Magnetic fields produced by power lines do not affect growth, serum melatonin, leukocytes and fledging success in wild kestrels

A blood-based multi-biomarker approach reveals different physiological responses of common kestrels to contrasting environments

The increase of urbanization and agricultural activities is causing a dramatic reduction of natural environments. As a consequence, animals need to physiologically adjust to these novel environments, in order to exploit them for foraging and breeding. The aim of this work was to compare the physiological status among nestling common kestrels (Falco tinnunculus) that were raised in nest-boxes located in more natural, rural, or urban areas in a landscape with a mosaic of land uses around Rome in Central Italy. A blood-based multi-biomarker approach was applied to evaluate physiological responses at multiple levels, including antioxidant concentrations, immunological functions, genotoxicity, and neurotoxicity. We found lower concentrations of glutathione and GSH:GSSG ratio values and higher proportions of monocytes in urban birds compared to the other areas. We also found higher DNA damage in rural compared to urban and natural krestels and inhibition of butyrylcholinesterase activity in urban and natural birds compared to rural area. Finally, we found similar values among study areas for respiratory burst, complement system, bactericidal capacity, and plasma non-enzymatic antioxidant capacity. These results suggest that (i) city life does not necessarily cause physiological alterations in kestrels compared to life in other habitats, and (ii) environmental pressures are likely to differ in typology and intensity across habitats requiring specific responses that a multi-biomarker approach can help to detect. Further studies are needed to assess which factors are responsible for the physiological differences among city, rural, and natural birds, and whether these differences are consistent across time and space.

Bird electrocution on power lines: Spatial gaps and identification of driving factors at global scales

Universal energy access is one of the targets of the Sustainable Development Goals (SDGs), and thus the deployment of electricity grids is expected to expand globally in the coming decades. However, the installation of power lines is not biodiversity-friendly. In particular, electrocution on power pylons is a major cause of bird mortality worldwide, including for some severely endangered species. Over the last decades, different studies have improved our understanding of the factors influencing the risk of electrocution in birds, but until now spatial gaps in our knowledge of these impacts and the factors driving global patterns of bird electrocution have not been assessed. In this study, we evaluated data from a total of 114 studies that provided information on bird mortality rates on power lines, and we analyzed the factors driving electrocution rates for all bird species, and then for all raptors and large eagles separately. Our results showed a high spatial distribution bias, as more than 80% of the studies were carried out in developed countries, mostly in Europe and North America. By contrast, no systematic studies have been found for Oceania and very few for South America and Africa. Europe showed the highest electrocution rates for birds, South America for raptor species and Africa for eagles. Socio-economic factors best-explained bird and raptor electrocution rates, while climate-related factors were the most influential for eagles. Contrary to our expectations, factors related to pylon design were the least influential on overall electrocution rates. Variables related to study design showed highly variable levels of influence. This could be due to the lack of standardized protocols. Although bird electrocution has been extensively studied, there are large areas where no studies have been carried out or for which data are inaccessible. This could be because in these areas the power distribution network is still sparse, or that most studies are not public or accessible to the international community. Researchers and managers should promote the publication of studies, as awareness is the first step to solving these problems. The factors identified could be applied globally to the design and planning of power grids and the identification of mortality hotspots. This would help mitigate the creation of new mortality hotspots, especially in developing countries where the installation of new power lines has been growing exponentially in recent years.

Melatonin: a Potential Shield against Electromagnetic Waves

Melatonin, a vital hormone synthesized by the pineal gland, has been implicated in various physiological functions and in circadian rhythm regulation. Its role in the protection against the non-ionizing electromagnetic field (EMF), known to disrupt the body's oxidative/anti-oxidative balance, has been called into question due to inconsistent results observed across studies. This review provides the current state of knowledge on the interwoven relationship between melatonin, EMF, and oxidative stress. Based on synthesized evidence, we present a model that best describes the mechanisms underlying the protective effects of melatonin against RF/ELF-EMF induced oxidative stress. We show that the free radical scavenger activity of melatonin is enabled through reduction of the radical pair singlet-triplet conversion rate and the concentration of the triplet products. Moreover, this review aims to highlight the potential therapeutic benefits of melatonin against the detrimental effects of EMF, in general, and electromagnetic hypersensitivity (EHS), in particular.

The effects of extremely low-frequency magnetic fields on melatonin and cortisol, two marker rhythms of the circadian system

In the past 30 years the concern that daily exposure to extremely low-frequency magnetic fields (ELF-EMF) (1 to 300 Hz) might be harmful to human health (cancer, neurobehavioral disturbances, etc) has been the object of debate, and has become a public health concern. This has resulted in the classification of ELF-EMF into category 2B, ie, agents that are “possibly carcinogenic to humans” by the International Agency for Research on Cancer. Since melatonin, a neurohormone secreted by the pineal gland, has been shown to possess oncostatic properties, a “melatonin hypothesis” has been raised, stating that exposure to EMF might decrease melatonin production and therefore might promote the development of breast cancer in humans. Data from the literature reviewed here are contradictory. In addition, we have demonstrated a lack of effect of ELF-EMF on melatonin secretion in humans exposed to EMF (up to 20 years' exposure) which rebuts the melatonin hypothesis. Currently, the debate concerns the effects of ELF-EMF on the risk of childhood leukemia in children chronically exposed to more than 0.4 μT. Further research is thus needed to obtain more definite answers regarding the potential deleterious effects of ELF-EMF.

Effects of whole-body exposure to 915 MHz RFID on secretory functions of the thyroid system in rats

As a part of an investigation on the potential risks of radiofrequency identification (RFID) on human health, we studied whether exposure to 915 MHz RFID in rats significantly affected the secretory function of the thyroid system. A reverberation chamber was used as a whole-body exposure system. Male Sprague-Dawley rats were exposed for 8 h per day, 5 days per week, for a duration of 2, 4, 8, or 16 weeks. The estimated whole-body average specific absorption rate (SAR) varied from 3.2 to 4.6 W/kg depending on the age/mass of the animals for the field of the 915 MHz RFID reader. Plasma levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were evaluated via enzyme-linked immunosorbent assay. Morphological changes in the thyroid gland were then analyzed. No changes in T3, T4, or TSH were observed over time between the sham- and RFID-exposed groups. We suggest that subchronic exposure to 915 MHz RFID at a SAR of 4 W/kg does not cause significant effects on thyroid secretory function.