Environmental problems impact derms

New Orleans - Various environmental phenomena, such as the depletion of tropical rain forests, can affect human health - for instance, by eliminating the potential for lifesaving medications, says Peyton Weary, M.D., professor emeritus of dermatology at the University of Virginia and former president of the National Association of Physicians for the Environment.

"If we are cutting down the rain forests, we will no longer be able to identify chemical compounds which can fight disease," Dr. Weary says.

"Many discoveries come from a plant; the key compounds are isolated, and they are then synthesized and manufactured for market use."

"Taxol, an agent used to treat cancer, comes from the yew tree," Dr. Weary says.

"If there were no yew trees, we could not have discovered a cancer-fighting agent. We don't know how many useful drugs we are losing by destroying the rain forests."

While tropical rain forests cover only 6 percent of the Earth's surface, tropical moist forests contain half of all species. About 70 percent of the 3,000 plants identified by the U.S. National Cancer Institute as having potential anti-cancer properties are endemic to the rainforest. About 7,000 medical compounds prescribed by Western physicians are derived from plants.

The destruction of some habitation can also spread disease, notes Dr. Weary. In Argentina, for instance, the destruction of the grasslands has led to the spread of Argentine hemorrhagic fever, a condition that mice in the grasslands carried.

Dermatologists have been aware of the phenomenon of ozone layer depletion and the risks that it carries because of ultraviolet radiation's relationship to skin cancer, according to Dr. Weary.

"When the ozone disappears, the earth is more exposed to UV radiation. This can harm the skin and cause cataracts in the eye and can affect the immune system," he says.

"It's estimated that the incidence of malignant melanoma in Santiago, Chile, a city which is exposed to the hole in the ozone layer over Antarctica, increased by 105 percent between 1992 and 1998."

Instances of tropical diseases such as malaria, dengue fever and the hanta virus have been reported in the southern United States, which likely indicates the warming of the climate, Dr. Weary says.

"The phenomenon is a result of an increase in temperature in temperate climates," he says.

"At present, the issue of ozone layer depletion is more of a concern over the Antarctic and the Arctic. The peak of ozone layer depletion will occur between 2030 and 2070. To date, it hasn't affected most of the temperate climates."

Air pollution, smog and water pollution are linked to 2 million deaths in the past decade in China. It's now recognized that air pollution and smog not only cause serious lung and respiratory problems, but affect the circulatory system as well, Dr. Weary notes.

A study out of the University of Southern California in Los Angeles demonstrated that the more pollution that surrounds a person's home, the thicker the walls of the carotid artery become. Thickened artery walls are a risk factor for heart attacks and strokes.

The global population now stands at 6.3 billion and is expected to reach nearly 9 billion by 2050. The rapid population growth will contribute to malnutrition and to water and air pollution.

"There are health implications to all environmental concerns," Dr. Weary says.

"Dermatologists, like other physicians, need to be aware of those potential harms and find ways in which they can effect change."

Dr. Clarence S. Livingood, in whose honor the lecture was named, was a dermatologist who served as executive director of the American Board of Dermatology for more than 20 years.