Contaminants and Toxics

Whenever we mow our lawns, drive our cars, or throw away unused household chemicals, we face the potential of adding airborne or waterborne contaminants to the Chesapeake Bay. Multiply such compounds by millions of citizens in the watershed, and the resulting flows can be considerable. For a long time, the impacts of diffuse (nonpoint) flows seemed relatively small compared with those released by industry through factory discharge pipes or smoke stacks. But while large industrial sites have worked to decrease their outputs of potentially toxic compounds, diffuse sources of chemical contaminants have continued to increase, especially as population grows in the Chesapeake Bay watershed (projected to reach 19 million people by the year 2030).

These nonpoint sources are much more difficult to control, since there are few permits or other regulatory limits on many of these activities, some of which are simply part of daily life. In addition to chemicals like PCBs, chlordane, and mercury, more familiar items like pharmaceuticals and personal care products are now added to the long list of potentially toxic contaminants in the Bay. Chemicals associated with contraceptives, insect repellent, anti-bacterial disinfectants, caffeine, and fire retardants have all been found in the Bay.

Contaminants enter Chesapeake Bay regularly from land runoff, air deposition, surface water, and groundwater. Even potentially toxic compounds buried in sediments years ago can be resuspended by human activities such as dredging or by natural processes such as storms or burrowing animals. Once suspended, these contaminants can be transported by physical processes to new locations throughout the Bay. This means that even if a chemical is no longer in use today, it can still be a threatening pollutant in the Chesapeake.

Although pollution is a concern throughout the entire Chesapeake watershed, not all areas are contaminated equally. The multi-state Chesapeake Bay Program has identified Baltimore and Norfolk harbors and the Anacostia River in Washington, D.C. as "Regions of Concern" with regard to concentrations of contaminants. Other areas in the Bay region have periodically revealed unusual levels of chemical contaminants as well. A particularly mysterious event occurred in the South River in Annapolis in 2005. Although the river was thought to be relatively clean, surveys found that over fifty percent of brown bullhead catfish had tumors — a condition often associated with the presence of polycyclic aromatic hydrocarbons (PAHs), a pollutant generated by fossil fuel combustion. And yet measurements throughout the river did not indicate an abnormal level of PAHs in the sediment. Scientists are left stumped and looking for answers as to what is causing the cancerous growths. Is it a different pollutant? PAHs in another form? And once they find out which chemicals are to blame, they will have to discover where they come from.

What is being done about contaminants and toxics in the Bay?

Though contaminants and toxics are ubiquitous in our modern-day lives, it is still possible to limit their effects on the Chesapeake and its resources. The Chesapeake Bay Program’s Toxics Subcommittee is responsible for implementing the Toxics 2000 Strategy as part of the Chesapeake 2000 Agreement. The Strategy calls for a Chesapeake Bay “free of toxics,” which they define as “levels that result in no toxic or bioaccumulative impact on the living resources that inhabit the Bay or on human health.”

As part of the effort, the Toxics Subcommittee has characterized the severity of contamination in the Bay’s tidal rivers to help focus management and monitoring. Their designations include “Region of Concern,” “Area of Emphasis,” “Area with Low Probability for Adverse Effects,” and “Area with Insufficient or Inconclusive Data.” Included in the Toxics 2000 Strategy is the goal of reducing nonpoint sources of contaminants to Regions of Concern by at least 30 percent of 1998 levels by 2010. While work is underway, with so many Bay environmental issues competing for attention and resources, securing enough funding to accomplish the goals set by the Toxics 2000 Strategy presents a constant challenge.

Maryland Sea Grant articles and education briefs on toxics in the Chesapeake Bay

Chesapeake Quarterly articles

Recovering the Anacostia: An Urban Watershed and its Future
Vol. 2 No. 2 2003

Of Microbes & Messes: Bacteria Hold Key to Cleaning Up Polluted Groundwater
Vol. 5 No. 1 2006

Maryland Marine Notes articles

Bringing the Anacostia Back
January-April 1999

Toxics Report Highlights
Nov-Dec 1996

Why Are Toxics So Difficult?
Nov-Dec 1996

The Trouble with Toxics in the Bay
Nov-Dec 1996

Education Brief

Contaminants and the Chesapeake: Toward a Contaminant-Free Bay
html & pdf

Useful Links

Chesapeake Bay Program

Pollutants
PAH info

Maryland Department of the Environment

Fish and Shellfish Contaminant Monitoring

Past Work

Chemical Contamination in the Chesapeake Bay [workshop report]

Contaminants Research: Chesapeake Environmental Effects Committee

Chesapeake Ecotoxicology Research Program (CERP)