Cell phone use is associated with an inflammatory cytokine profile of parotid gland saliva
Siqueira EC, de Souza FT, Ferreira E, Souza RP, Macedo SC, Friedman E, Gomez MV, Gomes CC, Gomez RS. Cell phone use is associated with an inflammatory cytokine profile of parotid gland saliva.J Oral Pathol Med. 2016 Feb 14. doi: 10.1111/jop.12434. [Epub ahead of print]
BACKGROUND: There is controversy on the effects of the non-ionizing radiation emitted by cell phones on cellular processes and the impact of such radiation exposure on health. The purpose of this study was to investigate whether cell phone use alters cytokine expression in the saliva produced by the parotid glands.
METHODS: Cytokine expression profile was determined by enzyme linked immuno sorbent assay (ELISA) in the saliva produced by the parotid glands in healthy volunteers, and correlated with self-reported cell phone use and laterality.
RESULTS: The following parameters were determined, in 83 Brazilian individuals in saliva produced by the parotid glands comparing the saliva from the gland exposed to cell phone radiation (ipsilateral) to that from the contralateral parotid: salivary flow, total protein concentration, interleukin 1 β (IL-1 β), interleukin 6 (IL-6), interleukin 10 (IL-10), interferon γ (IFN-γ), and tumor necrosis factor α (TNF-α) salivary levels by ELISA. After multiple testing correction, decreased IL-10 and increased IL-1β salivary levels in the ipsilateral side compared with the contralateral side (P < 0.05) were detected. Subjects who used cell phones for more than 10 years presented higher differences between IL-10 levels in ipsilateral versus contralateral parotids (P = 0.0012). No difference was observed in any of the tested parameters in correlation with cell phone monthly usage in minutes.
CONCLUSION: The exposure of parotid glands to cell phones can alter salivary IL-10 and IL-1β levels, consistent with a pro-inflammatory microenvironment that may be related to heat production.
There are conflicting epidemiological data on the association between the cell phone use and the parotid tumorigenesis [7-10]. Notably, cell phone use was reportedly associated with increased salivary flow, total salivary protein concentration, blood flow rate, and volume of the exposed parotid glands [11, 12]. In a previous study, we could not show an association between cell phone use and alterations in salivary flow, total protein concentration, or salivary levels of p53 and p21 proteins, ROS, GSH, HSP70, HSP27, or IgA levels in the saliva . In this study, we tested the notion that in healthy individuals, cell phone exposure might affect the parotid gland salivary profile of inflammatory cytokines.
It is estimated that there are 7 billion cell phone users worldwide  and, in Brazil, there are 139 active cell phones per 100 inhabitants . The widespread use of cell phones and other non-ionizing radiation devices has raised legitimate concerns about their safety and possible effects on human health. The reported effects of cell phone use on parotid glands are inconsistent, with some studies suggesting an increased incidence of benign and malignant parotid tumors associated with the use of cell phones [7-10] and others failing to demonstrate such an association [8, 9]. A recent report from a panel of experts in the European Union states that on the basis of epidemiological studies, there is no overall evidence for an increased risk for brain tumors or tumors of the head and neck region associated with the non-ionizing radiation emitted from cell phones .
In the present study, self-reported cell phone use was seemingly associated with IL-1β and IL-10 cytokine level differences in the saliva produced by exposed vs the non-exposed parotid gland. Cell phone exposure was associated with an increased level of IL-1β (a pro-inflammatory cytokine) and decreased IL-10 level (anti-inflammatory cytokine) in the exposed parotid gland saliva . Notably, these differences in ipsi vs contralateral cytokine profile were more pronounced in long-term users (10 + years) than in those who used it less, a finding that may be interpreted to suggest a cumulative or chronic effect. This cumulative effect remains to be proven and should be viewed as preliminary observation only.
The inverse relationship of IL-1β and IL-10 has been previously reported to be correlated with weight in overweight Taiwanese adolescents . Interestingly, ionizing radiation can affect human health specifically tumor initiation and progression primarily by causing mutations, but may also exert deleterious effects by promoting inflammatory response to the initial radiation-induced injury . Such effect has never been shown or claimed for non-ionizing radiation. It is unclear if the observed differences in cytokine profiles described herein can somehow impact parotid tumorigenesis. To better address this issue, prospective cohort studies with long-term follow-up and targeting heavy users are needed.
The observed alterations in cytokine profile are in all likelihood attributed to heating effects of non-ionizing radiation. High temperature can alter the expression levels of cytokines (IL-12, TNF-α, and GM-CSF) and heat shock proteins in animals . In Humans, a high ambient heat can alter the IL-1 β and TNF-α levels in saliva . In addition, psycho-physical stress can also affect the expression of cytokines in saliva [26-28]. Additional limitations of our study include the young age of the participants, short overall usage of cell phone, lack of precise data, and the possible recall bias on actual usage.
In conclusion, the use of cell phone does not alter parotid salivary gland flow and the levels of IL-6 and TNF-α in the saliva produced by parotid glands. However, differences in salivary levels of IL-1β and IL-10 that mimic a pro-inflammatory profile in the parotids naturally exposed to cell phones, compared with the contralateral sides are noted. The causes of these differences and any possible biological significance and impact on human health remain to be defined and clarified.
Joel Moskowitz, Collaborative on Health and the Environment, Feb 16, 2016
Audio recording and slides can be downloaded from:
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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