NADVOITSY, Russia – The children of this town learn early not to smile.

When they do, they show a ghastly array of blackened, splintered, rotting stumps where milk-white teeth might have been.

An environmental plague has struck this northern land of lakes, no longer pristine, and thinning pine forests. The children of Nadvoitsy are its victims.

Their disease is caused by a pollutant that the town’s main employer, the Nadvoitsy Aluminum factory, dumped in its back yard for three decades. Slowly, the contaminant seeped more than a mile through the watery soil to the lake that supplies drinking water to almost all of the 19,000 residents of this little town near the Finnish border. In one of the many cruel ironies bred by environmental indifference in the former Soviet Union, the substance that has sickened an estimated 4,000 children in Nadvoitsy is massive quantities of fluoride. Because it is beneficial in small doses, no one ever bothered to check for its presence.

Then, for years after officials discovered the chemical culprit in the mid-1980s, townspeople continued to drink from the poisoned lake. Building a pipeline to a cleaner water source was deemed too expensive.

Dreadful as Nadvoitsy’s story is, its water woes are hardly unique. A new report from the Environment Ministry says half of Russia’s population is forced to rely on substandard drinking water.

Nadvoitsy’s polluters, chastened by the rage and sorrow of the townspeople, are at last committed to cleaning up — just when Russia’s economic tailspin makes it nearly impossible to raise the money to do so.

As this one-factory town and hundreds of other dangerously polluted Russian cities have discovered, environmental safety has become a casualty of the country’s economic chaos.

Forty-three Russian cities are in urgent need of air pollution relief, 1,016 plant and animal species are endangered, and deforestation is widespread, the World Bank reported recently.

Virtually nothing has been done to clean up the radioactive and toxic waste sites that pepper the country. And as a symbol of the environmental calamities here, even the most basic of human needs — clean drinking water — has been put on hold.

Alexei V. Yablokov, the father of Russia’s environmental movement, recently warned that the dreadful ecological legacy of the former Soviet Union has only been worsened by five years of economic decline.

Between 14% and 15% of Russian territory is so polluted that it is unsafe for habitation, but 40 million people live there anyway, Yablokov said.

It is not surprising that environmental problems are low on the agenda for a new Russian leadership that has been consumed by the simultaneous struggle to calm violent political strife at home, squelch ethnic fires near its borders, carry out fundamental economic reform and cope with a huge decline in the gross national product.

But while Moscow’s mind is elsewhere, ecologists say, Russia’s far-flung provinces are being ravaged by uncontrolled strip-mining, clear-cutting of forests and surreptitious dumping of hazardous wastes.

“The term ecocide is very appropriate,” Yablokov said.

When Russian authorities do catch environmental despoilers red-handed, they can mete out only puny punishment. Inflation has reduced to a pittance the maximum fines that polluters can be forced to pay.

For example, in 1993, Nadvoitsy Aluminum spewed out 8,640 tons of pollutants, including airborne fluoride. But it has paid just $3,500 in fines this quarter for exceeding pollution limits, said Valentin P. Kudryavtsev, the senior environmental inspector who has been tenaciously prodding the aluminum plant and its neighbors to clean up.

The government recently decided against raising the fines to keep up with inflation, saying to do so would create undue economic hardship, Kudryavtsev said.

Some eco-offenders remain as brazen as ever.

In June, a chemical plant in Khabarovsk dumped 1 1/2 tons of furfural, an oily liquid used to make disinfectants and preservatives, into the Khor River. Local officials said the toxin caused $45 million in environmental damage. The plant will be fined and ordered to clean up the river, but none of the managers responsible for the dumping was sacked.

Eight years after the Chernobyl nuclear accident demonstrated the folly of trying to cover up or ignore environmental catastrophe, Russian officials still have a tendency to do just that.

The massive Siberian oil spill that came to light last month began in August, but most Russians learned of it only after Americans blew the whistle. In fact, such oil and chemical spills are so common that they barely make news here. Nevertheless, they have steadily contaminated the nation’s water supplies.

