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Haematopoiesis of Rat after Whole Body Radiofrequency Microwave Irradiation

Introduction and Objective In numerous studies of high-level (thermal) radiofrequency microwave (RF/MW) irradiaton, certain haematopoietic changes have been observed in experimental animals (1). Considering insufficient and mainly contradictory data of potential non-thermal and athermal effects of RF/MW on the animal blood-forming and circulating blood cells, we have realized investigation to determine whether subacute exposure to low-level RF/MW field influences on differentiation, maturation and proliferation of rat bone marrow cells. Material and Methods Adult male Wistar rats were exposed to 2450 MHz cw (continuous wave) RF/MW field 2 hours daily, 7 days per week. The power density of the field was averaged to 5-15 mW/cm2 corresponding to approximate specific absorption rates (SARs) of 1-2 W/kg. According to recent literature, SARs of this range exclude thermal stress in rats (2). During the treatment regimen, animals were placed in individual Plexiglas cages and exposed to RF/MW source (modified Micro-Chef MoulinexŽ generator) in the far field. A group of forty exposed animals was divided into the four subgroups in order to be irradiated for 2x2, 8x2, 15x2 and 30x2 hours. Food and water were withheld to prevent aberrations in the field. The rectal body temperature was measured before and after exposure treatment to eliminate biased thermal effects on observed variables. After ether anaesthesia, experimental animals were euthanatized on the final irradiation day of each treated subgroup. The control group of twenty four animals were also divided in four subgroups to be sacrifited on indicated days. Bone marrow samples were isolated from one femur of each animal. Both the proximal and distal ends of the carcass femur were cut off and the bone marrow was gently flushed out with buffered physiological saline and foetal calf serum (1:1). Preparation of the bone marrow cells was applied according to Mazure’s procedure (3). Microscopes slides of bone marrow smears were staining with May-Grünwald and Giemsa solutions. There were estimated absolute and relative cell count of erythropoietic, myelopoietic and lymphopoietic cells in bone marrow. Statistical analysis were made using Mann-Whitney test (p values less than 0,05 were considered significant). Results The absolute count of lymphoblasts significantly decreased in the exposed animal group after 8, 15 and 30 days of irradiation, showing time- and dose-dependencing (Figure 1). So far, the other haematopoietic variables did not show consistent alternations. Figure 1: Absolute lymphoblast count (medians) of control and irradiated animal groups Discussion and Conclusions The concern about long-term residential and occupational exposure to artificial radiofrequency-microwave fields demands intensive laboratory and epidemiological studies. Alternation of generatived tissue such as the bone marrow, could indicate possible adverse health effects of RF/MW. Our results suggest that subacute whole body low-power level of RF/MW irradiation (i.e. 2450 MHz, cw) effected lymphocytopoiesis by decreasing lymphoblast cell count in rat bone marrow. This study contributes to recently published data of other investigations that have revealed significantly decreased lymphocytes in peripheral blood of rats (4). References 1. World Health Organization (WHO). Electromagnetic Fields (300 Hz to 300 GHz). Environmental Health Criteria No. 137. Geneva: WHO, 1993. 2. IEGMP (Independent Expert Group on Mobile Phones): Mobile phones and health. NRPB 2000. Available on the website at http://www.iegmp.org.uk 3. Mazur L. Induction of micronucleated erythrocytes by MEA, AET, WR-2721 and X-rays. Mutat Res Environ 1995, 334:317-322. 4. Trosic I, Matausic-Pisl M, Radalj Z, Prlic I. Animal study of electromagnetic field biological potency. Arh hig rada toksikol 1999, 1:5-11.

rats; haematopoiesis; microwave; irradiation

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