HEALTH CONSULTATION
Evaluation of Indoor Air Sampling 4625 Rockwood Parkway
SPRINGVALLEY CHEMICAL MUNITIONS
(a/k/a AMERICAN UNIVERSITY EXPERIMENT STATIONS/SPRING VALLEY)
WASHINGTON, DISTRICT OF COLUMBIA
BACKGROUND AND STATEMENT OF ISSUES
The U.S. Environmental Protection Agency (EPA) asked the Agency for Toxic Substances and
Disease Registry (ATSDR) to review indoor air and soil gas sampling data to determine if
exposure to chemical substances detected in indoor air posed an immediate or long-term health
hazard to residents occupying a home at 4625 Rockwood Parkway, Spring Valley. EPA asked
ATSDR to recommend actions necessary to protect the health of building occupants. The house
was occupied at the time of sampling, but vacated at the time ATSDR received the data. The
building occupants lived in the house for less than one year. The property remains vacant with
the potential for American University to lease it to another tenant.
The property at 4625 Rockwood Parkway is located in the Spring Valley Formerly Used Defense
Site (FUDS) in an area adjacent to a debris field on lot 18. The area was formerly occupied by
the American University Experiment Station (AUES) between 1917-1920. During World War I,
the AUES was established to investigate testing, production and effects of chemical warfare
agents, antidotes and protective equipment. The AUES is located on the grounds of the present
American University, which owns and leases the property. A former tenant living in the house
found laboratory glassware and other debris on the property and believed that it came from
former AUES activities.
The former occupants experienced a number of symptoms including rashes, headaches, dry skin
and itchy eyes, respiratory problems, fatigue, joint pain, sore throat and depression. The
occupants were concerned that the symptoms they were experiencing were related to exposure to
hazardous materials originating from AUES disposal areas (Hansen, 2003). ATSDR was not able
to obtain information from the former occupant regarding the number of individuals reporting
symptoms and the onset and duration of the reported symptoms since the former occupant has
vacated the property and left the United States.
In June 2003, W.L. Gore and Associates, Inc. performed soil gas and indoor air sampling at the
property. Copies of the sampling data were provided to the EPA Region 3 office in Philadelphia and the Washington, DC Health Department.
Environmental sampling history
During the period June 10-24, 2003, 31 sampling modules were placed in various locations in
the home and in soil on the property (W.L. Gore and Associates, Inc., 2003). The sampling plan
was designed to collect a broad range of volatile and semivolatile chemicals including petroleum
hydrocarbons, chlorinated hydrocarbons, potential explosive degradation products and potential
chemical warfare agent degradation products. The samples were intended to identify chemical
contaminants that a building occupant might be exposed to from breathing indoor air and
identify if further focused indoor air sampling was warranted.
The sampling modules passively collected organic chemical compounds on an adsorbent
sampling medium, which was later analyzed by a gas chromatograph using a modified EPA
Method 8260/8270. Maximum detected concentrations in indoor air are presented in Table 1. For
additional details on sampling and analytical methodologies, refer to the referenced
environmental sampling report (W.L. Gore and Associates, Inc., 2003).
Detected substances in soil gas included low levels of some polyaromatic hydrocarbons and
several common volatile organic chemicals including petroleum hydrocarbons, BTEX (benzene,
toluene, ethylbenzene and xylene), trimethylbenzenes, napthalene and chloroform. The low
concentrations of chemicals detected in the soil gas would not be high enough to significantly
impact indoor air.
When evaluating indoor air quality, ATSDR considers the widespread nature of many commonly
found chemicals in building indoor air. In addition to an identified source of contamination (such
as a underground waste disposal site), many chemicals routinely detected in indoor air originate
from common sources including cleaning chemicals, gasoline, cosmetics, perfumes, paints, air
fresheners, dry cleaning, cigarette smoke, and cooking byproducts.
In 1982, EPA conducted random air sampling in 15 homes without a known subsurface source of
contamination. Sampling detected the following concentrations: benzene (up to 5.6 ppb),
toluene (up to 1010 ppb), ethylbenzene (up to 7.6 ppb), and xylenes (up to 18 ppb) (EPA 1991).
