Full Text
The Full Text of this article is available as a PDF (1.9 MB).
. 2002 Apr;110(4):A196–A199. doi: 10.1289/ehp.110-a196
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.