PB85-120962
Pesticide Assessment Guidelines Subdivision K, Exposure: Reentry
Protection
(U.S.) Environmental Protection Agency
Washington, D.C.
5 Oct 84
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,'l iPORT DOCUMENTATION
PACE
Pesticide Assessment Guidelines 4
Subdivision K^-^ Exposure: Reentry Protection
USEPA, Office, of Pesticide Programs
Hazard Evaluation Division (TS-769)
401 M. St. sw wa<;h. nr
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This publication, Subdivision K of the Guidelines for Pesticide
Registration, is intended to support 40 CFR 158 requirements
for data for the registration of pesticides. Subdivision K,
Exposure: Reentry Protection, addresses means for protecting
agricultural workers from potential hazards of pesticide residues
in previously treated fields. The primary goal is the
. establishment of reentry intervals for those pesticides whose
toxicological properties and use-patterns indicate a high
'potential for field-worker hazard. Criteria for data requirements
. ••„. under 40 CFR 158.140 are listed, and alternatives to reentry
/.- intervals are provided.
available
UNCLASSIFIED
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EPA 540/9-84-001
5 October 1984
PESTICIDE ASSESSMENT GUIDELINES
SUBDIVISION K
EXPOSURE: REENTRY PROTECTION
by
James D. Adams, PhD
Hazard Evaluation Division
Office of Pesticide Programs
U.S. Environmental Protection Agency
Office of Pesticide and Toxic Substances
Washington, D.C. 20460
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SUBDIVISION K — EXPOSURE: REENTRY PROTECTION
TABLE OF CONTENTS
DISCUSSION
I. BACKGROUND: REENTRY PROTECTION CONSIDERATIONS 1
II. ORGANIZATION AND PHILOSOPHY OF SUBDIVISION K 4
A. "When Required" Paragraphs 5
B. References to Published Literature 6
III. DISCUSSION OF INDIVIDUAL DATA REQUIREMENTS 6
A. General Provisions 6
1. When Required 6
2. Toxicity criteria 6
3. Use type 7
B. Toxicity Data 9
C. Residue Dissipation Data 11
D. Human Exposure Monitoring Data 12
E. Calculation of Reentry Levels and Reentry Intervals 15
1. Non-Detectable Residue Method 15
2. Allowable Exposure Level (AEL) 15
3. Adjustment to Reentry Intervals 16
4. Early Reentry 17
IV. REFERENCES CITED IN DISCUSSION 17
GUIDELINES
Series 130: GENERAL PROVISIONS 19
130-1 Basic guidance 19
130-2 Definitions 21
130-3 Requirement for reentry interval and supporting data 24
130-4 General reporting requirements 25
130-5 Coordination with requirements of other subparts 26
Series 131: TOXICITY DATA 27
131-1 Data required 27
131-2 Exposure conversions and penetration assumptions 27
131-3 Determining allowable exposure level 28
Series 132: RESIDUE DISSIPATION DATA 29
132-1 Requirements for residue dissipation data 29
132-2 Dissipation of dislodgeable residues 30
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TABLE OF CONTENTS
Series-133: MEASUREMENT OF HUMAN EXPOSURE 33
133-1 Descriptions of human activity 33
133-2 Requirements for exposure data 34
133-3 Measurement of dermal exposure 35
133^4 Measurement of inhalation exposure 42
Series 134: CALCULATION OF REENTRY LEVELS AND REENTRY
INTERVALS 47
134-1 Non-detectable residue method 47
134-2 Allowable exposure level method 48
134-3 Adjustment to reentry intervals 51
134-4 Early reentry: practices and limitations 52
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1
I. BACKGROUND: REENTRY PROTECTION CONSIDERATIONS
Soon after the uses of the highly toxic organic pesticides
became widespread, the public expressed concern that people per-
forming activities at the site of application could be poisoned by
residues of these compounds (cf. Abrams and Leonard, 1950; and
Ingram, 1951). In 1958, Quinby and Lemon reported a number of poi-
soning episodes in which groups of people had become ill during
or soon after harvesting tree fruit crops. T.H. Milby (1971) also
reported a number of worker poisonings. In all of these cases,
the people had been exposed to residues of organophosphorus pesti-
cides and.exhibited symptoms of cholinesterase depression that are
characteristic of organophosphorus poisoning. (For reviews on
this subject, see Gunther et al., 1977; Kilgore et al., 1977; and
Popendorf and Leffingwell, 1982).
In addition, the Agency has gathered similar information on
reentry related poisonings. The information was gathered through
the Agency's Pesticide Incident Monitoring System (PIMS) and from a
series of reports put out by the California Department of Food and
Agriculture. PIMS receives voluntary reports of incidents of
pesticide poisoning. Over 20 percent of the reported incidents
involved 2 or more people. Eighty-four of the reports recorded in
PIMS are considered as reentry-related episodes, and most occurred
in California. Thus, there is probably an overlap with the Cali-
fornia Department of Food and Agriculture reports.
Restriction of reentry has received increasing attention from
the public and the Agency because of the potential for poisoning of
large groups of people. Unfortunately, national estimates of the
number of field reentry poisonings do not exist. However, California,
the Nation's largest agricultural producer, requires physicians to
report worker injury to the State Government. In 1977, the most
recent year for which data are available, a total of 1,518 cases of
occupational illnesses or injuries related to pesticide exposure
were reported. Of these 1,518 cases, 182 were in the field worker
job category. The majority of the cases, 108, were classified as
skin injuries, 50 were systemic illnesses, 21 were eye injuries,
and 3 were eye and skin injuries. The actual number of cases is
thought to be significantly higher because of incomplete reporting
and diagnosing by physicians, and because workers often do not seek
or are unable to obtain treatment from a physician for pesticide
exposures.
Case reports of field reentry poisoning demonstrate that
incidents can be very serious in terms of symptoms and number of
individuals affected, as the following examples illustrate:
Example 1. The largest incident known to the Agency involved
approximately 150 high school age workers who entered a corn
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field in Indiana to detassel corn. The field had been treated
the previous day by helicopter with Carbofuran and Dithane M-45.
Seventy-four of the workers were affected and 29 were hospita-
lized. Major symptoms that occurred in this exposure episode
were dizziness, nausea, blurred vision, and dermal irritation.
Example 2. Thirteen out of a group of 26 adult migratory
workers in eastern Tennessee developed a hypersensitivity to
Dyrene after prolonged work with tomato plants and fruit that
had previously been treated with the pesticide. The tasks
were planting and staking of plants and harvesting of fruit.
Skin patch tests were positive for Dyrene sensitivity for six
of the seven workers tested.
Example 3. A total of 118 workers from a 120-person grape-
picking crew working in a vineyard near Madera, California,
became ill in early September 1976. Of these (108 men and 10
women), 85 received medical attention and three of the 85 were
admitted to the hospital. The symptoms were typical for organo-
phosphate poisoning: average plasma and red cell cholinesterase
values for the affected workers were depressed more than 60
percent. Most were treated with atropine and some were also
treated with 2-PAM (pralidoxime). The workers were exposed to
residues of the organophosphate pesticides dialifor (Torak)
and phosalone (Zolone). It appeared that workers had been
allowed into recently-treated areas before the expiration of
the required 30-day safety interval for dialifor [required by
the California Department of Food and Agriculture], and that
excessive exposure to residues of this pesticide had resulted.
(Details of this incident are reported in the Western Journal
of Medicine 129: 273-277, 1978.)
Example 4. This incident occurred in North Carolina and
involved parathion and maleic hydrazide on tobacco. A 15-year-
old, 127-pound girl began topping three days after application.
Label directions read "Wait 5 days before cutting or harvesting."
The girl became ill shortly after leaving the field in midafter-
noon and was taken to an emergency room that evening where
treatment began at 8:45 p.m. Her symptoms were chest tightness,
confusion, difficult breathing, dilated pupils, fainting,
headache, increased tearing, nausea, nervousness, and vomiting.
Atropine (0.4 mg) was administered periodically. She also
received intravenous support. Two laboratory tests indicated
that cholinesterase activities were below normal.
From the episodes documented in the PIMS and California reports,
the Agency concludes that:
- (1) Reentry into pesticide treated sites can present significant
hazard;
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(2) The problem exists throughout the country although it appears
to be greatest in California; and
(3) Pesticides other than organophosphates can also pose reentry
problems.
A number of factors affect the extent of the reentry hazard.
The most important factors are: the surface and airborne residue
levels of the parent compound and its toxic alteration products; the
amount of these residues transferred to people; the absorbed dose;
and the toxicological response to the absorbed residues. Many
variables have direct impact on these key factors. Residue levels
at a treated site are affected by climate, formulation, rate and
frequency of application, conditions during application, type of
crop, and the length of time since application. The transfer of
residues to people, i.e., human exposure, may be influenced by the
type of human activity (pruning, thinning, etc.), duration and fre-
quency of activity, and the type of clothing worn. The toxicolog-
ical response varies with susceptibility among people. For example,
very old, very young, malnourished, or pregnant workers may be more
sensitive to adverse effects.
Clearly, establishment of precise reentry intervals taking into
account every possible exposure/risk situation in each geographic
area is impractical. Human monitoring studies or scientific
equations cannot reasonably be expected to handle all the signifi-
cant variables outlined above. One practical solution would be to
establish general reentry intervals, which then could be revised
by new data or waived when certain protective mechanisms are used,
as discussed below. The foliar residue dissipation study should be
carried out at a site which is representative of the area where the
pesticide is expected to be used. Criteria for site selection should
include geographical and meterological considerations as well as crop
type. Applicants may wish to consider carrying out additional such
studies at other sites in order to propose separate reentry intervals
for other geographical areas. Applicants should consider discussing
site selection with the Agency before beginning such studies.
Certain pesticides have a potential to cause adverse effects
on the environment or may cause injury to the applicator, even when
applied in accordance with directions for use. Such pesticides are
restricted to use only by certified applicators who have completed
an approved training program. Training programs to certify applica-
tors are designed to ensure that users have the competence to handle
pesticides without endangering humans or the environment.
While Subdivisions F and H and the certified applicator program
are designed in part to protect applicators of pesticides, Subdivi-
sion K and the reentry standards [40 CFR § 170.3(b)] are designed
to protect those individuals reentering sites where pesticides have
recently been applied. A new guidelines Subdivision U is being
written to describe protocols to be used to establish methods for
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the protection of mixers, loaders, applicators, etc. Subdivision K
describes the data needed to develop appropriate label instructions
regarding reentry. Certain of these reentry standards characterize
measures which are not necessarily applicable to product labeling,
but which are important practices designed to protect individuals
returning to potentially hazardous treated sites. These practices
include posted and/or verbal warnings and provision of protective
equipment, washing facilities, and worker education or training,
as well as reentry intervals and reentry levels. To prevent poison-
ing of human beings by residues of some of the most toxic pesticides,
the Agency has established reentry intervals [in 40 CFR § 170.3(b)]
for pesticide products containing any of twelve active ingredients.
Eleven of these active ingredients are organophosphorus insecticides
and the other active ingredient is an organochlorine insecticide.
That section also contains other standards intended for the protect-
ion of farmworkers from the toxic effects of pesticides and pesti-
cide residues.
In the past, the EPA has repeatedly indicated its interest in
soliciting comments relevant to determination of reentry intervals
using environmental chemistry and exposure data [see proposed
Guidelines of June 25, 1975 (40 FR 26802) and July 10, 1978 (43 FR
29696]. Subpart F (43 FR 37336), proposed on August 22, 1978,
contained a discussion of exposure data that would be useful for
the establishment of reentry intervals, and invited comments. No
response on this topic was received. In addition, during the past
year the Agency has distributed prepublication drafts of this sub-
division to the public in connection with a review of this subdivi-
sion by the FIFRA Scientific Advisory Panel. The EPA has received
several comments on these drafts. The Agency has considered those
comments and guidance received from the Scientific Advisory Panel
in the development of this subdivision.
Certain states have also established reentry intervals and
other measures for the protection of people from the toxic effects
of pesticide residues. For example, the California Department of
Food and Agriculture (CDFA) has established reentry intervals and
data requirements for pesticide registration in that State. Under
the CDFA regulations, foliar and soil residue data for a pesticide
and any toxic alteration products must be submitted if any of
several toxicology criteria are met. A more detailed discussion
and comparison of the CDFA regulations with these Subdivision K
guidelines is presented in part III(A) of this discussion.
II. ORGANIZATION AND PHILOSOPHY OF SUBDIVISION K
Proposed rule, 40 CFR 158, specifies the kinds of data and
information that must be submitted to EPA to support the registra-
tion of each pesticide under the Federal Insecticide, Fungicide,
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and Rodenticide Act. The Agency intends to promulgate Part 158 as
a final rule during 1984. This subdivision provides information
relating to the data requirements listed in 40 CFR § 158.140 includ-
ing the conditions under which each data requirement is applicable,
standards for acceptable testing, and the information that should
be included in a test report. The purpose of this subdivision is
to provide guidance so that an applicant can determine whether a
reentry interval is required for his product and can develop the
data necessary to make the calculations for the estimation of a
reentry interval and reentry level.
