The US Food and Drug Administration (FDA) has imposed an "import alert" on medications made in an Indian plant owned by drug maker Ranbaxy Laboratories after a black fiber identified as a human hair was found embedded in a tablet. Although 40% of the company's business is exports to the US, this particular factory's exports had been halted since last November, when it voluntarily recalled atorvastatin (generic Lipitor) found to have glass particles in certain batches. Substandard and even counterfeit medication is a growing problem, especially in lower income countries. In a review of 15 studies performed primarily in Africa and Asia, the prevalence of substandard or counterfeit medications was 28%. The most common issue with these drugs was inadequate amounts of active ingredients.