medhead
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This interesting thesis just crossed my desk and I thought it might be of interest to some of you. The link is to the full thesis. But I've included the abstract below for the summary.
Basically, they found an elevated overall cancer risk for cabin crew compared to the general population. But no relation was found between estimated cosmic radiation exposure and cancer risk. This is a Finnish study so the findings are for nordic cabin crew and I assume population.
http://www.stuk.fi/julkaisut_maaray...files/89297272740455112/default/stuk-a257.pdf
Abstract
Cosmic radiation dose rates are considerably higher at cruising altitudes of airplanes than at ground level. Previous studies have found increased risk of certain cancers among aircraft cabin crew, but the results are not consistentacross different studies. Despite individual cosmic radiation exposure assessmentis important for evaluating the relation between cosmic radiation exposureand cancer risk, only few previous studies have tried to develop an exposureassessment method. The evidence for adverse health effects in aircrews due to ionizing radiation is inconclusive because quantitative dose estimates have not been used. No information on possible confounders has been collected. For an occupational group with an increased risk of certain cancers it is very important to assess if the risk is related to occupational exposure.
The goal of this thesis was to develop two separate retrospective exposure assessment methods for occupational exposure to cosmic radiation. The methods included the assessment based on survey on flight histories and based on company flight timetables. Another goal was to describe the cancer incidence among aircraft cabin crew with a large cohort in four Nordic countries, i.e., Finland, Iceland, Norway, and Sweden. Also the contribution of occupational as well as non-occupational factors to breast and skin cancer risk among the cabin crew was studied with case-control studies.
Using the survey method of cosmic radiation exposure assessment, the median annual radiation dose of Finnish airline cabin crew was 0.6 milliSievert (mSv) in the 1960s, 3.3 mSv in the 1970s, and 3.6 mSv in the 1980s. With the flight timetable method, the annual radiation dose increased with time being 0.7 mSv in the 1960 and 2.1 mSv in the 1995. With the survey method, the median career dose was 27.9 mSv and with the timetable method 20.8 mSv. These methods provide improved means for individual cosmic radiation exposure assessment compared to studies where cruder indicators, such as number of work years for occupational exposure, were used. When selecting the approach for further studies, the feasibility issues of the study affect the decision, i.e., can the flight history data of the cabin crew be collected by a survey or are the historical flight timetables available from the flight company.
In the follow-up of more than 10,000 Nordic cabin crew members, the standardized incidence ratio (SIR) of all cancers was 1.16 (95% confidence interval (CI): 1.06 – 1.25) for women and 1.39 (95% CI: 1.17 – 1.62) for men. These results confirm the evidence for an elevated overall cancer risk among cabin crew compared to the general population. Of specific cancer types, the significant risks were observed for breast cancer, cutaneous malignant melanoma, non-melanoma skin cancer, leukaemia, Kaposi sarcoma, laryngeal and pharyngeal cancer.
This thesis cannot not provide an explanation for the elevated breast or skin cancer risk among aircraft cabin crew. Breast cancer is previously known to be strongly related to reproductive and hormonal factors – including endogenous hormone levels and exogenous hormone use. Thus, these factors may present the plausible explanation for the increased risk of breast cancer also among cabin crew. Exposure to ultraviolet radiation (UVR) is the most likely explanation for the increased risk of skin cancers, but there was no evidence on cabin crew excess exposure to UVR compared to general population in this work.
Finding a cause for the increased incidence of cancer among cabin crew warrants further studies. This work found no relation between estimated occupational cosmic radiation exposure and cancer risk. The current exposure limitations of radiation to cabin crew need not be altered.
Basically, they found an elevated overall cancer risk for cabin crew compared to the general population. But no relation was found between estimated cosmic radiation exposure and cancer risk. This is a Finnish study so the findings are for nordic cabin crew and I assume population.
http://www.stuk.fi/julkaisut_maaray...files/89297272740455112/default/stuk-a257.pdf
Abstract
Cosmic radiation dose rates are considerably higher at cruising altitudes of airplanes than at ground level. Previous studies have found increased risk of certain cancers among aircraft cabin crew, but the results are not consistentacross different studies. Despite individual cosmic radiation exposure assessmentis important for evaluating the relation between cosmic radiation exposureand cancer risk, only few previous studies have tried to develop an exposureassessment method. The evidence for adverse health effects in aircrews due to ionizing radiation is inconclusive because quantitative dose estimates have not been used. No information on possible confounders has been collected. For an occupational group with an increased risk of certain cancers it is very important to assess if the risk is related to occupational exposure.
The goal of this thesis was to develop two separate retrospective exposure assessment methods for occupational exposure to cosmic radiation. The methods included the assessment based on survey on flight histories and based on company flight timetables. Another goal was to describe the cancer incidence among aircraft cabin crew with a large cohort in four Nordic countries, i.e., Finland, Iceland, Norway, and Sweden. Also the contribution of occupational as well as non-occupational factors to breast and skin cancer risk among the cabin crew was studied with case-control studies.
Using the survey method of cosmic radiation exposure assessment, the median annual radiation dose of Finnish airline cabin crew was 0.6 milliSievert (mSv) in the 1960s, 3.3 mSv in the 1970s, and 3.6 mSv in the 1980s. With the flight timetable method, the annual radiation dose increased with time being 0.7 mSv in the 1960 and 2.1 mSv in the 1995. With the survey method, the median career dose was 27.9 mSv and with the timetable method 20.8 mSv. These methods provide improved means for individual cosmic radiation exposure assessment compared to studies where cruder indicators, such as number of work years for occupational exposure, were used. When selecting the approach for further studies, the feasibility issues of the study affect the decision, i.e., can the flight history data of the cabin crew be collected by a survey or are the historical flight timetables available from the flight company.
In the follow-up of more than 10,000 Nordic cabin crew members, the standardized incidence ratio (SIR) of all cancers was 1.16 (95% confidence interval (CI): 1.06 – 1.25) for women and 1.39 (95% CI: 1.17 – 1.62) for men. These results confirm the evidence for an elevated overall cancer risk among cabin crew compared to the general population. Of specific cancer types, the significant risks were observed for breast cancer, cutaneous malignant melanoma, non-melanoma skin cancer, leukaemia, Kaposi sarcoma, laryngeal and pharyngeal cancer.
This thesis cannot not provide an explanation for the elevated breast or skin cancer risk among aircraft cabin crew. Breast cancer is previously known to be strongly related to reproductive and hormonal factors – including endogenous hormone levels and exogenous hormone use. Thus, these factors may present the plausible explanation for the increased risk of breast cancer also among cabin crew. Exposure to ultraviolet radiation (UVR) is the most likely explanation for the increased risk of skin cancers, but there was no evidence on cabin crew excess exposure to UVR compared to general population in this work.
Finding a cause for the increased incidence of cancer among cabin crew warrants further studies. This work found no relation between estimated occupational cosmic radiation exposure and cancer risk. The current exposure limitations of radiation to cabin crew need not be altered.
