The EPA author, John J. Streicher, who is on assignment from the National
Oceanic and Atmospheric Administration, U.S. Department of Commerce, is also
the EPA Project Officer (see below)

The complete report, entitled "Air Concentrations and Inhalation Exposure to
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EPA/600/SR-97/059 September 1997

SEPA

Project Summary

Air Concentrations and Inhalation
Exposure to Pesticides in the
Agricultural Health Pilot Study

John J. Streicher

The incidence of several types of can-
cers is higher among farmers than in
the general population—this despite
lower overall mortality. Occupational
agents responsible for these excess
cancers have not been definitively iden-
tified. The Agricultural Health Study
seeks to identify and quantify pesticide
exposures to farmers, indirect expo-
sures to their families, and to assess
health risks. A 6-farm, exposure pilot
study implemented a total exposure
assessment methodology, i.e., multime-
dia transport and multi-pathway expo-
sure. Sampling design included air in-
halation, oral ingestion, and dermal ab-
sorption. This paper reports on the air
transport and inhalation exposures
monitored during the exposure pilot
study. Meteorological data were col-
lected from an on-site three-meter
tower. Outdoor air was sampled on the
day of the pesticide application event,
and indoor air samples were collected
on three consecutive days centered on
the application day. Personal activity
logs, indicating time and location, were
maintained by participants during the
monitoring period. Of 33 targeted pes-
ticides, 7 were applied on at least one
of the participant farms, 11 were de-
tected in the outdoor air near a farm
residence, and 17 were detected in farm
residence indoor air. Indoor concentra-
tions of applied pesticides were de-
tected on 4 of the 6 farms, however
there is limited and conflicting evidence
to support an exclusively outdoor air
source of indoor concentrations of ap-
plied pesticides. Indoor concentrations
of non-applied pesticides were more
the rule than the exception. On 5 of the

6 pilot-study farms, concentrations of
non-applied pesticides were detected
in the indoor air sample on at least one
day. As expected, the applicator’s in-
halation exposure to applied pesticides
is greater than that of any other family
member on the day of application. For
spouse and children, the indoor mi-
croenvironment contributed to inhala-
tion exposure of pesticides to a far
greater extent than did the outdoor-on-
farm microenvironment—even on the
day of application.

This Project Summary was developed
by EPA's National Exposure Research
Laboratory, Research Triangle Park, NC,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).

Introduction

The incidence of several types of can-
cers is higher among farmers than in the
general population—this despite lower
overall mortality. Retrospective assess-
ments of exposure to any suspected toxin
are inadequate in determining environmen-
tal cause and health effect relationships.
The Agricultural Health Study (AHS) is
the first prospective study to evaluate the
role of pesticides in cancer risks to farm-
ers and their families. The AHS is a col-
laborative effort of the National Cancer
Institute, the U.S. Environmental Protec-
tion Agency, and the National Institute of
Environmenial Health Sciences. The study
seeks to identify and quantify pesticide
exposures to farmers, and indirect expo-
sures to their families, and to assess long-
term health risks.

&® Printed on Recycled Paper



A total exposure assessment methodol-
ogy was incorporated in the design of a 6-
farm exposure pilot study, i.e., multimedia
transport and multi-pathway exposure.
Thirty-three pesticides were targeted. Sam-
pling design included air inhalation, oral
ingestion, and dermal absorption. Media
and cohort monitoring were chronologi-
cally centered around farm pesticide ap-
plication events. Baseline concentrations
of pesticides were considered in sampling
during a non-application (i.e., control) sea-
son, vs. the application season. This pa-
per reports on the air transport and inha-
lation exposures monitored during the pi-
lot study. Applicator, spouse, and up to
two children participated from four lowa
and two North Carolina farms.

Air and Inhalation Exposure
Monitoring Procedures

The assessment of direct inhalation ex-
posure of the applicator during application
events (handling, mixing, and loading
(HML) operations; as well as actual pesti-
cide application) required concurrent sam-
pling of the applicator’s breathing zone.
Assessment of indirect inhalation expo-
sures, as may be accrued by all family
members from breathing indoor or out-
door air contaminated with fugitive pesti-
cides, required sampling of indoor and
outdoor air. All samples were collected
with a polyurethane foam (PUF) and quartz
pre-filter cartridge with a size-selective im-
pactor at cartridge inlet which removed
particles greater than 2.5 micrometers in
diameter.

