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Environmental Toxicology and Chemistry, Vol. 18, No. 7, pp. 1347–1348, 1999q 1999 SETAC

Printed in the USA0730-7268/99 $9.00 1 .00

Editorial

STEPPING STONES OF SCIENCE

For centuries, scientists have probed the origins and mys-teries of life and of our environment. Our present knowledge,most of which is taken for granted, rests upon the shouldersof the scientists who preceded us. The underpinnings of ourcurrent knowledge can be traced to earlier biological scientistssuch as Linnaeus, Darwin, Mendel, and Avery, and to chemistssuch as Priestley, Kekule, von Stradonitz, Richards, Aston,and Bloch. Many of the giants of science, however, are nowforgotten. What we know has become so ingrained in modernscience that we tend to forget that it once had to be discovered.

I arbitrarily consider the end of World War II to be thebeginning of the era of modern toxicological and environ-mental science. This period marked the onset of widespreaduse of many synthetic, persistent, toxic organic chemicals.Because of its spectacular success in controlling insects af-flicting humans all over the world, DDT was the first of thesechemicals to draw attention. With the use of DDT, insects suchas sucking lice and bedbugs virtually disappeared from theUnited States. Insect-borne diseases such as malaria and yel-low fever were eradicated in the United States and greatlyreduced worldwide shortly after the first few years of wide-spread use of DDT. Persistence was deemed a desirable trait.

The use of DDT also led to the first widespread awarenessof the need for evaluating its advantages and disadvantages,the field of study now called risk and hazard assessment. Thepublic began to ask questions about the long-term effects ofother persistent chemicals. Scientists were caught unprepared.They were embarrassed to realize how little they knew aboutthe long-term toxicity, transport, and fate of chemicals in or-ganisms, soil, water, and air.

Over time, new terms began to appear in the scientificliterature, terms such as bioconcentration, eggshell thinning,no-observable-effect concentration, LC50, chronic toxicity(mutagenic, carcinogenic, etc.), ppb, ppt, nuclear magnetic res-onance, gas chromatography, ozone depletion, radioactivetracers, ecology, and many others. An entirely new scientificlanguage had to be learned—one that either confused or fright-ened the general public. These terms signaled the advent ofnew sciences emanating from the laboratory. Upon discoveringa chemical’s potential usefulness, attempts were made to de-velop preliminary environmental test methods that were safe,practical, and economical. Initially, test methods were oftenstandardized under the auspices of trade associations or gov-ernment agencies. These test methods were attempts to sim-ulate real-world toxicity or physical situations. Before 1970,however, scientists were limited by current knowledge, avail-able test organisms, test methods, and the perception that thiskind of testing ranked low among economic and politicalneeds. Early attempts at developing test methods and stan-dardization were often commercially driven, the goal being toprove a product superior in some way for advertising advan-tage.

After the U.S. Environmental Protection Agency was es-tablished in 1970, development of environmental test methods

emphasized assessment of the safety of chemicals to humans,wildlife, and the total environment. Special attention was givento the chronic or persistent fate of chemicals. Relatively cheapand short-term acute studies were gradually replaced by in-creasingly costly studies of the long-term chronic toxicity andfate of chemicals in all segments of the environment. Stan-dardization of these new test methods was driven principallyby governmental laws and regulations.

The perceived and real toxic threats of synthetic chemicals(principally to humans and secondarily to wildlife) were wide-ly publicized in the news media and led to many real and somefalse temporary scare events. The public continually saw one‘‘expert’’ pitted against another ‘‘expert.’’ ‘‘Who can I be-lieve?’’ became a question frequently voiced in the generalpopulation. It was an adversarial situation based on too littlereal background knowledge and too much opinion.

