Not as a casualty loss, but maybe a medical expense ? don't know, but maybe someone will jump in with an opinion

Anyone have any ideas on this?

"Lead-Based Paint Removal

You can include in medical expenses the cost of removing lead-based paints from surfaces in your home to prevent a child who has or had lead poisoning from eating the paint. These surfaces must be in poor repair (peeling or cracking) or within the child's reach. The cost of repainting the scraped area isn't a medical expense.

If, instead of removing the paint, you cover the area with wallboard or paneling, treat these items as capital expenses. See Capital Expenses, earlier. Don't include the cost of painting the wallboard as a medical expense."

From: https://www.irs.gov/publications/p502

"has or had" typically means, the child has been tested.