A five-day sampling strategy was chro-
nologically centered on the day of a
planned application event, hereafter syn-
onymous with “day 3”. The first and fifth
days were directed toward setup and dis-
assembly of monitoring equipment. Dur-
ing the second, or pre-application day, an
indoor air sample was collected. During.
the application day, indoor and outdoor
air samples were collected, as well as
personal air samples from the applicator.
During the fourth, or post-application day,
an indoor air sample was collected. Par-
ticipants’ activity logs recorded the time,
location, and activity of the applicator,
spouse, and one or two children, during
days 2, 3, and 4.

A personal air sampler measured the
applicator’s exposure to pesticides by in-
halation during HML and application ac-
tivities. A 3.8 L/min air sample was drawn
through an inlet tubing positioned within
the applicator’s breathing zone. A meteo-
rological monitoring tower collected wind
speed, wind direction, temperature, and
relative humidity data at 3 meters above

ground level. Outdoor air pesticide con-
centrations sampled at the residences on
the application day were expected to cor-
relate with pesticide spray drift during ap-
plication if meteorological conditions fa-
vored such transport. The indoor air
samples, collected on days 2, 3, and 4, in
conjunction with participant activity logs,
provided data for indirect exposure as-
sessment of all family members. A non-
application season indoor air sample pro-
vided indication of baseline concentrations
and chronic exposure. Indoor and outdoor
samples were 24-hour averages; applicator
personal air samples were collected over the
duration of the activity of interest—either HML
or application.

Modeling Initiative

The contribution of modeling in this study
was to estimate potential peak outdoor
concentrations under hypothetical near
worst case conditions. The selection of
application events suitable to a physically
based model simulation was based on
both model capability and data limitations.
Each simulated case adheres to actual
pesticide amounts applied and rate of ap-
plication. However, meteorological condi-
tions were a conservative composite of
measured variables, and concentrations
are calculated at plume centerline (i.e.,
assuming wind direction is directly from
application field to monitor). Meteorologi-
cal data are reported for selected farms
concurrent with monitored application
events.

The AgDRIFT model was initially devel-
oped to assess off-target drift deposition
rates of water-based aerial pesticide ap-
Plications. It can also calculate plume
centerline concentrations needed in the
assessment of inhalation exposure. At the
model’s core is a Lagrangian treatment of
dispersion, tracking each nozzle stream
of droplets through a flow field. AgDRIFT
incorporates source constructs such as
nozzle type, flow rates, and drop size dis-
tribution. Environmental variables having
greatest impact on transport—wind speed,
temperature, and relative humidity—are
incorporated in AgDRIFT’s calculations.
AgDRIFT was deemed suitable to simu-
late ground boom sprayer drift, provided
several extrinsic source parameters are
appropriately assigned.

The application of the AgDRIFT model
to ground boom spraying was accom-
plished by the appropriate setting of vari-
ous emission and dispersion variables. The
objective of the modeling exercise was to
provide conservative assessments of
downwind concentrations of applied pesti-
cides for an averaging time typical of ap-

plication duration. The actual application
rate (pounds active ingredient applied per
acre and per unit time) was adhered to in
the calculations. Model simulations were
consistent with measured values of wind
speed during actual application periods.
Quantitative details of pesticide applica-
tion are reported, including pesticide iden-
tification, amount of active ingredient, to-
tal’ volume of liquid mixture applied, the
concentration, acreage of application, ap-
plication rate, duration of the application,
and distance to the receptor (i.e., farm
house). Additionally, the model estimate
of worst case peak concentration at the
receptor is reported, as is the “24-hour
averaged” model calculation, and finally
the measured 24-hour average concen-
tration. Figures illustrate modeled peak
one-hour concentration, at nominal adult
breathing height (1.5 m), as a function of
downwind distance.

