EPA/821/B-00/004
United States
Environmental Protection
Agency
Office of Water
4303
July 2000
Fact Sheet
Method Guidance and Recommendations for
Whole Effluent Toxicity (WET) Testing (40 CFR
Part 136)
Summary
EPA is making available a guidance document titled, "Method Guidance and Recommendations for Whole
Effluent Toxicity (WET) Testing (40 CFR Part 136)." This guidance document provides additional clarification
regarding suggestions and recommendations in WET test methods that are incorporated by reference at 40 CFR
Part 136 for use in monitoring under the National Pollutant Discharge Elimination System (NPDES) permitting
program.
Background
On October 26, 1995, the U.S. Environmental
Protection Agency (EPA) approved 17 whole
effluent toxicity (WET) test methods for use in
monitoring under the NPDES permitting
program. These WET test methods measure
the aggregate acute and chronic toxic effects of
an effluent using standardized freshwater,
marine, and estuarine plants, invertebrates, and
vertebrates. EPA developed this document,
Method Guidance and Recommendations for
Whole Effluent Toxicity (WET) Testing (40 CFR
Part 136), to clarify and update specific
recommendations and suggestions on technical
aspects of the WET methods. EPA prepared
these updates and clarifications as part of an
effort to resolve litigation challenging the
October 1995 rulemaking.
Summary of Guidance Document
The new guidance document is designed to
provide EPA Regional, State, Tribal, and local
authorities; regulated entities; and
environmental laboratories with additional
guidance regarding the conduct of WET tests
and interpretation of WET test results. The
guidance document addresses the following five
specific technical issues.
« Nominal error rate adjustments - When can
the nominal error rate used in WET testing be
reduced from 0.05 to 0.01?
° Confidence intervals - When are confidence
intervals not generated by point estimation
techniques?
• Concentration-response relationships -
How can the concentration-response
relationship concept be used in a test review
step to validate WET test results?
• Dilution series selection - How can dilution
series selection be used to assist in
determining a concentration-response
relationship and improve endpoint precision?
» Dilution waters - What does EPA consider
to be an acceptable dilution water?
Additional Information and Copies
For further information concerning this guidance
document, please contact Ms. Marion Kelly at
the U.S. Environmental Protection Agency,
Office of Water, Engineering and Analysis
Division (4303), 1200 Pennsylvania Avenue,
NW, Ariel Rios Building, Washington, D.C.
20460 (e-mail: kelly.marion@epa.gov); or John
Fox at the U.S. Environmental Protection
Agency, Office of Water, Engineering and
Analysis Division (4303), 1200 Pennsylvania
Avenue, NW, Ariel Rios Building, Washington,
D.C. 20460 (e-mail: fox.john@epa.gov).
The complete text of the Federal Register notice
of availability and a pdf version of the guidance
document may be viewed or downloaded on the
Internet at http://www.epa.gov/OST/WET.
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Laboratory name:
Laboratory ICR ID (if applicable):
Hemacytometer Data Sheet for Cryptosporidium Giardia (Circle One)
Source of stock suspension:
Date of hemacytometer counts:
Date stock suspension received:
Analyst performing counts:
Preparation being counted:
Count
number
1
2
3
4
5
6
7
8
9
10
Number of
oocysts/cysts counted
Number of mm2
counted
Dilution factor
Number of oocvsts/cvsts
mL
Remarks
-
Additional comments:
July 16,1998, Revision - Draft
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Laboratory name:
Laboratory !CR ID (if applicable):
Method 1622 Spiking Suspension Enumeration Form: Cryptosporidium Giardia (Circle One)
Internal spiking suspension enumeration ID number (note on Line 7 of bench sheet)
Source of stock Cryptosporidium oocyst/ Giardia cyst suspension
Stock Cryptosporidium oocyst/ Giardia cyst suspension lot number
Date that stock Cryptosporidium oocyst/ Giardia cyst suspension was received
Date of this spiking suspension enumeration
Analyst performing enumeration
Well number (or hemacytometer chamber number if not using well-slide enumeration)
1
2
3
4
5
6
7
8
9
10
Oocysts/cysts counted
Time enumeration completed (samples must be spiked within 24 hours of enumeration)
Mean of the 10 counts
Standard deviation of the 10 counts
Relative standard deviation
Volume used per well (in /A.)
Comments:
July 16,1998, Revision - Draft
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EPA/821/B-00/004
Method guidance and
recommendations for whole
effluent toxicity testing
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