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Niren L Nagda and Michael D Koontz - REVIEW OF STUDIES ON FLIGHT ATTENDANT HEALTH AND COMFORT IN AIRLINER CABINS – Aviation, Space, and Environment Medicine, Vol. 74, No. 2 February 2003

Background:
A number of studies have examined the effect of the airliner cabin environment and other factors on the health and comfort of flight attendants (FAs), but no comprehensive review of such studies is available.

Methods:
This paper reviews studies conducted after 1980 that addressed FA short-term health and comfort effects. Relevant literature was identified using the National Institute of Health’s PUBMED database.

Results:
Twenty-one studies were identified and classified into two types: in-flight surveys and surveys of general flight experiences. Most studies used questionnaires to obtain perceptions of the cabin environment, comfort, and health-related symptoms, but some included objective measurements. Only a few studies used a random sample or control groups. Effects of confounding variables generally have not been analyzed.

Discussion:
Most studies shared some weaknesses such as poor response rate, significant response bias, exclusive reliance on questionnaires, or limited analysis. Taken together, the studies indicate that various complaints and symptoms reported by FAs to be associated with their job duties and with the cabin environment. Most notable are “dryness” symptoms attributable to low humidity and “fatigue” symptoms associated with factors such as disruption of circadian rhythm. Practically all symptoms are exacerbated by longer flight durations. Studies citing problems of “poor aircraft cabin air quality” tend to be weak in design and have addressed only general flight experiences of FAs. Although certain FA complaints are consistent with possible exposure to air pollutants, the relationship has not been proven and such complaints also are consistent with causes other than poor air quality.

S.K. Kakkos and G Geroulakos – REVIEW – ECONOMY CLASS STROKE SYNDROME: CASE REPORT AND REVIEW OF THE LITERATURE – Eur J Vasc Endovasc Surg 273, 239-243 (2004)

Objectives.
Venous thromboembolism associated with travelling, or economy class syndrome, is increasingly recognized as a sequence of long haul flights and so paradoxical cerebral embolism through a patent foramen ovale.

Materials and methods.
We present a new case of economy class stroke syndrome and review of the literature using MEDLINE search.

Results:
Literature review identified 12 additional cases. In most of them, stroke occurred in close approximation with landing of the aircraft following a long-haul flight. Venous thromboembolism was present in 58%, while a patent foramen ovale was diagnosed with contrast echocardiography in all but one case. Our case presented with severe left hemispheric stroke, and significant delay, two days after a long-haul flight.

Conclusions:
The small number of reported cases indicates either the rarity of this entity or unawareness of its existence. The true incidence of this condition remains unknown. However, because of treatment implications such as the need to treat venous thromboembolism or close the patent foramen ovale, clinicians should be aware of this entity.


CABIN AIR QUALITY

Cynthia R Driver, RN, MPH; Sarah E. Valway, DMD, MPH; W. Meade Morgan, PhD; Ida M. Onorato, MD; Kenneth G. Castro, MD – TRANSMISSION OF MYCOBACTERIUM TUBERCULOSIS ASSOCIATED WITH AIR TRAVEL, JAMA, October 5, 1994 – Vol 272, No.13

Objective: To investigate potential transmission of Mycobacterium tuberculosis in aircraft from a crew member with tuberculosis. Design: Retrospective cohort study and survey. Setting: A large US airline carrier. Participants: A total of 212 crew members and 59 passengers who were exposed to a crew member with tuberculosis during a potentially infectious period (May through October 1992). Comparison volunteer sample of 247 unexposed crew members. Main Outcome Measures: Positive tuberculin skin test (TST) result or tuberculosis. Results: Rates of positive TST results were higher among foreign-born persons in all study groups. Among US-born comparisons and contacts, rates of positive TST results did not differ between comparisons and contacts exposed from May though July (5.3% vs 5.9%, respectively). However, contacts exposed from August through October had significantly higher rates of positive TST results than did contacts exposed from May through July (30% vs 5.8%, respectively; P<.001); two had documented TST conversions between September 1992 and February 1993. The risk of infection increased with increasing hours of exposure to the index case. Four (6.7%) of 59 frequent flyers were TST-positive; all flew in October. Conclusions: Data support the conclusion that M tuberculosis was transmitted from an infectious crew member to the other crew member son an aircraft. Because of the clustering of TST-positive frequent flyers in October then the index patient was most infectious, transmission of M tuberculosis to passengers cannot be excluded.

Thomas A Kenyon, M.D., M.P.H., Sarah E. Valway, D.M.D., M.P.H., Walter W. Ihle, M.P.A., Ida M. Onorato, MD., and Kenneth G. Castro, M.D. – TRANSMISSION OF MULTIDRUG-RESISTANT MYCOBACTERIUM TUBERCULOSIS DURING A LONG AIRPLANE FLIGHT – The New England Journal of Medicine, Volume 334, April 11, 1996, Number 15

Abstract:
Background. In April 1994, a passenger with infectious multidrug-resistant tuberculosis travelled on commercial-airline flights from Honolulu to Chicago and from Chicago to Baltimore and returned one month later. We sought to determine whether she had infected any of her contacts on this extensive trip.

Methods:
Passengers and crew were identified from airline records and were notified of their exposure, asked to complete a questionnaire, and screened by tuberculin skin tests.

Results:
Of the 925 people on the airplane, 802 (86.7 percent) responded. All 11 contacts with positive tuberculin skin tests who were on the April flights and 2 of 3 contacts with positive tests who were on the Baltimore-to-Chicago flight in May had other risk factors for tuberculosis. More contacts on the final, 8.75-hour flight from Chicago to Honolulu had positive skin tests than those on the other three flights (6 percent, as compared with 2.3, 3.8, and 2.8 percent). Of 15 contacts with positive tests on the May flight from Chicago to Honolulu, 6 (4 with skin-test conversions) had no other risk factors; all 6 had sat in the same section of the plane as the index patient (P = 0.001). Passengers seated within two rows of the index patient were more likely to have positive tuberculin skin tests than those in the rest of the section (4 of 13, or 30.8 percent, vs. 2 of 55, or 3.6 percent; rate ratio, 8.5; 95 percent confidence interval, 1.7 to 41.3; P 0.01).