Results and Discussion

Indoor and outdoor monitored concentra-
tions of all detected pesticides are presented
by farm, for both contro! (non-application) sea-
‘son, and application season. Indoor concen-
trations of an applied or residual pesticide
were higher on the application day than con-
terminous days on lowa farm #1 (dicamba),
lowa farm #2 (metolachlor), and lowa farm #3
(alachlor; second application season). How-
ever, the cases observed in the pilot study do
not strongly support a conclusion that outdoor
air (exclusively) is the source of indoor con-
centrations of applied/residual pesticides.

The time, location, and activity of study
participants were recorded by the partici-
pants during days 2, 3, and 4. These activ-
ity logs were reviewed with respect to par-
ticipant location (and activity, in the case of
HML or application). To assess exposure
to detected pesticides, participant location
was partitioned by characterized microen-
vironments (indoors; outdoors on farm; or
performing HML/application activity), and
time-in-microenvironment exposure was
accumulated within 24-hour periods.

Applicator exposures represented the pre-
ponderance of the applied pesticide inhala-
tion exposure of any family member on any
AHS farm on the day of application. Appli-
cators generally used no respiratory pro-
tection during HML or application activity.
Not surprisingly, HML and application ac-
tivities accounted for nearly all of the
applicator’s day 3 exposure to the applied
pesticide. Applicator exposure from HML/
application activity is presented as a per-
centage of day 3 total exposure. Applicator
exposure during HML/application activities
accounted for between 80% (alachlor on
North Carolina farm #1) and 100%


(dicamba and 2,4-D butoxy ethy! ester on
lowa farm #2) of applicator day 3 expo-
sure to applied pesticides. A summary of
applicators’ day 3 HML/application—re-
lated dose was also calculated with an
estimated 25 liters per minute [L/min]
breathing rate.

Inhalation exposures of all family mem-
bers on the application day were calcu-
lated to assess relative exposure of appli-
cator, spouse, and children. Application
day air pathway exposures are presented
by farm, applied pesticide, family mem-

ber, and by microenvironment. The data ©

are presented to permit attribution of a
family member’s exposure to each of the
three designated microenvironments (i.e.,
HML/application activities, outdoors on
farm, and indoors). When personal air
samples distinguished multiple HML/ap-
plication activities, separate exposures are
calculated. The final column in each table
provides the sum of exposures accrued in
all microenvironments on the application
day, by family member and applied pesti-
cide.

The indoor microenvironment is unique
in its contribution to pesticide exposure of
all study participants via the air pathway.
Time-activity logs indicated that all partici-
pating family members at all farms spent
an average in excess of 8 hours per day
indoors, over the three-day period. In all
cases except lowa farm #4, concentra-
tions of at least one pesticide being ap-
plied, or found as residue within the appli-
cation mixture, were measured indoors
during the three-day monitoring period.
Numerous examples of non-applied, non-
ambient (no detectable outdoor concen-
tration), pesticides were found to be
present in indoor air samples. Indeed, in-
door concentrations of non-applied pesti-
cides were the rule more than the excep-
tion.

Indoor air exposures and inhalation
doses of all indoor detected pesticides—
regardless of their known origin on the
farm, are presented for all participants, by
farm, pesticide, and day. The three-day
exposure sum, as well as a mean daily
indoor inhalation dose, is also calculated
in the final columns of each table. A rest-
ing breathing rate of 10 L/min was applied
to exposure sums in calculating inhalation
dose.

Summary and Conclusions

Of the 33 targeted pesticides, 7 were
applied on at least one of the participant
farms, 11 were detected in the outdoor air
near a farm residence, and 17 were de-
tected in farm residence indoor air.

The pesticide applicator was usually ex-
posed to the applied pesticide(s) during

HML and application activities. An excep-
tion was found on: lowa farm #4, where
pyrethrins and. piperonyl :butoxide were
applied but their presence in personal air
samples was not detected. While the
applicator’s inhalation exposure to applied
pesticides occurs almost exclusively dur-
ing HML/application activities (at least
80%), exposure to non-applied (fugitive)
Pesticides does occur during time spent
outdoors on the farm, and even more so
during time spent indoors.

