By David S. Martin
CNN Medical Senior Producer

If you’re like me, you try to exercise and eat a diet with lots of fruits and vegetables. The hope, of course, is that a healthy lifestyle leads to good health. It doesn’t always work out that way.

There are two things we don’t control when we sit down at the table or head to the gym. The first is our genes. We may have a family history of heart disease or Alzheimer’s. The second is the environment: The air we breathe, the water we drink, chemicals we ingest, all can have a subtle but profound affect on our long-term health.

This year, perhaps as never before, the federal government is recognizing this link between health and the environment.

The Centers for Disease Control and Prevention today launched the Web-based Environmental Public Health Tracking Network. The site is designed to track links between air and water pollutants and such chronic conditions as asthma, heart disease, cancer and childhood lead poisoning.

As of now, the tracking network only covers 16 states (California, Connecticut, Florida, Maine, Maryland, Massachusetts, Missouri, New Hampshire, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Utah, Washington, Wisconsin) and New York City.

The CDC plans to add five more sites this summer and hopes to eventually include all 50 states.

The tracking network will help the government respond more quickly to environmental health problems and also improve our understanding of the connection between environment and health, said Dr. Howard Frumkin, director of the CDC’s National Center for Environmental Health, in a news release.

That’s also what prompted the National Institute of Child Health and Human Development to embark on a 21-year study that will follow 100,000 children from the womb to adulthood. The agency began signing up study participants in January.

All this focus on the environment and health is a reminder that while we inhabit a globe, we don’t live in a bubble.

Has the environment ever made you sick?

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

By Madison Park
CNNHealth Writer

I was 22 years old when I plucked a gray strand from my tangled black hair.

I showed my mom the strange silver hair, and she shot me the "I-told-you-so" look.  She always told me that watching TV or being on the computer  would make me prematurely gray.

Her evidence: Every computer engineer she knew got gray in her 30's, but she only knew one computer engineer. So I dismissed this as a kooky theory.

But my gray encounter sparked a curiosity. I’ve seen an occasional silver strand and sometimes a scattering of gray hairs on students, teens and even kids.  One mother wrote to CNNhealth after spotting a strand of gray hair on her 3½-year-old daughter.

Could younger people be graying earlier?  Could it be hereditary or are there environmental factors - like  TVs and computer screens– as my mother suggested?

While researchers have no definitive answers, scientists in Japan say that "genotoxic stress" damages cells which are responsible for hair color. When these melanocyte stem cells die, we get irreversible graying, according to a report released this month in the journal Cell.

Our DNAs are under constant attack by chemicals, ultraviolet light and ionizing radiation, said one of the authors, Dr. Emi Nishimura of Kanazawa University.

In nature, ionizing radiation can come from cosmic rays from the sun and stars, and radioactive materials in rocks and soil, according to the National Institutes of Health. But ionizing radiation also comes from man-made sources, such as X-rays, televisions, smoke detectors, building materials, tobacco smoke, and mining and agricultural products, such as granite, coal, and potassium salt.

"It is estimated that a single cell in mammals can encounter approximately 100,000 DNA damaging events per day,” Nishimura wrote in an email. "But is not clear which kind of sources for genotoxic stress are the major contributors to aging or hair graying."

In Nishimura’s experiment, 7-to-8-week-old brown and black mice were exposed to whole-body X-rays. "If we try lower doses (of ionizing radiation), you can see a salt and pepper pattern in their hair," Nishimura said.  "With a bit higher doses, you can see more white hair.  Most of the hair became white."

While studies in mice don't always apply to humans, they can provide scientific clues.

“We discovered that hair graying, the most obvious aging phenotype, can be caused by the genomic damage response" wrote the researchers from the Center for Cancer and Stem Cell Research at Kanazawa University in Japan. The results on mice "suggest that physiological hair graying can be triggered by the accumulation of unavoidable DNA damage."

I haven't seen another gray hair in years, but I'm on the lookout.

