http://agr.wa.gov/ This site is the database maintained by the Washington State Department of Agriculture which provides results from the comparison of each individual fertilizer product to the Washington Standards for metals in fertilizers.

http://www.atsdr.cdc.gov/toxfaq.html Maintained by the Agency for Toxic Substances and Disease Registry (ATSDR), this web site provides answers to frequently asked questions about a wide range of toxic substances including the metals most often found in fertilizers. The ATSDR is an agency of the U.S. Department of Health and Human Services that provides a wealth of information on human health effects from exposure to hazardous substances.

http://www.scorecard.org/chemical-profiles/  This web is maintained by the Environmental Defense Fund and it Provides detailed information on more than 6,800 chemicals.

http://toxnet.nlm.nih.gov/ The National Library of Medicine provides free access to the TOXNET system of databases on toxicology, hazardous substances, and related areas of interest.