This subdivision is organized into five series of sections.
The first section series (130), General Provisions, sets forth
definitions, basic requirements and guidance that apply to the
other sections of this subdivision. The sections in this series
describe the scope, purpose, and use of reentry intervals; define
specific terms used in the subdivision; describe the criteria under
which reentry intervals and supporting data are required by 40 CFR
158.140; and suggest standards for reporting the data.
The second section series (131), Toxicology Data, deals
specifically with use of toxicity data in setting reentry intervals.
Among other things, it states the assumptions concerning dermal
and inhalation absorption of pesticide residues which should be
used in determining an allowable exposure level, "AEL."
The third section series (132), Residue Dissipation Data,
explains the § 158.140 requirements for data on the dissipation
of dislodgeable and airborne residues; provides procedures for con-
duct of the studies; and suggests standards for reporting the data.
The fourth section series (133), Human Exposure Monitoring
Data, describes needed use practice information; explains exposure
data requirements of § 158.140; provides procedures for measurement
of inhalation and dermal exposure; and suggests standards for
reporting the data.
The last section series (134), Calculation of Reentry Levels
and Intervals, discusses two methods for setting reentry intervals:
the nondetectable residue method, and the allowable exposure level
method. This section also contains provisions describing circum-
stances which may lead to revision of reentry intervals. Finally,
this series discusses limitations for early reentry.
A. "When Required" Paragraphs.
The "When required" paragraphs in this subdivision discuss the
circumstances under which 40 CFR § 158.140 requires specific data.
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When data are required, that data is to support the registration of
the end-use product and each manufacturing-use product used to for-
mulate each end-use product. The data will normally be gathered by
the manufacturer of the manufacturing-use product but using an end-
use product for the tests. That end-use product need not be the
end-use product submitted for registration.
B. References to Published Literature.
Many of the individual sections of this subdivision contain
lists of references as an aid to applicants. These references
contain test protocols or general information useful for the design,
performance, or evaluation of test studies.
III. DISCUSSION OF INDIVIDUAL DATA REQUIREMENTS
A. General Provisions.
1. When Required. Reentry intervals are required by 40 CFR
§ 158.140 only for highly toxic pesticides which have use types
likely to result in high dermal and inhalation exposure to persons
entering pesticide treated fields. The various sections entitled
"when required" discuss the conditions under which specific data
are required by 40 CFR § 158.140, and explain that data are requir-
ed only for those pesticides which meet both toxicity and use type
criteria.
2. Toxicity criteria. The toxicity criteria, under which 40 CFR
§ 158.140 requires a reentry interval and supporting data, are
listed and discussed in § 130-3 of this subdivision. The Agency
requires that registration of pesticides with acute dermal, inhala-
tion, and oral toxicity properties corresponding to Toxicity Cate-
gory I as listed in Subdivision H at § 100-7 should be supported by
the establishment of reentry intervals. These acute toxicity
criteria are as follows:
- (1) LDso: 200 mg/kg or less for dermal toxicity; - (2) LCsg: 200
mg/m or less for inhalation toxicity; and - (3) LDcg: 50 mg/kg or
less for oral toxicity.
The toxicity criteria in this subdivision are based on the
toxicity of the technical pesticide and its toxic alteration
products. This is necessary because persons reentering treated
sites will normally not be exposed to the formulated product or to
its diluted form as applied, but rather to a "weathered" or
environmentally modified and dissipated residue, which no longer
is composed of the same mixture or ratio of components present in
the formulated product.
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The selection of these acute toxicity criteria reflects the
Agency's judgment that acutely hazardous exposure situations are
likely only for the most acutely toxic pesticides. Experience with
numerous episodes of pesticide reentry poisoning (see part I of
this Discussion) substantiates this judgment. The Agency considered
broadening these criteria to include pesticides with toxicological
properties corresponding to Toxicity Category II of Subdivision H,
but rejected' this consideration for the above reason.
The Agency considers that reentry intervals should be required
when an exposure or risk assessment procedure indicates the potential
for adverse chronic effects upon persons entering a treated site.
These adverse effects include neurotoxic, teratogenic, reproductive,
and oncogenic effects, for which the Agency requires toxicology
testing in Subdivision F of the guidelines.
The requirement for reentry intervals to minimize potential
adverse chronic effects reflects the Agency's judgment that chronic
exposures can result from repeated entry into treated sites.
Adverse chronic effects resulting from such exposures are often
subtle and delayed, and therefore not generally brought to the
attention of medical personnel. Indeed, the exposed person may be
unaware of the exposure. However, the Agency has a clear mandate
to protect humans from unreasonable adverse chronic effects of
pesticides. This requirement is also consistent with recent regula-
tory decisions on pesticides based on laboratory animal toxicology
data.
As noted earlier in this Discussion, the California Department
of Food and Agriculture has established registration requirements
relating to reentry exposure considerations. The toxicology criteria
specified by the CDFA regulations are broader than the criteria for
requirement of reentry data specified in 40 CFR 158.140 and discussed
in these guidelines. The CDFA criteria include the following:
- (1) LD5Q less than 2000 mg/kg for dermal toxicity;
- (2) Highly irritating to the skin;
- (3) Is a sensitizer; and
- (4) Involves a potential risk of a chronic health effect.
3. Use type. The use type criteria for determining whether a re-
entry interval will be required are discussed in § 130-3. These
use types are characterized by the high likelihood of dermal or
inhalation exposure of persons who enter sites included in these
classes. Dermal exposure will generally arise from contact with
treated foliar, fruit, or soil surfaces; inhalation exposure will
normally arise from respiration of volatilized pesticide residues
and residues adhering to particulate matter which has become air-
borne.
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The Agency believes that these use types constitute the most
likely conditions for significant human exposure in reentry
situations.
The Agency recognizes that other reentry exposure situations
may occasionally occur that would not meet either the toxicity or
use type criteria but which could potentially result in adverse
acute or chronic effects to persons entering treated sites. In
these cases, the Agency will consider the requirement for reentry
intervals and supporting data on a case-by-case basis. Similarly,
there are likely to be cases where the toxicity and use type cri-
teria are met but exposure is not likely to occur. The Agency has
included in 40 CFR 158 procedures for waiving the reentry interval
requirement in such cases.
The Agency recognizes that all the many details of common
agricultural practices involved in caring for crops combine to
determine the magnitude of exposure to persons entering treated
sites. There is wide geographical variability in these practices,
caused largely by clijnatic factors which influence both pesticide
application schedules and harvest times. Intermittent treatment
of certain crops close to or during harvest time may occasionally
result in difficulties for growers when long reentry intervals are
established for the pesticides being used. The guidelines recog-
nize this possibility, and attempt to provide a number of mecha-
nisms for early reentry, that is, reentry before the established
reentry interval has elapsed. These mechanisms represent, in
essence, changes in specific agricultural practices, such as spray-
ing the crop with water to reduce residues, using protective cloth-
ing when harvesting, reducing the hours per day that harvesting
may take place, or performing analytical tests for pesticide resi-
dues at the site in order to demonstrate that such residues are
below the reentry level. The Agency recognizes that in some cases
the only solution may be to alter in some fashion the common prac-
tices used either to treat or to subsequently tend the crop, and
solicits comments on these or other possible methods of reducing
exposure during harvesting or other agricultural activities in
treated sites.
In earlier drafts of these guidelines, the Agency had pro-
posed that certain interior use types be included in the criteria
of § 130-3. These included fumigations in storage facilities,
greenhouses, and other buildings. At a recent public review of a
prepublication draft of these guidelines, the FIFRA Scientific
Advisory Panel expressed concern over whether these interior use
types extended the original intent of the reentry interval concept
beyond the basic goal of protecting fieldworkers harvesting or
tending crops. (The Panel did, however, make it clear that the
Agency should be concerned about limiting all exposure to pesti-
cides, whether the exposure is to applicators, fieldworkers enter-
ing treated sites, or anyone else who may come in contact with
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pesticides as a result of their use.) The discussion at the meeting
centered on concerns that inclusion of these use types made the
scope of the guidelines too broad, since exposure arising from
interior uses of pesticides is a separate issue. Different routes
and mechanisms of exposure are likely in interior settings, and the
conceptual model proposed to establish reentry levels and intervals
would not be applicable for these settings. The Agency has accord-
ingly decided to limit the scope of the current guidelines to use
types associated with growing crops, and has reserved the inclusion
of criteria dealing with interior use types.
B. Toxicity Data.
No new toxicological studies are required by 40 CFR § 158.140.
The toxicological data needed to estimate reentry intervals will be
derived fron studies required under 40 CFR § 158.135 and described
in Subdivision F: Hazard Evaluation - Human and Domestic Animals.
Toxicity data obtained from studies described by Subdivision F
should be used by the applicant for the purposes of this subdivision
in the following ways:
- (1) The applicant should compare his toxicity data with the
toxicity criteria listed in § 130-3. If the applicant's pesti-
cide does not meet those criteria, no further data will generally
be required under 40 CFR § 158.140. That is, neither reentry
levels nor reentry intervals will generally be required for a
pesticide if it is less toxic than specified in § 130-3.
- (2) If toxicity data and use types show that a reentry level and
reentry interval are required by 40 CFR § 158.140, the applicant
should use the toxicity data to estimate an allowable exposure
level (AEL) unless the applicant elects to use the non-detectable
residue approach.
Estimation of an AEL frcm animal toxicity studies necessi-
tates the use of appropriate safety factors and may necessitate
the use of dermal absorption data. The Agency has in the past
used safety factors ranging from 10 to 2000 for exposure and
risk assessment, depending on the severity of the toxic effect
and on the completeness of the data. The Agency considers that
use of safety factors in the evaluation of reentry hazards is
particularly useful and appropriate.
The model for the estimation of an AEL contained in this
document allows for the use of a dermal penetration factor. The
applicant may assume 100 percent dermal absorption for estimation
of the AEL. Alternatively and at the applicant's option, data
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10
may be submitted to support the use of another dermal absorption
factor. EPA has developed a suggested protocol, available on
request, using rats for measurement of dermal absorption.
However, there are situations where dermal penetration data
would not be appropriate for estimation of an AEL. These situa-
tions include direct estimation of the AEL from dermal toxicity
data. Also, EPA recognizes that a model for calculation of reentry
intervals proposed by the California State Department of Food and
Agriculture uses an animal dermal toxicity protocol that may be
appropriate for estimation of reentry intervals for organophos-
phorus pesticides. When that model is used, dermal absorption
data would be superfluous. The Agency solicits comments on the
use of dermal penetration data and on methodology for determina-
tion of such data.
- (3) The AEL should then be used to estimate and to propose a
reentry level and a reentry interval.
The Agency has considered whether to include dermal irritation
and dermal sensitization in the criteria for requiring reentry inter-
vals and supporting data. Dermal irritation and/or dermal sensit-
ization has often been reported to occur during reentry to treated
fields. At a recent public review of a prepublication draft of the
guidelines, the FIFRA Scientific Advisory Panel expressed a particu-
lar interest in protection from exposure to pesticides which can
cause dermal irritation or dermal sensitization. However, since
neither of these effects are characterized by a dose/response rela-
tionship, the Agency does not believe that the establishment of
reentry intervals, which employs the concept of a dose/response
relationship to determine an allowable exposure level, is an effec-
tive way to deal with health effects which may be manifested at very
low exposure levels in certain sensitive individuals. Therefore,
the Agency intends that in seme cases reentry intervals be estab-
lished using the criteria of § 130-3(a)(1)(v), which allows reentry
intervals to be established on the basis of field experience with
adverse effects such as dermal irritation or sensitization, rather
than using results of animal testing to establish an AEL. The
Agency solicits comments on methodology for the establishment of
reentry intervals or other standards for the protection of workers
with respect to dermal irritation or sensitization or to ocular
irritation.
C. Residue Dissipation Data.
At one time, scientists theorized that the most significant
mode for the transfer of pesticide residues to fieldworkers was
volatilization with subsequent inhalation and perhaps dermal
absorption of the vapors. Now, however, most scientists think
that most fieldworker exposure to pesticides in field situations
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11
is by dermal contact with residues sorbed to particulate matter.
Inhalation exposure to vapor phase and particulate residues also
occurs, but it has been reported to be less than one percent of the
dermal exposure in field situations.
On the assumption that human exposure is almost entirely due to
dermal contact with particulate matter, and to reduce the economic
burden of testing, the requirement for a field dissipation study is
limited to measurement with respect to time of the amount of pesti-
cide residues adhering to particulate matter that could be trans-
ferred to people. Foliar dislodgeable residues adhering to partic-
ulates could cause human exposure during activities in tall crops
such as tree fruits, grape vines, and corn. Tasks involving substan-
tial soil contact may cause exposure to residues on particulates
arising from a combination of foliage and soil. Such tasks include
hand harvesting of potatoes, strawberries, or other low crops.
Data describing the dissipation of pesticide residues from
fine soil material over a period of time will only be required when
reentry activities include tasks involving substantial human contact
with the soil.
