It's still a doctoral level degree, so they would technically be referred to as "doctor".

Is a DrPH a Doctor?

A Doctor of Public Health (abbr. DrPH, Dr.PH. or D.P.H.; Latin doctor publica sanitas) is a doctoral degree awarded in the field of Public Health. DrPH is an advanced and terminal degree that prepares its recipients for a career in advancing public health practice, leadership, research, teaching, or administration.

Who can legally be called a Doctor?

Traditionally, the title doctor was reserved for medical doctors, or scholars who'd completed postgraduate training to a doctoral level, and were recognised by their peers as an expert in their field. Indeed, a number of dictionary definitions appear to support these two categories.