These events led to an explosion in the numbers of scientistssearching for methods of detecting changes in our world, aswell as a broadening of the scope of the science needed tocompare long-term changes in such areas as climate; toxico-logical, geological, ecological, and environmental occurrencesrelated to the activities of humans and many more naturalevents that had previously been poorly documented or unre-corded. The scientists involved in some early basic investi-gations were mainly the taxonomists, agriculturists, horticul-turists, chemists, and meteorologists who established the basicsof their own specific sciences. It was not until later that sci-entists began to consider many other sciences related to theirown specialties. This was particularly true with regard to at-tempts to evaluate the risks and hazards of chemicals. Thepresent explosion in the discovery and distribution of infor-mation has been built on the development of a number ofsciences, including computer science, communications, andchemical analytical techniques. The need for interdisciplinaryscience led to the formation of the Society of EnvironmentalToxicology and Chemistry (SETAC) in 1979.

In earlier days, scientific articles were most frequently au-thored by one or two researchers. In 1983 and 1984, about16% of the articles (excluding editorials) in EnvironmentalToxicology and Chemistry (ET&C) had only one author, andthe average number of authors was three. In the 1995 and 1996volumes of ET&C, only about 2 to 3% of the articles had asingle author. The average number of authors per paper hascontinued to rise. As many as 25 authors have been listed forone article! These figures indicate an increasing use of inter-disciplinary sciences to solve environmental problems.

Perhaps the most exciting development in the field of en-vironmental science in the 1990s has been the use of DNAanalysis for ‘‘fingerprinting’’ and detection of genealogicallineage. Scientists can now define the evolution of organismsand make positive identifications of the daily activities of in-dividual members of a given species. The analysis of DNAhas also made possible the complicated process of gene iden-tification, leading to the detection of weak links in the genes

1348 Environ. Toxicol. Chem. 18, 1999 E.E. Kenaga

of humans and other organisms and to the detection of thegenetic sources of their abilities to resist diseases and debil-itating effects. With DNA analysis, we can look ahead to thepossibility of gene replacement for the potential improvementof organisms for commercial purposes and even for the in-creased health and survival of organisms. The effort to makegene replacement possible has been implemented by the am-bitious efforts of scientists who in 1990 began to ‘‘map’’ thethousands of genes that lie along all 23 human chromosomesand all 20 mouse chromosomes.

Understanding of the comparative toxicity of many haz-ardous components in common edible substances in the humandiet and their various routes of dissipation has resulted in thediscovery of DNA defenses against small concentrations ofmany toxic substances, both synthetic and natural. These toxicinsults are only successful when the DNA chain is broken anda different link is inserted, resulting in a foreign DNA moleculereplicating itself repeatedly. Thus, the long-held ‘‘single mol-ecule theory’’ for a toxicant causing mutagenic or carcinogeniceffects is highly unlikely. The defense system must be over-whelmed. Otherwise, people who have been exposed overmany years to secondhand smoke and synthetic chemicals suchas 2,4,5-T, TCDD, ethylene dibromide, and carbon tetrachlo-ride, or who have been exposed to experimental synthetic

chemicals by the tens of thousands in the course of their work,would have died long ago. This knowledge changes our con-ception of the concentrations of chemicals necessary to causetoxic effects as well as our conception of the consequent riskand hazard evaluation process. Thus, in addition to the ad-vances DNA analysis has brought about in existing sciences,the combination of increased analytical sensitivity—enablingthe identification of very small concentrations of DNA frag-ments—and the advanced understanding of genetic cellularactivity has made DNA analysis the ‘‘detective’’ for use in theexploration of future research frontiers.

Scientists building on the science of others produced thespectacular DNA analytical research techniques that can nowbe performed at relatively low cost and with simple instru-mentation. Since the 1960s, a succession of Nobel Prize ge-neticists, including Joshua Lederburg (the first recipient of theSETAC Founders Award), Maurice Wilkins, Frances Crick,James Watson, Michael Smith, and Kary Mullis, among others,have contributed to this research. Thus, we see again the mean-ing of the old adage, ‘‘The past is but prologue to the future.’’

Eugene E. KenagaSETAC President, 1979–1981Dow Chemical (retired)Midland, Michigan, USA