An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Groffman PM, Williams CO, Pouyat RV, Band LE, Yesilonis ID.Groffman PM, et al.J Environ Qual. 2009 Jul 23;38(5):1848-60. doi: 10.2134/jeq2008.0521. Print 2009 Sep-Oct.J Environ Qual. 2009.PMID: 19643750
Wexler SK, Goodale CL, McGuire KJ, Bailey SW, Groffman PM.Wexler SK, et al. Among authors: groffman pm.Proc Natl Acad Sci U S A. 2014 Nov 18;111(46):16413-8. doi: 10.1073/pnas.1404321111. Epub 2014 Nov 3.Proc Natl Acad Sci U S A. 2014.PMID: 25368188Free PMC article.