Conclusions:
The transmission of Mycobacterium tuberculosis that we describe aboard a commercial aircraft involved a highly infectious passenger, a long flight, and close proximity of contacts to the index patient. (N Engl J Med 1995; 334:933-8).


GL Nichols, M Rutter, R Rooney (PHLS) Environmental Surveillance Unit), N Andrews (PHLS Statistics Unit), M Young (Association of Port Health Authorities) – MICROBIOLOGICAL QUALITY OF POTABLE WATER SUPPLIED TO AND STORED ON COMMERCIAL AIRCRAFT – Conference Paper 101 Annual Meeting, Association of Port Health Authorities, 20.6.2000

Introduction
Water is supplied to aircraft through a supply chain where it is vulnerable to microbiological contamination. The water is generally transported from mains supplies to the aircraft via bowsers (water tank vehicles). Water is stored on most commercial aircraft in a water tank that is filled by pumping water through a filling point on the outside of the aircraft until the tank is full and water passes from the tank overflow. There are currently no specific regulations or guidelines governing the microbiological quality of drinking water on aircraft, although the water supply is expected to comply with UK drinking water regulations. Many of the hygiene issues relate to the bowsers and hoses used to supply the aircraft and to the aircraft themselves. The bowsers may be poorly maintained and bad practices may be used in filling. The water supply points may also be poorly maintained. In addition, for aircraft undertaking international flights, drinking water may be uplifted in countries where the water regulations and hygiene are less stringent than in the UK and EU.

The study was carried out for a 6-month period at each of thirteen major airports in the UK and Isle of Man between July 1998 and March 1999 in order to compare the microbiological quality of potable water at different points in the supply chain. A total of 850 water samples were obtained from airport mains supply points, from bowsers during transport to the aircraft and from water taps aboard the aircraft.

Hygiene practices associated with the water supply chain within airports and on board aircraft were examined by requesting airports, airlines and bowser companies involved to complete a questionnaire.

Compliance of Samples with UK Mains Water Regulations
Current UK water regulations state that the bacterial indicators faecal coliforms (E. coli) should be absent from 100mL samples of water and total coliforms should be absent from 100mL samples of water in 95% or more of samples. In this study samples were considered to have failed if there was any E.coli, coliforms or faecal streptococci in the water. Table 1 shows the numbers and percentages of samples form each sampling point positive for microbiological parameters. Overall, it shows that 8.7% of samples failed. The highest percentage of samples failing were taken from the aircraft drinking water fountain (15.8%), followed by bowers (10.2%), aircraft galley tap (7.9%) and then mains supply points (6.8%).

Water quality varied greatly between airports. Just over a third of the total of all samples failing were taken at one airport, while over half were from a combination of two airports.

E. Coli
Few samples (3/845) were positive for E. coli (Table 1). However, in the 2 positive samples taken from bowsers, the E. coli counts were high (264 and >20 organisms per 100mL, respectively).


Torsten Lindgren, B.S., Dan Norbäck, Ph.D., Kjell Andersson, M.D., and Bo-Goran Dammstrom, M.D. – CABIN ENVIRONMENT AND PERCEPTION OF CABIN AIR QUALITY AMONG COMMERCIAL AIRCREW – Aviation, Space and Environmental Medicine, Vol 71, No. 8 August 2000

Objective:
Our objective was to study the perception of cabin air quality (CAQ) and cabin environment (CE) among commercial cabin crew, and to measure different aspects of CAQ on intercontinental flights.

Methods:
A standardized questionnaire was mailed in February-March 1997 to all Stockholm-based aircrew on duty in a Scandinavian flight company (n = 1857), and office workers from the same company (n = 218). The answers were compared with an external reference group for the questionnaire (MM 040 NA). During this time, smoking was allowed on intercontinental flights, but not on other shorter flights. Smoking was prohibited on all fights after 1 September 1997. The participation rate was 81% (n = 1513) in the aircrew, and 77% (n = 168) in the office group. Air humidity, temperature, carbon dioxide (CO2) and respirable dust were measured during intercontinental flights, during both smoking and non-smoking conditions. Statistical analysis was performed by multiple logistic regression analysis, keeping age, gender, smoking, current smoking, occupation and perceived psychosocial work environment simultaneously in the model.

Results:
Air humidity was very low (mean 5%) during intercontinental flights. In most cases (97%) the CO2 concentration was below 1000 ppm. The average concentration of respirable particles was 67 µg . m-3 during smoking conditions, and 4 µg . m-3 during non-smoking conditions. Complaints of draftiness, too high temperature, varying temperature, stuffy air, dry air, static electricity, noise, inadequate illumination, and dust were more common among aircrew as compared with office workers from the same company. Female crew had more complaints on too low temperature, dry air, and dust. Current smokers had less complaints on stuffy air and environmental tobacco smoke (ETS). Younger subjects and those with atopy (childhood eczema, allergy to tree or grass pollen, or furry animals) reported more complaints. Reports on work stress and lack of influence on working conditions were strongly related to perception of a poor cabin environment. Flight deck crew had more complaints about inadequate illumination and dust, but less complaints about other aspects of the cabin environment, as compared with flight attendants. Aircrew who had been on a flight the previous week, where smoking was allowed, had more complaints on dry air and ETS.