As rivers in the former Soviet Union were befouled, planners began tapping underground aquifers for drinking water. Now, pollutants have seeped into these underground sources, especially in the intensely industrial European part of Russia, according to the Environment Ministry report. It found the quality of 80 aquifers that supply 60 cities with drinking water had worsened in 1993.

In the cities, aging water treatment plants are inadequately maintained, and authorities simply add more and more chlorine to dull the rising bacteria count. In the spring, Moscow’s tap water smells like a public swimming pool. Elsewhere, it often runs orange or brown.

Where there is industrial equipment to control water pollution, it is often obsolete and overburdened. The ministry found the percentage of industrial waste water that is treated at all declined in 1993, to 8.7% of the total outflow.

More than 20% of the drinking water samples the ministry studied in 1993 flunked biological or chemical purity tests, and 4.3% of samples contained such high bacterial counts as to pose “real epidemiological danger.” Overall, the report concluded that Russia’s drinking water problem is now critical and “has a dangerous tendency to deteriorate.”

In 1993, Russia spent about $19.25 per citizen on environmental protection, forestry, national park maintenance and wildlife protection. Of that, $2.28 was used for capital investments to protect water resources. Overall environmental spending has shrunk 20% since 1990.

Most Russians never know whether their water is safe to drink because authorities do not test for many of the most dangerous pollutants, said Alexander Knorre, who heads the Moscow office of Greenpeace.

For example, very few Russian laboratories have the sophisticated equipment needed to test for dioxin, a chemical used in paper production that is a proven carcinogen, Knorre said. The test can cost up to $300, so it is almost never performed, he said.

Upstream from Nadvoitsy is the huge Segezha paper plant, which almost surely emits dioxin. “If they can’t measure it, it’s not a problem,” Knorre said.

Russia’s economic calamity has somewhat slowed the pace of new pollution. A 25% slump in industrial production over the last eight months alone has meant fewer toxic gases spewing from factory smokestacks and fewer poisons flowing into rivers and streams.

The slump caused Russia’s 13 largest aluminum plants to release 13% fewer tons of air pollutants in 1993 than one year earlier. And biologists say the Volga River has become healthier since many of the huge chemical plants along its banks have shut down.

But these gains are illusory, ecologists warn. Fewer herbicides and pesticides are flowing into Russian waters only because cash-strapped farms cannot afford to buy them. When the economy improves, they say, factories will resume their lethal output.

The reckless disregard of the Siberian oil company Komineft, which continued to pump for two months while thousands of gallons of oil leaked into the watery tundra, shows that the Soviet-era priority for increasing industrial production at all costs has changed little, environmentalists say. Nature is still seen as inexhaustible and indestructible. Human health and safety have a relatively low value.

For years, Nadvoitsy officials brushed off warnings that the town water was not fit to drink, according to Kudryavtsev, an ecologist who was kicked out of one Communist Party meeting for insisting that a 24-mile pipeline must be built to provide the town with safe water.

“Our country is great at cosmonauts and weapons,” the ecologist said bitterly. “The leadership didn’t give a damn what kind of water we drank. You don’t understand how this could happen, but I tell you, it’s very simple: They just didn’t care.”

Officials also ignored the first cases of tooth disease, which began to appear in the 1970s as fluoride replaced the calcium in growing children’s teeth and bones. Deprived of calcium, victims do not develop tooth enamel, and their teeth darken and rot, doctors said.

Aluminum plant workers have very high rates of occupational illnesses, but adults who lived in the town were seemingly unaffected by the fluoride. It was not until the early 1980s, when more than three-quarters of the town’s children were suffering at least some symptoms of environmental disease, that officials began looking for a chemical culprit.

“Let God himself judge them,” said Yevgenia Misharina, a 16-year-old high school student who suffers from fluorosis. She has high cheekbones, wide-set blue eyes and an intoxicating grin. So many Nadvoitsy residents have bad teeth that nobody recoils at her smile. But in front of strangers, she tries to keep her lips closed over the wreckage inside.

