While ATSDR has made this e-manual publicly available for transparency in our process, some of the resources referenced might not be publicly available due to agency policy. ATSDR also recognizes that because scientific guidance is constantly evolving, some of these resources could change or become outdated. ATSDR has made a diligent effort to ensure the accuracy and the currency of the presented information.

Any photos without attribution are either those of ATSDR staff or stock photos that ATSDR purchased for use. Any mention of trade names or commercial products is for identification only and does not constitute endorsement or recommendation by ATSDR, the Public Health Service, or the U.S. Department of Health and Human Services.

Page last reviewed: April 14, 2022