Thresholds of microwave-evoked warmth sensations in human skin

Blick, Dennis W.; Adair, E. R.; Hurt, W. D.; Sherry, C. J.; Walters, Thomas J.; Merritt, James H.

doi:10.1002/(sici)1521-186x(1997)18:6<403::aid-bem1>3.0.co;2-6

Cited by 57 publications

(18 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This mechanism relates to the generation of heat in the tissues that results in the activation of thermal sensors in the skin and elsewhere in the central nervous system. Studies of human thermal sensation generated by RF exposures [e.g., Hendler et al, 1963;Justesen et al, 1982;Blick et al, 1997] reinforce the conclusion that behavioral changes observed in RF exposed animals are thermally motivated. Indeed, measured elevations of surface and deep body temperatures often accompany specific behavioral changes demonstrated in the laboratory setting [Brown et al, 1994].…”

Section: Introductionmentioning

confidence: 89%

Behavioral and cognitive effects of microwave exposure

D'Andrea

Adair

Lorge³

2003

Bioelectromagnetics

Self Cite

View full text Add to dashboard Cite

This paper presents an overview of the recent behavioral literature concerning microwave exposure and discusses behavioral effects that have supported past exposure standards. Other effects, which are based on lower levels of exposure, are discussed as well, relative to setting exposure standards. The paper begins with a brief discussion of the ways in which behavioral end points are investigated in the laboratory, together with some of the methodological considerations pertinent to such studies when radio frequency (RF) exposure is involved. It has been pointed out by several sources that exposure to RF radiation can lead to changes in the behavior of humans and laboratory animals that can range from the perceptions of warmth and sound to lethal body temperatures. Behavior of laboratory animals can be perturbed and, under certain other conditions, animals will escape and subsequently avoid RF fields; but they will also work to obtain a burst of RF energy when they are cold. Reports of change of cognitive function (memory and learning) in humans and laboratory animals are in the scientific literature. Mostly, these are thermally mediated effects, but other low level effects are not so easily explained by thermal mechanisms. The phenomenon of behavioral disruption by microwave exposure, an operationally defined rate decrease (or rate increase), has served as the basis for human exposure guidelines since the early 1980s and still appears to be a very sensitive RF bioeffect. Nearly all evidence relates this phenomenon to the generation of heat in the tissues and reinforces the conclusion that behavioral changes observed in RF exposed animals are thermally mediated. Such behavioral alteration has been demonstrated in a variety of animal species and under several different conditions of RF exposure. Thermally based effects can clearly be hazardous to the organism and continue to be the best predictor of hazard for homosapiens. Nevertheless, similar research with man has not been conducted. Although some studies on human perception of RF exist, these should be expandedto include a variety of RF parameters.

show abstract

Section: Introductionmentioning

confidence: 89%

Behavioral and cognitive effects of microwave exposure

D'Andrea

Adair

Lorge³

2003

Bioelectromagnetics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The thresholds for perception of microwave energy have been measured by Blick et al (1997) for brief (10 s) exposure to microwave energy (2.45-94 GHz) over an area of 0.024 m 2 on the backs of human volunteers (Table 3). A thermal model shows that the temperature rise at the skin surface at the threshold for perception in these experiments is in the range of about 0.06°C over this entire frequency range.…”

Section: Perception Of Warmth and Thermal Painmentioning

confidence: 99%

Thermal Mechanisms of Interaction of Radiofrequency Energy With Biological Systems With Relevance to Exposure Guidelines

Foster

Gläser²

2007

Health Physics

View full text Add to dashboard Cite

This article reviews thermal mechanisms of interaction between radiofrequency (RF) fields and biological systems, focusing on theoretical frameworks that are of potential use in setting guidelines for human exposure to RF energy. Several classes of thermal mechanisms are reviewed that depend on the temperature increase or rate of temperature increase and the relevant dosimetric considerations associated with these mechanisms. In addition, attention is drawn to possible molecular and physiological reactions that could be induced by temperature elevations below 0.1 degrees, which are normal physiological responses to heat, and to the so-called microwave auditory effect, which is a physiologically trivial effect resulting from thermally-induced acoustic stimuli. It is suggested that some reported "nonthermal" effects of RF energy may be thermal in nature; also that subtle thermal effects from RF energy exist but have no consequence to health or safety. It is proposed that future revisions of exposure guidelines make more explicit use of thermal models and empirical data on thermal effects in quantifying potential hazards of RF fields.

