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To decide whether nearby residents, base tenants, and workers are exposed to contaminants migrating from the site, ATSDR evaluates the environmental and human components that lead to human exposure. This pathway analysis consists of five elements: a source of contamination, transport through an environmental medium, a point of exposure, a route of human exposure, and an exposed person or population.

If an exposure pathway cannot be eliminated, ATSDR categorizes it as a completed pathway or potential pathway. Completed pathways require that the five pathway elements exist and show that exposure to a contaminant occurred in the past, is occurring, or will occur in the future. Pathways are considered potential when one of the five elements is missing, but could exist. Potential pathways show that exposure to a contaminant could have occurred in the past, could be occurring now, or could occur in the future. Table 15 identifies the completed exposure pathways; Table 16 identifies the potential exposure pathways. Table 17 shows the estimated number of exposed persons for completed and potential exposure pathways. The discussion that follows includes only those pathways that are important and relevant to the site.

A. Completed Exposure Pathways

Industrial Landfill (IR-1/21) and Bay Fill Area (IR-2)

People were exposed to contaminants disposed of at the Industrial Landfill and the Bay Fill Area. Wastes disposed of include 21,000 gallons of liquid chemical waste, 500 cubic yards of asbestos, domestic wastes and refuse, building construction and demolition wastes, dredge spoil materials, sandblast wastes, shop industrial and chemical and solvent wastes, and low-level radioactive wastes (2, 16). Contaminants of concern in soil include antimony, arsenic, cadmium, manganese, nickel, vanadium, copper, lead, PCBs, and PAHs. Exposed populations include landfill operators; Navy personnel and dependents who used the shoreline/wetlands area near the BEQ; base tenants; and recreational users of the shoreline area (e.g., Navy personnel who stayed at the BEQ). Table 18 (Public Health Implications section) lists how they were exposed.

The landfill operator's soil ingestion rates were likely higher than other identified populations because of their work-related activities. Conditions at landfills are often dry and dusty as workers use heavy equipment to dig holes, bury, and compact the wastes. The equipment used during the 1950s generally did not have doors or windows. Additionally, workers were probably not required to wash their hands before breaks and would likely ingest more dust through hand-to-mouth activities. All of those factors would result in a higher than normal soil ingestion rate.

The Industrial Landfill and the Bay Fill Area are within a partially fenced area. Fencing was installed in 1991 along the land access points. However, there is neither fencing along the shoreline nor signs posted warning of radiological or environmental hazards. The Navy is in the process of installing signs along IR-1/21 and IR-2. Access to those areas could be gained by boat or by foot at places along the fence line that are not well patrolled.

On-Site Radioactivity in Soil

Past completed exposures through ingestion, inhalation, dermal contact, and irradiation of contaminated soil were identified at Industrial Landfill, Bay Fill Area, the Officers Club, the Oily Liquid Waste Disposal Area, the Oily Waste Pond and Incineration Tank, and the Sub-Base Area. Exposures at IR-1/21 and IR-2 likely occurred because the surface is unpaved and exposed radium sources were found. A number of those sources were likely crushed during landfill operations thus releasing Ra-226 into the environment. Ra-226 was detected in the soil and in the intertidal zone in a 600 x 600 foot area at IR-2 (Figure B-6). In the past, populations exposed include landfill operators; Navy personnel and dependents who used the shoreline/wetlands area near the BEQ; base tenants; and recreational users of the shoreline area (e.g., Navy personnel who stayed at the BEQ).

The identified exposed populations were exposed to ionizing radiation from Ra-226 by nearness to contaminated point sources at IR-1 and IR-2, direct contact with soils or slag materials, incidental ingestion, and inhalation of soil particles. The radioactivity of the point sources found at HPA differed greatly. External exposure depends on proximity (for HPA a matter of feet) and strength of HPA Ra-226 point sources.

Remediation of IR-1/21 and IR-2 is being discussed between state and federal regulatory agencies and the Navy (18, 21). ATSDR will review the radiation remediation workplans to ensure that base tenants and the public will not be adversely impacted by the remediation. The potential health impact of past exposures to Ra-226 will be discussed in the Public Health Implication section.

B. Potential Exposure Pathways

On-Site Ambient Air

The Navy conducted an initial screening air monitoring study based on a one time sampling event (62). That study was designed to evaluate the presence of elevated levels at the facility and to provide data that could be used in combination with dispersion modeling for the public health and environmental evaluations to be conducted at HPA. The study provided limited information on how people may be exposed to air-borne contaminants. More sampling is planned. Pesticides (heptachlor, lindane, aldrin, dieldrin, endrin, and DDT) were detected at the northwest and southeast ends of the base at air monitoring stations 8 and 11. Figure B-8 shows the locations of the air monitoring stations and the proposed locations of future air monitoring stations. The potentially exposed populations are downwind from the northwest station where the higher pesticide concentrations were detected. Wind rose data from the San Francisco International Airport, which is approximately 8 miles south of HPA, indicate that the prevailing wind direction is from the west-northwest. The Navy conducted a Solid Waste Air Quality Assessment Test (SWAQAT) between October 7-14, 1988 which also indicated that the predominant wind direction is from the west-northwest. Prevailing winds would transport emissions and airborne particles predominately to the east-southeast out across the base toward the bay (24, 62).

Base personnel, on-site tenants, remediation workers, construction workers, and future HPA residents may have or could inhale ambient air contaminated with pesticides; the source is unknown. In addition, people may incidentally inhale and ingest contaminated OU III surface soil particles. Metals and Aroclor-1260 were detected above comparison values in OU III surface soils. Base personnel and on-site tenants may be exposed during activities such as walking or jogging around the base. The San Francisco Police Athletic Club, one of the base tenants, reportedly has members who jog on base. Other possible exposure activities are eating lunch or smoking outdoors. In addition, exposure may occur to employees in the wood-chipping business which is adjacent to the landfill, outside of the western base boundary. Table 16 outlines the ambient air pathway. Base personnel and on-site tenants may be chronically exposed (longer than one year) to contaminants in the ambient air as often as five to six times a week.

An additional future exposure pathway may also exist for base personnel, on-site tenants, remediation workers, construction workers and future HPA residents who may be exposed to airborne contaminants released when subsurface soil is excavated or disturbed during construction, or future land reuse. On February 4, 1988, four public utility workers complained of skin rashes and itching after entering manholes near Drydock 4 (83). Prior to entering the manholes, the public utility workers "pumped and blower vented" the manholes for approximately 15-30 minutes and checked for various gases. As a result of this incident, the Navy recommended several additional safety measures for public utility workers (84). The available information is incomplete; the cause of these symptoms is unknown. Dermal absorption or contact dermatitis are the suspected routes of exposure. The exposure duration was short-term and the symptoms disappeared within 24 hours.