Conclusion:
Complaints about work environment seems to be more common among aircrew than office workers, particularly draft, stuffy air, dry air, static electricity, noise, inadequate illumination and dust,. We could identify personal factors of importance, and certain conditions that could be improved, to achieve a better perception of the cabin environment. Important factors were work stress, lack of influence on the working conditions, and environmental tobacco smoke on some longer flights. The hygienic measurements in the cabin, performed only on intercontinental smoking flights, showed that air humidity is very low onboard, and tobacco-smoking onboard leads to significant pollution from respirable dust.


US NATIONAL RESEARCH COUNCIL – THE AIRLINER CABIN ENVIRONMENT AND THE HEALTH OF PASSENGERS & CREW, National Academic Press 2002.

Characteristics Potential Health Impacts Frequency of Exposure Availability of Information
High Concern
Cabin pressure Serious in infants and those with cardiorespiratory disease Nearly all flights Reliable measurements available; effects on sensitive groups uncertain
Ozone (O3) Airway irritation and reduced lung function Higher concentrations in aircraft w/o O3 converters Few systematic measurements
Moderate Concern
Airborne allergens Eye, nose, sinus irritation, acute asthma attacks Frequency unknown Little exposure data; only self-reports from hypersensitive persons
Carbon monoxide (CO2) Headaches, lightheadedness Frequency uncertain, believed to be low Reliable data for normal operating conditions; no data for incidents
Hydraulic fluids or engine oils (constituents or degradation products) Mild to severe neurological effects Frequency uncertain, believed to be low No exposure data available. Little information on health effects of smoke, mists, odors in cabin.
Infectious agents Exposure may have no effect or cause infection w/o symptoms Presence of infectious agents likely; frequency of exposure and resulting infections unknown Little information on transmission of infectious agents on aircraft
Pesticides Skin rashes Exposure likely on certain international flights No exposure data available; only self-reported on health effects
Low Concern
Carbon dioxide (CO2) Elevated concentrations associated with perception of poor air quality Concentrations generally below FAA limits Reliable measurements available only for normal operating conditions
Deicing fluids Health effects from inhaling high concentrations Frequency expected to be low No information available on incidents of fluids entering aircraft
Nuisance odors Annoyance and mucosal irritation Can be present on any flight Reliable information from surveys of cabin occupants
Relative humidity Drying of skin, eyes, mucous membranes Low humidity (10%-20%) occurs on most flights Reliable measurements available

Martin B Hocking – TRENDS IN CABIN AIR QUALITY OF COMMERCIAL AIRCRAFT: INDUSTRY AND PASSENGER PERSPECTIVES, Review on Environmental Health - Volume 17, No 1, 2002

Abstract:
The small air space available per person in a fully occupied aircraft passenger cabin accentuates the human bioeffluent factor in the maintenance of air quality. The accumulation of carbon dioxide and other contributions to poor air quality that can occur with inadequate ventilation, even under normal circumstances, is related to the volume of available air space per person and various ventilation rates. This information is compared with established air quality guidelines to make specific recommendations with reference to aircraft passenger cabins under both normal and abnormal operating conditions.

The effects of respiration on the air quality of any enclosed space from the respiration of a resting adult are estimated using standard equations. Results are given for different volumes of space per person, for zero air exchange, and for various air change rates. The required ventilation rates estimated in this way compared closely with results calculated using a standard empirical formula. The results confirm that the outside air ventilation required to achieve a target carbon dioxide concentration in the air of an occupied enclosed space remains the same regardless of the volume of that space.

The outside air ventilation capability of older and more recent aircraft is then reviewed and compared with the actual measurements of cabin air quality for these periods. The correlation between calculated and measured aircraft cabin carbon dioxide concentration from other studies was very good. Respiratory benefits and costs of returning to the 30% higher outside air ventilation rates and 8% higher cabin pressures of the 1960s and 1970s are outlined. Consideration is given to the occasional occurrence of certain types of aircraft malfunction that can introduce more serious contaminants to the aircraft cabin.

Recommendations and suggestion for aircraft builders and operators are made that will help improve aircraft cabin air quality and the partial pressure of oxygen that is available to passengers at minimal cost. Also suggested are some measures that passengers can take to help improve their comfort and decrease their risk of illness, particularly on long-haul flights.


JETLAG

Charles M. Winget, B.A., PH.D., Charles W. DeRoshia, B.S., M.A., Carol L. Markley, B.A., M.A., and Daniel C Holley, M.S., PH.D. – A REVIEW OF HUMAN PHYSIOLOGICAL AND PERFORMANCE CHANGES ASSOCIATED WITH DESYNCHRONOSIS OF BIOLOGICAL RHYTHMS, Science and Technology Committee: 1984-Selected Review Paper, Vol. 55, Number 12, December 1984, Aviation, Space and Environmental Medicine.

This review discusses the effects, in the aerospace environment, of alterations in approximately 24-h periodicities (circadian rhythms) upon physiological and psychological functions and possible therapies for desynchronosis induced by such alterations. The consequences of circadian rhythm alteration resulting from shift work, transmeridian flight, or altered day lengths are known as desynchronosis, dysrhythmia, dyschrony, jet lag, or jet syndrome. Considerable attention is focused on the ability to operate jet aircraft and manned space vehicles. The importance of environmental cues, such as light-dark cycles, which influence physiological and psychological rhythms is discussed. A section on mathematical models is presented to enable selection and verification of appropriate preventive and corrective measures and to better understand the problem of dysrhythmia.

