You need to have the waste characterized by a laboratory. The Local Hazardous Waste Management Program in King County has a voucher incentive program to reimburse businesses for costs of testing and managing wastes. Most housing built before 1980 probably contains some lead-based paint.
Some paint also contains mercury.
To find out for sure, the paint must be tested. If you are remodeling or removing lead-based paint, you need to follow specific requirements to protect workers, tenants and the surrounding environment. By visiting this and other King County web pages, you expressly agree to be bound by terms and conditions of the site.