HEALTH CONSULTATION
(Exposure Investigation-Phase II)
SPRING VALLEY NEIGHBORHOOD
(ALIASES: SPRINGVALLEY MUNITIONS AND AMERICAN UNIVERSITY)
WASHINGTON, DISTRICT OF COLUMBIA
OBJECTIVE
This exposure investigation examined individuals in the Spring Valley neighborhood
of Washington, D.C. The investigation focused on whether these individuals had
been exposed to arsenic contamination in their yards. The investigation was
conducted from July through November 2002 and is the follow-up to an earlier
(March 2002) investigation. Urine arsenic levels were tested in 40 individuals:
34 adults and six children aged 21 months to 15 years. All of these individuals
were residents of 19 homes where the yards showed elevated soil arsenic levels,
or homes adjacent to properties under remediation for elevated soil arsenic
levels.
SUMMARY AND STATEMENT OF ISSUES
Background
During World War I, at a site known as the American University Experimental
Station in northwest Washington, D.C, the U.S. Army conducted chemical warfare
research. During research and training operations, chemical weapons were detonated
at several locations. Lewisite (which contains arsenic) and mustard gas were
among the chemical warfare agents reportedly tested. Chemical agents—including
hazardous substances, ordnance, and explosive waste—were buried in the
area. Long after the Army vacated the former Experimental Station site, the
entire area underwent extensive development. Today it is home to the American
University campus and to residential homes that comprise the Spring Valley neighborhood
[1].
In January 1993, a contractor digging a utility trench in Spring Valley uncovered
buried ordnance. Once notified, the U.S. Army Corps of Engineers (Corps) launched
Operation Safe Removal, extracting some 141 ordnance items including suspected
chemical munitions containing mustard gas and fuming sulfuric acid. To identify
other potentially impacted areas, the Corps reviewed historical records and
conducted extensive geophysical surveys with electromagnetic instruments. In
addition, to characterize the extent and nature of chemical contamination, the
Corps collected soil samples in potentially affected areas. Discovery and remedial
efforts continue in Spring Valley and related areas [2].
ATSDR Activities at Spring Valley
The Agency for Toxic Substances and Disease Registry (ATSDR) has been working
with the following agencies and groups:
- The Department of the Army,
- the Army Corps of Engineers,
- the U.S. Environmental Protection Agency (EPA),
- the District of Columbia Department of Health (DC DOH),
- American University,
- the Spring Valley Science Advisory Panel,
- the Spring Valley Restoration Advisory Board, and
- area residents
to assess the public health impact of environmental contamination from hazardous
substances. At the request of the DC DOH, the EPA, or the Corps, between June
1997 and the present ATSDR has prepared five health consultations and one technical
assistance document assessing soil contamination at the site.
In December 2000, contaminated soil was identified at the Child Developmental
Center at American University. Surface soil samples collected from the playground
were contaminated with arsenic at an average concentration of 57 micrograms
per gram of soil (µg/g) and a maximum concentration of 498 µg/g.
During February 1-2, 2001, ATSDR conducted an exposure investigation at the
Child Developmental Center. Hair samples were analyzed for arsenic several weeks
after exposure had stopped. Hair samples from 28 children and four adults did
not indicate elevated arsenic exposure in children or workers at this center.
The property was subsequently remediated [3, 4].
In March 2002, a second exposure investigation examined individuals in the Spring
Valley neighborhood for possible exposure to arsenic contamination in their
yards. A total of 32 individuals were tested: 23 adults and nine children aged
16 months to 13 years. These individuals lived in 13 homes at which elevated
composite soil arsenic levels were found in the yards. These individuals' urine
and hair were tested and in each of their homes household dust was analyzed
for arsenic. Urine and hair arsenic testing showed low levels of arsenic exposure
not expected to cause health problems in this population [5].
Other Site-Related Activities
On February 10 and 15, 2001, Washington Occupational Health Associates, Inc.
(WOHA), collected hair and urine samples from students and staff at American
University. The target population for this exposure investigation included students
and staff who attended the Center in the past 12 months, maintenance and grounds
crew members, and athletes who use the intramural fields. Sixty-six persons
(39 adults and 27 children) provided hair samples. Four adults provided urine
samples. WOHA concluded that their exposure investigation indicated no elevated
levels of arsenic in the population tested [6].
