United States      Prevention, Pesticides     EPA712-C-96-186
          Environmental Protection   and Toxic Substances     August 1996
          Agency        (7101)
&EPA    Residue Chemistry
          Test Guidelines
          OPPTS 860.1550
          Proposed Tolerances

     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

     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,    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."

OPPTS  860.1550 Proposed tolerances.
     (a) Scope—(1) Applicability. This guideline is intended to meet test-
ing  requirements  of  both  the  Federal  Insecticide,  Fungicide,  and
Rodenticide Act (FIFRA) (7 U.S.C.  136, et seq.)  and the Federal Food,
Drug, and Cosmetic Act (21 U.S.C. 301, et seq.}

     (2) Background. The source materials used in developing this har-
monized OPPTS guideline are OPP 171-6 Proposed Tolerances, OPP 171-
8 Exemptions from the Requirement of a Tolerance, and OPP  171-9 Toler-
ance for Foreign Uses  (Pesticide Assessment Guidelines, Subdivision O:
Residue Chemistry,  EPA  Report 540/9-82-023, October  1982). This
OPPTS guideline  should be used in  conjunction with OPPTS  860.1000

     (b) General—(1) Determining the tolerance level. To obtain a toler-
ance, the petitioner proposes a tolerance level,  based on residue field trial
data, which reflects the maximum residue  that may occur under  worst-
case conditions as  a result of the proposed use of the pesticide. The toler-
ance must include significant metabolites  of toxicological  concern and
must be high enough to  cover all components of the total toxic  residue
(TTR). The pesticide active ingredient and any significant metabolites  to-
gether  comprise the TTR. If one component of the residue is significantly
more toxic than other components, two levels may be included in the toler-
ance expression.

     (2) Significant metabolites of concern and  tolerance expression.
(i) Using the results of plant and animal metabolism studies, EPA deter-
mines  which metabolites are of concern and need to  be included in  the
tolerance expression. In each case, this  decision is based on the toxicity
of the  metabolite and the magnitude  of its residue. Metabolites that  are
toxicologically significant and occur at significant levels require a suitable
analytical method.

     (ii) In some cases, tolerances may be based on only a portion of  the
residue of concern  in order to ease enforcement or to harmonize with inter-
national tolerances. This may be referred to as an indicator compound,
which  typically would be the parent pesticide. However, residue data  are
still  required on all residues of concern so the latter  can be included in
dietary risk assessment.

     (c) Proposed  tolerances—section  F of a petition). (1) Tolerances
should be  proposed in terms that best represent the TTRs on the raw agri-
cultural commodity, whether it be the parent  pesticide,  altered forms of
it, or both. The proposed tolerance should not be based on an average
residue value but  should be large enough to include  any residue  values
that could be reasonably expected based on the available data.

     (2) The tolerance should not be larger than is needed for  the proposed
use although some limited accommodation  to this  rule may be  necessary

in the  interest of avoiding an inordinate multiplicity of tolerance levels
for a single pesticide on a number of different crops. When the analytical
method is based on measurement  of a common chemical moiety, it will
usually determine one or more conversion products along with the parent
compound. In such cases, it  may  be appropriate to propose  a combined
tolerance for all of the compounds calculated as the  parent  compound,
toxicological considerations permitting.

    (3) The petitioner should consider whether the proposed tolerance can
be made compatible with maximum residue limits (MRLs) established by
the Codex Alimentarius Commission (an organization set up under the aus-
pices of the United Nations to facilitate international trade) or the toler-
ances established by Mexico or Canada. The tolerance comparison should
include compatibility of the numerical  level proposed, the residue defini-
tion (i.e. the metabolites included in the tolerance), and the  commodity

    (4) An exemption from  the requirement of a tolerance may also be
proposed when appropriate (see paragraph  (d) of this guideline). When
an exemption is proposed, data should be presented to show the level of
residues to be expected.

    (5) In the case of food additive regulations covering the  use of pes-
ticides in food handling establishments, it is contemplated that the regula-
tion may or may not include a  numerical  tolerance on foods. However,
a numerical indication of the expected residue levels is preferred. In either
case, the proposed regulation should specify the conditions of use of the
pesticide. The determination  of whether a  numerical tolerance is needed
will be based on the toxicity  of the residue and the level of possible con-

    (d) Exemptions from the requirement of a tolerance—(1) Active
ingredients. Exemptions from the requirement of a tolerance are appro-
priate for pesticides for which no  enforcement action can be  anticipated.
Since an exemption from the requirement of a tolerance means that there
is no limit on the level of residue that could occur, exemptions are limited
to relatively non-toxic pesticides. Examples  of active ingredients for which
an exemption is appropriate are  acetic  acid and sulfur. Exemptions from
the requirement of a tolerance for an active  ingredient should be requested
by submission of a petition. Normally,  the  only information/data needed
in such a petition are the data from petition sections A,  B, E, F, and G.
The normal residue chemistry data requirements  in section  D will be
waived for  toxicologically-innocuous  active  ingredients. An analytical
method is rarely needed for enforcement purposes.

    (2) Inert ingredients. Inert ingredients of pesticide formulations have
been determined to be pesticide chemicals within the meaning of the Act
and are subject to the  Pesticide Amendment (section 408) of the FFDC

Act. A large number of these inert ingredients have been exempted from
the requirements of a tolerance (40 CFR 180.1001). Requests to add other
adjuvants should be submitted as petitions for exemption or as a letter
to the Director, Registration Division, Office of Pesticide Programs. Data
requirements for  inerts will not ordinarily be  as extensive as for  active
ingredients.  However, an analytical method may be required and a basis
for estimation of the level of residues likely to result must be provided.
Limitations  on the use may be imposed in the exemption regulation. Any
clearances of the inert ingredient by the FDA as a food or feed additive
should be referenced. The amount of residue chemistry data needed for
the exemption of an inert ingredient will vary with the nature of the chemi-
cal. The  minimum information required are a  description of the identity
of the chemical and the possible uses involved. If the inert ingredient can-
not be deemed toxicologically-innocuous, then additional data will  be re-
quired. In some cases, the full data requirements described for active  ingre-
dient tolerances will be required, while in other cases, only an analytical
method and  residue data  for  representative crops will be required. The
amount of data required will depend on the toxicity of the  chemical and
the use restrictions imposed.

     (e) Tolerances for foreign uses. Foreign uses are not subject to reg-
istration  requirements. However, proposals for tolerances for residues in
any imported foods or feeds should be  submitted under section 408(e) of
the FFDCA.  Tolerances proposed in conjunction with requests for domes-
tic  registration are  submitted  under section 408(d)  of the Act. Petitions
submitted under  section 408(e) should contain the same types of informa-
tion, including sample labelling, and data as those submitted under section