Medical/biological study (experimental study)

Metamorphosis delay in Xenopus laevis (Daudin) tadpoles exposed to a 50 Hz weak magnetic field med./bio.

By: Severini M, Bosco L, Alilla R, Loy M, Bonori M, Giuliani L, Bedini A, Giliberti C, Palomba R, Pesolillo S, Giacomozzi E, Castellano AC

Published in: Int J Radiat Biol 2010; 86 (1): 37-46

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Aim of study (acc. to author)

The study was performed to prove that exposure to a relatively weak extremely low frequency magnetic field retards tadpoles development.

Background/further details

Two cohorts of 35 tadpoles were exposed during their immature period (whole larval stage) at two different magnetic flux densities and two comparable cohorts served as controls. The experiment was replicated three times (with litters from three different frog pairs).

Endpoint

tadpole development and teratogenic effects

Exposure

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: continuous for 60 days	magnetic flux density: 63.9 µT effective value (minimum value) magnetic flux density: 76.4 µT effective value (maximum value)

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	continuous for 60 days

Exposure setup

Exposure source	solenoid
Setup	1.6 m long solenoid with an internal diameter of 0.4 m, equipped with a wooden board along its axis without direct contact to the walls to support the glass aquariums; aquariums positioned symetrically to the solenoid's center

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	63.9 µT	effective value	measured	-	minimum value
magnetic flux density	76.4 µT	effective value	measured	-	maximum value

Exposed system:

animal
tadpoles of Xenopus laevis
whole body

Methods Endpoint/measurement parameters/methodology

tadpole development and teratogenic effects (degree of development, shape of hind and fore limbs, maturation frequencies, daily mean stages; daily stereoscopic microscopy)

Investigated system:

investigation on living organism

Time of investigation:

during exposure

Main outcome of study (acc. to author)

The data showed that long-term exposure (about 60 days) of cohort tadpoles to an extremely low frequency magnetic field of 50 Hz caused a significant reduction of tadpoles mean developmental rate of 0.05 stages/day during the whole larval stage, that brought about an increase of 2.5 days in mean maturation time of exposed tadpoles compared to controls. Maturation rates of exposed and control tadpoles changed during the course of the maturation period. Mortality, malformations or teratogenic effects were not observed in exposed matured tadpoles.
The authors conclude that a long-term exposure of Xenopus laevis tadpoles to a relatively weak 50 Hz magnetic field causes a sublethal effect that slows down their larval developmental rate and delays their metamorphosis.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro (ISPESL; National Institute for Occupational Safety and Prevention), Italy

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