Effects of 700 and 3500 MHz 5G radiofrequency exposure on developing zebrafish embryos.

Telecommunications industries are rapidly deploying the fifth generation (5G) spectrum and there is public concern about the safety and health impacts of this type of Radio Frequency Radiation (RFR), in part because of the lack of comparable scientific evidence. In this study we have used a validated commercially available setting producing a uniform field to expose zebrafish embryos (ZFe) to unmodulated 700 and 3500 MHz frequencies. We have combined a battery of toxicity, developmental and behavioral assays to further explore potential RFR effects. Our neurobehavioral profiles include a tail coiling assay, a light/dark activity assay, two thigmotaxis anxiety assays (auditory and visual stimuli), and a startle response - habituation assay in response to auditory stimuli. ZFe were exposed for 1 and 4 h during the blastula period of development and endpoints evaluated up to 120 hours post fertilization (hpf). Our results show no effects on mortality, hatching or body length. However, we have demonstrated specific organ morphological effects, and behavioral effects in activity, anxiety-like behavior, and habituation that lasted in larvae exposed during the early embryonic period. A decrease in acetylcholinesterase activity was also observed and could explain some of the observed behavioral alterations. Interestingly, effects were more pronounced in ZFe exposed to the 700 MHz frequency, and especially for the 4 h exposure period. In addition, we have demonstrated that our exposure setup is robust, flexible with regard to frequency and power testing, and highly comparable. Future work will include exposure of ZFe to 5G modulated signals for different time periods to better understand the potential health effects of novel 5G RFR.

Molecular effects of polystyrene nanoplastics toxicity in zebrafish embryos (Daniorerio).

Plastics pose a health hazard to living beings and the environment. Plastic degradation produces nano-sized plastic particles (NPs) that end up in terrestrial and aquatic ecosystems, including oceans, rivers, and lakes. Their presence in air, drinking water, sediments, food, and personal care products leads to a variety of exposure routes for living beings, including humans. The toxicity mechanisms of these nanomaterials (NMs) in living organisms and ecosystems are currently unknown, making it a priority to understand their effects at the molecular and cellular levels. The zebrafish (Zf) (Danio rerio) is a model organism which has a high homology with humans and has been widely used to assess the hazard of different xenobiotics. In this study, the expression changes of different genes in 120 hpf Zf embryos (Zfe) after exposure to polystyrene (PS) NPs (30 nm) at concentrations of 0.1, 0.5 and 3 ppm were investigated. The results showed that the gene encoding heat shock protein (hsp70) was down-regulated in a dose-dependent manner. The genes encoding superoxide dismutase (SOD 1 and SOD 2), apoptotic genes (cas 1 and cas 8) and interleukin 1-ß (il1ß) were activated at the concentration of 3 ppm PS NP, while the anti-apoptotic gene Bcl2α was inhibited at 0.5 and 3 ppm. In addition, the neurotransmitter-related gene Acetyl-Cholinesterase (ache) was significantly inhibited and the DNA repair genes (gadd45α and rad51) were also down-regulated. In contrast, the mitochondrial metabolism-related gene cox1 did not alter its expression in any of the treatments. Most of the changes in gene expression occurred at the highest concentration of NPs. Overall, the results indicated that NPs generated cellular stress that caused certain alterations in normal gene expression (oxidative stress, apoptotic and inflammatory processes, neurotoxicity and anti-apoptotic proteins), but did not cause any mortality after 120 hpf exposure at the three concentrations assayed. These results highlight the need for further studies investigating the effects, at the molecular level, of these materials in humans and other living organisms.

Human biomonitoring in health risk assessment in Europe: Current practices and recommendations for the future.

Human biomonitoring (HBM) is an important tool to survey the internal exposure of humans which represents the real life chemical body burden to chemicals and/or their metabolites. It results from total exposure to chemical substances from different sources and via different routes. These substances may be regulated under different legislative frameworks on chemicals (e.g., environmental, occupational, food safety etc). In occupational health, HBM has long traditions to control the exposures at workplaces. By providing accurate data on internal exposure, HBM data can improve human health risk assessment (RA) for both the general population and workers. Although the past few years have shown good examples on the use of HBM in the RA of chemicals, there is still quite some work to be done to improve its use in a regulatory RA. Under the scope of the European Human Biomonitoring Initiative (project HBM4EU, 2017-2021), the current study reviews the state-of-the-art of HBM use in chemicals RA with a special focus in Europe, and attempts to identify hurdles and challenges faced by regulators. To gather information on the use of HBM, including the availability of guidance on how to use it in RA, the RA schemes applied by different European or international organizations were analysed. Examples of such use were identified for a few selected groups of chemicals of concern for human health. In addition, we present the results of a survey, aimed at collecting information from national regulatory risk assessors on their day-to-day RA practices, the use of HBM data, and the obstacles and challenges related to their use. The results evidenced and explained some of the current obstacles of using HBM data in RA. These included the lack of HBM guidance values or biomonitoring equivalents (BEs), limited toxicokinetic information to support the interpretation of HBM data and, in the occupational health and safety (OSH) field, the lack of legal enforcement. Therefore, to support the integration of HBM in regulatory RA, we recommend, on one hand, the elaboration of a EU level guidance on the use of HBM in RA and, on the other hand, the continuation of research efforts to integrate HBM with new RA approaches using in vitro/in silico data and Adverse Outcome Pathways (AOPs).