In "Would Contact with Extraterrestrials Benefit or Harm Humanity?", in Acta Astronautica, researchers from NASA and the University of Pennsylvania's Departments of Geography and Meteorology systematically analyze a broad range of contact scenarios, categorizing each one as beneficial, neutral, or harmful to humanity. Although the researchers do not perform quantitative analysis on the likelihood of the various scenarios, they do note that a relatively large number fall into the "harmful" category. Because of this, they recommend that Earth's messages to extraterrestrials be written more cautiously.
NASA routinely beams messages into the universe in an attempt to contact extraterrestrial intelligence. In more than 50 years of listening for a response, they've heard zilch. Which might be good. For even as NASA sends messages, some of its scientists wonder what it is they should say, and whether Earth should, indeed, keep putting out the proverbial welcome mat.