Yevgenia and her friends say their joints often crack and ache in the morning, and they wonder what will happen to them as they age. They do not trust authorities who say their water is now safe to drink. They just want to grow up and move out of town as soon as possible.

“I don’t want my kids to have brown teeth and bad bones and be in and out of the hospital all the time,” said Anna Sidorova, 15.

Besides teeth and bone problems, Nadvoitsy’s children also suffer from unusually high rates of liver and kidney disease, chronic hepatitis and respiratory ailments, including pneumonia, said Tatyana V. Tarasyuk, chief physician at Nadvoitsy hospital. Tarasyuk suspects some of these ailments may be exacerbated, if not caused, by the high levels of environmental pollution.

Tarasyuk’s son also suffers from fluorosis. “It’s not a pretty sight when he laughs,” she said.

Nadvoitsy Aluminum officials have tried to make amends for the tragedy they admit they caused. At its own expense, the factory has dug up hundreds of yards of contaminated soil and sealed it in huge watertight pits to prevent more toxins from flowing into the lake. Gradually, the level of fluoride in the drinking water has returned to normal.

Using profits from aluminum exports, the factory also distributes free juice and vitamins to all the town’s children. It has built a modern dentist’s office with equipment from Germany and will cap the damaged teeth of any Nadvoitsy resident without charge. It is only a cosmetic fix — some teeth have crumbled so much that caps won’t hold — but one that has earned the factory tremendous goodwill.

The factory has also hired Houston-based Kaiser Aluminum to replace a small fraction of its 1954 vintage equipment with more efficient, less-polluting technology.

At its Tacoma, Wash., plant, Kaiser uses a dry-scrubbing system that recycles airborne fluoride and other pollutants right back into the production process and is offering the same technology to Nadvoitsy and other Russian aluminum plants, said Kaiser’s site manager, Richard Cable. But with inflation driving up Russian interest rates to 170% per year, the Nadvoitsy factory can little afford to borrow the huge sums needed to undo its toxic legacy.

“People understand that we are thinking of their welfare,” said Anatoly V. Bezrukov, the factory’s new director. “Maybe we can’t do everything all at once, but we’re trying. They understand.”

Ecologist Kudryavtsev said it is too soon to applaud. The factory’s airborne emissions are still so corrosive that plant windowpanes turn cloudy within a year of installation. Not a single pine tree grows within half a mile of its smokestacks, only anemic willows and low-lying shrubs.

“It’s the fluoride,” Kudryavtsev explained. “It kills the pine needles.”

And the toxic fallout continues. Last year, public health authorities told Nadvoitsy residents to stop eating green vegetables from their gardens after they discovered unacceptably high levels of fluoride in locally grown lettuce, parsley and dill.

Even today, more than a decade after the fluoride link was conclusively proven, 5% to 10% of kindergartners show symptoms of fluorosis, Tarasyuk said.

The townspeople continue to drink from the same lake. Nadvoitsy officials insist that the water is now safe, but Kaiser Aluminum did its own analysis and instructed its staff not to drink it.

Although the nearby Segezha paper plant has polluted many alternative water sources, there are local springs within driving distance where residents can draw clean water. But few bother.

“In the Russian character is a tendency not to take responsibility for his own health,” Kudryavtsev said. “You can tell him it’s better not to drink the water, better to boil it, but people will continue to drink it from the tap, as they always did. People think, ‘I’ll live as long as I live. It’s in God’s hands.’ ”

This attitude is reinforced by an unfortunate but widespread folk belief that any kind of pollution — even radioactivity and heavy metals — is washed out of the body by a good belt of vodka.

Briefly, in the late 1980s, an angry and powerful grass-roots ecology movement sprang up in Nadvoitsy, as happened across Russia in the aftermath of Chernobyl.

Today, the founder of Nadvoitsy’s green coalition has moved away in search of better medical care for her ailing child, and the ecology movement has all but died out.

Townspeople say they are grateful that the aluminum factory is still operating, offers high wages in exchange for the dangerous work and pays salaries on time.

“The factory is the only institution that helps us,” Tarasyuk said. “If there is no factory, there is no town.”