PubMed · 4406065
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1974-04-15. Letter: Wind.. https://pubmed.ncbi.nlm.nih.gov/4406065/
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Surveys indicate over 50 million Americans, mostly women, currently operate video display terminals (VDTs) at home or in the workplace. Recent epidemiological studies reveal more than 75% of approximately 30 million American temporomandibular disorder (TMD) sufferers are women. What does the VDT and TMD have in common besides an affinity for the female gender? TMD is associated with numerous risk factors that commonly initiate sympathetic nervous system and stress hormone response mechanisms resulting in muscle spasms, trigger point formation, and pain in the head and neck. Likewise VDT operation may be linked to three additional sympathetic nervous system irritants including: (1) electrostatic ambient air negative ion depletion, (2) electromagnetic radiation, and (3) eyestrain and postural stress associated with poor work habits and improper work station design. Additional research considering the roles these three factors may play in the etiology of TMD and other myofascial pain problems is indicated. Furthermore, dentists are advised to educate patients as to these possible risks, encourage preventive behaviors on the part of employers and employees, and recommend workplace health, safety, and ergonomic upgrades when indicated.
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Adult male Long-Evans rats were exposed to negatively charged air ions at high concentrations (7 x 10(5)/cm3) for six days. Sham-exposed rats were treated identically except that the source of ions was not activated. At the end of the exposure, the latency of the tail-flick reflex was measured in each rat before and 30 and 60 min after an injection of morphine sulphate. The tail-flick reflex was initiated by thermal stimulation. Two heat settings were employed, the lower considered to impart a submaximal and the higher a maximal thermal stimulus. Three morphine doses were tested: 0.5, 1.0, and 1.5 mg/kg. Statistically significant differences between ion-exposed and sham-exposed rats were observed in tail-flick latencies 30 min after the administration of the two lower doses, but not after the highest dose of morphine sulphate. These differences were found at both intensities of thermal stimulation. Tail-flick latencies measured in each group prior to morphine injection were not affected by negative-ion exposure. The data indicate that exposure of rats to negative air ions tends to inhibit the action of morphine on the latency of the tail-flick reflex at morphine doses below 1.0 mg/kg.