CLEANUP TARGET-The Santa Susana Field Laboratory's Area 1 burn site. Whether it's coming from a nuclear meltdown, a television set or the concrete below our feet, we live in a world awash with radiation.

"There is no doubt that radiation is bad, but there is also no doubt that we are living in it," said Dwayne Doty, a physics professor at Cal State Northridge. "We're bathed in a radiation field-not a strong field, but definitely a measurable one. Our concern should lie in whether the radiation we detect is above this normal background level."

The topic of radiation and its effect on humans is at the heart of the recent study released by the Santa Susana Field Laboratory Panel. That report, which was compiled by 17 scientists from across the country, says there is evidence of a link between a nuclear meltdown that occurred at the Rocketdyne testing facility in 1959 and an unusually high rate of cancer in surrounding areas.

But what exactly is radiation? What causes levels to be "too high?" And most important, when can it be harmful?

The process of radiation occurs when atomic particles, the building blocks of life, lose an electron and alter the structure of their atom.

As Albert Einstein revealed to the world in his famous formula, this extra energy escapes from the atom in the form of matter or in electromagnetic waves.

Materials that are radioactive can release energy in three forms: alpha particles, beta particles and gamma rays. Gamma rays are electromagnetic waves with extremely short frequencies and are the most penetrating form of radiation.

"This is the kind of radiation that comes right out of the soil and into our bodies," Doty said.

Beta particles travel as quickly moving electrons. While they can cause great harm to the body, they are easily shielded and can be stopped by a thin sheet of aluminum, according to Doty.

"This type of radiation is not usually harmful unless it enters the body somehow," Doty said. "If someone were to eat something that was emitting beta particles, it would be very dangerous. Their blood and bones would absorb all the radiation that was being emitted by that material."

Alpha particles are the most rare form of radiation and travel in the form of a helium atom without electrons. They are very weak and can be stopped by a few inches of air or a sheet of paper, but like beta particles, they can be especially harmful if they are ingested into the human body.

When certain processes in a nuclear reactor are faulty, a nuclear meltdown occurs and radioactive materials can be leaked into surrounding areas.

In the case of the 1959 meltdown at the Santa Susana Field Laboratory, the report states, it is believed that large amounts of Iodine-131 and Cesium-137 were released into nearby communities.

Doty said he doesn't believe the meltdown was as serious as some reports have made people to believe.

"There are two kinds of meltdowns: one that occurs in the secondary loop, and one that occurs in the primary loop-which is much more serious--and the study referred to a primary loop meltdown. I'm not sure that occurred," Doty said. "If it had, Rocketdyne could not have hid it. There's no way. It's not something you could hide.

"People have been over that area and they detect trace amounts, not the levels associated with a primary loop meltdown," he said. "I don't think it was as big as people want to make it sound."

Nevertheless, Doty said, Iodine-131 and Cesium-137 are both dangerous radiationemitting materials that produce both gamma rays and beta particles, even in trace amounts.

As materials release radiation, they also begin to decay. The average amount of time it takes for half of the atoms in radioactive material to decay is known as its half life.

"When you say there is a half life of one week, on the average, half the atoms will be there one week later, and then half of the half the following week," Doty said.

Cesium-137 is a greater threat to the general public because it has a much longer half-life when compared to Iodine-131, 30 years versus eight days, meaning it stays in the ground much longer.

Still, Doty said, tests at the field laboratory have never revealed anything more than trace amounts.

"If the Cesium is in the ground, it's not hiding. It is easily detectable," Doty said.

Iodine-131 is known to cause human thyroid cancer, while Cesium137 can cause cancer anywhere in the body.

"(Cesium-137) is the bad stuff," Doty said. "It works itself into the body and the bones and there's a chance it can lead to cancer."

Radiation typically interacts with the body in two ways: prompt interaction and small dose interaction. Prompt interaction occurs when someone is exposed to a very large dose of radiation, wiping out the immune system.

"When this happens, you can be killed by something as simple as herpes simplex," Doty said.

Small dose radiation is more common, but less is known about its effects.

This type of exposure occurs when a small amount of radioactive material is ingested into the body. It might do little to no damage at the time of ingestion, but tissue that is affected by the radiation can easily transform into a tumor 20 years later, according to Doty.

"We're just really beginning to understand the effects of this type of radiation because of the data from the Hiroshima and Nagasaki bombings," Doty said. "To truly understand the effects, you have to look at second and third generations because mutations from radiation can be passed down."

Ironically, the material that causes these harmful tissue mutations is also used for medical purposes. Iodine-131 is used to treat thyroid disorders, and materials that emit gamma rays and Xrays are used to diagnose broken bones and internal injuries. Alpha particles are also the key ingredient in the operation of smoke detectors. Radiation is a fact of life, and

it has many beneficial applications when used properly. But when it is introduced into the environment in large doses, it can be a threat to the health and safety of all things living in an area.

"Anywhere you try to escape to, radiation will be there," Doty said. "We've had documented cases of cancer for over 400 years and some of this might be induced by the natural radiation we find in this world. But it's important to understand that radiation is a relative danger."