Bacteria from sewage are at more than 2,000 times healthy levels in tributaries to Baltimore County's Back River, according to a new report by the Johns Hopkins Bloomberg School of Public Health. But they are much lower and dropping at Sandy Point beach near Annapolis.
The school's first major report on the Chesapeake Bay examined pollution levels to try to determine what impact they have on the health of the 16 million people who live in the bay's watershed.
The authors, who studied numerous waterways in the Chesapeake region, didn't find any immediate threats to the public health. The quality of drinking water is generally good, the report said. And if people swim only at public beaches and limit their consumption of fish to the state's guidelines, they should be fine.
But levels of fecal coliform, bacteria found in raw sewage and animal and human waste, are extremely high in the Back River near Essex after storms. They ranged from 640 to 2,135 times higher than healthy levels at the two locations studied in 2001.
The U.S. Environmental Protection Agency worked with the Justice Department in 1997 to sue the city over its broken sewage system, which leaked into the Back River and other waterways. That led city officials to sign a consent decree promising $900 million in repairs and upgrades, which have begun.
Because there are no swimming beaches along that section of the Back River, the bacteria from sewage generally are not an immediate threat to people. But the waste contributes to the growing "dead zone" in the bay, where oxygen is insufficient for life, said Dr. Robert Lawrence, director of the public health school's Center for a Liveable Future.
People who fish or crab in the Back River should be sure to wash their catch and their hands, Lawrence said.
Fecal coliform has been below hazardous levels and dropping almost continuously since 1992 at the Sandy Point State Park beach near Annapolis, the one public beach studied by the researchers.
Although the school of public health doesn't usually focus on the bay, it decided to tackle the subject after severe outbreaks of the microbe Pfiesteria and algae blooms in 1997 raised questions about health risks.
"Unfortunately, the bay has not improved," said Kim Coble, Maryland executive director of the Chesapeake Bay Foundation, which helped with the study.
One of the report's authors said yesterday that scientists should conduct more studies on the trace amounts of drugs such as Prozac that are showing up in water supplies after being flushed through septic systems.
"Our waters have a little bit of Prozac in them, a little bit of oral contraceptive hormone, a lot of caffeine. ... The medicines you take today may be in the water tomorrow, and we need to understand that better," said Thomas A. Burke, a professor at the school.
The report said people whose fish consumption exceeds state guidelines face "potentially harmful levels of mercury exposure" and damage to their health from PCBs, a man-made chemical coolant.
For example, the new guidelines suggest that men eat no more than two rockfish meals a month, and that children and women of childbearing age eat no more than one such meal a month.