Google Glass ushers in a new trend in wireless devices. A wearable computer with head mounted display, Google Glass captures a lot of attention with its design, functions and life-style implication. Though it is not yet on sale, some people have raised concerns that Google Glass introduces new types of radiation exposure risks due to the way in which it is worn. This article explores the implications of on-body wireless devices on radiation exposure. Like all wireless devices, Google Glass emits electromagnetic radiation, called non-ionizing radiation, in the radio-frequency (RF) range in operation. The prototype Google Glass has Wi-Fi and Bluetooth antennas but no cellular antenna. Although there is still no consensus on whether this type of radiation is harmful to human body, growing scientific evidence shows correlation between wireless radiation and adverse health effects, including but not limited to brain tumors, impaired brain function, sperm damage and behavioral problems in children. In May 2011, the World Health Organization (WHO) classified radio-frequency electromagnetic radiation as “possibly carcinogenic to humans” based on increased risk of brain tumors.

Two Unique Risk Concerns

Google Glass represents a fundamentally new type of wireless device. Unlike, cell phones which are used next to the head only when making phone calls, Google Glass is designed to be worn on the user’s head in the same position all day long. The novel way in which Google Glass is used brings two unique risk concerns with regard to its radiation exposure. Firstly, scientific evidence indicates that cumulative exposure time plays a very important role in evaluating the health risks of wireless radiation. For example, the Interphone study one of the largest international study on cell phone use and brain tumors coordinated by the International Agency for Research on Cancer (IARC), shows no risk for general users (average 2 to 2.5 hours cell phone use a month) but a 40% increase in brain tumor glioma for “heavy” cell phone users - defined in the study as 1,640 hours or more cumulative cell phone use, or 30-minute daily use over a 10-year period of time (Interphone Report, 2010). A 2011 pooled analysis by Swedish researchers indicates a dose response that the risk of brain tumors (both glioma and astrocytoma) increased significantly for every 100 hr of cumulative exposure (Hardell et al, 2011). Other reported cumulative biological effects from exposure include effects on the Central Nervous System (CNS) and DNA damage (Lai, 1998). Google Glass is designed to be worn on the user’s head all day long. The potential cumulative exposure time from Glass is expected to be much longer than from cell phones and therefore the potential health risk for Glass could be much higher than cell phones. Secondly, scientific evidence indicates that the laterality of cell phone use - whether it is used primarily on one side of the head (ipsilateral use) or on both sides (contralateral use), also plays an important role in evaluating the risk of brain tumors. For example, the Interphone study shows that among heavy users (≥ 1,640 hr), ipsilateral users had a nearly doubled risk of glioma (compared to 40% increase for all) and tumors were more likely to occur on the side of the head most used for calling. The higher risk for ipsilateral exposure was also confirmed in other high-quality epidemiological studies (Hardell et al., 2006, 2009; Khurana et al., 2009). Since wireless energy absorption in brain tissue is non-uniform, “hotspots” are formed in certain area of the brain close to the transmitting antenna. It is the “hotspots” that are most problematic when it comes to the health risk of wireless radiation. Google Glass is designed to be worn in the same position all the time and the same part of the brain in close vicinity to Glass’s transmitting antenna will be subject to the highest localized exposure all the time. As a result, the long-term ipsilateral exposure could give Google Glass users a much higher risk of brain tumors and/or CNS impairment than mobile phone users.

Understanding SAR

The amount of RF radiation absorbed by a user's head and body is evaluated by its Specific Absorption Rate (SAR). SAR is defined as the power absorbed per mass of body tissue when exposed to wireless radiation. In the United States, the Federal Communication Commission (FCC) sets the SAR limit for public exposure to be 1.6 W/kg averaged over 1 gram of tissue. All wireless devices must be evaluated for their SAR values before going to market. According to the SAR Evaluation Report for Google Glass by UL CCS, the highest 1-g SAR in head for Glass is measured to be 1.110 W/kg, which comes from its Wi-Fi antenna. Since Google Glass has a SAR level below the safety limit of 1.6 W/kg, it is considered “safe” according to the FCC safety guideline. The current SAR standard of 1.6 W/kg was based on short-term or acute exposure (30 to 60 minutes of exposure) studies of animal behavioral disruption in the 1970s. There is scientific evidence showing that a longer exposure time at a lower level of RF radiation can also result in animal behavioral disruption and other biological effects (BioInitiative Working Group, 2007, 2012). However, long-term or chronic exposure to RF radiation has never been assessed in the current SAR standards. Therefore, one can reasonably argue that the current safety standards may not provide sufficient protection for Google Glass users.

How to Reduce Exposure?

Due to the unique way in which Google Glass is used, when it comes to reducing radiation exposure, most expert-recommended precautionary approaches for cell phone radiation won’t work for Glass. For example, the widely recommended “distance is your best friend” approach is not applicable for Glass - Glass users cannot hold Glass away from their heads, use a speakerphone or wear a headset; neither can they switch sides frequently or text. The good news is that alara case has a patented technology that is independently proven to reduce exposure to both cellular and Wi-Fi radiation from wireless devices while optimizing the devices’ performance. For example, when pairing with iPad Mini, alara’s technology can reduce Wi-Fi radiation exposure by 73%. alara's technology could be readily adapted for Google Glass to provide a precautionary solution for Glass users.