The Corps has continued to characterize soil contamination in residential properties
in potentially affected Spring Valley areas. This testing documented arsenic
levels in composite soil samples collected from residential areas. The samples
ranged from background levels to a maximum of 202 parts per million (ppm). Residents
of Spring Valley have expressed concern over possible health effects from exposure
to this contamination. In response to these concerns, the DC DOH asked ATSDR
to evaluate potential exposure to arsenic in residents of contaminated properties.
Rationale for an Exposure Investigation
The Spring Valley Science Advisory Panel recommended the second phase of this
exposure investigation. The Panel was concerned that the first phase of the
exposure investigation was conducted in early spring—a time of little outdoor
activity and, consequently, little potential for soil contact. By performing
the investigation at a time of presumed maximal exposure activities, ATSDR was
able to exclude hair analysis (which is not considered a reliable indicator
of arsenic exposure) and focus on arsenic levels in urine.
Within a few days following exposure, ingested arsenic is rapidly excreted
from the body into the urine. Accordingly, ATSDR analyzed urine samples for
arsenic as an indicator of exposure within the preceding few days [7]. The urine
samples were analyzed for either total arsenic or speciated arsenic (inorganic
arsenic, dimethyl arsenic acid, and methylarsonic acid). In this health consultation
the term "inorganic arsenic" is used interchangeably with "speciated
arsenic" and refers collectively to all inorganic forms of arsenic, including
dimethyl arsenic acid and methylarsonic acid. By conducting speciated analysis,
exposure to inorganic arsenic was differentiated from exposure to less toxic
forms of arsenic found in food, such as fish and shellfish [8].
Methods
Target Populations
To assess exposure to arsenic, ATSDR tested urine in Spring Valley residents
who were classified into one of three groups: (1) individuals who participated
in the first exposure investigation, (2) individuals who were living on, or
adjacent to, property under remediatation, and (3) individuals who had a single,
elevated level of arsenic in their yard.
Consent/Confidentiality
Prior to testing, each participant—and a parent or legal guardian of each
minor participant—was required to sign an informed consent/assent form.
Sample copies of these forms are in Attachment A. In addition
to completing a consent form, each family was asked a few questions about their
exposure history.
Individual test results and an explanation of their meaning were provided to
the participants in writing. An ATSDR physician was available to discuss individual
results by phone and, during a community visit at the local hospital, in person.
Recommendations for follow-up actions were made, if indicated. Individual test
results were not made available to the public; confidentiality was protected
according to federal and state laws.
Test Procedures
DC DOH staff distributed urine specimen cups and instructions to all participants
in the exposure investigation. Participants were advised not to eat fish or
shellfish for 3 days before donating a first-morning void urine sample. In an
attempt to collect urine at the time of the highest likelihood of exposure—that
is, during peak outside activities or during soil remediation—urine collection
was spread over the late summer and fall.
The urine samples were sent to National Medical Services laboratories in Willow
Grove, Pennsylvania. The samples were analyzed for total and speciated arsenic
by graphite furnace atomic absorption spectroscopy and by atomic fluorescence
spectroscopy. Urine creatinine was also analyzed. Test results were reported
as micrograms of arsenic per liter of urine (µg/L) and as micrograms of
arsenic per gram of creatinine (µg/g creatinine) [9].
Results
A "Brief Arsenic Exposure Questionnaire" (Attachment B) was administered
at the time of urine sampling. This questionnaire revealed eight families who
owned pets that spend time outdoors; thus the pets might be a source of soil
being tracked into the house. Six individuals reported having recent contact
with soil in their yard and one individual reported being a smoker. Three persons
reported eating seafood within a short time of providing the sample.
All individuals tested had total urinary arsenic levels between non-detect
and 76 µg/L. The detection
limit was 1.0 µg/L. Most (93%, 37/40) of the participants in this exposure
investigation had inorganic urinary arsenic levels of less than 10 µg/L—interpreted
by the National Medical Services as "non-detect" and by ATSDR as "not elevated."