The residues to be quantified in the dissipation study include
any alteration product or impurity of the pesticide that meets the
criteria listed in § 130-3. For example, in a dissipation study
for parathion, residue levels of both paraoxon (a toxic alteration
product) and S-ethyl O-ethyl 4-nitrophenyl phosphorothiolate (a
toxic impurity) would have to be measured with respect to time.
Certain formulation types can increase the persistence of a
pesticide's activity and, therefore, the toxic hazard to humans.
Among these formulation types are encapsulated and wettable powder
formulations. Formulation type may also affect the physical process
of transfer of pesticide residues to humans. For example, residues
adhering to a wettable powder would be more easily dislodged by
human activity than residues sorbed directly to the plant surface
from a formulation such as an emulsifiable concentrate. For these
reasons, dissipation studies will be required for each formulation
type that is proposed for registration. However, testing with only
one formulation of an end-use product will be required within each
formulation type (i.e., a "typical end-use product"; see 40 CFR 158.)
The fact that the majority of the reentry worker poisoning
episodes have occurred in California has been attributed to the dry
climate there. It has been suggested that rainfall reduces foliar
residues by washing the residues from leaves. Also, rainfall, dew,
and high humidity may contribute to dissipation of pesticide resi-
dues which are susceptible to hydrolysis. Other environmental
factors, such as temperature and wind, are expected to be important
in the dissipation process on the basis of established principles
of chemical and physical processes. For example, the rate of a
chemical reaction is approximately doubled for every 10°C increase
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12
in temperature, and gaseous diffusion is strongly influenced by
temperature and the speed and quantity of air movement. Since
climate is expected to strongly influence the dissipation of pesti-
cide residues, applicants should perform the dissipation study at
a site representative of the climatic conditions expected in the
intended use areas. The Agency will provide guidance on the choice
of site upon request. At the applicant's option, reentry intervals
could be established for other environmental conditions by conduct-
ing further dissipation studies at other sites, and it may be in the
applicant's interest to propose multiple reentry intervals to deal
with these environmental variations.
D. Human Exposure Monitoring Data.
The Allowable Exposure Level (AEL) method uses estimates of
likely human exposure to determine a pesticide residue level at the
treated site, called the reentry level, which can be expected to
lead to human exposure at or less than the AEL. The reentry level
is thus the basis of the allowable exposure level method. Reentry
intervals will be established by determining the time necessary for
pesticide residue levels at the site to decay to this level. These
relationships are depicted graphically in § 134-2 of this subdivision.
An estimate of human exposure resulting from work activity in
treated sites is thus a central facet of the AEL procedure. The
Agency recognizes the extremely variable nature of human activities
during reentry and the equally variable nature of the exposure pro-
cess. In order to provide a reasonable limitation on the extent of
exposure information needed to support the establishment of reentry
intervals, the Agency will accept a "worst case" exposure assessment:
that is, where the highest rate of pesticide transfer would occur.
Since most known reentry poisoning episodes have occurred during
the harvesting of tree fruit, the Agency will accept that as the
worst case exposure situation.
It is thus possible to propose a reentry interval calculated
by the AEL method of § 134-2 without the necessity of carrying out
any field exposure monitoring studies for a new pesticide. This
is because the exposure estimate can be derived from an existing
correlation between pesticide residue levels at the work site and
the resulting exposure levels. An example of such a correlation
is the one published by Popendorf (1980) for workers harvesting
citrus. The basis for that correlation is discussed in detail
below.
The applicant or other interested parties may, at their option,
propose shorter reentry intervals for previously registered pesti-
cides, based on exposure data demonstrating that exposure during the
performance of reentry tasks with the applicant's pesticide is in
fact less than that predicted by the worst case correlation. Addi-
tional reentry intervals for a registered pesticide could also be
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proposed based on lower site residue levels (as might result frcm
lower pesticide use ratesf more rapid dissipation in a different
geographical area, etc.). In such cases, multiple reentry intervals
could be established. '
The Task Group on Occupational Exposure to Pesticides (1974)
recommended the use of human exposure monitoring studies for setting
safe reentry intervals. The -Agency, however, feels that there is
now sufficient information available to obviate the need for human
exposure studies to set safe reentry intervals. However, under
FIFRA, States are allowed to require studies for pesticides to be
registered in that State. The State of California, which is a major
use area for most registered pesticides, currently requires human
exposure monitoring studies in some cases. A protocol developed by
E. Kahn of the California State Department of Health (1980) outlines
the factors that need to be included when monitoring studies are
conducted. The Agency does not recommend or require these studies,
but will accept data from such studies for review if conduct of the
studies meets or exceeds the standards listed in §§ 133-3 and 133-4
of this guidelines subdivision.
The procedure used by the State of California for establishing
reentry levels and intervals is conceptually similar to the allowable
exposure level method proposed in these guidelines. That is, residue
levels at a site, estimate of exposure of people working at a site,
and toxicity of the residues to which they are exposed are used to
establish reentry levels and intervals.
This subdivision proposes two procedures to obtain the exposure
information necessary to support the establishment of reentry inter-
vals. The first of these is to utilize existing exposure monitoring
data obtained for other pesticides under similar use conditions. The
second procedure is to carry out field monitoring studies of reentry
exposure, using the procedures described in section 133 of this
subdivision. The Agency's perception is that human dermal exposure
in treated sites is predominantly a physical process as opposed
to a chemical process. That is, transfer of pesticide residues to '
humans during reentry activities is governed more by the physical
nature of the residues rather than their chemical properties.
According to this concept, the form in which the pesticide was
applied are of primary importance for the exposure process. For
example, residues from application of formulations, such as wettable
powders or encapsulations, that provide a physical vehicle for the
transfer of residues to skin would present a greater hazard than
those from a totally liquid formulation, such as a diluted emulsifi-
able concentrate, when the total foliar residue quantity was the
same. That is, certain formulation types are expected to cause
higher dislodgeable residue levels than other types. The amount of
dermal exposure resulting from contact with foliar or soil residues
is also a function of the extent and intimacy of that contact.
Thus, under the first procedure mentioned above, the Agency will
accept human exposure monitoring data obtained from a previously
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14
registered pesticide as a reasonable measure of the potential exposure
to a new pesticide. The use of this "surrogate" data to establish a
reentry interval removes the need for human exposure monitoring
studies with new pesticides. This proposal is supported by recent
studies [e.g. Popendorf (1980)] in which correlations are established
between foliar dislodgeable residues and the resulting human dermal
exposure.
The second procedure that might be used to obtain the human expo-
sure information necessary to support the establishment of reentry
intervals by the method of § 134-2 is to carry out new exposure
studies. The Agency emphasizes that registration applicants should
not undertake or authorize human exposure studies that could be
expected to pose hazards to the study participants. Any studies
conducted to obtain human exposure data must not violate FIFRA sec.
12(a)(2)(P), which provides that, "..it shall be unlawful for any
person in any State to use any pesticide in tests on human beings
unless such human beings (i) are fully informed of the nature and
purpose of the test..., and (ii) freely volunteer to participate
in the test". Guidelines for Protection of Human Subjects [45 CFR
46], promulgated by the U. S. .Department of Health, Education, and
Welfare, contain information that should be considered for design
of such studies.
The carrying out of exposure monitoring studies for previously
unregistered pesticides may lead to exposure to unknown hazards.
Applicants proposing registration of new pesticides should therefore
utilize a surrogate correlation, such as that, described above to
propose reentry intervals when they are required by § 158.140. In
order to facilitate the identification and utilization of available
correlations between residue levels and reentry exposure monitoring
data, applicants are encouraged to inquire whether the Agency has
identified any such monitoring data which could be used to estimate
exposure to a new pesticide.
It appears unlikely that very many applications will arise for
registration of new pesticides at new sites, for which reentry
intervals will be required, and for which the applicant elects to
use the method of § 134-2. In those cases that do occur, the
Agency reconmends that human exposure data be derived from an
existing correlation rather than from further human exposure moni-
toring studies.
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E. Calculation of Reentry Levels and Reentry Intervals.
If the toxicity criteria and the use type class (see § 130-3)
indicate that a reentry interval is required by 40 CFR § 158.140,
three methods for proposing the interval are provided:
- The non-detectable residue method;
- The allowable exposure level (AEL) method; and
- The adjusted reentry interval approach.
The reason for the three approaches is the need for practical,
economic means of solving reentry problems that occur in a wide
range of situations.
1. Non-Detectable Residue Method. The non-detectable residue
method (§ 134-1) provides an alternative for the registrant whose
pesticide does not persist on treated surfaces. Using this ap-
proach, the registrant would determine the elapsed time until
pesticide residues decline to a nondetectable level at a proposed
application site and application rate. This time interval then
becomes the reentry interval, and the requirement for submission
of human exposure monitoring data is waived.
2. Allowable Exposure Level (AEL). The basic method of establish-
ing an interval is the allowable exposure level (AEL) method
(§ 134-2). Use of this method makes collection of data on pesticide
toxicology, residue dissipation, and human exposure from activities
at the site necessary. The procedure involves establishment of the
level of residues at a treated site, called the reentry level, to
which humans can be exposed without unreasonable adverse effects.
This in turn makes necessary the use or establishment of a correla-
tion between human exposure and residue levels. The elapsed time
(reentry interval) necessary to reach this level is determined fron
residue dissipation data at the site.
Thus, the steps necessary to propose a reentry interval by
the allowable exposure level method are as follows:
- (1) An allowable exposure level is estimated from the toxicity
data submitted in support of registration. Since the AEL is
based only on the toxicity data, it is the same for all tasks and
sites.
- (2) Then a reentry level is estimated for the task which is likely
to lead to the highest exposure under common use and reentry
practices. This is to be accomplished by use of a correlation
between pesticide residue levels and expected human exposure; an
example of such a correlation is shown in Figure 1 of § 134-2.
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If no exposure data are available to establish such a correlation
for the site and task of interest, the correlation may be estab-
lished by carrying out human exposure monitoring studies with
either the pesticide of interest or other pesticides which are
registered for use at the site of interest.
- (3) The reentry level, in turn, will be used by the applicant
to determine a reentry interval. This is to be accomplished by
carrying out residue dissipation studies conducted on residues
resulting from the end use product at the site. The reentry
interval is determined from the residue decline curve as shown
in Figure 2 of § 134-2.
The Agency thus assumes that the value of the reentry level is
related primarily to the task and the AEL of the pesticide.
Therefore, the applicant would not need to recalculate the reentry
level in order to propose a reentry interval for the same task at
another site.
Iwata et al. (1982) have used this method and the California
Department of Food and Agriculture method for the calculation of
a reentry interval and have reported that the two methods give the
same reentry interval.
3. Adjustment to Reentry Intervals. The adjusted reentry interval
is designed to provide the registrant with optional procedures that
may be followed to develop reentry times that are consistent with
the needs and factors associated with a particular site and use
type.
Three procedures to develop adjusted reentry intervals
(§ 134-3) are available at the applicant's option. With the first
procedure, adjustments based on toxicity data may be possible, if,
for example, original toxicity testing was conducted with solvents.
Additional testing may indicate that the pesticide without solvents
is less toxic than originally determined. Such new toxicity data
may allow a new calculation of the AEL.
A second approach for adjusting reentry intervals may be
possible, if the applicant or other interested parties demonstrates
that different climatic conditions or other factors significantly
affect the dissipation of a pesticide in different regions of the
country. Using this procedure, a reentry level is determined, and
then a residue dissipation study for a particular region is conducted
to determine the interval for the pesticide residues to decline to
the reentry level. This time period would become the reentry
interval for that particular region.
With the third adjustment procedure, data from human exposure
studies may indicate that exposure levels are significantly different
because of widespread changes in agricultural:practices or other
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conditions. In such cases, that data may support an adjusted reentry
level and interval.
t
4. Early Reentry. Certain activities, sucftrsas posting, scouting,
crop sampling, etc., may require early reentryHnto treated sites
before the reentry interval has elapsed. Several practices may be
necessary to protect people who undertake early reentry.
The first practice available to allow early reentry is reduc-
tion of site residues by rainfall or equivalent spray washing of
the crop before reentry of people. Data should be developed to
show that a certain amount of rainfall or water spraying results
in a decline of pesticide residues to the reentry level. This
amount of water would then be stated on the pesticide label, allow-
ing the user of the pesticide to spray treated surfaces to permit
early reentry or allowing reentry immediately after sufficient
rainfall.
A second practice that can allow early reentry involves demon-
stration that personal protective equipment will reduce worker expo-
sure to allowable levels, even if pesticide residues are higher
than the determined reentry level.
A third example of early reentry on a site-by-site basis would
be based on the development of practical and dependable field tests
that could be used to demonstrate that the reentry level of pesti-
cides had been reached on treated surfaces, even if the reentry in-
terval had not elapsed. This procedure envisions the use of simple
chemical tests by qualified persons on samples of foliage or other
treated surfaces to show that the reentry level had been reached.
IV. REFERENCES CITED IN DISCUSSION
(1) Abrams, H.K., and A.R. Leonard. 1950. Toxicology of
organic phosphate insecticides. Calif. Med. 73:183.
