represented by C14H8; probably pyracylene (or cyclopentr,g]acenaphthylene) (11) and possibly its isomer cyclopent[b,c]acenaphthylene (V) which do not appear to have been isolated or synthesized.
Acknowledgment The authors are indebted to Mrs. M. Hill (M. J. Reade) for help with the mass spectrometric measurements. Literature Cited Anderson, A. G., Wade, R. H., J . Amer. Chem. Soc., 74, 2274, (1952). Beynon, J . H., Williams, A. E., “Mass and Abundance Tables for Use in Mass Spectrometry,” Elsevier, London, 1963. Clar, E. “Polycyclic Hydrocarbons,” Vol. 1, Academic Press, London and New York, N.Y.; Springer-Verlag, Berlin; Gottingen, Heidelberg, 1964.
Crittenden, B. D., Long, R., ”Combustion and Flame,” in press, 1973. Edwards, R. A,, Fagerson, I. S., Anal. Chern., 37,1630 (1965). Homann, K . H., Wagner, H. Gg., Eleventh Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pa., p 373,1967. McNeil, D., Coal T a r Research Association, Gomersal, Yorkshire, England. private communication, 1972. Shultz, J. L., Kessler, T., Friedel, R. A,, Sharkey, A. G., Fuel, 51, 242 (1972). Tompkins, E. E., Long, R., Twelfth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, Pa., p 625, 1969. Wallcave, L., Enciron. Sci. Technol., 3, 948 (1969).
Received for review December 12, 1972. Accepted March 16, 1973. This investigation L C ~ Ssupported by Grant AP00323 from the National Center f o r Air Pollution Control (now Encironmental Protection Agency) o f the Department of Health, Education and Welfare.
CORRESPONDENCE
Determination of Bis(chloromethy1) Ether at Ppb Level in Air Samples by High-Resolution Mass Spectroscopy SIR: We wish to call the attention of your readers to a recent article in this Journal [Enuiron. Sci. Technol., 6, 930-2 (1972)l by L. Collier of the Rohm and Haas Co., Philadelphia, Pa., on the “Determination of Bis(ch1oromethyl) Ether a t Ppb Level in Air Samples by H i g h - h s o lution Mass Spectroscopy.” The development of a reliable analytical method for the determination of bis(ch1oromethyl) ether (BCME) in air a t the ppb level is a noteworthy contribution. However, the author states that BCME is “extremely toxic”; this statement is misleading since Laskin et al. [AMA, Arch. Enuiron. Health, 23, 135 (1971)] showed that the compound is a potent lung carcinogen to rats exposed to it at 0.1 ppm. The carcinogenicity of this compound and of chloromethylmethyl ether, using other biological test methods, has been reported earlier [Van Duuren et al., AMA, Arch. Enuiron. Health, 16, 1472 (196811. Furthermore, the American Conference of Governmen-
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tal Industrial Hygienists recently published “Threshold Limit Values (TLVs) for Chemical Substances and Physical Agents in The Workroom Environment With Intended Changes for 1972.” In this list, chloromethylmethyl ether and bis(chloromethy1) ether are included as human carcinogens. TLV’s for these compounds were not assigned. They recommend that for these substances “no exposure or contact by any route, respiratory, skin, or oral, as detected by the most sensitive methods, shall be permitted.” 6. L. Van Duuren S. Laskin 6. M. Goldschmidt Institute of Environmental Medicine New York University Medical Center New York, N.Y. 10016
