Questions & Answers

Unbalancing Act

lDo you have questions? Our experts have answers to some of your most frequently asked questions.

What is "organic" farming?

Organic farming means relying upon natural fertilizers, pesticides, and herbicides instead of synthetic chemicals. This can be important to human health and to the health of the planet because chemicals used in agriculture are one of the chief sources of water pollution. No one knows, furthermore, the degree to which exposure to these chemicals may weaken our immune system or cause cancer and other diseases.

While government agencies are still working on the exact definition of organic farming, everyone agrees that organic farmers do not use antibiotics. This is important. More and more of agriculture relies on antibiotics to prevent disease in animals that are raised in factory-like conditions. People who eventually eat these animals also ingest the antibiotics. This can have many harmful effects, and can make antibiotics less effective for when our body actually needs them to fight disease. Farmers sometimes spray antibiotics on fruits and vegetables, which can also wind up in the human body.

Read more at the main site


Is genetically modified food good or bad?

Many people feel very strongly about this question, and it is important to separate the facts from the emotions. Genetically modified food can decrease our dependence upon chemicals such as pesticides. It also has the potential to feed huge numbers of people who suffer from malnutrition. These are both extremely important accomplishments. But genetically modified seeds can escape from farms and breed with plants growing in the wild. No one knows the short or long-term impact of this. We also do not know the long-term effects—if any—of genetically modified food on people. GM food has been found, for example, to trigger allergic reactions in some people.

Genetically modified seeds can also increase the dependency of farmers, particularly in the developing world, on large corporations that create, manufacture, and price them.

Read more at the main site


Sure cutting down forests harms the environment, but don't people have to cut down trees to make a living?

Numerous studies show that people in developing countries (where most of the forest loss occurs) would have a better life and be better able to feed themselves if they sold the natural products from the forests rather than cutting down the trees and selling the lumber-or turning forests into farms.

Stripped of its green cover, rainforest soil becomes barren and thin. Often within a short period of time, farmers and ranchers abandon it and move on to new places, leaving the former rainforest a wasteland. Soil erodes and the original tree canopy never grows back. Once deforestation occurs and the balance of nature is disrupted, the land can become a breeding ground for insects and other animals that carry diseases such as malaria and leishmaniasis.

Read more at the main site


How can a lot of animals being around be good for human health?

Balance in nature is often good for human health. The best way to see this is to examine what happens when the balance is destroyed. You've probably heard of Lyme disease and may even have been asked to stay away from certain areas to avoid the ticks that carry the disease.

Ten or twenty years ago, Lyme disease wasn't much of a problem. Here's what happened: As suburbs in states such as Connecticut (where scientists first identified Lyme disease) spread into wooded areas, people increasingly came into contact with wildlife. At the same time, predator animals such as foxes died, leaving behind deer and mice, whose population began to grow because the animals that ate them were no longer around (and because there was less human hunting). Deer and mice carry the tick that transmits the bacteria that cause Lyme disease. The result: As deer and mice lived closer and closer to humans, ticks had more opportunities to bite humans—and spread the disease.

Read more at the main site


Why do dams that are built to provide electricity and control floods also harm human health?

Dams can make great contributions. But like most everything that changes the balance of nature, they can also do great harm. Dams create artificial lakes that can be breeding grounds for insects and other disease-carrying animals. Schistosomiasis, for example, often spreads via snails that thrive in the stagnant or slow-moving water that is trapped by dams. Large dams can also force huge numbers of people to move. Construction of the Three Gorges dam, now under construction along the Yangtze River in China, for example, has caused about two million people to uproot and move their homes.

Read more at the main site


What kind of city is the healthiest?

Some cities are better than others for human health. A health-friendly city has planned growth, public transportation, and uses other measures that cut people's reliance on motor vehicles; e.g., schools within walking distance. The result is less air pollution and few respiratory diseases like asthma. Fewer cars means fewer roads and parking lots-the hard, dense surfaces that create the heat island effect, which makes cities hotter and creates problems associated with global warming. Fewer roads and parking lots also mean that less runoff water (that is polluted with chemicals from car exhaust and other sources) will reach the city's watershed area, where such chemical pollutants kill wildlife.

Cities with trees, shrubs and parkland are healthier too. They cool the air, and offer more opportunity to relax and escape the stresses that can come with urban life. Trees and other plants also remove pollutants from the air—naturally.

