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Effects of microwave exposure and temperature on survival of mice infected with Streptococcus pneumoniae
C G Liddle1, J P Putnam, O H Lewter
1Developmental and Cell Toxicology Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711.
Abstract:
Female CD-1 mice were injected with an LD50 dose of Streptococcus pneumoniae and then exposed to 2.45 GHz (CW) microwave radiation at an incident power density of 10 mW/cm2 (SAR = 6.8 W/kg), 4 h/d for 5 d at ambient temperatures of 19 degrees C, 22 degrees C, 25 degrees C, 28 degrees C, 31 degrees C, 34 degrees C, 37 degrees C and 40 degrees C. Four groups of 25 animals were exposed at each temperature with an equal number of animals concurrently sham-exposed. Survival was observed for a 10-d period after infection. Survival of the sham-exposed animals increased as ambient temperature increased from 19 degrees C-34 degrees C. At ambient temperatures at or above 37 degrees C the heat induced in the body exceeded the thermoregulatory capacity of the animals and deaths from hyperthermia occurred. Survival of the microwave-exposed animals was significantly greater than the shams (approximately 20%) at each ambient temperature below 34 degrees C. Based on an analysis of the data it appears that the hyperthermia induced by microwave exposure may be more effective in increasing survival in infected mice than hyperthermia produced by conventional methods (ie, high ambient temperature). Microwave radiation may be beneficial to infected animals at low and moderate ambient temperatures, but it is detrimental when combined with high ambient temperatures.
Insights
Microwave radiation exposure, combined with Streptococcus pneumoniae infection in mice, improved survival rates at moderate temperatures. However, high ambient temperatures combined with microwave exposure proved detrimental.
Area of Science:
- Environmental Health
- Infectious Disease Research
- Electromagnetic Field (EMF) Biology
Background:
- Streptococcus pneumoniae infection poses a significant health risk.
- The impact of environmental factors, such as microwave radiation and ambient temperature, on infection outcomes is not fully understood.
- Hyperthermia is a known method for potentially managing infections.
Purpose of the Study:
- To investigate the effects of 2.45 GHz (CW) microwave radiation on the survival of mice infected with Streptococcus pneumoniae.
- To determine how varying ambient temperatures influence the efficacy and safety of microwave radiation exposure in infected mice.
- To compare the survival benefits of microwave-induced hyperthermia versus ambient temperature-induced hyperthermia.
Main Methods:
- Female CD-1 mice were infected with a lethal dose (LD50) of Streptococcus pneumoniae.
- Mice were exposed to 2.45 GHz (CW) microwave radiation (10 mW/cm², 6.8 W/kg SAR, 4 h/d for 5 d) across a range of ambient temperatures (19°C to 40°C).
- Survival was monitored for 10 days post-infection, with concurrent sham-exposed control groups at each temperature.
Main Results:
- Sham-exposed mice showed increased survival with rising ambient temperatures from 19°C to 34°C.
- Temperatures at or above 37°C led to hyperthermia and death in sham-exposed mice.
- Microwave-exposed mice exhibited significantly higher survival rates (approx. 20% increase) compared to shams at ambient temperatures below 34°C.
- At high ambient temperatures (≥37°C), microwave exposure was detrimental, exacerbating hyperthermia.
Conclusions:
- Microwave radiation exposure may enhance survival in Streptococcus pneumoniae-infected mice, potentially through induced hyperthermia, particularly at lower ambient temperatures.
- Microwave-induced hyperthermia appears more effective in increasing survival than conventional hyperthermia methods (e.g., high ambient temperature).
- The combination of microwave radiation and high ambient temperatures is detrimental to infected animals due to excessive hyperthermia.