These concentrations are typical of many indoor air samples taken in urban dwellings and are
considered to be in the range of background. Comparing the maximum detected concentrations
at 4625 Rockwood Parkway (benzene, 0.31 ppb; toluene, 0.52 ppb; ethylbenzene, 0.09 ppb; and
xylenes, 0.41 ppb) to the background values reported by EPA, there does not appear to be an
unusual source of indoor air contamination in the house. No chemical warfare agents, explosives
or their environmental degradation products were detected in the home.
Data sources and quality assurance
In preparing this document, ATSDR reviewed and evaluated information provided in the
referenced documents. In its evaluation ATSDR assumes that adequate measures to preserve
data quality were followed with regard to sampling, laboratory analysis and data reporting, and
that the data provided to ATSDR were representative of the chemical concentrations reported in indoor air and soil gas at the time of sampling.
Table 1. Chemical compounds sampled in
indoor air at 4625 Rockwood Parkway.
| Chemical |
Maximum detected concentration (ppb) |
Chemical |
Maximum detected concentration (ppb) |
| Total petroleum hydrocarbons |
81.00 |
Phenanthrene |
0.26 |
| BTEX |
1.30 |
Anthracene |
0.04 |
| Benzene |
0.31 |
Fluoranthene |
0.02 |
| Toluene |
0.52 |
Pyrene |
0.02 |
| Ethylbenzene |
0.09 |
Vinyl chloride |
ND |
| m,p-Xylene |
0.41 |
1,1-DCE |
ND |
| o-Xylene |
0.22 |
Chloroform |
0.18 |
| C11, C13, C15 hydrocarbons |
1.80 |
Carbon tetrachloride |
ND |
| Undecane |
1.60 |
Dimethyldisulfide |
ND |
| Tridecane |
0.18 |
1,1,2-TCA |
ND |
| Pentadecane |
0.48 |
Chlorobenzene |
ND |
| Trimethylbenzenes |
1.10 |
1,1,1,2-Tetrachloroethane |
ND |
| 1,2,4-Trimethylbenzene |
1.00 |
DMMP |
ND |
| 1,3,5-Trimethylbenzene |
0.09 |
1,4-Thioxane |
ND |
| ct1,2-DCE |
ND |
1,1,2,2-Tetrachloroethane |
0.04 |
| t1,2-DCE |
ND |
1,3-DCB |
ND |
| c1,2DCE |
ND |
1,2-DCB |
ND |
| Polyaromatic hydrocarbons |
1.10 |
DIMP |
ND |
| NAPH, 2MN |
0.01 |
1,4-Dithiane |
ND |
| Napthalene |
0.72 |
Nitrobenzene |
ND |
| 2-methyl napthalene |
0.14 |
2-Nitrotoluene |
ND |
| MTBE |
ND |
Thiodiglycol |
ND |
| 1,1-DCA |
ND |
3-Nitrotoluene |
ND |
| 1,1,1-TCA |
ND |
4-Nitrotoluene |
ND |
| 1,2-DCA |
ND |
Benzothiazole |
0.20 |
| Trichloroethylene |
ND |
4Chloroacetophenone |
ND |
| Octane |
0.61 |
pChlorophenylmethylsulfide |
ND |
| Tetrachloroethylene |
0.43 |
2Chloroacetophenone |
ND |
| 1,4-Dichlorobenzene |
0.07 |
1,3-DNB |
ND |
| Acenaphthene |
0.04 |
2,6-DNT |
ND |
| Acenaphthylene |
0.11 |
pChlorophenylmethylsulfoxide |
0.03 |
| Fluorene |
0.10 |
2,4-DNT |
ND |
| 2,4,6-TNT |
ND |
pChlorophenylmethylsulfone |
0.04 |
| 1,3,5-TNB |
ND |
|
|
ND: Not detected
EVALUATION OF PUBLIC HEALTH IMPLICATIONS OF EXPOSURE TO SUBSTANCES DETECTED IN INDOOR AIR
This section details the ATSDR evaluation of the health impact of exposure to substances
detected in indoor air and determination of the degree of public health hazard. From a review
and evaluation of the indoor air sampling data, ATSDR determines that the detected
concentrations of chemical substances appear too low to create a health hazard to adult or child occupants breathing indoor air at 4625 Rockwood Parkway.
How was sampling data evaluated?
