Skip directly to search Skip directly to A to Z list Skip directly to site content

PUBIC HEALTH ASSESSMENT

TRW MICROWAVE, INC.
(BUILDING 825)
SUNNYVALE, SANTA CLARA COUNTY, CALIFORNIA


CONCLUSIONS

ATSDR and CDHS have concluded, based on information reviewed, that TRW is not an apparent public health hazard (Category D). The only completed human exposure pathway is from inhalation by off-site residents of volatile organic compounds migrating into homes and other buildings in the area from shallow groundwater. This pathway was proposed based on extrapolations from groundwater concentrations to soil-gas vapors and from soil-gas vapors to indoor air concentrations using mathematical models. Studies conducted under the direction of CDHS indicate that the contaminated groundwater may contribute to the indoor air quality but not at a level of public health concern.

Future significant exposure to groundwater contaminants is unlikely if the groundwater extraction and treatment system reduces concentrations of site related contaminants to below levels of health concern. If groundwater remediation does not clean up contaminants to drinking water standards, no future drinking water wells should be placed in areas of known contamination.

The current exposure pathway of inhalation of VOC vapors from the off-site groundwater plume is the issue that raises the most community health concerns.


RECOMMENDATIONS

Recommendations previously made for this site have been implemented. Remediation of contaminated groundwater is on-going, and contaminated soils that could be removed have been. Indoor air quality has been studied, and levels of the VOCs are not at levels of public health concern. Deed restrictions are being implemented on the TRW property, as well as the other NPL sites contributing to groundwater contamination, to prevent installation of on-site drinking water wells. No authority has been identified to implement restriction of well installation on private property; however, the community is aware of the groundwater contamination, and no one is likely to install a drinking water well because of that knowledge and the fact that public water is available. No other recommendations for site characterization or environmental sampling have been identified.

ATSDR's Health Activities Recommendation Panel (HARP) evaluated the data and information in the TRW Microwave Public Health Assessment for follow-up health activities. HARP determined that although exposure to site contaminants may have occurred in the past and may be occurring now, environmental sampling data were not available to assess the magnitude and public health significance of the exposure. Community health education activities, however, are on-going and will continue to address specific community health concerns as they arise. When data become available, ATSDR and CDHS will reevaluate this site for any indicated follow-up health activities.

Since the time HARP made those determinations, environmental sampling data became available to assess exposures, and that data were evaluated. The levels of site-related VOCs that may be contributing to indoor air levels are not at levels of public health concern.


PUBLIC HEALTH ACTIONS

The Public Health Action Plan (PHAP) for the TRW Microwave site contains a description of actions to be taken by ATSDR and/or CDHS at and in the vicinity of the site subsequent to the completion of this public health assessment. The purpose of the PHAP is to ensure that this public health assessment not only identifies public health hazards, but provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The public health actions implemented by ATSDR or CDHS, or other agencies, are as follows:

  1. In the areas of known groundwater contamination, implement institutional controls to prevent future use of contaminated aquifers for drinking water supplies until remediation has reduced contaminant concentrations to below levels of health concern.
  2. As part of the agreed clean-up remedy (called the Record of Decision or ROD) each company, including TRW, will be placing a deed restriction on their own property (36). This restriction does address future well construction on that property. Apparently, no agency has the statutorial power to implement well-construction restrictions on the privately owned, off-site properties.

  3. Continue flux chamber measurements of VOC soil vapor release until the value of these data is determined.
  4. As directed in the ROD, the companies have conducted flux chamber measurements twice a year for the last two years (36). The need for this monitoring is being reevaluated by U.S. EPA and RWQCB.

  5. Request the Air and Industrial Hygiene Laboratory (AIHL) of CDHS to conduct indoor air sampling at the San Miguel School. Since commercial products found in homes contain some of these organic contaminants, school sampling may pose fewer problems as compared to residential homes in terms of "background" inventory.
  6. On August 20, 1991, the Health Investigation Branch within CDHS requested that AIHL conduct air sampling at San Miguel School and a control school for comparison. AIHL conducted indoor air sampling in San Miguel School and a control school, Cherry Chase School, in February 1992. Due to sampling problems, the sampling was repeated by the Bay Area Air Quality Management District in November 1992.

    The levels of the chemicals found inside the school are considered typical for indoor air. Levels that are considered typical for indoor air are based on studies of indoor air quality done throughout the United States and Europe.

  7. When flux chamber monitoring data and indoor air data is obtained, CDHS and RWQCB should then reevaluate the significance of the potential indoor air exposure.
  8. The RWQCB project manager for this site participated on the advisory committee for the indoor air sampling. Additionally, RWQCB is interested in better understanding this potential pathway. Based on the air sampling study results, CDHS does not believe that this pathway poses a public health hazard.

  9. Interpret and share results of indoor air sampling with concerned community.
  10. CDHS/ATSDR staff initiated the formation of a community-based advisory committee to oversee the workplans and interpretations of the school air sampling.

    The advisory committee included seven members of the community. CDHS presented the results of the AIHL air sampling at a community meeting in August 1992. The impact of the sampling problems was discussed with the community and CDHS promised to pursue a better resolution. The results of the BAAQMD air sampling carried out in November 1992 were presented in a fact sheet delivered by hand to the San Miguel neighborhood and also appear in this revision of the public health assessment.

  11. Continue to pursue the relevant Tumor Registry and Birth Defects Monitoring data.
  12. CDHS/ATSDR is no longer pursuing these data. The low level of chemical exposure that might arise from this site's contamination does not warrant further evaluation of those data.


