A pill with a glass of water, hold the pill

by revere, cross-posted at Effect Measure

One of the triumphs of 19th and 20th century public health was the provision of piped water into cities and towns. With the use of modern methods of disinfection (primarily chlorination) water as a source of mass distributed poisons rapidly receded, and with it the preponderance of infectious diseases that were the scourge of urban life. Urban water supplied were an efficient means to provide a healthy required substance, water, to the whole population and once. But of course it is also an efficient means to distribute unhealthy stuff — not just microbes but chemicals. I’ve worked on the health of effects of chemicals in drinking water for many years and I wish I could say that the chemicals that occupied much of my professional attention — solvents, organic contaminants, by-products of the disinfection process — were off the radar screen. They aren’t. They are still around and causing trouble. But now the radar screen has gotten more crowded, with blips representing chemicals that mimic hormones and more and more often, pharmaceuticals. A paper just published in the journal Environmental Science & Techonology (ES&T) is quite surprising. Surveying 29 water supplies serving more than 28 million people, the most frequently found chemicals were unregulated organics, all pharmaeuticals except for one regulated pesticide.

Here’s the top 11 (via New Scientist):

  • Atenolol, a beta-blocker used to treat cardiovascular disease
  • Atrazine, an organic herbicide banned in the European Union, but still used in the US, which has been implicated in the decline of fish stocks and in changes in animal behaviour
  • Carbamazepine, a mood-stabilising drug used to treat bipolar disorder, amongst other things
  • Estrone, an oestrogen hormone secreted by the ovaries and blamed for causing gender-bending changes in fish
  • Gemfibrozil, an anti-cholesterol drug
  • Meprobamate, a tranquiliser widely used in psychiatric treatment
  • Naproxen, a painkiller and anti-inflammatory linked to increases in asthma incidence
  • Phenytoin, an anticonvulsant that has been used to treat epilepsy
  • Sulfamethoxazole, an antibiotic used against the Streptococcus bacteria, which is responsible for tonsillitis and other diseases
  • TCEP, a reducing agent used in molecular biology
  • Trimethoprim, another antibiotic

These 11 were found in over half the source waters (at the intake to the treatment plant) but only three of them (atrazine, meprobamate, and phenytoin) made it through treatment plants into the water that comes out of our faucets. Moreover they were found in fairly small quantities (nanograms/l, i.e., parts per billion). Whether these levels are of public health concern as drinking water contaminants is a matter of debate, but they are plausibly of environmental concern. They got there by first passing through wastewater treatment plants into the environment and then into a water source and our drinking water. Thus they exposed many other organisms upstream of our kitchens and bathrooms and at much higher levels.

An interesting (and surprising) finding is that the 3 treatment plants using reservoirs with no input from wastewater and no recreational use (swimming and boating on the reservoir or lake) had the lowest number of the 51 assayed chemicals in their source waters. Four reservoirs had no direct input of wastewater but allowed recreational water use. In these source waters the number of individual chemicals was similar to treatment plants that drew water from source waters with direct input from wastewater sources.

Another surprise. Prescription information is a poor guide:

The most prescribed pharmaceutical in 2006 and 2007 in the U.S. (27), atorvastatin [Lipitor], was detected in only three source waters and was not detected in any finished or distribution waters. Conversely, the most frequently detected prescription pharmaceuticals (carbamazepine, gemfibrozil, meprobamate, sulfamethoxazole, and trimethoprim) were not included in the top 200 prescribed pharmaceuticals for 2006 or 2007. Only atenolol (ranked no. 99 in 2007) and phenytoin (ranked no. 128 in 2006 and no. 151 in 2007) were frequently detected in source water. Thus, prescription information alone is a poor proxy for source water occurrence because it does not take into account the dosage, pharmacokinetics, removal during wastewater treatment, or environmental fate. (Bennotti et al., ES&T)

It turns out that some chemicals are much more affected by oxidation by disinfectants like ozone or chlorine (less so by chloramines). Ozone was, overall, the best oxidant of pharmaceuticals.

The good news is that this may cut out one step in taking your pills with a glass of water. You may just need the glass of water.


  1. #1 Kelly Butler
    January 19, 2009

    Wondered why it was “surprising” to find that reservoir water with no input from waste water or recreational use water did not have pharmaceuticals in it. Was that the editor’s comment or the scientist’s?

    It would seem that the source of these pharmaceuticals would be twofold.. one from flushed pills and perhaps behind some of the lesser prescribed but for mental health meds and secondly, metabolism of the meds – through urine with some fecal excretion.

    kb dvm