Emily Notch
Environmental Estrogen
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 estrogen-induced
cancer.
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 carcinogens.
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 Toxicology.
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."
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