REDUCED LITTER SIZES FOLLOWING 48-H OF PRENATAL EXPOSURE TO 5 nT TO 10 nT,0.5 HZ MAGNETIC FIELDS: IMPLICATIONS FOR SUDDEN INFANT DEATHS

Extremely low frequency electromagnetic fields exposure during the prenatal and postnatal periods alters pro-inflammatory cytokines levels by gender

Maternal exposure to the excessive electromagnetic fields is considered harmful to infants and associated with several health problems in life, such as neurological or immune diseases. In this present study we aimed to investigate the potential effects of extremely low-frequency electromagnetic field (ELF-EMF) exposure during the gestational and lactational period of dams on immune system parameters. The development of white blood cells (WBC), lymphocyte subpopulations (CD4⁺ T cells, CD8⁺ T cells, Natural Killer (NK) cells, and B cells) and production of T cell related cytokines were explored in the offsprings. Significant changes were found in WBC and lymphocyte counts. Although no changes in lymphocyte subunits were observed among groups, CD4⁺ cells were significantly increased in the female group exposed to ELF-EMF. Also, IL-17A and IFN-γ levels increased in plasma and spleen. The mean IL-4 level and the expression level of the IL-4 gene were not changed, in the experimental groups. But the expression of the IL-17A gene was also upregulated, which supports cytokine quantification analyses. In conclusion, ELF-EMF exposure in the prenatal and postnatal period increases the level of IL-17A in the spleen and blood of young female rats, and it upregulates IL-17 gene expression in the spleen, resulting in CD4⁺ cell proliferation and inflammation.

Extremely-low frequency magnetic field exposure for simulating geomagnetic pulsations in Alexandrium pacificum and Gymnodinium catenatum cultures

Growth and chain formation in cultures of the chain-forming dinoflagellates Alexandrium pacificum and Gymnodinium catenatum were previously found to be susceptible to space weather variables. A clock drive was used to deliver a frequency of 0.5 Hz and central amplitude of 7 µT in order to perform in vitro simulation of geomagnetic pulsations (composed of extremely low-frequency magnetic fields, ELFMF) which occur during high geomagnetic activity (GMA) periods. Short-term exposure (hours) to this ELFMF increased relative cell growth around 10 nT of naturally occurring GMA. Relative growth outside these intervals gradually approached 0% or was negative for G. catenatum. Differential survival to a subsequent shock was inversely related to growth, and minimal survival coincided with the same 10 nT interval. Relative growth and survival displayed opposite hormetic curves towards GMA: inverted U-shaped for growth, and J-shaped for survival. After exposure to this ELFMF, positive phototaxis response was not lost, but the percentage of cells swimming was slightly reduced. Long-term exposure (days) increased relative growth in A. pacificum but reduced in G. catenatum when low GMA was taking place. These alterations in growth were both associated with a reduction in the cellular pool of mycosporine-like amino acids (MAAs). MAAs that are more susceptible to oxidation were more reduced than those resistant, highlighting that an ELFMF can act by increasing cellular oxidative stress status. The higher susceptibility of G. catenatum found is in compliance with the previous association of its natural populations at the western Iberia coast with periods of solar activity minima and GMA minima.

Altered neuronal densities in sexually dimorphic structures: comparable effects from perinatal magnetic fields with nitric oxide synthase inhibitors and postnatal hypoxia

Cytometry of the neuronal density within four sexually dimorphic nuclei was completed for adult rats that had been perinatally exposed to 0.5Hz, 5-10nT magnetic fields or sham conditions while their mothers drank tap water containing the nitric oxide synthase (NOS) inhibitor L-NAME or only tap water. One week after birth the rats were rendered hypoxic for 1 min or served as controls. Exposures to either the magnetic field or the NOS inhibitor reduced the numbers of neurons within the bed nucleus of the stria terminalis by about 25%, whereas exposure to either the hypoxia or magnetic fields resulted in comparable decreases in cell numbers within the ventromedial nucleus (dorsomedial part). For comparison males had 15% fewer neurons in these nuclei compared to females. The effect sizes for the interactions involving the perinatal exposure for 8 days to the magnetic fields were comparable to the magnitudes of those associated with 1 min of hypoxia 1 week postnatally. These results show the sensitivity of specific structures of the developing brain to interactions between subtle environmental variables.