[PDF](+47👁️) Télécharger DTIC ADA129253: An Evaluation of Filter Effectiveness for Removing Airborne Chlordane in Crawl Space Houses at McConnel AFB, Kansas pdf
A study to determine the effectiveness of polyurethane filters to remove chlordane from the air was performed in crawl space houses at McConnel AFB. The soil around and under the houses was treated with a 1% chlordane emulsion in 1974 and 1979. The ventilation ducts are located in the crawl space. Although the filter did adsorb chlordane, most airborne chlordane measurements in the study houses were above 5 micron/m3. The National Academy of Science has established 5 micron/m3 as a guideline for houses. A direct correlation between chlordane concentration and outside crawl space temperature was observed.Télécharger gratuit DTIC ADA129253: An Evaluation of Filter Effectiveness for Removing Airborne Chlordane in Crawl Space Houses at McConnel AFB, Kansas pdf
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AN EVALUATION OF FILTER EFFECTIVENESS FOR
REMOVING AIRBORNE OLQRDANE IN CRAWL SPACE
HOUSES AT MCCONNELL AFB KS
DECEMBER 1962
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DTIC
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4 1983
DISTRIBUnON STATEMENT A
Approved far public release;
Distribution Unlimited
USAF Occupational and Environmental Health Laboratory
Aerospace Medical Division (AFSC)
Brooks Air Force Base,Texas 78235
83 06 13 122
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available to the general public, including foreign nations.
This technical report has been reviewed and is approved for publication.
WILLIAM E. MABSON, Colonel, USAF, BSC
Commander
UNCLASSIFI
SECURITY CLASSIFICATION OF This PACE Data En(«r«<J)
REPORT DOCUMENTATION PAGE
4. TITLE (and Subtitle)
AN EVALUATION OF FILTER EFFECTIVENSS FOR
REMOVING AIRBORNE CHLORDANE IN CRAWL SPACE
houses at McConnell afb ks
READ INSTRUCTIONS
BEFORE COMPLETING FORM
3. RECIPIENT'S CATALOG NUMBER
5. TYPE OF REPORT A PERIOD COVERED
FINAL 1 Jon—15 Sep 1982
6. PERFORMING ORG. REPORT NUMBER
7. AUTHORS M)
8. contract or grant numbers
EDWARD S. BARNES, Major, USAF, BSC
9. performing ORGANIZATION name and aodress
USAF Occupational and Environmental Health
Laboratory, Brooks AFB TX 78235
10. PROGRAM ELEMENT, PROJECT TASK
AREA 8 WORK UNIT NUMBERS
II. CONTROLLING OFFICE NAME ANO AODRESS
USAF Occupational and Environmental Health
Laboratory, Brooks AFB TX 78235
12. REPORT DATE
December 1982
13. NUMBER OF PAGES
18
14. MONITORING AGENCY NAME 8 AODRESSfff dillarant from Controlling Office) IS. SECURITY CLASS, (of thla report)
UNCLASSIFIED
ISe. DECLASSIFICATION DOWNGRADING
SCHEDULE
18. DISTRIBUTION STATEMENT tot thla Ftapon)
Approved for public release, distribution unlimited.
17. DISTRIBUTION STATEMENT (of tba abatract entered In Block 20, it dUfarant from Report)
19. KEY WORDS (Continue on ravaraa side it necessary and identify by block number)
Chlordane
polyurethane filters
termite treatment
crawl space houses
family housing
20. ABSTRACT (Continue on ravaraa aide It necessary and Identify by block number)
study to determine the effectiveness of polyurethane filters to remove
chlordane from the air was performed in crawl space houses at McConnel AFB.
The soil around and under the houses was treated with a 1% chlordane emulsion
in 1974 and 1979. The ventilation ducts are located in the crawl space.
