United States       Prevention, Pesticides     EPA712-C-96-322
          Environmental Protection    and Toxic Substances     February 1996
          Agency         (7101)
&EPA    Microbial Pesticide
           Test Guidelines
           OPPTS 885.3550
           Acute Toxicity, Tier

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                           INTRODUCTION
     This guideline is one  of a  series  of test  guidelines that have been
developed by the Office of Prevention, Pesticides and Toxic Substances,
United States Environmental  Protection Agency for use  in the testing of
pesticides and toxic substances, and the  development of test data that must
be submitted to the Agency  for review under Federal regulations.

     The Office of Prevention, Pesticides and Toxic Substances (OPPTS)
has  developed this guideline through  a process of harmonization that
blended the testing  guidance  and requirements that  existed in the Office
of Pollution Prevention and  Toxics  (OPPT) and appeared in Title  40,
Chapter I,  Subchapter R of the Code of Federal Regulations  (CFR),  the
Office of Pesticide Programs (OPP) which appeared in publications of the
National Technical  Information Service (NTIS) and the guidelines pub-
lished by the Organization  for Economic Cooperation and Development
(OECD).

     The purpose of harmonizing these  guidelines  into a single set of
OPPTS guidelines is to minimize  variations among the testing procedures
that must be performed to meet the data  requirements of the U. S. Environ-
mental Protection Agency  under  the Toxic  Substances  Control Act  (15
U.S.C. 2601) and the Federal Insecticide, Fungicide and Rodenticide Act
(7U.S.C. I36,etseq.).

     Final  Guideline Release: This guideline  is available from the U.S.
Government Printing Office, Washington, DC 20402 on The Federal Bul-
letin   Board.   By  modem  dial   202-512-1387,  telnet   and   ftp:
fedbbs.access.gpo.gov    (IP     162.140.64.19),    internet:     http://
fedbbs.access.gpo.gov, or call 202-512-0132 for disks  or paper copies.
This guideline is also available electronically in ASCII and PDF (portable
document format) from the EPA Public Access Gopher  (gopher.epa.gov)
under the heading "Environmental Test  Methods and Guidelines."

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OPPTS 885.3550 Acute toxicity, Tier II.
     (a) Scope—(1) Applicability. This guideline is intended to meet test-
ing requirements of the Federal  Insecticide, Fungicide,  and Rodenticide
Act (FIFRA) (7 U.S.C. 136, et seq.).

     (2) Background. The source material used in developing this har-
monized OPPTS test guideline is the OPP guideline 152A-20.

     (b) Purpose. Acute toxicity data provide information on health haz-
ards likely to arise from a single exposure to toxins or toxic components
derived from or associated with the test substance. The toxic components
are to  be  isolated and identified. The purpose  of an acute toxicity study
is to determine the median lethal dose, its statistical limits, and slope using
a single exposure and a  14-day postexposure observation period.

     (c) Definitions.  The following definitions apply to this guideline.

     Acute toxicity is the adverse effects occurring from administration of
a single dose of a component, or components, of the test substance.

     Median lethal dose is a statistically derived single dose of a substance
that  can be expected to cause  death in 50 percent  of animals. It is ex-
pressed in terms of weight of test substance per unit weight of test animal,
and  also in terms  of the  proportion, by weight, of toxic components in
the test substance per unit weight of test animal.

     (d) Principle of the test method. The test substance, including toxic
components, is administered in graduated doses  to several groups of exper-
imental animals, one dose being used per  group.  Subsequent observations
of effects and deaths are made. Animals  which die during the test are
necropsied,  and at the  conclusion of the  test,  the surviving animals are
sacrificed and necropsied as  indicated by the nature of  the  toxic effects
observed.

     (e) Substance be tested. Toxic components of the MPCA preparation
are to  be isolated and identified.  The test substance  will comprise an ap-
propriately purified preparation of the toxic  components. The proportion
by weight of toxic components in the test substance is to be determined
and reported.

     (f) Test procedures—(1) Animal selection. The species and strains
of test animal to be  used are those in which toxic effects were observed
in the acute toxicity/pathogenicity studies from Tier I.

     (2) Route of exposure.  The route  or routes of  exposure should cor-
respond to each and all routes (i.e.  oral,  dermal, and pulmonary) where
toxicity was observed in the acute toxicity/pathogenicity studies from Tier
I. A separate acute  toxicity test  is required for  each route  of exposure.

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     (3) Other test standards, (i) The applicable test standards set forth
in OPPTS  885.2500, 885.2550, and  885.2600, and in OPPTS 870.1100,
870.1200, and 870.1300 should be followed.

     (ii)  If acute pulmonary toxicity tests  are  required,  the applicable
standards set forth in OPPTS 885.3150 usually will take precedence over
the standards set forth in OPPTS 870.1300.

     (g) Tier  progression. The Agency  will make recommendations on
appropriate further test requirements. In general,  further test requirements
comprise appropriate tests as described for biochemical pest control agents
in this series of guidelines (OPPTS 885) or for chemical pesticides as de-
scribed in OPPTS series 870.

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