Dateline NBC exposed how unsafe practices in the booming dietary supplements industry - and lax government regulation - are allowing poisonous products to reach store shelves. Digging deep into government records, product recalls, criminal counterfeiting cases, plus state and federal civil court files, Dateline documented actual examples of dangerous products and falsified test results. In one case, workers at U.S. supplement maker used five-gallon buckets and women's pantyhose in an attempt to filter suspicious black flecks out of a liquid vitamin supplement bound for retail stores - including GNC. Dateline's investigation didn't stop at reviewing records. In a hidden camera sting, Dateline exposed so-called “dry-labbing” - the practice of certifying products without really testing them. Dateline set up its own supplement company, created sample products, deliberately spiked them with poisons, and then hired labs to test them. One lab specializing in supplements missed every poison - and told correspondent Chris Hansen the dangerous products were safe to sell. In spite of these documented threats to public health, federal officials acknowledged that labs that test dietary supplements are neither licensed nor inspected.