PREPARERS OF REPORT

ENVIRONMENTAL AND HEALTH EFFECTS ASSESSORS:

Marilyn C. Underwood, Ph.D.
Toxicologist
Impact Assessment, Inc., Consultant to
Environmental Health Investigations Branch
California Department of Health Services

Diana Lee, M.P.H.
Research Scientist
Environmental Health Investigations Branch
California Department of Health Services

COMMUNITY RELATIONS COORDINATOR:

Jane Riggan, M.S.W.
Impact Assessment, Inc., Consultant to
Environmental Health Investigations Branch
California Department of Health Services

ATSDR REGIONAL REPRESENTATIVES

Gwendolyn Eng
William Nelson
Lynn Berlad
Regional Services, Region IX
Office of the Assistant Administrator

ATSDR TECHNICAL PROJECT OFFICER

Gail Godfrey
Environmental Health Scientist
Division of Health Assessment and Consultation
Remedial Programs Branch, State Programs Section


CERTIFICATION

The TRW Microwave, Incorporated, Site Public Health Assessment has been prepared by the California Department of Health Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health assessment was initiated.

Gail D. Godfrey
Technical Project Officer, SPS, RPB, DHAC


The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health assessment and concurs with its findings.

Robert C. Williams, P. E., DEE
Director, DHAC, ATSDR


REFERENCES

  1. Harding Lawson Associates, Engineering-Science, Inc., Emcon Associates, and Weiss Associates. Draft remedial investigation report, prepared for Advanced Micro Devices, Inc., Signetics Company, TRW, Inc. 1990. Sunnyvale, California.


  2. Clement Associates, Inc. Final baseline public health evaluation for the AMD/Signetics/TRW site, prepared for Advanced Micro Devices, Inc., Signetics Company, and TRW, Inc. 1990. Sunnyvale, California.


  3. Agency for Toxics Substances and Disease Registry. Preliminary public health assessment for Advanced Micro Devices, Inc. Cerclis No. CAD048634059. Sunnyvale, Santa Clara, California. U.S. Public Health Service-1989.


  4. Agency for Toxic Substances and Disease Registry. Public health assessment guidance manual. March 1992. U.S. Department of Health and Human Services.


  5. Bureau of the Census. Census of housing. U.S. Department of Commerce-1980.


  6. Department of Health Services. Cancer incidence and mortality. California, 1988. California Health and Welfare Agency-1991.


  7. California Department of Health Services and the March of Dimes Birth Defects Foundation. Birth Defects in California, January 1, 1983-December 31, 1986. January 15, 1990


  8. California Regional Water Quality Control Board. Fact sheet 2. Advanced Micro Devices 901/902, Signetics, TRW Microwave Superfund Sites. Sunnyvale, California. California Water Resources Agency-1991.


  9. California Regional Water Quality Control Board. Community relations plan for superfund sites in the city of Sunnyvale. Advanced Micro Devices/Signetics/FEI Microwave (TRW), Advanced Micro Devices Building 915, and Advanced Micro Devices (Arques). California Resources Agency-1990.


  10. Environmental Health Investigations Branch. Fact sheet-Indoor air sampling at San Miguel School. California Department of Health Services. August 1992.


  11. Environmental Health Investigations Branch. Fact sheet-Indoor air sampling at San Miguel School. California Department of Health Services. March 1993.


  12. Toxic chemical release inventory, TRI. Available on the National Library of Medicine's TOXNET on-line computer service, 1987. U. S. Environmental Protection Agency.


  13. Toxic chemical release inventory, TRI. Available on the National Library of Medicine's TOXNET on-line computer service, 1988. U. S. Environmental Protection Agency.


  14. Toxic chemical release inventory, TRI. Available on the National Library of Medicine's TOXNET on-line computer service, 1989. U. S. Environmental Protection Agency.


  15. Weiss Associates. Quarterly well monitoring report, fourth quarter 1990, prepared for TRW MIcorwave Inc. January 1991.


  16. Harding Lawson Associates. Quarterly report, fourth quarter 1990, prepared for Advanced Micro Devices Inc., Signetics Company, and TRW, Inc. 1991. Sunnyvale, California.


  17. Harding Lawson Associates. Annual and fourth quarter 1992 report, prepared for the Companies. January 28, 1993. Sunnyvale, California.


  18. Harding Lawson Associates. Results of shallow soil gas sampling, prepared for the Companies. June 12, 1991. Sunnyvale, California.


  19. Harding Lawson Associates. Soil flux monitoring, prepared for the Companies. July 27, 1992. Sunnyvale, California.


  20. Harding Lawson Associates. Soil flux monitoring, prepared for the Companies. January 25, 1992. Sunnyvale, California.


  21. Harding Lawson Associates. Soil flux monitoring, prepared for the Companies. July 1992. Sunnyvale, California.


  22. Chief, Environmental Epidemiology and Toxicology Program. Memorandum to the Chief of the Air and Industrial Hygiene Laboratory. August 20, 1991. California Department of Health Services.


  23. Air and Industrial Hygiene Laboratory, California Department of Health Services. Report- Quantitation of volatile organic compounds, Sunnyvale Schools Project. February 1992.


  24. Chief, Division of Environmental and Occupational Disease Control. Letter to the Air Pollution Control Officer of the Bay Area Air Quality Management District. July 29, 1992. California Department of Health Services.


  25. Air Pollution Control Officer. Letter to Chief, Division of Environmental and Occupational Disease Control, California Department of Health Services. August 12, 1992. Bay Area Air Quality Management District.


  26. Director of Technical Services. Letter to Toxicologist, Environmental Health Investigations Branch, California Department of Health Services. December 15, 1992. Bay Area Air Quality Mangement District.


