Official websites use .gov A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
[Atlanta, Ga.] : Centers for Disease Control and Prevention, National Center for Environmental Health, U.S. Dept. of Health and Human Services, Public Health Service, [1997]