On-Site Indoor Air Pathway

People may potentially be exposed to contaminants from past waste generating activities in the HPA buildings. Appendix D lists the past and known current uses of PA areas. Base tenants and workers may be exposed by inhaling indoor contaminants or touching potentially contaminated surfaces. Those exposures may be long term. ATSDR has a listing of the buildings that are being leased, but does not have the number of people that are renting or working in individual HPA buildings or what their activities are. Adequate indoor air monitoring information is unavailable at this time to fully assess this pathway. Table 16 outlines the indoor air pathway.

On-Site Surface Soil

Tenants at Building 364 (PA-33), Building 418 (PA-33), Building 366 (PA-34), Building 704 (PA-36), Building 406 (PA-36), Building 405 (PA-36), Building 401 (PA-37), Building 435 (PA-37), Building 436 (PA-37) maybe exposed to contaminants in surface soil. The Navy conducted sampling at Parcel D in 1993 and detected VOCs, SVOCs, PCBs, pesticides in surface soil outside of the above mentioned buildings. Additional sampling is planned for Parcel D (32). Exposures depend upon the tenants activities outside of the buildings they are leasing. Activities such at smoking or eating lunch outdoors may lead to exposure.

Off-Site Surface Soil

People living near or working along the railroad right-of-way (PA-52) may be exposed to contaminants in surface soil by way of ingestion. PA-52 extends off site into the neighborhood west of Parcel E (Figure 2). The contaminants of concern are PCBS and lead. The Navy recommends that the right-of-way be capped with asphalt or other appropriate material or surface soil should be removed to reduce the potential for exposure to contaminated soil (25).

Surface Water and Sediment

People may have been or could come in contact with radiation contaminated surface water and sediment from IR-2 and at areas in the bay that receive contaminated surface water and sediment runoff from the other contaminated areas on site. Access to IR-2 could be gained by boat along the shore or at places along the fence line that are not well secured. Trespassers or future land users who swim or play along the bay at IR-2 may be exposed to radiation contamination through skin absorption and accidental ingestion of contaminated surface water and sediment. The estimated exposure duration would be short term, occurring less than 14 days per year.

Food Chain

Past, present, and future food chain pathways potentially exist for people who ingest fish and shellfish. A potential exposure pathway exists for people who may eat shellfish that have been in direct contact with radioactive point sources in the IR-2 intertidal zone of the bay. The Navy has conducted limited shellfish tissue analyses. The radiological analysis of mussel tissues has not been submitted. ATSDR cannot thoroughly evaluate the food chain pathway until further toxicological and chemical tests and radiological surveys have been conducted. Furthermore, surface soil sampling may be needed to identify if runoff from the landfill is contributing to contamination of sediment and possibly fish and shellfish.

The food chain is the series of organisms that are consumed by each other, beginning from single-celled animals and increasing in size to multi-celled animals and then to man, the highest trophic or predator level. Chemicals in the environment can be passed through the food chain to man. Bioaccumulation is the uptake of a chemical from water or food by an organism. Bioconcentration is the process by which tissue concentrations of a bioaccumulated chemical increase as the chemical passes from one food chain or trophic level to a higher level by way of ingestion of various organisms. Contaminants appear to be bioaccumulating in food chain entities at HPA.

Several edible fish species including striped bass, sturgeon, sand shark, herring, flounder, perch, and bullhead may be or become contaminated from sources on site (33). PCBs, metals, and pesticides were detected in HPA sediment and storm water samples. Those contaminants are known to bioaccumulated in fish and shellfish. Fishing including subsistence fishing, occurs year round near HPA. Seasonal fishing for game fish takes place during the months of May through August and from December through February. The extent of any shellfishing is unknown.

The waters of the San Francisco Bay are subject to high winds and strong tides and currents. Further, depth of the bay varies greatly. Consequently, environmental contaminants in the bay from various sources have been greatly mixed and distinguishing their sources is difficult. However, the degree of mixing in basins and inlets is less (e.g., in the basin area north of Candlestick Park). Therefore, contaminant levels in these closed areas would be expected to be higher than in other areas of the open bay and the source of contamination can be more readily identified.

People may be exposed to contaminants in fish and shellfish who would be considered at special risk. Specifically people such as Asians (about 14% of the Hunters Point/Bayview area), whose fish and shellfish ingestion rates are greater (60-138 grams/day) and more frequent (more than once a day) (72) may be at greater risk. There are community wide concerns about the impoverished Asian immigrants who engage in subsistence fishing in the San Francisco Bay (85). Other Hunters Point/Bayview area populations who subsistence fish include blacks, Native Americans, Pacific Islanders, and Eskimos. Many of the area minority groups and immigrants are unaware of the risks of eating contaminated fish and shellfish (86). Table C-4 gives the demographic breakdown for those populations. Available information also shows that those potential exposures may be short or long term depending on the population's fishing practices and fish-consumption rates.

There is a bay wide fishing advisory for striped bass due to high mercury levels; the source is unknown. The California Department of Fish and Game has suggested that because of elevated mercury levels, no one should eat more than four meals per month of striped bass from the San Francisco Bay Delta region. Women who are pregnant or may soon become pregnant, nursing mothers, and children under age six should not eat any striped bass from the area (47). The RWCQB has advised against placing a commercial herring hatchery off the HPA coast (87). In addition, the state has issued fish and shellfish advisories for PCBs (67).


Workers on site (for example remediation, construction, and utility workers) and people using buildings along the base boundary, and future base residents may be in danger from methane buildup and explosion in or near IR-1/21 and IR-18. In addition, methane may be migrating from the northern part of the Industrial Landfill. Methane presents two threats to people explosion and that of asphyxiation.

Methane gas was detected in 7 samples at concentrations ranging from 0.5 to 83 percent. Figure 4 shows the explosiveness range for methane. The amount of methane produced during the bacterial decomposition of organic materials exceeds the explosive range; however, as the gas migrates, it is almost always diluted by air to combustible or explosive proportions (88). When uncontrolled, landfill gas can migrate subterraneously as far as 1,000 feet. This presents a problem, not only because of the explosive hazard, but also because the carbon dioxide and methane mixture present can displace air in enclosed areas (basements, manholes, etc.) and asphyxiate people.

Anaerobic decomposition of buried refuse and petroleum products is the probable source of methane at the Industrial Landfill, the Bay Fill Area, the Disposal Trench Area, the Waste Oil Disposal Site, the Oil Reclamation Pond and the Sub-Base Area. Because the landfill contains organic compounds, methane can be produced for long periods of time (e.g., up to 50 years). Therefore, abandoned and forgotten landfills may still be actively producing methane. The Navy used Industrial Landfill from 1958 to 1974 (88).