Although the filter did adsorb chlordane, most airborne chlordane measurements
in the study houses were above 5 pg/m». The National Academy of Science has
established 5 pg/m* as a guideline for houses. A direct correlation between
chlordane concentration and outside crawl space temperature was observed.*^—
DO I ja£ M ?3 1473 COITION OF I NOV 89 IS OBSOLETE UNCLASSIFIED
UNCLASSIFIED
SECURITY CLASSIFICATION OF THIS PAGE -Whan Data Entarad)
REPORT NO. S3-069EH118MPB
OSAF OCCUPATIONAL AND ENVIRONMENTAL
HEALTH LABORATORY
BROOKS AFB TX 78235
AN EVALUATION OF FILTER EFFECTIVENESS FOR
REMOVING AIRBORNE CHLORDANE IN CRAWL SPACE
houses at McConnell afb ks
DECEMBER 1982
Prepared by:
c
EDWARD S. BARNES. Major. USAF, BSC
Consultant, Industrial Hygiene Engineer
Reviewed by:
C fe'
ARTHUR P. CALDWELL, Colonel, USAF, BSC
Chief, Consultant Services Division
Approved by:
(^Y
JOHAN E. BAYER, Colonel, USAF, BSC
Vice Commander
TABLE OF CONTENTS
PAGE
List of Illustrations ii
I. INTRODUCTION 1
II. BACKGROUND 1
A. General 1
1. Chi or da ne Information 1
2. CAlordane Toxicity 2
3. Exposure Standards 2
B. McConnell AFB 3
1. Bousing Construction 3
2. Termiticide Treatment 3
3. Initial Survey Results 4
4. Proposed Corrective Actions 4
III. POLYURETHANE FILTER STUDY PROTOCOL 4
A. Experimental Design 4
B. Sampling and Analytical Techniques S
C. Observations 5
IV. RESULTS 6
V. DISCUSSION 6
VI. CONCLUSIONS 12
VII. RECOMMENDATIONS 13
References 14
Distribution 15
i
LIST OF ILLUSTRATIONS
FIGURE PAGE
1 Pre-filter installation chlordane concentration versos filter 9
chlordane loading
2 Control booses chlordane concentration versos crawl space 10
temperatore.
TABLE PAGE
1 Air sample and filter loading data 7
2 Environmental conditions doring sampling 8
3 Temperatnre data - McConnell AFB 12
Accession For
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I. INTRODUCTION
Hie USAF OEHL has been investigating the presence of airborne chlordane in
military family honsing units located on USAF installations at the request of
the AF Medical Service Center (AFMSC). All houses surveyed were constructed
on soil which had been treated with chlordane as a subterranean termite pre¬
ventative measure. The initial USAF OEHL effort was directed at houses con¬
structed on a concrete slab with ventilation ducts in or below the slab.
Houses treated with chlordane before and/or after construction were evaluated.
Chlordane intrusion into the living area of the housing units was found in
both houses treated prior to construction (1) and those treated after con¬
struction (2).
In March 1981. McConnell AFB KS, under the direction of the AFMSC, sampled
five houses of the basement/crawl space design for ambient chlordane levels.
The ventilation ducts were located in the crawl space and the crawl space soil
had been treated with chlordane. The air samples yielded chlordane. This
was the first indication of chlordane intrusion into this type house. Twenty-
seven percent of the crawl space houses at McConnell AFB yielded chlordane
levels exceeding the established guideline. Of the many methods evaluated to
reduce chlordane levels in these housing units, a polyurethane filter in¬
stalled in the ventilation system showed the greatest promise from a perfor¬
mance and economic standpoint.
II. BACKGROUND
A. General
1. Chlordane Information
Chlordane is a member of a group of chlorinated hydrocarbon insec¬
ticides generically termed "chlorinated cyclodienes." It is colorless and
odorless. The chlorinated cyclodieaes—chlordane, aldrin, dieldrin and
heptachlor—are the principal pesticides used for control of subterranean
termites. Chlordane has been extensively used in the U.S. for agricultural
and household pest control since 194S. The U.S. Air Force, other DOD agencies
and the civilian community have employed chlordane as the principal pesticide
for subterranean termite control.