Philippa H. Gander, Ph.D., De Nguyen, B.E., Mark R. Rosekind, Ph.D., and Linda J Connell, M.A. – AGE, CIRCADIAN RHYTHMS, AND SLEEP LOSS IN FLIGHT CREWS, Aviation, Space & Environmental Medicine, Volume 64, Number 3, Section 1, March 1993

Age-related changes in trip-induced sleep loss, personality (n = 205), and the pre-duty temperature rhythm (n = 91) were analyzed in crews from various flight operations. Eveningness decreased with age (subjects aged 20-30 were more evening-type than subjects over 40.) The minimum of the baseline temperature rhythm occurred earlier with age (earlier in subjects aged 30-50 than in subjects aged 20-30). The amplitude of the base-line temperature rhythm declined with age (greater in subjects aged 20-30 than in subjects over 40). Average daily percentage sleep loss during trips increased with age.

Among crewmembers flying long-haul flight operations, subjects aged 50-60 averaged 3.5 times more sleep loss per day than subjects aged 20-30. These studies support previous findings that evening types and subjects with late peaking temperature rhythms adapt better to shift work and time zone changes. Age and circadian type may be important considerations for duty schedules and fatigue countermeasures.


IN-FLIGHT MEDICAL INCIDENTS

AMA Commission on Emergency Medical Services – MEDICAL ASPECTS OF TRANSPORTATION ABOARD COMMERCIAL AIRCRAFT – Air Transportation – Commission on Emergency Medical Services – JAMA, Feb 19, 1982 – Vol 247. No 7

Air transportation is relatively safe: the death rate during flight for the period 1976 to 1979 was one per 6.4 million revenue passengers, with approximately one flight diversion for medical reasons per 10,000 scheduled flights. However, the incidence of nonfatal medical emergencies is unknown. Transport by air of patients who are not critically ill is expeditious, safe, comfortable, and convenient.

Airline travel presents two major problems to the medical profession: (1) What advice should be given to a patient who wishes to travel by air? (2) How should the physician respond to emergencies that arise during a flight on which the physician himself is a passenger, and how are common in-flight emergencies handled?

This is a brief review of the principles of high-altitude flight, the potential effects on medical and surgical conditions, and recommendations for care of problems that occur in-flight.


Charles A DeJohn, Alex M Wolbrink, Stephen J H Véronneau, Julie G Larcher, David W Smith, and Joan S Garrett – AN EVALUATION OF IN-FLIGHT MEDICAL CARE IN THE US – Aviation, Space and Environmental Medicine, Vol. 73, No. 6, June 2002

Background:
In-flight medical care has been studied for many years. In an effort to evaluate in-flight medical care delivery on U.S. airlines, this study includes a detailed correlation between in-flight medical care, patient response, and post-flight follow up.

Methods:
A survey of five U.S. domestic air carriers from October 1, 1996 to September 30, 1997 showed 1132 in-flight medical incidents. These airlines accounted for approximately 22% of scheduled U.S. domestic enplanements during the period.

Results:
Results indicate that there was good overall agreement between in-flight and post-flight diagnoses (79% of cases), and passenger condition improved in a majority of cases (60%).

Conclusions:
The results suggest that in-flight diagnoses were generally accurate and treatment appropriate.


Eugene F Delaune III, Raymond H Lucas and Petra Illig – IN-FLIGHT MEDICAL EVENTS AND AIRCRAFT DIVERSIONS: ONE AIRLINE’S EXPERIENCE – Aviation, Space, and Environmental Medicine, Vol. 74, No. 1 January 2003

Background:
An aging population combined with the increasing mobility of people with acute and chronic illnesses could make an increase in the frequency of in-flight medical events aboard commercial aircraft likely.

Objectives:
To determine the incidence of each type of in-flight medical complaint, the appropriateness of medical kit contents, which factors lead to aircraft diversion, and which factors effect the appropriateness of the decision to divert.

Methods:
Medical complaints reported aboard a sample airline from July 1, 1999 through June 30, 2000 were studied. The frequency of aircraft diversion was related to compliant and medical assistance provided. The appropriateness of the decision to divert was determined as a function of hospital admission rates.

Results:
There was an incidence of 22.6 medical complaints per million passengers and 0.1 deaths per million passengers. There were 210 diversions per million flights with one of ever 12.6 incidents resulting in a diversion. When a passenger volunteer was used, they opened the medical kit 62% of the time. When a physician participated in the decision to divert, the hospital admission rate was 49% versus 15% with no physician input.

Conclusion:
Variations in incidence of medical complaints cited in previous studies demonstrate the need for an industry-wide standardized reporting method of in-flight medical events. All in-flight medical complaints could likely have been adequately treated with the contents of the FAA’s newly mandated medical kits. Physician participation in decisions to divert aircraft should be sought as it is associated with more appropriate divert decisions.


Russell B Rayman, David Zanick, and Trina Korsgard – RESOURCES FOR INFLIGHT MEDICAL CARE – Aviation, Space and Environmental Medicine, Vol 75, No. 3, March 2004 278-80.

With the anticipated growth of air travel, in-flight illness and injury are expected to increase as well. This is because more elderly people and people with preexisting disease are taking to the air. Although in-flight medical events and deaths are uncommon, physician passengers are occasionally called upon to render care.

Resources for the physician may include emergency medical kits, automatic external defibrillators (AEDs), ECG monitors, portable oxygen bottles, and first-aid kits. Most airlines provide around-the-clock air-to-ground radio consultation either with their own medical department personnel or contracted medical consultants. Furthermore, some flight attendants are trained in cardio-pulmonary resuscitation, first-aid, and operation of AEDs. This paper describes those in-flight resources available to a physician who is called upon to treat an ill or injured passenger.

In a broader sense, it is also providing advice to physicians who administer in-flight medical care. The Aviation Medical Assistance Act of 1998 (“Good Samaritan act”) is also discussed.


