Toxin is bestseller #20 for Robin Cook, the author who put the medical thriller on the bestseller map. His latest lands on our hardcover chart in the #6 spot, with more than 250,000 copies in print. Meanwhile, his earlier book, Chromosome 6, just published by Berkley, moves up to #4 on the mass market chart. First printing was 1,350,000 copies and a second trip to press brings the in-print total to 1.5 million. Cook is finishing a six-city tour and was also a recent keynote speaker at the Center for Disease Control in Atlanta.