LETTERS DDT, fact or fiction Dear Sir: The article, "DDT: A renaissance?" (ES&T. April 1974, p 322) would never pass a scientific review process for publication in any reputable journal; not only are there many inaccuracies, but a gross injustice is done to the work of many investigators. Several examples: "It is now well-known that PCBs produce an almost identical gas chromatograph (sic) to DDT and DDE." PCB compounds are readily distinguished from those of the DDT group on gas chromatograms of extracts of environmental samples, or c a n be otherwise distinguished. and have been so distinguished from the time of their discovery in the mid1960's. Many dozens of papers, including some which have appeared in Environmental Science & Technology. have since greatly refined the techniques of both detection and measurement of PCB. The argument that PCB could not be distinguished from DDT compounds and that many of the detrimental effects attributed to DDT might in fact be caused by PCB was presented by the DDT industry at the Madison DDT hearings in early 1969. Dr. Devlin repeats that argument, which was refuted at that time, and which has not been supported by any data subsequently obtained. "Before 1967, many of the reports on the quantities of DDT and D D E present in samples were exaggerated due to the presence of PCBs . . . " Residue chemists have long known that some gas chromatographic techniques do not separate the p , p ' DDT peak from a major PCB component, and some of the earliest values reported for p.p'-DDT were in fact too high. DDE (p.p'-DDE) is the most abundant of the DDT compounds in North American environmental samples; to m y knowledge no DDE values reported by any reputable laboratories at any time have been exaggerated due to the presence of PCB's. If Dr. Devlin has any data that would support his statement, particularly if the data pertain to a detrimental effect attributed to chlorinated hydrocarbons, h e would provide a service by producing them. . . thus invalidating any correlation between the amount of DDT found and the extent of eggshell thinning," in reference to studies carried out before 1967. Such a correlation between increasing DDE content and decreasing sheel thickness has since been found in many other species. The first such correlation was reported in 1968 by Hickey and Anderson (Science. 162: 271) who showed 'I.
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that a relationship existed between eggshell thickness and the DDE content of Herring Gull eggs. Such correlations have not been found for PCB or any other environmental pollutant, except when the amounts of those pollutants paralleled those of DDE. ". , . we cannot absolutely be sure of the accuracy of the methods." Surely this statement discredits the many papers which have appeared in the Journal of fhe Association of Official Analytical Chemists. The "detection" of several pesticides in soil samples that had been sealed since 1910 hardly supports the argument. Many compounds produce peaks on gas chromatograms obtained with the use of electron capture detectors. Only the sloppiest of chemists would "identify" one of these peaks as a pesticide with a similar retention time without carrying out confirmatory tests. The biological arguments advanced by Dr. Devlin are not m o r e accurate and could likewise be refuted point by point. No cause, political or otherwise, is well served by sloppy scientific arguments. The appearance of such arguments in the pages of ES&T hardly does credit to a distinguished journal. Robert W. Risebrough
University of California, Berkeley Bodega Bay, Calif. 94923
DDT response Dear Sir: Dr. Risebrough is well known for his extreme views concerning the use of DDT and is very active in this respect. He is also well known for skirting facts when they do not fit his particular picture of this compound. Dr. Risebrough implies in his letter that it has not been shown that PCB's cause eggshell thinning. I have enclosed parts of several papers proving his statement incorrect. I found these papers in a very short period of time and with only a very limited search of the literature. I am sure there are many more, and I am also sure that Dr. Risebrough is aware of them. You will find among the papers that I have enclosed a paper by Dr. Risebrough on PCB's, citing another paper by Risebrough and his coworkers, pointing out that PCB's are "powerful inducers of steroid hydroxylases in birds and, with p . p ' - D D E may therefore be partially responsible for the aberrant calcium physiology observed in species of raptorial and fish-eating birds which accumulate chlorinated hydrocarbons." They suggest in their paper
that this activity by PCB's (induction of steroid hydrolases) is one of the causes of eggshell thinning. I n his letter Dr. Risebrough goes to great lengths to explain that PCB's are distinguished from the DDT c o m pounds with a gas chromatograph as well as by other means, the implication being that I was unaware of this. However, in m y paper I clearly state that PCB's were not distinguished from the DDT compound prior to 7967. and it was during this time that many of the scare stories about DDT were produced. A s for DDE and the PCB's, Dr. Risebrough should read the following papers which clearly point out that PCB's are very likely to interfere with DDE in chromatographic analyses. McCloskey, L. R., Deubert, K. H., Bull. Environ. Contam. Toxicol., 10, 261-64 (1973). Greichus. Y . A,, Worman, J. J., Pearson. M . A,. Call, D. J., ibid.. 11, 113-20 (1974). Bagley, G. E., Reichel, W. L., Cromartie, E., J. Ass. Offic. Anal. Chem.. 53, 251-61 ( 1 9 7 0 ) . Armour, J. A,, Burke, J. A,, ibid.. pp 761-68. Reynolds, L. M . , Bull Environ. Contarn. Toxicol.. 4, 128-43 (19 6 9 ) . Again. the above papers were found with only a very short, limited search of the literature. There are many more. In his last paragraph Dr. Risebrough airily implies that he has refuted point by point my arguments for the continued use of DDT. A careful reading of my paper and his letter by anyone familiar with the DDT literature will show that he has not refuted anything . Robert M. Devlin University of Massachusetts East Wareham. Mass. 02538 Metals in water correction
Dear Sir: I read with interest, your article, "How much metal is there in our waters?" (ES&T. Feb. 1974, p 112). There is one correction I would like to make. Reference is made to the fact that " I n Nova Scotia, for example, in a river which carried effluent from mines of these metals, salmon , . .". There are, at the present time, no base metal mines in Nova Scotia, nor have there ever been any. If, in the future, such a mine wished to establish in Nova Scotia, the Department of the Environment would not issue a permit unless the company's effluent was properly treated. I believe the reference should have been made to the Province of New Brunswick. A. J. Crouse, Technical Director
Nova Scotia Department of the Environment Halifax, N.S.. Canada
