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HEALTH CONSULTATION

RESPONSE TO LOS ANGELES UNIFIED SCHOOL DISTRICT
ABOUT POSSIBLE EXPOSURES AT PARK AVENUE SCHOOL
8020 PARK AVENUE
CUDAHY, LOS ANGELES COUNTY, CALIFORNIA


SUMMARY

The California Department of Health Services (CDHS) Environmental Health Investigations Branch (EHIB) was requested by the Los Angeles Unified School District (LAUSD) to evaluate the potential health concerns from soil gas exposures at the Park Avenue Elementary School. Because of the concern for exposure to school children, it was necessary to get a rapid response to the school district. EHIB staff wrote a letter to the school district in early March 2000 ( Appendix). The letter is the basis of this health consultation.


BACKGROUND AND STATEMENT OF ISSUES

The Park Avenue School was built in 1968. Starting in 1968 until cleanup occurred in 1990, a black-tar like substance would surface and would pool on asphalt-paved areas of the school yard during hot summer months. An investigation into the origin of the material by LAUSD determined that the Vloedeman Dump/B.H. Steepleton Landfill had operated at, and adjacent to, the school yard from the 1920's to the 1950's. Apparently, these landfills received refuse and petroleum wastes. Petroleum wastes were deposited in two large sumps located on and near the school property. LAUSD conducted an investigation of the tar-like substance and the extent of contamination. The contamination consisted of polycyclic aromatic hydrocarbons (PAHs), benzene, other volatile organic compounds, and lead. In 1990, LAUSD removed 2,400 cubic yards of petroleum contaminated soil from the bungalow and parking lot areas (southern border of the property). A passive vent system consisting of a series of perforated pipes was buried 10 feet below the surface of the turf area and the playground area, with three vent stacks located at the western edge of the property. The vent stacks released the untreated soil gas from a 4" pipe approximately 10 feet above ground. The playground and turf areas are capped with a cover to prevent contact with the subsurface soil.

Since the cleanup, LAUSD has conducted periodic soil vapor sampling from five vadose zone wells located throughout the school property (essentially soil borings that capture the soil gas from 1 to 2 foot below the surface), the vent system, and ambient air. The samples were analyzed for volatile organic compounds including aromatic hydrocarbons. The review of that data is the basis of this health consultation. The data is summarized in Table 1 in the Appendix.


DISCUSSION

Review of historical data (1990 & 1991)

The soil gas/air monitoring that was collected in 1990 and 1991 included both an ambient and upgradient grab sample and eight-hour sample collections. The upwind sample was reportedly collected to the northwest of the site. The upwind and on-school samples had very similar levels of dichlorofluoromethane, 1,1,1-trichloroethane (1,1,1-TCA), benzene, toluene, and xylenes. This seems to indicate that the soil gas is not affecting the air quality on the school property. In addition, the levels of these chemicals are typical for urban air [1]. During this time period, low levels of dichlorodifluoromethane, 1,1,1-TCA, benzene, toluene, and xylenes, were present in the air collected from the vents. Since these gases are released at the property line, soil gas probably has had little, if any, effect on the air quality in the school property. This is most likely due to the placement of the soil gas vents on the east side of the school property, such that the wind blowing predominantly west to east would disperse the soil gas from the vents away from the school property. During this same time period, low levels of dichlorodifluoromethane, 1,1,1-TCA, benzene, toluene, methyl ethyl ketone, methylene chloride, toluene, and xylenes were detected in the air collected from the vadose wells. However, the air sampling indicates that the cap/asphalt cover appears to be doing an adequate job at preventing the soil gas from migrating out from underneath the cap/asphalt cover and affecting the air quality.

Review of more recent data (1996-2000)

Most of the sampling events since May 1996 included analyses for a large number of chemicals and had appropriately low enough detection limits. This allows for a better understanding of the variety and levels of chemicals in the soil gas and ambient air. However, because no upgradient ambient air was collected, it is difficult to make a clear statement about the impact of the soil gas on the ambient air on the school property. The ambient air collected on the school property during this time period contained several VOCs that are typically found in outdoor air [1]. The levels measured on the school property are generally within the range of typical Los Angeles air; thus indicating that the ambient air is not unusually influenced by the possible residual contamination. The tetrachloroethylene (PCE) levels from the samples collected on 1/27/00 and 6/23/99 appear to be greater than one would expect for typical Los Angeles air. Interestingly, PCE was not detected (with low detection limits) in the outdoor air in the 90/91 monitoring. Since this observation is based on only two recent samples, the importance of this should be followed over the next few years. Though there is PCE in the soil gas, the levels in the soil gas would not seemingly provide a large enough source for the amount of PCE measured in the ambient air. It may be important to again conduct an upgradient ambient air sampling as was done in the past. This might help to determine if there is an upwind source of the PCE.