Outdoor concentrations of pesticides
applied using a ground boom sprayer were
detected (stationary point measurement)
at significant concentrations (265 ng/m®
alachlor, 24-hour average, on North Caro-
lina farm #1) when wind direction favored
such transport. The converse is not sup-
ported, however, as oiitdoor concentra-
tions of atrazine were detected on lowa
farm #3 even though wind direction never
favored source-to-receptor transport dur-
ing HML or application activities. Outdoor
concentrations of non-applied pesticides
were detected on 5 of the 6 farms. The
highest 24-hour outdoor concentration of
any non-applied pesticide was 26.3 ng/m*
metolachlor on lowa farm #3 during the
first application season, although
metolachlor was found residual within the
applied pesticide mixture. The highest 24-
hour outdoor concentration of any non-
applied, non-residual pesticide was 18.7
ng/m® alachlor, also detected on lowa farm
#8 during the first application season. Pes-
ticide application events can substantially
increase outdoor concentrations directly
downwind—to levels exceeding typical ap-
plicator personal air concentration during
handling, mixing, and loading. Elevated
outdoor pesticide concentrations were not,
however, clearly related to indoor concen-
trations on farms monitored in this study.

Indoor concentrations of applied pesti-
cides were detected (stationary point mea-
surement) on 4 of the 6 farms, although
one case (metolachlor on lowa farm #2)
confirmed detection during the control sea-
son as well. Indoor concentrations of an
applied or residual pesticide were higher
on the application day than conterminous
days on lowa farm #1. (dicamba), lowa
farm #2 (metolachlor), and lowa farm #3
(alachlor; second application season).
However, the cases observed in the pilot
study do not strongly support a conclu-
sion that outdoor air (exclusively) is the
source of indoor concentrations of applied/
residual pesticides. Indoor concentrations
of. non-applied pesticides were more the
rule than the exception. On 5 of the 6 pilot
study farms, concentrations of non-applied
pesticides were detected on at least one

day. In most cases, applicator/spouse
questionnaires relating to historical use of
such pesticides could not confirm usage.

The applicator’s inhalation exposure to
applied pesticides is greater than that of
any other family member on the day of
application (calculated exposures indicated
applicator inhalation exposure to be at
least a factor of 5 times greater). This
elevated exposure is attributable to HML/
application activities. Non-applicator fam-
ily members can be exposed indirectly to
applied (and non-applied) pesticides dur-
ing time spent indoors or outdoors on the
farm. For spouse and children, the indoor
microenvironment contributed to inhalation
exposure of pesticides to a far greater
extent than did the outdoor-on-farm mi-
the day.of ap-.,
Is, mean daily
indoor inhalation dose for a spouse or
child was calculated to be on the order of
micrograms—comparable to doses re-
ceived by an applicator during an applica-
tion (although toxicological response and
health risk cannot be presumed to be the
same). This importance of the indoor mi-
croenvironment to an individual's total in-
halation exposure is attributable to sev-
eral factors. Firstly, the time spent indoors
(over the course of 24 hours) exceeded
time spent outdoors on the farm. Chronic
exposure to pesticides found in farm resi-
dence indoor air can be comparable, in
cumulative inhaled dose, to exposures ac-
crued by applicators during pesticide ap-
plications. Secondly, pesticide concentra-
tions were generally higher indoors than
outdoors (of 20 comparisons that could
be made, 14 pesticides had higher 24-
hour indoor concentrations; only 6 had
higher 24-hour outdoor concentrations).
Thirdly, the indoor microenvironment con-
tained a greater number of detected pesti-
cides than outdoors (17 different pesti-
cides. were’ detected in indoor -samptes;
11 were detected in outdoor samples).

Disclaimers

This paper has been reviewed in accor-
dance with the United States Environmen-
tal Protection Agency’s peer review and
administrative review policies for approval
for presentation and publication. Mention
of trade names or commercial products
does not constitute endorsement or rec-
commendation for use. The information in
this document has been funded by the
National Institutes of Health and the United
States Environmental Protection Agency.
It has been subject to review by the Na-
tional Cancer Institute and National Insti-
tute of Environmental Health Sciences and
approved for publication.