ANALYTICAL APPROACH
Carcinogenicity and Pesticides Principles, Issues, and Relationships
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ust published! A current perspective on the relationship between pesticides and cancer. A first-of-its-kind approach, this volume summarizes the latest thinking on the pesticides-carcinogenesis relationship, seen in the light of new findings in cancer research. In a blend of theoretical and practical infor mation, this timely work examines the process of carcinogenesis itself and society's attempts to strike a balance between increased agricul tural productivity and the risk of cancer. Be ginning with an overview that puts the topic in a historical perspective, Carcinogenicity and Pesticides unfolds to target key issues such as: • the uncertainty of data interpretation in predict ing whether a pesticide will cause cancer in humans • external factors that affect carcinogenesis • mechanisms of chemical carcinogenicity • structure-activity relationships • risk assessment • epidemiology of cancer and pesticide exposure Bruce Ames, originator of the Ames Test for carcinogenicity, concludes the book with a thoughtful discussion on current research findings and how they relate to decisions concerning widespread use of pesticides in society. If you are a scientist, policy maker, or regu lator concerned with the effects of pesticides on the environment, you'll find Carcinogenicity and Pesticides a valuable synthesis of contem porary thinking on a topic of critical importance. Nancy N. Ragsdale, Editor, U.S. Department of Agriculture
tions; and an aliquot of the acidic frac tion was esterified with diazomethane. The chromatograms of the methyl es ters of the Bronze Age resin and of the Pistacia resins confirm their close rela tionship. In both daylight and under UV light, the unknown resin can be dis tinguished from olibanum. However, the Bronze Age and the two terebinth resins produced a series of spots with Rf (retardation factor) values greater than that of the strong spots at 0.57. The absence of these spots from the mastic extracts suggests that the Bronze Age resin is structurally similar to the tere binth resin. TLC of the acidic fractions provides evidence that the Bronze Age resin (KW179) favors the Cyprus terebinth resin (Figure 3). The small, faint spots above Rf = 0.60 (which are dark in day light and pink under UV) are more pro nounced in the Chios terebinth chromatogram than in the Bronze Age or Cyprus terebinth chromatograms. The acidic fraction of the Bronze Age resin also produces spots at Rf = 0.54 and Rf = 0.42. The intensity and color of these spots resemble the stronger spots in olibanum; consequently, we have won dered whether the resin from Ulu Burun could be contaminated with
traces of olibanum. The TLC data from the neutral frac tions also support the hypothesis that the Bronze Age resin is a terebinth res in. In addition, the chromatogram from the Bronze Age resin favors the Cyprus terebinth resin—the spot at Rf = 0.43 in the Chios terebinth chromatogram is absent. Finally, TLC of the ethanol ex tract shows that the Bronze Age resin is neither olibanum nor mastic resins (Figure 4). Moreover, the Chios chro matogram has a spot at Rf = 0.46 that is not seen in the Bronze Age or Cyprus terebinth chromatograms. Future directions From the TLC data, it is clear that the Bronze Age resin originates from P. terebinthus. However, several ques tions still remain unanswered. For ex ample, is atlantica a distinct variety? Botanists disagree about whether there are different varieties of terebinth, yet our TLC data support the theory that at least two different varieties do exist. Furthermore, do the differences be tween the Bronze Age resin and the terebrinth resins result from evolution ary changes or chemical decomposi tion? We are continuing to study tere binth resin samples from different
Robert E. Menzer, Editor, University of Maryland Developed from a symposium sponsored by the Divi sion of Agrochemicals of the American Chemical Society ACS Symposium Series No. 4 1 4 2 4 7 pages (1989) Clothbound ISBN 0-8412-1703-3 LC 89-18052 $54.95 Ο
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American Chemical Society Distribution Office, Dept. 53 1155 Sixteenth St., N.W. Washington, DC 20036 or CALL TOLL FREE
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Figure 3. Thin-layer chromatography of the acid fraction. TLC was carried out on glass plates coated with a 250-/tm layer of silica gel developed to a height of 15 cm with methylene chloride containing 2 % acetone and visualized with chlorosuifonic acid (30% in acetic acid). Left: in daylight; right: under 354-nm UV light.
44 A · ANALYTICAL CHEMISTRY, VOL. 62, NO. 1, JANUARY 1, 1990
