Persistent Toxic Chemicals of Human Health Concern in Fish from San Francisco Bay and the Sacramento River, CA

Inroduction

As a result of a 1994 San Francisco Bay Regional Water Board study, the Office of Environmental Health Hazard Assessment issued an interim health advisory for people consuming fish from San Francisco Bay. This interim advisory remains in effect. In 1997 the Regional Monitoring Program for Trace Substances in the San Francisco Estuary (RMP) and the Sacramento River Watershed Program (SRWP) began monitoring fish contamination in the Bay and on the Sacramento River (River). In 1998 sampling was performed for a one-time study of fish tissue contamination in the Delta, funded primarily through the Deltakeeper. Data from these three efforts can be pieced together to provide a broad overview of fish tissue contamination in much of the watershed of the San Francisco Estuary.

The primary objectives of all three of these efforts have been:

1) to determine whether persistent toxic chemicals occur in fish that are being used as human food at concentrations of potential human health concern, and

2) to provide data that are useful in tracking long-term trends and evaluating the effectiveness of management efforts to improve water quality.

Sampling Design: San Francisco Bay

• Regional Monitoring Program
• Most recent sampling in 1997
• Seven popular species:
  • striped bass,
  • California halibut,
  • leopard shark,
  • white sturgeon,
  • white croaker,
  • shiner surfperch, and
  • jacksmelt
• Seven popular fishing locations throughout the Bay (Figure 1)
• Sampling every three years
• Mercury, PCBs, dioxins, and organochlorine pesticides
• Includes replication and special studies
• Data available from 1994 and 1997

Conclusion: San Francisco Bay

• Concentrations of mercury, PCBs, DDT, chlordane, dieldrin, and dioxins exceeded screening values, indicating potential health concerns for Bay fishers
• Fish from Oakland Harbor had elevated concentrations of mercury, PCBs, DDT, chlordane, and dieldrin
• Mercury concentrations in 1997 were not significantly different from concentrations in 1994. Lipid-weight concentrations of PCBs, DDT, chlordane, dieldrin, and dioxins were lower in 1997 than in 1994. Continued monitoring will be required to establish whether the apparent decreases observed are indicative of long-term trends or short-term fluctuations due to other processes
• No change in consumption advice for halibut, leopard shark, shiner surfperch, striped bass, white croaker, and white sturgeon
• Jacksmelt findings are being evaluated: PCB concentrations may be of concern
• Substantially lower concentrations of trace organics were measured in white croaker fillets with the skin removed. Concentrations of PCBs, DDTs, chlordanes, dieldrin, and dioxin ITEQs were reduced by 30- 50%

Sampling Design: Sacramento River

• Sacramento River Watershed Program Agreement X 999610-01-0 with U.S. EPA
• Sampling began in 1997
• Main focus on two popular species: white catfish and largemouth bass
• 13 fishing locations from Shasta Lake to northern Delta (Figure 5)
• Mercury, PCBs, and organochlorine pesticides - Minimal replication - Data from 1997

Sampling Design: Delta

• Delta Fish Study
• Funds from Deltakeeper and Central Valley Regional Water Quality Control Board
• One time study in 1998
• Two popular species: white catfish and largemouth bass
• 18 fishing locations, including locations on the San Joaquin River south of the Delta (Figure 6)
• Mercury, selenium, arsenic, PCBs, and organochlorine pesticides
• Minimal replication
• PRELIMINARY data from 1998, mercury only

Conclusions: Delta and River

• Mercury concentrations in white catfish are similar to those for which advice was issued in the Bay
• PCB concentrations in rainbow trout and white catfish are at the low end of the range observed for Bay fish
• Need more samples for evaluating need for consumption advice

Related Document: (file size = 770k)

Contaminant Concentrations in Fish from San Francisco Bay 1997, May 1999

> get PDF reader <