In December 1975, the Environmental Protection Agency (EPA) sus¬
pended the use of chlordane in the U.S, with the exception of fire ant con¬
trol, subterranean termite treatment, and the dipping of roots and tops of
nonfood plants. Chlordane application for fire ant control was suspended by
EPA in December 1980. The suspension was based upon the persistence of chlor¬
dane in the environment and the discovery of its degradation product, hepta¬
chlor epoxide, in food, human tissue and wildlife. Persistence is an attri¬
bute of many chlorinated hydrocarbons and cyclodienes can be effective as
termiticides up to 20 years after application. Approximately 20% of original¬
ly applied chlordane dosages are recoverable in soil ten years after applica¬
tion. Consequently, the probability for organism exposure to chlordane and
the potential for bioaccumulation and biomagnification is greatly enhanced.
1
2. Chlordane Toxicity
Chlordane can be absorbed throngb inhalation, ingestion or dermal
contact.
EPA cited resnlts of experiments with rats and mice shoving signi¬
ficant increases in cancerous tumors caused by heptachlor epoxide, a metab¬
olite of chlordane. The tumors were found in several organs of these experi¬
mental animals, including the liver and other endocrine glands. The EPA also
noted evidence indicating that heptachlor epoxide in humans is transferred
from the mother to the fetus across the placenta. A more recent study by the
National Cancer Institute (NCI) concluded that chlordane concentrations of 40
parts per million (ppm) and higher in the feed of mice caused a significant
increase in liver cancer. In contrast, hepatocellular carcinomas failed to
appear at a significant incidence in rats. Central nervous system effects—
hyperexcitability, tremors and convulsions—have also appeared in laboratory
animals fed various cyclodiene class termiticides.
Limited human studies involving chronic long-term exposure to
chlordane have been confined to the occupational setting. They have not
revealed any consistent or significant detrimental effect from exposure to
chlordane (3). An examination of workers exposed to 1.2 to 1.7 micrograms per
cubic meter (|ig/m*) for 1-15 years showed no job-related illness among the
workers (4). A similar conclusion was given following a study of workers
exposed to 10 milligrams of chlordane per cubic meter of air (mg/m*) for three
years (5).
A statistical evaluation of death records for individuals employed
in the manufacture of chlordane noted a significant excess of deaths from
cerebrovascular disease, but the researchers emphasized that this should not
be accepted as evidence of a consequence of exposure to chlordane without
further study(6).
A recent epidemiological study of workers producing chlordane
concluded that there was no evidence to indicate that current or past workers
are at an increased risk for health related problems. However, the sugges¬
tion of a trend in cancer deaths with duration of employment indicates that
more complete data are needed before firm conclusions can be reached with
regard to the carcinogenicity of chlordane in humans (7).
3. Exposure Standards
The American Conference of Governmental Industrial Hygienists
(ACGIH) 1982 has adopted a threshold limit value-time weighted average (TLV^~
TWA) of 0.5 mg/m* for chlordane in workroom air (8). This is the maximum
allowable level to which it is believed workers may be continuously exposed in
the occupational environment (8 hours/day, 5 days/week) without adverse ef¬
fect. The short-term exposure limit (STEL) was set at 2 mg/m*.
The Occupational Safety and Health Administration's (OSHA)
permissible workplace exposure limit is also 0.5 mg/m*. Both agencies noted
that chlordane is absorbed through the skin and that dermal exposure should,
therefore, be avoided.
2
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T-aV.tfiw
Cognizant that neither the ACGIH nor OSHA criteria were applicable
to the home environment because of increased exposure tine and a significantly
different population involved, the USAF requested the National Acadeay of
Science (NAS) to provide guidance.
In 1979, the NAS Committee on Toxicology concluded that it "could
not determine a level of exposure to chlordane below which there would be no
biologic effect of prolonged exposure of families in military housing." How¬
ever, it did suggest an interim airborne concentration of 5 ng/m*• The guide¬
line was pragmatically determined on the basis of known concentrations of
chlordane in military housing, a review of reported health complaints of
residents of contaminated housing, and a comparison with the acceptable daily
intake derived from long-term animal feeding studies. The NAS Committee on
Toxicology concluded in an August 1982 report that there was no new data to
justify a change in the S jig/m* guideline (3).
