TEEN DRINKING. SOUTH - AND NORTH - OF THE BORDER. In Mexico. Greater attention and care needed for many of today's young Mexicans who are searching for identity.

THIRTEEN-year-old Valent'in Rodr'iguez rolled over on his side just before dawn in the Mexico City suburb of Netzahualcoyotl. For a few minutes Valent'in lay there, then slowly got to his feet and leaned against a scarred building wall to regain his sense of place and direction. Finally, he made his way along littered streets to the Netzahualcoyotl market to steal or beg a piece of fruit or bread before beginning his workday.

It is not the first time teen-ager Valentin has been drunk. He admits that he often drinks cana to relieve his hunger instead of eating.

He and an estimated 2 million Mexican youths under the age of 18 repeat the ordeal he has just been through almost every day.

Like many of them, Valent'in is often paid for his work in goods or alcohol instead of money. Also like many of them, he was brought to the city as a child by parents fleeing rural unemployment.

In Mexico City and its suburbs alone, the percentage of severe alcoholism among the population in general has tripled in the past seven years.

But according to authorities, among teen-agers the percentage has increased an alarming 2,000 percent!

The continuing breakup of many family units, particularly among immigrants from the provinces, thrusts many young males onto the streets to seek work where and when they can find it as ambulatory vendors, piece workers, or temporary laborers.

``They live day by day,'' reports Rafael Velasco Fern'andez, a psychologist.

``They project into the future no further than where they will get their evening cana [bootleg rum] and where they will spend the night.''

In the congested shantytowns and slums that surround most of Mexico's major cities, drinking begins before dawn, when ``quasi legal'' toreos start selling cana and pulque to men heading out to work in produce, construction, or other laboring jobs.

``Many of those who do not work, including teen-age and preteen-age boys,'' explains National University of Mexico economist Bernardo Navarro Ben'itez, ``spend the day drinking in order to mask the fact of their unemployment.''

To be drunk while others are working defies the social standard, and some youths consider defying standards proof of their masculinity.

``The harder the life in poor city barrios like Netzahualcoyotl becomes, the more prevalent the alcoholism,'' says Mr. Navarro Ben'itez.

By getting drunk, residents try to temporarily forget both their deprivations and the difficulties they have earning a living.

``They achieve the illusion, if not the fact, of getting outside themselves in the companionship of others,'' says social expert Francisco Turull Torres.

Indeed, the indigenous Mexican Indian tribes believe that the soul leaves the body during drunkenness to unite with the souls of other inebriates and returns with sobriety.

Vestiges of these beliefs prevail in the poor barrios.

Some believe that ``to get drunk,'' says Mr. Ra'ul Hernandez, a folklorist, ``is to go to a better world.''

Mexican sociologists lament the incredible toll that alcoholism takes on the youth of the country. ``Two million teen-agers have grown old before their time,'' says Velasco Fernandez, a Mexican social observer.

``They have been denied education, health, and childhoods. They scramble for sustenance from the time they are 8 or 9 in barrios that offer neither assistance, employment, nor values.

``Those who do not become criminals slip into the patterns of those around them and lose all hope for happiness and health.''

A National University study shows that more than 50 percent of the meager incomes achieved by residents of a poor barrio in Guadalajara is spent on alcoholic beverages, most of which are brewed and sold illegally.

The migration of campesinos and residents of rural Mexico to the cities has increased dramatically during the past decade. Already-strained public services are able to assist ``only the desperately ill and some victims of crime,'' a government Secretary of Health and Public Assistance report in 1985 revealed.

Claudia Selser Ventura, a psychologist with the Latin American Institute of Transnational Studies, attributes part of the increase in teen-age alcoholism and peer acceptance of it to television, newspaper, and billboard advertising.

``The ads link drinking to happiness and sexual and athletic success,'' she comments.

``They encourage the notion that some kind of magic occurs after one has consumed this or that brand of beer or brandy or rum.''

Abandoned without family, many a teen is forced to compete for employment with thousands like him for hourly or daily jobs loading trucks, carrying wood or charcoal, cleaning oil cans, or clearing construction debris. He gets paid only a few coins, or food, or cana.

He's often insulted and cheated by those who hire him and lives in an environment where prostitutes sometimes charge less than restaurants do and mashed corn scraped out of a paper cup may be considered a daily meal.

``In pre-Columbian times,'' notes sociologist Laura D'iaz Leal, ``the Indian drank to transcend the present. Today he drinks to forget the present.''

This is an issue drawing more and more attention of government officials and social workers.

And the need so far has been this increased sensitization of the nation's authorities.

Now the next step is solutions.