Effects of 7 Hz-modulated 450 MHz electromagnetic radiation on human performance in visual memory tasks.

Lass L, Tuulik V, Ferenets CR, Riisalo R, Hinrikus H

Int. J. Rad. Biol. 78: 937-944, 2002

Purpose: The aim was to examine low-level 7 Hz-modulated 450 MHz radiation effects on human performance in visually presented neuropsychological tasks associated with attention and short-term memory.

Materials and methods: A homogeneous group of 100 subjects (37 female, 63 male) were randomly assigned to either the exposed (10-20 min, 0.158mW cm^{- 2}) or the sham-exposed group. A battery of three different tests measured attention and shortterm memory.

Task 1 involved alternately selecting black digits from 1 to 25 in ascending order and white digits from 24 to 1 in descending order. The time spent on the task and the number of errors were recorded and analysed.

Task 2 involved viewing a picture of 12 objects during 3 s, followed by a list of 24 words. The subject was required to select words representing previously presented objects.

In task 3, an array of letters in 10 rows (60 in each row) was presented, and the subject was required to identify all examples of a particular two-letter combination.

Results: The results of tasks 1 and 3 showed a significant increase in variances of errors (p <0.05) in the exposed versus the sham-exposed group. The results of task 2 indicated a significant decrease in errors (p <0.05) in the exposed group.

Conclusions: The data provide additional evidence that acute low-level exposure to microwaves modulated at 7 Hz can affect cognitive processes such as attention and short-term memory.