Vaping and E-cigrettes are becoming a serious problem according to the Food and Drug Administration. The government organization has opened a criminal investigation into a wave of more than 530 reported illness that came as a result of vaping. According to Politico, the director of the Centers for Disease Control is “very concerned” about the sharp increase in vaping-related illnesses.

The reports, so far, are making it hard to track down the exact cause since those becoming sick are spread across at least 38 states and not everyone is using the same set of products or vaping liquids in their e-cig.

So far, the FDA thinks that the fault may not lie with the design of the e-cigs or the intended chemical makeup of individual vaping liquids, but might be with a lack of consistency or care somewhere in the supply chain. “There may be a problem with source material or modification that may be occurring at different places,” a CDC official said.

Unfortunately, right now the causes are not known and may not be known for weeks or months. The fast growing vaping industry may be subject to additional regulation in the future, but for now, the safest bet is to only buy vaping supplies from a reliable source or hold off vaping all together until a root cause to these illnesses can be found.