Up in Smoke

When EW last saw Eric Schlosser, he was heading out of a Manhattan McDonald's, somewhat amazed that anyone was interested in writing about ''Fast Food Nation.'' Two years later, that look at ''the dark side of the all-American meal'' is still selling like Big Macs, and its author is back with more investigative journalism. In ''Reefer Madness: Sex, Drugs, and Cheap Labor in the American Black Market,'' Schlosser, 43, untangles the complicated histories of three pillars of America's underground economy: pot, pornography, and illegal migrant workers. And though the author has doggedly interviewed drug czars and smut kings, he still can't tell you exactly how big that economy is. But, he believes, ''it's totally plausible that it's 9 to 10 percent of our GNP.'' Schlosser says that this book, like his last, is ''about the history of America that's not being talked about proudly.'' (May)