COSMIC RADIATION AND CANCER

W Friedberg, Ph.D., D.N. Faulkner, M.S., L Snyder, E.B. Darden, Jr., Ph.D., and K O’Brien – GALACTIC COSMIC RADIATION EXPOSURE AND ASSOCIATED HEALTH RISKS FOR AIR CARRIER CREWMEMBERS – Aviation, Space and Environmental Medicine, November 1989

The dose equivalent to air carrier crewmembers from galactic cosmic radiation was estimated for each of 32 nonstop flights on a variety of routes to and form, or within, the contiguous United States. Flying times were form 0.4 to 13 hours. The annual dose equivalents received on the flights ranged from 0.2 to 9.1 mSv (20 to 910 mrem), or 0.4 to 18% of the recommended annual limit for occupational exposure of an adult.

We reviewed some of the characteristics of galactic and solar cosmic radiation and provided example calculations for estimating radiation-induced risks of fatal cancer, genetic defects and harm to an embryo or fetus. The estimated increased risk of dying from cancer because of galactic radiation exposure received during 20 years of flying ranged from 0.1 to 5 in 1,000. For the adult U.S. population the risk of dying from cancer is about 220 in 1,000.


Pierre R Band, M.D., John J Spinnelli, M.S.c., Vincent T.Y. NG, M. Math., Joanne Moody, R.N., and Richard P. Gallagher, M.Sc. – MORTALITY AND CANCER INCIDENCE IN A COHORT OF COMMERCIAL AIRLINE PILOTS – Aviation, Space and Environmental Medicine, April 1990

We undertook a cohort study of all male pilots employed since January 1, 1950, by CP Air, now Canadian Airlines International. A total of 913 eligible pilots – 630 active and 283 no longer employed – contributing 18,060 person-years of observation, were identified through company records.

As of October 31, 1988, current status was obtained on 891 (97.6%). Standardized mortality ratio (SMR) and standardized incidence ratio (SIR) were used to compare, respectively, the mortality and cancer incidence of the cohort with that of the British Columbia population. Statistical significance of the SMR and SIR by comparison with the Poisson distribution (p < 0.05 one-sided) and 90% confidence intervals (Cl) were calculated.

Excess deaths were observed for aircraft accidents (No. = 23; SMR = 21.29; P < 0.001; Cl 14.60, 30.20), brain cancer (No. = 4; SMR = 4.17, P = 0.017; Cl 1.40, 9.50) and rectal cancer (No. 3; SMR = 4.35; P – 0.033; Cl 1.20, 11.20). Excess cancer incidence was noted for non-melanoma skin cancer (No. = 26; SIR = 1.59; P = 0.017; Cl 1.10, 2.20), brain cancer (No. = 4; SIR = 3.45; P – 0.030; Cl 1.20, 7.90) and Hodgkin’s Disease (No. = 3; SIR = 4.54; P = 0.030’ Cl 1.20, 11.70). These findings, suggesting an excess risk for certain cancers in commercial airline pilots, are based on small numbers and need to be confirmed in larger cohort studies.


David Irvine, M.Sc., B.Sc., and D. Michael Davies, M.D., Ph.D. – THE MORTALITY OF BRITISH AIRWAYS PILOTS, 1966-1989: A PROPORTIONAL MORTALITY STUDY – Aviation, Space and Environmental Medicine, April 1992

Of 446 deaths among serving and retired British Airways pilots between 1996 and 1989, 411 were analyzed using the Proportional Mortality Ratio (PMR) technique. After removal of the predictable excess of aircraft accidents, excesses of cancer (PMR 1.31) and other accidents (1.60) were balanced by deficits in diseases of the circulatory (0.83) and respiratory (0.49) systems.

While lung cancer was close to expectation (1.10), consistent excesses were shown in all analyses for malignant melanoma (6.68), cirrhosis of the liver (2.88), colon cancer (2.30) and brain/CNS cancer (2.68). Consideration of these ratios in relation to pilots’ lifestyle and occupation leads to the conclusion that the brain/CNS cancer excess must be studied further.


Eero Pukkala, Anssi Auvinen, Gunilla Wahlerg – INCIDENCE OF CANCER AMONG FINNISH AIRLINE CABIN ATTENDANTS, 1967-92, BMJ, Vol 311, 1995

Objective:
To assess whether occupational exposure among commercial airline cabin attendants are associated with risk of cancer.

Design:
Record linkage study.

Setting:
Finland.

Subjects:
1577 female and 187 male cabin attendants who had worked for the Finnish airline companies.

Main outcome measure:
Standardized incidence ratio; expected number of cases based on national cancer incidences.

Results:
A significant excess of breast cancer (standardized incidence ration 1.87 (95% confidence interval 1.15 to 2.23)) and bone cancer (15.10 (1.82 to 54.40)) was found among female workers. The risk of breast cancer was most prominent 15 years after recruitment. Risk of leukaemia (3.57 (0.43 to 12.9)) and skin melanoma (2.11 (0.43 to 6.15) were not significantly raised. Among men, one lymphoma and one Kaposi’s sarcoma were found (expected number of cases 1.6).

Conclusions:
Although the lifestyle of cabin attendants is different from that of one reference population – for example, in terms of social status and parity – concentration of the excess risks to primary sites sensitive to radiation suggests that ionizing radiation during flights may add to the cancer risk of all flight personnel. Otherwise the lifestyle of cabin attendants did not seem to affect their risk of cancer. Estimates of the effect of reproductive risk factors only partly explained the increased risk of breast cancer. If present estimates of health hazards due to radiation are also valid for cosmic radiation, the radiation doses of cabin attendants seem too small to account entirely for the observed excess risk.


