Growing up in Lakewood, N.J., Tim Stewart watched his dad nuke the lawn several times a year with synthetic fertilizers, weed-killers, and insecticides.

But as an adult, Stewart began to think of his own lawn as a drug addict in need of detox. He worried about his kids rolling around in it and about doing harm to the soil, air, and underground water. He even stressed over the potential danger to the family pets, Pluto the dog and Furball the hamster.

Stewart had stumbled upon the Great Lawn Dilemma, which poses a deceptively simple question: What's a safe and effective way to achieve a green lawn?

The answer sounds like former President Bill Clinton's ruminations on "what the meaning of the word is is": Depends on what you mean by safe and effective. Depends on what you consider green.

Even depends on your definition of lawn.

"It's a rat's nest," said Nancy Bosold, a lawn expert with the Pennsylvania State University's Cooperative Extension.

Make no mistake: Lawn and garden products are marketed as thoroughly tested, registered with the Environmental Protection Agency, and safe to use - with an important caveat:

If used properly.

"Most of us in the industry . . . work very hard and diligently trying to put together a product that's efficacious, easy to use, and has a minimal risk when used appropriately," said Bruce J. Augustin, chief agronomist for Scotts Miracle-Gro Co. in Marysville, Ohio, the nation's largest purveyor of lawn and garden products. Sales of its Scotts, Miracle-Gro, Ortho, and Roundup products approach $3 billion annually.

Sounds like a no-brainer, but even industry studies find most consumers don't follow directions.

"The general public doesn't even read the label," said Jane A. Hoppin, an environmental epidemiologist with the National Institute of Environmental Health Sciences.

According to the EPA, Americans use about 90 million pounds of pesticides a year on lawns and gardens, including weed-killing herbicides, insecticides for bugs, and fungicides for mold and mildew.

Studies link some of them to increased cancer risk, nervous-system injury, and possible damage to the lungs and reproductive, endocrine, and immune systems. Children and pets are especially vulnerable.

Thus, Hoppin's rule of thumb: "Anything that's toxic at some level you want to minimize your exposure to, because we don't know all the answers."

That's where Stewart found himself. As a cleanup contractor for toxic-waste sites, he'd seen "neon puddles and purple dirt." He wanted to minimize even minimal risk for his family.

So for the last five years, Stewart; his wife, Leslie; daughter Kylene, 7; son Jack, 23 months; and their pets have enjoyed a thick, green, all-organic lawn at their home in Lanoka Harbor at the Jersey Shore.

Many organic lawn products are on the market, including Scotts' Organic Choice line, but Stewart has his own recipe.

Twice a year, he applies corn gluten meal, a nontoxic by-product of corn syrup that contains about 10 percent nitrogen. It kills weeds before they sprout and fertilizes the lawn, making it a natural "weed and feed" product. He adds homemade compost, mows the lawn three inches high to prevent weeds from getting sun, and doesn't mind white clover, which naturally adds nitrogen to the soil.

But products labeled "organic" or "natural" aren't always risk-free, according to Jeff Gillman, author of The Truth About Organic Gardening: Benefits, Drawbacks, and the Bottom Line. For example, rotenone, an organic insecticide derived from tropical plants, and pyrethrum, which comes from chrysanthemums, can harm wildlife and people. Cocoa-bean hulls and bone and blood meal, all used as organic fertilizers, also have issues.

Gillman, a horticulturist and entomologist who grew up in Pughtown, teaches pesticide use and nursery management at the University of Minnesota. He leans toward organics but is comfortable using conventional products - the minimum amount, applied as directed, once every year or two, rather than four or five times a year, as lawn-care companies recommend.

"I think the problem is that we all love this perfect green lawn with no weeds," Gillman said, but such perfection requires frequent watering and a lot of fertilizers and pesticides.

Considering there are about 80 million lawns in the United States, that's a lot of stuff on the lawn. But as the experts like to say, "Dose makes the poison."

"All of these compounds have toxic properties if the exposure is sufficiently large," said Ted Schettler of Ann Arbor, Mich., science director of the nonprofit Science and Environmental Health Network. He cites "windows of vulnerability for child development, where even lower levels of exposure that have no impact for adults can have impacts on kids."

But lower doses add up. In 2006, a Harvard School of Public Health study concluded that chronic, low-dose exposure to pesticides resulted in a 70 percent higher incidence of Parkinson's disease. For study subjects who weren't farmers or ranchers, researchers said, this was likely due to pesticides used inside or outside the home.

Among herbicides, 2,4-D is the most widely used in the world, number three in the United States, where it's usually combined with fertilizer in "weed and feed" products. One of two active ingredients in Agent Orange, the Vietnam War-era defoliant, 2,4-D zaps a lawn's broadleaf weeds, such as dandelions and thistle.

According to the EPA, exposure to high concentrations can affect the central nervous system; other studies suggest a possible cancer link in humans and a heightened risk of malignant lymphoma in dogs.

But not everyone agrees, and 2,4-D remains highly controversial.

Scotts' Augustin, a turfgrass physiologist, calls 2,4-D "possibly the most extensively researched of all pesticides." When used correctly for approved uses, he said, 2,4-D is "low in toxicity to humans and animals."

Lisa A. Murphy, assistant professor of toxicology at the University of Pennsylvania School of Veterinary Medicine, believes, with those same caveats, "weed and feeds" will not harm pets. "When people have problems with pets and lawn chemicals, it's usually because the products haven't been used correctly," she said.

Pets who eat or roll in just-treated grass, then lick their paws or groom themselves, can develop short-term problems like drooling, vomiting, and diarrhea. "But the risk of significant problems is extremely low," said Murphy, who uses conventional lawn products herself.

Paul Tukey of New Gloucester, Maine, used to apply those products in his lawn-care service, but gave it up after a diagnosis of acute pesticide poisoning in 1993. The founder of SafeLawns.org and author of The Organic Lawn Care Manual, he has visited 41 states in a crusade to "get American lawns off drugs."

In this, he said, Canada is leading the way. In 2001, its Supreme Court ruled that municipalities can restrict cosmetic pesticide use on public and private property. Since then, more than 120 have done so.

But, Tukey said, the Great Lawn Debate "is still very much a debate. People are still saying, 'How dare they take away my ability to get rid of dandelions?' "

Several U.S. communities limit pesticide use around schools and day-care centers and on public property. About 30 New Jersey towns, including Voorhees and Cherry Hill, have designated their parks "pesticide-free zones."

Those outside the zones still have a choice.

"Weigh the benefits and risks," advised Sharon Gwaltney-Brant, medical director of the ASPCA's Animal Poison Control Center in Urbana, Ill., "but bottom line: No one's putting a gun to your head insisting you use chemicals on your lawn."

Contact staff writer Virginia A. Smith at 215-854-5720 or vsmith@phillynews.com.