evidence: For context, there are both natural and human-made sources of EMF. Natural sources of EMF include lightning and ultraviolet radiation from the sun. Other human-made sources beyond Bluetooth technology include X-rays and microwave ovens. [...] This exposure limit is specified by the Specific Absorption Rate (SAR), which is measured by the rate at which RF energy is absorbed by the body. [...] "The absorption and distribution of electromagnetic energy in the body are very complex phenomena that depend on the mass, shape, and size of the body, the orientation of the body with respect to the field vectors, and the electrical properties of both the body and the environment. Other variables that may play a substantial role in possible biological effects are those that characterize the environment (e.g. ambient temperature, air velocity, relative humidity, and body insulation) and those that characterize the individual (e.g. age, gender, activity level, debilitation, or disease)."