EAST RUTHERFORD, N.J. -- Suiting up for the first practice of the season on their home field Thursday, the New York Giants strapped on their shinguards, their shoulder and rib pads, their helmets -- and their respirators.

It was a touch of black humor to lighten the mood in the locker room of last year's Superbowl champions. Last week, tackle Karl Nelson became the fourth Giant in seven years to contract cancer, representing an unusually high rate for a small number of athletes at the peak of their physical powers. Perceiving a connection among the illnesses and looking for a cause, some Giants pointed to the occupational hazards of the Meadowlands, the huge landfill where Giants Stadium is built.

"If there are radioactive or carcinogenic items buried in the stadium, obviously we are concerned," said strong safety Kenny Hill.

Inured to the constant violence of professional football, some Giants now anxiously question whether underground wastes expose them to hidden dangers by poisoning their playing field and the stadium's water, known for its foul odor and discoloration.

Their fears are dismissed by medical specialists as an irrational reaction fueled by New Jersey's widespread reputation as a home to pollutants. None of the four victims -- two of whom died -- played in Giants Stadium long enough to develop cancer from exposure to chemicals, they point out. And, while clusters of disease caused by environmental agents are normally of the same type, the Giants contracted four different strains of cancer. No chemical has been linked to Hodgkin's disease, which struck down Nelson, 27.

Moreover, samples of soil and water have never turned up toxic materials. Nor is the immediate area known for a high incidence of cancer.

"This is an unfortunate coincidence," said Dr. Frederick B. Cohen, chairman of the New Jersey Commission on Cancer Research. "But since New Jersey is the butt of every late-show comedian in the United States, it makes people think twice."

Still, four cancer cases on a team through which no more than 500 players have passed in seven years is considered high enough for cancer experts to suggest an epidemiological study and for the authority that runs the stadium to announce plans yesterday for environmental tests at the stadium grounds. The normal rate for a group of that size and age is less than one cancer, according to the American Cancer Society.

Of the earlier Giant casualties, linebacker Dan Lloyd, afflicted by lymphocyte lymphoma in 1980, recovered. But two running backs died -- Doug Kotar, of a brain tumor in 1983, and John Tuggle, of cancer of the blood vessels in 1986.

"A disproportionate number of us have gotten sick," said Hill, 29. "You have to ask if there's a connection between these occurrences and the environment."

The environment is the Meadowlands, a marshy wedge of northern New Jersey known for the past 100 years as a huge trash dump. Until 1970, about 2,500 acres of the low-lying land was covered by the industrial, commercial and residential wastes of 116 communities. Berry's Creek, which runs through the southeastern portion of the Meadowlands near the stadium, was an open sewer for mercury, arsenic and chromium used in the manufacturing processes of two now-defunct factories.

Along with the smelly industrial corridor of petrochemical companies and oil refineries south of New York City, the Meadowlands has helped secure the image of the Garden State as the Garbage State.

The state ranks sixth in the rate of cancer deaths nationwide. An unusual cancer cluster -- 12 leukemia cases and nine of Hodgkins disease -- was discovered in 1978 in the small town of Rutherford near the stadium. But state officials ruled out environment as a factor, and the incidence of cancer among the people who live and work in the Meadowlands is average, according to New Jersey's Deputy Health Commissioner Thomas Burke.

A special commission set up in 1969 to regulate development of the Meadowlands restricted garbage dumping to 300 acres and partially restored the ecology. Hundreds of businesses settled in the area, and by 1976, the jewel was in place -- the Meadowlands Sports Complex, consisting of the stadium and a racetrack and arena.

Esthetically, however, the Meadowlands hardly pleases. The sports complex is criss-crossed by congested highways and dotted by high radio towers and garbage piles as high as 150 feet.

This is the setting for the Giants, who play on the artificial turf of the 77,000-seat stadium from September to January, scrimmaging five times weekly on a natural turf field. It is a setting that inspired veteran linebacker Harry Carson to figure in "hazard pay" in the last contract he signed.

"The towers, the landfills, the pollution, that's the environment," he told The New York Daily News. "It's a reason I don't participate in the off-season conditioning program at the stadium. I don't think it's healthy to spend any more time there than I have to."

More pointed complaints surfaced after Nelson's diagnosis. The water in locker room showers was said to be malodorous, sometimes yellow, sometimes green. A coach, noticing a sticky black substance on the floor of the weight room, declared he was "alarmed" and demanded that it be tested. The "black goo," as it was called, was traced to astroturf that once served as floor covering.

"Hysteria is a good word," said Giants General Manager George Young of the cancer scare. "There's not one piece of evidence here; zippo."

Water serving the stadium is drawn from a protected watershed of the Hackensack River at least 10 miles from the Meadowlands. It also serves the region's homes and businesses, including 10 hospitals, and is tested monthly. A spokesman for the state Department of Environmental Protection called it "A-Okay."

To suggestions that players may be exposed to cancer-causing chemicals in the practice field dirt, the New Jersey Sports and Exposition Authority, which owns and operates the complex, noted that the landfill on which the stadium was built was dug out and replaced by 3.5 million cubic yards of ocean sand.

"I never heard of any way you can roll in the dirt and get cancer," said Cohen, who thinks a better explanation for the four illnesses may be the drugs pro football players take to kill pain and build strength.

Without clear-cut answers, Meadowlands loyalists blame the New York news media for whipping up hysteria to avenge the loss of the Giants and New York Jets (who have been playing in the stadium for three years) to New Jersey.

"It's the journalistic equivalent of shouting fire in a crowded theater," said Paul Wolcott, spokesman for the sports authority.