Maria Blettner, Hajo Zeeb, Ingo Langner, Gaël P. Hammer, and Thomas Schafft from the Department of Epidemiology and Medical Statistics, School of Public Health –
Pierre R Band, Nhu D. Le, Raymond Fang, Michele Deschamps, Andrew J Coldman, Richard P Gallagher, and Joanne Moody – COHORT STUDY OF AIR CANADA PILOTS: MORTALITY, CANCER INCIDENCE, AND LEUKEMIA RISK – Am J Epidemiol Vol. 143, No. 2, 1996

Despite the special working environment and exposures of airline pilots, data on risk of death and cancer incidence in this occupational group are limited. The authors investigated a cohort of 2,740 Air Canada pilots who contributed 62,449 person-years of observation. All male pilots employed for at least 1 year on and since January 1, 1950, were studied.

The cutoff date for outcome information was December 31, 1992. Standardized morality ratio (SMR) and standardized incidence ration (SIR) were used to compare mortality rates and cancer incidence rates of the cohort with the respective Canadian population rates. Ninety percent confidence intervals of the SMR and SIR were calculated.

Statistically significant decreased mortality was observed for all causes (SMR = 0.63, 90% confidence interval (Cl) 0.56-0.70), for all cancers (SMR = 0.61, 90% Cl 0.48-0.76), and for all noncancer diseases (SMR = 0.53, 90% Cl 0.45-0.62). Mortality from aircraft accidents was significantly raised (SMR = 26.57, 90% Cl 19.3-35.9). Significantly decreased cancer incidents was observed for all cancers (SIR = 0.71, 90% Cl 0.61-0.82), rectal cancer (SIR = 0.42, 90% Cl 0.14-0.96), lung cancer (SIR = 0.28, 90% Cl 0.16-0.46), and bladder cancer (SIR = 0.36 90% Cl 0.12-0.82). Prostate cancer (SIR = 1.87, 90% Cl 1.38-2.49) and acute myeloid leukemia (SIR = 4.72, 90% Cl 2.05-9.31) were significantly increased.

The preferred relative risk model for radiation-induced nonchronic lymphoid leukemia (Beir V report) was applied to the cohort by using published estimates of in-flight radiation exposures.

The estimated relative risk ranged from 1.001 to 1.06 and did not differ significantly from the observed SIR (SIR = 1.88, 90% Cl 0.80-3.53). However, the incidence rate of acute myeloid leukemia was significantly increased. Monitoring of in-flight radiation exposure and long-term follow-up of civil aviation crew members is needed to further assess cancer incidence and leukemia risk in this special occupational group.


WHO Collaborating Center, University Bielefeld, 33501 Bielefeld, Germany – MORTALITY FROM CANCER AND OTHER CAUSES AMONG AIRLINE CABIN ATTENDANTS IN GERMANY – 1960-1997 – American Journal of Epidemiology – Vol. 156, No.6, 2002

Airline cabin attendants are exposed to several potential occupational hazards, including cosmic radiation. Little is known about the mortality pattern and cancer risk of these persons. The authors conducted a historical cohort study among cabin attendants who had been employed by two German airlines in 1953 or alter. Mortality follow-up was completed through December 31, 1997.

The authors computed standardized mortality ratios (SMRs) for specific causes of death using German population rates. The effect of duration of employment was evaluated with Poisson regression. The cohort included 16,014 women and 4,537 men (approximately 250,000 person-years of follow up). Among women, the total number of deaths (n = 141) was lower than expected (SMR = 0.79, 95% confidence interval (Cl): 0.67, 0.94). The SMR for all cancers (n = 44) was 0.79 (95% Cl;0.54, 1.17) and the SMR for breast cancer (n = 19) was 1.28 (95% Cl: 0.72, 2.20). The SMR did not increase with duration of employment. Among men, 170 deaths were observed (SMR = 1.10, 95% Cl: 0.94, 1.28).

The SMR for all cancers (n = 21) was 0.71 (95% Cl: 0.41, 1.18). The authors found a high number of deaths from acquired immunodeficiency syndrome (SMR – 40; 95% Cl: 28.9, 55.8) and from aircraft accidents among the men. In this cohort, ionizing radiation probably contributed less to the small excess in breast cancer mortality than reproductive risk factors. Occupational causes seem not to contribute strongly to the mortality of airline cabin attendants. Am J Epidemiol 2002; 156:556-65. Abbreviations: AIDS, acquired immunodeficiency syndrome; Cl, confidence interval; SIR, standardized incidence ratio; SMR, standardized mortality ratio.


E A Whelan – CANCER INCIDENCE IN AIRLINE CABIN CREW – Occupational Environmental Medicine, 2003. 60

Evidence that flight crew are at increased risk for certain types of cancer is growing although epidemiological evidence remains inconclusive. Epidemiological studies of morality and cancer incidence in flight crew have been reviewed recently, but in the past 2-3 years, 10 new studies of pilots or cabin crew have been published, the majority of which result from a combined effort underway by the European Community. These studies include three mortality studies and seven cancer incidence studies. Overall, the reports suggest that pilots are at increased risk of malignant melanoma, non-melanoma skin cancer, and possibly acute myeloid leukemia, and that cabin crew are at increased risk for breast cancer and malignant melanoma.

V Rafnsson, J Hrafnkelsson, H Tulinius, B Sigurgeirsson, J Hjaltalin Olafsson – RISK FACTORS FOR CUTANEOUS MALIGNANT MELANOMA AMONG AIRCREWS AND A RANDOM SAMPLE OF THE POPULATION - Occupational Environmental Medicine 2003; 60, 815-820

Aims:
To evaluate whether a difference in the prevalence of risk factors for malignant melanoma in a random sample of the population and among pilots and cabin attendants could explain the increased incidence of malignant melanoma which had been found in previous studies of aircrews.

Methods:
A questionnaire was used to collect information on hair colour, eye colour, freckles, number of naevi, family history of skin cancer and naevi, skin type, history of sunburn, sunbed, all sunscreen use, and number of sunny vacations.

