ES&T
LETTERS Trace analyses Dear Sir: The article of John Glaser et al., "Trace Analyses for Wastewa ters" (ES&T, Vol. 15, No. 12, 1981, pp. 1426-1435) details a procedure for estimation of the method detection limit ( M D L ) . It appears that this procedure would yield low estimates of the M D L . Formulation of a procedure for es timation of M D L is dependent upon interpretation of the definition of M D L . One interpretation leads to the following requirements of the statis tical test of the null hypothesis (no analytc present) using the laboratory determination of concentration: • If the analyte is not present, then the statistical test of the determination should yield the correct conclusion of absence 99% of the time. • If the analyte is present at the M D L level, then the statistical test of the determination should yield the correct conclusion of presence 99% of the time. This in effect defines the Type I and Type II errors of the statistical test (7) and requires consideration of two error distributions: distribution A — " t h e analyte absent" error distribution, and distribution Β—"the analyte present at the M D L mean level" error distri bution. The critical value C of the statistical test would be the 99th percentile of distribution A and the first percentile of distribution B. The coincidence of these percentiles is obtained by ap propriately locating M D L (i.e., dis tribution B). This procedure would yield an estimate of M D L that would be greater than that obtained from the authors' procedure in Equation 8, p. 1427. Reference (1) Ostle, B. "Statistics in Research"; The Towa State University Press: Ames, Iowa, 1963; p. 109. Ronald L. Jacobson Metropolitan Waste Control Commission 350 Metro Square Building St. Paul, Minn. 55101 Research support Dear Sirs: In his letter (ES&T, Vol. 15, No. 11, 1981, p. 1250), Dr. Needleman questions Dr. Jerome Cole's views on the grounds that they were 318A
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based upon studies ". . . supported by lead industry funds." Since when in the U.S. is the accused denied the right to have his evidence presented and fairly evaluated rather than summarily dis missed as biased on the mere fact that the defendant presented them? Since, however, Dr. Needleman raises this ethical question, it would seem only fair that his motives, too, be examined to determine whether, in fact, he himself is free of any bias. As a university professor, his record of research and publication is part and parcel of his claim to enhancement of his position, whether in status, research funds, salary, or whatever. I would venture that Dr. Needleman's studies had financial support for which he may have felt grateful to the extent that the results could easily have reflected that gratitude as well as an expectation of continued support. While conscious or unconscious bias is a factor in all human views, scientists can reasonably be expected to over come them at least to the extent that only supportable claims are put forth over which reasonable differences of opinion can be argued on scientific grounds. If that argument is reduced to charges equivalent to a personal lack of integrity, I can only conclude that the one raising that question might well be just as much suspect as the one he has charged. I. W. Tucker, Ph.D. Professor of Environmental Engineering (Emeritus) University of Louisville 1810 Crossgate Lane Louisville, Ky. 40222 Airborne dusts , Dear Sir: I have become disabled by an occupational dust disease, industrial asthma, and cannot go back to my job. From August 1973 to September 1981,1 worked for a tungsten carbide manufacturing plant, and was exposed to tungsten carbide, tantalum carbide, titanium carbide, niobium carbide, and cobalt—3% to 24% of matrix and graphite dusts. I hope my story saves some future workers from serious lung disease. In September 1981 I became dis abled by asthma. I had an initial physical and X-rays in August 1973, but no annual physical examination
was given or required by the company. To my knowledge, no air tests were ever conducted in the shop during my employment. N o prior asthmatic condition was present; I stopped smoking in 1977 (I was a moderate one-pack-per-day smoker prior to that time). My symptoms started in January 1981. Exposure to fumes from carbide fires in January 1981 and April 1981 caused severe attacks, followed by ill ness. My condition has been termed permanent-partial disability. Expo sure to these dusts is a health hazard; yet my employer told me it was a nui sance dust and could not hurt me or cause lung damage. Frank Johnson Syracuse, N.Y. 13205 Editorial excellence Dear Sir: I take this opportunity to express my congratulations for the general high quality of the feature ar ticles, news content, and research pa pers in ES& Τ over the past year. I am certain individuals have complaints about specific articles or news items. This is expected especially for science, which interacts substantially with management and policy in environ mental quality issues. Overall, I think you and your staff are doing a fine job—so much so that I am going to alter a recent pergonal policy com mitment not to subscribe to any more journals and place an order for a per sonal copy of ES& T. John W. Farrington Associate Scientist, Department of Chemistry Director, Coastal Research Center Woods Hole Océanographie Institution Woods Hole, Mass. 02543 The global future Dear Sir: Thank you for the copy of the article on "The Global 2000 Report," which appeared in ES&T, Vol. 16, No. 3, 1982. Bette Hileman presented the issues with balance, clarity, and thoughtfulness. I am glad to have it on hand to pass on to those wanting another overview of the report. Patricia Maimon Gerald O. Barney & Associates, Inc. Research on World Problems Arlington, Va. 22209
