Who covers testing and remediation
When there is reason to believe deteriorating lead paint is creating a hazard in the rental, addressing that hazard — including testing, safe repair, and cleanup — often falls to the landlord as part of keeping the home habitable, especially where children live.
If you report peeling paint or a suspected lead hazard, and the landlord has a duty to keep the unit safe, the landlord is generally the party expected to investigate and handle any needed testing and safe remediation. Tenants usually should not pay out of pocket to fix a hazard that is the landlord's responsibility, and they should not attempt lead cleanup themselves.
Because the rules can vary, it helps to document your concern in writing and ask the landlord to test and safely address the paint. Keep a copy of that request. Local health departments and lead-poisoning-prevention programs can also be resources.
If your landlord refuses to test or fix a lead hazard they are responsible for, you have options. A free, confidential review can explain who is responsible and how to push for a safe resolution.
This is general information about California tenant rights, not legal advice. Every situation is different.