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.
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.
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
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.
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.
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.
parallel between this human study and the offspring effects in wildlife
was interesting as well as troubling.