PUBLIC HEALTH CONSULTATION
Assessment of Soil Sampling Results at the American University, Washington, DC
August 26, 1997
From 1917 to 1945, the US Military conducted chemical warfare research at the American University and vicinity. Chemical weapons were detonated in several areas during research and training. Chemical agents and weapons were also reportedly buried in the area. Since that time, the affected area has been developed, and is now residential.
In 1992, construction workers reported odors and eye and skin irritation while excavating at the residence of the university president. Items which were unearthed include laboratory jars and equipment, and an empty 55-gallon drum. White granular layers were observed in one excavation. After analysis, the white granules were determined to be Silvex, a banned herbicide. No other substances were detected which might explain the odor and eye irritation which the workers experienced.
In 1993, workers unearthed unexploded ordnance in a residential area. The US Army responded by removing 141 intact munitions, 43 of which proved to contain chemical warfare agents. Afterward, soil samples were analyzed for suspected chemical agents. As a result, potentially contaminated soils were removed in 1994. Also in 1994, additional evidence of weapons debris was found at the university soccer field.
In 1996, landscapers at the residence of the university president were overcome by odors and irritation to the eyes and respiratory system while excavating. They unearthed several bottles containing unknown materials. Gross measurements of volatile organic compounds (VOCs) in the air were made on the same day. Only one area contained VOCs. A soil sample from this area was contaminated with several VOCs, semi-VOCs, and arsenic, but not at levels which might explain the acute effects which the workers were experiencing. A subsequent sample of soil removed from the excavation revealed a high level of releasable sulfides, which may account for the odors and irritation. Chemical warfare agents and their degradation products were not included in the soil analyses.
Remediation activities were undertaken at the president’s residence. Soils from the landscaping excavation were removed, and the extent of any remaining soil contamination was estimated from gross measurements of VOCs in soil probes. Analysis of the soils indicated some minor contamination with VOCs and arsenic. Again, chemical warfare agents and their degradation products were not included in the soil analyses.
In 1996, US Army contractors completed a Remedial Investigation of soils associated with structures and drain pipes in two areas where chemical agents were stored or used, the Spaulding and Captain Rankin areas. Samples were taken of soils near or underneath the existing structures. Three chemical warfare agents and potential degradation products were included in these analyses. Very few substances were found to exceed both health-based concentration standards and the site background concentrations. A subsequent risk assessment concluded that there was no increased risk of adverse health effects, and no need for further action.
Additional areas were sampled in 1993/4. These samples were split, and analyses were performed by contractors to the US Environmental Protection Agency (EPA). These areas included residential areas, possible warfare test areas, and sports fields. Chemical warfare agents and their degradation products were included in the analyses performed by the Army; none were detected.
The District of Columbia Public Health Commissioner requested ATSDR to review the EPA environmental data, to determine whether there is an increased risk of adverse health effects at the American University and vicinity.
EPA ENVIRONMENTAL DATA
Several areas were sampled by the Army from December, 1993 through March, 1994. These areas are suspected to have been used as shell pits, storage areas, and testing fields and trenches. These samples were analyzed by the Army for the following chemical warfare agents and degradation products: mustard gas, oxathiane, dithiane, lewisite, and thiodiglycol. In addition, the samples were analyzed for explosives and metals. No chemical agents, degradation products, or explosives were detected. The same (split) samples were analyzed by the EPA for metals, volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, and metals. With the exception of one sample, the only substances which exceeded ATSDR comparison values are antimony, arsenic and manganese. One sample at Baker Valley also contained high concentrations of polycyclic aromatic hydrocarbons (PAHs). The following table lists those locations with substance concentrations above the ATSDR comparison values. In addition, those locations with concentrations which are higher than the background concentrations for the vicinity are shaded.
Table 1: Substances present at concentrations exceeding ATSDR Comparison Values. Shaded rows indicate locations at which the substance concentrations also exceed background concentrations. All information except where noted is taken from the Spring Valley Munitions Site Analytical Summary.
