Emily Notch spent four years involved in salmon habitat
restoration in the Pacific Northwest before she decided to turn her
attention to research addressing the larger issues concerning the
biological effects of toxicants on freshwater fish.
Now, three years into her doctoral research at the University of Maine,
Notch has found evidence that waterborne synthetic hormones, like those
in oral contraceptives and hormone replacement therapies, do more than
impair fish reproduction. Synthetic estrogens and similar hormones have
the potential to disrupt an aquatic organism's natural ability to
perform DNA repair, which could lead to mutations and tumors.
Her work has implications not only for fish, including endangered wild
Atlantic salmon, but also humans.
"There's so much that we don't understand about what we're putting into
the environment and how it affects aquatic organisms," says Notch, a
native of Scotia, N.Y., who was recently named one of 66 graduate
students nationwide to receive a U.S. Environmental Protection Agency
(EPA) Science to Achieve Results (STAR) Fellowship.
"Now the research is spinning into a cancer realm, which is how (the
focus) comes back around to (humans). What makes this research so
interesting to me is how it all ties together."
Synthetic hormones like estrogen, excreted by millions of women taking
oral contraceptives or hormone replacement therapies, enter the natural
aquatic environment via wastewater treatment plants. Estrogens are known
carcinogens, but current science lacks a complete understanding of
In her research as a Ph.D. candidate in the laboratory of Greg Mayer, an
assistant professor of molecular and environment toxicology, Notch has
studied the effects of one synthetic estrogen, ethinylestradiol (EE2),
in zebrafish and found it has the potential to suppress nucleotide
excision repair (NER) in organisms.
NER is the molecular pathway in organisms — from fish to humans —
capable of recognizing and repairing DNA damage caused by environmental
Notch's research findings on EE2's ability to decrease the expression of
multiple liver repair genes in zebrafish, a model organism for human
health, were published this past summer in the journal Aquatic
Now with three years of funding with the EPA STAR Fellowship, awarded to
graduate students in environmental fields, Notch will further study
whether environmental estrogens alter DNA repair, leading to increased
mutations and, ultimately, cancer.
Notch is UMaine's third EPA STAR Fellow in the past three years. In
2004, Ph.D. student Karen Merritt in civil and environmental
engineering, and Nicolas Blouin, a master's student in marine sciences,
were named fellows.
"For humans who take birth control, the question ultimately is what is
the effect on them long term," says Notch. "For fish, what is the effect
of swimming in estrogen, hydrocarbons, metals and other pollutants? The
subtle interactions — how they impact fish and have implications for
human health — are fascinating. A big puzzle to me."