The likely movement of the IR-1/21 methane plume movement would be north to west. Two processes, convection and diffusion affect the direction of plume movement. Convection, the movement in response to pressure gradients which may move the gas laterally from the landfill through pathways of least resistance (opposite of the groundwater flow which is towards to bay). The other process which influences gas movement is diffusion, the movement from areas of higher concentrations to areas of lower concentration. Water conduits, a steel drain culvert, and buried utility lines running near landfills all provide corridors for methane migration (88).

The EPA criteria for municipal landfills states that owners must ensure that the concentration of methane gas does not exceed the lower explosive limit (5%) for methane at the facility property boundary (90). ATSDR is not aware of any routine methane monitoring taking place at HPA except during drilling. Presently all but one of the methane pockets are located within Parcel E which is a fenced area and there are no people or installation buildings nearby. However, there are several buildings along the HPA boundary (Figure 15), within a few hundred feet of the IR-1/21 plume. Although future use of this area has not been determined, building or drilling in these areas may present a physical hazard to future land users if the extent of the methane present is not more completely mapped out.

Although the Navy follows site safety plans, uses gas monitoring equipment (e.g., organic vapor analyzers, oxygen meters, and explosimeters) and equipment certified (e.g., non-sparking) for use in an explosive atmosphere when drilling in IR-1/21 and other areas where methane has been detected, an explosion hazard still exists for drillers during installation of monitoring wells and when boring for soil samples. During a site visit, in an area to the east of the road intersecting IR-1/21, ATSDR representatives observed workmen attempting to install monitoring wells. Well drilling had to be discontinued because methane gas was released. Therefore, even though the Navy takes precautions periodically levels are still a problem for well drillers.

Workers, people using buildings along the base boundary, and future base residents may be in danger from methane buildup and explosion in or near IR-1/21, IR-2, IR-3, IR-12, IR-18, and IR-7.

C. Eliminated Pathway

Off-Site Groundwater

Contaminated groundwater pose no apparent risk to private well users. Two plumes have been identified and found to be migrating northeast from IR-6 and IR-10. Contaminants detected at IR-6 and IR-10 include VOCs, PAHs, and metals. The Hunters Point/Bayview area is topographically upgradient of HPA. The wells may be used by nearby laundries, schools, and businesses for unknown purposes; the Navy conducted a limited well survey of the Hunters Point/Bayview area and identified seven wells. However, the possibility of contaminated groundwater reaching privately owned wells is highly unlikely. Groundwater flow is towards the bay.

D. Summary of Pathways Analysis

The landfill soil pathway is complete because exposure to metals, PAHs, PCBs, and Ra-226 via ingestion, inhalation, and irradiation has occurred. The people exposed include landfill workers, military, civilian, and tenant populations including trespassers using or working at areas that have radiation contamination. Landfill workers would have had the greatest exposure.

The potential exposure pathways include ambient air, surface soil, indoor air, fish and shellfish caught at or near HPA, and physical hazards. In addition, people could be exposed to contaminants in surface water and sediments. Tables 15 and 16 outline the exposure pathways.

When land use changes and if area contaminants are not remediated, people may be exposed to contaminants present site wide. During remediation or future land reuse, construction and utility workers (e.g., those installing fencing, utilities, etc.) and future HPA occupants could be exposed to contaminants found on base.

Table 15. Completed Exposure Pathways
On-Site Soil PAHs, PCBs, and Metals Industrial Landfill and Bay Fill Area Soil Surface Soil Incidental Ingestion of Soil People who used the BEQ shoreline/wetlands area

Landfill workers

Base residents who walked in landfill/bay fill areas


Future land users

Future exposures dependent on future land use
On-Site Radiation - Soil Ra-226 Industrial Landfill and Bay Fill Area Soil Crushed and disintegrated radium sources Incidental Ingestion and inhalation of Ra-226 and external exposure to gamma radiation People who used the BEQ shoreline/wetlands area

Landfill workers

Base residents who walked in landfill/bay fill areas


Future land users

Partial fencing installed in 1991

Navy operated landfill from 1958 to 1974

BEQ located on IR-2 used during 1980s

Table 16. Potential Exposure Pathways
Food Chain PCBs, PAHs, Metals, and Ra-226 Contaminated Storm Water, Storm Water Run-off, Storm Water Sediments, and Bay Sediments from base areas and Ra-226 at IR-2 Food Chain Contaminated Shellfish and Fish Ingestion Persons eating fish or shellfish caught off or near HPA Past
No fish tissue sampling and little shellfish sampling data are available. ESAP data package incomplete
Off-Site Surface Soil Metals and PCBs Contaminated Surface Soil Surface Soil Contaminated Soil Incidental Ingestion Persons living near the railroad right-of-way Past
The railroad right-of-way extends of base into the Hunters Point/Bayview area.
Off-Site Sediment and Surface Water PCBs, PAHs, Metals, and Ra-226 Contaminated Storm Water, Storm Water Run-off, Storm Water Sediments, and bay Sediments from Base sites and Ra-226 at
Sediment and surface water Contaminated water and Sediment Incidental Ingestion, inhalation, and dermal contact Persons engaging in recreational activities Past
No off-site sampling has been conducted

Little, if any, swimming takes place near HPA.

On-Site Air Pesticides and Metals Unknown Air Base Ambient Air Inhalation People leasing sites, working or jogging on site Past Present
Only a screening air study has been conducted. Base tenants and workers are likely to come in contact with airborne pesticides. The source of the pesticide contamination is unknown.
Metals and PCBs OU III Surface Soils Inhalation and Ingestion Present
Indoor Air Unknown Past activities at PA areas Air and Surfaces PA areas Inhalation and Direct Contact Base tenants using PA areas Present
PA area sampling has not been completed and does not include indoor air sampling. ATSDR does not have list of tenant activities.
Physical/Explosive Methane Past landfill activities Sub-surface soil and indoor air IR-1, IR-2, IR-3, IR-18, IR-7, and IR-12 Explosive hazard (physical) Remediation and construction workers drilling at methane areas or base tenants leasing buildings near IR-1 and IR-12 Present
Many methane pockets have been defined by the Navy and may present a physical hazard from explosions when drilling, excavating, or performing subsurface sampling at methane areas. Methane gas may migrate into confined spaces or basements if buildings are built on areas such as IR-1/21 or IR-12.

