Exr LETTERS
Cancer risk Dear Sir: Paolo Ricci and Lawrence Molton wrote a useful overview of the rationale for cancer risk assessment, “Regulating cancer risks” (ES&Z lune 1985, pp. 473-79). However, they did provide a misconception in their discussion of chloroform. They chose this chemical to illustrate comparative risk-the balancing of the health risk of a substance with the associated risk of not using it. Thev state: “This was amlied in the decisihn to use chloroform,’a potential carcinogen, to kill bacteria in drinking water.” Of course, chloroform is not added to drinking water to kill bacteria but is an unintentional reaction product of the disinfectant chemical, chlorine. Although I am certain most readers are aware of this point, we should be careful to avoid causing confusion among any segment of the wide readership you enjoy. Steve E. Hrudey University of Alberta Edmonton, Alberta T6G 2G7,Canada
%e authors reply: We thank Steve Hrudey for his comment. Indeed, chlorine is used as a disinfectant in water, and CHC1, is an unwanted by-product of this process. The
CometHalley:
h c e in aLifetim1 h k s at Halley’y’sComet through the eyes of history.culture, and science. Spans 2200 y s u s of
I
Comet fact and fantas lnclvdes a complete guide to comstmtchingin !k86. Color photos. lavishly dludrstd, 190 pages; $12.96 paperhick, $19.; budhael. Call TOLL FREE IBWI424.6747 and charge your b w k to your credit cud. Or order from: American Chemical Society,DistributionOffice De t 126. 1155 16th Street, N.W.. Washington. DC If not satisfied. return within I5 days for Ifull refund or chuge credit.
h36.
758 Environ. Sci. Technol.. Vol. 19. No. 9, 1985
I
National Interim Primary Drinking Water Regulations are based on the annual average of the sum of the concentrations of chloroform, bromoform, bromodichloromethane, and dibromochloromethane (I).Our example of chlorw form stems from its king considered a carcinogen (2, 3). Although it is CIz that is added, for the risk assessor the implied balancing is between the risk from exposure to pathogens in water and the risk from Clz by-products. The regulation of risk often focuses on the ultimate carcinogen rather than on its precursor (3).
misused by advocates, both for and against, on the issue of incineration of hazardous wastes. In addition, it was inappropriate to use a scientific report that was still undergoing revision, the conclusions of which were subject to further change. Second, Bond states that the SAB report “awaited only the EPA administrator’s signature for final release.” This statement is false. No SAB report has ever awaited an EPA official‘s signature before. its publication. This is in keeping with the board’s congressionally mandated independent status with respect to EPA and other interested parties. No References agency officialhas the authority to exer( I ) COtNVO. 1. A. I n “Water Chlorination: cise either editorial or substantive conEnvironmental Impact and Hcallh Effects”, trol over any SAB report. Aon Arbor Science: Ann Arbor. Mich., Finally, the article offers selective 1983. VoI. 4 (2) ,Office of Water Supply. “Statcmcnt of Baverbatim quotations fromthe December 91s and Purpose for an Amcndmcnt to lhc 1984 draft SAEI report. A reader of just National lnlcrim Pnmary Drinking Water these excerpts could reasonably infer Rcgulalions on Trihalomethaner”; bvironmental Protection Agency: Washington, that the board adamantly opposed the D.C., 1978. incineration of hazardous wastes. (3) CNmp, K. S. In “ W a s r Chlorinalion. EnAlthough it is true that the SAB’s final vironmental Impact and Hcallh Effccls”. report, issued April 5, 1985, stated nuAnn Arbor Scicoce: Ann Arbor. Mich.. 1983: Vol. 4. merous and significant concerns about the quality of EPA‘s technical analyses, Ocean incineration one of its main assumptions reads as Dear Sir: Desmond Bond’s View, follows: “This Committee has been “Ocean incineration of hazardous asked to address the shortcomings and wastes: An update” (€S&T, June 1985, needs of this program, and its comments pp. 486-87). contains several signifi- should be considered in the light of what cant fachlal errors and omissions. First, probably is, in fact,a valuable technolBond asserts that a report on incinera- ogy . . . the committee’s comments, tion of hazardous wastes by EPA’s inde- both positive and negative, should be pendent Science Advisory Board (SAB) interpreted by the Agency and the public ”was suppressed” at a March 1985 as a desire to strengthenalready existing meeting of the International Maritime incineration programs rather than to disOrganization Scientific Group on continue what is already in place.” Dumping. Although he correctly notes ~F.YOSie that a draR of the SAB report was pubDirector, Science Advisory Board licly circulated in December 1984, he Environmental Protection Agency fails IO note several impolrani points Washington, D.C. 20460 affecting the context in which the draft document was made available. The EPA representatives who at- Dear Si:Desmond Bond‘s View in the tended the London session attempted to lune issue discusses the March 1985 caution the participants against using the meeting of the International Maritime S A B report, which at that time had no Organization (IMO) Scientific Group official standing. These cautionary on Dumping. Bond suggests that the statements were consistent with the board’s own wish that its report not be (conrimed on p . 761)