|Mustard Testing Field - POI 7||18.8 (7.9-44.4)||
ND (ND-2), MD
1.0 (ND-2), VA1
|POI 24||16.9 (6.3-28.6)|
|American University||22.4 (8.7-40.4)|
|Baker Valley||6.9 (ND-28.9)|
|Mustard Testing Field - POI 7||5.2 (2.1-8.6)||
3.8 (1.1-7.1), MD
5.1 (0.7-18.4), VA1
|Static Test Fire Area - POI 10,11||1.5 (ND-3.7)|
|Mustard Testing Field - POI 16||2.3 (ND-2.3)|
|Old Mustard Field - POI 19||4.1 (1.9-16.0)|
|Woodway Lane residence, POI 20||2.6 (1.4-5.6)|
|Woodway Lane residence, POI 21, 22, 23||1.0 (ND-2.5)|
|POI 1||3.1 (ND-12.8)|
|POI 24||28.5 (7.5-103)|
|Bradley Field/ Major Tolman's Field||9.4 (2.7-43.7)|
|American University||6.9 (2.1-10.6)|
|Baker Valley||5.5 (2.8-8.4)|
|Glenbrook Rd residence||38.7 (1.1-241)|
|Manganese||Mustard Testing Field - POI 7||797 (318-2040)||
640 (ND-7000) Eastern US1
|Static Test Fire Area - POI 10,11||945 (233-2580)|
|Mustard Testing Field - POI 16||492 (250-937)|
|Old Mustard Field - POI 19||540 (309-1450)|
|Woodway Lane residence, POI 20||477(71-1550)|
|Woodway Lane residence, POI 21, 22, 23||487 (303-705)|
|POI 1||511 (289-1100)|
|POI 24||362 (169-692)|
|Bradley Field/ Major Tolman's Field||462 (136-686)|
|American University||656 (23.9-1760)|
|Baker Valley||605 (128-1380)|
|Glenbrook Rd residence||515 (209-973)|
1. From Dragun and Chiasson, “Elements in North American Soils.”
2. This comparison value is based upon the EPA oral reference dose for non-cancer adverse health effects.
3. This comparison value is based upon the EPA oral cancer slope factor.
AntimonyAntimony was detected above the ATSDR comparison value of 20 mg/kg and above the background concentrations at four locations. The four locations include residences, a baseball field, and the American University campus. The maximum concentration of antimony detected at these four areas is 40.4 mg/kg, or twice the comparison value. No adverse health effects are expected to occur as a result of exposure to antimony at these concentrations.
Although the comparison value for arsenic was exceeded at every location sampled, only three locations had levels of arsenic which were elevated above the background concentration. These areas include residences and a baseball field. The highest concentration observed was 241 mg/kg at a residence. Although a lifetime exposure to soil with this maximum concentration of arsenic may cause a slight increase in the risk of skin cancer, this is unlikely, because of the infrequent distribution of the samples with elevated levels of arsenic.
The comparison value for manganese was exceeded at every location. However, these levels, at all locations but one, are most likely due to the natural background concentrations. The remaining location, the Static Test Fire Area, is in a residential area bordering the Dalecarlia Parkway. The most elevated levels are near the parkway. One possible explanation for these levels could be the use of manganese as an additive to unleaded gasoline prior to 1978. The maximum concentration of manganese which was observed was 2,580 mg/kg. Although manganese is an essential dietary mineral, too much manganese can cause adverse health effects. These effects are unlikely to occur at the soil concentrations which were observed at the Static Test Fire Area.
Polycyclic aromatic hydrocarbons, or PAHs, were elevated in only one sample. This sample was in the Baker Valley, near a baseball field. The total amount of PAHs in this samples was 33 mg/kg. PAHs are comprised of many different substances. Each substance acts upon the body in a similar fashion, but at differing intensities. To determine the toxicity of all the PAHs together, they can be summed by estimating their toxicity relative to a standard PAH, benzo(a)pyrene. The total benzo(a)pyrene equivalents in this sample is 9 mg/kg. At this concentration, there is a slightly increased risk of cancers of the stomach, esophagus, and larynx after a lifetime exposure. This increased risk of cancer is unlikely, however, because of the infrequency of people’s exposure to soil in this single area.
The most recent sampling information available from the US Army and the EPA do not indicate that adverse health effects might occur as a result of exposure to these soils. However, many of the suspected chemical warfare agents, laboratory reagents, and their degradation products were not analyzed for in the samples. Because of the volatile and reactive nature of many of these chemical warfare agents, it is not likely that much remains as soil contamination.
Chemical and conventional ordnance may remain buried at the American University or in the vicinity. In addition, laboratory or storage vessels may also be buried in these areas. These discarded weapons and glassware may hold explosives or noxious agents, and could pose serious health threats if they are unearthed.
Consideration should be made of the potential that suspected chemical agents and laboratory reagents may remain as soil contamination. ATSDR plans to develop a public health consultation which will address the environmental fate of these substances.
A focused health education program should be considered to inform the local “Call Before You Dig” utility hotline, poison control center, HazMat Team, unions, construction and utility firms, etc., about potential hazards.
US Environmental Protection Agency, Spring Valley Munitions Site Analytical Summary, 1994.
Dragun, James, and Andrew Chiasson, “Elements in North American Soils,” Hazardous Materials Control Resources Institute, Greenbelt, MD, 1991.
PREPARER OF REPORT
Dana Abouelnasr, Ph.D.
Senior Scientist, Office of Federal Programs
Agency for Toxic Substances and Disease Registry