EMF-Portal | In vitro studies of microwave-induced cataract: reciprocity between exposure duration and dose rate for pulsed microwaves

In vitro studies of microwave-induced cataract: reciprocity between exposure duration and dose rate for pulsed microwaves med./bio.

By: Stewart-DeHaan PJ, Creighton MO, Larsen LE, Jacobi JH, Sanwal M, Baskerville JC, Trevithick JR

Published in: Exp Eye Res 1985; 40 (1): 1-13

Download citation in RIS format

Aim of study (acc. to author)

Endpoint

morphol./histopathol. changes: morphological examination of the eye lens

Exposure

Exposure	Parameters
Exposure 1: 918 MHz Modulation type: pulsed Exposure duration: continuous for 6, 20, and 60 min	power: 24 kW peak value (transmitted power) SAR: 1,300 mW/g mean (65 W) SAR: 400 mW/g mean (20 W) SAR: 120 mW/g mean (6 W) SAR: 40 mW/g mean (2 W) SAR: 20 mW/g mean (1 W) SAR: 10 mW/g mean (0.5 W)

Exposure 1

Main characteristics

Frequency	918 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 6, 20, and 60 min

Modulation

Modulation type	pulsed
Pulse width	10 µs
Additional info	Repetition rates were varied to obtain various average powers. In some preliminary experiments, pulse durations of 20 µs were used.

Exposure setup

Exposure source	waveguide WR975
Setup	Lenses were maintained at constant temperature by circulating phosphate buffered saline (PBS) in a thermostatically-controlled exposure cell placed in a WR975 waveguide as previously described [Stewart-De Haan et al., 1983].
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	24 kW	peak value	-	-	transmitted power
SAR	1,300 mW/g	mean	measured	-	65 W
SAR	400 mW/g	mean	measured	-	20 W
SAR	120 mW/g	mean	measured	-	6 W
SAR	40 mW/g	mean	measured	-	2 W
SAR	20 mW/g	mean	measured	-	1 W
SAR	10 mW/g	mean	measured	-	0.5 W

Additional parameter details

Four reciprocal conditions were employed: 0.8, 2.4, 8, and 24 Wmin/g. In some preliminary experiments, a pulse peak power of 48 kW was used.

Measurement and calculation details

The SAR values were determined by measuring the temperature rise at the lens site of the exposure cell with the coolant flow off [Stewart-De Haan et al., 1983].

Reference articles

Stewart-DeHaan PJ et al. (1983): In vitro studies of microwave-induced cataract: separation of field and heating effects

Exposed system:

rat eye lens

Methods Endpoint/measurement parameters/methodology

Investigated system:

rat eye lens

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Different kinds of damage, such as subcapsular foam, holes in fibre cells and granulation of cell surface could be detected. A clear tendency of increasing depth of damage with increasing duration of exposure and dose rate could be observed. Lens fibre cell damage could be detected by scanning electron microscopy after 6 min irradiation at SAR values of 20 and 40 mW/g. After 1 h exposure at SAR values of 10 mW/g fibre cell damage could be detected by light microscopy.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

E.A. Baker Foundation of the Canadian National Institute for the Blind (CNIB), Canada

Medical Research Council (MRC; later on "Canadian Institutes of Health Research"), Canada

National Eye Institute (NEI; U.S. National Institutes of Health), Maryland, USA

U.S. Army Medical Research and Development Command of U.S. Medical Research and Materiel Command (USAMRMC)

Balci M et al. (2007): Effects of mobile phones on oxidant/antioxidant balance in cornea and lens of rats

Li HW et al. (2007): Proteomic analysis of human lens epithelial cells exposed to microwaves

Lixia S et al. (2006): Effects of 1.8 GHz radiofrequency field on DNA damage and expression of heat shock protein 70 in human lens epithelial cells

Ye J et al. (2002): Changes in gap junctional intercellular communication in rabbits lens epithelial cells induced by low power density microwave radiation

Creighton MO et al. (1987): In vitro studies of microwave-induced cataract. II. Comparison of damage observed for continuous wave and pulsed microwaves

Stewart-DeHaan PJ et al. (1983): In vitro studies of microwave-induced cataract: separation of field and heating effects