Thresholds of Pain and Reflex Contraction as Related to Noxious Stimulation

Bioeffects Seen

James D. Hardy, Irving Jacobs, Margaret D. Meixner · 1953

Pain and tissue damage don't always correlate, suggesting harmful biological effects can occur without immediate sensory warning signals.

Plain English Summary

Summary written for general audiences

This 1953 study examined the relationship between tissue damage and pain perception by analyzing when skin temperature reaches the critical threshold of 45°C (113°F) for both pain sensation and thermal damage. Researchers found that while pain and tissue damage often occur together, the relationship is complex - citing battlefield observations where only 50% of severely wounded soldiers reported pain.

Why This Matters

This foundational pain research reveals something crucial for understanding EMF health effects: the disconnect between tissue damage and immediate sensory warning signals. Just as wounded soldiers felt no pain despite severe injuries, EMF exposure may cause biological effects without triggering pain or other obvious symptoms that would alert us to harm. The study's identification of 45°C as the critical temperature threshold for both pain and tissue damage provides a biological benchmark that's relevant today - many EMF devices can heat tissue, and some research suggests non-thermal EMF effects may occur at levels well below this temperature threshold. This challenges the outdated regulatory assumption that if EMF exposure doesn't cause heating, it's automatically safe.

Figures from the Original Paper

Diagrams extracted from the original research document.

graphPage 2 - Figure 1. Pain threshold measurements in 6 subjects for different times of exposure to thermal radiation.
p. 2 of the original PDF

diagramPage 4 - Experimental arrangement for measuring skin temperature during exposure to thermal radiation (Figure 2)
p. 4 of the original PDF

chartPage 5 - AI-described figure: Figure 3. Recordings (double amplitude) of skin temperature before and during exposure to radiant heat showing pain threshold.
p. 5 of the original PDF

chartPage 6 - Figure 4. Average values of skin temperature following exposure to thermal radiation with pain threshold indicated.
p. 6 of the original PDF

graphPage 7 - AI-described figure: Figure 5: Threshold of flexor reflex in paraplegic subject. Rheobase = 40 mcal/sec/cm², smallest stimulus capable of evoking reflex during prolonged exposure.
p. 7 of the original PDF

graphPage 9 - Figure 6 illustrates the influence of stimulus intensity and duration on reflex tail flick in rats and muscle contraction in guinea pigs.
p. 9 of the original PDF

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study

James D. Hardy, Irving Jacobs, Margaret D. Meixner (1953). Thresholds of Pain and Reflex Contraction as Related to Noxious Stimulation.

Show BibTeX

@article{thresholds_of_pain_and_reflex_contraction_as_related_to_noxious_stimulation_g4561,
  author = {James D. Hardy and Irving Jacobs and Margaret D. Meixner},
  title = {Thresholds of Pain and Reflex Contraction as Related to Noxious Stimulation},
  year = {1953},
  
  
}

No DOI on file for this study.

Quick Questions About This Study

The study found that pain is typically elicited when skin temperature reaches approximately 45°C (113°F). This same temperature threshold also marks the point where thermal tissue damage begins to occur.

In battlefield observations of 215 severely wounded men, only about 50% reported pain despite having penetrating wounds. This demonstrates that tissue damage and pain perception don't always correlate directly.

No, the research shows the relationship between tissue damage and pain is complex. The study notes that 'lesions without pain and pain without apparent damage to tissue are common experiences.'

At 45°C, both pain sensation and thermal tissue damage occur simultaneously, suggesting this temperature represents a critical biological threshold where protective mechanisms and actual harm converge in human tissue.

Yes, this study demonstrates that significant tissue damage can occur without triggering pain responses, indicating that the absence of immediate sensory warnings doesn't guarantee tissue safety.