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National Research Council (US) Institute for Laboratory Animal Research. The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop. Washington (DC): National Academies Press (US); 2004.

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The Development of Science-based Guidelines for Laboratory Animal Care: Proceedings of the November 2003 International Workshop.

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Breakout Session: Effects of Sound on Research Animals

Leader: Sherri L. Motzel

Rapporteur: Hilton J. Klein

Gaps in our knowledge exist regarding the effects of noise, vibration, and sound for research animals. In this session, Dr. Sherri Motzel, Director of Laboratory Animal Resources at Merck Research Laboratories, presented a scholarly review of the effects of noise, vibration, and sound. The review included definitions, the current regulations and standards for noise, reviews of several relevant studies for rodents and nonhuman primates, and opportunities for noise, sound, and vibration mitigation. Dr. Motzel provided several references and cited relevant studies demonstrating that noise, vibration, and sound can have deleterious effects on behavioral and physiological parameters (Motzel et al. 2001; Sales and Milligan 1992; Sales et al. 1998, 1999).

Sound, which is produced when vibrating objects cause changes in air pressure, varies in duration, frequency (Hz), and magnitude or intensity (decibels, sound pressure level). Laboratory animals vary greatly by species in their ability to detect sound compared with humans. For example, humans detect sound from 20 Hz to 20 kHz, whereas rodent species are much more diverse in their ability to detect sound. Examples of range of detection include the following:

Mouse0.8–100 kHz
Rat0.25-76 kHz
Nonhuman primate (rhesus)0.13-45 kHz
Dog0.04-46 kHz

Thus, animals detect sound inaudible to humans.

The US Animal Welfare Act regulations do not address noise. However, the ILAR Guide for the Care and Use of Laboratory Animals (NRC 1996) includes the recommendation to assess the effects of noise on animals, and to consider noise controls in animal facility design and construction. The Agricultural Guide (APHIS 1998) reflects greater tolerance toward the effects of noise on farm/agricultural animals, based on the few permanent effects reported in the literature cited therein. The Agricultural Guide does, however, include the recommendation that noise control should be considered during facility design. In contrast, the Council of Europe is clearer about the stressful effects of noise on laboratory animals and provides more specific recommendations in noise mitigation and control as well as for facility layout, design, and construction. In summary, regulations and standards for all laboratory animals address noise in a very basic and fundamental manner, yet they do not address the noise issue extensively because of a paucity of data on noise effects in the peerreviewed literature.

Dr. Motzel reviewed sources and types of sound and their effects in animal laboratory settings. Recorded sound levels vary widely but are dependent on species (e.g., barking dogs—99 dB) and on work practices, work cycles, and equipment.

Ultrasonic sound has been recorded from 24 of 39 sources (e.g., video displays, furniture, vacuums, and cage washers) and in some cases exceeds 100 kHz and 122 dB in frequency and intensity. It has been demonstrated clearly that ultrasonic sound creates perturbations in physiological parameters (e.g., heart rate, blood pressure, electroencephalographic changes), behavioral parameters (seizing), and teratogenic effects on laboratory animals.

Sound effects also vary in their impact, depending on the animal species, strain, and age. Dr. Motzel cited clear-cut effects of sound on response to drug treatment, water intake, blood pressure, reproduction, glucose metabolism, and immune function. One study conducted at Merck Research Laboratories by Dr. Motzel and her colleagues demonstrated conclusively that infrasound (1-10 Hz) was responsible for weight loss in CD rats in the study. A malfunctioning air handler was responsible for the source of the subsonic noise, which caused the weight loss. This study and other reports in the literature indicate that much more emphasis should be placed on monitoring and controlling noise levels at multiple frequency and intensity ranges outside human hearing ranges in animal facilities because of the potential for adverse effects on study data and outcomes. Preventive maintenance and facility testing, facility design, and work practices should also be reassessed in the laboratory animal facility in an effort to mitigate adverse noise effects. It was suggested that these strategies are effective for control and mitigation. Sound neutralizers and sound breaks were briefly mentioned as control devices for excessive noise problems.

In summary, the group agreed with Dr. Motzel's assessments that in the context of behavioral and physiological effects, some laboratory animals are more sensitive to noise than humans. These effects are observed across a range of frequency, intensity, and duration that is much broader than in humans. Participants believed that for this reason, the current standards for the human environment may be of limited relevancy and not adequate to protect the integrity of research experiments. Additional in-depth review of the literature combined with relevant research studies to address noise effects in laboratory animals is clearly indicated. Participants agreed that current regulations and guidelines should be revised and updated accordingly.

SELECTED REFERENCES

  1. APHIS [Animal Plant Health Inspection Service] Regulation of agricultural animals (policy 26). In: Animal Care Resource Guide. Washington, DC: US Department of Agriculture; 1998.
  2. Motzel SL, Morrisey RE, Conboy TA, et al. Weight loss in rats associated with exposure to infrasound. Contemp Topics. 1996;35:69.
  3. NRC [National Research Council] Guide for the Care and Use of Laboratory Animals. 7th ed. Washington, DC: National Academy Press; 1996.
  4. Sales GD, Milligan SR. Ultrasound and laboratory animals. Anim Technol. 1992;43:89–98.
  5. Sales GD, Milligan SR, Khirnykh K. Sources of sound in the laboratory animal environment: A survey of the sounds produced by procedures and equipment. Anim Welfare. 1999;8:97–115.
  6. Sales GD, Wilson KJ, Spencer KEV, Milligan SR. Environmental ultrasound in laboratories and animal houses: A possible cause for concern in the welfare and use of laboratory animals. Lab Anim. 1998;22:369–375. [PubMed: 3230874]
Copyright © 2004, National Academy of Sciences.
Bookshelf ID: NBK25435

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