ATSDR scientists evaluate site conditions to determine if people could have been, are, or could
be exposed (i.e., exposed in a past scenario, a current scenario, or a future scenario) to site-related contaminants. When evaluating exposure pathways, ATSDR identifies whether exposure
to contaminated media (soil, sediment, water, air, or biota) has occurred, is occurring, or will
occur through ingestion, dermal (skin) contact, or inhalation.
If exposure was, is, or could be possible, ATSDR scientists consider whether contamination is
present at levels that might affect public health. ATSDR scientists select contaminants for
further evaluation by comparing them against health-based comparison values. Comparison
values (CV) are developed by ATSDR from available scientific literature related to exposure and
health effects. CVs reflect an estimated contaminant concentration that is not likely to cause
adverse health effects, assuming a standard daily contact rate (e.g., an amount of water or soil
consumed or an amount of air breathed) and body weight.
The comparison values do not represent thresholds for adverse health effects. The values
establish contaminant concentrations many times lower than levels at which no effects were
observed in experimental animals or human epidemiologic studies. If contaminant
concentrations are above CVs, ATSDR further analyzes exposure variables (for example,
duration and frequency of exposure), and further considers the range of biomedical literature in
evaluating the health impact of exposure.
ATSDR compared the maximum detected concentrations of chemicals in indoor air to health
protective CVs to identify if further site-specific evaluation of exposure was needed (Table 2).
For the substances that exceeded comparison values, the low concentrations in building indoor
air would result in exposure doses orders of magnitude below doses where toxicity was observed
in studies of exposed animals and people. ATSDR believes these substances are not present at
concentrations posing a health hazard to building residents.
In addition to those compounds that exceeded CVs, several detected compounds lacked health
guideline values and in-depth information regarding inhalation toxicity and were included for
further evaluation (Table 2). In most instances, these chemicals were evaluated by: 1) assessing
them as individual substances rather than generic chemical class, 2) comparing them to similar
compounds with health guidance values, or 3) basing toxicity considerations upon chemical
structure or alternate exposure routes. Three chemicals did not fall into any of these categories:
benzothiazole, p-chlorophenylmethylsulfoxide, and p-chlorophenylmethylsulfone. Available
information from the biomedical literature was identified and evaluated for these compounds.
Although comprehensive toxicity information is lacking, trace concentrations in building indoor
air would result in exposure doses orders of magnitude below doses where toxicity was observed
in animal studies. Based upon the scientific literature, ATSDR believes these substances would
not present a health hazard to building residents at the detected concentrations. Benzothiazole is discussed in more detail later in this document.
Table 2. Chemical substances considered
for further evaluation.
|
Chemical |
Maximum detected concentration
(ppb) |
Comparison value (ppb)
|
Comment |
| Benzene |
0.31 |
0.07 |
No public health hazard. Concentration below concern
for increased cancer or non cancer health effects. |
| Napthalene |
0.72 |
0.44 |
No public health hazard. Concentration below concern for
non cancer health effects |
| Tetrachloroethylene |
0.43 |
0.05 |
No public health hazard. Concentration below concern
for increased cancer or non cancer health effects. |
| 1,4-Dichlorobenzene |
0.07 |
0.05 |
No public health hazard. Concentration below concern
for increased cancer or non cancer health effects. |
| Chloroform |
0.18 |
0.02 |
No public health hazard. Concentration below concern
for increased cancer or non cancer health effects. |
| 1,1,2,2-Tetrachloroethane |
0.04 |
0.004 |
No public health hazard. Concentration below concern for
increased cancer or non cancer health effects. |
| Total petroleum hydrocarbons |
81.00 |
NA |
Evaluated as individual compounds, no public health hazard. |
| BTEX |
1.30 |
NA |
Evaluated as individual compounds, no public health hazard. |
| C11, C13, C15 hydrocarbons |
1.80 |
NA |
No public health hazard. Concentration of straight chain
hydrocarbons below level of concern for adverse health effects. |
| Undecane |
1.60 |
NA |
No public health hazard. Concentration of straight chain
hydrocarbons below level of concern for adverse health effects. |
| Tridecane |
0.18 |
NA |
No public health hazard. Concentration of straight chain
hydrocarbons below level of concern for adverse health effects. |
| Pentadecane |
