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Effect of Vibration Frequency and Amplitude on Developing Chicken Embryos.
ARMY AEROMEDICAL RESEARCH LAB FORT RUCKER AL
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Fertilized chicken eggs were incubated and exposed repeatedly to whole-body vibration forces with frequencies ranging from 5 to 50Hz, and amplitudes ranging from 0.09 to 4.93 Gzrm5. The timing and duration of exposure were selected to model pregnant women flying Army helicopters 3 hours per day, 5 days per week. Factors associated with chicken embryo mortality were frequency, amplitude, amplitude transmission, and trifling of the exposure. As the magnitude of the exposure increased, mortality increased. No clear HRA threshold values were identified due to the retrospective discovery of protocol problems. The use of an entire tray of eggs as the unit of amplitude measure was invalid due to the differences in vibration amplitude transmission at each egg station. However, mortality thresholds were proposed using a logistic model that controlled for the differences in vibration amplitude noted at various egg stations. No extraneous factors such as month of incubation, flock, and incubator were significant in analysis of variance modeling.
APPROVED FOR PUBLIC RELEASE