Table 17. Estimated Exposed Populations
Exposed Population/Location Pathway Estimated Persons Chemical by Exposure Media
VOC SVOC Metals PCBs and Pesticides PAH Physical Radiation
Landfill operators, BEQ residents and base residents that visited the Bay Fill and Industrial Landfill Areas, base tenants, and trespassers Completed unknown

Soil Soil Soil
General public that fishes near HPA Potential 50 per week

Shellfish and Fish

Shellfish and fish
General public that comes in contact with off-site sediments and surface water near HPA Potential unknown Sediments and Surface Water Sediments and Surface Water Sediments and Surface Water Sediments and Surface Water Sediments and Surface Water
Sediments and Surface Water
Base tenants leasing PA areas Potential <200 Air Air Air and Surfaces Air and Surfaces Air and Surfaces Indoor Air Contaminated surfaces
Remediation workers Potential <50

Base tenants and base personnel who work and/or jog and contractors in the southern half of the base Potential <100

Air Air

Trespassers on IR-1/21 and IR-2 Potential unknown

Soil Soil Soil
Soil and Sediment


In this section, ATSDR discusses health effects that may result from exposures to site contaminants. Chemicals released into the environment do not always result in human exposure. People can only be exposed to a site contaminant if they breathe, ingest, or touch the contaminant. In addition, if radioactive materials are present, exposure can also occur by being near contaminated water, soil, or air (irradiation).

Factors that influence exposure include the exposure concentration (how much), the duration of exposure (how long), the route of exposure (breathing, eating, drinking, or skin contact), and the multiplicity of exposure (combination of contaminants). Once a person is exposed, individual characteristics -- age, sex, nutritional and health status, lifestyle, and family traits -- influence how the contaminant is absorbed (taken up by the body); metabolized (broken down by the body); and excreted (eliminated from the body). When the contaminant is a radionuclide, the same factors and individual characteristics apply along with exposure via external irradiation in determining the health effects.

ATSDR considers the above physical and biological characteristics when developing health assessment guidelines. Toxicological profiles prepared by ATSDR summarize chemical specific toxicological and adverse health effects information. Health assessment guidelines such as ATSDR's Minimal Risk Level (MRL) and EPA's Reference Dose (RfD) and Cancer Slope Factor (CSF) are included in the toxicological profiles. Those health assessment guidelines are used by ATSDR health professionals in determining the potential for developing adverse non-carcinogenic health effects and/or cancer from exposure to a hazardous substance.

A Minimal Risk Level (MRL) provides a basis for comparison with concentrations of contaminants in different environmental medium (soil, air, water, and food) to which people might be exposed. If daily exposure occurs at an amount below the MRL, harmful noncancerous health effects are not expected to occur. The method for deriving MRLs does not include information about cancer, therefore, an MRL does not imply anything about the presence, absence, or level of cancer risk.

An EPA Reference Dose is an estimate of the daily exposure for the human population, including sensitive subpopulations, that is likely to be without appreciable risk of adverse non-carcinogenic health effects during a lifetime (70 years). The RfD is a health guideline for the oral route of exposure. For carcinogenic substances, EPA has established the Cancer Slope Factor (CSF) as a health guideline. The CSF is used to determine the number of excess cancers expected from exposure to a contaminant. CSF is not calculated for children. Scientific information is incomplete as to the level of cancer risk in children. Cancer risk research is based on an adult exposure of 70 years.

Using the available health guidelines and scientific information, ATSDR determines the likelihood that an adverse health effect, cancerous and/or noncancerous, will occur as a result of exposure to contamination. Cancerous and noncancerous health effects occur via different biological mechanisms, and therefore, are evaluated separately using different health guidelines and scientific information. If either cancerous or noncancerous health outcomes are expected to occur as a result of exposure to contaminants, the exposure is determined to be of public health concern.

To link the site's human exposure potential with health effects that may occur under site-specific conditions, ATSDR estimates human exposure to the site contaminant from ingestion and/or inhalation of different environmental media. The following relationship is used to determine the estimated exposure to the site contaminant:

    ED = (C x IR x EF) / BW
    ED = exposure dose (mg/kg/day)
    C = contaminant concentration
    IR = intake rate
    EF = exposure factor
    BW = body weight

ATSDR uses standard intake rates for ingestion of soil. For incidental ingestion of soil, the intake rate is 500 mg/day for the landfill operator's occupational exposure, 100 mg/day for adults, 200 mg/day for children, and 5000 mg/day for children with pica behavior (repeated ingestion of non-nutritive substances). Standard body weights for adults and children are 70 kg and 16 kg, respectively. Generally, the maximum contaminant concentration detected at a site for a specific medium is used to determine the estimated exposure. For this health assessment, ATSDR used a mean concentration to calculate the exposure dose. Use of the maximum concentration detected in a specific medium will result in the most protective evaluation for human health. In addition, some exposures occur on an intermittent or irregular basis. For those exposures, an exposure factor (EF) is calculated that averages the dose over the exposure period.

A. Toxicological Evaluation

The following sections evaluate the potential health effects of people who were exposed to contaminants at HPA. The toxicologic evaluation of each contaminant assesses probable health effects associated with exposure to the contaminant. The health effects are related to contaminant concentration, exposure route, exposure frequency, duration, and population exposed. Populations known or suspected to be sensitive to the contaminant are included in the evaluation. People were exposed to site contaminants at the Industrial Landfill and the Bay Fill Area. Those exposures and the public health implications associated with them will be discussed here.

Industrial Landfill (IR-1/21) and Bay Fill Area (IR-2)

In the past, people were exposed to PCBs, PAHs, and lead at both Industrial Landfill and the Bay Fill Area. At the exposure levels, we estimated that cancerous and noncancerous adverse health effects are expected to occur. Table 18 lists the exposed populations and their exposure durations. Contaminants of concern at the Industrial Landfill are similar to contaminants at the Bay Fill Area.

Industrial Landfill and the Bay Fill Area will be referred to as the landfill area. Industrial Landfill data was used to calculate the dose. The Industrial Landfill was capped with 4 to 5 feet of clean soil after operations ceased in the early 1970s (89). Current soil samples show that most of the contamination starts below the cap. People were exposed to contaminants in landfill soil before the cap was in place, so ATSDR used soil concentrations below the cap to calculate the dose. Additionally, ATSDR used the 95% upper confidence limit of the arithmetic mean (calculated by the Navy) to calculate the soil exposure dose because people most likely moved throughout the landfill area and the mean best represents how contaminants would have been distributed throughout the landfill.

Table 18. Estimated Exposure Durations at IR-1/21 and IR-2
Exposed Population Estimated Days/Week Estimated Weeks/Year Estimated Years Estimated Hours/Day1 Comments
Landfill Operators 5 50 16 8 Landfill workers were most likely present and participating in the original disposal actions.
Triple A Workers 5 50 10 1 Triple A Machine Shop occupied HPA from 1976 to 1986; during that period, the property was leased to various small businesses. Before the Navy installed a fence in 1991, Triple A and other base tenants had access to the landfill area. There are several Triple A sites in the landfill area.
Navy Personnel 1 48 3 2 Unmarried naval personnel stationed at HPA and staying at the BEQ for a single 3-year tour of duty may have engaged in recreational activities (e.g., basketball or volleyball) on the landfill on an occasional basis
Navy Children 3 48 3 1 Children in base housing may have played along the shoreline.
Tenants 2 6 15 1 Tenants may have scavenged in the landfill area. Parcel was fenced in 1991.
Trespassers 2 6 40 2 Trespassers can gain access to the landfill area by foot or boat.
1Hours are used to calculate the radiation dose.