In 1980, EPA initiated a formal risk-benefit review of chlordane
to determine whether its registered uses for subsurface termite control should
be limited or canceled, and whether the health of people living in houses
treated with chlordane is being adversely affected. To date, EPA has not
published its findings.
B. McConnell AFB
1. Housing Construction
There were 485 housing units constructed on McConnell AFB in 1959
using a partial crawl space and partial basement design. Nine different floor
plans exist for this type house and the crawl space may be located below
bedrooms or common living areas of-Uie house dependent upon the floor plan.
The furnace and ventilating system are located in the basement, and the supply
and return air ductwork is in the crawl space. The return air ducts are
formed using the wooden floor joists and sheet metal to shape an air chamber.
Supply air is routed to floor registers through sheet metal ducting.
2. Termiticide Treatment
All 485 crawl space units were treated with 1% chlordane water
emulsion in 1974 and 1979. The houses were retreated in 1979 because the high
number of in-house treatments required in the interim years (62 total) indi¬
cated the 1974 treatment was not adequate to suppress termite infestation.
The 1979 treatment consisted of applying chlordane around all building exteri¬
or perimeters by rodding, by holes drilled through concrete slabs, through
holes drilled in the brick veneer, by saturation of the soil in the crawl
spaces adjacent to foundation walls and support piers, some by saturation of
the wood sill surface in the crawl spaces, and by drilling holes through the
concrete slabs supporting block walls which support wood structures (such as
carport roofs).
3
3. Initial Survey Results
Initial air sampling in the 483 housing units was accomplished
during September and October 1981. The number of units found to equal or
exceed 3 pg/m* vas 129, or 27% of the total. The highest concentration
measured was 43 pg/m 1 and only four samples were nondetectable (ND). The
remaining 332 samples varied between ND and 3 (ig/m*.
4. Proposed Corrective Actions
In November 1981, five engineering modifications developed to
reduce chlordane concentrations in nine housing units were undertaken.
The modifications included: positioning fiberglass insulation
between floor joists, sealing and painting basement walls, laying a plastic
cover over crawl space soil, installing a positive ventilation system in the
crawl space, and putting a plastic cover between floor joists. Although test
results of these five different modifications proved inconclusive, cleaning
and sealing of air ducts, included as part of all modified quarters, appeared
effective in reducing chlordane levels. Duct cleaning entailed vacuuming
accomplished by a contractor. Contractor performance was not supervised.
During February-March 1982, polyurethane foam filters installed in place of
normal furnace filters were tested as another technique to reduce chlordane
concentration. A North Carolina State University research team had reported
polyurethane filter use to collect chlordane. The preliminary filter study in
four houses at McConnell AFB indicated that the filters showed promise as a
means to reduce chlordane concentrations in the crawl space houses. A more
extensive OSAF OEHL-sponsored study of the polyurethane filter ensued.
III. POLYURETHANE FILTER STUDY PROTOCOL
The objective of the study was to evaluate the effectiveness of a 1/4 inch
polyurethane filter and to determine the frequency of filter replacement
Representatives from HQ AFMSC/SGPA, HQ USAF/LEEV, HQ SAC/SGPB and DEMM,
MConnell AFB personnel and the USAF OEHL participated the protocol
development.
A. Experimental Design
Twenty houses were used for the study. All houses had partial crawl
space/partial basements and a similar layout (e.g., basement below living room
in all houses). Duct cleaning was accomplished in all houses involved in the
study prior to filter installation. The 20 houses were divided into four
groups of five houses; a control group and 30, 60 and 90 day filter groups.
Only the control houses remained unoccupied throughout the evaluation. All
houses were sampled at approximately the same time. Two samples were collect¬
ed from all the houses prior to the installation of filters. Polyurethane
foam filters were installed in 13 test houses and one air sample collected
from each house every 13 days for the first month. The filters were then
removed from five houses at the end of the first month. The remaining 13
houses were sampled every 13 days for the second month; the filters were then
4
removed from another five houses after the second month. The remaining ten
houses were sampled every 15 days for the third month; the filters then were
removed from the final five houses. All control houses remained in the sam¬
pling program throughout the three-month study.
