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An excerpt from Chapter 2, Hand-Me-Down Poisons
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As Colborn tackled the wildlife files for a second time, her mind kept returning to the female gulls nesting together. She pulled out the papers by Fox and Fry and carefully reread them. She sensed that the "gay gulls," as someone had dubbed them, were an important piece of the puzzle, but she still didn't know how to put it all together. The feminization of the males was a consequence of disrupted hormones. That involved the endocrine system, which was composed of various glands that controlled criticula functions such as basic metabolism and reproduction. Well, that about summed up her knowledge of current endocrinology. She had taken courses in pharmacy school, but the intervening decades had revolutionized the field. And endocrinology was not standard fare in the training of ecologists. If she was going to pursue this line of inquiry, she would have to know more. Several new endocrinology textbooks joined the stacks of wildlife files on the top of her desk. Her first efforts to master the basics of the endocrine system proved frustrating in the extreme. The texts were dense, unreadable, and full o facronyms that forced one to keep flipping back to earlier pages. Colborn only began making headway when she found a practical, accessible text, Clinical Endocrine Physiology, which she kept within reach through the months that followed. As she focused on hormones, evidence that she had previously passed over gained new meaning. She recalled the keynote address by Bengtsson, the Swedish toxicologist who described how the size of fish testicles had diminished as contamination from synthethic organochlorine chemicals increased in the Baltic. Was this a sign of hormone disruption? She looked again at reports of abnormal mating behavior in bald eagles, which had preceded the appearance of eggshell thinning and the collapse of the eagle population. The birds had been disinterested in mating. Hormone disruption, Colborn now suspected. Other things struck her, too, as she read through the wildlife files. A pattern began to emerge. Birds, mammals, and fish seemd to be experiencing similar reproductive problems. Although the adults living in and around the lakes were reproducing, their offspring often did not survive. Colborn began to focus on studies that compared Great Lakes populations to others living inland. In every case, the lake dwellers, who appeared otherwise healthy, were far less successful in producing surviving offspring. It seemed that the contamination in the parents was somehow affecting their young. It dawned on Colborn that the human studies investigating the effects of exposure to synthetic chemicals had focused largely on cancer in exposed adults. Only a handful had looked for possible effects on the children of exposed individuals, but Colborn recalled reading one that had studied the children of women who had regularly eaten Great Lakes fish. She dug it out of her files and read it again. The study by Sandra and Joseph Jacobson, psychologists from Wayne State University in Detroit, had also found evidence that the mother's level of chemical contamination affected her baby's development. The children of mothers who had eaten two to three meals a month of fish were born sooner, weighed less, and had smaller heads than those whose mother did not eat the fish. Moreover, the greater the amount of PCBs, a persistent industrial chemical that is a common pollutant in Great Lakes fish, in the umbilical cord blood, the more poorly the child scored on tests assessing neurological development, lagging behind various measures, such as short term memory, that tend to predict later IQ. The parallel between this human study and the offspring effects in wildlife was interesting as well as troubling.
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