By A. Chris Gajilan
CNN Medical Senior Producer

It’s been one of the toughest and most complex stories I’ve ever worked on: Smokestacks belching dark clouds of lead, arsenic, cadmium into the air; children live with more than four times the safe limit of lead pumping through their blood; people who believe they have lost loved ones to the toxic conditions of where they live.

Dr. Sanjay Gupta interviews Leslie and Jack Warden in Herculaneum, MO

Dr. Sanjay Gupta and I have been traveling for the upcoming documentary “Planet in Peril: Battle Lines.” We visited the small town of La Oroya, Peru a couple of times during the past year. This town nestled in the Andes mountains is home to the Doe Run Peru smelting complex, where metal-laden rock is brought for processing into raw materials such as lead, copper and zinc. It is a place where the air irritates the eyes, befouls the mouth, stings the nostrils and heavies the chest. In this town of 35,000 people, 99 percent of children living in and around La Oroya have blood lead levels that exceed acceptable limits, according to studies carried out by the director general of environmental health in Peru in 1999.

Consider this: People shouldn’t naturally have lead in their bodies. The upper safe limit set by the World Health Organization is 10 mg/dL. But even more recent findings from La Oroya show that the situation is still very grim. We were joined there by Fernando Serrano, a St. Louis University researcher, whose 2005 study found that children had an average blood lead level of 36.1 mg/dL to 32.4 mg/dL. That’s more than three times the safe limit!

Lead poisoning is insidious. Children who have high levels of lead in their bodies can appear healthy but may suffer long-term consequences such as developmental disorders, mood disorders and in some cases, retardation. The young are most at risk because their tissue is more susceptible to the toxicities of lead.

Doe Run Peru took over the smelter in La Oroya in 1997, after it had already been operating for decades under other companies. We interviewed Doe Run Peru's president, Juan Carlos Huayhua. While his company is making major technological improvements and sponsoring community health programs, it recognizes that more needs to be done. In cooperation with the Peruvian government, Doe Run Peru runs a small nursery school for about 100 children whose blood lead levels exceeded 40 mg/dL. There are thousands of kids who live within a two-mile radius of the smelter.

Yesterday, we visited a sister company, Doe Run Missouri in Herculaneum, where lead is also processed. In that small town, the company agreed to a plan to help clean up the area, including a buyout of about 160 homes, in the area about 3/8 mile from the smelter.

In both towns the battle lines are drawn. We have found that the environmental conditions have improved in recent years. While the company and some residents and workers say they are doing all they can, others say it's far from enough.

Do you have loved ones who work in difficult environmental conditions? Have you ever had to make a choice between health and livelihood?

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

By Dr. Sanjay Gupta
Chief Medical Correspondent

With the Olympics coming up, there is a lot of concern surrounding the pollution. As the athletes have started to arrive, many of them are wearing masks. They say it is to protect themselves, whereas some in the Chinese government say it is only to be insulting.

Here are a few things to consider. According to a new study out of Northwestern University, the level of particulate matter in the air in Chicago is 20 micrograms/m3. That probably means nothing to you, other than telling you the average level of pollution of a big U.S. city. Here is what caught my eye. The level of particulate matter in Beijing: 260 micrograms/m3 - 13 times as much as Chicago. (See Study)

It is well known that high levels of particulate matter can cause inflammation in the lungs, and that a protein called Interleukin 6 is released in response. The end result may be that your blood gets a little stickier and thicker. That can cause problems such as heart attacks or strokes, especially in those with a pre-existing history.

Keep in mind when an athlete is in the throes of competition, they take in more than 100 liters of air a minute as compared to a spectator at rest, who takes in an average of 6 liters a minute. Regardless, anybody who is not used to that level of pollution is going to notice it. I was in Beijing not that long ago, (Watch Video) and I could taste those particles, smell it and feel it in the back of my throat. 

As things stand now, Beijing has taken half the cars off the road with a system of odd and even license plates. They have shut down four out of five giant furnaces in the city for the time being.

Today, we learned the athletes apologized for wearing the masks.  What do you think? Is this a real concern? Would you wear a mask during the Olympics as an athlete or even as a spectator?

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.