show abstract

“…Humans (22)(23)(24)(25) show sensitivities to temperature changes in the skin of Ϸ0.02°C near the neutral point of Ϸ38°C. There is both temporal summation and area integration; to a good approximation, a warm-cold response is proportional to the time integral of the temperature signal up to a period of 3 s and to a spatial summation up to areas which vary over the body but are of the magnitude of 25 cm 2 on the forearm or back.…”

Section: Sensitivitymentioning

confidence: 99%

A model of the detection of warmth and cold by cutaneous sensors through effects on voltage-gated membrane channels

Adair

1999

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Warmth and cold sensations are known to derive from separate warm and cold cutaneous thermoreceptors in the form of differentiated afferent nerves. The firing rate of warm-sensing nerves increases as the temperature increases; the firing rate of coldsensing nerves increases if the temperature is reduced. I postulate that the primary sensitivity of the warm sensors derives from voltage-gated Ca 2؉ membrane channels configured such that an increase in temperature opens channels and increases the ion influx while a reduction in temperature increases the ion influx through voltage-gated Na ؉ channels in the cold sensory nerve ends. In either case, the initial cation influx causes a small cellular depolarization that further opens Ca 2؉ channels, admitting more cations in a positive feedback process that leads to the depolarization of the membrane, thus initiating an action potential pulse. Monte Carlo calculations based on a well defined model of such processes, which include effects of noise, demonstrate quantitative agreement of the model with an extensive body of data.T he sensations of warmth and cold are known to follow from the excitation of separate warm and cold cutaneous thermoreceptors as measured by the firing rates of the afferent nerves that form the receptors. For each modality, the firing rates depend statically upon temperature, T, and dynamically on the rate of temperature change, dT͞dt, with positive coefficients for warm receptors and negative coefficients for cold receptors (1). Hence, in the homeotherm skin, the firing rate of the afferent nerves that serve the warm-receptors increases with increasing temperature while the firing rate of the nerves that serve the cold sensors is reduced (1-3). The systems adapt to long-term temperature changes and an increase in external calcium concentration results in a feeling of warmth (4, 5).I show, through Monte Carlo calculations that include noise effects, that these properties of the warm-cold sensory system can be understood quantitatively as the consequences of simple characteristics of voltage-gated membrane channels in the sensory nerve systems that admit Ca 2ϩ and Na ϩ cations into afferent nerve cell that generate the observed action pulses.The warm-receptors in mammals appear to be differentiated C-fibers, unmyelinated afferent nerve fibers Ϸ1-2 m in diameter (6, 7), while the cold receptors are differentiated A␦ fibers (8), myelinated axons Ϸ3 m in diameter. The afferent cold fibers differentiate near their end, at the sensory site, into 5 or 10 short unmyelinated fibers (1). The warm-fibers differentiate similarly (9). I assume that the sensory regions consist of these differentiated ''fingers.'' The cold-receptor fingers are found at a depth of Ϸ150 m in the human skin, near the interface between the dermis and epidermis. The warm-receptors may be somewhat deeper (10, 11).The density of receptors in humans varies according to the location, and there are usually more cold sensors than warm sensors. While there are, typically, from one to five c...

show abstract

Thresholds of microwave-evoked warmth sensations in human skin

Cited by 57 publications

References 14 publications

Behavioral and cognitive effects of microwave exposure

Behavioral and cognitive effects of microwave exposure

Thermal Mechanisms of Interaction of Radiofrequency Energy With Biological Systems With Relevance to Exposure Guidelines

A model of the detection of warmth and cold by cutaneous sensors through effects on voltage-gated membrane channels

Contact Info

Product

Resources

About