So rapidly has cocaine become the "drug of choice" among Americans that last year it surpassed marijuana for the first time as the largest producer of illicit income in the United States--and by a huge margin.

The growth in cocaine use in the last three or four years is so dramatic that street sales of the drug may have reached $35 billion last year, outselling marijuana by $11 billion, according to Drug Enforcement Administration estimates.

"There has been an explosive increase in the use of cocaine by Americans in the last few years," says Dr. William Pollin, director of the National Institute on Drug Abuse. "Even though cocaine is not physiologically addicting, I find this a very dangerous increase because we're talking about a drug that may be the most seductive, intense and threatening drug we know."

So far this year, DEA sees no reason cocaine street sales will not set another record. Every estimate the agency has made of cocaine production in South America and of U.S. consumption based on seizures, arrests and emergency room admissions suggests that cocaine sales and usage are higher in 1981 than they were last year.

"We estimate that as much as 50 metric tons of cocaine were brought illegally into the U.S. last year," DEA spokesman David Hoover said. "We think it's running a little more this year." A metric ton is 2,204 pounds.

In addition to the implications for crime, cocaine appears to be deceptively harmless. In fact, it can be almost as dangerous as heroin, according to drug experts, and can cause paranoia, hallucination, and manic-depressive reaction.

While most doctors who deal with dangerous drugs refrain from describing cocaine use in the country today as an epidemic, many compare it with the turn-of-the-century "cocaine epidemic" in Europe. Then, cocaine use was rampant in the professional classes, with much of the European middle class and even in the working class involved. Many turn-of-the-century European doctors, including Sigmund Freud, were heavy cocaine users.

"We're in the formative stage where we're still not dealing with large segments of the population," said Dr. Everett Ellinwood, a Duke University School of Medicine psychiatrist and pharmacologist who is an expert on drug abuse. "Once the epidemic hit at the turn of the century, it marched right down through the population."

What worries pharmacologists like Ellinwood is that many users consider cocaine a drug whose "rush" or "high" rewards the body instead of punishing it. Users point out that cocaine doesn't put them to sleep, keep them awake, leave them with a hangover or addict them. It doesn't smell, cause speech to suffer or trigger a change in walk or performance.

It apparently has no social stigma. If anything, it has the social approval of the same people who might disapprove of marijuana or a stimulant like benzedrine.

"A lot of people look at cocaine and think that the use of it has no consequences, you don't have to pay the devil his due," Ellinwood said. "We're talking about the Mercedes-Benz of the drug business."

What concerns Ellinwood most is that cocaine users are convinced the drug is harmless. But to hear Ellinwood tell it, cocaine use in high enough doses and frequently enough can be just as harmful as benzedrine and almost as harmful as heroin.

"You can develop paranoia, deep-seated suspicion and then go into hallucinations, delusions of grandeur and manic depression," Ellinwood said. "A strong enough dose can make you psychotic and an overdose can kill you."

Recent statistics back this up. In 1980, hospital emergency rooms took in more than 4,000 persons suffering from cocaine overdose. Also in 1980, medical examiners in the nation's major cities reported 61 deaths from cocaine overdose and 205 deaths of people who had overdosed on a combination of cocaine and some other drug like heroin.

At least 10 cocaine fatalities were smugglers who tried to bring the drug into the United States in balloons they had swallowed. The powdered acid used to preserve the cocaine ate through the balloons and exploded the drug in their stomachs, causing almost instant death.

Conventional users of cocaine "snort" it through the nose but more and more are injecting it into their veins, smoking it in its pure powder form in what is called "freebase," using it with other drugs like heroin and giving themselves cocaine enemas to heighten the "high" they get from cocaine.

"Injecting cocaine is dangerous enough but smoking it is the most dangerous way to use it," said Dr. John Grabowsky of the National Institute on Drug Abuse. "Injecting it gets cocaine into the brain in 14 seconds. Smoking it gets it there in half that time."

Like a stiff dose of adrenalin, cocaine puts the body into the equivalent of a state of emergency. How it does that is something of a medical puzzle but doctors think it activates neurotransmitters in the brain that release large amounts of a brain chemical called dopamine, which exerts a strong stimulus on the body's motor system.

"Cocaine acts on the brain for no longer than an hour but is very intense while it's working," Ellinwood said. "You also get a very quick reinforcing effect with a second dose of cocaine that you don't get with other stimulants like benzedrine."

Ellinwood said the recent outbreak of cocaine use is a little like the surge of amphetamine use in the '60s but also a little different. He explained: "A lot of people began using amphetamines out of some business ethic, to work hard and keep moving, to stay awake while others were relaxing, eating or sleeping. Coke, on the other hand, is a status drug. It's not to work harder, it's almost an exotic way of showing off."

While it's triggering the brain cells that fire off dopamine, cocaine is flooding the cerebral cortex, which governs memory and reasoning, the hypothalamus, which controls appetite, body temperature and sleep, and the cerebellum, which regulates motion, walking and body balance. The result is what the University of Michigan pharmacologist Maurice Seevers called "the most pleasant experience" he'd ever encountered.

"He tried cocaine once and that was enough," Ellinwood said of the late Dr. Seevers. "He said it was too seductive."

The trouble with cocaine is, it's so seductive that it makes the user want more even while it's not technically addictive. Tests with monkeys have shown that they prefer cocaine to food to the point of starving themselves to get the cocaine. Several monkeys died at the University of Chicago from self-administered overdoses of cocaine because they simply couldn't get enough of the drug.

"We don't think this has anything to do with the rewarding effects of the drug," NIDA's Dr. Grabowsky said. "We believe it's from the drug's peculiar reinforcing effect that makes the experience stronger with each successive dose."

However it works, the consequences of prolonged cocaine use are inevitable, doctors said. "Like an overburdened telephone switchboard, the brain cannot handle all the messages," said Dr. Walter Riker Jr., chief of pharmacology at New York Hospital. "There is too much information coming in and the user becomes hyper-aroused. It's like a fire in the brain."

With higher doses and more frequent use, the alertness and exhiliration so strongly identified with cocaine can turn from insomnia to cocaine psychosis. Cocaine overusers have turned up in emergency rooms suspicious of everybody and thinking they were being persecuted by hospital technicians. Paranoia is a prize symptom of cocaine overuse. One user told her doctor she read Time magazine with a magnifying glass because there were messages for her printed in tiny print above the words.

One of the worst effects of cocaine overuse is that the user turns into a recluse no longer interested in anything but the drug. One psychiatrist reported treating a patient who retreated alone to his beach house every weekend to use $10,000 worth of cocaine by himself. There are many reports of users leaving their wives, their families and their jobs for their cocaine.

The jobs they leave are generally well-paying because cocaine sells for $100 a gram and $1,500 an ounce, almost three times as much as gold. Its price is one reason there is not a cocaine epidemic. Not everybody can afford it.

Those who can often go overboard. One movie director is said to spend $300,000 a year on the drug. One Florida psychiatrist said he is treating 10 victims of cocaine overdose whose habit cost them between $10,000 and $20,000 a week.

Despite its expense, cocaine use is on the rise. One measure is the number of arrests for cocaine possession by DEA agents in the last few years. DEA arrests for cocaine have gone from 1,580 in fiscal 1977 to 2,088 in 1978, 2,502 in 1979 and 3,148 a year ago. Another measurement is the surveys of youthful drug use by the National Institute on Drug Abuse.

"When we took our first survey of high school seniors in 1975, 6 percent said they'd used cocaine," NIDA Director Pollin said. "When we took our next survey in 1979, 12 percent said they had used it."

Nobody knows how many Americans regularly use cocaine, but the numbers are growing. More and more is being smuggled into the United States every year from Peru, Bolivia and Colombia where almost 100 percent of the world's cocaine is grown on the east side of the Andes Mountains.

With the price of cocaine so high, the smugglers try every method to get it into the United States. They impregnate it in their clothes, make plaster statues out of it and mix it in with the dirt holding carnation shipments from South America. Once, a man was caught smuggling cocaine that had been dissolved in expensive French red wine; but his partner tipped off the DEA. Dissolved (and recoverable) in the wine was almost $1 million in cocaine.