B. Sampling and Analytical Techniques
Every attempt was made to control sources of variability during
sample collection. Time of day. pomps, and pump location were considered.
R
The basic sampling train consisted of an electric Millipore miniature
vacuum pump with a SKC sampling tube containing Chromosorb tt 102 as the
collecting medium. The sampling tubes were connected to the pump by a small
piece of Tygon^ tubing. Flow rates were measured using a Gilmont precision
rotameter after the pump was turned on and again at the end of the sampling
period. The rotameter was calibrated prior to the survey with a bubble meter.
In instances where a slight drop in flow rate occurred, the beginning and
ending flow rates were averaged to obtain a mean flow rate. The flow rates
were appoximately 4.0 liters per minute for all samples.
The same pump was used in the same location in a given house
throughout the evaluation. The pump and Chromosorb tube were located 3 ft off
the floor in the center of the living room.
The following conditions were also recorded during the sampling
period: inside temperature and relative humidity; outside high temperature,
low temperature and barometric pressure; soil temperaturr and ambient temper¬
ature in the crawl space. __
Samples were submitted to the USAF OEHL every 15 days for analysis.
The filters, removed after 30, 60 and 90 days, were also submitted to the
0SAF OEHL for analysis. The samples were analyzed according to methods
established by Thomas and Seiber (9) and Thomas et al (10).
Soxhlet extraction with hexane was used to recover chlordane from the
filters.
C. Observations
1. Following completion of the sampling outlined in the study
protocol, the Environmental Health Service at McConnell AFB performed
additional sampling for chlordane. A polyurethane filter was installed in the
five control houses. After seven days, the house was sampled and the filters
removed. These samples and filters were also forwarded to the USAF OEHL for
analysis.
2. The total sampling effort included 135 air samples and 20 filter
samples.
5
IV. RESULTS
Table 1 shows a compilation of chlordane concentrations measured in the
study houses and chlordane loading found on the polyurethane filters. Hie
amount of chlordane on the filters was measured in milligrams of chlordane per
gram of filter material (mg/G). Table 2 shows the environmental conditions
under which the samples were collected.
V. DISCUSSION
The filter loading data from Table 1 clearly show that the polyurethane
filter removes chlordane from the air being circulated through the housing
units. However, the period of time filters should remain in place for optimum
effectiveness is difficult to predict. Although the mean filter loading
increased to 9.1 mg/G through the 60 days, mean loadings of 7.8 mg/G and 8.0
mg/G at 7 and 30 days, respectively, are not significantly different. The
mean filter loading of 5.9 mg/G at 90 days is considerably less than the other
filters and is unexplainable. The data show that the polyurethane filters
continue to adsorb chlordane up to 60 days after installation. However, this
should not be interpreted to mean that the effectiveness of the filter
increases up to the 60 day point. Hie data essentially demonstrate that opti¬
mum filter effectiveness may be less than 7 days because of the insignificant
increase in filter load after that time in place.
There appears to be little correlation between chlordane concentrations
measured prior to filter installation versus the filter loading in the
respective houses. Figure 1 shows a plot of these data. The correlation
coefficient (r), which measures the strength of relationship between air
concentration and filter load, was~T5.2325. An r of 1.0 shows a perfect linear
relationship between two variables and an r = 0 means the two variables are
not correlated.
The preliminary filter evaluation done in February to March 82 yielded a
mean recovery of 4.6 mg chlordane per gram of filter. These filters remained
installed 9-27 days. The recovery from these filters was considerably less
than the filters removed after 7 days in the latest study and may be a func¬
tion of the ambient temperatures which were warmer during the filter protocol
study, causing increased chlordane emission from the soil and greater filter
loadings.
A direct relationship between air temperature in the crawl space and
chlordane concentration was indicated in the control houses, see Figure 2.