A few (7%, 3/40) of the individuals had reportable levels of inorganic arsenic
in their urine: 10µg/L, 14 µg/L, and 29 µg/L. When adjusted for dilution using
creatinine correction methods, these three individuals' inorganic arsenic levels
were 7 µg/g creatinine, 24.5 µg/g creatinine, and 13.4 µg/g creatinine, respectively.
Attachment C contains a table of individual results grouped
by household.
During this investigation some inconsistencies appeared in the laboratory's
procedures for analyzing urine arsenic. As stated in the exposure investigation
protocol (Attachment D), ATSDR requested total and speciated arsenic analysis
for all urine specimens. National Medical Services' policy, however, was only
to speciate samples with a total arsenic level above 20 µg/L. Because
the discrepancy between the policy and ATSDR's request was discovered midway
through the investigation, some samples were only tested for total arsenic.
National Medical Services also erred in only reporting speciated results for
some samples rather than reporting both total and speciated results. However,
none of these procedural inconsistencies compromised the overall assessment
of arsenic exposure in this population. All elevated total arsenic samples were
speciated and no speciated results were high enough to indicate the potential
for adverse health effects.
DISCUSSION
To evaluate exposure, arsenic is measured in urine, hair, or blood. Measurement
of arsenic in blood is not a reliable indicator of chronic exposure to low levels
of arsenic—it is cleared from the blood within a few hours and reflects
only very recent exposure. Blood arsenic levels also are difficult to interpret
because the relationship between levels of exposure and blood concentrations
has not been well established [10].
Urine arsenic is the most reliable method for measuring arsenic exposure, particularly
exposures occurring within a few days of the specimen collection. Fluctuations
in urine excretion rates make a 24-hour collection an optimal sample. Ease of
collection, however, has resulted in most exposure studies using a first-morning
void or a random sample. In fact, the first-morning void urine results have
correlated well with 24-hour results [7]. Speciated urinary arsenic is preferable
to total urinary arsenic because the speciated forms can distinguish between
exposure to inorganic arsenic and its metabolites and the relatively nontoxic
forms of organic arsenic commonly found in seafood [7, 8].
Individuals in this exposure investigation had their urine tested for total
arsenic (which could come from all sources—food, water, air, soil, and
dust), for inorganic arsenic (which might be coming from contaminated soil and
dust), or for both. The total urinary arsenic is mostly organic arsenic from
food sources, which is much less toxic than inorganic arsenic. If the total
urinary arsenic was not elevated, inorganic arsenic testing was not always performed.
This exposure investigation (EI) included individuals who (1) participated in
the first phase of the exposure investigation, (2) who were living on, or adjacent
to, property that was being remediated, or (3) who had a single elevated level
of arsenic in their yard. Nine of the 13 households from the first EI chose
to participate in this second EI. Three of these families were having their
yards remediated when the urine testing was done. An additional six households
fell into the second group of those who had their urine tested while an adjacent
property was under remediation. Four more households were added to this EI because
they had one elevated arsenic level in their yard.
The American Conference of Industrial Hygienists maintains guidance values
for assessing the level of contaminants in workers who are potentially exposed
in occupational settings. For the monitoring of worker's urinary inorganic arsenic
levels, concentrations up to 35 µg/L are considered acceptable. Although
none of the Spring Valley residents were likely exposed to inorganic arsenic
through an occupational environment, this level is relevant because it is below
the point at which adverse health effects are expected in a worker population.
None of the 40 exposure investigation participants had inorganic arsenic levels
above 35 µg/L.
In summary, the urine arsenic levels in this exposure investigation show low
levels of exposure, consistent with what might be found in the general population.
These levels would not be expected to cause any health problems. Only three
of the individuals tested had reportable inorganic arsenic levels (10 µg/L
or higher). All three of the individuals with inorganic arsenic in their urine
were adults. Two of the elevated inorganic arsenic levels were from the same
household. When adjusting the results using creatinine correction methods, one
of the individuals with a slightly elevated result (10 µg/L) had an adjusted
inorganic arsenic level (7 µg/g creatinine) below the reportable limit.