Polychlorinated Biphenyls (PCBs)

Landfill operators, Triple A workers, trespassers, tenants, navy personnel, and their children were exposed to PCBs at levels of public health concern. Their exposures may result in cancerous and noncancerous health effects.

PCBs were detected in soils in the landfill area at a mean concentration of 4,259 ppm. In the past, landfill operators or anyone entering the area could have incidently ingested or have had dermal contact with PCB contaminated soils. Their estimated exposure doses are the following:

Population Estimated PCB Exposure Dose Cancer Risk
Landfill Operators
Triple A Workers
Base Tenants and Trespassers
Navy Personnel
Navy Children
0.020992 mg/kg/day
0.004198 mg/kg/day
0.000182 mg/kg/day
0.000791 mg/kg/day
0.006921 mg/kg/day
1.61 x 10-1
3.23 x 10-2
1.41 x 10-3
6.09 x 10-3

EPA has classified PCBs as Class B2 -- probable human carcinogens by the oral route (92) Information on human health effects associated with chronic oral exposure to PCBs is inadequate and inconclusive. The B2 classification was prompted by animal data. Oral toxicity studies in animals have established that the liver and skin are primary target organs of PCBs (93). Animal exposure to PCBs resulted in liver cancer, leukemia, lymphomas, and gastrointestinal tract tumors. Using EPA's cancer slope factor, exposure to PCB-contaminated soil by incidental ingestion at the landfill area is expected to result in cancer-related health effects in workers and adults. ATSDR estimated the cancer risk for the exposed populations. All populations are at an increased risk of developing cancer. Cancer risk is calculated as 1 excess cancer case above the normal background incidence for every x (risk level) exposed people over a lifetime. For example, landfill operators are expected to have one excess cancer case for every 10 exposed people over a lifetime.

The daily estimated exposure for all exposed populations exceeded the chronic MRL of 0.00002 mg/kg/day. Therefore, their exposure to PCB-contaminated soil at the landfill area is of public health concern and could result in adverse noncancerous health effects.

Although exposure to PCBs by dermal contact has not been evaluated by ATSDR, laboratory studies show that PCBs can be absorbed through the skin from contaminated soil (93). Reports from literature document that people have developed chloracne, redness, and skin rashes from PCB exposure (93). Therefore, exposures of people to PCBs by ingestion and dermal contact may result in greater risk of developing adverse health effects.

Polycyclic Aromatic Hydrocarbons (PAHs)

People (i.e. landfill operators, Navy personnel and their children, tenants and trespassers) were exposed to PAHs at the landfill area by incidentally ingesting soil. Their exposure puts them at greater risk of developing cancer. Noncancerous health affects are not likely although more research on the noncancerous health effects of PAHs is needed.

Cancer is the most serious endpoint of toxicity resulting from exposure to PAHs. Cancers associated with PAHs include skin, lung, urologic, gastrointestinal, laryngeal, and pharyngeal. Most information about cancer association comes from studies of occupational exposure.

PAHs are a class of compounds that may be carcinogenic and/or non-carcinogenic. The carcinogenic PAHs detected in surface soil at the landfill area include benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, and dibenzo(a,h)anthracene. Non-carcinogenic PAHs include naphthalene, 2-methylnaphthalene, and phenanthrene.

Benzo(a)pyrene is considered to be one of the most carcinogenic forms of PAHs. Therefore, the potential for cancer-related health effects has been evaluated by adjusting the total carcinogenic PAHs detected at the landfill to an equivalent concentration of benzo(a)pyrene using toxicity equivalency factors (TEFs) (94). After adjustment with TEFs, the daily estimated exposure to carcinogenic PAHs is the following:

Total Carcinogenic PAHs

Population Estimated PAH Exposure Cancer Risk
Landfill Operators
Triple A Workers
Base Tenants and Trespassers
Navy Personnel
Navy Children
0.000252 mg/kg/day
0.000050 mg/kg/day
0.000002 mg/kg/day
0.000009 mg/kg/day
0.000083 mg/kg/day
1.84 x 10-3
3.68 x 10-4
1.60 x 10-5
6.90 x 10-5

Using the EPA's cancer slope factor for benzo(a)pyrene (92), exposure of landfill operators and Triple A workers were exposed to PAHs by incidental ingestion of soil at the landfill area at levels that could result in cancer-related health effects. ATSDR estimated the cancer risk for the exposed populations; landfill operators are at the greatest risk. Children are also at a greater risk of developing cancer.

Because those PAHs are mixed together in the soil, and interaction among PAHs is common, the health effects of exposure to total PAHs are discussed. Using the mean concentrations detected (IR-1/21) for individual PAHs, the total PAH soil concentration is 467.2 ppm, total carcinogenic PAH concentration is 66.7 ppm, and total non-carcinogenic PAH concentration is 400.5 ppm.

Daily exposure from incidental ingestion of PAHs in the surface soil would result in the following estimated exposures:

Total PAHs

Population Estimated Non-Carcinogenic PAH Exposure Dose
Landfill Operators
Triple A Workers
Base Tenants and Trespassers
Navy Personnel
Navy Children
0.002302 mg/kg/day
0.000460 mg/kg/day
0.000020 mg/kg/day
0.000086 mg/kg/day
0.000759 mg/kg/day

Safe limits for exposure to PAHs by ingestion have not been established. However, people exposed to PAHs in nonoccupational settings have not experienced noncancerous health effects (95). Chronic dermatitis and hyperkeratosis have been seen in workers exposed to substances that contain PAHs. However, those exposures were at much greater concentrations than those expected from landfill area. Therefore, exposure to the concentrations of PAHs in soil at the landfill area is not expected to result in adverse noncancer health effects in adults and children.

Absorption of PAHs from soil by skin contact is expected to be minimal. Studies of dermal absorption in people reported only 3% permeation of an applied dose of benzo(a)pyrene (a member of the PAH family of compounds) after 24 hours. Therefore, skin contact with PAH-contaminated soil at the landfill area is not expected to result in adverse noncancerous health effects.

