They are warning labels commonly found carton boxes. This image has a transparent background which can be used as an alpha channel.

If you are planning to create a carton box 3D model, you may want to consider Carton Box Cardboard Texture (Paper 0025) and Glossy Brown Duct Tape Texture (Others 0011).

It is the classic high voltage warning symbol in yellow and black contrast.

It is the chemical weapon warning symbol in yellow and black contrast.

It is the iconic radiation hazard warning symbol in yellow and black contrast.

It is the iconic biohazard warning symbol in yellow and black contrast.