  27. Acting Chief, Environmental Health Investigations Branch. Letter to the Air Pollution Control Officer of the Bay Area Air Quality Management District. August 20, 1992. California Department of Health Services.


  28. Air Pollution Research Specialist, Air and Industrial Hygiene Laboratory. Memorandum to toxicologist, Division of Environmental and Occupational Disease Control. California Department of Health Services.


  29. Little J.C., Daisy J.M., and Nazaroff W.W. 1992. Transport of subsurface contaminants into buildings: an exposure pathway for volatile organics. Environmental Science and Technology, 26(11):2058-2066.


  30. Agency for Toxics Substances and Disease Registry. Draft toxicological profile of tetrachloroethylene. U.S. Public Health Service-1991.


  31. Agency for Toxics Substances and Disease Registry. Toxicological profile for trichloroethylene. U.S. Public Health Service-1990. PB/90/127523/AS


  32. Agency for Toxics Substances and Disease Registry. Draft toxicological profile for 1,1,1-trichloroethane. U.S. Public Health Service-1989.


  33. Chief, California Tumor Registry. Personnel communication by Letter to President, Silicon Valley Toxics Coalition. May 21, 1991. California Department of Health Services.


  34. Epidemiologist, California Birth Defects Monitoring Program. Personnel communication by telephone-March 4, 1991. California Department of Health Services.


  35. McFarlane, C., Pfleeger, T., and Fletcher, J. 1990. Effect, uptake and disposition of nitrobenzene in several terrestrial plants. Environmental Toxicology and Chemistry, 9:513-520.


  36. U. S. Environmental Protection Agency. Record of decision - Advanced Micro Devices #901/902, Signetics, TRW Microwave. Sunnyvale, CA. September 11, 1991.


  37. Toxic Air Contaminant Section. Toxic Air Contaminant Reduction Plan. Bay Area Air Quality Management District. August 7,1991.


  38. Shah J.J. and Singh H.B. 1988. Distribution of volatile organic chemicals in outdoor and indoor air: a national VOCs data base. Environmental Science and Technology, 22(12): 1381-1388.


  39. Pellizzari E.D., Hartwell T.D., Perritt R.L., Sparacino C.M., Sheldon LS, Zelon H.S., Whitmore R.W., Breen J.J., and Wallace L. 1986. Comparison of indoor and outdoor residential levels of volatile organic chemicals in five U.S. geographical areas. Environment International, 12: 619-623.


  40. Stolwijk J.A.J. 1990. Workshop on indoor air quality: assessment of population exposure and carcinogenic risk posed by volatile organic compounds in indoor air. Risk Analysis, 10(1): 49-57.

APPENDIX A: TABLES

TABLE 1. VOCs IN SOILS ON THE FORMER TRW PROPERTY

  MAXIMUM CONCENTRATION (ppm)  
Outside Building Inside Building Comparison Value (ppm): Source Contaminant of Concern
Subsurface Aquitard Subsurface Aquitard
Vinyl chloride nd 3.2 nd nd 10:EMEG no
cis-1,2-Dichloroethylene 0.002 2.6 0.3 6.5 200,000: iEMEG no
Trichloroethylene 1.2 0.82 1.6 nd 60:CREG no
Tetrachloroethylene 0.7 nd 0.3 nd 10:CREG no
1,2-Dichlorobenzene 2.8 nd 1.8 nd 60,000:RMEG no
Data taken from the draft RI (1)
nd=not detected above detection levels


TABLE 2. TOTAL METALS IN SOILS ON THE FORMER TRW PROPERTY

  CONCENTRATION (ppm) Comparison Value (ppm): Source Contaminant of Concern
Acid Neutralization (7-8 ft.) Waste Solvent (6.5-1.9 ft.) Background (3 ft.)
Arsenic <0.5 1.4-4.6 0.6-2.6 0.4:CREG No
Beryllium 0.7-2.0 <0.2-0.5 <0.2 0.2:CREG Yes
Cobalt 17-39 6.1-13 5.1-13 -- Yes
Copper 30-190 25-30 11-22 -- Yes
Lead 33-66 7.9-11 <6 -- Yes
Mercury 0.2-0.6 0.03-0.1 <0.1 100:iEMEG No
Molybdenum 45-57 <2-3 <1.6 4000:RMEG No
Nickel 60-250 51-70 30-53 -- Yes
Vanadium 63-180 36-48 28-62 -- Yes
Data taken from the draft RI (1)


TABLE 3. SOLUBLE METALS FROM SOIL ON THE FORMER TRW PROPERTY

 
Soluble Concentration (ppm)
Barium
<6-40
Beryllium
<0.01-0.01
Copper
<10.0
Vanadium
1.0
Data taken from the draft RI (1)


TABLE 4. GROUNDWATER VOC CONTAMINATION AT THE TRW SITE

  Maximum Concentration in Each Aquifer (ppb) Comparison Value (ppb): Source Contaminant of Concern
A B1 B2
1,1,1-Trichloroethane 20 10 nd 200:US MCL No
Freon 113 nd 270 550 1200:CA MCL No
Vinyl chloride 3.3 7,800 nd 0.2:EMEG Yes
1,2-Dichloroethylene 930 52,000 16 6,10:CA MCL Yes
Trichloroethylene 1,400 19,000 4,200 3:CREG Yes
Tetrachloroethylene 4.3 17 nd 0.7:CREG Yes
1,2-Dichlorobenzene 3.4 nd nd 600:US MCL No
Data taken from a 1990 quarterly well monitoring report (15)
nd = not detected above detection limits


