Testing the paint and testing a person
You usually cannot tell whether paint contains lead just by looking. The reliable ways to confirm lead are professional testing of the paint and a doctor's blood test to check a person's lead level.
For the home, a certified lead inspector or risk assessor can test painted surfaces and dust to identify lead and locate hazards. Some at-home test kits exist, but professional testing is more accurate and can pinpoint where the danger is. The building's age is a strong clue: pre-1978 housing is much more likely to contain lead paint.
For a person, especially a young child, a simple blood lead test ordered by a doctor shows whether lead has gotten into the body. This is important because children can be exposed without obvious symptoms.
You should not sand or scrape paint to "test" it yourself, since that can release lead dust. If you suspect lead paint and are unsure who should pay for testing or how to get your child checked, a free, confidential review can help you understand your options.
This is general information about California tenant rights, not legal advice. Every situation is different.