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Environmental Factor, November 2012

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Birnbaum gives keynote at Chesapeake Bay watershed meeting

By Eddy Ball

Linda Birnbaum, Ph.D.

Environmental exposures during windows of susceptibility, such as during infant and child development, may trigger health effects that manifest years or even decades afterwards, Birnbaum told the audience. (Photo courtesy of University of Illinois)

Chesapeake Bay map

This U.S. Department of Agriculture watershed map shows the portions of the six states whose runoff flows into the Chesapeake Bay.

NIEHS/NTP Director Linda Birnbaum, Ph.D., spoke at the Oct. 10 annual meeting of the Pesticides and the Chesapeake Bay Watershed Project in Reisterstown, Md.

Birnbaum’s talk explored the health effects of exposure to low doses of endocrine-disrupting chemicals (EDCs), as she has in other venues before groups of scientists. But, her audience this time also included politicians, government regulators, advocacy groups, farmers, and residents who live and work along what is America’s largest estuary and one of its most diverse.

According to the state of Maryland, Chesapeake Bay’s drainage basin covers more than 64,000 square miles with water, waste products, and runoff entering the bay from more than 150 rivers and streams in the District of Columbia and six states, potentially impacting the lives of some 17.5 million people who live there.

People in the basin are accustomed to hearing warnings about industrial pollution and parasite-laden shellfish, but Birnbaum’s presentation outlined an emerging paradigm of dose response to endocrine-active chemicals in pesticides and other products that can also impact human and animal health now and for generations to come.

Should we be concerned?

Right at the beginning of her talk, Birnbaum posed the question on virtually everyone’s mind about the dramatic increases in rates of complex and chronic diseases with a known environmental component. Reports of testicular cancer, hypospadia, breast cancer, low sperm count, diabetes, autism, asthma, and attention deficit hyperactivity disorder, she noted, have increased as much as 50 percent or more in recent years.

Genetic changes don’t occur that quickly in a population, she said, but over recent decades, the environment, from the chemicals in our homes to the food we eat, has changed fundamentally.

“There are unanticipated effects of exposure to toxic chemicals,” she told the audience, and our research must extend to health endpoints beyond cancer and birth defects. “NIEHS is supporting research on the developmental origins of obesity and the theory that environmental exposures during development play an important role in the current epidemic of obesity, diabetes, and metabolic syndrome,” Birnbaum said.

EDC exposure at home, at work, at play

This new research, Birnbaum continued, is based on a conceptual shift in thinking about chemical exposure to pesticides and other EDCs. “Whereas we used to think that higher doses are bad and lower doses are not as bad, we now know that low-dose effects from some chemicals that can act like hormones can have a substantial impact on our health,” she explained. She also said that new research has pointed to the persistence of susceptibility long after exposure, through epigenetic alterations in gene expression.

These changes in gene expression are increasingly linked to later development of obesity, diabetes, and neurological disease. Birnbaum pointed with pride to NIEHS research that has led to banning or limiting use of some pesticides, as well as to ongoing work by grantees, the Agricultural Health Study, and the National Toxicology Program (NTP) on additional long-term effects of exposure.

Commitment to public health

While the focus of the meeting was pesticides, Birnbaum’s presentation also covered the range of activities at NIEHS and NTP, from the development of predictive toxicology and studying the challenges of global climate change, to emerging issues related to nanotechnology, fracking, and health effects from the Gulf oil spill. She also shared with her audience the key components of the NIEHS 2012-2017 strategic plan, as they shape environmental health science research, translation, and their impact on public health.

Birnbaum closed with a new vision for NIEHS and NTP that maximizes resources through partnerships with sister NIH institutes and federal agencies, and addresses complex diseases and complex environmental impacts through transdisciplinary approaches.

“Our job doesn’t stop with the publication of scientific results,” she concluded. “We have an obligation to help translate the fruits of our research investments into public health interventions, policy, and preventive clinical practice, to provide the best protection of human health.”

An interagency cross-disciplinary effort toward improving watershed health

The Pesticides and the Chesapeake Bay Watershed Project meeting lineup of speakers and panelists reflected a convergence of several different scientific and regulatory interests.

In her invitation to Birnbaum, Executive Director of the Maryland Pesticide Network Ruth Berlin said, “Dr. Birnbaum’s March 14 commentary on low-dose effects of chemicals — particularly endocrine disruptors — generated a great deal of attention among our stakeholders and their colleagues.”

Because of this interest, Birnbaum ended up sharing the podium with U.S. Environmental Protection Agency environmental scientist Greg Allen and Wye Research and Education Center aquatic toxicologist Daniel Fisher, Ph.D. Allen previewed the upcoming report from EPA’s Chesapeake Bay Project, scheduled for release in November, on the impact of toxic contaminants on the bay watershed, while Fisher shared his recent work on the environmental impacts of contaminants, including the endocrine disruptive effects of land-applied poultry litter.

An afternoon panel discussion brought together Allen, who facilitates the project’s Research and Data Gaps Working Group, with colleagues from other project working groups:

  • University of Maryland Farm Management Specialist and organic farmer Erroll Mattox, who facilitates the Project's Collaborating with the Agricultural Community
  • National Oceanic and Atmospheric Administration Research Fishery Biologist Andrew Leight, Ph.D., who facilitates the Preventing Pesticides from Entering the Watershed Working Group
  • Andrew Fellows, Chesapeake regional director of Clean Water Action in Washington, D.C., and mayor of College Park, Md., who facilitates the Laws and Policies Working Group

EPA Environmental Protections Specialist Lee Tanner, who facilitates the Increasing Demand for Healthier Alternatives Working Group, had been scheduled to participate, but was unable to attend the workshop.

Citation: Birnbaum LS. 2012. Environmental Chemicals: Evaluating Low-Dose Effects. Environ Health Perspect 120(4):a143-a144.

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