PUBLIC HEALTH CONSULTATION
Assessment of Soil Sampling Results at the American University Child Development Center Washington, DC
December 14, 2000
During World Wars I and II, the US Army 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 buried in the area. Since that time, the affected area has been developed, and is now residential.
The Army has identified a suspected disposal area on the western boundary of the American University. Because of concerns about potential soil contamination in the area, the Army sampled soils on the playground of a nearby daycare, the American University Child Development Center.
The US Army Corps of Engineers has requested ATSDR to review the environmental sampling data from the daycare playground, to determine whether there is an increased risk of adverse health effects to the children, their families, and the teachers.
The Army sampled six areas within the playground, and mixed all six into a single soil sample. This sample was analyzed, and found to contain 31 mg/kg arsenic. This value is an average of all six samples, and does not provide any information about the distribution of the arsenic across the playground; it does not indicate whether the entire playground is at this level, or if there is one or more area which is more elevated than the others. The Army plans to address this issue through additional soil sampling in the play area.
For the purpose of this analysis, all of this arsenic is assumed to be in its most toxic form, which is inorganic arsenic. This assumption is consistent with the suspected source of the arsenic.
The American University Child Development Center serves children from ages 2½ to 6 years old. ATSDR estimates that children in this age group ingest around 200 mg of soil every day. Adults are estimated to ingest half this amount. Soils are ingested through several means, such as by eating with dirty hands, or placing dirty hands in the mouth. Soils may also be ingested as inhaled dusts, which are cleansed from the lungs and disposed of in the esophagus. Also, some very young children may purposely eat large amounts of soils.
There are several ways that children may come into contact with the soils in the play area. The area contains a garden for the children, where children may receive the most direct contact with the soil while gardening. Children may also dig in the soil throughout the area, although the area is covered with grass. The grass cover also limits the amount of dust that may become airborne and subsequently inhaled.
In this setting, a child whose weight is estimated at 10 kg (22 pounds) or larger would not ingest a large enough amount of arsenic to cause adverse health effects. However, should the same-size child purposely eat large amounts of soil (perhaps a handful), he or she could ingest sufficient amounts of arsenic to cause nausea, diarrhea, and abdominal cramps. Should the child eat large amounts of soil every day over a period of a few weeks, he or she could develop other symptoms, such as spots on their palms or the soles of their feet, which have either less or more pigmentation than the surrounding skin. These spots could be the precursor to the dark-colored warts or corns that are characteristic of large exposures to arsenic. These areas of darkened, thickened skin may themselves become precursors to skin cancer. However, the risk of developing skin cancer for a child who has often eaten a handful of this soil is comparable to the risk derived from eating the same amount of native soils.
Other cancers have also been associated with ingesting arsenic in drinking water, including cancers of the bladder, kidney, liver, and lung. However, arsenic in drinking water is much more readily absorbed from the gastro-intestinal tract than is arsenic from soils. For this reason, the risk of developing these cancers is not elevated from being exposed to these soils.
Adults and older children, who tend to ingest less soil than young children, and who are much larger in size, would be exposed to much less amounts of arsenic, and should not experience any adverse health effects, including cancer, from exposure to these soils.
Children attending the daycare, their families, and teachers, should not experience any adverse health effects from exposure to arsenic in soils at the level found by the Army. However, should children eat large amounts of soils (a handful a day), they may experience gastrointestinal distress. Also, if this behavior continues over a period of a few weeks, children may begin developing pigmentation changes on their palms and the soles of their feet.
The distribution of arsenic in the play area has not been determined. There may be small areas with higher concentrations of arsenic.
Children should be well supervised, to ensure that they do not purposefully ingest large amounts of soil.
Children should be discouraged from gardening or digging in the soils, until the soils have been sampled further.
Children and adults should wash their hands after coming in from the play area.
ATSDR concurs with the Army’s plan for additional sampling of the play area over a 20 foot grid. In addition, any areas where the children are more likely to contact the soils, such as the garden, should be included in the sampling efforts.
ATSDR will review the resulting environmental data to further evaluate the potential for adverse health effects to the children, their families, and teachers.
PREPARER OF REPORT
Dana Abouelnasr, Ph.D.
Senior Scientist, Office of Federal Programs
Agency for Toxic Substances and Disease Registry
phone: (404) 498-0684
toll free: 1-888-422-8737