Narayanan SN, Kumar RS, Potu BK, Nayak S, Bhat PG, Mailankot M. Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats. Ups J Med Sci. Jan 23, 2010. Ahead of print.

There is concern in society that the frequent daily use of cellular phones will lead to increased exposure to radio-frequency electromagnetic radiation (RF-EMR) and its associated health hazards.  Studies have demonstrated that long term exposure to this type of radiation can result in impaired spatial memory in Wistar rats.  Exposed to the radiation in sufficient doses, they take longer to progress through a maze.    

The objective of this study was to determine the effects of mobile phone exposure on brain cell structure and passive avoidance behaviour in Wistar rats.

Two separate groups of 12 rats each were used in the study.  Each rat was placed in a separate cage.  One group received cellular phone calls. The other didn’t.  Those that did were given 50 calls within the space of an hour each day for four weeks.  Each call was 45 seconds long, placed in vibratory mode with no ring tone with an average exposure of 0.9GHz/1.8GHz per cell phone.  At the end of four weeks of exposure, six rats from each group were tested for passive avoidance behaviour.  The rats were placed in a cage containing two compartments, one smaller and unlit, the other larger and well-lit.  The test was divided into three phases.  In the first phase, each rat was allowed to explore the entire apparatus three times for three minutes each.  In the second phase they were put in the unlit chamber and subjected to three strong foot shocks.   In the final phase, they were returned to the two compartments 24 and 48 hours after the foot shock treatment.  Rats that refrained from entering the unlit chambers were deemed to have good spatial memory, while those who re-entered the unlit chambers relatively quickly were considered to have impaired spatial memory.  Six rats from each group were sacrificed and changes in brain morphology related to learning and memory were investigated. 

Although the exposed rats took longer to enter the dark chamber during phase one, after the shock trial, they entered the chamber much faster than the unexposed group, indicating that the parts of their brains associated with memory retention had been adversely affected by the cellular phone calls. Indeed, a comparison of stained brain cells between the two groups revealed significant changes in brain cell morphology.

Interpretation and Limitations
Given that rats by nature prefer dim lighting and would normally defer to the unlit chambers, the fact that some of them modified their behaviour as a result of the trauma of the foot shocks suggests that they do have spatial memory retention.  The authors believe that there is a strong correlation between the odd behaviour of the rats exposed to radiation emitted by cellular phones who returned to the unlit chambers in spite of the trauma they had experienced, and the damage seen in the cells of their brains. It would be an interesting and worthwhile exercise to both increase the number of animals used in this study, and conduct it among other species to see if the same results recur.  

This study suggests that RF-EMR exposure for one hour per day for 4 weeks alters passive avoidance behaviour in Wistar rats and changes brain cell morphology.

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