In general, PAHs can be converted enzymatically in the human body to less toxic substances (95). However, people with altered metabolic ability (increased Phase I enzymes, decreased Phase II enzymes, decreased efficiency of DNA-repair) may be more susceptible to the toxic effects of PAHs. Fetuses are particularly susceptible because of a decreased liver enzyme-conjugating function. People with deficiencies in vitamins A and C, iron, and riboflavin also may be at an increased risk for toxic effects related to PAHs. Smoking cigarettes and receiving excessive exposure to ultraviolet radiation (sunlight) are other factors that may result in increased sensitivity to PAH exposure.


People were exposed to lead contaminated soil at the landfill, but ATSDR is not able to predict the health consequences of this exposure. Lead can cause cancer and noncancerous health effects. However, studies of people exposed to lead have not established concentrations in soil that result in blood lead concentrations associated with adverse noncancerous health effects. Therefore, criteria for protecting public health have not been determined for lead-contaminated soil.

Some animal studies have linked exposure to lead with cancer; as a consequence, EPA has classified lead as a probable human carcinogen (B2) (96). However, the cancer risk in humans associated with exposure to lead contaminated soil at the landfill cannot be evaluated because there are no cancer-related environmental comparison values.

Lead was detected at a mean concentration of 3,114 ppm in surface soil at the landfill area and resulted the following exposure doses:

Population Estimated Lead Exposure Dose
Landfill Operators
Triple A Workers
Base Tenants and Trespassers
Navy Personnel
Navy Children
0.015347 mg/kg/day
0.003069 mg/kg/day
0.001327 mg/kg/day
0.000578 mg/kg/day
0.005060 mg/kg/day

The National Academy of Science has established 3 mg/wk for adults and <3 mg/wk for children as the Acceptable Daily Intake (ADI) for lead (96). Assuming 100% absorption from soil, using the estimated dose, the daily estimated exposure of landfill workers would be about 250% of the ADI. Even though exposures would occur only five days a week and 100% absorption from soil is unlikely, exposures still exceed the ADI and adverse noncancerous health effects may be expected.

Studies on lead's health effects are based on blood lead levels (µg/dL, micrograms per deciliter), not the amount of lead detected in an environmental medium. The health effects of lead are not immediately apparent. Once in the blood, lead is distributed to soft tissue (kidneys, bone morrow, liver, and brain) and mineralizing tissue (bones and teeth). Bones and teeth contain about 95% of the total body burden of lead in adults (96).

Because the body accumulates lead over a lifetime and releases it slowly, even small doses of lead over time can cause lead poisoning. It is the total body burden of that is related to the risk of adverse health effects.

Exposure to high levels of lead can badly damage the brain, red blood cells, and kidneys of adults whose blood levels range from 40 - 100 µg/dL. Acute effects of exposure to high lead levels are nausea, vomiting, and headache. Lead exposure in adults may increase blood pressure. High levels of blood lead (40 µg/dL) may affect sperm or damage other parts of the male reproductive system making it difficult for a couple to have children (96).

The potential for exposure to lead from skin contact is considered insignificant because little lead passes through the skin (96). Therefore, adverse health effects of skin contact with lead- contaminated soil at the landfill area are not expected.

At the landfill area, children's daily intake from incidental ingestion of soil is less than the ADI. Children are especially sensitive to lead's toxicity. Because lead is ubiquitous in the environment, many children have elevated blood lead concentrations approaching those believed to cause adverse health effects (10 µg/dL) (96). As a result, any additional exposure to lead may be potentially harmful. However, the level of lead exposure from incidental soil ingestion at which adverse health effects are expected has not been determined. Therefore, the possibility of adverse health effects among children exposed at this site cannot be ruled out.

The most sensitive target of lead poisoning is the nervous system. Neurologic deficits caused by lead may be irreversible. The developing nervous system in children can be adversely affected at blood lead levels of even less than 10 µg/dL. Effects of lead exposure in children include deficits in IQ score, cognitive function, psychometric intelligence scores, speech and language processing, attention span, hearing acuity, motor skills, reaction time, and hand-eye coordination (97).

Antimony, Arsenic, Copper, and Vanadium

In the past, at the landfill area, people (i.e., landfill operators and children) were exposed to antimony (98), arsenic (99), copper (100), and vanadium (101). ATSDR looked frequency and duration of exposure and concentrations of antimony, arsenic, copper, and vanadium in landfill soil and determined that exposures were not at a level of health concern. Adverse health effects from those exposures are not expected.

B. Radiologic Evaluation

ATSDR researched the scientific literature to determine the possible health effects of radionuclides. For information about radiological hazards, ATSDR researched the International Commission on Radiological Protection (ICRP) publications. ICRP's basic responsibility is to provide guidance in matters of radiation safety by preparing recommendations on the basic principles of radiation protection. The recommendations are published in reports and various journals (e.g., publications of the ICRP, Annals of the ICRP, Reports of the ICRP).

For purposes of radiation safety standards, ICRP recognizes three categories of exposure: occupational, public, and medical. For members of the public, ICRP recommends an effective-dose limit of 1 mSv (100 mrem) above background in a year (54). (That limit is for the purposes of radiation protection only. No adverse health effects have been directly attributed to a radiation exposure at that level.) ICRP does not make recommendations for medical exposures. However, the Commission does recommend that people receive only necessary exposures and that exposures be limited to the minimum dose necessary for medical benefit to the patient.

The current ICRP recommendations specify an annual limit on intake defined as the amount of radionuclide that delivers the occupational effective-dose limit from ingestion or inhalation exposures. Occupational annual limit of intake is calculated using the average career span of an occupationally exposed person -- 50 years. ICRP recommends using the average lifetime of an individual (70 years), and the public's effective-dose limit, 1 mSv (100 mrem) per year, to determine the public's annual limit of intake by way of ingestion or inhalation.

Dose is usually divided into two categories, external and internal. External doses result from exposure to radioactive sources outside the body; internal dose result from exposure to radioactive sources inside the body.

Whether an exposure contributes to a person's external or internal dose, depends primarily on the type of radiation to which a person is exposed. Alpha particles cannot travel far and are prevented from entering the body by skin. Therefore, exposures to alpha particles would not contribute to a person's external dose; if an alpha particle source is within the body, it would contribute to a person's internal dose. Beta particles also may be responsible for both internal and external doses, but they do not penetrate body tissue as easily as gamma rays, limiting the dose from external sources. Gamma rays can travel long distances and can easily penetrate body tissues; therefore, people can be exposed to gamma rays through external or internal sources. The total dose is the sum of a person's external and internal doses.

For internally deposited radionuclides, ATSDR's quantitative evaluation of exposure to adults and children considered media-specific rates for soil ingestion and of inhalation. The radiation doses were calculated by multiplying the ingestion or inhalation rate by the soil or air concentration. This estimated annual intake was then compared to the public's ALI which infers the annual radiation dose to a hypothetical individual and adjusted for the appropriate standard child's weight 16 kg.