0.48 |
NA |
No public health hazard. Concentration of straight chain
hydrocarbons below level of concern for adverse health effects. |
| Trimethylbenzenes |
1.10 |
NA |
Evaluated as individual compounds, no public health hazard |
| Polyaromatic hydrocarbons |
1.10 |
NA |
Evaluated as individual compounds, no public health hazard |
| 2-Methylnapthalene |
0.01 |
NA |
Evaluated as individual compounds, no public health hazard |
| Octane |
0.61 |
NA |
No public health hazard. Concentration of straight chain
hydrocarbons below level of concern for adverse health effects. |
| Acenaphthylene |
0.11 |
NA |
Toxicity was assumed to be similar to acenapthene. Concentration
below concern for increased cancer or non cancer health effects. |
| Phenanthrene |
0.26 |
NA |
Toxicity was assumed to be similar to anthracene. Concentration
below concern for increased cancer or non cancer health effects. |
| Benzothiazole |
0.20 |
NA |
Concentration below concern for increased cancer or non
cancer health effects. |
| pChlorophenylmethylsulfoxide |
0.03 |
NA |
Concentration below concern for increased cancer or non
cancer health effects. |
| pChlorophenylmethylsulfone |
0.04 |
NA |
Concentration below concern for increased cancer or non
cancer health effects. |
NA: Not available or applicable to inhalation exposure route.
Short-term health effects
Acute health impacts are generally observed following short-term exposure to very high
concentrations. No chemical substances were detected at concentrations high enough to create
an acute or immediate health hazard. Except for petroleum hydrocarbons detected at a
maximum of 81 ppb in the basement along the garage wall, all chemical substances were below
1 part per billion (ppb). Generally, such low concentrations would not be expected to pose an
immediate or short-term threat.
Longer-term health effects
An evaluation of the indoor air sampling data indicates no appreciable cancer or non-cancer
health impacts from breathing substances detected in indoor air. Chemical concentrations were
too low to result in health harm, even from breathing maximum levels on a daily basis for
months to years. The previous tenants occupied the home for a short period (approximately one
year), further limiting the extent and duration of their exposure.
Relationship of indoor air at 4625 Rockwood Parkway to specific health concerns
Benzothiazole and detection of sulfur mustard (mustard gas) breakdown products
Prior to the recent indoor air and soil gas sampling, the U.S. Army Corps of Engineers (USACE)
performed soil sampling at this property in 2002 and documented the sampling in a report by
Parsons Engineering Science. The report indicates surface soil contamination with arsenic,
polyaromatic hydrocarbons and environmental degradation products of sulfur mustard (Parsons,
2002). In 2004, USACE plans to remediate the soil contamination. ATSDR will discuss and
evaluate public health impacts of soil contamination in a separate document currently under
development.
A letter to the EPA Region 3 Administrator by legal counsel retained by a previous resident of
4625 Rockwood Parkway expresses concern that benzothiazole is "a by-product of mustard gas"
(Barer, 2003). ATSDR was unable to find any information in the scientific literature to support
that assertion. Although present in surface soil, sulfur mustard degradation products, including
1,4-thioxane, 1,4-dithiane and thiodiglycol were not detected in indoor air.
Information in the National Libraries of Medicine's Hazardous Substances Databank (HSDB)
reveals that benzothiazole is a volatile organic chemical common to several manufacturing
processes, is listed as a flavor additive in food, an accelerator in the rubber vulcanization
process, as an antimicrobial and antifungal agent commonly found in shoe insoles, and as a
component of cyanine dyes. Benzothiazole has been studied in animal toxicity experiments and
occupational health surveys in the rubber industry, though toxicity information is limited. An
acute inhalation lethality study in rats demonstrated a median lethal dose of 253,199 ppb
(RTECS, 2003). Trace levels reported in indoor air in the Rockwood property (up to 0.2 ppb)
would be unlikely to cause health harm.
ATSDR did locate one article discussing benzothiazole and its use as a chemical intermediate in
producing organosulfur compounds for use as pre-exposure therapies for sulfur-containing
agents such as sulfur mustard (Ternay et al., 2000). A question arose regarding the possibility
that the benzothiazole detected in indoor air might have resulted from wastes generated by past
research or production when the AUES was in operation. Upon further evaluation, it appears that
the benzothiazole compound identified in the Ternay study has a different chemical structure
than the benzothiazole detected in the home and appears unrelated to AUES activity.