TABLE 5. METALS IN GROUNDWATER ON THE FORMER TRW PROPERTY

  Maximum Concentration in Each Aquifer (ppm) Comparison Value (ppm): Source Contaminant of Concern
A B1 B2 A-bkgd
Arsenic nd 0.006 nd nd 0.00002:CREG Yes
Barium 0.1 0.2 nd 0.07 0.7:RMEG No
Chromium 0.003 nd nd nd 0.05:US MCL No
Copper 0.034 nd nd 0.01 1.3:US MCL No
Lead 0.002 0.002 nd 0.002 0.05:RMEG No
Nickel 0.018 0.032 0.18 0.023 0.1:CA MCL Yes
Selenium 0.003 nd nd 0.005 0.03:EMEG No
Zinc 0.03 nd nd nd 3.0:RMEG No
nd=not detected above detection limits
Data taken from the draft RI (1)


TABLE 6. GROUNDWATER VOC CONTAMINATION OFF-SITE

  Maximum Concentration in each aquifer (ppb) Comparison Value (ppb): Source Comparison of Value
A B1 B2 B3 B4
Dichloromethane 6 8.9 10 nd 7.4 5:CREG Yes
Chloroform 11 2.6 65 0.3 0.4 6:CREG Yes
1,1-Dichloroethane 2.6 110 nd nd nd 5:CA MCL Yes
1,1,1-Trichloroethane 7 1700 76 nd 0.4 200:US MCL Yes
Freon 113 26 160 nd 200 15 1200:CREG No
1,1-Dichloroethylene 1.4 2.5 nd nd 2.8 0.06:CREG Yes
1,2 Dichloroethylene- 16 160 nd nd 1.4 6/10:CA MCL Yes
Trichloroethylene 530 2400 2400 68 68 3:CREG Yes
Tetrachloroethylene 1.2 nd nd nd nd 0.7:CREG Yes
nd=not detected above detection limits
Data taken from 1991 quarterly well monitoring report (16)


TABLE 7. METALS IN GROUNDWATER OFF-SITE

  Maximum Concentration in Aquifer Each (ppm) Comparison Value (ppm): Source Contaminant of Concern
A B1 B2 B3 B4
Arsenic nd nd nd nd 0.0 0.00002:CREG No
Barium 0.1 0.16 0.1 0.2 0.14 7:RMEG No
Manganese 0.27 0.31 0.7 0.23 0.13 0.05:CA MCL Yes
Selenium 0.021 0.0005 nd nd nd 0.03:EMEG No
Silver 0.01 0.01 nd nd 0.01 0.05:RMEG No
Zinc 0.05 0.09 0.07 0.02 0.03 3:RMEG No
nd=not detected above detection limits
Data are taken from the draft RI (1)


TABLE 8. OFF SITE SOIL GAS FLUX MEASUREMENTS

Sampling Location Date TCE PCE 1,2-DCB cis-1,2-DCE Freon 113 TCA VC
4 4/28/91 <0.26 <0.26 <0.26 <0.26 0.65 0.58 <0.26
7/27/91 <0.26 0.17 <0.26 <0.26 0.34 0.34 <0.26
1/25/92 <0.27 <0.27 <0.27 <0.27 0.29 0.66 <0.27
7/17/92 <0.13 <0.13 <0.13 <0.13 0.29 0.72 <0.13
6 4/28/91 <0.26 <0.26 <0.26 <0.26 0.95 0.56 <0.26
7/27/91 0.17 0.32 <0.26 <0.26 0.30 0.49 <0.26
1/25/92 <0.27 <0.27 <0.27 <0.27 0.61 0.71 <0.27
7/17/92 <0.13 <0.13 <0.13 <0.13 1.35 0.77 <0.13
7 4/28/91 <0.30 <0.30 <0.30 <0.30 0.13 0.18 <0.30
7/27/91 4.5 0.23 <0.23 <0.28 <0.28 0.52 <0.28
1/25/92 <0.26 <0.26 <0.26 <0.26 <0.26 0.29 <0.28
7/17/92 9.1 <0.14 <0.14 <0.14 <0.14 0.25 <0.14
8 4/28/91 <0.28 <0.28 <0.28 <0.28 0.16 0.25 <0.28
7/27/91 <0.26 0.19 <0.26 <0.26 <0.26 0.39 <0.26
  1/25/92 -- BAD SAMPLE VALVE OPEN --
7/17/92 0.21 <0.14 <0.14 <0.14 <0.14 0.38 <0.14
9 4/28/91 0.52 <0.28 <0.28 <0.28 0.23 0.31 <0.28
7/27/91 0.45 0.05 <0.10 <0.26 <0.26 0.24 <0.26
1/25/92 <0.27 <0.27 <0.27 <0.27 <0.27 0.45 <0.27
7/17/92 0.53 <0.13 <0.13 <0.13 <0.13 <0.13 <0.13
10 4/28/91 <0.26 <0.26 <0.26 <0.26 0.35 0.26 <0.26
7/27/91 <0.26 0.14 <0.26 <0.26 0.24 0.32 <0.26
1/25/92 <0.27 <0.27 <0.27 <0.27 <0.27 0.53 <0.27
7/17/92 <0.14 <0.14 <0.14 <0.14 0.17 1.1 <0.14
11 4/28/91 <0.28 <0.28 <0.28 <0.28 0.25 0.24 <0.28
7/27/91 <0.26 0.15 <0.26 <0.26 0.30 0.36 <0.26
1/25/92 <0.27 <0.27 <0.27 <0.27 <0.27 <0.46 <0.27
7/17/92 <0.14 <0.14 <0.14 0.26 <0.26 0.53 <0.14
Concentrations are expressed in parts per billion volume
Data taken from soil flux reports (19-22)


