Toxic Pollutants and Chemicals of Concern

Much of Baykeeper’s work focuses on strengthening or maintaining clean water laws and regulations related to toxic pollutants and other contaminants capable of compromising the health of San Francisco Bay. We do this work by engaging in policy and regulatory processes, as well as conducting outreach, research and education. When necessary, we litigate on behalf of clean water and the laws intended to protect it.

Since passage of the Clean Water Act in 1972, scientists and regulators have identified a number of pollutants considered harmful and worthy of strategies intended to reduce their presence in the Bay. Some of these include:

  • Heavy metals, such as copper, mercury and nickel
  • Pesticides, including chlordane, dieldrin, diazinon, DDT and pyrethroids
  • Pathogens from human and wildlife sources
  • Persistent organic pollutants - notably PCBs, dioxins and furans
  • Trash from storm water and land-based sources
  • Other contaminants like cyanide, selenium and various pharmaceutical products

Since our establishment in 1989, Baykeeper has been actively engaged in developing control strategies for much of these pollutants. This article explains our on-going efforts to regulate direct pesticide application to waterways. Read more to learn about our work to improve a regulatory tool intended to reduce mercury in the Bay.

San Francisco Bay’s Legacy of Pollution

In the years following implementation of the Clean Water Act, toxic pollutants were significantly reduced by regulating point source discharges, such as those from industrial polluters and sewage treatment plants that discharge directly to the Bay. These efforts reduced inputs of key contaminants such as nutrients, copper and nickel. Some of the most harmful pollutants found in San Francisco Bay, however, are the result of past practices, such as the use of elemental mercury in gold mining processes during the Gold Rush era.

Contaminants present in the environment today due to activities of the past are known as legacy pollutants, which pose a significant problem to the Bay due to their toxicity and persistence in the environment. Scientists now consider the most significant legacy pollutants found in the Bay to include mercury and PCBs, which are found in relatively high concentrations in Bay sediments and are the principal cause of fish consumption advisories throughout the San Francisco Estuary. Restoration of the Bay as a thriving fishery relies in part on our ability to remove these contaminants or, at a minimum, significantly reduce ongoing inputs so the ecosystem can slowly remove these pollutants through chemical transformations or by flushing contaminated sediments from the estuary.

New and Emerging Contaminants of Concern

Regulators and scientists have long known about the presence and toxicity of legacy pollutants like PCBs and mercury, yet are just now becoming aware of the fact that numerous potentially harmful chemicals are entering the environment – of which we know very little about. Such contaminants are known as contaminants of emerging concern, or CECs, and include a range of chemicals generally found in consumer products, pharmaceuticals and personal care products. CECs can be broadly defined as any synthetic or naturally occurring chemical that is not commonly monitored in the environment but has the potential to enter the environment and cause adverse ecological or human health effects. These pollutants enter waterways primarily via stormwater and wastewater treatment plants, which are not designed to treat and remove the chemicals that make their way down the drain.

Currently, only 91 contaminants are regulated by the Safe Drinking Water Act, while approximately 100,000 chemicals have been registered or approved for use in the United States over the last 30 years. Over the last ten years there has been a failure to add any new chemicals to the Safe Drinking Water Act – a fact that has raised increasing alarm over inadequate regulations surrounding the approval of new chemicals and the potential risk of retaining thousands of potential contaminants within common pharmaceuticals, food and consumer goods.

Local researchers, notably those from the San Francisco Estuary Institute (SFEI), have begun investigating a number of CECs. According to SFEI, there are approximately 100,000 chemicals listed in the US EPA Toxic Substances Control Act inventory, including ~82,000 industrial chemicals, ~8,600 food additives, ~3,400 cosmetics ingredients, ~1,000 active pesticide ingredients, and over 3,000 pharmaceuticals. Despite the high volume and large number of chemicals in use, only a very small portion of these are routinely monitored in the environment. In response, water quality programs at the regional (i.e. Regional Monitoring Program for Water Quality in the San Francisco Estuary, or RMP), state (e.g., for fish consumption advisories), and federal level (e.g., NOAA Mussel Watch) have begun to incorporate some of these chemicals into their monitoring efforts as a proactive measure to identify chemicals that potentially threaten the health of wildlife and humans.

Preliminary data from San Francisco Bay suggests that contaminants such as flame retardants and pharmaceutical products are found in higher concentration in the South Bay, where tidal flushing is lower and wastewater treatment plants represent a high percentage of total freshwater inflow. This preliminary monitoring is a first step towards gaining more information on the current extent of CEC exposure in aquatic environments and can be used to guide further monitoring and management actions.

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