Rapporteur report: implications for exposure guidelines

There is a paucity of information regarding the long-term health effects associated with exposure to static magnetic fields. Perceptual and other acute effects have been demonstrated above a threshold of about 2 T, and these form the basis for human exposure standards at present. Exposures well above this threshold are increasingly becoming more common as the technology associated with magnetic resonance imaging advances. Therefore, priority should be given to assessing the health risks associated with exposures to such fields. Studies should include a prospective cohort study investigating cancer risks of workers and patients exposed to fields in excess of 2 T, a study investigating effects on human cognitive performance from repeated exposures, and a molecular biology study investigating acute changes in genomic responses in volunteers exposed to fields of up to 8 T. Studies investigating the effects of long-term exposure on cancer, and on neurobehavioural development are also recommended using animals, where the use of transgenic models is encouraged. In addition, dosimetric studies should be conducted using high-resolution male, female and pregnant voxel phantoms, as should theoretical studies investigating the local currents induced in the eye and in the heart by movement during exposure. Finally, studies are recommended to investigate further the ability of static magnetic fields to significantly affect radical pair reactions in biological systems.     

Single, brief exposure to a 50 Hz magnetic field does not affect the performance of an object recognition task in adult mice

A number of studies have shown that power frequency magnetic fields may affect spatial memory functions in rodents. An experiment was performed using a spontaneous object recognition task to investigate if nonspatial working memory was similarly affected. Memory changes in adult, male C57BL/6J mice were assessed by measuring the relative time within which the animals explored familiar or novel stimulus objects. Between initial testing and retesting, the animals were exposed for 45 min to a 50 Hz magnetic field at either 7.5 microT, 75 microT or 0.75 mT. Other animals were sham-exposed with ambient fields of less than 50 nT. No significant field-dependent effects on the performance of the task were observed at any flux density (for all measures, P > 0.05). These data provide no evidence to suggest that nonspatial working memory was affected in mice by acute exposure to an intense 50 Hz magnetic field.     

Frequency of ace, epa and elrA Genes in Clinical and Environmental Strains of Enterococcus faecalis

Surface proteins play an important role in the pathogenesis of enterococcal infections. Some of them are candidates for a vaccine, e.g., the frequency of endocarditis in rats vaccinated with Ace protein was 75 % as 12 opposed to 100 % in those who weren’t. However, there are other components of enterococcal cells, such as Epa antigens or internalin-like proteins, which may be used in the prophylaxis of infections caused by them. However, also other virulence factors and resistance to antibiotics are important during enterococcal infection. Therefore, the relevance of ace, epa, elrA, other virulence genes, as well as resistance to antibiotics was investigated. 161 Enterococcus faecalis strains isolated from teaching hospitals in Lodz, cultured according to standard microbiological methods, were investigated for the presence of genes encoding surface proteins by PCR. Results were analyzed with χ² test. The elrA gene was found in all clinical and environmental strains, the ace gene was also widespread among E. faecalis (96.9 %). Both tested epa genes were found in the majority of isolates (83.25 %). There was correlation between the presence of esp and ace genes (p = 0.046) as well as between epa and agg genes (p = 0.0094; χ² test). The presence of the genes encoding surface proteins investigated in our study in the great majority of isolates implies that they would appear to be required during E. faecalis infection. Therefore, they could be excellent targets in therapy of enterococcal infections or, as some studies show, candidates for vaccines.     

Systematic review of wireless phone use and brain cancer and other head tumors

We conducted a systematic review of scientific studies to evaluate whether the use of wireless phones is linked to an increased incidence of the brain cancer glioma or other tumors of the head (meningioma, acoustic neuroma, and parotid gland), originating in the areas of the head that most absorb radiofrequency (RF) energy from wireless phones. Epidemiology and in vivo studies were evaluated according to an agreed protocol; quality criteria were used to evaluate the studies for narrative synthesis but not for meta-analyses or pooling of results. The epidemiology study results were heterogeneous, with sparse data on long-term use (≥ 10 years). Meta-analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head. Assessment of the review results using the Hill criteria did not support a causal relationship between wireless phone use and the incidence of adult cancers in the areas of the head that most absorb RF energy from the use of wireless phones. There are insufficient data to make any determinations about longer-term use (≥ 10 years).     

Preliminary evaluation of selected inflammatory cytokine gene expression in lymphocytes isolated from whole human blood infected with trans-anethole-treated Staphylococcus aureus Newman strain

In our previous study based on a whole-blood model of sepsis infected with trans-anethole (TA)-treated Staphylococcus aureus, we have found that innate immune response was more effective in comparison to non-treated cells. Due to the previous observation, in the current preliminary study, a primary adaptive immune response was analysed. This study was conducted to evaluate the expression of selected cytokine (IL1B, IL2, IL6, IL10, TNF, TGFB1, IFNG) and Toll-like receptor (TLR2) genes in lymphocytes isolated from whole human blood infected with S. aureus Newman strain treated with TA. The lymphocytes were isolated by density gradient centrifugation from blood samples infected with S. aureus, as well as from non-infected samples. Gene expression was measured using quantitative real-time PCR. The lymphocytes isolated from the blood infected with TA-treated staphylococcal cells demonstrated significantly greater IL10, IL1B, IL6, TNF and TLR2 expression. Hence, it is possible that the previously observed changes in the surface structure of TA-treated S. aureus Newman strain may significantly increase the relative expression of IL10, IL1B, IL6, TNF and TLR2 genes in lymphocytes; however, further studies are needed.