What is different between normal dust and lead contaminated dust?

Regular indoor dust tends to contain a mix of sloughed-off skin cells, hair, clothing fibers, bacteria, dust mites, bits of dead bugs, soil particles, pollen, and microscopic specks of plastic.  Lead-contaminated dust is defined as “surface dust in residential dwellings” that contains lead in excess of levels determined “to pose a threat of adverse health effects…” As defined in TSCA section 401 (15 U.S.C. 2681(9)). Lead contaminated dust presents a health hazard whereas normal dust does not.