United States Prevention, Pesticides EPA712-C-96-302
Environmental Protection and Toxic Substances February 1996
Agency (7101)
&EPA Microbial Pesticide
Test Guidelines
OPPTS 885.2200
Nature of the Residue in
Plants
-------
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."
-------
OPPTS 885.2200 Nature of the residue in plants.
(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 OPP guideline 153A-6.
(b) When required. Plant metabolism studies are required to deter-
mine the nature of the microbial pest control agent (MPCA) residues in
plants whenever an MPCA use is determined to be a food use. If a use
is likely to result in MPCA residues in or on food, the use is considered
to be a food use. In some cases, however, it may be possible to waive
the requirements for plant metabolism data if no potential MPCA residues
are expected to be of toxicological concern; such a waiver is most likely
to be granted for an indigenous microbe that does not produce or code
for a toxin. Attempts must be made to characterize all MPCA residues
in or on plants regardless of their route of entry and/or deposition or
whether they were produced via metabolic or strictly physicochemical
processes.
(1) Potential residues of concern may be, but are not limited to, the
following:
(i) All types of propagules of the parent (active ingredient) MPCA
such as vegetative cells, sexual and asexual spores, virions, and viroids.
(ii) Mutants of the MPCA in question.
(iii) The genetic material itself.
(iv) Any antigenic/allergenic, toxic, and/or mutagenic substances as-
sociated with the MPCA product either as impurities in the formulation
or as components or metabolic products of the MPCA itself produced dur-
ing the manufacture or storage of the product or at the site of application.
(v) Or any other replicating entity which is the recipient of MPCA
genetic material (chromosomal or extrachromosomal) of potential concern
(such recipients may be viruses or cells of animals, plants, or bacteria).
The genetic stability (ease of genetic exchange or transfer) is thus impor-
tant in determining potential residues of concern, especially in the cases
of nonindigenous or genetically altered MPCAs.
(c) Test procedures and reporting of data. (1) The uptake, metabo-
lism, and translocation of the MPCA must be determined, typically in a
representative member of each crop group defined in 40 CFR 180.34(f)
except the herbs and spices group. If the metabolism is similar in three
unrelated crops, additional crops normally need not be included. In the
case of demonstrated or potential plant pathogens, however, more exten-
sive testing may be required, especially since replication of the MPCA
-------
may occur in nontarget crop species; consultation with appropriate Agency
scientists should be sought if a petition involves a plant pathogen. If pos-
sible, treated plants must be grown to normal crop maturity so that residues
may be characterized in or on the raw agricultural commodities (RACs)
derived from the crop in question.
(2) Plants must be treated via the proposed route (seed treatment, soil
treatment, foliar plus soil treatment, etc). Since intentionally added inert
ingredients could significantly influence MPCA deposition, viability/stabil-
ity, absorption, and even replication at the treatment site, the test substance
should be a typical end-use product (EP). In some cases, radiolabeling
of the MPCA may be useful but, generally, other approaches must be em-
ployed to determine the total terminal residue and, subsequently, which
terminal residues are of toxicological concern (refer to OPPTS 885.3050
through 885.3650). The application rate should be the maximum proposed
rate or exaggerated rates, if necessary for residue identification.
(3) MPCAs, being much more complex than conventional chemical
pesticides, create unusual analytical problems. For example, the total ter-
minal residue may consist of drastically different entities (whole microbes,
toxins, etc.) each requiring greatly differing analytical procedures. Also,
since all or most MPCAs are replicating entities, the total terminal residue
will frequently increase with time but not as a function of continued resi-
due absorption and/or transformation of one residue to another as is typi-
cally the case with conventional pesticides. In some cases, the viable
MPCA per se may not be of toxicological concern but a toxin produced
by the MPCA may be of concern. Note, however, that the MPCA itself
will be regulated even if it serves only as a source of a residue of toxi-
cological concern.
(4) Some MPCAs may remain in the soil and/or on aerial plant parts
whereas others may gain entrance into plants via active or passive routes.
Once in the plant, the MPCA may be transported to other plant parts,
may replicate, and may cause disease; in other cases, replication may occur
only at the site of entrance. Replication may occur only in arthropod or
other hosts in or on plant tissues. In some cases, the MPCA may be re-
stricted to the soil or an isolated plant part, perhaps not a RAC, but exert
its influence throughout the plant such as in the case of a translocatable
toxin. MPCA residues may fluctuate with the growth cycles. It is the re-
sponsibility of the petitioner to demonstrate which, if any, plant parts bear
which residues of concern, i.e. to determine the distribution of residues.
These studies will demonstrate which are the major residues to be sought
in field residue studies, if required, and also will provide an indication
as to the efficiency and sensitivity of the methods used. Refer to OPPTS
885.2300 and 885.2350 for a discussion of some analytical methods ex-
pected to be of use for MPCA determination.
------- |