Can these readily recognisable and familiar images be used in your document?
Have you considered what the International Symbols have available?
There is a small set of commonly used International Symbols available for free download at http://www.aiga.org/symbol-signs/
Your document is about road safety, cars or pedestrians. Would familiar road signs assist understanding?
Your document is on workplace safety. What are the signs used for danger in the workplace? Is this the right image for the context of your document?
Are their common images used in your workplace for safety gear - goggles, safety shoes and hard hats? Ask for permission to use these images.
Email Cathy at email@example.com for further ideas or help with your documents