DAVID NELSON'S office is in South Salt Lake, in a building so nondescript you could easily miss it the first time around the block. His environmental consulting company, EnviroSearch, keeps such a low profile that the phone book doesn't even list its name right.

But in newly industrialized countries - where the environmental costs of industrialization are becoming more and more apparent - government officials and manufacturers keep Dave Nelson's fax number in their Rolodexes.Vietnam keeps in touch. So do the governments of Thailand and China and Singapore and Czechoslovakia, all of them wanting Nelson's advice about how to clean up the toxic chemicals that pollute their water and air.

The more he travels around the world, says Nelson, the more he realizes that Americans can't escape the effects of hazardous waste halfway around the globe - and they can't escape being part of the problem either.

Nelson turns on a slide projector and clicks it until he finds the picture he wants: a concrete building in Hong Kong housing a fabric-dyeing factory. You can tell which floor the factory is on because just below the windows the walls are stained black.

"You can imagine the conditions inside," says Nelson. "The chemicals have eroded the enamel off the workers' teeth."

He clicks to another slide: another concrete building in Hong Kong that houses yet another fabric dyeing factory. Inside, workers take big rolls of denim and run it through acids and hot dyes to make acid-wash jeans.

Acid-wash jeans were big fashion news a year or so ago. It's doubtful, though, that Utahns who bought them off the racks of ZCMI or Mervyn's gave much thought to what the acid really was, or how the factory got rid of it.

But Nelson has a picture of that, too: a canal full of hot poisons steaming through the streets of Hong Kong. Eventually the acids wind up in the ocean, then in the fish, and eventually some of that fish is exported to the West, where people in acid-wash jeans eat it for dinner. It's a small world.

In other countries, too, throughout Southeast Asia and Eastern Europe - where pollution controls have not kept up with increasing industrialization - toxic chemicals are wreaking havoc:

- In Vietnam, chemicals left over from the war continue to haunt the country. Solvents and gasoline dumped by Americans, pesticide residues from Agent Orange, plus current industrial waste and herbicides, combine to make Vietnam's food chain the most contaminated in the world, says Nelson.

- In Singapore, new high-rises have been abandoned after air pollution eroded the metal bolts that held them together.

- In Taiwan, in Salt Lake City's sister city, Kee Lung, heavy metals from a silver mine drain into what once were the richest fisheries in the world.

- In China, at least 2,000 people have died from groundwater contaminated by a chrome-plating process.

When he visits Asian countries - this week, for example, Nelson is in Taiwan and the Philippines giving workshops on hazardous wastes - he stresses that there are heavy environmental prices to pay for industrialization.

For all their emerging problems, however, newly industrialized countries still don't hold a candle to the United States when it comes to toxics. "Per capita, the U.S. generates more hazardous waste than anywhere," says Nelson.

"But we don't have the dead bodies," and that keeps Americans from understanding the urgency of the situation, he says. "The point is that nobody knows how bad the problem is."

There are now an estimated 65,000 chemicals available to keep Americans comfortable and trendy. Only 52 of them are known carcinogens. But according to the American Chemical Society, Nelson points out, only 2 percent of the 65,000 chemicals have been studied for their health effects.

What we do know, he says, is that disposing of toxic chemicals is costly and difficult. So far, of the potential 27,000 Environmental Protection Agency "Superfund" hazardous-waste sites, only 35 have actually been cleaned up.

Ironically, even when we think we're making headway environmentally, problems have a way of catching up with us, says Nelson. Many older recycling centers, for example, are hazardous-waste sites.

People always ask him, he says, how the world should get rid of its hazardous wastes. "I tell them, `You're asking the wrong question.' The answer is not to generate it in the first place.

"There needs to be a fundamental and dramatic shift in consumerism," he adds. "We need to consume less and produce less."

Consumers can have an impact, he says, by letting manufacturers know that they won't buy products for which there is a big environmental price tag.

"I know, from representing industry, that they are increasingly listening to" such concerns, he says. "My prediction is that industry will become its own watchdog, because of its own liability."

"Green labeling" - government-regulated product labeling that will list the environmental impact of all products sold in the United States - would also help, he says. Green labeling legislation will be introduced in Congress this year.

"I think we'll one day be able to say to our grandchildren: `We used to be able to buy the following products in the following colors.' " Shiny red cars, bright yellow plastic toys and fluorescent Rollerblades.

"And it will be seen as an anachronism."