Privacy advocates worry about how well the information will be anonymized.

(Bloomberg) — Apple Inc.’s new ResearchKit software platform turns the iPhone into a diagnostic tool drawing medical data from millions of potential customers, creating a boon for researchers and a headache for privacy advocates.

With iPhone users’ permission, Apple (Nasdaq:AAPL) will be able to take data gleaned from its Health app and share it with doctors and scientists to use in medical research, said Chief Executive Officer Tim Cook at an Apple event Monday in San Francisco. The information could include user’s weight, blood pressure and activity levels, as well as information on diseases such as diabetes, cardiovascular disease, asthma and breast cancer.

Apple’s apps “already help millions of customers track and improve their health,” said Jeff Williams, Apple’s senior vice president of operations, in a statement. “With hundreds of millions of iPhones in use around the world, we saw an opportunity for Apple to have an even greater impact by empowering people to participate in and contribute to medical research.”

See also: To your good health: Delivering iValue.

ResearchKit joins health-tracking technology tools such as Fitbit Inc.’s wristwear that can generate reams of data on people’s health and activity levels. While researchers are enthused about having access to such information culled from a diverse population, privacy advocates are concerned the information could be tied to individual users.

As the iPhone’s technology has advanced, the data it can capture on its users’ activity has gone far beyond the basics, like the number of steps a user has taken in a day. Researchers will be able to ask for access to the accelerometer, microphone, gyroscope and GPS sensors in the iPhone “to gain insight into a patient’s gait, motor impairment, fitness, speech and memory,” Apple said in its statement.

Using separate devices made by other companies, the iPhone can also gather information such as glucose levels and asthma inhaler use.

FTC meeting

Apple executives met with at least two U.S. Federal Trade Commission staff members and Chairwoman Edith Ramirez last fall to demonstrate the Apple Watch and Health app, Bloomberg reported in January.

Among the issues discussed was how Apple’s products collect and use consumer health data, said people familiar with the matter. The company expressed a commitment to protecting consumer data and explained that under its terms of service, data collected by the watch and health apps can’t be shared with third-party data brokers, one of the people said.

Williams and three other vice presidents met with Food and Drug Administration Commissioner Margaret Hamburg and her staff about mobile medical applications in December 2013.

FDA officials told the Apple executives that they regulate based on the intended use of a device.

Diverse population

ResearchKit’s main appeal to medical researchers will be in recruiting people for large-scale studies. The system will let users complete tasks, submit surveys and fill out consent paperwork.

Typically, study subjects are recruited through local clinics or patient groups. Being able to access thousands of patients’ data from a broad geographical reach and diverse background could help speed up research.

A handful of medical institutions, including the Icahn School of Medicine at Mount Sinai and Stanford Medicine, have already developed ResearchKit apps for specific diseases, including asthma and cardiovascular health.

—With assistance from Shannon Pettypiece in New York and Tim Higgins in San Francisco.

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