A new class of water pollutants has been discovered during the past six years. Pharmaceutical drugs given to people and to domestic animals (including antibiotics, hormones, strong pain killers, tranquilizers, and cancer chemotherapy chemicals) are being measured in surface water, in groundwater, and in drinking water at the tap. Large quantities of drugs are excreted by humans and domestic animals, and are distributed into the environment by flushing toilets and by spreading manure and sewage sludge onto and into soil.
German scientists report that anywhere from 30 to 60 drugs can be
measured in a typical water sample, if anyone takes the time to do the proper analyses. (Science News 153 [2]: 187-189, 21 Mar. 1998) The concentrations of some drugs in water are comparable to the low parts- per-billion (ppb) levels at which pesticides are typically found. Some people find this is reassuring, but others are asking, "What is the long-term effect of drinking, day after day, a dilute cocktail of pesticides, antibiotics, pain killers, tranquilizers and chemotherapy agents?" Of course no one knows the answer to such a question. It is simply beyond the capabilities of science to sort out the many chemical interactions that could occur in such a complex chemical soup.
The first study that detected drugs in sewage took place at the Big Blue River sewage treatment plant in Kansas City, USA, in 1976. The problem was duly recorded in scientific literature (Life Sciences 20[2]:337-341, Jan 1997)and then ignored for 15 years. In 1992, researchers in Germany were looking for herbicides in water when they kept noticing a chemical they couldn't identify. It turned out to be clofibric acid (CA), a drug used by many people in large quantities to reduce cholesterol levels in the blood. Clofibric acid is a close chemical cousin of the popular weed killer 2,4-D.
Since 1992, researchers in Germany, Denmark and Sweden have been
measuring CA and other drugs in rivers, lakes, and the North Sea. To everyone's surprise, it turns out that the entire North Sea contains measurable quantities of clofibric acid. Based on the volume of the Sea, which is 12.7 quadrillion gallons, and the average concentration of CA, which is 1 to 2 parts per trillion (ppt), researchers estimate that the North Sea contains 48 to 96 tons of clofibric acid. (Environmental Science and Technology 32[1]: 188-192, 1998).
The Danube River in Germany and the Po River in Italy also contain measurable quantities of clofibric acid.[5,6] Of more immediate concern to humans is the finding that tap water in all parts of the city of Berlin contains clofibric acid at concentrations between 10 and 165 ppt. The water supplies of other major cities remain to be tested.
Drugs are designed to have particular characteristics. For example, 30 per cent of the drugs manufactured between 1992 and 1995 are lipophilic, (Chemosphere 36[2]:357-393, 1998). This means that the drugs tend to dissolve in fat but not in water, and this gives them the ability to pass through cell membranes and act inside cells. Unfortunately, it also means that, once they are excreted into the environment, they enter food chains and concentrate as they move upward into larger predators. Many drugs are also designed to be persistent, so that they can retain their chemical structure long enough to do their therapeutic work. Unfortunately, after they are excreted, such drugs also tend to persist in the environment. A landfill used by the Jackson Naval Air Station in Florida contaminated groundwater with a plume of chemicals that has been moving slowly underground for more than 20 years. The drugs pentobarbital (a barbiturate), meprobamate (a tranquilizer sold as Equanil and Miltown) and phensuximide (an anticonvulsant) are still measurable in that groundwater plume.(Chemosphere, ibid.)
When a human or an animal is given a drug, anywhere from 50 to 90 per cent of it is excreted unchanged. The remainder is excreted in the form of metabolites --chemicals produced as by-products of the body's interaction with the drug. Researchers report that some of the metabolites are more lipophilic and more persistent than the original drugs from which they were derived.( Chemosphere, ibid.)
Another problem resulting from drugs in the environment is bacteria developing resistance to antibiotics. The general problem of antibiotic-resistant bacteria has been recognized for more than a decade. Antibiotics are only useful to humans so long as bacteria do not become resistant to their effects. Bacteria exposed to antibiotics in sewage sludge, or water, have an opportunity to develop resistance.
Source: by Peter Montaque, Rachel's Environment & Health Weekly No. 614, 3 September, 1998. PO Box 5036, Annapolis, MD 21403, USA; tel. 410-263-1584; fax 410-263-8944; e-mail, erf@rachel.org; for transcript, see www.monitor.net/rachel/