Multiple people are concerned with Wi-Fi radiation, claiming that it interacts with body functions. The Universe is full of microwave radiation, but most of it is stopped by the atmosphere as some frequencies are completely blocked. Are there natural sources of microwave radiation inside the atmosphere? Yes, for instance microwave radiometers are used to catch this kind of radiation, produced by water vapor molecules, tuned at a specific frequency.
The most interesting part about infrared radiation is how any warm body produces it, this is the principle behind IR thermometers. You can prove that it's true pointing a hand-held device of this kind to sources with different temperature. The device works thanks to a sensor for IR radiation although the device doesn't work with a concrete panel placed before the source. Microwave radiation goes through that panel so there's an obvious difference between IR and microwave that doesn't come in terms of frequency. We should remind that infrared has more frequency than microwave, nearer from UV, gamma or X-rays in wavelength.
Let's say that a living organism in front of a heater is receiving a continuous amount of infrared radiation. If you achieve to modulate that radiation to a receiver, designed to interpret those intermittent chunks of heat, it's a completely safe method to transmit information. Or, in other words, no more dangerous than the temperature of any common body.