WASHINGTON, D.C.: Although it sounds like a 19th Century cure-all, "Dr. Brown's Home Drug Testing System," a pre-packaged set of plastic tubes and a urine sample cup has won FDA approval as the first drug-testing kit for home use. Translation: parental use. While the $30 device, expected in the stores in about six weeks, may never "empower the individual citizen," as inventor Dr. Theodore Brown promises, its ability to detect cocaine, heroin, marijuana, PCP, amphetamines and morphine with a mail-in urine sample is bound to spark a storm of controversy. Customers need only place a urine sample in a plastic package included with the kit, mail it in to a government-certified laboratory, and, after one to three days, dial a 1-800 number with their identification code to learn the results. While Brown, a Maryland-based clinical psychologist experienced in substance abuse treatment, insists that the code will protect customers' anonymity, critics charge that confidentiality after the fact isnít the main issue. Privacy is the issue, when parents and schools confront children with demands for urine samples so that they can be tested for drug use. Moreover, professional testers say that idiosyncrasies in sampling time or diet could alter results seriously. Some herbal teas, for example, can give false indications of heroin use. Personal Health and Hygiene, the company formed by Brown to market his kit, maintains that all potential snafus will be explained and that all test results will be confirmed prior to release to customers. No word on what advice Brown will give parents trying to get their children to give up a urine sample.