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Response to Comment on “Butyltin Contamination in Marine Mammals from North Pacific and Asian Coastal Waters” SIR: We appreciate the opportunity to respond to the comments of Baldwin regarding our paper (1). We would like to address the issues he raised pertinent to the use of marine mammals for environmental research. As scientists who are focusing their research on environmental pollution, we have recognized the strict and severe conditions under which we have to conduct our work. Nevertheless, the difficulty of collecting samples needs to be overcome because we believe that toxicological studies on marine mammals have to be done in order to understand fully how these animals have become vulnerable to toxic chemical pollution. During the last three decades, 65 incidents of mass mortality and pathological symptoms were reported to have occurred in marine mammals (2). Interestingly, 9 out of the 11 reported mortality incidents in the 20th century happened after the 1970s. Although the causes for these occurrences remain uncertain or unclear, its potential relationship with toxic chemical pollution arising from rapid industrialization in recent years has been suggested (3). Previous studies likewise revealed that marine mammals have the ability to amplify much greater amounts of these toxic contaminants through feeding and also to pass them in large quantities from one generation to the next through lactation (4). Moreover, it has been found that these animals have a smaller capacity for degradation of these contaminants due to lacking or weak enzyme systems. These aspects are serious disadvantages to marine mammals because it may lead to bioaccumulation of these toxic chemicals (4). Based on the aforementioned conditions, it is our belief that scientists must develop research programs to help save marine mammals from the threat of these toxic chemicals. These research programs may be in the form of monitoring or toxicological studies. The former would entail the use of deal animals, while the latter would require the use of live animals. Since the toxic threat to marine mammals is quite serious, the conduct of both type of research programs is recommended. In the course of our research, however, species of larger populations were considered, and endangered species of animals are never used. Needless to say, we believe that scientists must try for the maximum achievement using the minimum number of samples. In closing, it must be said that as scientists we have the responsibility to make our data available to both the academia
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and the public in order to keep everyone informed of whatever scientific fact or finding our studies may reveal. It is in this context that we are grateful to the editors and peer reviewers of this journal for having considered monitoring and toxicological studies, such as ours and those of other scientists, worthy of publication. We can only hope that academic societies, policy makers, and the general public will be more understanding toward the conditions under which scientists, who are engaged in environmental pollution and ecotoxicological research programs conduct their work.
Literature Cited (1) Tanabe, S. Prudente, M.; Mizuno, T.; Hasegawa, J.; Iwata, H.; Miyazaki, N. Environ. Sci. Tech. 1998, 32, 193-198. (2) Colborn, T.; Smolen, J. J. Rev. Environ. Contam. Toxicol. 1996, 146, 91-172. (3) Simmonds, M. In Marine mammal epizootics worldwide; Proceedings of the Mediterranean International Workshop. Pastor, X., Simmonds, M., Eds.; Greenpeace International Mediterranean Sea Project: Madrid, Spain, 1991; pp 9-19. (4) Tanabe, Iwata, H.; Tatsukawa, R. Sci. Total Environ. 1994, 154, 163-177.
Shinsuke Tanabe Department of Environment Conservation Ehime University Tarumi 3-5-7 Matsuyama 790-8566, Japan
Maricar Prudente Science Education Department De La Salle University Taft Avenue, Manila 1004 Philippines
Hisato Iwata Department of Environmental Veterinary Sciences Graduate School of Veterinary Medicine Hokkaido University N18 W9 North Ward Sapporo 060-0818, Japan
Nobuyuki Miyazaki Otsuchi Marine Research Center Ocean Research Institute The University of Tokyo Akahama, Otsuchi Iwate 028-1102, Japan ES982002D
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