The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an Exposure Investigation (EI) in March 2002, in cooperation with the Washington, D.C. Department of Health. The EI was conducted for those households that had the highest arsenic levels in composite soil samples taken from their yard. In this Exposure Investigation, 32 individuals (23 adults and 9 children) were evaluated for arsenic exposure and 13 homes were evaluated for arsenic content.

 Urine arsenic levels, which are a good measure of recent arsenic exposure, were low in the individuals tested.  These levels would not be expected to cause any health problems.  Individuals had their urine tested for inorganic arsenic (which could be coming from naturally-occurring arsenic or contaminated soil and dust) and total arsenic (which could come from all sources-food, water, air, soil and dust).  We measure arsenic in urine in parts per billion (ppb).  Only four of the individuals tested had detectable inorganic arsenic in their urine, with levels ranging from 10 ppb to 15 ppb.  Levels below 20 ppb of inorganic arsenic usually indicate no significant exposure. All individuals tested had total urinary arsenic between 0 and 210 ppb.  This value range is what one might expect in the general population.  The total urinary arsenic is mostly organic arsenic from food sources and is much less toxic than inorganic arsenic.

 Hair arsenic testing is not as accurate as urine testing, but allows us to look at arsenic exposure during the past months or years (depending on the length of the hair).  We measure arsenic in hair in parts per million (ppm).  All individuals tested had hair arsenic levels between 0 ppm and 0.73 ppm.  The average was 0.1 ppm.  Levels below 1 ppm usually indicate no significant exposure.  In summary, the hair arsenic levels show low levels of exposure.  These levels would not be expected to cause any health problems.

 Household dust was tested in 13 homes.  Levels of arsenic ranged from 0 ppm to 63 ppm.  The average was 9.9 ppm of arsenic in the dust.  It is difficult to interpre the significance of household dust levels.  However, it is apparent from the hair and urine tests that these levels are not causing elevated arsenic levels, or any increased health risks, to individuals in these homes.

ATSDR will continue to be involved in activities in the Spring Valley neighborhood.  Consideration is being given further arsenic testing if other individuals are identified who might be at risk for exposure.  Any further testing or evaluation will be discussed with the Spring Valley Scientific Advisory Panel, the Restoration Advisory Board, and the local community.