1 Environmental Defense Fund (EDF), 1999, Chemical Profile: "Hydrofluoric Acid" (New York: EDF; see webpage: http:/www.scorecard.org/chemical-profiles/); Environmental Health Center (EHC is a division of the National Safety Council), 1997, "Environment Writer: Hydrogen Fluoride (Hydrofluoric Acid) (HF) Chemical Backgrounder" (Washington, D.C.: EHC; see webpage: http://www.nsc.org/ehc/ew/chems/hydrfluo.htm); Richard J. Lewis, Sr. (ed.), 1993, Hazardous Chemicals Desk Reference (New York: Van Nostrand Reinhold); New Jersey Department of Health and Senior Services, 1998, "Hazardous Substance Fact Sheet: Hydrogen Fluoride" (Trenton, New Jersey; see webpage: http://www.state.nj.us/health/eoh/rtkweb/rtkhsfs.htm); and U.S. EPA, Office of Air Quality Planning and Standards, 1998, "Hydrogen Fluoride (and Related Compounds)" (Washington, D.C.: U.S. EPA; see webpage: http://www.epa.gov/ttn/uatw/hlthef/hydrogen.html); Gosselin RE, Smith RP, Hodge HC, 1984, "Clinical Toxicology of Commercial Products," 5th edition, (Baltimore, MD: Williams & Wilkins).

2 The national chemical use data are from Stanford Research Institute (SRI) International, 1995, Chemical Economics Handbook, "Fluorine Compounds" (Palo Alto, California: SRI). The Massachusetts chemical use data are from the Massachusetts Department of Environmental Protection (MA DEP), 1998, "Massachusetts Toxics Use Reduction Act Chemical Reporting Data" (Boston: MA DEP).

3 SRI, 1995 (see endnote #2 for full citation); Unknown, "Process Fine Tuning Reduces HF Use," Chemical Engineering Progress, October 1996, pp. 20-22.

4 EDF, 1999; and New Jersey Department of Health and Senior Services, 1998 (see endnote #1 for full citations).