TABLE 9. AIR SAMPLING DATA AT SAN MIGUEL AND CHERRY CHASE SCHOOLS

Sampling Location Date
Sample
Completed
TCE PCE VC 1,1-DCE 1,2-DCE 1,1,1-TCA Benzene Ethyl-benzene Styrene m-Xylene
San Miguel Room B3 2/20/92
8/11/92
11/9/92
na
0.36
0.47
0.32
0.05
0.012
<0.3
<0.30
<2.0
0.19
<0.10*
<0.20*
0.10
<0.10*
<0.20*
0.53
1.67‡
2.32‡
2.50
1.0
3.3
0.73
na
na
0.13
na
na
2.64
na
na
San Miguel Room B4 2/20/92
8/11/92
11/9/92
na
2.63
2.37
0.24
0.10
0.13
<0.3
<0.30
<2.0
0.38
<0.10*
<0.20*
<0.10
<0.10*
<0.20*
0.42
1.25‡
1.32‡
1.21
1.2
3.0
0.37
na
na
0.07
na
na
1.51
na
na
Cherry Chase
Room 14
2/20/92
8/11/92
11/9/92
na
<0.08
<0.08
0.26
0.11
0.14
<0.3
<0.30
<2.0
0.34
<0.10*
<0.20*
<0.10
<0.10*
<0.20*
0.54
0.49‡
0.71‡
0.61
0.63
1.5
0.17
na
na
0.02
na
na
0.61
na
na
San Miguel Outside 2/20/92
8/11/92
11/9/92
na
<0.08
<0.08
0.43
0.11
0.02
<0.3
<0.30
<2.0
0.31
<0.10*
<0.20*
<0.10
<0.10*
<0.20*
0.67
0.57
0.24‡
1.10
1.0
0.50
0.49
na
na
0.22
na
na
1.67
na
na
Cherry Chase Outside 2/20/92
8/11/92
11/9/92
na
<0.08
<0.08
0.16
0.38
0.29
<0.3
<0.30
<2.0
0.11
<0.10*
<0.20*
<0.10
<0.10*
<0.20*
0.23
0.48‡
0.40‡
0.25
1.3
0.40
0.21
na
na
0.01
na
na
0.74
na
na
Mountain View BAAQMD station 2/19/92
8/11/92
11/9/92
<0.08
<0.08
<0.08
0.08
0.44
0.46
<0.03
<0.30
<2.0

<0.10*
<0.10*
<0.20*

<0.10*
<0.10*
<0.20*
0.23‡
0.39‡
0.25‡
1.4
1.5
0.9
na
na
na
na
na
na
na
na
na

Air concentrations are expressed in parts per billion volume (ppb) of the first air sample of the day-with the windows and doors closed and the exhaust system turned off.
*=BAAQMD quantitates these compounds together as dichoroethylene.
‡=BAAQMD quantitates the trichloroethane isomers together.
na = not available
Data taken from air sampling records (23,25,26).


TABLE 10. AIR SAMPLING AT SAN MIGUEL AND CHERRY CHASE SCHOOLS DURING DIFFERENT VENTILATION MANIPULATIONS

Sampling Location Ventilation conditions TCE PCE TCA‡ Benzene Air Exchange per Hour Pressure Differential Reading (Pasquals)
San Miguel Room B3 Closed up / no exhaust
Closed up / with exhaust
Open wide / with exhaust
0.47
0.42
<0.08
0.12
0.04
0.09
2.32
0.38
0.56
3.3
0.45
0.60
0.3
2.3
9.3
-9
-26
0
San Miguel Room B4 Closed up / no exhaust
Closed up / with exhaust
Open wide / with exhaust
2.37
1.28
0.10
0.13
0.04
0.07
1.25
0.38
0.49
3.0
0.70
0.55
0.2
1.5
4.4
-10
-17
0
Cherry Chase Room 14 Closed up / no exhaust
Closed up / with exhaust
Open wide / with exhaust
<0.08
0.15
<0.08
0.14
0.09
0.05
0.71
0.80
0.27
1.5
0.50
0.40
0.2
4.2
15.0
--
-15
0
San Miguel Outside (Closed up / no exhaust)
(Open wide / with exhaust)
<0.08
<0.08
0.02
0.09
0.24
0.49
0.50
0.50
--
--
--
--
Cherry Chase Outside (Closed up / no exhaust)
(Open wide / with exhaust)
<0.08
<0.08
0.29
0.06
0.39
0.27
0.40
<0.20
--
--
--
--
Mountain View Station
--
<0.08 0.46 0.25 0.90
--
--
--
--

Air concentrations expressed in parts per billion volume (ppb) from sampling conducted on November 9, 1992.
No vinyl chloride (nd= 2.0 ppb) or dichloroethylene (nd=0.10 pb) was detected in any of the samples.
‡=BAAQMD quantitates the trichloroethane isomers together.
BAAQMD did not quantitate the concentration of ethylbenzene, styrene, or m-xylene in the samples.
Data taken from air sampling records (26,28).


