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The widespread use of mobile phones has led to public concerns about the health effects associated with exposure to radiofrequency (RF) fields. The paramount concern of most persons relates to the potential of these fields to cause cancer. Unlike ionizing radiation, RF fields used for mobile telecommunications (800-1900 MHz) do not possess sufficient energy to directly damage DNA. Most rodent bioassay and in vitro genotoxicity/mutation studies have reported that RF fields at non-thermal levels have no direct mutagenic, genotoxic or carcinogenic effects. However, some evidence has suggested that RF fields may cause detectable postexposure changes in gene expression. Therefore, the purpose of this study was to assess the ability of exposure to a 1.9 GHz pulse-modulated RF field for 4 h at specific absorption rates (SARs) of 0.1, 1.0 and 10.0 W/kg to affect global gene expression in U87MG glioblastoma cells. We found no evidence that non-thermal RF fields can affect gene expression in cultured U87MG cells relative to the nonirradiated control groups, whereas exposure to heat shock at 43 degrees C for 1 h up-regulated a number of typical stress-responsive genes in the positive control group. Future studies will assess the effect of RF fields on other cell lines and on gene expression in the mouse brain after in vivo exposure.

While the prevalence of tobacco use has decreased in Canada over the past decade, that of marijuana use has increased, particularly among youth. However, the risks of adverse health effects from marijuana smoke exposure, specifically as compared to tobacco, are currently not well understood. The objectives of this study were to evaluate the relative ability of matched marijuana and tobacco condensates to induce (geno)toxic responses in three in vitro test systems. This study provides comparative data for matched sidestream and mainstream condensates, as well as condensates prepared under both a standard and an extreme smoking regime designed to mimic marijuana smoking habits. The results indicate that tobacco and marijuana smoke differ substantially in terms of their cytotoxicity, Salmonella mutagenicity, and ability to induce chromosomal damage (i.e., micronucleus formation). Specifically, the marijuana condensates were all found to be more cytotoxic and more mutagenic in the presence of S9 than the matched tobacco condensates. In contrast, the tobacco condensates appeared to induce cytogenetic damage in a concentration-dependent manner, whereas the matched marijuana condensates did not. In addition, when corrected for total particulate matter yield, little difference was observed in the mutagenic activity of samples smoked under the extreme vs the standard regime for both tobacco and marijuana condensates.

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