Digital health companies are funneling sensitive data that patients have shared with them to Facebook to help target advertisements, according to a new study from research group the Light Collective. In some cases this sharing is running afoul of the companies own privacy policies and raising concerns about HIPAA violations.The peer-reviewed study, published Monday in Patterns, a data science journal, examines the way data from individuals health-related activity online is tracked across websites or platforms and then used for advertising purposes on Facebook. The researchers studied the online activities of 10 participants active in the online cancer community who had used digital health tools from five different companies: Color Genomics, Myriad Genetics, Invitae, Health Union and Ciitizen. They found that third-party ad trackers used by those companies followed the patients online and marketed to them based on those activities. Three of the companies went against their own privacy policies in the process.