TABLE 11. ACTION LEVELS FOR AIR SAMPLING AT SAN MIGUEL SCHOOL

INTERPRETATION OF CONCENTRATIONS
(ppbv) AND ACTION RECOMMENDED
TCE PCE Vinyl
Chloride
1,1-DCE 1,2-DCE 1,1,1-TCA Benzene Ethyl
Benzene
Styrene Xylenes
Level I. Concentrations found within this range are considered typical for indoor environments. No further action recommended. <5.00 <4.00 <0.00 <1.00 ? <20.00 <12.00 <10.00 <5.00 <10.00
Level IIa. Concentrations found within this range are considered typical for indoor environments. Maximum exposure to these concentrations may lead to adverse health effects. Additional sampling under typical conditioins may be warranted. >3.05 &
<5.00
    >0.46 &
<1.00
    >3.28 &
<12.00
     
Level IIb. Concentrations within this range are elevated compared to a typical indoor environment. These concentrations are not necessarily associated with adverse health effects. Repeat sampling with further sampling refinement such as daytime/nightime sampling; more sampling locations with the school.   4.01 - 12.50 0.2 - 2.0     20.01
300.00
  10.01 -
300.00
5.01 -
50.00
10.01 -
100.00
Level III. Concentrations within this range are elevated compared to a typical indoor environment. Exposure to these concentrations may lead to adverse health effects. Discontinue use of school. Conduct extensive sampling in school to confirm results. If concentrations are confirmed, immediate remedial action should be taken to reduce levels to the Level III range. Sample in nearby homes and control homes. > 5.0 >12.5 >2.00 > 1.0 >200.00 >300.00 > 12.00 > 300.00 > 50.00 > 100.0

See Appendix C for details


APPENDIX B: FIGURES

Three Company Site and Associated Study Area
Figure 1. Three Company Site and Associated Study Area

Surface Emission Isolation Flux Chamber Sample Location Map
Figure 2. Surface Emission Isolation Flux Chamber Sample Location Map

Interpretation Scheme for San Miguel School Air Sampling Results
Figure 3. Interpretation Scheme for San Miguel School Air Sampling Results

Analysis of November 11, 1992 Air Sampling Using Interpretation Flowchart
Figure 4. Analysis of November 11, 1992 Air Sampling Using Interpretation Flowchart


APPENDIX C: DEVELOPMENT OF THE INDOOR AIR STUDY

The Environmental Health Investigations Branch (EHIB) of the California Department of Health Services (CDHS) collaborated with the Air and Industrial Hygiene Laboratory (AIHL) within CDHS and the Bay Area Air Quality Management District (BAAQMD) to investigate this potential migration of VOCs from the groundwater into San Miguel School. Prior to the air sampling, EHIB developed an advisory committee composed of community members (neighborhood residents and San Miguel School representatives), a company representative, and various government agencies (Regional Water Quality Control Board (RWQCB), AIHL, and EHIB). The committee met four times prior to the sampling. At these meetings, the committee: a) focused the purpose of the indoor air study; b) oversaw the sampling design; and c) reviewed the source interpretation flowchart and action level table.

  1. Purpose of the indoor air study:
  2. To determine if the levels of VOCs measured inside San Miguel School are higher than levels typically reported for indoor air.

  3. Sampling design:
  4. There are three potential source contributions to chemicals indoor air: outdoor air, products within the building, and soil-gas.

    1. In order to identify the influence of the outdoor air on the indoor air quality, it was imperative that the outdoor air be sampled at the same time that the indoor air was sampled.


    2. The contribution from products within the building was accounted for in two ways: first, EHIB and AIHL staff inventoried the art supplies and cleaning products used in San Miguel School. They found that none of these items theoretically contained VOCs found in the contaminated groundwater. Secondly, the study design included sampling at another school (Cherry Chase School) of similar construction and age. An inventory at Cherry Chase School by EHIB and AIHL staff revealed that similar art supplies and cleaning products were used at both schools, probably due to them both being within one school district's purchasing blanket. Thus the "background" from products within the buildings should be similar at both schools. Most importantly Cherry Chase is not located over any groundwater plume.


    3. The soil gas contribution to indoor air quality was examined by comparing indoor and outdoor concentrations at San Miguel School to indoor and outdoor concentrations at Cherry Chase School. The "background" from indoor sources was thought to be similar and outdoor contribution was measured. There is no contribution from the soil gas at Cherry Chase School since it does not lie overtop of a contaminated groundwater plume like San Miguel School does.
    4. Secondly, the soil gas contribution can be maximized by depressurizing the room. The study was designed so that the first indoor air sample were taken in the rooms after they had not been used for two days. The windows and doors were kept shut and no ventilation was in operation. The concentrations of the compounds in this sample would reflect a combination of chemicals from the outdoor air (this is measured directly), the soil-gas (since there is a small depressurization in this scenario), and the products from within the building. Another sample is taken after depressurizing the room by keeping the windows and doors shut and turning on the exhaust system. The contributions of chemicals from the outside and from within the building are relatively unchanged whereas the increased depressurization maximizes the soil-gas entering the rooms.

    AIHL and BAAQMD sampled at two indoor locations (Rooms B3 and B3) and one outdoor location at San Miguel School and one indoor (Room 14) and one outdoor location at Cherry Chase School. AIHL had two mobile gas chromatograms which were needed to evaluate the ventilation rates within a room. One of these setups was used at San Miguel School (Room B3) and the other at Cherry Chase School. AIHL measured depressurization in all three rooms using a micromanometer.

    AIHL analyzed the air samples for six site-associated contaminants: trichloroethylene (TCE), tetrachloroethylene (PCE), vinyl chloride (VC), 1,1-dichloroethylene (1,1-DCE), 1,2-dichloroethylene (1,2-DCE), and 1,1,1-trichloroethane (1,1,1-TCA) and four compounds not found in the contaminated groundwater but typically found in indoor air (benzene, ethylbenzene, styrene, and xylenes). In essence these four non-site associated compounds were "positive" controls meaning if San Miguel School has typical indoor air quality then we would expect to find these other compounds as well. BAAQMD analyzed the air samples for trichloroethylene, tetrachloroethylene, dichloroethylene, 1,1,1-trichloroethane, vinyl chloride, and benzene.

