This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+2623 forms with similar adjacent characters prevents a line break inside it.
The CLDR project calls this character “biohazard” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: sign.
This character is designated as an emoji. It will be rendered as monochrome character on conforming platforms. To enable colorful emoji display, you can combine it with Variation Selector-16: ☣️ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
Hazard symbols or warning symbols are recognisable symbols designed to warn about hazardous or dangerous materials, locations, or objects, including electromagnetic fields, electric currents; harsh, toxic or unstable chemicals (acids, poisons, explosives); and radioactivity. The use of hazard symbols is often regulated by law and directed by standards organizations. Hazard symbols may appear with different colors, backgrounds, borders, and supplemental information in order to specify the type of hazard and the level of threat (for example, toxicity classes). Warning symbols are used in many places in place of or in addition to written warnings as they are quickly recognized (faster than reading a written warning) and more universally understood, as the same symbol can be recognized as having the same meaning to speakers of different languages.
Navigational hazards are generally marked on nautical charts, and are also often marked by moored buoys, and changes are published in notices to mariners.