UNITED NEWS INTERNATIONAL (UNI) — A new study published Tuesday, June 26 suggests flight attendants are at a high risk of developing cancer.

Researchers at the Harvard T.H. Chan School of Public Health collected data from nearly 5,300 flight attendants.

The data shows they have a high chance of uterine, cervical, gastrointestinal and thyroid cancers.

Female flight attendants have a 50 percent higher chance of breast cancer than the general population.

The researchers don’t provide an answer to support why flight attendants report higher cancer numbers but have some thoughts based on earlier research.

A possible reason is an exposure to potential carcinogens like cosmic ionizing radiation which is elevated at higher altitudes.

Other likely contributing factors include circadian rhythm disruption and poor cabin air quality.

Flight attendants who worked during the time when smoking on board was allowed were exposed to high levels of second-hand smoke.