Benzothiazole was not detected in soil gas, which would indicate that the source of this
substance was not in the subsurface. Additionally, indoor air sampling did not find it in the
basement, which would have been expected if the source were under the home. The maximum
concentration was detected in the bedroom. Benzothiazole is used as an antifungal agent in shoe
insoles, and a common compound used in producing in rubber products. Given its use in
common household products there may be a local source in the room that resulted in the
detection in indoor air.
The US Army Center for Health Promotion and Preventive Medicine, (USACHPPM) was unable
to locate any information in the scientific literature to suggest that two other detected
compounds, pChlorophenylmethylsulfoxide and pChlorophenylmethylsulfone are chemical
warfare agent breakdown products (Baron, 2003).
Odors in the home
The former occupant expressed concern regarding odors reminiscent of cut hay and its possible
relation to the presence of war gases like phosgene (Barer, 2003). Phosgene has a characteristic
odor that can only be detected briefly at the time of initial exposure. Around 0.5 parts per million
in air (500 parts per billion), the odor has been described as pleasant and similar to that of new-mown hay or cut green corn. At high concentrations in the range of human toxicity, the odor
may be strong, stifling, and unpleasant. Human symptoms at concentrations around 4-10 ppm
(parts per million, equivalent to 4000-10,000 ppb) include eye and throat irritation, tightness in
the chest, shortness of breath, wheezing, and coughing (IPCS, 1997). Phosgene or agent-specific
degradation products were not detected in indoor air.
Presence of mold or mildew might explain some of the odors detected in the home. Exposure to
molds can cause symptoms in sensitive individuals such as nasal stuffiness, eye irritation and
respiratory problems, which were all reported as health symptoms in the residents. Molds are
found in virtually every environment and can be detected year round both indoors and outdoors.
Mold growth is encouraged by warm and humid conditions. Indoors they are commonly found in
basements or showers where humidity levels are high.
Inside homes, mold growth can be slowed by keeping humidity levels below 50% and
ventilating showers and cooking areas. Mold growth can be removed with commercial products
or a weak bleach solution (1 cup of bleach in 1 gallon of water). For more information on molds
and indoor air quality, go to the Centers for Disease Control and Prevention website at
http://www.cdc.gov/nceh/airpollution/default.htm or the USEPA website at
http://www.epa.gov/iaq/molds/moldguide.html .
Carbon monoxide
While the former tenants occupied the home, elevated concentrations of carbon monoxide were
reportedly detected. This was apparently due to a faulty heating system, which was subsequently
corrected by the building owner (Hirsch, 2003). ATSDR has no information on the past levels of
carbon monoxide measured in the home or when the levels were detected. The signs and
symptoms of non-lethal carbon monoxide poisoning, especially from intermittent, low-level
exposures can be mistaken for other illnesses common seen in the primary care setting including
headaches, chronic fatigue, depression, and viral illness (Abelsohn et al., 2002). These
symptoms are similar to health concerns expressed by the former resident.
Child Health Considerations
ATSDR is committed to protecting children's health. ATSDR recognizes that infants and children may be more
sensitive than adults to environmental exposure in communities faced with water, soil, air or food contamination. This
concern for possible increased sensitivity is the result of several factors, including: (1) children are smaller than adults,
resulting in higher doses of chemical exposure per unit body weight; (2) children's bodies may be more sensitive to the
effects of chemical exposures. Children have developing body systems which can sustain permanent damage if toxic
exposures occur during critical growth stages. At 4625 Rockwood Parkway, ATSDR used health guidelines protective
for children in its evaluation of public health impact from exposure to chemical substances in indoor air. At the low levels detected no adverse health impacts in children would be expected.
CONCLUSIONS
From a review and evaluation of the indoor air sampling data and available toxicological and medical information
relevant to the substances of interest, ATSDR concludes that the presence of low levels of volatile and semivolatile
substances in indoor air at 4625 Rockwood Parkway poses no apparent public health hazard to adult or child occupants.
