Methods for Measuring the Toxicity and Bioaccumulation of Sediment-Associated Contaminants With Freshwater Invertebrates-Second Edition

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Notice of availability of methods for measuring the toxicity and bioaccumulation of sediment-associated contaminants with freshwater invertebrates—second edition.

SUMMARY:

The Environmental Protection Agency (EPA) is publishing procedures for testing freshwater organisms in the laboratory to evaluate the potential toxicity or bioaccumulation of chemicals in whole sediments. This second edition updates methods originally published in 1994 (EPA/600/6-94/024). The second edition of the manual includes new methods for evaluating sublethal effects of sediment-associated contaminants utilizing long-term sediment exposures. Procedures are described for testing the freshwater organisms in the laboratory to evaluate the potential toxicity or bioaccumulation of chemicals in whole sediments. Sediments may be collected from the field or spiked with compounds in the laboratory. Toxicity methods are outlined for two (2) organisms, the amphipod Hyalella azteca, and the midge Chironomus tentans. Toxicity tests with amphipods or midges are conducted for 10 days in 300-mL chambers containing 100 mL of sediment and 175 mL of overlying water. Overlying water is renewed daily and test organisms are fed during the toxicity tests. The endpoints in the 10 day test with H. azteca and C. tentans are survival and growth. Procedures are primarily described for testing freshwater sediments; however, estuarine sediments (up to 150/00 salinity) can also be tested in 10 day sediment toxicity tests with H. azteca. Guidance is also provided for conducting long-term sediment toxicity tests with H. azteca and C. tentans. The long-term sediment exposures with H. azteca are started with 7-to 8-day old amphipods. On day 28 of the sediment exposure, amphipods are isolated from the sediment and placed in water-only chambers where reproduction is measured on day 35 and 42. Endpoints measured in the amphipod test include survival (day 28, 35, and 42), growth (on day 28 and 42), and reproduction (number of young/female produced from day 28 to 42). The long-term sediment exposures with C. tentans start with newly hatched larvae (<24 hours old) and continue through emergence, reproduction, and hatching of the F₁ generation (about 60 day sediment exposures). Survival and growth are determined at 20 days. Starting on day 23 to the end of the test, emergence and reproduction of C. tentans are monitored daily. The number of eggs/female is determined for each egg mass, which is incubated for 6 days to determine hatching success. The procedures detailed in this document include measurement of a variety of lethal and sublethal endpoints with Hyalella azteca and Chironomus tentans. Minor modifications of the basic methods can be used in cases where only a subset of these endpoints is of interest. Guidance for conducting 28 day bioaccumulation tests with the oligochaete Lumbriculus variegatus is also provided in the manual. Overlying water is renewed daily and test organisms are not fed during the bioaccumulation tests. Methods are also described for determining bioaccumulation kinetics of different classes of compounds during 28 day exposures with L. variegatus.

This guidance is designed to describe procedures for testing freshwater organisms in the laboratory to evaluate the potential toxicity or bioaccumulation of chemicals in whole sediments. This guidance document has no immediate or regulatory consequence. It does not in itself establish or affect legal rights or obligations, or represent a determination of any party's liability. The USEPA may change this guidance in the future.

This guidance document has been reviewed in accordance with USEPA Policy and approved for publication. Any mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Availability of Document: Copies of the complete document, titled Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates—Second Edition (EPA/600/R-99/064) can be obtained from the National Service Center for Environmental Publications, P.O. Box 42419, Cincinnati, OH., 45242 by phone at 1-800-490-9198 or on their web site at www.epa.gov/ncepihom/orderpub.html. A pdf version of this document will be made available to be viewed or downloaded from the Office of Science and Technology's home page on the Internet at www.epa.gov/OST/.

FOR FURTHER INFORMATION CONTACT:

D. Scott Ireland, USEPA, Standards and Applied Science Division (4305), Office of Science and Technology, Ariel Rios Building, 1200 Pennsylvania Avenue, N.W., Washington, DC 20460; or call (202) 260-6091; fax (202) 260-9830; or e-mail ireland.scott@epa.gov.

SUPPLEMENTARY INFORMATION:

Background Information

Sediment contamination is a widespread environmental problem that can potentially pose a threat to a variety of aquatic ecosystems. Sediment functions as a reservoir for common chemicals such as pesticides, herbicides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and metals such as lead, mercury, and arsenic.

These methods provide consistent testing protocols for agency-wide use to evaluate risks and provide comparable data. They provide the basis for uniform cross-program decision making within the USEPA. Each program, however, retains the flexibility of deciding whether identified risk would trigger regulatory actions.