Health concerns of the ambient air and soil gas.

There are no regulatory standards or guidelines for volatile compounds in the subsurface soil zone that relates to breathing zone levels. Therefore, in order to evaluate the data, we assumed a worst-case scenario, that the constituents/concentrations of chemicals in the vent stacks are being breathed by someone. Assuming someone is breathing the vent gas is akin to someone sitting next to a hypothetical break in the cap and would be breathing the gases coming up through that hole. This, in a sense, is similar to the possible scenario that the community is concerned about, the release of vapors through the cap and into the surrounding air.

The chemicals detected in the ambient air and the three vents in sampling collection data, on 6/23/99 and on 1/27/2000, were evaluated for non-cancer health impact. Several of the chemicals detected in the ambient air and soil gas are considered to be carcinogenic. Thus, these chemicals were also evaluated for their possible carcinogenic effects (see below). None of the levels of the chemicals measured in the ambient air or vented soil gas exceed the non-cancer health comparison values (USEPA's Reference Concentration (RFC), or ATSDR's Minimal Risk Level (MRL)). The RFC or MRL is defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups like children) that is likely to be without appreciable risk of deleterious non-cancer health effects during a lifetime. Thus, the chemicals present in the air or the soil gas vent stacks would not be expected to cause non-cancer health effects.

Several of the chemicals detected in the ambient air and soil gas are considered to be carcinogenic based on human and animal studies. The total cancer risk for a lifetime of breathing the low levels of 1,1-dichloroethylene (1,1,-DCE), benzene, carbon tetrachloride, trichloroethylene (TCE), 1,1,2-trichloroethane (1,1,2-TCA), and PCE ranged between 9 to 15 in 10,000 (Appendix). This is considered a low cancer risk. This is very comparable to the cancer risk that the South Coast Air Quality Management District estimated for typical Los Angeles air. Thus, the ambient air and soil gas poses a cancer risk that is similar for the Los Angeles air.


CHILD HEALTH INITIATIVE

ATSDR and CDHS recognize that infants and children may be more sensitive to exposures than adults in communities with contamination in their water, soil, air, or food. Exposures to children were of primary concern in the analysis of the soil gas and ambient air levels that were measured on the Park Avenue School property.


CONCLUSIONS

The ambient air at the Park Avenue School seems to be relatively unaffected by any residual contamination in the soil on-site. The ambient air and soil gas would not be expected to result in non-cancer health effects. The ambient air and soil gas poses a low increased cancer risk, similar to the risk posed by typical Los Angeles urban air.

These conclusions could be stated with more confidence if better air monitoring had been conducted in the past. EHIB and ATSDR make several recommendations to improve the quality of the soil gas and ambient air monitoring.


PUBLIC HEALTH RECOMMENDATIONS AND ACTIONS

The Public Health Recommendations and Actions Plan (PHRAP) for this site contain a description of actions taken, to be taken, or under consideration by ATSDR and CDHS at and near the site. The purpose of the PHRAP is to ensure that this health consultation not only identifies public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The CDHS and ATSDR will follow-up on this plan to ensure that actions are carried out.

Actions Completed

  1. CDHS responded to the LAUSD's request for assistance in regards to the Park Avenue School.

Ongoing Actions

  1. CDHS is participating in a workgroup put together by LAUSD to oversee the environmental safety and health issues at existing and proposed schools.

Recommendations for Future Action

  1. Conduct chemical analyses with low enough detection limits to measure chemicals at levels of concern corresponding to a 1x10-6 cancer risk if breathed for a lifetime. (LAUSD)


  2. Conduct air sampling on a regular basis at an upwind location, such that the contribution of upwind sources, particularly for PCE, can be assessed. (LAUSD)


  3. Conduct air monitoring on a regular enough basis to establish a more clear trend in the data. (LAUSD)


  4. Provide air monitoring information in an easy to understand format available for interested parents. (LAUSD)


  5. Request CDHS review of the data, if a different trend of contaminant concentrations are indicated by the future monitoring. (LAUSD)

PREPARERS OF REPORT

Environmental and Health Effects Assessor:

Marilyn C. Underwood, Ph.D.
Staff Toxicologist
Environmental Health Investigation Branch
California Department of Health Services

ATSDR Regional Representatives:

William Nelson
Gwendolyn Eng
Dan Strausbaugh
Regional Representatives, Region IX
Agency for Toxic Substances and Disease Registry

ATSDR Technical Project Officer:

Tammie McRae. M.S.
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch, State Programs Section


REFERENCES

  1. California Air Resources Board Monitoring Program, Samples collected at 1630 North Main Street in Los Angeles from 1990-1996. At http://arbis.arb.ca.gov.

