Google acknowledged this week that it is collecting sensitive health data on 50 million Americans through “Project Nightingale,” a partnership with nonprofit Catholic health system Ascension. Since The Wall Street Journal broke the story, the Department of Health and Human Services’ Office for Civil Rights has opened an inquiry into the project to ensure it does not violate privacy protections.

As the Journal subsequently reported, the tech giant is gathering health records from Ascension facilities in 21 states without informing patients—nearly 50 million of them. According to CNN Business, Google said the partnership with Ascension was a “business arrangement to help a provider with the latest technology, similar to the work we do with dozens of other health care providers.” The project would allow Ascension to analyze patient data in order to find improved and innovative ways to offer care.

One of the problems is that at least 150 employees at Google had access to the data. The search giant said Ascension’s data “cannot be used for any other purpose than for providing these services we’re offering under the agreement, and patient data cannot and will not be combined with any Google consumer data.”

In other words, Google said it is following the federal rules established by the Health Insurance Portability and Accountability Act of 1996 (HIPPA), which protects individuals’ sensitive health information. The federal HHS inquiry was opened to ensure this is the case.

Ascension is based in St. Louis and operates about 2,600 facilities in about 24 states.

In a press release, the nonprofit health system stated: “All work related to Ascension’s engagement with Google is HIPAA compliant and underpinned by a robust data security and protection effort and adherence to Ascension’s strict requirements for data handling.”

“Ascension is a leader at increasing patient access to care across all regions and backgrounds, particularly those in disadvantaged communities. We’re proud to partner with them on their digital transformation,” added Tariq Shaukat, the president of Google Cloud. “By working in partnership with leading health care systems like Ascension, we hope to transform the delivery of health care through the power of the cloud, data analytics, machine learning and modern productivity tools—ultimately improving outcomes, reducing costs and saving lives.”