Fine environmental reporting from the Third World front lines. Mexico, notes Pacific News Service editor Simon, ``is the third most biologically diverse nation on the planet,'' the home of countless animal and plant species found nowhere else. Given current international concerns for biodiversity and habitat preservation, he argues that this vast biological cornucopia must be saved from further destruction; yet, in one case study after another, he shows that those international concerns have consistently been brushed aside by a succession of corrupt governments. Some of Mexico's problems are well known, notably that of air pollution in the major cities. Simon adds a personal note as a resident of the capital, where on windless days ``ten thousand tons of toxic gunk'' stall in midair to choke Mexico City's 20 million residents--gunk, Simon notes, that is made up not only of the normal car exhaust and other airborne industrial particulates, but also of blowing dirt from deforested hillsides, to say nothing of dried fecal dust stirred up from the city's innumerable outhouses. But many of Mexico's most pressing problems are less well known, and Simon performs a valuable service by cataloging them in close detail. Among them are the continuing destruction of farmland through overgrazing and improper agricultural practices; the depletion of supplies of potable water; and the devastation of old-growth forests (the Sierra Madre of Mexico is now, Simon writes, the scene of ``the highest rate of deforestation in the world''). Unless something is done to relieve the assault on Mexico's environment, Simon suggests, that nation's growing population will continue to seek routes of escape to safer, cleaner places--the US first among them. This sobering book is required reading for environmentalists, both critics and supporters of NAFTA, and all readers who care for Mexico's future.