(2) Gunther, F.A., and J.D. Gunther (eds.). 1980. Minimizing
occupational exposure to pesticides. Residue Reviews 75.
(3) Gunther, F.A., Y. Iwata, G.E. Carman, and C.A. Smith.
1977. The citrus reentry problem: Research on its causes and effects,
and approaches to its minimization. Residue Reviews 67:1-139.
(4) Ingram, F.R. 1951. Health hazards associated with use
of airplanes for dusting crops with parathion. Am. Industr. Hygiene
Assoc. Quart. 12:165.
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18
(5) Iwata, Yutaka, James B. Knaak, Glenn E. Carman, Margarete
E. Dflsch, and Francis A. Gunther. .1982. Fruit residue data and
worker reentry research for chlorthiophos applied to California
citrus trees. J. Agric. Food Chem. 30^215-222.
- • . '..'^' • '
(6) Kahn, E. 1979. Outline guide :"for performance of field
studies to establish safe reentry intervals for organophosphate
pesticides. Residue Reviews 70:27-43.
(7) Kilgore, W.W., M.Y. Li, R.L. Mull, W. Winterlin, N.
Borhani, J. Kraus, P. Kurtz, N. Akesson, and W. Yates. 1977.
Human physiological effects of organophosphorus pesticides in a
normal agricultural field labor population. A preliminary report.
II. Scientific aspects. Food Protection and Toxicology Center,
University of California, Davis, CA.
(8) Milby, T.H. 1971. Prevention and management of
organosphosphate poisoning. J. Am. Med. Assoc. 216:2131.
(9) Quinby, G.E., and A.B. Lemon. 1958. Parathion
residues as a cause of poisoning in crop workers. J. Am. Med.
Assoc. 166:740.
(10) Popendorf, W. 1980. Exploring citrus harvesters'
exposure to pesticide contaminated foliar dust. Am. Industr.
Hygiene Assoc. J. 41:652-659.
(11) Popendorf, W.J., and J.T. Leffingwell. 1982. Regu-
lating OP pesticide residues for farmworker protection. Residue
Reviews 82:125-201.
(12) Task Group on Occupational Exposure to Pesticides,
Federal Working Group on Pest Management. 1974. Occupational
Exposure to Pesticides. U.S. Environmental Protection Agency,
Washington, D.C. 20460.
(13) U. S. Department of Health, Education, and Welfare.
1975. Protection of Human Subjects. Code of Federal Regulations;
Title 45, Part 46.
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SUBDIVISION K — EXPOSURE: REENTRY PROTECTION
Series 130: GENERAL PROVISIONS
§ 130-1 Basic guidance.
(a) Purpose and scope. (1) This subdivision describes the
requirements of 40 CFR § 158.140 for registration support data which
the Agency will evaluate in order to determine what label restrictions,
if any, are needed to protect people who enter a site which has been
treated with a pesticide. Human protection through minimization of
human exposure to pesticide residues is the purpose of 40 CFR § 158.140
and this subdivision. The Agency requirements for data required by
40 CFR § 158.140 will be based upon:
(i) Determination of the time necessary for pesticide residues
at the treated site to decline to an allowable reentry level (a
level which will not be hazardous to humans);
(iij Placement of a reentry interval (interval during which
no entry to the treated site should routinely be permitted) on a
pesticide label; and/or
(iii) Judgment as to the utility, availability, and likelihood
of use of personal protective equipment to be used by people entering
a treated site.
(2) The reentry level is a level of pesticide residues in the
environment which will not cause unreasonable adverse health effects
in people entering a treated site without use of personal protective
equipment. The reentry interval is the time it takes for the pesti-
cide residues to dissipate to the reentry level. Use of personal
protective equipment and other measures will be required, when it
is necessary for people to enter a site before the pesticide resi-
dues have dissipated to the reentry level.
(3) Data necessary to determine reentry levels and reentry
intervals include:
(i) Data on toxicity of the pesticide;
(ii) Data on expected human exposure to the pesticide residues
from typical human activities that would take place at a site that
has been treated with a pesticide; and
(iii) :Data on the nature and amount of pesticide residues
remaining at the treated site (on foliage, soil, or other .surfaces
and in the air).
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(b) Use of reentry interval. The applicant should submit a
label for the prospective product which will include a proposed re-
entry interval. This proposed interval is to be supported by data
required by 40 CFR § 158.140 and described in § 130-3 of this sub-
division. The Agency will review the data and accept or reject the
proposed interval.
(c) Application status and compliance. The requirements of
40 CFR § 158.140 apply to products already registered, as well as
those being proposed for registration. The Agency will notify
registrants of products already registered, either (occasionally)
through the data call-in program or (routinely) upon development
of a registration standard, as to when they must satisfy the data
requirements of this subdivision. Refer to 40 CFR 158 for details
on application status in relation to submittal times.
(d) Formulators* exemption. As provided by 40 CFR § 158.50,
an applicant for registration of an end-use product who purchases
and legally uses a registered product to formulate the end-use
product is not usually required to submit or cite data discussed in
this subdivision. Such a purchased product must be registered and
labeled for manufacturing use or for the same use as the end-use
product being formulated by the applicant. This is consistent with
the Congressional intent as set forth in sec. 3(c)(2)(D) of FIFRA,
which provides that:
"No applicant for registration of a pesticide who proposes
to purchase a registered pesticide from another producer in
order to formulate such purchase pesticide into an end-use
product shall be required to—
(i) submit or cite data pertaining to the safety of
such purchased product; or
(ii) offer to pay reasonable compensation otherwise
required by [§ 3(c)(l)(D) of FIFRA] for the use of any such
data."
Since studies required by 40 CFR § 158.140 and discussed in this
guidelines subdivision would ordinarily be conducted by the basic
manufacturer, pesticide formulators would not often be expected to
conduct such tests themselves to develop data to support their
individual products. They may do so if they wish, but they may
merely rely on data developed by the manufacturing use producer.
(e) "When required" and "test substance" requirements. The
registration applicant should be careful to distinguish between the
"when required" and the "test substance" paragraph requirements of
each section of this subdivision:
(1) The "when required" paragraphs pertain to the circum-
stances under which data are required by 40 CFR § 158.140 and
specify-, the categories of products for which data must be generated
to support registration applications. The test data are ordinarily
required to support the registration of each end-use product with
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the prescribed use type and each manufacturing-use product used to
make such an end-use product.
The "test substance" paragraphs refer to kinds of testing
required, ;''to produce acceptable data and state the kind of pesticide
mate'riaf that must be used in each test. The test substance for
studies described in this subdivision must be a typical end-use
product, as required by 40 CFR § 158.140.
(f) General references. Information concerning the history
of the reentry problem, the present state of the art, recent exper-
imental activity, and suggested approaches to reentry assessment
can be found in the following references:
(1) Task Group on Occupational Exposure to Pesticides, Federal
Working Group on Pest Management. 1974. Occupational Exposure to
Pesticides. U.S. Environmental Protection Agency, Washington, D.C.
20460. [This review contains a history and discussion of the
problem of f ieldworker poisonings with organophosphorus pesticide
residues on crops up to 1974.]
(2) Gunther, F.A. , Y. Iwata, G.E. Carman, and C.A. Smith.
1977. The citrus reentry problem: research on its causes and effects,
and approaches to its minimization. Residue Reviews 67:1-139.
[This review is recommended as a starting point for information on
the reentry problem and for references to research on the subject
up to 1977. The literature review is exhaustive and the index is
useful.]
(3) Gunther, F.A. , and J.D. Gunther (eds.). 1980. Minimizing
occupational exposure to pesticides. Residue Reviews, Volume 75.
[This entire volume constitutes the proceedings of a conference on
reentry and contains a number of papers on various topics underlying,
the prevention of field worker poisonings.]
(4) Popendorf, W.J., and J.T. Lef f ingwell . 1982. Regulating
OP pesticide residues for farm worker protection. Residue Reviews
82:125-201. [This paper contains a review of the literature as
support for the authors' suggested model for the calculation of
reentry intervals.]
§ 130-2 Definitions.
(a) Terms used in this subdivision have the meanings set
forth at 40 CFR § 162.3 and at 40 CFR 158.
(b) In addition, for the purposes of this subdivision:
(1) The term "airborne residue" means residue of a pesticide,
including vapors, aerosols, and airborne particulates, that remains
suspended in the air after pesticide application or is caused to
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become suspended in the air at a treated site during a normal human
activity.
,-.-.. (2) The term "allowable exposure level" or "AEL" means the
^maximum amount of combined dermal and inhalation exposure which is
:>qsnsidered not to cause unreasonable adverse effects to people
: entering a previously treated site. An AEL will generally be based
on animal toxicity studies and adjusted by means of an appropriate
safety factor.
(3) The term "dermal exposure" means the process by which
pesticide residues are deposited on the skin of people entering a
previously-treated site. The term also refers to a measure of the
amount of residue deposited by such exposure. It is synonymous
with the external dermal exposure, and it is not necessarily
equivalent to the amount of residue which would be absorbed into
the body through the skin.
(4) The term "direct exposure method" means a procedure for
measuring the quantity of pesticide residue transferred to a person's
skin or respiratory tract. This method would involve, but not be
limited to, measuring residues on dermal patches or respirator
filters. This method excludes indirect exposure methods, such as
quantification of pesticide residues in blood, urine, or tissues,
and excludes measurement of physiological changes, such as changes
of blood enzyme activities.
(5) The term "dislodgeable residue" means that portion of
pesticide residue on a surface that can be dislodged from that
surface by human activities involving contact with the surface.
The term also includes residue that can be dislodged by dissolving
in moisture (dew, rain, perspiration) and which then can contaminate
skin, respiratory tissues, hair, clothing, etc., of people entering
the treated site. The surfaces involved include, but are not '
limited to, foliage, agricultural produce, and soils.
(6) The term "dissipation curve" means a plot of the logarithm
of pesticide residue level against time of sampling, or the
mathematical representation of such a plot.
(7) The term "early reentry" means the entry of people into a
site previously treated with a pesticide prior to expiration of any
established, pertinent reentry interval.
(8) The term "inhalation exposure" means the process by which
pesticide residues are inhaled by a person in a treated site. The
term also refers to the quantity of residue sorbed by respiratory
tissues by such a process. This term is synonymous with pulmonary
or respiratory exposure, and is not necessarily equivalent to the
amount of residue which would be absorbed into the body through the
pulmonary system.
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(9) The term "personal protective equipment" means special
clothing, hats, shoes, gloves, respirators, or other devices attach-
ed to or covering people and intended to reduce human exposure to
pesticide residues. This term refers to items that normally would
not be used in the absence of pesticide hazards and that would
provide greater protection to people than normal attire.
(10) The term "proposed reentry interval" means a reentry
interval proposed by an applicant as adequate for human protection.
(11) The term "reentry" means the entry of one or more people
into a site subsequent to pesticide application.
(12) The term "reentry interval" means the length of time
that must elapse after pesticide application before people who are
not using personal protective equipment may enter the treated site
without risk of any unreasonable adverse effects due to exposure to
pesticide residues. This term is synonymous with "reentry time"
[cf. 40 CFR § 170.2(a)].
(13) The term "reentry level" means the maximum level of pesti-
cide residues at a treated site that is not likely to pose unreason-
able adverse affects on people entering the site without personal
protective equipment.
(14) The terms "residue(s), pesticide residue(s), and residue(s)
of a pesticide" mean active ingredient(s), toxic impurities of the
pesticide, and toxic alteration products of the active ingredient
that remain at the site of application or that remain on items that
are subsequently removed from the site.
(15) The term "site" means a specific agricultural area such
as a field, grove, vineyard, or orchard.
(16) The terms "surrogate", "surrogate of a pesticide", or
"pesticide surrogate" means a chemical compound or a mixture of
compounds other than the pesticide being investigated which could
be used to quantify human exposure. The surrogate could be an
active ingredient of a pesticide previously registered for that
use. See § 133-2 for further information.
(17) The term "task" means a human work activity performed
according to current commonly-recognized practice or any other .
human activity that could cause exposure to pesticide residues at .
the site.
(18) The term "typical end-use product" means a pesticide
product that is representative of a major formulation category
(e.g., emulsifiable concentrate, granular product, wettable powder)
and contains the active ingredient of the registration applicant's
product.
(19) The term "use type" means a grouping of crops or plants
with similar potential for exposure during reentry activities.~.
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§ 130-3 Requirement for reentry interval and supporting data.
(a) When required. A reentry interval and the supporting
data discussed in this subdivision are required by 40 CFR § 158.140
to support the registration of each end-use product that meets one
or more of the toxicity criteria specified in paragraph (1) below,
and that has a use type that could be included in the use classifi-
cations specified in paragraph (2) below.