    BAAQMD operates an air monitoring system in the San Francisco Bay area for some of the study compounds. The air monitoring data from the nearby Mountain View and San Jose stations were obtained to assess whether the outdoor concentrations at both schools were typical for regional air.

  5. Source interpretation flowchart and action level table:
  6. No air quality standards exist for the study compounds in the outdoor air or the indoor air. However, the study compounds are typically found in the outdoor air in urban settings and in indoor air. The outdoor air can be one of the sources of compounds found indoors. However, commercial cleaning products, art supplies, building materials, etc. are also known to contribute to the presence of many VOCs in indoor air. Additionally, radon studies have demonstrated that soil gas may contribute significantly to indoor air.

    Using their monitoring station data, BAAQMD have demonstrated that Bay Area Outdoor air contains chemicals at levels that are of health concern (38). Studies have also demonstrated that VOCs are typically found at greater concentrations indoors than outdoors (39-41).

    Prior to collecting air samples, two tools were developed to assist in interpreting the results: a flowchart to assist with source identification and an action level table to define public health action to be taken.

    The flowchart involves four different comparisons of the data which help elucidate the primary source of the levels of these compounds in the indoor air (Figure 3). Level A comparison establishes that the outdoor concentration at San Miguel School is typical for the region. Level B comparison examines the impact that the outdoor air may be having on the indoor air. Level C comparison utilizes the comparison school to initially examine the influence the contaminated groundwater may be having on San Miguel School. Level D comparison further investigates the influence that the soil-gas from the contaminated groundwater may be having on the indoor air. This comparison uses the indoor to outdoor concentration ratio with and without depressurization.

    The data were evaluated using the Action Level Table (Table 10). The Action Level Table was developed to address the possibility that the study compounds may be detected at concentrations that warrant further public health action. Health concerns are the most critical basis for deciding further actions to be taken. The health risk for trichloroethane, considered to a be a noncarcinogen, was based on ATSDR's Minimal Risk Level (33). The levels of health concern for the other compounds (trichloroethylene, tetrachloroethylene, 1,1-dichloroethylene, and benzene), which are considered to be carcinogenic, was the low (1 in 10,000) increased cancer risk if that concentration was inhaled for 24 hours per day 365 days per year for 75 years.

    Secondly, further action was also based by framing the detected concentrations within what is considered typical for indoor air. Typical levels were defined using the 75 to 90% levels reported in the scientific literature (39-41).


APPENDIX D: ANALYSIS OF THE NOVEMBER 1992 INDOOR AIR SAMPLING AT SAN MIGUEL SCHOOL

On November 9, 1992, the Bay Area Air Quality Management District (BAAQMD) sampled the indoor and outdoor air at San Miguel School and the indoor and outdoor air at Cherry Chase School and the outdoor air at their monitoring station in Mountain View. The Air and Industrial Hygiene Laboratory (AIHL) within CDHS measured the ventilation rates and depressurization of the school rooms. Three different ventilations scenarios were studied: indoors and windows closed, exhaust system turned off; doors and windows closed, exhaust turned on; doors and windows open, exhaust system turned on.

The November 1992 data (Table 10) was first evaluated using the interpretation flowchart developed with oversight from the neighborhood advisory committee (Figure 4).

Level A:

Compare concentration outdoors (0) near test school to concentration measured regionally (R) and in other urban settings.

Vinyl chloride and dichloroethylene (1,1-dichloroethylene and 1,2-dichloroethylene) were not detected outdoors at either school (0=nd) or at the Mountain View BAAQMD station, thus these compounds were "not a site-related or regional concern."

None of the study compounds were detected San Miguel School at concentrations substantially greater than at the Mountain View BAAQMD station (R<0), therefore none of the chemicals were referred to BAAQMD.

The concentrations of trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, and benzene detected at the Mountain View BAAQMD station were greater or approximately the same as the concentrations detected outside San Miguel School (R>0), therefore these compounds were carried onto Level evaluation.

Level B:

Compare test school indoor concentration (I) to outdoor concentration (0).

The ratio of the concentration of benzene detected indoors (I) was greater than the concentration measured outside and since this compound is not found in the groundwater (I/0 > 2 and not site associated), it appears that "an indoor source is contributing to the indoor air level of this compound."

None of the outdoor concentrations of the study compounds, were greater or equal to the indoor concentration (I/0 =2), thus leading to the conclusion that "groundwater contamination beneath the school is not affecting the test school."

The concentrations of three site-associated compounds - trichloroethylene, tetrachloroethylene, and 1,1,1-trichloroethane-inside San Miguel School are greater than the outdoor concentrations (I/0 >2 and site-associated) and therefore these compounds passed to Level C evaluation.

Level C:

Compare test school indoor concentration (I) to control school concentration (C5).

The concentrations of tetrachloroethylene measured inside Room B3 and B4 or the concentration of 1,1,1-trichloroethane measured inside Room 4 at San Miguel School is approximately equal or less than the concentration of that chemical inside the control school (I/CS < 2). Therefore, for these compounds and locations "groundwater contamination beneath the school is not affecting the test school."

The concentration of trichloroethylene or benzene measured inside Room B3 and B4 or the concentration of 1,1,1-trichloroethane in Room B of San Miguel School (I) is greater than the concentration of that chemical inside the control school (I/CS>2) and therefore these compounds and locations were passed to Level D evaluation.

Level D:

Comparison of indoor readings without ventilation (AM) with indoor readings with ventilation (PM) (see Table 11).

