It is unsafe to eat certain fish & shellfish caught in the San Francisco Bay, because they have built-up toxic levels of Polychlorinated Biphenyls (PCBs) and mercury. Eating contaminated seafood can lead to health problems in humans and wildlife, including muscle weakness, brain damage, reproductive issues and even cancer.
Also known as “legacy pollutants,” PCBs and mercury were once commonly used in industrial and electrical applications, building materials, and household items. The U.S. has banned the production of PCBs for more than 30 years, and has limited modern-day mercury pollution, but past pollution continues to linger in Bay Area soils and waters today. Ever since the Regional Water Board found San Francisco Bay to be impaired, agencies across the Bay Area have worked together to try and reduce these pollutants. This includes finding and stopping pollution in local watersheds.
One source of these contaminants today is urban stormwater. To help, Santa Clara Valley municipal agencies have used innovative, effective control measures to reduce pollution at-the-source.
Federal, State and Local Regulations
Many agencies have taken legal and practical steps to reduce PCBs and mercury contamination:
- U.S. Environmental Protection Agency
- The Clean Air Act
- The Clean Water Act
- 303(d) impaired waters list
- National Pollution Discharge Elimination System (NPDES) stormwater permit program
- Specific bans and restrictions on PCBs and mercury
- CA Department of Health
- Mercury and fish contamination advisory and outreach for SF Bay
- San Francisco Regional Water Quality Control Board
- Declared SF Bay and local waters to be impaired, after years of fish tissue monitoring
- Set Total Maximum Daily Loads (TMDLs), creating healthy limits and pollution reduction goals – for municipal agencies to work toward protecting sport fishing, human health, and wildlife
- NPDES Municipal Regional Stormwater Permit
- Santa Clara Valley cities and counties
- Local ordinances to prevent non-stormwater discharges
- Requiring Low-Impact Development and transitioning to Green Stormwater Infrastructure to reduce/treat PCBs & mercury in stormwater runoff
- Finding management areas and source properties
- Conducting outreach to promote proper disposal of mercury-containing consumer goods, through Santa Clara County’s Household Hazardous Waste program
Sources of PCBs and Mercury Contamination
PCBs and mercury have different histories in California, but they both pose a public health risk to people eating fish from the San Francisco Bay today. Also known as “legacy pollutants,” these substances were once commonly used in industrial and electrical applications, building materials, and household items.
PCBs
PCBs are a group of man-made chemical compounds that were once used in many industrial, construction and electrical applications. They were widely used by many industries because of their low electrical conductivity, high boiling point, chemical stability and flame-retardant properties. The largest use of PCBs was in electrical equipment, including transformers and capacitors, but they were also widely used in a variety of other applications, including hydraulic fluids, dust control, flame retardants, lubricants, paints, sealants, wood preservatives, inks, dyes and plasticizers. PCBs have also been found in a variety of non-liquid materials, including construction materials such as insulation, roofing and siding materials.
PCBs were made in the U.S. for 50 years until the manufacturing of PCBs was banned in 1979. Their import, export and distribution in commerce were also banned, and PCBs uses were restricted to totally enclosed applications. The U.S. EPA has authorized other minor uses, but the unavailability of PCBs and health concerns ended their use in new applications. Demolition of older buildings are potential sites of ongoing concern.
Mercury
Mercury exists naturally in the Earth’s rocky crust as a stable element, but two things have led to harmful amounts of mercury in the Bay:
- Legacy and ongoing human activity has concentrated and released unnaturally large amounts of it into the environment (historic mercury, gold & silver mining in the 1800s and artisanal mining today, fossil fuel combustion, concrete production, consumer goods).
- Newly available mercury – from human activity – deposits from air, washes or seeps into local waterways, and is then turned into its toxic form (methylmercury) by bacteria that live in wet soils and aquatic environments. Methylmercury is a neurotoxin.
When in-use, mercury is safely contained in batteries, fluorescent lightbulb filaments and other consumer goods. However, people must be sure not to dispose of these products in the trash.
If contaminated waste is disposed of in the trash, it will go to a landfill, where the mercury either gets into groundwater, or is incinerated, goes into the air and then eventually gets into water. Instead, bring these products to local household hazardous waste programs for disposal.