(1) Toxicity criteria. If the pesticide toxicity data meet
one or more of the following criteria based on toxicity studies
required under 40 CFR § 158.135, then a reentry interval and support-
ing data are required:
(i) If the 11)50 of the technical grade of any active ingredient
in the end-use product is less than 200 mg/kg (body weight) as
determined by acute dermal toxicity testing (§ 81-2); or
(ii) If the LCso of the technical grade of any active ingre-
dient in the end-use product is less than 200 mg/m^ (for a one-hour
exposure) as determined by acute inhalation toxicity testing
(§ 81-3); or
(iii) If the LEkjQ of the technical grade of any active ingre-
dient in the end-use product is less than 50 mg/kg (body weight)
as determined by acute oral toxicity testing (§ 81-1); or
(iv) If neurotoxic, teratogenic, or oncogenic effects, as
evidenced by studies conducted in accordance with §§ 81-7, 82-5,
83-2, or 83-3, or other adverse effects as evidenced by subchronic,
chronic, and reproduction studies conducted in accordance with
§§ 82-1, -2, -3, -4, 83-1, and -4, would be expected from entry
of persons into treated sites, taking into account the pattern and
frequency of pesticide use and the results of a risk analysis based
on margins of safety or derived from mathematical models according
to § 131-3; or
(v) If the Agency receives other scientifically validated
toxicological or epidemiological evidence that a pesticide or
residue of a pesticide could cause adverse effects to persons
entering treated sites. In this situation, reentry intervals and
supporting data may be required on a case-by-case basis.
(2) Use types. The following pesticide use types are subject
to the requirement for submittal of proposed reentry intervals and
the corresponding data;
(i) Applications to growing crops, such as typical applica-
tions of insecticides, fungicides, and herbicides made to or around
all horticultural and agronomic crops that are field- or orchard-
grown;
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(ii) Uses of pesticides to all outdoor tree nursery and
forestry operations;
(iii) Applications to turf crops and commercial applications
to turf; and
(iv) Applications to parks and arboretums.
(b) Waivers. (1) General waiver. An applicant for regis-
tration may request a waiver from the requirement to submit some
or all of the data required by 40 CFR § 158.140 and described in
this subdivision provided that he submits written evidence that
such data are inapplicable to the specific pesticide or product.
(2) Waiver for no substantial exposure. The applicant may
provide a description of sites and human reentry activities (See
§ 133-1) revealing that no substantial human exposure to pesticide
residues can be reasonably foreseen. If the applicant also requests
a waiver from the requirement to provide a reentry interval on a
particular product label, the Agency will review the request and
the descriptions submitted. If the Agency agrees with the submitted
rationale, it will grant a waiver.
(3) Waiver for other specific reasons. The applicant may
request a waiver from submittal of certain data required by 40 CFR
§ 158.140 and discussed in this subdivision, if he submits evidence
that specific properties or characteristics of his pesticide or
product preclude the requirement for such data. Such properties or
characteristics could include, but are not limited to, the composi-
tion, degradation rate, toxicity, and such other chemical and phys-
ical properties of a specific pesticide or product that are funda-
mentally different from the factors considered by .the Agency in the
establishment of the data requirements of 40 CFR § 158.140.
(c) Exposure only to airborne residues covered by other
regulations. In the case of reentry to a site which is expected to
involve only exposures to airborne residues which are covered by
the Permissible Exposure Limits developed by the Occupational Safety
and Health Administration (29 CFR § 1910.1000) or the Threshold
Limit Values (TLV) developed by the American Conference of Govern-
mental Industrial Hygienists (ACGIH), those limits may serve as
reentry levels for airborne residues and can be used by a registrant
for determination of a proposed reentry interval.
§ 130-4 General reporting requirements.
(a) General. Each test report submitted to meet the require-
ments of 40 CFR § 158.140 should include the following information
specified in paragraphs (b), (c), and (d) of this section, unless
a specific section elsewhere in this subdivision indicates otherwise.
The registration applicant should remember that standardization of
data reporting and submission of a complete report will expedite
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the review process. Multipurpose data should be referenced to
specific pages in other volumes or be duplicated and submitted in
each appropriate volume.
(b) Test report. The test report should include all informa-
tion necessary to provide a complete and accurate description of
test procedures, materials, results, and analysis of the data, a
statement of conclusions drawn from the analyses, and a tabular
sunmary and abstract of results. Units of measurement should be in
the metric system, but the English system may, in addition, be
used. The two systems should not be mixed (e.g., g/ft^). The
statement of test method(s) used should include a full description
of the experimental design, the site(s) or location(s), duration,
and actual dates of the study.
(c) Deviation. The report should indicate all ways in which
the test procedure failed to meet applicable standards for acceptable
testing contained in this subdivision, and should state the reasons
for such deviations.
(d) Test substance. (1) The test substance should be
identified, including chemical name, molecular structure, and a
quantitative and qualitative determination of its chemical composi-
tion (including names and quantities of known contaminants and
impurities, so far as technically feasible). The determinations
should also include quantities of unknown materials, if any, so
that 100 percent of the sample tested is accounted for. This
information would ordinarily be developed to meet the requirements
of 40 CFR § 158.120 discussed in Subdivision D.
(2) Manufacturer and lot and sample numbers of the test
substance should be reported.
§ 130-5 Coordination with other requirements in 40 CFR Part J58.
The applicant should determine whether studies conducted to
meet the requirements of 40 CFR § 158.140 can be coordinated with
studies required by other sections of 40 CFR Part 158, such as
§ 158.160 discussed in Subdivision G (Product Performance); § 158.150
discussed in Subdivision J (Hazard Evaluation: Nontarget target
Plants); § 158.130 discussed in Subdivision N (Chemistry Require-
ments: Environmental Fate), and § 158.125 discussed in Subdivision
0 (Chemistry Requirements: Residue Chemistry). The studies should
be coordinated with the data gathered to meet the requirements of
40 CFR § 158.135 discussed in Subdivision F (Hazard Evaluation:
Humans and Domestic Animals) and with information from Subdivision
I (Experimental Use Permits). The applicant should also be cogni-
zant of the labeling implications of this subdivision in relation
to Subdivision H (Label .Development). In addition, some of the
studies might be usefully coordinated with those required for .
supporting a tolerance or temporary tolerance petition under the
Federal Food, Drug and Cosmetic Act.
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Series 131: TOXICITY DATA
§ 131-1 Data required.
The toxicological data sutmitted by registration applicants to
evaluate the toxicity of a pesticide to humans and domestic animals
as required by 40 CFR §158.135 should be used to determine an allow-
able exposure level (AEL) for use in proposing reentry intervals.
Those data are described in the following sections of Subdivision F.
Acute oral toxicity § 81-1
Acute dermal toxicity § 81-2
Acute inhalation toxicity § 81-3
Primary eye irritation § 81-4
Primary dermal irritation § 81-5
Dermal sensitization § 81-6
Acute delayed neurotoxicity § 81-7
Subchronic oral toxicity § 82-1
Subchronic dermal toxicity § 82-2,-3
Subchronic inhalation toxicity § 82-4
Subchronic neurotoxicity § 82-5
Chronic toxicity § 83-1
Oncogenicity § 83-2
Teratogenicity § 83-3
Repro. and fertility effects § 83-4
Combined chronic tox./oncogen. § 83-5
Mutagenicity § 84-2
§ 131-2 Exposure conversions and penetration assumptions.
(a) General procedure. (1) The allowable exposure level
(AEL) should be determined by the applicant fron either:
(i) Animal dermal and/or inhalation toxicity data from acute
and subchronic studies conducted to meet the requirements of 40 CFR
§ 158.135, as described in subdivision F (§§ 81-2, -3, §§ 82-2,
-3, and -4); or
(ii) The no observed effect levels (NOELs) fron subchronic
dermal and/or subchronic inhalation studies.
(2) The toxicity data used for this determination should be
that which gives the lowest AEL.
(b) Use of data from other studies. When NOELs from studies
such as subchronic neurotoxicity, teratogenicity, and reproduction
are lower than NOELs from subchronic dermal and/or inhalation
studies, the data from the studies yielding the lower NOELs should
be used to determine the AEL.
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(c) Conversion of toxicity data frcm oral routes to dermal
routes. The following considerations may be helpful if it is neces-
sary to convert toxicity data obtained from animals dosed by oral
route to approximate absorbed dermal dose.
(1) Comparison of acute oral LDso ar*d acute dermal LDsg (see
§§ 81-1 and -2);
(2) Physical state of the pesticide when exposure is expected
(e.g., liquid, dust, granular, or encapsulated residues); and
(3) Actual dermal absorption data from experimental animal
studies with the same or analogous chemicals [see also paragraph
(d)(l) of this section].
(d) Absorption. For estimating penetration of pesticides
through skin, the applicant may either assume 100 percent absorption
or submit data including, but not limited to, that described in
paragraph (c) above, to indicate that absorption is less than 100
percent. For penetration of pesticides through lung surfaces, the
Agency will assume 100 percent penetration unless adequate data are
submitted by the applicant to indicate otherwise.
§ 131-3 Determining allowable exposure level.
(a) When required. An allowable exposure level (AEL) for
each active ingredient in an end-use product is required to support
the registration of each end-use product for which a reentry inter-
val is required by 40 CFR § 158.140 and discussed in § 130-3 of this
subdivision.
(b) Determining the AEL. The procedure used to determine an
AEL will depend on the kinds of toxic effects produced by the active
ingredient and on the extent of absorption. If the active ingredi-
ent does not produce oncogenic effects, the AEL should be determined
using the guidance and considerations in paragraph (b)(2) of this
section. The applicant may determine an AEL using other means and
submit supporting data for the approach.
(1) Non-oncogenic substances. The no observed effect levels
(NOELs) discussed in § 131-(2) should be divided by an appropriate
safety factor to determine the AEL. This safety factor should
reflect the degree or amount of uncertainty to be considered when
experimental data in animals are extrapolated to effects on man.
Safety factors may vary from 10 to 2000 and should reflect the
nature of the toxicity (severity and reversibility), the length of
the exposure, and the comparability (if known) between the animal
and humans for pesticide absorption, distribution, excretion, and
metabolic transformations. The NOELs frcm subchronic dermal or
subchronic inhalation studies should generally be used to determine
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the allowable levels of human exposure. However, when a NOEL from
studies such as subchronic neurotoxicity, teratology, and reproduc-
tion are lower, the NOEL derived from these studies should be
used. If the animal studies are those which do not yield a NOEL,
then appropriate levels of risk should be used to determine an
allowable exposure level.
(2) Oncogenic substances. The AEL for oncogenic substances
should be based on a risk assessment using appropriate mathematical
models applied to data derived from life-time animal studies. The
applicant may determine an AEL using other means but should submit
data to support the approach. The Agency can provide instructions
for risk assessment and for calculation of the AEL.
(c) Reporting of AEL. (1) If the end-use product contains
more than one active ingredient, the lowest AEL should be reported.
(2) The AEL should be expressed in terms of daily dermal dose
(such as mg/kg/day) or, in the case of airborne residues, in terms
of airborne concentrations (such as mg/rn^).
(3) The report on the calculation of the AEL should indicate
the data used, any safety factor used, the mathematical model (if
any), and the reasons for selecting each.
Series 132: RESIDUE DISSIPATION DATA
§ 132-1 Requirements for residue dissipation data.
'<
(a) When.required. When a reentry interval is required under
40 CFR § 158.140 [see § 130-3(a)], that part also requires residue
dissipation studies as described in § 132-2 for residues of the
applicant's pesticide to support the proposed reentry interval.
(b) Selection of study. The type of residue dissipation study
(or studies) that will be required will be based on the use type:
(1) Products intended for foliar application to agricultural
crops should be supported by data from a study of the dissipation of
foliar dislodgeable residues with respect to time;
(2) When a task will cause substantial human contact with
soil, a study of dissipation of residues from soil surfaces with
respect to time is needed.
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§ 132-2 Dissipation of dislodgeable residues.
(a) Purpose. Requirements of 40 CFR § 158.140 and described
in this section are confined to the measurements of pesticide resi-
dues which are deposited on and remain on surfaces after pesticide
application. These surfaces are limited to those that can be
touched or disturbed by people, and from which residues can be
dislodged during the performance of various tasks and subsequently
deposited on human skin and clothing or inhaled.
(b) When required. Data on residue dissipation are required
for each manufacturing-use product whose use is likely to cause
dislodgeable residues on surfaces and for which a reentry interval
is required under 40 CFR § 158.140 [See § 130-3 of this subdivision],
(c) Test standards. (1) Test substance. A typical end-use
product should be used for this study.
(2) Sites for conduct of tests. Since climate strongly influ-
ences the dissipation of pesticide residues, the applicant should
perform dissipation study at a site representative of the climatic
conditions expected in the intended use areas. The Agency will -
provide guidance on the choice of site upon request.
(3) Substitutions for sites. In certain cases, data from one
site (when available) may be substituted for data from another site
when surface characteristics are generally similar or nearly iden-
tical (e.g., orange and grapefruit orchard applications). For those
cases, available residue data should demonstrate that dissipation
rates at the two sites do not differ significantly for similar use
patterns.
i . . . 'j -
(4) Method of application. The test substance should be
applied by application methods recommended for the end-use product.
Application of the test substance to the site, area, or objects
should be at the least dilution and highest rate permitted for that
end-use product.
(5) Timing of application. The test substance should be
applied at the time of year or season that would normally be
reconnended to achieve satisfactory pest control by the product.