All individuals tested had total urinary arsenic between non-detect and 76
µg/L. The detection level was 1.0 µg/L. It is not clear whether the detectable
levels of inorganic arsenic in the three individuals are related to soil arsenic
contamination. While dietary arsenic is comprised mostly of organic arsenic,
it does contain a small percentage of inorganic arsenic [7]. Dietary arsenic
from a seafood meal can contribute 10–15% inorganic arsenic to the total
arsenic content [8]. The individual with the inorganic arsenic level of 14 µg/L
had consumed seafood in the 3 days before testing.
CONCLUSIONS
- Overall, urine arsenic testing showed no significant arsenic exposure in
the population.
- Three individuals had slight elevations in their urine inorganic arsenic
levels.
- These levels are not expected to cause health problems.
RECOMMENDATIONS
- Individuals with mild elevations of inorganic arsenic should have follow-up
urinalysis for arsenic.
- All of the tested individuals should discuss their results with their personal
health care provider.
- Individuals, or their health care providers, can discuss their results with
an ATSDR physician if they choose to do so.
AUTHORS, TECHNICAL ADVISORS
Prepared by
Robert H. Johnson, MD
Medical Officer
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Steve Dearwent
Epidemiologist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Loretta Bush
Health Communication Specialist
Community Involvement Branch
Division of Health Assessment and Consultation
Reviewed by:
John E. Abraham, PhD, MPH
Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Susan Metcalf, MD
Section Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
REFERENCES
- US Environmental Protection Agency. Spring Valley Munitions Site analytical
summary. Washington, DC: US Environmental Protection Agency; 1994.
- Agency for Toxic Substances and Disease Registry. Public Health Consultation
for assessment of soil sampling results at the American University, Washington,
DC. Atlanta: US Department of Health and Human Services; 1997 Aug 26.
- Agency for Toxic Substances and Disease Registry. Report assessing public
health implications of arsenic in soils at the American University Child Development
Center. Atlanta: US Department of Health and Human Services; 2001 Mar 28.
- Agency for Toxic Substances and Disease Registry. Health consultation/exposure
investigation for Spring Valley Chemical Munitions (a.k.a. American University
Child Development Center), Washington, DC. Atlanta: US Department of Health
and Human Services; 2001 Mar 8.
- Agency for Toxic Substances and Disease Registry. Exposure investigation
for Spring Valley Neighborhood (a.k.a. Spring Valley Chemical Munitions/American
University) Washington, D.C. Atlanta: US Department of Health and Human Services;
2002 Jun 28.
- Washington Occupational Health Associates Inc. Arsenic exposure investigation
at American University, Washington, D.C. Washington, DC; 2001 Mar 26.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for
arsenic (update). Atlanta: US Department of Health and Human Services; 2000
Sep.
- Kalman, DA et al. The effect of variable environmental arsenic contamination
on urinary concentrations of arsenic species. Environ Health Perspect 1990;89:145-51.
- National Medical Services. Product services manual. Willow Grove, PA: National
Medical Services; 2001.
- National Research Council. Arsenic in drinking water. Washington, DC: National
Academy Press; 1999.
- Norin H et al. Concentration of inorganic and total arsenic in fish from
industrially polluted water. Chemosphere 1985;14:325-34.
ATTACHMENT A: CONSENT FORM FOR PARTICIPATION
Consent Form for Participation
Spring Valley Exposure Investigation
(Participant Consent for Specimen Testing)
An exposure investigation is being conducted to determine if you were exposed
to arsenic.
The Washington, D.C., Department of Health and the Agency for Toxic Substances
and Disease Registry (ATSDR) is offering free voluntary urine testing for arsenic
exposure for residents with elevated levels of arsenic in the soil of your yard.
Along with the free testing, exposure information will be collected by means
of a brief questionnaire. Participation in this investigation will enable you
to know your own levels of arsenic and will enable the local agencies to identify
if public health actions are needed to reduce exposure.
Benefits
I understand that I will benefit from participating by learning whether I (or
my child/ward) have had elevated exposures to arsenic. If elevated exposure
has occurred, I will receive information on how to reduce current and future
exposure. Written information about arsenic exposure will be available to me
and to my physician, if I identify him or her in the questionnaire.
