LETTERS Diesel exhaust Dear Sir: After reading your article entitled, “Diesel exhaust: regulations and health effects” (ES& T , February 1980, p 135), I would like to make a few comments. First, the study by Schenker and Speizer is not in progress. I understand they are looking for funding and could begin work after obtaining a sponsor. As discussed in my paper, given a t the same symposium where Calabrese and Schenker delivered their presentations, currently in progress is an epidemiological study designed to evaluate mortality trends and cancer incidence among an occupation cohort exposed to diesel exhaust. This study, being carried out by Environmental Health Associates ( E H A ) as part of the Coordinating Research Council air pollution research program, is scheduled for completion by 1982. EHA will evalu-
ate the medical records from a northern California union of heavy equipment operators. Mortality patterns in the selected cohort will be compared to those expected among other males of the same age in California or other appropriate areas within the United States. The hypothesis of the mortality study is: Do men exposed to diesel exhaust exhibit different mortality patterns than similar workers without exposure to diesel exhaust? This study will evaluate cancer incidence and mortality data and involves approximately 30 000 individuals with up to 500 000 man-years of exposure. With respect to the comments on the London Transport study, there are many variables in that study which tend to make that effort a good deal more reliable than is implied in your article. That study has a tendency to overestimate the cancer and respiratory illness statistics while underesti-
mating the background mortality ratios. This was accomplished by including all workers with reported incidence of disease as part of the numerator while using only mortality (death) data in the denominator. The members of the extremely large cohort evaluated in this study are believed by the authors to have similar smoking histories to those found among the general population. The reference by Calabrese that diesel exhaust exposures may be associated with decreased pulmonary function can be subject to misinterpretation. Of the existing pulmonary function studies among subjects exposed to diesel exhaust, only one study has demonstrated any significant decrement in pulmonary function that could be related to exposure from diesel exhaust. This reference was taken from a nonpublished epidemiology paper reported by Robert Reger (1). This study had mixed results in both the lung function and symptomatology data. Where comparisons using years of underground exposure were made, the observed tredds were statistically insignificant. Symptomatology and lung function data did not have sufficient consistency that could allow definitive conclusions regarding diesel exposures and health effects. Dennis S. Lachtman Director, Health Sciences Envirotech Corp. Menlo Park, Calif. 94025 (1) Reger, R.; Hancock, J. “Coal miners exposed to diesel exhaust emissions,” In “,Proceedings, Health implications of new energy technologies,” Park City, Utah, April 1979.
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Environmental Science & Technology
Morel named associate editor Dr. FranGois M. M. Morel of the Massachusetts Institute of Technology has been designated associate editor of ES&T by the editor, Russell Christman. A member of the ES& T advisory board since 1978, Morel will concentrate his editorial activities on the research section of ES&T. H e is associate professor of civil engineering at M I T and is especially interested in the interactions between chemical pollutants and microbiota in aquatic systems.
