THE two young Thai men couldn't be more different. The older one, Somsak, is an uneducated farm worker from Loei Province. The younger, Boonlert, is a high school student from Bangkok, the son of a prosperous merchant.
Somsak follows the mango, tamarind, and sugar-cane crops in several northern provinces, earning a meager living performing backbreaking labor. Meanwhile, Boonlert plays hooky from school.
They are just two examples of a rapidly growing number of substance abusers in Thailand, a trend that threatens to undermine the economy.
Rapid changes brought on by the booming Thai economy in the past 10 years have begun to leave ugly marks on usually smiling and serene Thai faces. Traditional institutions such as the school, home, family, and Buddhist religion seem to be under siege from pressures placed on them by new and different economic demands.
Many look for help to ya mah (horse medicine), the Thai name for amphetamine tablets (they are said to make the user feel as strong as a horse). Both Somsak and Boonlert are confirmed amphetamine addicts undergoing rehabilitation treatment in Bang-kok.
''I started taking ya mah from watching friends ... on plantations,'' says Somsak, whose marriage has collapsed because of his long absence from home while undergoing rehabilitation. ''But I know of cases of sugar-cane plantations where the foreman puts it in the water.''
''Workers know it's dangerous to use amphetamines,'' says Abha Sirivongs na Ayudhya, a researcher at the Social Research Institute of Chulalongkorn University, who just completed a report on amphetamine use among sugar-cane workers.
''But because they are under pressure to deliver the crop on time, they want to work longer, and so they use it. But they ask the same question: 'What will happen to me if I take it?' ''
''You can buy [ya mah] like candy - anywhere, anytime,'' says the Rev. Joe Maier, an American Roman Catholic clergyman known as ''the slum priest of Klong Toey,'' Bangkok's oldest and largest poor community, which surrounds the seamy river port. ''And even though the price has gone up from 60 baht [$2] to 120 baht [$5] per tablet,'' Fr. Maier says, ''the poor kids, students, or workers simply pool their money together and divide the pill up into four legs [parts].''
The Thailand Development Research Institute (TDRI) recently completed a study of narcotic use in Thailand, funded by the Narcotics Affairs Section of the US Embassy. The report set off an explosion of concern among Thai politicians, government officials, and police.
It concluded that there are at least 1.27 million narcotic addicts in Thailand, more than 2 percent of the population of 60 million. Glue and thinner sniffers and marijuana smokers head the list. Amphetamine users came in third at more than 300,000 users, and were one of the fastest-growing percentages. ''Thailand's central region plus Bangkok have the highest percentage of amphetamine users,'' says Nipon Poapongsakorn, director of the study, entitled Narcotics Addiction in Thailand, ''while the rural and poor population abuse more glue and thinner. It's cheaper.''
The most recent worrisome development has been the growing use of illicit stimulants filtering up the social and economic ladder to high school, university students, and affluent young people seeking recreational drugs. ''You can find amphetamines in every high school and university in Bangkok,'' Maier says, ''and usually high school and college kids are selling them to each other. One reason [ya mah] is in schools is because of more competition for university places. So you have to study more and stay awake longer. Remember, it's not bad children we are talking about but regular kids.''
THE Thai police have mounted public-awareness campaigns over the past few years, especially about the side effects of the drugs. But they are the first to say they have failed to stamp out drug abuse.
Maj. Gen. Poonsawat Lalap, commander of the Narcotics Suppression Bureau, says the police have arrested more than 15,000 people in 13,508 amphetamine-related cases and seized 6.3 million tablets, as well as 57.5 kilograms of the drug in its powdered form last year This year, the police say they have lost count of the number of tablets seized between January and September.
''There is a frightening phenomenon going on right now in Thailand. It amounts to a changing of the guard toward behavior that is the antithesis of Buddhist principles,'' Maier says. ''The little-known or talked-about part of the ya-mah story is that amphetamine use brings with it unheard of violence in this country - Thai against Thai.''
Increased Thai media attention has exerted pressure on the government. ''More people in government are talking about the need to address the growing use of stimulants,'' says Chawalit Yodmani, former secretary-general of the Thai Office of Narcotics Control Board. ''We see it as a loss of human resources and a negative impact on the economy.''
In reaction to the TDRI study, one member of parliament has called for the death penalty for amphetamine sellers and producers. The Bangkok chief of police has asked for longer jail sentences and stiffer penalties.
The TDRI study and the reaction of Thai officials has come under criticism from some medical experts.''Have you ever heard of these types of penalties working in other countries?'' asks Vichai Poshychindra, research specialist at the Institute of Health Research at Chulalongkorn University. ''Everything related to the results of substance abuse becomes an emotional reaction in Thailand.''
You have to distinguish between users, misusers, and addicts, Mr. Vichai says. He says researchers are not entirely sure that people really become addicted to amphetamines the way they do to other narcotics.
But Maier doesn't need much convincing. He says that kind of talk is ivory-tower nonsense. ''Just come to Klong Toey,'' he insists. ''I'll show you plenty of cases where a kid is wandering around babbling to himself not even knowing his own name. Of course they're addicted. The question is what is the government going to do about restricting the availability of illegal substances?''