Procedure/Tests:
A representative of the Washington, D.C., Department of Health will distribute
urine specimen cups and instructions to all participants during the week before
the exposure investigation. The participants will collect the first urine they
make in the morning. This urine specimen will be picked up by a Department of
Health staff member.
Participation
I understand that my participation is voluntary. Furnishing any information
is voluntary and even if I agree to participate and sign this form, I can stop
my participation or my child's/ward's participation at any time without penalty
or loss of benefits. I understand and agree that there is no provision for compensation
or medical treatment offered by ATSDR on the basis of the test results or in
the event of injury from participation. I understand that I must sign this form
to participate.
Results
I understand every effort will be made to provide the results of my tests in
writing to me within approximately 2 months. However, unforeseen circumstances
might delay the date. Results that are of immediate health concern will be reported
to me as soon as they are known. If my results reveal an elevated value of arsenic,
I understand that I should notify my personal physician.
Confidentiality
Confidentiality will be protected to the fullest extent possible according to
state and federal laws. Any reports produced from this information will give
only group information and not identify specific individuals. I understand that
if I participate in a confidential manner, any forms containing my name or address
will be kept in locked cabinets at ATSDR and the Washington, D.C., Department
of Health. Test results may be released only to other federal, state, and local
public health (and environmental) agencies, if permitted by me. I understand
if I want my results sent to my physician, I must provide the contact information
and my signature authorizing a release of this information.
Contact
If I have any additional questions about this investigation or the testing,
I may contact Dr. Robert Johnson of ATSDR at 1 (888) 422-8737.
Consent
The risks and benefits of this exposure investigation have been explained to
me. All of my questions have been satisfactorily answered. I hereby freely and
voluntarily give my signed consent for participating in the testing described
above.
I, (print)_____________________________, the undersigned, agree to urine sampling
and completing questionnaires for:
(___) Myself
I, (print)_____________________________, the undersigned, agree to urine and
hair sampling and completing questionnaires for:
(___) Myself
(___) My child/ward, ______________________, age -___
(___) My child/ward, ______________________, age -___
(___) My child/ward, ______________________, age -___
(___) My child/ward, ______________________, age -___
Signature: ____________________________________________ Date: ________________
Signature: ____________________________________________ Date: ________________
Address: ________________________________________________________________________________________
Phone #: _____________________
Witness:
(print name) _____________________
(signature) _____________________
Assent Form for Children
(7- 17 years of age)
A statement to be read to children in the presence of the parent/guardian:
"We want to find out if you have been exposed to arsenic. Arsenic is something
that you cannot see but might cause illness. To know if you have arsenic in
your body, we would like to take a sample of your urine. Providing a sample
is considered very safe, and your mother/father/guardian has said that it would
be all right for you to do this."
"Do you have any questions? May we take a sample of your urine?"
The above information has been read to me and I want to participate.
Name of Child: _______________ Signature of Child:____________________Age____
Name of Child: _______________ Signature of Child:____________________Age____
Name of Child: _______________ Signature of Child:____________________Age____
Name of Child: _______________ Signature of Child:____________________Age ___
Name of Child: _______________ Signature of Child:____________________Age____
Date: ______________
Witness:
(print name) _____________________
(signature) _____________________
ATTACHMENT B: BRIEF ARSENIC EXPOSURE QUESTIONAIRE
Name:____________________________________
| Have you eaten seafood in the past 3 days? |
Y |
N |
| Do you smoke? |
Y |
N |
| Do you have contact with the soil in your yard (gardening, yard work,
etc)? |
Y |
N |
| Have you recently used any pesticides or garden sprays? |
Y |
N |
| Have you eaten any vegetables grown in your garden? |
Y |
N |
| Have you worked with chemically-treated (for example, CCA) wood? |
Y |
N |
| Do you have pets which spend time outdoors? |
Y |
N |
What is your current occupation?__________________________________
ATTACHMENT C: INDIVIDUAL URINE ARSENIC RESULTS BY HOUSEHOLD
Household 1: composite soil arsenic = 88.8 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d |
