Adverse Effects:

Anemia
Blood
Body Weight Decrease
Bone
Brain
Endocrine: Pituitary
Endocrine: Thyroid
Genotoxic
Kidney
Chemical Weapon Precursor for the production of Sarin-family nerve agents

September 1993 - Chemical Weapon Precursor chemicals that are also used as fluorine pesticides. A comparison of the Australia group list of chemical weapon precursors and the CWC schedules of chemicals, by RJ Mathews. Chemical Weapons Convention Bulletin. Issue No. 21. Page 2,

[pesticides highlighted in red]: "... some of the precursor chemicals which are early in the production process and/or are widely produced in industry (and hence not considered suitable for effective monitoring under the CWC [Chemical Weapons Convention]) have been included on the AGL [Australia Group List], because they are either known or suspected to have been sought for CW purposes. Such precursors include: ¥ the fluoride chemicals (14 [potassium fluoride], 24 [hydrogen fluoride], 41 [potassium bifluoride], 42 [ammonium bifluoride], 43 [sodium bifluoride] and 44 [sodium fluoride]) for the production of sarin-family nerve agents..." The list of precursor chemicals and their CAS Nos. appear on page 3. Also available at: http://fas-www.harvard.edu/~hsp/bulletin/cwcb21.pdf

1954 - A quantum-mechanical discussion of the bifluoride ion. Thesis by Martin Karplus. In partial fulfillment of the requirements for the Degree of Doctor of Philosophy. California Institute of Technology. Pasadena, California. Acknowledgements to several people (including Dr. Linus Pauling) were cited and also: "Generous financial assistance was supplied by the Allied Chemical and Dye Corporation."
Excerpts from Introduction:
... In spite of the recognized importance of the hydrogen bond, no one has given a detailed discussion of the forces involved in its formation. Since the bifluoride ion (FHF) is the simplest hydrogen bonded species, it appears best suited for a theoretical attack. This thesis is an attempt to develop a semi-theoretical method applicable to highly ionic systems and to apply this method to a treatment of the bifluoride ion. It is hoped that the results contribue to a better understanding of the hydrogen bond and provide an illustration of the power of quantum-mechanical methods in chemistry.

US EPA List of Inerts. This substance was on List 3.

Note: US EPA allows so-called "Inert" ingredients to be commonly mixed with the "active" pesticidal ingredient to create a formulated pesticide product. According to EPA, "The term `inert' is not intended to imply nontoxicity; the ingredient may or may not be chemically active." "Inert" ingredients include solvents, emulsifiers, spreaders, and other substances mixed into pesticide products to increase the effectiveness of the active ingredients, make the product easier to apply, or to allow several active ingredients to mix in one solution. Both US EPA and California Department of Pesticide Regulation require pesticide manufacturers to identify inert ingredients in their products but do not disclose this information to the general public because the pesticide industry considers product formulations trade secrets, protected by law and by the US EPA. The US EPA category of Inerts (as of September 2003):

List 1 - Of Toxicological Concern
List 2 - Potentially Toxic / High Priority for Testing
List 3 - Of Unknown Toxicity
List 4A - Generally Regarded as Safe
List 4B - EPA states it has Sufficient Information to Reasonably Conclude that the Current Use Pattern in Pesticide Products will not Adversely Affect Public Health or the Environment
List 4 (all)

See good report: Toxic Secrets": "Inert" Ingredients in Pesticides 1987-1997, published by Northwest Coalition for Alternatives to Pesticides.

Inert Ingredients No Longer Used in Pesticide Products - Former List 3 Inert.

EPA is removing certain chemicals from its list of pesticide product inert ingredients that are not currently used in pesticide products. Future use of these chemicals as inert ingredients in pesticide products will not be permitted unless a petitioner or registrant satisfies all data requirements as identified by the Agency, and the Agency is able to make a determination that the use of the inert ingredient will not pose unreasonable risk to human health or the environment. All tolerances or exemptions from the requirement of a tolerance for the use of these chemicals as inert ingredients in food- use pesticide formulations will be proposed for revocation at a later date in a separate Federal Register Notice.