(6) Meteorological conditions. Daily meteorological condi-
tions at or near the site of application should be recorded as part
of the data in this study. Such data would include, as appropriate,
temperature, wind speed, daily rainfall, humidity, and similar
information.
(7) Standards for sample collection, (i) Duplicate samples.
Duplicate foliar samples should be collected periodically for the
development of dissipation curves. The first samples should be
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taken as soon as the spray has dried or the dust has settled. The
intervals at the start of sampling should be relatively short and
may increase with time. For example, samples taken as soon as the
spray has dried or the dust has settled, and at 1, 2, 5, 7, 14, 21,
28, and 35 days after pesticide application would probably be
appropriate for some pesticides. Comparable control or baseline
samples should be collected immediately before the pesticide applica-
tion. If analyses of samples reveal dislodgeable residues above
the reentry level, sampling and analyses should continue until a
level at or below the reentry level is reached.
(ii) Additional standards for soil samples. (A) Whenever the
applied pesticide deposits on, is incorporated into, or diffuses
into soil at the site of application and whenever tasks at the
treated site will involve exposure of workers to large amounts of
soil, duplicate soil samples for pesticide residue analysis should
be collected from the soil surface or from not more than the upper
one centimeter of soil in the test plot.
(B) The fine material should be isolated from the soil samples
without grinding to give all of the material having particle sizes
of 147 microns or less without particles larger than 147 microns.
The fine material will be extracted for residue analysis.
(iii) Sample storage. Samples and sample extracts may be
stored for later analysis only if fortified controls are included
to permit evaluation of possible residue deterioration during
storage. Such samples should be stored under conditions which will
minimize deterioration.
(8) Procedures for chemical extraction and analysis. The
dislodgeable pesticide residues should be extracted from the foliar
material and soil, isolated from interfering materials by suitable
cleanup procedures, and quantified.
(d) Reporting of test results. In addition to meeting the
general reporting requirements of 40 CFR § 158.140 [See § 130-4],
the test report should also meet the following requirements:
(1) For surface residues such as foliar residues, the analyt-
ical results should be expressed in terms of milligrams or micrograms
of residues per square centimeter of surface (e.g., leaf surface).
It will be necessary to estimate the surface area of extracted
leaves that are too small for a standard leaf punch to be used.
(2) For residues on media such as soil, the analytical results
should be expressed in terms of micrograms per gram of fine material.
The fine material should be reported in milligrams or micrograms per
square centimeter of surface of the soil area from which the sample
was obtained.
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(e) Evaluation and use of data. Data obtained from this
study are for the development of dissipation curves which can be
used in the calculation of reentry intervals according to the
approaches described in section series 134 of this subdivision.
(f) References. (1) Experimental procedures for determina-
tion of dislodgeable foliar residues are given in the following
publications:
(i) Gunther, F.A., W.E. Westlake, J.H. Barkley, W. Winterlin,
and L. Langbehn. 1973. Establishing dislodgeable pesticide resi-
dues on leaf surfaces. Bull. Environ. Contain. Toxicol. 9:243-249.
[Also included in this reference are discussions of sampling proce-
dures and a description of leaf punches used in sample collection.]
(ii) Iwata, Y., J.B. Knaak, R.C. Spear, and R.J. Foster.
1977. Worker reentry into pesticide treated crops. I. Procedure
for the determination of dislodgeable residues on foliage. Bull.
Environ. Contain. Toxicol. 18:649-655. [This is a recent modifi-
cation of the above procedure for quantification of dislodgeable
residues and increases the applicability of the method. Although
additional research may uncover other methods more predictive of
the respiratory and dermal dose variable, at present these tech-
niques are the most suitable for foliar residues.]
(2) Experimental procedures for the determination of pesti-
cide residues on fine soil particles can be found in the following
publications:
(i) Spencer, W.F., Y. Iwata, W.W. Kilgore, and J.B. Knaak.
1977. Worker reentry into pesticide treated crops. II. Procedures
for the determination of pesticide residues on the soil surface.
Bull. Environ. Contain. Toxicol. 18:656-662. [This paper contains a
procedure for sampling of fine, dry particulate matter from the
soil surface and a procedure for extraction of pesticide residues
from soil.]
(ii) Berck, B., Y. Iwata, and F.A. Gunther. 1981. Worker
environment research: Rapid field method for estimation of organo-
phosphorus insecticide residues on citrus foliage and in grove soil.
J. Agric. Food Chem. 29:209-216. [The procedure for sampling fine
surface soil material in this paper may be appropriate for damp
soils as well as wet soils.]
(iii) Smith, C.A., and F.A. Gunther. 1978. Rapid estimation
of organophosphorus pesticide residues in citrus grove soil. Bull.
Environ. Contain. Toxicol. 19:571-577. [This paper reports proced-
ures for analysis in the field of pesticide residues sorbed to
surface soil.]
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Series 133: MEASUREMENT OF HUMAN EXPOSURE
§ 133-1 Descriptions of human activity.
(a) Purpose. The purpose of this section is.to delineate the
requirements for developing and submitting descriptions of human
activities likely to occur at a site that has been treated with a
specific pesticide.
(b) When required. The registration of a manufacturing-use
product should be supported by a brief description of each of the
human activities associated with each of the general use patterns
for which a reentry interval is required by 40 CFR § 158.140 [See
§ 130-3]..
(c) Description of activities. Each brief description pre-
pared in accordance with the requirement of paragraph (b) of this
section should include, but not necessarily be limited to:
(1) Nature of human activity (e.g.", harvesting, thinning,
scouting, etc.);
(2) Principal source(s) of exposure (e.g., foliage, soil,
air, etc.);
(3) Usual environmental conditions for activity (e.g., hot,
humid, cool, dry, wet, etc.);
(4)'.Level of physical exertion (e.g., mild, moderate, heavy);
and -;!
(5f Expected frequency and duration of activity (e.g., number
of times per day or per week, number of hours per day, etc.).
(d) Designation of maximum exposure activity. In connection
with the submittal of descriptions of human activities discussed in
paragraph (b) of this section, the applicant should state which
activity is the most likely to result in maximum human exposure to
pesticide residues for each site. In some pesticide use situations,
the most significant human exposure to pesticide residues occurs
when harvested commodities are transferred from the application .
site and handled (e.g., sorting of fruits or vegetables). The
applicant should include a brief rationale supporting his selection.
The activity selected will represent the maximum expected exposure
activity for that specific use, and may be employed as the exposure
standard for future calculations under § 134-2 of this subdivision,
if that section is used for calculating a reentry interval.
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§ 133-2 Requirements for exposure data.
(a) Purpose and scope. (1) The purpose of this section is
to delineate the requirements for developing and submitting data.-
relating to human exposure for purposes of supporting reentry
intervals proposed according to § 134-2. The registration appli-
cant should understand that useful exposure studies using surrogate
chemicals — often other pesticides — may already exist and may be
cited to meet the requirements of 40 CFR § 158.140 discussed in
this section; actual conduct of the study may be unnecessary if
these data are cited. Therefore, the applicant should consult with
the Agency before undertaking such studies. The submission and use
of extant human exposure data on a surrogate pesticide is encouraged
by the Agency and is acceptable if the registrant submits descrip-
tions demonstrating that the sites and human activities for which
the surrogate exposure data were obtained produce exposure which is
greater than or substantially similar to those for which the reentry
interval is being proposed.
(2) A registration applicant should not undertake or authorize
development of information to meet.the requirements of this section
in such a manner as to pose a hazard to people assigned to perform
activities in the study. The Guidelines for Protection of Human
Subjects [45 CFR 46] promulgated by the U. S. Department of Health,
Education, and Welfare contains information that should be consider-
ed for design of such studies. Before conducting any such studies,
registration applicants should submit study protocols for approval
by the appropriate institutional review board or public health
department in states where the studies are to be performed.
(3) Any studies or monitoring conducted pursuant to this
"section must not violate FIFRA sec. 12(a)(2)(P) which provides that
/"....it shall be unlawful for any person in any State to use any
pesticide in tests on human beings unless such human beings (i)
are fully informed of the nature and purpose of the test , and
(ii) freely volunteer to participate in the test."
(b) When required. Data relating to human exposure are also
required by 40 CFR § 158.140 when reentry intervals are required by
§ 158.140 as discussed in § 130-3 and when the applicant elects to
propose reentry intervals using the method in § 134-2.
(c) General test standards. (1) The applicant should obtain
data from one or more studies regarding the quantity of pesticide
residues that would be expected:
(i) To be deposited on the skin and clothing of a person
undertaking the maximum exposure activity upon reentry.
(ii) To be inhaled by a person undertaking the maximum exposure
activity upon reentry.
(iii) To result in a dose to a person by any combined route of
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intake that would be appropriate for the maximum exposure activity
upon reentry.
(2) Different sites may result in very similar exposures to
people engaged in the same general tasks (e.g., lettuce and cabbage
harvesting). If data on other pesticides indicate that this is the
case, data for one site may be used to estimate exposure at another
site. A detailed explanation of any extrapolation processes used,
such as from published studies to the study undertaken or from
studies on exposure in one crop to their use on another crop, should
be reported.
(d) Reporting requirements. The applicant should submit a
complete description of the results of the exposure study, includ-
ing all supporting data, extrapolations, estimates, and other
relevant information. Such a description should include, but not
be limited to:
(1) A complete description of the selected task (or tasks)
used in the exposure study (See § 133-1).
(2) A complete description of the end-use product used for
the study.
(3) A complete description of the statistical approaches and
treatment of data for the study.
§ 133-3 Measurement of dermal exposure.
(a) Purpose. Use of data on dermal exposure to the pesti-
cide or a surrogate by means of a direct exposure method is required
by 40 CFR § 158.140 so that the amount of dermal exposure during the
performance of an activity at a site can be estimated. The data
will then be used for the calculation of reentry levels and the
establishment of reentry intervals as described in section series
134.
(b) When required. (1) Use of data on the estimated dermal
exposure of humans are required by 40 CFR § 158.140 to support the
registration of an end-use product if:
(i) A reentry interval is required as discussed in § 130-3 of
this subdivision; and
(ii) The reentry interval is determined by the method described
in § 134-2.
(2) If the reentry interval for a use pattern is determined
by the non-detectable residue method described in § 134-1, then
the data requirements of this section do not apply.
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(c) Combined studies. (1) Direct measurement of dermal expo-
sure to a pesticide should be combined with measurement of inhala-
tion exposure as described in § 133-4 when both types of data are
required. The applicant should be certain that the standards for
both types of studies are met.
(2) Measurement of dermal exposure to a pesticide during re-
entry into leafy crops should be combined with measurement of dis-
lodgeable foliar residues. If significant exposure from soil-borne
residues is expected, these measurements should be combined with
quantification of soil residues. The measurement of dermal exposure
may be combined with studies discussed in other sections of this
subdivision and in other subdivisions of these guidelines, such as
Subdivision G (Product Performance), Subdivision J (Hazard Evalua-
tion: Nontarget Plants), Subdivision N (Chemistry Requirements:
Environmental Fate), and Subdivision 0 (Chemistry Requirements:
Residue Chemistry), and coordinated with Subdivision I (Experimental
Use Permits).
(d) Test standards. In addition to meeting the general
standards set forth in § 133-2(c), a direct dermal exposure study
should also meet the following standards:
(1) Study substance. A typical end-use product should be
used in these studies to support registration of the pesticide.
(2) Conduct of studies, (i) Attachment of exposure pads.
Dermal exposure should be assessed by use of multilayered gauze pads.
Pads should be attached to the subjects as specified in Table 1.
Each pad should be numbered so that resulting data can be related
to the subject and the location of the pad on the subject.
(ii) Assessment of hand exposure. Light cotton gloves should
be used to trap residues of the pesticide or surrogate in order to
develop data for assessing dermal exposure of human hands.
(iii) Handling of samples. Special care should be taken to
protect the samples in the field. Glove and pad samples should be
transported to the laboratory in sealed containers. The containers
should be chilled or frozen to minimize residue losses in transit
and storage.
(iv) Typical activities. All activities contributing to the
exposure being studied should be carried out in a manner consistent
with current agricultural practice.
(v) Pesticide application. (A) Application rates. Applica-
tions should be made at the maximum rate proposed for the end-use
product, application method, and application situation being studied.
(B) Application method. Exposures should be determined after
pesticide application by the method that experience has shown to
cause the maximum residue levels.
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(vi) Duration of exposure. The exposure period should be long
enough for measurable residues to be collected if exposure is occur-
ring, but short enough to avoid excessive losses, it is impossible
to specify an exact duration of exposure that will give satisfactory
results for a given activity, and-this factor is left to the judg-
ment of the investigator.
(vii) Number of replicates. The'applicant should collect dermal
exposure replicates sufficient for statistical validation of the
exposure. It is suggested that ten workers be monitored in a test for
dermal exposure. When small test plot size makes this impossible,
the number of replicates could be increased by monitoring exposure
for shorter periods.