-- |
| 2 |
n.d |
-- |
Household 2: composite soil arsenic = 81.2 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
-- |
3.4 |
| 2 |
-- |
4.5 |
| 3 |
-- |
20 |
| 4 |
-- |
n.d. |
Household 3: composite soil arsenic = 105 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
29 |
58 |
| 2 |
-- |
13 |
Household 4: composite soil arsenic = 202 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
10 |
-- |
| 3 |
14 |
-- |
| 4 |
n.d. |
-- |
Household 5: composite soil arsenic = 69.5 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
n.d. |
-- |
Household 6: composite soil arsenic = 172 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
n.d. |
-- |
| 3 |
n.d. |
-- |
Household 7: composite soil arsenic = 74.5 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
n.d. |
-- |
Household 8: composite soil arsenic = 93.6 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
n.d. |
-- |
Household 9: composite soil arsenic = 68.2 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
17 |
| 2 |
n.d. |
41 |
Household 10: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
Household 11: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
-- |
20 |
Household 12: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
27 |
| 2 |
-- |
4.9 |
| 3 |
-- |
7.5 |
Household 13: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
n.d. |
-- |
Household 14: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
| 2 |
n.d. |
-- |
Household 15: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
22 |
| 2 |
n.d. |
20 |
Household 16: highest soil arsenic = 406 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
70 |
| 2 |
n.d. |
76 |
Household 17: highest soil arsenic = 7.5 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
25 |
| 2 |
n.d. |
25 |
Household 18: highest soil arsenic = 14.5 ppm
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
-- |
Household 19: no soil data available
| Resident |
Inorganic urine arsenic (µg/L) |
Total urine arsenic (µg/L) |
| 1 |
n.d. |
9.4 |
Note:
(n.d. = non-detect, also interpreted as non-reportable or < 10 µg/L)
(-- = test not performed)
ATTACHMENT D: EXPOSURE INVESTIGATION PROTOCOL: SPRING VALLEY NEIGHBORHOOD–PHASE II
Washington, D.C.
July 20, 2002
Summary
During World War I, the U.S. Army conducted chemical warfare research at the
site of the present Spring Valley neighborhood in Washington, D.C. Chemical
weapons were detonated in several areas during research and training operations.
Chemical agents and weapons were also buried in the same area. The area has
since been developed, and it is now occupied by residential homes and the American
University.
In December 2000, contaminated soil was identified at the Child Developmental
Center (CDC) at the American University. Surface soil samples collected from
the playground were contaminated with arsenic at an average concentration of
57 µg/g and a maximum concentration of 498 µg/g (ATSDR March 28,
2001). ATSDR conducted an exposure investigation (hair analyses for arsenic)
at CDC on February 1-2, 2001. Hair samples from 28 children and four adults
did not indicate elevated arsenic exposure in children or workers at this center,
and the property has subsequently been remediated (ATSDR March 8, 2001).
On February 10 and 15, 2001, Washington Occupational Health Associates, Inc.
(WOHA), collected hair and urine samples at American University. The target
population for this exposure investigation included staff and students who attended
the center in the past 12 months, maintenance and grounds crew members, and
athletes who play on the intramural fields. Sixty-six people (39 adults and
27 children) provided hair samples. Four adults provided urine samples. WOHA
concluded that results of its exposure investigation indicated no elevated levels
of arsenic in the population tested (WOHA March 26, 2001).
Ongoing testing of residential soils in the Spring Valley neighborhood have
shown composite soil levels ranging from background to over 200 µg/g (ppm).
Residents of Spring Valley have expressed concern over possible exposures to
arsenic they might have received during activities at their homes. In March
2002, ATSDR, in conjunction with the Washington, D.C., Department of Health,
collected urine and hair samples from local residents and tested the samples
for arsenic.
Rationale
In order to assess exposure to arsenic, ATSDR will conduct biological monitoring
of potentially exposed residents. Arsenic that is ingested is rapidly excreted
from the body into the urine within a few days after exposure. Therefore, ATSDR
will analyze urine samples for arsenic as an indicator of exposure to arsenic
within the past few days. The urine samples will be analyzed for total arsenic
and speciated arsenic (inorganic arsenic, dimethyl arsenic acid, and methylarsonic
acid). By conducting these two separate analyses, ATSDR will be able to differentiate
exposure to inorganic arsenic from exposure to less toxic forms of arsenic that
occur naturally in fish and shellfish.
