pill, but oestrone and oestradiol, both of which are naturally produced by women and expelled in the urine.
How much water should you drink?
The received wisdom sticks with the eight-glasses-a-day rule, which means you have to drink at least a couple of litres of water a day for optimal health. At first glance, this makes sense; after all, the body loses about 1.5 litres of water a day through sweat, the breath and urine.
But in April of this year, two researchers from the University of Pennsylvania claimed to have found no evidence to support or refute this idea. Drs Stanley Goldfarb and Dan Negoianu examined the four principal alleged benefits of a high water intake-improved skin tone, increased removal of toxins, less hunger and fewer headaches-and found no evidence to support these benefits.
"Our bottom line is that there was no real good science-or much science at all-behind these claims. . ." said Goldfarb. "The kidneys clear toxins, yes, but they do it independently of how much water you take in. When you take in a lot of water, all you do is put out more urine, but not more toxins in the urine" (J Am Soc Nephrol, online 2 April 2008; doi:10.1681/ASN. 2008030274). However, there is also no evidence against them.
On the other hand, Dr Fereydoon Batmanghelidj, author of Your Body's Many Cries for Water (Vienna, VA: Global Health Solutions, 1992), has researched water intake for 20 years, and came to the conclusion that chronic dehydration can cause or exacerbate a raft of health problems such as dyspepsia, colitis, high blood pressure, general abdominal pressure, rheumatoid arthritis, back and neck pressure, angina and depression. However, his supporting evidence is mostly anecdotal, probably because clinical trials on water intake don't attract much medical interest or funding.
Cleaning up your water
- Jug filters. The simplest and cheapest method for purer water, most comprise two components: one filter that contains carbon particles to absorb contaminants; and another filter made of a resin that binds to the ions in minerals and removes them. The trouble is, they're not 100-per-cent effective. According to Brita, the leading filtered-jug manufacturer, their filters only remove 85 per cent of chlorine residues and 70 per cent of pesticides (and may or may not eliminate pharmaceuticals).
- Plumbed-in filters. These are typically installed beneath the kitchen sink with their own outlet tap at sink level. A major manufacturer in the UK is Pozzani, which makes an entry-level carbon filtration kit that claims to remove cryptosporidia, up to 90 per cent of pesticides and 99 per cent of chlorine residues. Pozzani also offers tailor-made filtration systems based on where you live, choosing the carbon filter likely to be the best at removing your local pollutants.
- Reverse osmosis. A more sophisticated plumbed-in system with a price tag to match, this claims to remove 100 per cent of chlorine residues and pesticides. The problem is that it tends to remove beneficial minerals from water as well, so do be sure to take supplements.
- Distillation. This removes everything, including every last molecule of flavour. Small domestic countertop distillation units are available, but their sales appear to be mostly confined to those with severely compromised immune systems, as most people are put off by distilled water's lack of taste. More important, the lack of natural minerals could be a health hazard. Heart disease, neurodegenerative diseases and certain types of cancer can result from having too few minerals in drinking water (Kozisek F. Health risks from drinking demineralized water, in Nutrients in Drinking Water. Geneva, Switzerland: World Health Organization, 2004).
As revealed in November 2006 by WDDTY (vol 17 no 8), bottled water is not the obvious solution to contaminated drinking water that it would appear to be. One problem is that purity regulations are far more lax than those for tap water, allowing even the likes of Perrier and Volvic to contain relatively high levels of poisons such as arsenic and phthalates. Some bottled waters have also been found to be contaminated by bacteria.Another issue is the water containers themselves. Most bottled water is stored in plastic, now known to leach a variety of hazardous chemicals into its contents, especially the hormone-disrupting bisphenol A.