CERTIFICATION

This Park Avenue School Health Consultation was 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 health consultation was begun.


Tammie McRae, M.S.
Technical Project Officer
Superfund Site Assessment Branch (SSAB)
Division of Health Assessment and Consultation (DHAC)
ATSDR

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


Lisa C. Hayes
for Richard E. Gillig, M.C.P.
Chief, SPS, SSAB, DHAC, ATSDR


APPENDIX

Table 1.

Summary of Maximum Concentrations Measured in air, soil gas, and vents at Park Avenue School
  Upgradient Ambient Air< North Vent South Vent Center Vent Vadose #2 Vadose #4 Vadose #5 Vadose #11 Vadose #15 Typical Urban LA Air
Dichlorofluromethane 9.1 11.5 6.2 6.8/32.2 6.8 6.2 3.8 5.8 29.5 254.5 NA
1,1,1,-trichloroethane (TCA) 30.2 14.6 10.2 9.15 10.4 32/240 10.4/1500 23.8/540 13.1/340 31.9/1400 10
Benzene 13.2/30 4.96 2.3/30 3.7 2.8 5.3 8.7 4.96 4.34 4.34 7.4
Toluene 9.3/97 16.1 140/1266 189/1803 167/3642 16.9 14.7 14.7 7.9 11.2 51
Xylenes 3.7/140 6.6/27.5 122/170 10.5/90.6 26.1/230 45.2 33.8 33.8 15.8 21.1 9.7
Methy ethyl ketone 106 Not detected (ND,<90) ND(<90) 136 ND(<90) 136.5 ND(<90) 217.5 241.2 ND(<90) 3.0
Methylene chloride 4.4 34.1 20.5 17 6.1 40.4 117.2 14.7 13.4 19.7 22
Tetrachloroethylene (PCE) 2.3* 10 15 3.7 3.4/6.7 11 3.6 5.1 7* 6.2* 2.8
1,1,2-TCA ND 2.6* ND 2.7* 2.8* 3.4 11* 34* ND ND NA
Carbon tetrachloride 2.4* 2.4 29.2/77.1 2.25 2.25 2.7 2.85 2.7 2.7 1.95 0.18
Trichloroethylene (TCE) ND 0.3 0.9* ND 6.2 0.3* ND ND ND ND 8.7
1,1- Dichloroethylene (1,1-DCE) ND ND ND 9.3* ND ND 6* 110* ND 5* NAM
Maximum concentrations are shown in parts per billion (ppb); if this was an outlier maximum concentration then the second highest concentration is also listed.
* Indicates that the maximum concentration is the only detection off this chemical.


DEPARTMENT OF HEALTH SERVICESDEPARTMENT OF HEALTH SERVICES
1515 CLAY STREET, SUITE 1700
OAKLAND, CA 94612
(510) 622-4500

March 8, 2000

David Jensen, P.E.
Camp Dresser & McKee Inc.
18881 Von Karman Avenue, Suite 650
Irvine, CA 92612

Dear Mr. Jensen:

The California Department of Health Services Environmental Health Investigations Branch (CDHS-EHIB) reviewed soil gas and ambient air data collected at the Park Avenue Elementary School at your request on behalf of the Los Angeles Union School District (LAUSD). This request is part of LAUSD's response to parents' concerns about bubbling that occurs on the asphalt covered playground during the summer months. We reviewed the large data package that was sent to us after speaking with Gary Pons of your staff. Prior to receiving this information, CDHS-EHIB had no prior involvement with Park Avenue School, and had not reviewed any other documents related to the contaminated soil that was removed from the school property. Staff who reviewed the material work on a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR).

The Park Avenue School was built in 1968. Starting in 1968 until cleanup occurred in 1990, a black-tar like substance would surface and pool on asphalt-paved areas of the school yard during hot summer months. An investigation into the origin of the material by LAUSD determined that the Vloedeman Dump/B.H. Steepleton Landfill had operated at, and adjacent to, the school yard from the 1920's to the 1950's. Apparently, these landfills received refuse and petroleum wastes. Petroleum wastes were deposited in two large sumps located on and near the school property. LAUSD conducted an investigation of the tar-like substance and the extent of contamination. The contamination consisted of polynuclear aromatic hydrocarbons (PAHs), benzene, other volatile organic compounds, and lead. In 1990, LAUSD removed 2,400 cubic yards of petroleum contaminated soil from the bungalow and parking lot areas (southern border of the property). A passive vent system consisting of a series of perforated pipes was buried 10 feet below the surface of the turf area and the playground area, with three vent stacks located at the western edge of the property. The vent stacks release the untreated soil gas from a 4" pipe approximately 10 feet above ground. The playground and turf areas are capped with a cover to prevent contact with the subsurface soil.