Results:
The 239 pilots were all males and there were 856 female cabin attendants, which were compared with 454 males and 1464 females of the same age drawn randomly from the general population. The difference in constitutional and behavioural risk factors for malignant melanoma between the aircrews and the population sample was not substantial. The aircrews had more often used sunscreen and had taken more sunny vacations than the other men and women. The predictive values for use of sunscreen were 0.88 for pilots and 0.85 for cabin attendants and the predictive values for sunny vacation were 1.36 and 1.34 respectively.

Conclusion:
There was no substantial difference between the aircrew and the random sample of the population with respect to prevalence of risk factors for malignant melanoma. Thus it is unlikely that the increased incidence of malignant melanoma found in previous studies of pilots and cabin attendants can be solely explained by excessive sun exposure.


A Linnersojo, N Hammar, B-G Dammstrom, M Johansson, H Eliasch – CANCER INCIDENCE IN AIRLINE CAB CREW: EXPEREINCE FROM SWEDEN – Occup Environ Med 2003; 60: 810-814

Aims:
To determine the cancer incidence in Swedish cabin crew.

Methods:
Cancer incidence of cabin crew at the Swedish Scandinavian Airline System (SAS) (2324 women and 632 men) employed form 1957 to 1994 was determined during 1961-96 from the Swedish Natioanl Cancer Register. The cancer incidence in cabin crew was compared with that of the general Swedish population by comparing observed and expected number of cases through standardized incidence ratios (SR). A nested case-control study was performed, including cancer cases diagnosed after 1979 and four control per case matched by gender, age, and calendar year.

Results:
The SIR for cancer overall was 1.01 (95% Cl 0.78 to 1.24) for women and 1.16 (95% CI 0.76 to 1.55) for men. Both men and women had an increased incidence of malignant melanoma of the skin (SIR 2.18 and 3.66 respectively) and men of non-melanoma skin cancer (SIR 4.42). Female cabin attendants had a non-significant increase of breast cancer (SIR 1.30; 95% Cl 0.85 to 1.74). No clear associations were found between length of employment or cumulative block hours and cancer incidence.

Conclusions:
Swedish cabin crew had an overall cancer incidence similar to that of the general population An increased incidence of malignant melanoma and non-melanoma skin cancer may be associated with exposure to UV radiation, either at work or outside work. An increased risk of breast cancer in female cabin crew is consistent with our results and may in part be due to differences in reproductive history.


V Rafnsson, P Sulem, H Tulinius, J Hrafnkelsson – BREAST CANER RISK IN AIRLINE CABIN ATTENDANTS: A NESTED CASE-CONTROL STUDY IN ICELAND – Occup Environ Med 2003; 60: 807-809

Aims:
To investigate whether length of employment as a cabin attendant was related to breast cancer risk, when adjusted for reproductive factors.

Methods:
Age matched case-control study nested in a cohort of cabin attendants. The cases were found from a nationwide cancer registry (followed up to end of year 2000) and the reproductive factors (age at first childbirth and number of children) from a registry of childbirth, in both instances by record linkage with the cabin attendants’ identification numbers. The employment time of the cabin attendants at the airline companies and the reproductive factors had been systematically recorded prior to the diagnosis of breast cancer in the cohort. A total of 35 breast cancer cases and 140 age matched controls selected from a cohort of 1532 female cabin attendants were included in the study.

Results:
The matched odds ratio from conditional logistic regression of breast cancer risk among cases and controls of cabin attendants was 5.24 (95% Cl 1.58 to 17.38) for those who had five or more years of employment before 1971 compared with those with less than five years of employment before 1971, adjusted for age at first childbirth and length of employment from 1971 or later.

Conclusions:
The association between length of employment and risk of breast cancer, adjusted for reproductive factors, indicates that occupational factors may be an important cause of breast cancer among cabin attendants; the association is compatible with a long induction period.


Maria Blettner, Hazjo Zebb, Anssi Auvinen, Terri J Ballard, Massimiliano Caldora, Harald Eliasch, Maryanne Gundestrup, Tor Haldorsen, Niklas Hammar, Gael P Hammer, David Irvine, Ingo Langner, Alexandra Paridou, Eero Pukkala, Vilhjalmur Rafnsson, Hans Torm, Hrafn Tulinius, Ulf Tveten and Anastasia Tzonou – MORTALITY FROM CANCER AND OTHER CAUSES AMONG MALE AIRLINE COCKPIT CREW IN EUROPE – Int. J. Cancer: 106 946-952 (2003).

Airline pilots and flight engineers are exposed to ionizing radiation of cosmic origin and other occupational and life-style factors that may influence their health status and mortality. In a cohort study in 9 European countries we studied the mortality of this occupational group. Cockpit crew cohorts were identified and followed-up in Denmark, Finland, Germany, Great Britain, Greece, Iceland, Italy, Norway and Sweden, including a total of 28,000 persons. Observed and expected deaths for the period 1960-97 were compared based on national mortality rates.

The influence of period and duration of employment was analyzed in stratified and Poisson regression analyses. The study comprised 547,564 person-years at risk, and 2,244 deaths were recorded in male cockpit crew (standardized mortality ration (SMR) = 0.64, 95% confidence interval (Cl) = 0.61-0.67). Overall cancer mortality was decreased (SMR – 0.68; 95% Cl = 0.63-0.74). We found an increased mortality from malignant melanoma (SMR = 1.78, 95% Cl – 1.15-2.67) and a reduced mortality from lung cancer (SMR = 0.53, 95% Cl = 0.44-0.62).

No consistent association between employment period or duration and cancer mortality was observed. A low cardiovascular mortality and an increased mortality caused by aviation accidents were noted. Our study shows that cockpit crew have a low overall mortality. The results are consistent with previous reports of an increased risk of malignant melanoma in airline pilots. Occupational risk factors apart from aircraft accidents seem to be of limited influence with regard to the mortality of cockpit crew in Europe.


