People of color who depend on their wearable devices to monitor their heart rates might be getting inaccurate readings, a report suggests.

According to STAT, nearly all of the popular smartwatches and fitness trackers currently in the market use a technology that becomes less reliable when used by people who have darker skin tones.

The report stated that Fitbit, one of the top wearable tech companies in the world, uses the potentially problematic technology in all of its heart rate trackers. The technology is also found in many of the devices sold by Garmin and Samsung.

The report revealed that the Apple Watch also uses the technology, but the device employs another method to track heart rate to give the wearer a more accurate reading.

The Problem Is Green Light

To monitor a wearer's heart rate, a wearable device typically uses optical sensors that are capable of monitoring the volume of blood. In between heartbeats, when there is less blood at the wrist, more light is being reflected back to the sensor. This allows the device to monitor the user's heart rate.

The problem, however, is some companies like Fitbit and Samsung use green light. The green light is cheaper, but it also has a shorter wavelength easily absorbed by melanin.

The darker the skin tone of the wearer is, the more difficult it would be to get an accurate heart rate reading from a device that uses green light.

Several consumers complained that heart rate monitoring does not work on their dark skin. STAT noted that a paper published in 2017 investigated the link between race and the accuracy of heart rate trackers made similar alarming findings.

The use of the potentially problematic technology present serious implications for users and scientific research that uses these popular devices to monitor the health of participants.

"It really is about the existing bias in medicine that we have already," said Kadija Ferryman, a cultural anthropologist, to STAT. "No matter what [the] technology is, there is evidence that ... inserting another tool, no matter how advanced it is, will likely continue on and continue to uphold the existing biases or exacerbate them."

Fitbit Issues Statement

Fitbit, in a statement to KPIX5, stood by their fitness trackers, saying that the technology has been through rigorous testing to ensure accuracy.

"To achieve the most consistent performance, we specifically designed our optical system to emit green light at sufficient strength to effectively penetrate darker skin and our detector to be sensitive enough to accurately detect the heart rate signal," the company explained.