David Nelson was attending an environmental conference in Hawaii a couple of years ago when the chairman approached him and said he had a favor to ask. Nelson was a relative newcomer to the international environmental scene, so he had a pretty good idea what the favor would be.

"I was sure he was going to ask me to run the slide projector."Instead, Nelson was asked to head up the first international conference on hazardous waste. "We selected you because of your undying interest" in toxic chemicals, the chairman told him.

And they didn't even know that, for Nelson, a trip to the beach isn't really exciting unless he can spot medical waste floating up on shore.

Some people, in fact, have called him a zealot. In the early '80s, Nelson made headlines and enemies when, as a Salt Lake City-County health inspector, he led the department's assault on hazardous-chemical sites such as Sharon Steel and Portland Cement. He also focused attention on asbestos clean-up.

Instead of being praised for his efforts, Nelson was given a new assignment: food inspector. It was then that he quit to form his own environmental consulting company.

Now, in addition to advising foreign governments, Nelson consults with some of the same companies he policed as a health department regulator. Environmental purists tell him he's sold out, but Nelson sees it differently:

"Environmental consultants help industry comply (with regulations) where otherwise they might not," he says.

He finds fault with environmentalists who refuse to see the complexities of cleaning up the world.

There are cultural and religious differences, for example, that complicate good intentions. In some parts of Southeast Asia, when Nelson speaks to rural workers about the carcinogenic effects of toxics, the exchange might go something like this:

"You might get cancer," Nelson will tell them.

"Where do you die when you get cancer?" they want to know.

"Oh, it's a painful, lingering death. You probably would die at home."

"Home. Then you'd be surrounded by your family. That's good."

People need to understand, says Nelson, that "Ban Toxic Waste" is too simplistic a slogan. Especially, he says, when the people who say it also drive cars, work in air-conditioned offices and buy the thousands of products made with the very chemicals they want banned.

Examples are everywhere you look, says Nelson, who points to the shiny buckle on his wrist watch - it was likely electroplated in a little factory in Hong Kong, where chrome, nickel and other heavy metals used in the electroplating process were then dumped into waterways and eventually found their way into the food chain.