The indoor concentration detected with the windows and doors closed and the exhaust system off divided by the outdoor concentration of that chemical is termed "AM". The indoor concentration detected with the windows and doors closed and the exhaust system operating divided by the outdoor concentration of that chemical is termed "PM".

The indoor concentrations of tetrachloroethylene, 1,1,1-trichloroethane, and benzene are greater than the outdoor concentrations with the ventilation system off (AM>2) but when the ventilation system is on and the windows and doors are closed, the indoor and outdoor concentrations are essentially the same (PM = 1). This indicates that "indoor sources are the primary source of the indoor air concentration" of tetrachloroethylene, 1,1,1-trichloroethane, or benzene.

None of the study compounds followed the pattern where the indoor concentration and outdoor concentration were essentially the same in both ventilation situations (AM = 1 and PM = 1).

The indoor concentration of trichloroethylene is greater than the outdoor concentration, whether or not the ventilation system is operating with the windows and doors are closed (AM>2 and PM>2). This indicates that "groundwater contamination beneath test school is the primary source of the indoor air concentration" of trichloroethylene inside San Miguel School.

The action table that was developed with oversight from the advisory committee was used to interpret the concentrations of the study compounds detected inside San Miguel School (Table 10). The action table takes into account the potential toxicity and the typical indoor concentrations of these compounds. None of the study chemicals were detected at a level of public health significance and all of them were detected at levels considered typical for indoor air (Level 1 in Table 10). Thus "no further action is recommended."


APPENDIX E: SUMMARY OF RESPONSE DURING PUBLIC COMMENT PERIOD

TRW Inc. and their consultants, Weiss Associates submitted comments together during the public comment period (march 18 to April 23, 1993). They had a number of editorial comments which have been incorporated in this draft and the following general comments which CDHS has responded to:

TRW: It is not clear why higher indoor than outdoor concentrations under the "depressurization" scenario (PM>2) are necessarily indicative of contamination from ground water. In fact, using this reasoning would lead one to believe that the TCA detected in Cherry Chase Room 14 (Table 10) is indicative of low level ground water contamination, while it is known that no ground water contamination exists under this school. It seems that active indoor sources could produce the same results as contaminated ground water under this depressurization scenario.
RESPONSE:

The interpretation scheme (Figure 3) was created to compare the results of indoor air measurements within San Miguel School, the test school, to other relevant air measurements including Cherry Chase School, the control school. It was not designed to for use in analyzing the Cherry Chase indoor air results. However, it may be helpful to do so.

At Level A, the outdoor concentrations at Cherry Chase School is approximately equal to the regional concentration of TCA therefore there is no conclusion and the compound flows to the next level of comparison.

At Level B, the indoor to outdoor concentration is compared. The indoor concentration of TCA divided by the outdoor concentration is less than 2 at Cherry Chase School and the conclusion is that the groundwater contamination beneath the school is not affecting the school.

At Level C comparison, the concentration of TCA detected inside the test school is supposed to be compared to the concentration inside the control school. However this comparison cannot be made for Cherry Chase because there is no control school (or third school) for comparison.

At Level D, the indoor to outdoor concentration ratio with the windows and doors closed and the ventilation off (termed the AM ratio) and the indoor to outdoor concentration ratio with the windows and doors closed and the ventilation on (termed the PM ratio) are evaluated. For TCA at Cherry Chase School, both the AM and PM ratios are approximately 2 or less. According to the interpretation scheme this indicates that both indoor sources and outdoor air are probably the primary sources for TCA inside Cherry Chase School.

TRW: No explanation is provided for the fact that TCE concentrations in San Miguel Room B4 are consistently higher than in Room B3, while other compounds are present at about the same concentrations. If this TCE is originating from ground water, these indoor concentration differences should be related to some difference in the TCE distribution in ground water or in the diffusion and/or accumulation processes. No such differences are apparent from the information provided.
RESPONSE: The movement of soil gas into a building is not necessarily and most probably will not be constant over the entire surface of a slab foundation. Soil gas typically penetrates most readily through cracks in the foundation or where utilities penetrate the foundation. Thus the concentration differences of TCE inside Room B4 as compared to Room B3 are most likely due to differences in the ability of the soil gas to penetrate the foundation. However, the indoor air study did not include an engineer's examination of the integrity of the foundation.
TRW: The data indicate that PCE, TCA and benzene in indoor air at the San Miguel School originate from indoor sources. However, no identified sources of these compounds are mentioned in this report. If known or suspected sources were identified, it would be useful to present them. If potential sources were not identified, this fact in combination with the points discussed under #1 and #2 above suggests that the TCE detected in San Miguel School may represent an indoor source rather than ground water contamination.
RESPONSE:

The study design included testing at a control school because a complete listing of indoor sources at San Miguel School would be impossible. Cherry Chase School was chose as the control school because it was of similar design and construction to San Miguel School and many of the same cleaning and art supplies which are bought by the district are the used at both schools.

The commercial products used at San Miguel School and Cherry Chase School were inventoried by staff from the California Department of Health Services. Most of the products were indeed identical with one of the exceptions being an ant and roach killer found at San Miguel School but not at Cherry Chase School. The formulation of this particular ant and roach killer does contain TCA. This may explain why TCA was found at higher concentrations at San Miguel School than at Cherry Chase School.

The sources of the very low levels of tetrachloroethylene (PCE) detected in both schools are not known. The benzene emissions may have arisen from consumer products (paints, adhesives, marking pens, rubber products, and tapes) and/or off-gassing from particle board.

Table of Contents

  
 
USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

A-Z Index

  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #