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The subject of smoking has blackened innumerable pages since the first reports of adverse health effects appeared fifty-some years ago. Public health campaigns, scientific research, the anti-tobacco lobby, and cigarette company trials have all contributed to bring about such a change in the public conscience as would have been unimaginable half a century ago. In 1965, almost half of all American adults were cigarette smokers. By 1985, the proportion of adult smokers had fallen to about 30%. In the late nineties, California introduced anti-smoking legislation, and many other places followed suit. In 2003, New York City banned smoking in bars and restaurants. But according to the CDC, more than 20% of the US adult population still smokes.

This is the key question.

The chlorination of drinking water has saved literally millions of lives. Adding chlorine to water kills many disease-causing microorganisms and prevents people from getting sick from the water they drink. But the benefits of destroying these pathogens come at a price. Chlorine can also attack other substances in the water, transforming them into carcinogenic disinfection by-products (DBPs). On the one hand, pathogens in unchlorinated water make people ill. On the other hand, DBPs in chlorinated water present a cancer risk. This case study examines the trade-offs.

The word “radiation” often conjures up images of atomic bombs, nuclear power plants, and X-ray film. But human-made sources like these contribute only about 20% of our radiation exposure. In fact, we are bombarded with radiation quite regularly, and 80% of it comes from natural sources like cosmic rays and terrestrial radiation, including radon. In the US, radon probably contributes more than half of our radiation dose.

Radon is a colorless, odorless, radioactive gas that is naturally present in rocks and soil all over the world. It is formed by the radioactive decay of uranium, and it seeps out of the ground into the air we breathe. Radon gas enters buildings through cracks in foundations and walls and openings around pipes and wires. Although radon gas dissipates quickly in outside air, there is less opportunity for it to disperse inside, so radon levels can build up indoors.

The Environmental Protection Agency (EPA) and International Agency for Research on Cancer (IARC) have classified radon as a human carcinogen. There is concern that radon in homes might be causing lung cancer in the general population. Home inspectors often test for radon, and some people incur considerable expense to seal or ventilate a home with high radon levels. So a key question emerges:

Ecological Risk Assessment (ERA) is a scientific approach used to determine the possible impacts of human activities on the environment. The EPA defines ERA as “the process that evaluates the likelihood that adverse ecological effects are occurring, or may occur, as a result of exposure to one or more stressors.” These stressors might be contaminants like lead, non-native species like introduced plants, habitat modifications like new housing developments, or even changes in climate. In fact, a stressor is simply a change that modifies ecological systems such as lakes, streams, forests, and watersheds. The resulting ecological risks may be limited to a local scale, such as trout disappearing from a certain stream. Or they may be regional, at the scale of e.g., the Chesapeake Bay, or even world-wide, like global warming.

Estuaries are among the most complex of all ecosystems. This is where salt water from the oceans mixes with fresh water from rivers to produce one of the most unique, important, and productive of all known ecological systems. They are found on continents and islands around the world and serve as nurseries for a multitude of aquatic vertebrates and invertebrates. For millions of years these habitats have evolved to allow organisms from many phyla to develop and thrive. The dynamic nature of estuaries and the intricate relationships between flora and fauna there make this type of ecosystem one of the least understood. Scientists from many disciplines continue to study how currents, temperature, salinity, dissolved oxygen, sediment deposition, metals, and organic compounds affect the abundance and distribution of aquatic life.

Changing any of these factors will create a ripple effect throughout the estuarine system. Human-made changes which disturb the “natural order” of things generally produce a wide range of unanticipated and adverse impacts.

Baltimore’s Inner Harbor is an historic seaport, the number one tourist attraction in the city, and an iconic landmark. It is a branch of the Patapsco River, which begins about fifty miles inland and terminates as a large tidal inlet of the Chesapeake Bay. Over the past few decades, the Harbor has been transformed from an industrial waterfront into one of the best examples of urban renewal in the country.

Where oil refineries and storage tanks once stood along the banks of the Patapsco, upscale condominiums with spectacular water views now line the Harbor’s edge. Factories that spewed out metals and organic pollutants have been replaced with chic retail stores and expensive restaurants. The river merges with the Chesapeake Bay, so yachts moored in the Inner Harbor have easy access to the recreational amenities of that world-class estuary. Indeed, the dramatic conversion of the Inner Harbor into Baltimore’s jewel is one of the main reasons a prominent travel guide listed Baltimore as one of the ten most desirable tourist destinations in the US.

In order to get the best health care possible, you need to learn how to be your own . One critical part of being a wise patient advocate is to build a with your doctor. One of the key skills in building that partnership is being able to with your doctor on medical issues. You need to develop a common language with your doctor so you can honestly and candidly discuss his recommendations to you. The day is long gone when the doctor-patient relationship was based on the doctor telling the patient what the diagnosis was and what the treatment plan was, and the patient accepting everything without question.

Previous chapters of this book emphasize empowering individuals to participate in discussions about the significance and importance of medical benefits and environmental health risks. Those chapters stress the value of having the appropriate data in a format (e.g., Risk Characterization Theaters, absolute benefits and risks instead of relative benefits and risks) conducive to meaningful involvement. This book encourages the reader to determine his or her level of acceptable risk before making a decision regarding the benefits of screening tests and drugs or the risks from environmental contamination.

But how do we determine our level of acceptable risk? How did the EPA settle on what should be the level of acceptable risk for exposure to cancer causing substances? How does the medical community determine what are the acceptable benefits and risks associated with screening tests and drugs?