For soil and sediment, the ingestion rates used were 100 mg/day for adults, 200 mg/day for school-age children, and 500 mg/day for landfill operators (workers, due to their work related activities, could ingest a large amounts of soil). Some exposures were intermittent or irregularly timed. In those cases, an exposure factor (EF) was calculated that scaled the intake to appropriate levels.

For external exposures, ATSDR's quantitative evaluation of exposure to adults and children consisted of multiplying the gamma ray exposure factor for Ra-226 by the average source strength of the radium dials at HPA and the time spent in the contaminated area (see exposure scenarios). The resultant was then corrected for distance (one meter for adults and one-half meter for children) (see Appendix G for details).

The people exposed to multiple radionuclides at the HPA site were exposed by way of incidental ingestion of contaminated soil and by their proximity to radioactive sources. ATSDR's health effects evaluation of radionuclide contaminants considers the known additive effect of radiation on the human body. The contributing radiation dose from each radionuclide is calculated by specific exposure routes. Furthermore, simultaneous exposure to contaminants that are known or probable human carcinogens could increase the risk of developing cancer. ATSDR's evaluation of exposures in this public health assessment is limited to individual contaminants and individual routes of exposure; multiple exposures have not been evaluated.

On Site

ATSDR has determined that past Ra-226 exposure to on-site military, civilian, and tenant populations by way of ingesting contaminated soil is not of health concern. ATSDR has limited its discussion of exposure to radioactive materials in this public health assessment to Ra-226 because other contaminants in soil (americium, thorium, cesium, potassium, and plutonium) contribute less than 2% of the total internal dose.

Of the exposure scenarios described, the landfill operators had the greatest incidental exposure from soil ingestion. ATSDR has compared the concentration of radionuclides (in the soil) estimated to have been ingested by the landfill operators to the public's annual limit of intake and has determined that Ra-226 contributed about 98% of the effective-dose; the other radionuclides combined contributed about 2% of the effective-dose.

The internal effective-dose for those exposed at HPA would be as follows:

Exposed Population Ingestion Rate Calculated Internal Effective Dose
Landfill Operators
Triple A Workers
Base Tenants
Navy Personnel
500 mgsoil/day
200 mgsoil/day
100 mgsoil/day
100 mgsoil/day
100 mgsoil/day
100 mgsoil/day
8.02 mrem/year
1.15 mrem/year
1.00 mrem/year
0.48 mrem/year
0.10 mrem/year
0.04 mrem/year

The external dose of gamma rays radiating from the soil can be calculated by multiplying the estimated source strength of 1 µCi per radium source (18); the specific gamma dose constant for Ra-226 at one meter for adults (or at one-half meter for children); and the amount of time a person has spent in the contaminated area. The external effective-doses for the exposed populations described previously are as follows:

Exposed Population External Ra-226 Effective-Dose
Landfill Operators
Triple A Workers
Navy Personnel
Base Tenants
0.024 mrem/year
0.07 mrem/year
0.003 mrem/year
0.001 mrem/year
0.0003 mrem/year
0.0001 mrem/year

Because the internal doses of the exposed populations are much greater than the external doses, adding the two does not substantially change the total effective-doses for the circumstances described. Thus, external doses are insignificant. The total effective-doses for exposed populations are less than the 100 mrem/year above background (91) recommendation of the ICRP for limiting public exposures to radioactive material, and the health effects associated with those doses are unlikely. Therefore, exposure to Ra-226 by incidental or unintentional soil ingestion does not pose a health threat to the identified populations for the circumstances described.

Toxicological and Radiologic Evaluation Summary

In the past, people were exposed to PCBs, PAHs, lead, Ra-226, arsenic, antimony, copper, and vanadium at the landfill area (IR-1/21 and IR-2). Exposures to Ra-226, arsenic, antimony, copper, and vanadium are not of health concern. Past exposures to PCBs, PAHs, and lead are of health concern.

C. Health Outcome Data Evaluation

ATSDR conducts a review of health outcome data when completed exposure pathways have been identified; when the toxicologic evaluation indicates the likelihood of health outcomes; or when the community near the site has health concerns. Health outcome data for HPA are available at the state level; they include death, infant death, and birth rates for San Francisco County and for the state of California. Those data have been requested and will be evaluated as soon as they are received.

Other health outcome data sources at the state level, such as the California Tumor Registry and the California Birth Defects Monitoring Program, contain information on San Francisco County for 1973-1990, and 1986 - 1987, respectively (102) and (103). ATSDR has requested the most recent cancer and birth defect incidence data and will evaluate it as soon as it is received.

D. Community Health Concerns Evaluation

In this section, an evaluation is provided of the health-related community concerns. The following health concerns were voiced by the community and are addressed below:


Respiratory Disease

  • Have there been hazardous air emissions (asbestos etc.) from the shipyard that could have affected local residents?

    ATSDR believes that presently there is not a problem with hazardous emissions, except at one area of HPA. On base at an upwind background sampling station, pesticides and metals were detected in air samples. Pesticides were found at concentrations above comparison values at the western boundary of the base at a designated upwind background air monitoring station. The source of the pesticides is unknown. Asbestos was detected at low levels.

    The air sampling the Navy conducted was just a screening study; base-wide air sampling is incomplete. Ambient air monitoring during industrial activities was not standard practice during the 1950s and 1960s and was not required by state or federal law until 1977 (105). Navy contractors collected ambient air samples in 1984, 1987, and 1992 (62). In addition, ATSDR contacted the Bay Area Air Quality Management District which has an air monitoring station located approximately two miles from the Hunters Point Annex boundary. According to the representative, air quality in San Francisco County in general is very clean because of its geographical location between the Pacific Ocean and San Francisco Bay. In the last three years, only two samples from only two of the 30 air monitoring stations that the district runs in San Francisco and surrounding nine counties exceeded state and federal air quality standards for ozone concentration (106). Further, the representative added that, because the Hunters Point community is "right on the water, air quality is very good." Wind rose data indicate that the predominant wind direction is from the west to northwest, away from the Hunters Point/Bayview area.

  • A resident who worked at HPA during 1965 (and who still lives in the area) complained of odors in the air. He also with complained of respiratory problems. He said he was diagnosed with "pleurisy spots" in 1969 and asked if these could be caused by exposures he during the period he worked at HPA?

    Pleurisy spots or pleural plaques (areas in the membrane surrounding the lungs (pleura) that show thickened fibrous spots) have been proven to be linked with asbestos exposure and are referred to as "asbestos-related illness" or "asbestos-associated illness" (107). The development of nonmalignant forms of asbestos-induced pleural abnormalities is caused by repetitive exposures to high concentrations of asbestos over an extended time period (108). Sixty percent of workers exposed to high levels of asbestos have radiographic evidence of pleural disease including pleural plaques and pleural thickening (109, 110, 111, 112, 113). The condition is usually non-symptomatic, but can be identified by chest x-rays. Pleural plaques develop slowly with a latency period of approximately 15 years (113). Although the condition is normally mild, it can result in impaired respiratory function (114).

