Medical/biological study (experimental study)

Delayed maturation of Xenopus laevis (Daudin) tadpoles exposed to a weak ELF-MF: sensitivity to small variations of magnetic flux density med./bio.

By: Severini M, Bosco L

Published in: Giuliani L, Soffritti M: Non-thermal effects and mechanisms of interaction between electromagnetic fields and living matter. Mattioli 1885, 2010: 247-260; ISBN 978-88-6261-166-4

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Aim of study (acc. to author)

The data of a previous experiment (Severini et al. 2010) are re-processed to evaluate the sensitivity of tadpole developmental rate to small variations of weak extremely low frequency magnetic flux densities (in two different aquariums E1 and E2).

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 22 days	magnetic flux density: 70.1 µT mean (+/- 0.3 µT in the center of E1) magnetic flux density: 72.4 µT mean (+/- 0.4 µT in the center of E2) magnetic flux density: 63.9 µT minimum (E1) magnetic flux density: 76.4 µT maximum (E1) magnetic flux density: 68.4 µT minimum (E2) magnetic flux density: 76.4 µT maximum (E2)

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Exposure duration	continuous for 22 days

Exposure setup

Exposure source	solenoid
Setup	1.6 m long solenoid with a diameter of 0.4 m; aquariums E1 and E2 placed on a wooden board in the center of the solenoid
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	70.1 µT	mean	calculated	-	+/- 0.3 µT in the center of E1
magnetic flux density	72.4 µT	mean	calculated	-	+/- 0.4 µT in the center of E2
magnetic flux density	63.9 µT	minimum	measured	-	E1
magnetic flux density	76.4 µT	maximum	measured	-	E1
magnetic flux density	68.4 µT	minimum	measured	-	E2
magnetic flux density	76.4 µT	maximum	measured	-	E2

Exposed system:

animal
spawn and 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, daily maturation frequencies, daily mean stages; daily stereoscopic microscopy from day 9)

Investigated system:

investigation on living organism

Time of investigation:

during exposure

Main outcome of study (acc. to author)

The data showed that tadpoles of aquarium E2 under the stronger field matured with a significant delay of 2.5 days with respect to tadpoles of aquarium E1 under the weaker field. This delay was clearly caused by exposures to two slightly different ranges of magnetic flux densities. The results suggest the existence of a field threshold around 70 µT in controlling the animal's developmental rate.

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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