Since the cleanup was completed, LAUSD has conducted soil vapor sampling from five vadose zone wells located throughout the school property (essentially soil borings that capture the soil gas from1-2 foot below the surface), the vent system, and ambient air. The samples are typically analyzed for volatile organic compounds including aromatic hydrocarbons.

The following is a summary of air monitoring data sent to CDHS for review. We have grouped the data on the basis of the laboratory and/or methods that were used.

  1. Samples included ambient grab, upgradient air grab, ambient eight hour, upgradient eight hour, vent-south, vent-north, vent-middle, vadose zone wells #2, #4, #5, #11 and #15 collected on 10/16/90, 11/19/90, 12/19/90, 1/15/91, 2/12/91, 3/21/91, 4/16/91, 5/14/91, 10/15/91, and 1/15/92. Sixteen VOCs including methane were analyzed. Low levels of 1,1,1-trichloroethane, benzene, toluene, and total xylenes were consistently detected. Occasional hits of low levels of methyl ethylketone, methylene chloride, methane and dichlorofluoromethane were detected in all of the samples. We reviewed these samples to get an understanding of the historical exposure levels. Since upgradient air samples as well as ambient air samples on-site were collected, we also used this data to assess the influence that the former landfill may have on the schoolyard air.


  2. Samples included ambient grab, upgradient air grab, ambient eight-hour, upgradient eight hour, vent-center, vent-north, vent south, vadose zone wells 2, 4, 5, 11 and 15 collected on 4/29/92, 7/29/92, 10/30/92, 2/10/93, 5/27/93, 9/22/93, 4/7/94, 11/7/94, 2/23/95, and 5/6/96. (Ambient eight hour and upgradient eight hour were not collected on 11/7/94, 1/24/96, and 5/6/96.) These samples were analyzed using EPA method 601 (30 halogenated VOCs) and EPA method 602 (benzene, toluene, ethylbenzene, and xylenes). Except for 5/6/96, nothing was detected in any of the samples, due to extremely high detection limits. The detection limits were considerably lower for the samples collected on 5/6/96 and low levels of dichlorofluoromethane, chloromethane, trichlorofluoromethane, 1,1,1-TCA, carbon tetrachloride were detected in all the samples. The field/trip blank also contained these chemicals at about 1/10 the level found in the site samples. Because of the elevated detection limits, only the 5/6/96 data was used in this review.


  3. Samples were collected from vadose zone wells #2, #4, #5, #11, and #15 on 1/16/97 and 7/23/97. The samples were analyzed for "gas phase volatile compounds" of a suite of approximately 45 VOCs. No compounds were detected in the samples collected on 1/16/97 due to extremely high detection limits. 2-Butanone, 1,1-dichloroethylene, and 1,1,1-TCA were measured in the samples collected on 7/23/97.


  4. Samples were collected from ambient grab, vent-south, vent-center, vent-north, and vadose zone wells #2, #4, #5, #11, and #15 collected on 6/23/99 and 1/27/00. These samples were analyzed using EPA method 8260B (also called SCAQMD method TO-14) for a suite of 38 VOCs. These analyses had adequate detection limits, and several chemicals were detected in all the samples. These analyses will be used to evaluate the health concerns related to the site.

Review of historical data (1990 & 1991)

The early soil gas/air monitoring included both an ambient and upgradient grab sample and eight-hour sample collections. The upwind sample was reportedly collected to the northwest of the site. The upwind and on-school samples had very similar levels of dichlorofluoromethane, 1,1,1-TCA, benzene, toluene, and xylenes. This seems to indicate that the soil gas is not affecting the air quality on the school property. In addition, the levels of these chemicals are typical for urban air. During this time period, low levels of dichlorodifluoromethane, 1,1,1-TCA, benzene, toluene, and xylenes, were present in the air collected from the vents. Since these gases are released at the property line, soil gas probably has had little, if any, effect on the air quality in the school property. This is most likely due to the placement of the soil gas vents on the east side of the school property such that the wind blowing predominantly west to east would disperse the soil gas from the vents away from the school property. During this same time period, low levels of dichlorodifluoromethane, 1,1,1-TCA, benzene, toluene, methyl ethyl ketone, methylene chloride, toluene, and xylenes were detected in the air collected from the vadose wells. However, the air sampling indicates the cap/asphalt cover appears to be doing an adequate job at preventing the soil gas from migrating out from underneath the cap/asphalt cover and affecting the air quality.