Correlation coefficients for the five control houses ranged from 0.72 to 0.93,
with a mean correlation coefficient of 0.82. Ambient outside temperatures
also show a direct relationship with airborne chlordane concentrations and is
6
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Figure 1
CONCENTRATION <UE/M3>
CONTROL HOUSES
CHLORDRNE CDNCENTRRTI ON
VERSUS
CRRWL SPRCE TEMPERRTURE
TEMPERRTURECT 5
Figure 2
10
J
to be expected because outside temperature greatly influences crawl space
temperature. Previous air samples collected in tbe control houses further
corroborate this relationship:
(1)
2913
Andrews
19
Feb
82
59®F
6
sample
mean
=
2.1
P3/®*
(2)
3033
Fairchild
18
Feb
82
49 # F
6
sample
mean
=
3.5
pg/m*
(3)
8229
Tinker
19
Feb
82
44®F
6
sample
mean
=
1.0 pg/m*
(4)
3013
Westover
17
Feb
82
38 # F
6
sample
mean
a
3.5
pg/m*
(5)
2909
Westover
22
Feb
82
73®F
6
sample
mean
a
2.8
pg/m*
The 73°F temperature for February was exceptionally warm for that time of
year. It is suspected that ground and crawl space temperatures fluctuate
much more slowly than ambient temperature; therefore, chlordane vaporization
from treated surfaces would not increase enough during peak daytime tempera¬
ture to show appreciable concentration increase.
Although the airborne concentration of chlordane in filtered houses con¬
tinued to increase as the study progressed, chlordane levels measured in the
control houses increased at a considerably greater rate than those in any of
the filtered houses. This reinforces the filter load data and further demon¬
strates that polyurethane filters will remove airborne chlordane. However,
the filters did not remove enough chlordane to maintain levels below S pg/m*.
Samples collected with filters installed showed 76% (45 of 59) were greater
than the NAS guideline.
The direct correlation between chlordane concentration and ambient
temperature suggests that most of the crawl space houses at McConnell should
have airborne chlordane concentrations below 5 pg/m* during part of the year.
Temperatures normally experienced at McConnell AFB are depicted in Table 3.
Sampling data indicated most chlordane concentrations were less than 5 pg/m*
when ambient temperature were less than 60*F. Based upon this and Table 1,
chlordane levels in the crawl space houses should be less than 5 pg/m* from
November through March. It is theorized that the installation of the
polyurethane filter should keep chlordane levels safely below 5 pg/m* from
October through April.
There is a high probability that an annual TWA for most of the McConnell
crawl space houses may be less than 5 pg/m*. However, there is insufficient
sampling data throughout the year to calculate a TWA and sampling variability
precludes making such projections for each house based solely upon temperature
data and one or two samples. Also, the NAS has not specified whether the
5 pg/m* guideline is a TWA or ceiling level. The NAS has stated that the
"5 pg/m* should be regarded as an interim guideline for exposures not exceed¬
ing 3 years." (3) This infers that a 3-year TYA could be applied.
The mechanism for chlordane intrusion into the crawl space housing at
McConnell AFB is not fully understood. It is suspected that the chlordane
contaminated air in the crawl space is penetrating the return air ventilation
11
Table 3
Temperature Data - McConnell AFB*
Month
Maximum Mean
Jan
41
21
Feb
46
26
Mar
54
33
Apr
67
46
May
77
56
Jun
87
66
Jul
91
70
Aug
90
69
Sep
81
60
Oct
72
50
Nov
54
35
Dec
44
26
*Data provided by Base Weather Service, McConnell AFB.
duct which is under negative pressure. The chlordane is then distributed
throughout the unit. Or the chlordane may be penetrating the floor above the
crawl space. Regardless, chlordane concentrations in the houses vary directly
with the ambient outside and crawl_jpace temperatures. This is opposed to
previous DSAF OEHL studies in houses built on concrete slabs where chlordane
concentrations increased in the colder months. During cold weather, the
heated air in the slab house ventilation ducts warmed the adjacent soil caus¬
ing more chlordane to vaporize and infiltrate into poorly sealed ductwork.
Conversely, the ventilation ducts, return and supply, in the crawl space are
suspended immediately below the floor and are not in contact with the treated
soil. Some of the wood sills and supports may also have been treated with the
chlordane emulsion in 1979. Because an air buffer exists between treated
surfaces and the ductwork, it is theorized that the heat transfer be
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