(3) Residue extraction. The pesticide residues should be ex-
tracted from the pads and gloves, and the extracted residues should
be separated from interfering substances (e.g. by liquid chromato-
graphy) before being quantified. A study should be conducted or
cited that measures the efficiency of the method chosen to extract
residues from exposure pads and gloves.
(4) Residue analysis. The residues should be quantified by
a procedure capable of quantitative detection of residues on
exposure pads or gloves at levels of 0.2 ug/cm2 or less. A study
should be conducted or cited demonstrating that the analytical
procedure chosen is capable of detection at that level.
(5) Stability of compounds, (i) Stability of compounds on
stored pads and gloves. If exposed pads or gloves are to be stored
for longer than 24 hours, a study of the stability of the residue
stored on moist exposure pads and on moist gloves should be conducted
under the conditions to be used for storing the field samples. The
storage times should be chosen so that the longest corresponds to
the longest projected storage period for field samples and so that
a decay curve can be constructed to allow extrapolation of residue
levels found in field samples back to the time of collection. The
pads and their protective containers should be extracted and analyz-
ed by the methods to be employed in the field studies. Storage of
field samples should not exceed periods that would result in loss
of 50 percent or more of the original residue.
(ii) Stability of extracts. If extracts from pads or gloves
are to be stored for longer than 24 hours before analysis, a study
of stability should be conducted or cited for the solvent used. The
storage times should be chosen so that the longest corresponds to the
longest projected storage period for extracts from field samples and
so that a decay curve can be constructed to allow extrapolation of
residue levels found in stored extracts back to the time of extrac-
tion. Storage of extracts from field samples should not exceed
periods that would result in loss of 50 percent or more of the
residue originally extracted.
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(e) Reporting of study results. -(1) General site data. The
following data should be reported for each treated site where expo-
sure data are collected: -
(i) Chemical name of pesticide or surrogate;
(ii) Type of formulation;
(iii) Method of application;
(iv) Application rate;
(v) Residue levels on pertinent surfaces as listed in
§ 132-1;
(vi) Dimensions of the treated site;
(vii) Environmental conditions during the exposure test;
(viii) Crop (if involved); and
(ix) Activity of study subjects at the site during the
exposure.
(2) Data for individual subjects. Each study subject should be
identified by name or number. A set of field data should be compiled
for each subject in the study. These data sets should be indexed so
that each subject and the intensity of that subject's activity can
be related to the exposure levels found. The following data should
be reported for each subject:
(i) Subject identification;
(ii) Some measure of intensity or productivity of the
subject's activity during exposure (e.g., pounds of fruit picked/
hour);
(iii) Pad number and pad location; and
(iv) Levels of toxic pesticide residues on each pad in
ug/cm2/nr.
(3) Analysis. Laboratory operations should be recorded on a
sample history sheet which should include the sample number and
dates of collection, extraction, and analysis for each sample.
Paired pads may be combined for extraction and residue analysis.
(4) Calculations. For the calculation of dermal exposures of
body areas expected to be exposed during reentry activities, the
human body surface areas listed in Table 2 can be used as a guide.
The dermal exposure for any body area should be expressed as the
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product of the body surface area (see Table 2) and the appropriate
residue level expressed as micrograms of residue per square centi-
meter of exposure pad per hour of exposure. In cases where more
than one pad represents the area exposed, the mean of the residues
found on the appropriate pads should be used. As an example of
these calculations, assume that the residue levels for a person,
are as follows (in micrograms per square centimeter per hour):
right shoulder, 4; left shoulder, 2; back, 3; chest, 1; right
forearm, 8; and left forearm, 6; total dermal exposure for right
hand, 2,000 micrograms and for the left hand is 1,800 micrograms.
These data multiplied by the adult body surface areas in Table 2
gave the results shown in Table 3.
(5) Evaluation, (i) The study results should be reported as
the mean, plus or minus the standard deviation, of the exposure
found for each body area for each individual in the exposure
study.
(ii) Total dermal exposure should be reported in the same
manner for each individual and for the study group as a whole.
(iii) For calculations, exposure below the limit of detection
for the analytical method should be counted as 50 percent of that
limit.
(iv) The number of individuals in the study and all assump-
tions used in the calculations should be specified.
(v) The results should be reported without regard to dermal
absorption.
(f) References.
(1) Davis, J.E. 1980. Minimizing occupational exposure to
pesticides: Personnel monitoring. Residue Reviews 75:34-50.
[This review covers methodology for measurement of dermal exposure,
conduct of the studies, and conversion of residue levels to total
body dermal exposure.]
(2) Durham, W.F., and H.R. Wolfe. 1962. Measurement of the
exposure of workers to pesticides. Bull. World. Health. Org.
26:75-91. [This paper discusses methodology for measurement of
dermal exposure, conduct of the studies, and conversion of residue
levels to total body exposure. The skin surface areas listed in
Table 3 were taken from this paper.]
(3) Kahn, E. 1979. Outline guide for performance of field
studies to establish safe reentry intervals for organophosphate
pesticides. Residue Reviews 70:27-44. [This paper is primarily
concerned with information for development of human-subject, field-
study protocols for establishment of reentry intervals with organo-
phosphorus pesticides.]
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TABLE 1. PLACEMENT OF EXPOSURE PADS TO REPRESENT EXPOSED BODY AREAS.
Body area of concern Exposure pads representative of the body area
Face Right and left shoulder pads
Back of neck and back Back pad (upper center of the back)
Front of neck and chest Chest pad (upper center of the chest)
Upper arms Right and left shoulder pads and right and left
forearm pads
Forearms Right and left forearm pads (upper surface near
the midpoint of each forearm)
Thighs Right and left thigh pads (front of each thigh)
Lower legs Right and left ankle pads (front of each ankle)
TABLE 2. STANDARD BODY SURFACE AREAS
Body area Body Surface area (cm2)
Face ' 650
Back of neck 110
Front of neck plus "V" of chest 150
Chest and stomach 3,550
Back 3,500
Upper Arms 1,320
Forearms 1,210
Hands 820
Thighs 2,250
Lower Legs 2,380
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TABLE 3. EXAMPLE OF DERMAL EXPOSURE CALCULATIONS USING DATA GIVEN IN
§ 133-3(e)(4)
Exposed area
Face
Back of neck
Front of neck
Forearms
Hards
Total dermal exposure
Mean residue
(ug/on2/hr)
3
3
1
7
-
Skin area I/
(cm2)
650
110
150
1,210
-
Dermal exposure
(ug/hr)
1,950
330
150
8,470
3,800
14,700
I/ Skin areas taken from Durham and Wolfe (1962),
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§ 133-4 Measurement of inhalation exposure.
(a) Purpose. Data on inhalation exposure to airborne resi-
dues of a pesticide are required by 40 CFR § 158.140 to estimate
the amount of respiratory exposure during performance of an activ-
ity at a site. The data will then be used for the calculation of
reentry levels and reentry intervals as described in section series
134.
(b) When required. (1) Data on the estimated inhalation
exposure of humans are required to support the registration of a
product if:
(i) A reentry interval is required by 40 CFR § 158.140 [See
§ 130-3 of this subdivision]; and
(ii) The reentry interval is determined by the method described
in § 134-2.
(2) If the reentry interval for a use pattern is determined
by the non-detectable residue method described in § 134-1, then the
data requirements of this section do not apply.
(c) Combined testing. (1) Measurement of inhalation exposure
should be combined with measurement of dermal exposure, as described
in § 133-3, when both types of data are required. The applicant
should be certain that the standards for both types of testing are
met in the combined study.
(2) Measurement of inhalation exposure to a pesticide during
reentry into leafy crops should be combined with measurement of
dislodgeable foliar residues. Measurement of inhalation exposure
may be combined with tests discussed in this subdivision and other
subdivisions of these guidelines, such as Subdivision G (Product
Performance), Subdivision J (Hazard Evaluation: Nontarget Plants),
Subdivision N (Chemistry Requirements: Environmental Fate), and
Subdivision 0 (Chemistry Requirements: Residue Chemistry).
(d) Test standards. In addition to meeting the general test
standards contained in § 133-2(c), an inhalation exposure study
should also meet the following standards:
(1) Test substance. The applicant should use a typical end-
use product for this data requirement.
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43
(2) Preparations for tests. The specific sampling method,
sampling medium, and analytical procedure to be used will depend
on the material being studied, and are left to the discretion of
the investigator, provided they meet the standards prescribed in
this section.
(i) Sampling media. The specific sampling medium or media
to be used will depend on the compound to be sampled. Polyurethane
foam or a granular solid sorbent are generally recommended for
vapors. Pore sizes and mesh sizes should be selected to permit
appropriate airflow rates. Sorbents should be pre-extracted until
the extract contains no material which will interfere with subse-
quent analysis. The sorbents should then be dried and placed in
collection modules. If the sorbent does not adequately trap
dust, dusts should be collected with glass fiber or PVC membrane
filters placed in the collection module to follow the sorbent in
the air stream.
(ii) Sampling unit. Whenever possible, battery-powered per-
sonal air samplers should be used. If the expected pesticide lev-
els are below the limits of detectability by such low-volume air
samplers, then stationary high-volume air samplers should be used
instead.
(iii) Sampling efficiency. (A) Sampling efficiency of low
volume air-sampling pumps. The sampling efficiency of the sampling
unit and media should be demonstrated for the residues of interest
and reported data should be adjusted accordingly.
(B) Sampling efficiency of high-volume air-sampling pumps.
Both the retention and collection efficiencies for the combination
of sampler and sorbent should be determined with the residue of
interest. Whenever possible, tests should be performed outdoors
with unaltered ambient air; if necessary, intake air should be
filtered to remove interfering contaminants. At least one blank
•determination with unfortified filters should be made simultaneously
to correct for airborne interferences, contamination, or losses
through the analytical methodology.
(C) Standards for air-sampling collection efficiency. For
each test, at least five determinations should be made and the mean
and standard deviation for recovery of the original material deter-
mined. The mean recovery should be at least 75 percent.
(iv) Extraction method. The extraction efficiency of the
method chosen to extract residues from the sorbents should be deter-
mined or cited. Sorbent traps should be charged with the same
material and formulation to be studied and at approximately the
level expected to be collected during a sampling period in the
field study. At least five replicate samples should be extracted
and the mean and standard deviation for recovery determined. The
mean recovery should be at least 75 percent of the original material.
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44
(v) Analytical procedure. A study should be conducted or cited
to demonstrate that the analytical method chosen, coupled with the
sorbent and extraction method to be used, is capable of quantitative
detection of 0.5 ug/m^ or less of the compound being studied, or
of human exposure to 1 ug/hr or less of the compound when possible.
For applications involving material of very high toxic hazard, a
greater sensitivity may be required.
(vi) Stability of samples and extracts. (A) Stability of
exposed media. If sampling media are to be stored for longer than
24 hours after exposure, a test of stability of the residues of
interest while sorbed to the media should be conducted or cited.
Media should be charged with pesticide by the same procedure used
in paragraph (d)(3)(iii) of this section for sampling efficiency
testing. Lots of five replicate samples should be stored for at
least three different periods of time under the storage conditions
for field samples. The samples should be extracted and analyzed by
the methods to be used in field studies. The storage times should
be chosen so that the longest corresponds to the longest projected
storage period for field samples and so that a decay curve can be
constructed to allow extrapolation of residue levels back to the
time of collection. Storage of field samples should not exceed
periods that would result in loss of 50 percent or more of the
original residue.
(B) Stability of extracts. If extracts from field samples
are to be stored for longer than 24 hours before analysis, a study
should be conducted or cited that the demonstrates stability of the
compound of interest in the solvent to be used. Storage times
should be chosen so that the longest corresponds to the longest
projected storage period for extracts from field samples and so
that a decay curve can be constructed to allow extrapolation of
residue levels back to the time of extraction. Storage of extracts
from field samples should not exceed periods that would result in
loss of 50 percent or more of the residue originally extracted.
(vii) Calibration of air-sampling equipment. Sampling pump
airflow instruments should be calibrated for the particular sampling
medium to be used.
(3) Conduct of tests, (i) Positioning of sampling units.
If personal air samplers are used, the air intakes should be posi-
tioned to be at the height of the human breathing zone and should
be oriented downward or horizontally to avoid collection of non-
respirable particles or droplets. If stationary samplers are
used, the air sampling inlet should be positioned at the height of
the breathing zone of an average-sized person engaged in the desig-
nated task. Airflow through the sampling unit should be measured
at the beginning and end of each exposure period. If airflow changes
during the exposure period, the mean of these two measurements
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45
should be used as the airflow rate for calculations of air volume
sampled.
(ii) Handling of samples. Special care should be taken to
avoid contamination of the samples in the field. To avoid further
possible contamination, samples should be transported to the
laboratory in sealed containers. The containers should be chilled
or frozen to minimize residue losses in transit and storage.
(iii) Typical activities. The investigator should insure that
all activities contributing to the exposure being studied are
carried out in a manner consistent with typical use patterns of
the end-use product.
(iv) Application of the test substance. (A) Application
rates. Applications should be made at the maximum rate proposed on
pesticide labeling for the application method and site.
