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Polychlorinated Biphenyls (PCBs)
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What are PCBs?
DRBC staff monitor for PCBs in the Delaware Estuary. Photo by DRBC. 
DRBC staff monitor for PCBs in the Delaware Estuary.
Photo by DRBC. 

What are PCBs?

PCBs are a class of chemicals used as coolants and lubricants in transformers, capacitors and other electrical equipment because they don't burn easily and are good insulators. 

In fact, the chemical stability of PCBs led to their use in hundreds of industrial and commercial applications.

Over 1.5 billion pounds of the substance was produced before it was banned in the U.S. in the late 1970s.

  • PCB Fact Sheet (pdf)


Why the Concern?

PCBs have been classified by the U.S. EPA as a probable human carcinogen.

Despite being banned in the 1970s, equipment containing PCBs is still in use due to the extended life span of the equipment. That stability also allows PCBs to persist in the environment. Today, in the waters of the Delaware River Estuary, PCBs can be found at concentrations up to 1,000 times higher than the water quality criteria.

There are numerous sources of PCBs in the Delaware Estuary. They include contaminated sites, non-point sources, industrial and municipal point source discharges, municipal sewer systems, the mainstem Delaware River above Trenton, tributaries to the Delaware both above and below Trenton, the atmosphere, sediments, combined sewer overflows (CSOs) and the Atlantic Ocean.

PCBs enter fish and other wildlife through absorption or ingestion and accumulate in their tissues at levels many times higher than in the surrounding water and sediment.

High levels of PCBs in fish have resulted in state-issued fish consumption advisories, which restrict or limit consumption of certain species caught in the Delaware Estuary. These state-issued fish consumption advisories prompted the Delaware Estuary (the tidal Delaware River and Delaware Bay) to be listed as impaired, requiring the establishment of a PCB total maximum daily load (TMDL). 
DRBC's Role in Reducing PCBs


What is a TMDL?

A TMDL expresses the maximum amount of a pollutant that a water body can receive and still attain water quality standards.

At the EPA's request, the DRBC developed PCB TMDLs for the Delaware Estuary and implements a regulation requiring dischargers to track-down and reduce PCB loadings to the river (more below).


PCB TMDL Development

At the request of the three estuary states (Pa., N.J. and Del.) and the U.S. EPA, the DRBC has taken the lead in developing the technical basis for the PCB TMDLs for the Delaware Estuary (DRBC WQ Zones 2-6). 


The PCB TMDL for Zones 2-5 was established in 2003 and for Zone 6 in 2006. DRBC staff worked closely with its Toxics Advisory Committee (TAC), an expert panel of scientists and its TMDL Implementation Advisory Committee on these efforts.


Pollutant Minimization Plans

Beginning in 2005, the DRBC requires dischargers complete Pollutant Minimization Plans (PMP) to track down and reduce point source and non-point source PCB loadings from their facility sites.

This collaborative effort has proven quite successful; PCB loadings in the Delaware River Basin have been reduced by ~70% overall (76% reduction from the top ten dischargers) since the requirement began.


DRBC Adoption of Updated Water Quality Criterion

In 2013, the DRBC adopted updated water quality criterion of 16 picograms/liter for PCBs in the Delaware Estuary for the protection of human health from carcinogenic effects. The updated PCB criterion, developed under the guidance of the TAC and based upon the most current methodology and scientific data available, is now a uniform value for DRBC Water Quality Zones 2-6. 


DRBC PCB Monitoring

The DRBC has a long-term dataset on PCBs and other pollutants in the Delaware River Estuary, monitoring surface water, sediment and fish tissue. Data are collected to support TMDL implementation, providing precise and defensible data on PCB concentrations in the Delaware River Estuary.

In 2024, the DRBC will deploy passive samplers at 5 sites in the Delaware mainstem from Lewes, Del. to Trenton, N.J. And, sediment samples will be collected in 12 tributaries and analyzed for PCBs, Organochlorine pesticides, Dioxins and Furans.


Point Source Discharge Monitoring

The DRBC also requires monitoring from point source dischargers.
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