Hajo Zeeb, Maria Blettner, Ingo Langner, Gaël P Hammer, Terri J Ballard, Mariano Santaquilani, Maryanne Gundestrup, Hans Storm, Tor Haldorsen, Ulf Tveten, Niklas Hammar, Annette Linnersjo, Emmanouel Velonakis, Anastasia Tzonou, Anssi Auvinen, Eero Pukkala, Vilhjálmur Rafnsson, and Jón Hrafnkelsson – MORTALITY FROM CANCER AND OTHER CAUSES AMONG AIRLINE CABIN ATTENDANTS IN EUROPE: A COLLABORATIVE COHORT STUDY IN EIGHT COUNTRIES – Am J Epidemiol 2003; 158: 35-46

There is concern about the health effects of exposure to cosmic radiation during air travel. To study the potential health effects of this and occupational exposures, the authors investigated mortality patterns among more than 44,000 airline cabin crew members in Europe.

A cohort study was performed in eight European countries, yielding approximately 655,000 person-years of follow-up. Observed numbers of deaths were compared with expected numbers based on national mortality rates. Among female cabin crew, overall mortality (standardized mortality ration(SMR) = 0.80, 95% confidence interval (Cl): 0.73, 0.88) and all-cancer mortality (SMR = 0.78, 95% Cl: 0.66, 0.95) were slightly reduced, while breast cancer mortality was slightly but nonsignificantly increased (SMR – 1.11, 95% Cl: 0.82, 1.48). In contrast, overall mortality (SMR = 1.09, 95% Cl: 1.00, 1.18) and mortality from skin cancer (for malignant melanoma, SMR = 1.93, 95% Cl: 0.70, 4.44) among male cabin crew were somewhat increased.

The authors noted excess mortality from aircraft accidents and from acquired immunodeficiency syndrome in males. Among airline cabin crew in Europe, there was no increase in mortality that could be attributed to cosmic radiation or other occupational exposures to any substantial extent. The risk of skin cancer among male crew members requires further attention. Abbreviations: AIDS, acquired immunodeficiency syndrome, Cl, confidence interval, ESCAPE, European Study of Cancer Risk among Airline Pilots and Cabin Crew, SMR, standardized mortality ratio.


Eero Pukkala, Rafael Aspholm, Anssi Auvinen, Harald Eliasch, Maryanne Gundestrup, Tor Haldorsen, Niklas Hammar, Jón Hrafnkelsson, Pentti Kyyronen, Anette Linnersjo, Viljhálmur, Rafnsson, Hans Storm, and Ulf Tveten – CANCER INCIDENCE AMONG 10, 211 AIRLINE PILOTS: A NORDIC STUDY – Aviation, Space and Environmental Medicine Vo. 74, No. 7, July 2003

Background:
Commercial airline pilots are exposed to cosmic radiation and other potentially carcinogenic elements during work and leisure activities.

Hypothesis:
Work-related factors affect cancer pattern of the pilots.

Methods:
A cohort of 10,051 male and 160 female airline pilots from Denmark, Finland, Iceland, Norway, and Sweden was followed for cancer incidence through the national cancer registries. There were 177,000 person-years at follow-up, 51,000 of them accumulated after 20 yr since the time of first employment. Standardized incidence ratios (SIRs) were defined as ratios of observed over expected numbers of cases based on national cancer incidence rates. Dose-response analyses were done with Poisson regression method.

Results:
Among male pilots, there were 466 cases of cancer diagnosed vs. 456 expected. The only significantly increased SIRs concerned skin cancer: melanoma 2.3 (95% Cl 1.7-3.0), squamous cell cancer 2.1 (1.7-2.8), and basal cell carcinoma 2.5 (1.9-3.2). The relative risk of skin cancers increased with the time since first employment, the number of flight hours, and the estimated radiation dose. There was an increase in the relative risk of prostate cancer with increasing number of flight hours in long-distance aircraft (p trend 0.01). No increased incidence was found for acute myeloid leukemia or brain cancer which were of interest a priori based on earlier studies.

Conclusions:
This large study, based on reliable cancer incidence data, showed an increased incidence of skin cancer. It did not indicate a marked increase in cancer risk attributable to cosmic radiation although some influence of cosmic radiation on skin cancer cannot be entirely excluded.


Lantos P, Fuller N, Bottollier-Depois J-F - METHODS FOR ESTIMATING RADIATION DOSES RECEIVED BY COMMERCIAL AIRCREW – Aviation, Space, and Environmental Medicine, Vol. 74, No. 7 – July 2003

Introduction:
Radiation doses received onboard aircraft are monitored in Europe to protect aircrew in accordance with a European Union directive. The French Aviation Authorities have developed a system called SIEVERT, using calculation codes to monitor effective radiation doses.

Methods:
For the galactic cosmic ray component, a 3-D world map of effective dose rates is computed using available operational codes. Detailed flight plans are used to ensure sufficient precision. For the solar particle event component, a semi-empirical model called SiGLE has been developed to calculate a time-dependent map of effective dose rates in the course of the event. SiGLE is based on particle transport code results and measurements during solar particle events onboard Concorde airplanes.

Results:
We present a comparison of the calculated effective radiation dose and measured dose equivalent for various flights onboard Air France aircraft. The agreement is within 15%, which is about the precision of the state-of-the-art dosimetric measurements. Meteorological effects on the dose calculation appear to be negligible. Preliminary results based on solar particle events observed since 1942 with ionization chambers and neutron monitors are given.

Conclusions: The present analysis shows that for the galactic cosmic ray component, monthly world maps based on neutron monitor observations are sufficient to ensure a precision of about 20% on the dose estimate for each flight. For the past 40 yr, according to the model SiGLE, none of the solar events has given an effective radiation dose larger than 1 mSv of flights on the most exposed routes.

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