Read more at the main site


What does survival of microbes on the moon have to do with our health?

In the early 1970s, astronauts landing on the moon found microbes flourishing on a camera that had landed with an unmanned flight in 1967. Scientists were shocked. They had not expected microbes to survive the extremely low temperatures, lack of air, and other harsh conditions. This demonstrated that microbes—including microbes that cause disease—are excellent travelers. As more and more ships and planes carry people and goods from place to place across the globe, the ability of microbes to hitch a ride and survive means more diseases are more likely to spread to more places more quickly.

Read more at the main site


Diseases like leishmaniasis and giardias seem to occur far away. Sure, I care about other people, but do they really have anything to do with me?

In today's global world, everyone is connected to everyone else. If diseases plague people in a faraway country, they can have an impact on the economy and jobs in developed countries like the U.S. Even more importantly, the presence and the spreading of such diseases indicate that people are cutting down forests, polluting water, and contributing in other ways that disrupt the balance of nature.

Read more at the main site


If we can get medicines from human-made chemicals, why do we need plants?

Human-made chemicals do provide countless medicines. But even the best scientists, working the most powerful computers and large databases, cannot create medicines whose chemicals are as complex as those that nature designs. Nature does things, furthermore, in ways that humans can't imagine-or replicate. One example is paclitaxel, a chemical that fights many types of serious cancers. It comes from the Pacific Yew tree and kills cancerous cells by making them too rigid to reproduce. Before they started studying chemicals from the Pacific Yew, scientists had never even thought of trying to kill cancer cells in this manner.

Read more at the main site


Why do plants make medicines that help people?

Like all living things, plants work to survive. Consider all the things that can harm plants: insects, microbes, and animals that want to eat them. So over hundreds of millions of years, plants have devised an arsenal of chemicals that kill or repeal their enemies. Just like your body has an immune system that fights off microbes that give you a cold, plants have a defensive system that works hard to fight off microbes that make them sick.

Many of these defensive chemicals are extraordinarily powerful and complex for the simple reason that plants cannot run away. They have to stay and fight whatever is threatening them. These same chemicals can also fight the microbes that cause diseases in humans, or have other effects that promote human health.

Read more at the main site


Can animals like snakes and sharks really save our lives?

Yes. We know that snake venom can harm or kill people. Its function in nature is to kill a snake's enemies. But the powerful bioactive (having an effect on living things) chemicals in snake venom can also be transformed into medicines. One type of venom, for example, kills animals (and sometimes humans) by lowering blood pressure to such a degree that it can become fatal. One chemical from this venom, given in modified and weak doses, may become a new medicine that prevents and treats high blood pressure, one of the world's leading killers of people everywhere.

Likewise, we think of sharks as something that can harm us. And you certainly wouldn't want to be at the business end of a hungry shark. But at the same time, sharks have much to teach us. For reasons that scientists do not yet fully understand, sharks rarely get sick. Studying the chemicals that many sharks produce has already yielded promising clues that may lead to exciting new medicines to treat cancer and other diseases.

Such examples show the wide range of mysteries that nature offers-and the importance of biodiversity to human health.

Read more at the main site


Can an infectious disease cause a species to go extinct?

While destruction of habitat is the major contributor to species loss, infectious diseases can weaken a species and contribute to it being threatened with extinction. Scientists have documented one time when infectious disease clearly was the final cause for the disappearance of a species—the Polynesian tree snail, which went extinct in 1996. This is called extinction by infection.


What disease is causing frog populations to decline?

In 1998, scientists discovered that a fungal disease, called chytridiomycosis, had infected a wide range of frog species around the world. Experts believe that the bull frog, sold internationally through the food and pet trade, carries this disease. As a result, chytridiomycosis spreads as bull frogs come into contact with other species of frogs.


What is pathogen pollution?

Pathogen pollution refers to the introduction of disease-causing microbes(pathogens) and/or their hosts (infected individuals) to new locations around the world. European bird species, including pigeons and the house sparrow, for example, introduced West Nile virus to the United States.

Read more at the main site


What is an emerging infectious disease (EID)?

EIDs include diseases that have jumped from wildlife populations to humans, diseased that have become more frequent, and diseased that are entirely new to science. Examples of EIDs include HIV/AIDS, West Nile virus, and SARS.

backBack to Questions and Answers Homepage

Additional information