United States
 Environmental Protection
 Environmental Research
 Duluth MN 55804
 Research and Development
 EPA-600/S3-81-005 Apr. 1981
Project  Summary
 Intel-laboratory  Comparison
 Acute  Testing  Set
Armond E. Lemke
  A multiple laboratory (6) set of tests
was  conducted  using a single Test
Standard Method. The tests consisted
of  static and  dynamic  aquatic
bioassays with two species of fish and
static tests with Daphnia magna in
duplicate. The extreme values for any
one test were one order of magnitude
while the extremes of the means were
only a factor of 2.
  This Project Summary was  devel-
oped by EPA's Environmental Re-
search  Laboratory,  Duluth, MN
55804,  to announce key findings of
the  research  project that  is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
  The U.S. Environmental Protection
Agency is required as part of the Toxic
Substances  Control  Act  to  make
decisions on the safety of any chemical
before  it can  be  marketed. These
decisions must be  based on various
types of information regarding human,
terrestrial  and/or  aquatic environ-
mental   danger  potential. The  law
requires the potential manufacturers to
provide such information if requested
for cause by EPA. In the area of aquatic
toxicity,  bioassay data  is one of the
useful types of  information that may be

Methods and Materials
  The bioassay literature has a rather
diverse  amount of  data on any one
chemical. In an attempt to reduce this
diversity it was decided to use a required
standard test to produce the  needed
data. Estimations of expected diversity
of such a  standard when used by  a
variety of laboratories was needed.
  To  accomplish  this  a  group  of
contractors (4)  and two experienced
EPA  labs  conducted  a  series  of
bioassays with  two  chemicals
(endosulfan and  AgNOa),  and two
species  of fish,  fathead  minnows
(Pimephales promelas)  and  rainbow
trout (Salmo gairdneri) and two types of
acute tests,  static and  dynamic  in
duplicate for  a  test  set of 96 96-hr
LC50s. The same laboratories also
conducted  duplicate  48-hour  acute
static tests with Daphnia magna with
both chemicals for a total of 24 tests.
The chemicals and test protocol were
the same  for all laboratories. Each
provided their own water, test animals,
and chemical analytical support.

  The data set obtained revealed the
following: An extreme value within any
one test of one order of magnitude with
the  organic  endosulfan tests.  The
means  of  the  two  duplicate tests
between all laboratories was just over
two times.
  The silver results were approximately
the same with  the exception  of one
laboratory which had very hard (300 mg
CaCOa/l) water and , as expected, this
value was  much higher. The species
difference was very large. The daphnia
were approximately  10 times more
Sensitive to the silver and 200 times less
sensitive  to  the  endosulfan.  Fish
species difference was only about three

     The   following  conclusions  were
   drawn. If a standard protocol is followed
   closely  and a  material  is not water
   quality dependent, a very precise set of
   data  can  be  expected. Species
   sensitivity is highly variable and species
   from widely diverse groups  should be
   tested. The mean of repeated tests (at
   least two) apparently gives a number of
   sufficient  precision  that  can  be
   reproduced with confidence  Extreme
   care  should   be  exercised   in  all
   extrapolations  especially between
   diverse genetic groups.
            This Project Summary was authored by Armond E. Lemke, who was also the
              EPA Project Officer (see below).
            The complete report, entitled "Interlaboratory Comparison: Acute Testing Set,"
              (Order No. PB 81-160 772; Cost: $6.50, subject to change) will be available
              only from:
                    National Technical Information Service
                    5285 Port Royal Road
                    Springfield,  VA 22161
                    Telephone: 703-487-4650
            The EPA Project Officer can be contacted at:            "
                     Environmental Research Laboratory
                     U.S. Environmental Protection Agency
                     6201 Congdon Blvd.
                     Duluth, MN 55804
                                                                                            tr US. GOVERNMENT HUNTING OFFICE 1M1-757-012/7028
United States
Environmental Protection
Center for Environmental Research
Cincinnati OH 45268
Postage and
Fees Paid
EPA 335
Official Business
Penalty for Private Use $300
                          U  S    90QJOQ