[CPEO-MEF] Possible vapor intrusion at Camp Lejeune (NC)

[Lenny Siegel <lennysiegel@gmail.com>]

When I first learned about the drinking water contamination at Camp 
Lejeune's (NC) Tarawa Terrace family housing area, I started asking: Was 
it possible for vapors from the groundwater plume of volatile organic 
compounds to intrude into overlying buildings? Eventually the Marines 
assured me that there was no vapor intrusion pathway.

Now, according to a July 2007 study by the Agency for Toxic Substances 
and Disease Registry (ATSDR), it turns out that there might have been a 
vapor intrusion problem impacting both homes and the elementary school 
at Tarawa Terrace. (See 
http://www.atsdr.cdc.gov/sites/lejeune/docs/ChapterA_TarawaTerrace.pdf)

I say "might" because the modeled groundwater contamination is 
relatively low directly beneath the homes and school. Depending upon a 
number of variables, exposures might have been too low to be detected. 
Nevertheless, the chance that vapor exposures continued after 
alternative drinking water was supplied, and that residents and students 
may have been subject to additive exposures from water and air, suggests 
that the any retrospective health study at Camp Lejeune look carefully 
at the possibility of vapor intrusion.

Page A41 states:

"Although exposure to contaminated drinking water was eliminated after 
February 1987 due to the closure of the Tarawa Terrace WTP during March 
1987 (Figures A3 and A18; Table A12), measurable quantities of PCE 
remained in the subsurface—at the source  (ABC One-Hour Dry Cleaners) 
and distributed within the aquifer (Figure A17b). For example, during 
July 1991, the PCE concentrations in water samples obtained from 
off-line water-supply wells TT-25 and TT-26 were 23 μg/L and 350 μg/L, 
respectively (Table A9). This mass of PCE in the subsurface continued to 
migrate and undergo transformation through physical and biochemical 
processes such as volatilization and biodegradation. As such, the 
potential for exposure to PCE and its degradation by-products TCE, 
1,2-tDCE, and VC from a route other than ingestion and inhalation of 
drinking water- such as inhalation of soil vapors -continued beyond 
cessation of exposure to drinking water after the closure of the Tarawa 
Terrace WTP in March 1987 (Figure A3."

Page A99 adds:

"Soil at Camp Lejeune is sandy, so the vapors can readily vaporize up to 
the surface. The buildings are on concrete slabs, so soil vapor can 
enter these buildings through cracks or perforations in slabs or through 
openings for pipes or wiring. In addition, because the vapor enters the 
building due to pressure differences, the operation of heating or 
air-conditioning systems can create a negative pressure in the building 
that draws the vapors from the soil into the building. This is similar 
to the situation with radon gas."

However, ATSDR concludes:

"The results of the PCE and PCE degradation by-product soil vapor 
modeling will not have a major impact on the current epidemiological 
study of specific birth defects (neural tube defects, cleft lip, and 
cleft palate) and childhood cancers (leukemia and non-Hodgkin’s lymphoma 
- also known as childhood hematopoietic cancers). The focus of the study 
is on drinking-water exposures to the fetus up to the child’s first year 
of life. The drinking-water exposure is considerably greater than any 
exposure that might occur due to soil vapor infiltration into a home. 
However, the analysis may incorporate the soil vapor results to 
determine if these exposures significantly change the results obtained 
from the analysis of drinking-water exposures."

This last part surprises me. I thought that people "breathe more than 
they drink" (even infants). But I'm not an epidemiologist.


Lenny
--


Lenny Siegel
Executive Director, Center for Public Environmental Oversight
a project of the Pacific Studies Center
278-A Hope St., Mountain View, CA 94041
Voice: 650/961-8918 or 650/969-1545
Fax: 650/961-8918
<lsiegel@cpeo.org>
http://www.cpeo.org



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