For those interested read this Report/Web page from the CDC - National Institute For Occupational Safety and Health
NIOSH Website on Aircrew Exposure to Cosmic Radiation and the
FAA tool for calculation of each flight exposure
As you will see from reading the sites there is not a lot of certainty and a great degree of caution. As the Sun is now 'quiet' the solar wind is reduced and galactic radiation 'cosmic rays' entering the atmosphere are increasing. This will be the case until the Sun moves into the next Solar Cycle #25 and the solar wind increases reducing the number of cosmic rays from reaching Earth.