Target Population
In order to assess exposure to arsenic, ATSDR will conduct urine testing in
individuals living in Spring Valley who fall into one of three groups: (1) individuals
who participated in the first exposure investigation, (2) individuals who were
living on, or adjacent to, property that is being remediated, and (3) individuals
who had a single elevated level of arsenic in their yards.
Consent/Assent Form
Before testing, each resident and a parent or legal guardian of each minor
participant will be required to sign an informed consent/assent form. A copy
of these forms is in Appendix A.
Test Procedures
Arsenic can be measured in urine, hair, or blood to evaluate exposure. Measurement
of arsenic in blood is not a reliable indicator of chronic exposure to low levels
of arsenic because it is cleared from the blood within a few hours and reflects
only very recent exposure. Blood arsenic levels also are difficult to interpret
because the relationship between levels of exposure and blood concentrations
has not been well-established.
Urine arsenic is the most reliable method for measuring arsenic exposure, particularly
exposures occurring within a few days of the specimen collection. Although a
24-hour urine collection is considered an optimal sample due to fluctuations
in excretion rates, most exposure studies have used a first-morning void or
random sample due to ease of collection. Under steady state exposure conditions,
as would be assumed for most residents of this community, random or spot urine
results have correlated well with 24-hour results. Speciated urinary arsenic
is preferable to total urinary arsenic since the speciated forms can distinguish
between exposure to inorganic arsenic and its metabolites and the relatively
nontoxic forms of organic arsenic commonly found in seafood.
Urine Testing
ATSDR staff will distribute urine specimen cups and instructions for sample
collection to all participants in the exposure investigation. The participants
will be advised not to eat fish or shellfish for 3 days prior to donating a
first-morning void urine sample.
The urine samples will be sent by overnight mail to National Medical Services
laboratories in Spring Willow, Pennsylvania. The sample will be analyzed for
total and speciated arsenic by graphite furnace atomic absorption spectroscopy
and atomic fluorescence spectroscopy. Urine creatinine will also be analyzed.
Test results will be reported as micrograms of arsenic per liter of urine (µg/L)
and in micrograms of arsenic per gram of creatinine (µg/g creatinine).
Inorganic urinary arsenic in unexposed individuals is normally < 20 µg/L.
Total arsenic levels below 100 µg/g creatinine are expected for individuals
without occupational or dietary exposures. (Kalman 1990)
Survey Forms
In addition to completing a consent form, each family will be asked to complete
a short questionnaire that solicits information on the family members' exposure
history.
Reporting Results
Individual test results and an explanation of their significance will be provided
to the participants in writing. An ATSDR physician will be available to discuss
individual results by phone. Recommendations for follow-up actions will be made,
if warranted, including repeat testing or consultation with an occupational/environmental physician.
Individual test results will not be made available to the public, and confidentiality
will be protected according to federal and state laws. At the conclusion of
the investigation, ATSDR will prepare a report which will summarize the findings
of the investigation, but will not reveal personal identifiers.
References
- Agency for Toxic Substances and Disease Registry. Toxicological profile
for arsenic (update). Atlanta: US Department of Health and Human Services; 2000
Sept.
- Agency for Toxic Substances and Disease Registry. Exposure investigation,
Spring Valley Chemical Munitions (a/k/a American University Child Development
Center), Washington, DC, health consultation. Atlanta: US Department of Health
and Human Services; 2001 Mar 8.
- Agency for Toxic Substances and Disease Registry. Report assessing public
health implications of arsenic in soils at the American University Child Development
Center. Atlanta: US Department of Health and Human Services; 2001 Mar 28.
- Kalman DA et al. The effect of variable environmental arsenic contamination
on urinary concentrations of arsenic species. Environ Health Perspect 1990;89:145-51.
- National Research Council. Arsenic in drinking water. Washington, DC: National
Academy Press; 1999
- Washington Occupational Health Associates Inc. Arsenic exposure investigation
at American University, Washington, D.C., health consultation. Washington, DC:
Washington Occupational Health Associates Inc.; 2001 Mar 26.
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