The presence of laboratory glassware and debris from AUES in soil at the property indicates the possibility of a
subsurface disposal area in the vicinity of the residence. The soil gas sampling was conducted during heavy
precipitation, which might have affected the accuracy and validity of the soil gas data. As a result, ATSDR does not
have confidence that the soil gas data is adequate to rule out the presence of a subsurface source. Further sampling of
shallow and deep soil gas would serve to confirm the previous sample results obtained from the passive sampling modules and eliminate the uncertainty about the presence of subsurface contamination.
Past detection of elevated carbon monoxide concentrations in the home indicate that carbon monoxide levels were
elevated and may have contributed to reported health symptoms. Although the furnace system was previously
serviced, it is unknown what current carbon monoxide levels are in the home and if the combustion sources that have
the potential to generate carbon monoxide (i.e. furnace) are operating as designed.
RECOMMENDATIONS
ATSDR makes the following recommendations:
- Conduct further confirmatory sampling at the property. The first phase should focus on deep and shallow
soil gas. Soil gas sampling should be performed using an EPA-approved methodology capable of detecting
chemical warfare agent degradation products.
- If sampling reveals volatile constituents in the soil vapor that could potentially impact indoor air, then
further indoor air sampling should be conducted utilizing an EPA-approved sampling method ideally
designed to sample indoor air over a 24-hour period under a worst-case situation (i.e. windows closed,
mechanical ventilation running, etc.).
- Ensure carbon monoxide levels are within a safe range prior to leasing to future tenants.
- Sample for carbon monoxide with windows closed and the heating system operating under normal conditions.
- Install a UL/CPSC approved CO monitor.
- Service the HVAC system and other combustion sources in the home as necessary to ensure proper operation.
REPORT AUTHORS
Scott Sudweeks
Toxicologist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Technical advisors:
Gary Campbell
Chief, Defense section
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
Laura Frazier
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation
HOW TO CONTACT ATSDR
You may contact Scott Sudweeks at ATSDR in Atlanta, GA by calling the toll-free number (888) 42-ATSDR
(888-422-8737). You may also contact Tom Stukas, ATSDR's Regional Representative in Philadelphia, PA at
(215) 814-3142.
Written correspondence should be directed to:
ATSDR/DHAC/FFAB
1600 Clifton Road, MS E-32
Atlanta, GA 30333
Additional information about ATSDR services and the public health impacts of exposure to hazardous substances is
available on the ATSDR web site at http://www.atsdr.cdc.gov.
REFERENCES
Abelsohn, A; Sanborn, M; Jessiman, B; Weir, E. 2002. Identifying and managing adverse environmental health effects:
6. Carbon monoxide poisoning. CMAJ. 166(13). June 25, 2002.
Barer, GS. 2003. Letter to Donald Welsh, EPA Region 3. July 15, 2003.
Baron, J. 2003. U.S. Army Center for Health Promotion and Preventive Medicine. Written communication commenting
on draft evaluation of indoor air sampling, 4625 Rockwood Parkway. September 2, 2003.
Hansen, F. 2003. Testimony before the DC Council, Committee of Public Works and the Environment and Committee
on Human Services. July 14, 2003.
Hirsch, S. 2003. EPA Region 3, Philadelphia, PA. Personal communication, July 24, 2003.
International Programme on Chemical Safety (IPCS).1997. Environmental Health Criteria 193: Phosgene. United
Nations Environment Program, International Labor Organization and the World Health Organization.
Parsons Engineering Science, Inc. 2002. Report of Analytical Results - American University Experiment Station
(AUES) List of Chemicals for Four Spring Valley Operable Unit 4 Properties. Washington, D.C. Prepared for U.S.
Army Corps of Engineers, Baltimore District. May 8, 2002.
Registry of Toxic Effects of Chemical Substances (RTECS). Benzothiazole. U.S. Department of Health and Human
Services. 2003.
Ternay, A.L; Brzezinska, V; Sorokin C; Cook, C; Lyaschenko Yu. 2000. Organosulfur compounds as pre-exposure
therapy for threat agents. J Appl. Toxicol. 20, S31-34.
W.L. Gore & Associates, Inc. 2003. GORETM survey for site assessment final report, 4625 Rockwood Parkway,
Washington, DC. Addendum. July 18, 2003.
U.S. Environmental Protection Agency (EPA). 1991. Introduction to Indoor Air Quality: A Reference Manual. July,
1991.
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