Review of more recent data (1996-2000)

Most of sampling events since May 1996, included analyses for a large number of chemicals and had appropriately low enough detection limits. This allowed for a better understanding of the variety and levels of chemicals in the soil gas and ambient air. However, because no upgradient ambient air was collected, it is difficult to make a clear statement about the impact of the soil gas on the ambient air on the school property. The ambient air collected on the school property during this time period contained several VOCs that are typically found in outdoor air. The levels measured on the school property are generally within the range of typical Los Angeles air; thus seeming to indicate that the ambient air is not unusually influenced by the possible residual contamination. The tetrachloroethylene levels from the samples collected on 1/27/00 and 6/23/99 appear to be greater than one would expect for typical Los Angeles air. Interestingly, PCE was not detected (with low detection limits) in the outdoor air in the 90/91 monitoring. Since this observation is based on only two recent samples, the importance of this should be followed over the next few years. Though there is PCE in the soil gas, the levels in the soil gas would not seemingly provide a large enough source for the amount of PCE measured in the ambient air. It may be important to again conduct an upgradient ambient air sampling as was done in the past. This might help to determine if there is an upwind source of the PCE.

Health concerns of the ambient air and soil gas.

There are no regulatory standards or guidelines for volatile compounds in the subsurface soil zone that relate to breathing zone levels. Therefore, in order to evaluate the data, we assumed a worst-case scenario, that the constituents / concentrations of chemicals in the vent stacks are being breathed by someone. Assuming someone is breathing the vent gas is akin to someone sitting next to a hypothetical break in the cap and breathing the gases coming up through that hole. This, in a sense, is similar to the possible scenario that the community is concerned about, which is the release of vapors through the cap and into the surrounding air.

The chemicals detected in the ambient air and the three vents in sampling collection data 6/23/99 and 1/27/2000 were evaluated for non-cancer health impact. Several of the chemicals detected in the ambient air and soil gas are considered to be carcinogenic. Thus these chemicals were also evaluated for their possible carcinogenic effects (see below). None of the levels of the chemicals measured in the ambient air or vented soil gas exceed the non-cancer health comparison values (USEPA's Reference Concentration (RFC), or ATSDR's Minimal Risk Level (MRL)). The RFC or MRL is defined as an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups like children) that is likely to be without appreciable risk of deleterious non-cancer health effects during a lifetime. Thus, the chemicals present in the air or the soil gas vent stacks would not be expected to cause non-cancer health effects.

Several of the chemicals detected in the ambient air and soil gas are considered to be carcinogenic based on human and animal studies. The total cancer risk for a lifetime of breathing the low levels of 1,1,-DCE, benzene, carbon tetrachloride, trichloroethylene, 1,1,2-trichloroethane, and tetrachloroethylene ranged between 9 to 15 in 10,000. This is considered a low cancer risk. This is very comparable to the cancer risk that the South Coast Air Quality Management District estimated for typical Los Angeles Air. Thus, the ambient air and soil gas poses a cancer risk that is similar for the Los Angeles air.

Conclusion and Recommendations.

The ambient air at the Park Avenue School seems to be relatively unaffected by any residual contamination in the soil on-site. The ambient air and soil gas would not be expected to result in non-cancer health effects. The ambient air and soil gas poses a low increased cancer risk, similar to the risk posed by typical Los Angeles urban air.

These conclusions could be stated with more confidence if better air monitoring had been conducted in the past. The following recommendations will assist with a future evaluation:

  • Conduct chemical analyses with low enough detection limits to measure chemicals at levels of concern corresponding to a 1x10-6 cancer risk if breathed for a lifetime.


  • Regularly conduct air sampling at an upwind location, such that the contribution of upwind sources, particularly for PCE, can be assessed.


  • Conduct air monitoring on a regular enough basis to establish a more clear trend in the data.


  • Provide air monitoring information in an easy to understand format available for interested parents.


  • Request our review of the data, if a different trend of contaminant concentrations are indicated by the future monitoring.


  • If we can be of further assistance, please contact Marilyn C. Underwood, Ph.D. at 510 622-44415.

Sincerely,



Marilyn C. Underwood, Ph.D.
Staff Toxicologist
Environmental Health Investigations Branch


Richard A. Kreutzer, M.D.
Chief
Environmental Health Investigations Branch

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