ON THE EDGE : THE ENIGMA OF SUICIDE, <i> By George Howe Colt (Summit Books: $24.95; 561 pp.)</i>

The figures are quite simply staggering. In 1987, the last year for which data is available, 30,796 Americans--or approximately half again as many as are murdered during any given 12 months--took their own lives. On an average day, about 1,000 people kill themselves worldwide. Since the 1950s, the adolescent suicide rate in the United States has climbed 300%.

The numbers, however, tell only the bare bones of the story. Invariably, every suicide is an excruciatingly human drama. In some cases--as with a gawky and withdrawn Westchester County, N.Y., teen-ager named Justin Spoonhour--the die was cast long before the deed was done. In others--as with a seemingly content Time Inc. graphic engineer named Peter Price or a young doctoral candidate named Carl whose wife adored him--the path that led to the final, fatal alternative was circuitous and marked by moments of great misgiving. And in still others--as with Fred and Holly Ishim, an aging Southern California couple who, fearing protracted, expensive deaths, joined the Hemlock Society--”self-delivery” was akin to a sacred rite.

Considering the mind-boggling frequency of the incidents of suicide, the pain that leads up to and results from each death and the intricate web of psychological, medical, legal, spiritual and philosophical issues that the act brings into relief, the literature on the topic--though extensive--is largely unsatisfying. While such classics as Karl Menninger’s “Man Against Himself,” Emile Durkheim’s “Suicide” and A. Alvarez’s “The Savage God” belong on any shelf devoted to the subject, heretofore no one had undertaken a definitive volume. Now, with the publication of George Howe Colt’s “The Enigma of Suicide,” that void has been filled.

In 1983, Colt, a staff writer at Life magazine, was assigned a piece on the so-called “Westchester cluster,” an epidemic during which eight adolescents living in the New York City suburbs took their lives in the space of only four months. From this seed grew “The Enigma of Suicide,” a work that in almost every way is a great and moving triumph.

For one thing, the reportage is stunning in its breadth and detail. Indeed, Colt covers everything from the therapeutic profession’s failure to deal with suicide-prone patients to the politics behind the city of San Francisco’s refusal to install higher railings along the walkways crossing the Golden Gate Bridge, a suicide mecca, to peculiar methods of self-destruction, among them swallowing spiders and firecrackers.

Yet Colt is no mere collector of unrelated facts. To the contrary, he always remains aware of historical context, traversing the ages to reveal how primitive cultures, the Greeks and Romans, early Christians, European rationalists like Voltaire and Rousseau, and such relative contemporaries as Freud, regarded suicide.

What finally makes this book so impressive, though, are the scrupulously documented, intimate narratives that Colt reconstructs that in a sense bring back to life a half-dozen suicide victims and allow us to see how their worlds closed in on them.

Who among us has not at one time known a Justin Spoonhour, an outcast, a butt of all jokes, the lonely, nervous boy who retreats further into himself with each rejection? And who has not known a Peter Price--someone Colt compares to Richard Cory, subject of the oft-anthologized Edwin A. Robinson poem who despite his riches and social graces “one calm summer night went home and put a bullet through his head”? And who has not known a Carl, a well-loved young man who--after discovering a flaw in the doctoral thesis he’d labored on for a decade--believed himself to be a failure and chose to put an end to his life?

Which brings us to the heart of Colt’s study, a question implicit in his title: Why does a person--barring affliction by terminal illness or strong cultural enforcement (hundreds of Japanese commit suicide annually after suffering business or political reversals, thus continuing the ancient Samurai tradition)--kill himself?

The answers are as numerous as there are types of therapy, but in Colt’s view, the most plausible theory is advanced by one R. E. Litman, author of several seminal works in the field of “Suicidology.” According to Litman, the mind can be seen as a kind of slot machine. While most of us suffer the periodic slings and arrows of outrageous fortune, rarely do such events happen all at once. In short, rarely do any of us hit what might be called the dark side of the jackpot, the “perverse, malevolent” alignment of psychological, sociological, biological and existential factors that when set off by a “triggering event” (the break-up of a marriage, a professional failure) can lead us to take our lives.

As Colt presents it, the most potent of these components are psychological and sociological. The early death of a parent, for instance, can spark a so called “morbid identification.” Then there is Freud’s notion that self-murder is in reality anger directed at another but exercised on oneself. Then there are the numerous cases in which poverty is a catalyst, although the low rate of suicides among American blacks--a fact that led comedian Dick Gregory to quip: “You can’t kill yourself by jumping out of the basement”--tends to undermine this argument.

But increasingly, biological explanations also are gaining credence. Of late, researchers have discovered that corpses of some suicides reveal abnormally low levels of a brain chemical called serotonin. In fact, a Swedish psychiatrist named Marie Asberg has proven that the lack of a chemical known as 5HIAA (a byproduct of serotonin) in spinal fluid can actually indicate a predisposition to suicide. While the time is far off before we’ll check our spinal fluid as we now check our car’s oil, the implication is clear: Suicide might be predictable and hence preventable.

Even now, there are many indications that suicidal individuals can be dissuaded from their self-destructive courses. Among the most fascinating parts of Colt’s book is one dealing with the two Los Angeles psychologists who in the late 1940s pioneered the suicide- prevention field. Working out of a room in the Brentwood Veterans Administration Hospital, Edwin Schneidman and Norman Farberow put together the first comprehensive study aimed at uncovering the motivating factors behind suicide.

What the men learned was that the stereotype holding that only psychotic or “crazy” people commit suicide was patently false. In fact, they discovered that just 15% of suicide victims were truly mad. Most were merely depressed. Furthermore, a majority of them were ambivalent about taking their lives. In Schneidman’s words, it’s possible for a person “to cut his throat and cry for help at the same time.”

Using their findings as a base, Schneidman and Farberow founded the Los Angeles Suicide Prevention Center in an old wing of County/USC Hospital in 1958, and, together, they inspired countless other crisis lines across America. Though Colt rightly points out that many of these hot lines lack standardized methods of treatment, his defense of their efficacy is a striking rebuttal to the libertarian notion that the suicidal should be left to their own devices.

Indeed, with typical reportorial aplomb, Colt adduces one startling fact that should end the debate altogether. Prior to 1963, the ovens in most English houses were fueled by a highly toxic gas derived from coal. In the past 18 years, almost all of these homes changed to less lethal natural gas. During this same time period, suicides in Great Britain involving gas dropped from 2,368 to 11, and the country’s overall suicide rate declined by one- third.

Again, though, statistics are not what one will ultimately take away from Colt’s remarkable work. (In fact, there are times when one wishes he’d have spared us from what can seem like an avalanche of figures and tautological assertions, i.e., television undermines family ties, ergo television contributes to the low self-esteem that contributes to suicide.)

Instead, Colt is at his finest--which is very fine indeed--when telling us how ordinary people can find themselves in despair. And he doesn’t do this in a sentimental fashion, in a manner that suggests easy solutions or follows party lines. One minute, he’s advancing a spirited defense of the Hemlock Society. The next he’s flaying two Parisian journalists whose 1982 how-to manual, “Suicide, Mode d’Emploi,” instigated a rash of suicides (15 deaths have so far been attributed to this irresponsible work).

Similarly, Colt leaves no doubt about the kind of emotional pain that usually precedes a suicide. For many victims, death seems the only means of surcease. Yet at the same time, in a poignant section on a Boston group that helps parents, husbands, wives and friends of suicide victims recover from what has to be the worst type of blow, he shows that the enduring pain felt by those left behind is nothing less than excruciating. Suicide is not a so-called victimless crime.

Early on in “The Enigma of Suicide,” Colt quotes Karl Menninger’s opinion that despite the efforts of many brilliant minds, “suicide is a durn mystery.” In the larger sense, this is still certainly so. But it is much less so now that we have Colt’s book.

Not that the work is perfect. The subject, in fact, is so immense that one can feel Colt struggling to get it all in. At times, the pace bogs down, and some passages are rough going. Yet these are picky caveats. Not only is this a masterly piece of journalism, it is also, strangely enough, a profoundly life-affirming study.