"We know we are being exposed to other people's drugs through our drinking water, and that can't be good."~Dr. David Carpenter, director of the Institute for Health and the Environment of the State University of New York at Albany.

Here’s the good news - Americans are finally getting free pharmaceutical grade drugs. Now here’s the bad new - we don’t get to pick which drugs. At least 41 million Americans are daily ingesting potentially dangerous cocktails of antibiotics, anti-convulsants, mood stabilizers and sex hormones every time they have a glass of water, shows an Associated Press investigation.

While researchers do not know what risks result from decades of persistent exposure to random combinations of pharmaceuticals, they know it certainly cannot be good. Recent studies have found that these low-level combos can have an alarming effect on human cells and wildlife.

While the concentrations of these pharmaceuticals are tiny, measured in quantities of parts per billion or trillion, scientists are worried about the long-term consequences to human health. Water providers rarely disclose results of pharmaceutical screenings, unless they have to. They say that the public "doesn't know how to interpret the information" and might be unduly alarmed by knowing the truth.

The drugs get into the water through urine and people who flush their unused excess medications down the toilet. While wastewater is treated before it is discharged into reservoirs, rivers or lakes, most treatments do not remove all drug residue before some of the water is piped right back to consumers.

"We recognize it is a growing concern and we're taking it very seriously," said Benjamin H. Grumbles, assistant administrator for water at the U.S. Environmental Protection Agency.

The federal government doesn't require any testing and hasn't set safety limits for drugs in water. Even bottled water won’t solve the problem since many bottlers simply repackage tap water, and do not typically treat or test for pharmaceuticals, according to the industry's main trade group. Nor are all home filtration systems equally effective! Contamination is not confined to the United States. More than 100 different pharmaceuticals have been detected in lakes, rivers, reservoirs and streams throughout the world. Studies have detected pharmaceuticals in waters throughout Asia, Australia, Canada and Europe - even in Swiss lakes and the North Sea.

But the US is the leader of the pack when it comes to prescription drug use. Over the past five years, the number of U.S. prescriptions rose 12 percent to a record 3.7 billion; while nonprescription drug purchases held steady around 3.3 billion, according to IMS Health and The Nielsen Co. But even with all of this drug taking, Americans rank very poorly for longevity and overall health compared to other developed nations.

"People think that if they take a medication, their body absorbs it and it disappears, but of course that's not the case," said EPA scientist Christian Daughton.

Some drugs, including widely used cholesterol fighters, tranquilizers and anti-epileptic medications, resist modern drinking water and wastewater treatment processes. Plus, the EPA says there are no sewage treatment systems specifically engineered to remove pharmaceuticals.

Reverse osmosis has been found effective at removing virtually all pharmaceutical contaminants. However, it is too expensive for large-scale use and leaves several gallons of polluted water for every one that is made drinkable. Another issue is that adding chlorine, a common process in conventional drinking water treatment plants, makes some pharmaceuticals even more toxic.

Human excrement, however, isn't the only source of contamination. Cattle, for example, are injected with slow release implants of trenbolone, an anabolic steroid used by some bodybuilders, to bulk them up for slaughter. A German study showed 10 percent of the steroid passed right through the animals and into our ecosystem.

Water downstream of a feedlot in Nebraska had four times more steroid levels as the water taken upstream. Consequently the male fathead minnows living in the downstream area had low testosterone levels and small heads.

Mary Buzby, director of environmental technology for drug maker Merck & Co. Inc. admits, "There's no doubt about it, pharmaceuticals are being detected in the environment and there is genuine concern that these compounds, in the small concentrations that they're at, could be causing impacts to human health or to aquatic organisms."

Laboratory research has found that small amounts of medication have affected human embryonic kidney cells, human blood cells and human breast cancer cells. The cancer cells proliferated too quickly; the kidney cells grew too slowly; and the blood cells showed biological activity associated with inflammation.

These trace amounts of drugs in our drinking water might not be cause for concern if water was an infrequent indulgence, rather than a substance that we must consume daily in large quantities throughout our lifetimes. Chronic low-level exposure to certain drug classes could be dangerous, especially to children, elderly and pregnant women, say scientists. Chemotherapy drugs act as a powerful poison. Hormones can effect reproduction and development. Medicines for depression and epilepsy can damage the brain or change behavior. Antibiotics allow human germs to mutate into more dangerous forms.

Environmental groups have kept an eye on regulated contaminants such as pesticides, lead, and PCBs, which are present in higher concentrations and clearly pose a health risk, but some experts worry that medications may pose just as serious of a danger. Unlike the majority of pollutants, drugs are specifically designed to act on the human body. Depending on the drug, even a very small dose can trigger a change in the human body.

Professor John Sumpter at Brunel University in London, who has studied the effects of trace hormones and drugs says, "These are chemicals that are designed to have very specific effects at very low concentrations. That's what pharmaceuticals do. So when they get out to the environment, it should not be a shock to people that they have effects.”