Biomedical subjects

J S Nicholas

Publications and source records attributed to J S Nicholas.

12 recordsLinked to original sources

PubMed2003

Stable chromosome aberrations and ionizing radiation in airline pilots.

INTRODUCTION: The purpose of this study was to determine the frequency of translocations and insertions in the blood of long-term pilots in relation to estimated cumulative radiation dose received while flying, and to compare that to the frequency in a group of similarly aged men without a history of frequent airline travel. METHODS: Healthy, non-smoking male pilots aged 40-60 yr were recruited from a single airline. Non-pilot controls were recruited from healthy, non-smoking professional males in the same age range and without a history of frequent flying. Eligibility was determined based on screening surveys. Career pilot radiation doses were calculated individually using airline flight profiles, personal flight history, and the CARI computer program. Translocation frequency was determined using fluorescence in situ hybridization. RESULTS: Blood samples for chromosome analysis were provided by 19 individuals. The mean number of metaphases counted per subject was 2802 in the pilots and 3000 in the controls. The mean number of translocations per cell (genome equivalent) was significantly higher among the pilots (mean +/- SE; 0.0031 +/- 0.0008) than among the controls (0.0010 +/- 0.0003) (p = 0.03, Mann-Whitney U test). However, within the 26 to 72 millisievert range encountered in this study, observed values among the pilots did not follow the dose-response pattern expected based on available models for chronic low dose radiation exposure. CONCLUSIONS: There was a statistically significant higher number of translocations per cell among pilots than among controls, although the expected dose-response relationship for radiation was not observed among the pilots.

Adult↗

PubMed2001

Health among commercial airline pilots.

BACKGROUND: The airline pilot works within a complex exposure environment that may present physiological challenges to long-term health. METHODS: This study investigated self-reported disease outcomes among a large group of active and retired commercial airline pilots in the United States and Canada. A survey methodology was used, including the collection of historical information. RESULTS: Of 10,678 surveys mailed, 6609 were returned (6533 men, 63 women). Given the limitations of survey methodology, increased disease rates among pilots were suggested for melanoma, motor neuron disease, and cataracts. However, rates for other diseases were in general lower than those for the U.S. population. CONCLUSIONS: Further study has been initiated to verify and follow reported cases, to expand the study to a larger group, and to collect more in-depth information on flight histories, occupational exposures, and lifestyle factors.

Adolescent↗

PubMed2000

Flight deck magnetic fields in commercial aircraft.

BACKGROUND: Airline pilots are exposed to magnetic fields generated by the aircraft's electrical system. The objectives of this study were (1) to directly measure flight deck magnetic fields in terms of personal exposure to the pilots when flying on different aircraft types over a 75-hour flight-duty month, and (2) to compare magnetic field exposures across flight deck types and job titles. METHODS: Measurements were taken using personal dosimeters carried by either the Captain or the First Officer on Boeing 737/200, Boeing 747/400, Boeing 767/300ER, and Airbus 320 aircraft. RESULTS: Approximately 1,008 block hours were recorded at a sampling frequency of 3 seconds. Total block time exposure to the pilots ranged from a harmonic geometric mean of 6.7 milliGauss (mG) for the Boeing 767/300ER to 12.7 mG for the Boeing 737/200. CONCLUSIONS: Measured flight deck magnetic field levels were substantially above the 0.8-1 mG level typically found in the home or office and suggest the need for further study to evaluate potential health effects of long-term exposure.

Aircraft↗

PubMed2000

Galactic cosmic radiation exposure of pregnant flight crewmembers.

BACKGROUND: In recommending the occupational dose limit of ionizing radiation for pregnant women, the International Commission on Radiological Protection apparently assumes that the dose to the conceptus from ionizing radiation exposure is about half the dose at the surface of the mother's abdomen. METHODS: To test this assumption with respect to galactic cosmic radiation, calculations were made using FAA computer program CARI-LF2, which calculates equivalent doses from galactic cosmic rays at selected depths in soft tissue at any specified location in the atmosphere or on user-entered flight profiles. RESULTS: The calculations showed that the equivalent dose of galactic radiation was almost the same at all depths. CONCLUSIONS: Thus the assumption of considerable shielding of the conceptus being provided by the woman's body is not correct with respect to galactic cosmic radiation, the principal type of radiation to which aircrews are exposed. The effective dose as calculated with FAA computer program CARI-5E, which calculates effective dose in an anthropomorphic phantom at any specified location in the atmosphere or on user-entered flight profiles, was found to be a good estimate of the equivalent dose at the depth of the conceptus.

Aerospace Medicine↗

PubMed1998

Cosmic radiation and magnetic field exposure to airline flight crews.

BACKGROUND: Flight crews are exposed to elevated levels of cosmic radiation and to magnetic fields generated by the aircraft's electrical system. The purpose of this study was to quantify these two occupational exposures. METHODS: Magnetic fields were measured during 37 flights (23 in the cockpit and 14 in the cabin) using an Emdex Lite personal dosimeter. All cockpit measurements were taken on the B737/200. Cabin measurements were taken in several aircraft types, including the B737, B757, DC9, and L1011. Cosmic radiation was computer estimated for 206 flights using the Federal Aviation Administration's program CARI-3C. RESULTS: Magnetic field levels in the cockpit had a mean value of approximately 17 milliGauss (mG), while cabin measurements were lower (mean values of approximately 3 or less in economy, 6 in first class, 8 in front serving areas). Cosmic radiation equivalent dose rates to bone marrow and skeletal tissue ranged from 0.3 to 5.7 microsieverts per hour. CONCLUSIONS: Elevated magnetic field levels in front serving areas and the cockpit suggest the need for further study to evaluate long-term exposure to flight crew members who work in these areas. Cosmic radiation levels are well below occupational limits for adults, but may require some pregnant flight crew members to adjust their flying time or routes.

Aerospace Medicine↗

PubMed1998

Mortality among US commercial pilots and navigators.

The airline industry may be an occupational setting with specific health risks. Two environmental agents to which flight crews are known to be exposed are cosmic radiation and magnetic fields generated by the aircraft's electrical system. Other factors to be considered are circadian disruption and conditions specific to air travel, such as noise, vibration, mild hypoxia, reduced atmospheric pressure, low humidity, and air quality. This study investigated mortality among US commercial pilots and navigators, using proportional mortality ratios for cancer and noncancer end points. Proportional cancer mortality ratios and mortality odds ratios were also calculated for comparison to the proportional mortality ratios for cancer causes of death. Results indicated that US pilots and navigators have experienced significantly increased mortality due to cancer of the kidney and renal pelvis, motor neuron disease, and external causes. In addition, increased mortality due to prostate cancer, brain cancer, colon cancer, and cancer of the lip, buccal cavity, and pharynx was suggested. Mortality was significantly decreased for 11 causes. To determine if these health outcomes are related to occupational exposures, it will be necessary to quantify each exposure separately, to study the potential synergy of effects, and to couple this information with disease data on an individual basis.

Aerospace Medicine↗

PubMed1987