(B) Application method. The application method that causes
maximum residue levels should be used.
(v) Duration of exposure. The exposure period should be long
enough for measurable residues to be collected. Air should be
sampled throughout the period during which a person is expected to
be exposed to the pesticide in the selected maximum exposure
activity.
(e) Reporting of test results. Data should be compiled for
each exposure sample. These data sets should be indexed so that
the exposure data can be related to the residue levels. The
types of exposure data required may vary with the activity being
studied. An example of the types of data needed in particular
exposure situations are presented below as a guide:
(1) Exposure data. The following data, as appropriate to
the use type, should be reported:
(i) Test substance and formulation;
(ii) Description of test site, including crop, plot size,
row spacing, and height of crop;
(iii) Selected maximum exposure activity;
(iv) Investigator's name;
(v) Application rate;
(vi) Weather data, including relative humidity, wind con-
ditions (steady or gusty), speed and direction of wind, sun con-
dition (clear, partly cloudy, or overcast) and temperature;
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46
(vii) Height of sample unit intake;
(viii) Number of samples collected;
(ix) Length of exposure;
(x) Beginning and ending airflow rates; and
(xi) Any special situation observed that might alter normal
exposure.
(2) Analysis. Laboratory operations should be recorded on a
sample history sheet which includes:
(i) Storage methods and conditions for media and extracts;
(ii) The extraction and analytical procedures used; and
(iii) For each sample, the sample number and dates of collec-
tion, extraction, and analysis.
(3) Evaluation, (i) Estimates of inhalation exposure should
be reported for each individual sampling unit and for the group of
sampling units as a whole.
(ii) The mean and the standard deviation of the exposures
found for the group should be reported.
(iii) For calculations, exposure below the limit of detection
for the analytical method should be counted as 50 percent of that
limit.
(iv) The number of sampling units in the study and all assump-
tions used in the calculations should be reported.
(f) References. (1) Inhalation exposure studies require
procedures for the trapping, extraction, cleanup, separation,
and quantification of pesticides. Methods of those types and
associated information can be found in the following references:
(i) Adams, J.D., and J.H. Caro. 1980. Polyurethane foam as
trapping agent for airborne pesticides. EPA-600/4-80-008. (Avail-
able from NTIS, Springfield, VA 22161.) [This report contains
methodology for the evaluation of trapping media, for extraction
of trapped residues from the media, for clean-up and separation of
trapped residues by liquid chromatography, and for quantification
by GLC.J
(ii) Lewis, R.G. 1976. Sampling and analysis of airborne
pesticides. In: Air Pollution from Pesticides and Agricultural
Process. R.E. Lee (ed.) CRC Press, Inc. Cleveland, Ohio. pp.
51-94. [Reported methods for laboratory and field investigations
of pesticides in air can be found in this review.]
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47
(2) The following references nay be useful for the design and
interpretation of inhalation exposure studies.
(i) Davis, J.E. 1980. Minimizing occupational exposure to
pesticides: Personnel monitoring. Residue Reviews 75:34-50. [This
review covers methodology for measurement of inhalation exposure,
conduct of the studies, and conversion of airborne residue levels
to total inhalation exposure.]
(ii) Kahn, E. 1979. Outline guide for performance of field
studies to establish safe reentry intervals for organophosphate
pesticides. Residue Reviews 70:27-44. [This paper is primarily
concerned with information for development of human-subject, field-
study protocols to be conducted for establishment of reentry inter-
vals for organophosphorus pesticides.]
(iii) Lewis, R.G., M.D. Jackson, and K.E. Macleod. 1980.
Protocol for Assessment of Human Exposure to Airborne Pesticides.
Report EPA600/2-80-180. Available from the National Technical
Information Service, Springfield, VA 22161. [This report contains
discussions of methods for the quantification of airborne residues
in the worker environment and the conversion of airborne residue
levels to inhalation exposure levels.]
Series 134: CALCULATION OF REENTRY LEVELS AND REENTRY INTERVALS
§ 134-1 Non-detectable residue method.
(a) When used. For purposes of this section, a reentry inter-
val is that time period beyond which there are no detectable dis-
lodgeable residues of the pesticide on surfaces to which the pes-
ticide was applied, as indicated by studies conducted as described
in § 132-2 of this subdivision.
(b) Approach. Environmental samples may be collected period-
ically until no residues are detected in three consecutive samplings
using suitably sensitive analytical techniques and equipment. Al-
ternately, the applicant may be justified in extrapolating a dis-
sipation curve to the minimum detectable levels. The interval for
residue dissipation to the non-detectable level would then be pro-
posed as the reentry interval. For reentry intervals determined
according to this approach, exposure information described in
§§ 133-2, -3, and -4 are not required.
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48
§ 134-2 Allowable exposure level method.
(a) When used. For purposes of this section, a reentry inter-
val is that time period beyond which dislodgeable residues on surfaces
to which the pesticide was applied have dissipated to the allowable
exposure level (or lower) as indicated by studies described in
§§ 132-2, 133-3, and 134-1 of this subdivision.
(b) Approach. (1) Calculation of a reentry interval accord-
ing to the criteria of paragraph (a) of this section involves eval-
uation of data to determine that level of residue in a reentry site
which will result in an amount of human exposure under specified
human activities that is at or less than an allowable exposure
level. To make this evaluation, the applicant should use two kinds
of data:
(i) Data on the relationship between pesticide residue levels
and total human exposure during an eight-hour period; and
(ii) Data on the relationship between pesticide residue levels
and time.
(2) Figures 1 and 2 represent, in graphic form, the relation-
ships which will be evaluated.
(3) For the approach outlined in paragraphs (b)(l) and (2) of
this section:
(i) The applicant will determine an allowable exposure level
and described according to § 131-3, based on the toxicity data
required by 40 CFR § 158.135 and described by Subdivision F of these
guidelines.
(ii) The applicant will then examine human exposure data to
determine how much exposure (or what dose) a person would receive
when performing activities (specific to the proposed use) in a
treated area with specified levels of residues. (See Figure 1.)
These data will enable the applicant to determine a reentry level
(Rg) for a particular combination of human activity, crop, pesti-
cide formulation type, and site.
(iii) Finally, the applicant will review residue dissipation
curves to determine how long after application it will take the
residue levels to decline to the reentry level in the particular
study location, thus estimating the reentry interval (Ts). (See
Figure 2.)
(iv) The number of sampling units in the study and all assump-
tions used in the calculations should be specified.
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49
Figure 1. Estimation of exposure plotted against increasing levels of
pesticide residue
Human
Exposure
Level
AEL
Pesticide Residue Level
Rg = The Reentry Level is that residue level which will impart the dose
(AEL) during the course of a specified human activity in an eight-
hour period.
AEL = The Allowable Exposure Level, which is the no observable effect
level (NOEL) divided by an appropriate safety factor, appropriate
safety factor, according to § 131-3.
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50
Figure 2. Residue dissipation curve.
Log
Residue
Time
Rg = The Reentry Level, which is that residue level which will
impart the dose (AEL) during the course of a specified human
activity during an eight-hour period.
Ts = The Reentry Interval, which is the elapsed time after the com-
pletion of pesticide application at which the pesticide
residues (determined according to the methods specified in
section series 132) will have dissipated to the reentry resi-
due level (Rg).
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51
(c) References. The following paper used the AEL method for
determining a reentry interval.
(1) Iwata, Y., J.B. Knaak, G.E. Carman, M.E. Dtisch, and F.A.
Gunther. 1982. Fruit residue data and worker reentry research for
chlorthiophos applied to California citrus trees. J. Agric. Food
Chan. 30:215-222. [This paper reports dissipation data for a pest-
icide and its five toxic alteration products and uses that data to
estimate a reentry interval by the AEL and the CDFA methods. The
authors report that both methods give the same reentry interval.]
§ 134-3 Adjustment to reentry intervals.
(a) When used. A registrant or registration applicant may
provide information to support an adjustment of a reentry interval.
Such information should be of one of the types described in paragraphs
(b) through (d) of this section.
(b) Adjustments based on toxicity studies. The animal toxicity
studies described in Subdivision F may have been performed using
test substances of an end-use product or active ingredient in a
solvent. Solvents may aid in dermal absorption of the pesticides
and/or may increase their apparent toxicity. After application,
such components of end-use products may dissipate from the application
site more rapidly than the active ingredient. Testing of animals
with the pesticide without solvents may show that it is not as
toxic as the original product. If there are sufficient differences
in toxicity or in residue retention after application, the applicant
may wish to submit data to support adjustment of a reentry interval.
(c) Adjustments based on residue dissipation studies. In
some cases, established reentry intervals are based on data developed
from studies of a site that may not adequately characterize residue
dissipation at another site because of regional and climatological
differences, differences in application methods, or differences in
post-treatment methods and exposure. These factors would likely
affect the slope of the residue vs. time curve demonstrated in
Figure 2 of § 134-2(b). In such cases, additional data may be
submitted to the Agency to support an additional reentry interval.
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52
(d) Adjustments based on human exposure studies. Data fron
human exposure studies may indicate significantly different human
exposure levels because of widespread changes in agricultural practices
or other conditions. Such data may be submitted to support adjustment
of the reentry interval.
§ 134-4 Early reentry; practices and limitations.
(a) General. Local conditions and activities may necessitate
early reentry by individuals into treated areas before the reentry
period has completely elapsed. Such activities may include posting,
scouting, crop sampling, and similar related activities, often of a
brief and limited nature. Several practices may be necessary to
protect individuals who must undertake early reentry. Some of
these are described below. Consultation with local agricultural
experts is generally recommended before early reentry is undertaken.
(b) Reduction of site residues. Site residues may be reduced
to reentry level by rainfall or artificial means, such as spraying
the site with water. Data on residue reduction by rainfall or
equivalent spray washing (as in overhead irrigation) may be submitted
to support early reentry. In those cases, early reentry may be
granted to allow people to enter treated sites before expiration of
the reentry interval.
(c) Use of personal protective equipment. Early reentry may
be granted to allow people to enter treated sites before expiration
of the reentry interval by use of personal protective equipment,
such as protective clothing and appropriate respirators. The per-
sonal protective equipment should be appropriate for the pesticide
residue levels at the site at the time of reentry and should conform
to any existing protective standards (such as those established by
OSHA). Data on the reduction of human exposure to residues by use
of personal protective equipment should be submitted and support
that the personal protective equipment would reduce human exposure
to the allowable exposure level and would be likely to be used.
(d) Reduced exposure times. The reentry level is based on
residue exposures representative of normal reentry activities for
an 8-hour day. In circumstances where only respiratory exposure to
airborne residue will occur, early reentry may be allowed for shorter
periods at residue levels higher than the reentry level. The excur-
sion factors described in the Threshold Limit Values (TLV) booklet
of the American Conference of Governmental Industrial Hygienists
(ACGIH) may be used. Excursion factors allow shorter exposures to
chemicals at levels higher than the TLV or OSHA's Permissible
Exposure Limit. This approach requires that the exposure level be
within an acceptable excursion range and that the product of the
concentration multiplied by the exposure time does not exceed the
product of the TLV concentration multiplied by 8 hours. Such
excursion factors 'are applied only to chemicals which do not have
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53
established ACGIH "ceiling" designations. The ceiling designations
indicate that the TLV should not be exceeded.
(e) Residue level test kits. Early reentry may be allowed if
field test kits establish that residues have dissipated to reentry
level prior to expiration of the reentry interval. Data should be
submitted to support the use of field test kit systems for monitor-
ing pesticide residue levels. Such systems could include any of
several chemical residue detection devices or procedures that
would readily indicate when residue levels of treated sites are
greater or less than the allowable exposure level. (For this
factor, the adjustment could either extend or shorten the reentry
interval.)
(f) References. The following publications report procedures
for the analysis of organophosphorus pesticide residues in the
worker environment suitable for rapid tests in agricultural sites.
(1) Smith, C.A., F.A. Gunther, and J.D. Adams. 1976. Worker
environment research. III. A rapid method for the semiquantitative
determination of sane dislodgeable pesticide residues on citrus
foliage. Bull. Environ. Contain. Toxicol. 15:305-310. [This paper
reported the use of a device for sampling foliar surface residues,
and rapid methods for residue cleanup and quantification of organo-
phosphorus pesticide residues. The method depends upon the genera-
tion of a color by reaction with 4(4-nitrobenzyl)pyridine.]
(2) Smith, C.A., and F.A. Gunther. 1978. Rapid estimation of
organophosphorus pesticide residues in citrus grove soil. Bull.
Environ. Contain. Toxicol. 19:571-577. [A procedure for field
analysis of organophosphorus pesticide residues sorbed to surface
soil is reported in this paper.]
(3) Berck, B., Y. Iwata, and F.A. Gunther. 1981. Worker
environment research: Rapid field method for estimation of organo-
phosphorus insecticide residues on citrus foliage and in grove
soil. J. Agric. Food Chem. 29:209-216. [This paper is an elabora-
tion of the studies in references (1) and (2) (above) using differ-
ent sampling methodology and instrumentation. Procedures are
reported for both foliar and soil residues.]
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