Exposure to boron

National Institute for Occupational Safety and Health, US Department of Health, Education and Welfare Criteria for a Recommended Standard... Occupational Exposure to Boron Trifluoride. DHEW (NIOSH) Pub No 77-22, Washington, DC, US Government Printing Office, 1976... 

Lee, I.R, R.J. Sherins, and R.L. Dixon. 1978. Evidence for induction of germinal aplasia in male rats by environmental exposure to boron. Toxicol. Appl. Pharmacol. 45 577-590. 

To obtain other diastereomeric hexoses, 30, obtained from (-)-26, was first converted into the benzoate 41. On exposure to boron trifluoride,19 41 furnished 43, through 42, after methanolysis. Employing the same procedure above, 43 was converted to the hemiacetal 44 which furnished L-galactose via route A and D-galactose via route B (Scheme 12).12... 

Now, everyone with a rudimentrary background on metal hydride reductions knows that a formal addition of the elements M-H to the C=0 bond takes place at a first stage. There is no reason to believe that anything different occurs to a close relative of carbonyls such as the hydrazone group upon exposure to boron hydride. On that account, the postulation of structure IV is as reasonable as the metal alkoxides that have always been proposed for analogous reductions of aldehydes and ketones (see Scheme 8.1). 

Few studies have been conducted on the harmful effects of exposure to boron and its compounds. Some evidence suggests that the element and its compounds may cause irritation of the eyes, skin, and respiratory system. No serious long-term problems, such as cancer, have yet been associated with exposure to boron or its compounds. 

Single acute exposures to boron are well tolerated. Reversible irritation to the respiratory tract and mucosal membranes may be seen initially but these are expected to resolve themselves. Chronic exposures can lead to anorexia, weight loss, vomiting, mild diarrhea, erythematus rash, alopecia, convulsions, anemia, and kidney damage. Both vomitus and feces will be blue-green. 

Similarly, 10-(4-mcthylphenylsulfonyl)bicyclo[6.2.0]decanol undergoes ring expansion-contraction upon exposure to boron trifluoride or alumina yielding /erm-fused bieyclo[7.1.0]decan-2-one (10)63. 

Toxicity Boron trifluoride (and organic complexes such as Bp3-etherate) are extremely corrosive substances that are destructive to all tissues of the body. Upon contact with moisture in the skin and other tissues, these compounds react to form hydrofluoric acid and fluoroboiic acid, which cause severe burns. Boron trifluoride gas is extremely irritating to the skin, eyes, and mucous membranes. Inhalation of boron trifluoride can cause severe irritation and burning of the respiratory tract, difficulty breathing, and possibly respiratory failure and death. Exposure of the eyes to BF3 can cause severe burns and blindness. This compound is not considered to have adequate warning properties. Boron trifluoride has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. Chronic exposure to boron trifluoride gas can cause respiratory irritation and damage. 

There is litde information on the health effects of long-term exposure to boron. Most of the studies are on short-term exposures. The Department of Health and Human Services, the International Agency for Research on Cancer, and the US Environmental Protection Agency (EPA) have not classified boron with regard to its human carcinogenicity. One animal study found no evidence of cancer after lifetime exposure to boric add in food. No human studies are available [102]. 

A TLV ceiling of 1 ppm (3 mg/m ) for exposures to boron trifluoride has been adopted by the American Conference of Governmental Industrial Hygienists. [1] The U.S. Occupational Safety and Health Administration similarly has adopted a ceiling limit of Ippm (3mg/m ) for exposures to boron trifluoride. [2)... 

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