The answer is yes, but with caveats. That's because it isn't clear exactly what your area of specialty is, and what types of positions you're looking for. For example, as you may know there are some positions named "Public Health Chemist", while others are chemist positions in public health labs, like "Environmental Health Specialist". In many cases the Chem. degree is key, and then they will talk about relevant experience. A MPH is one way to illustrate that you have that experience, but other transferable skills can also fit the bill.
That said, Three things might help:
1: Chemistry.org has fantastic resources, including an article entitled: "Chemists Needed at Public Health Laboratories" at http://www.chemistry.org/portal/a/c/s/1/feature_pro.html?id=fda98eae97ec11d6f0a64fd8fe800100
2:Association of Public Health Laboratories at http://www.aphl.org/ has links (which have employment links) to all of their labs at http://www.cen-chemjobs.org/profiles/aphlprofile.html
3: http://cen-chemjobs.org/ actually lists positions at the APHL labs.
Bill L. & Naledi S.