The potential cancer risks for flight attendants are not limited to cosmic ionizing radiation. Cabin crew members are also regularly exposed to more UV radiation than the general population, which can make these workers more vulnerable to skin cancers, Mordukhovich said. In addition, some studies have found that circadian rhythm disruptions, such as jet lag, might be linked with an increased risk of cancer, she said. These disruptions could lead to changes in immune function and cell metabolism, which can reduce the suppression of tumors. Another possible threat to the health of cabin crew members is chemical exposure, according to the study. The women and men who worked as flight attendants prior to 1988, when smoking was first banned on some U.S. flights, were routinely exposed to secondhand smoke while on board the aircraft. Other chemical contaminants found in the cabin may include engine leakages, pesticides and flame retardants, which contain compounds that may act as hormone disruptors and increase the risk of some cancers, Mordukhovich said. Further complicating matters is that flight attendants in the U.S. don't have the same occupational protections as their counterparts in the European Union. There, exposure levels to radiation as well as work schedules are routinely monitored and adjusted to make sure flight attendants don't exceed certain guidelines for carcinogen exposure, Mordukhovich said. There has been only limited research on the health of flight attendants, but they may not be the only air travelers to experience higher rates of cancer. The rates may also be higher for pilots and people who fly often as passengers, Mordukhovich said. Studies of pilots have generally shown higher rates of skin and prostate cancers, she noted, adding that pilots also have been found to have circadian rhythm disruption, but these workers have somewhat more built-in protections around their scheduling and rest times than flight attendants do. Although the cancer risks for frequent flyers have not yet been studied, there is no reason to suspect these people would not have similar risks as those faced by cabin crews, Mordukhovich said. Some limitations of the study are that researchers were not able to take into consideration individual UV exposures, such as sunbathing habits or leisure-time activities, which could influence skin cancer risk. In addition, cancer rates were self-reported by study participants, and these diagnoses were not confirmed by a check of their medical records by the researchers, according to the study. The study was published online today (June 25) in the journal Environmental Health.