Ключевые слова: area, background, beware, biology, button, caution, chemical, chemistry, danger, dead, dirty, environment, explosive, gamma, garbage, graphic, green, grunge, hydrogen, icon, infectious, ink, irritation, isotope, landmark, nuclear, power, radiation, radio, radioactive, ray, risk, safety, sign, solar, splash, station, substance, symbol, toxic, uranium, wallpaper, warning, worn,