EPA Method 100.5

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EPA Method 100.5:
Life Cycle Test for Measuring the Effects of Sediment-associated Contaminants on Midge (Chironomus tentans). Official Name: EPA Test Method 100.5: Life Cycle Test for Measuring the Effects of Sediment-associated Contaminants on Chironomus tentans

C. tentans are cultured for use in testing. One day prior to test initiation the test sediment is homogenized and placed in test chambers. At test initiation 12 larvae are added to each replicate Overlying water is renewed twice daily and each rep is fed once daily (1.5ml) throughout the test. On day 20 of the test 4 reps from each treatment are sieved to recover larvae for growth and survival determinations. Emergence traps are then installed on the remaining reps. Emergence and reproduction are then monitored until day 40. If no additional emergence is recorded for a period of 7d after day 21, then the test can be ended.

The objective of a sediment toxicity test is to determine whether chemicals in sediment are harmful to or are bioaccumulated by benthic organisms. The tests can be used to measure interactive toxic effects of complex chemical mixtures in sediment. Furthermore, knowledge of specific pathways of interactions among sediments and test organisms is not necessary to conduct the tests. Sediment tests can be used to (1) determine the relationship between toxic effects and bioavailability; (2) investigate interactions among chemicals; (3) compare the sensitivitiesof different organisms; (4) determine spatial and temporal distribution of contamination; (5) evaluate dredged material; (6) measure toxicity as part of product licensing or safety testing or chemical approval; (7) rank areas of cleanup, and (8) set cleanup goals and estimate the effectiveness of remediation or management practices.

Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates, Second Edition, March 2000. EPA 600/R-99/064.

There are three categories of interfering factors that can cause false-negative or false positive responses: (1) those characteristics affecting survival independent of chemical concentration (Ex: UV exposure, grain size), (2) changes in chemical bioavailability as a function of sediment manipulation or storage, and (3) the presence of indigenous organisms.

QC Requirements:
Acceptable water, test conditions, organisms. Reference toxicant testing. Performance-based criteria specifications must be met.

Maximum Holding Time:
8 weeks.


Chronic Toxicity


Sample Prep:

Test precision is estimated by reference toxicant testing. Intra- and Inter-laboratory precision are described by the mean, standard deviation, and relative standard deviation (percent coefficient of variation, or CV) of the calculated endpoints from the replicated tests.


Revision Number:
Second Edition, March 2000