    However, ATSDR does not have sufficient information to determine if this resident's "pleurisy spots" are caused by occupational exposure incurred while working at HPA, because it is unknown if he came into contact with asbestos during his career. The resident's personal physician would need to differentiate between occupational or non occupational pleurisy. ATSDR is unable to measure the individuals past exposure. It is not likely at living near HPA can cause pleurisy.

  • A former HPA worker, who used to live in the Hunters Point/Bayview area, frequently visits relatives who still live in the area. During these visits, he experiences more respiratory problems such as allergies and asthmatic conditions. Could his respiratory problems be related to HPA?

    It is unlikely that ATSDR will be able to establish a correlation between the contamination at HPA and the asthmatic episodes people in the Hunters Point/Bayview area may be experiencing because of limited air data and because asthma has multiple causes.

    Asthma is a common illness which affects 5% of the U.S. population, an estimated 20 million persons (115). Asthma is a disease that causes the bronchial airways to narrow. It is diagnosed by the symptoms of cough (usually at night), chest tightness, wheezing, and shortness of breath. The causes of asthma are numerous. Asthma is caused by a wide variety of irritants. Allergic hypersensitivity is the leading cause of asthma. In these cases the most likely allergens found in food or substances frequently found in homes, such as animal danders, house dust mites, and cigarette smoke. However as ATSDR mentioned in our response to the opening question on air quality, San Francisco air quality and Hunters Point/Bayview air quality are quite good.

  • One resident stated that her husband, who worked at HPA for 30 years, developed asbestosis due to his occupational exposure. Could the asthma she experienced for many years have been caused by the dust he carried home from the shop or from living in the Hunters Point/Bayview area?

    ATSDR was not able to find any scientific association between "take home" asbestos and asthma. "Take home" refers to workers who take home occupational dust on their clothes and shoes. Asthma is a common disease caused by many types of substances; therefore without highly detailed information on present and past exposure to a wide variety of substances it is not possible to determine the cause of an individual's asthma.

    Although asthma has not been associated with asbestos exposure, it has been linked to allergies, dusts, and a wide variety of occupational chemicals including phenol, tannic acid, pyrethrins, dyes, formaldehyde, vinyl chloride and isocynates and metals such as platinum, nickel, stainless steel, chromium, and aluminum (116). Occupational asthma, however, usually requires a higher dose and longer period of exposure then one would expect to see from exposure to take home allergens. Therefore ATSDR believes the husbands exposure probably did not contribute to the wife's asthma.

    Occupations or industries that carry the highest risk of Occupational asthma are as follows:

    Occupation or Industry Cause of Asthma
    animal breeding and handling
    hair dressers
    coffee processors
    grain handlers
    lumber workers
    plastics industry
    metal workers
    industrial painters
    animals antigens
    yeasts, flour, mites
    sodium persulfate
    green coffee beans
    wood dusts
    metallic salt, fumes
    diisocynate paint

Morbidity and Mortality Rates

  • Were former HPA shipyard workers exposed to contaminants during their careers that could have led to a higher death rate?

    ATSDR was not able to find any mortality information specific for shipyard workers who worked at HPA. State databases do not routinely report data for areas smaller than the county level, specific rates cannot be calculated for smaller areas, such as the community neighboring Hunters Point Annex. However, ATSDR contacted the San Francisco City/County Public Health Department to obtain mortality information. For the time period of 1986 through 1990, the only elevated mortality rates were noted in age group 25 - 45 years of age and were most likely due to HIV/AIDS prevalence in that age group in the San Francisco County area (117).

    Some information does exist on occupational exposures in shipyard. In 1980, Dr. Robert Rinsky of the National Institute of Occupational Safety and Health (NIOSH) studied the mortality data from shipyard workers at Portsmouth Naval Shipyard in Kittery, Maine (118). Mortality data from 1978 showed a three-fold increase in the incidence of deaths among shipyard workers at the Portsmouth Naval Shipyard as compared to the U.S. population (119). Shipyard workers are exposed to asbestos, metallic fumes, solvents, paints and other chemicals and, because of the confined spaces in which many shipyard employees work, exposures to these chemicals is accentuated.

  • Could there be an additional increase in death rate among those workers who lived as well as worked in the Hunters Point/Bayview area?

    Because current sampling data do not show that residents in the neighboring Hunters Point/Bayview area are now being exposed or have been exposed in the past to environmental contamination from HPA, living in the Hunters Point/Bayview area should not pose any additional health threat or cause any increase in death rates among those residents. However, landfill operators who worked at HPA may have been exposed to contaminants that may have resulted in an increased risk of adverse health effects. Further discussion of exposure of on-base landfill operators is in the Toxicological Evaluation section of this document.

  • Is there a higher number of early deaths among the youths in the Hunters Point/Bayview community?

    Vital statistics information is not available for the specific community neighboring Hunters Point Annex. San Francisco City/County Public Health Department evaluated death rates for all leading causes of death for San Francisco County as compared to the State of California for the time period of 1986 through 1990. Elevated mortality rates were noted in age group 25 - 45 years of age, most likely due to HIV/AIDS prevalence in that age group in the San Francisco County area (117). No other elevated mortality rates were noted by the San Francisco City/County Public Health Department between 1986 and 1990.

  • Is the black infant mortality rate in the Hunters Point/Bayview area elevated? Could any elevated rate be caused by exposure to contaminants from Hunters Point Annex?

    The infant mortality rate among blacks in San Francisco County was not elevated compared to the state black infant mortality rate (121). ATSDR contacted the city/county health department and was not able to find mortality information specific for Hunters Point/Bayview area.

    National infant mortality rates among nonwhite persons are higher than the infant mortality rates among whites. These elevated mortality rates are thought to be due to the generally lower socioeconomic status of nonwhites, which is associated with infrequent prenatal care, low prenatal nutritional level, and low birth weight (122).

  • Could working at HPA during the 1970s have caused any adverse health effects?

    In order for ATSDR to answer this question, more specific information is needed i.e., what type of work an employee performed and how long. Certain occupations such as metal working and insulators do bring in employees in contact with hazardous chemicals and dusts if precautionary safety equipment (e.g., respirators) are not worn. But adverse health effects depend on the specific hazardous substances used, the amount of exposure, and the duration of exposure.

    In 1970, Congress passed safety legislation to protect workers, the Occupational Safety and Health Act (OSHAct). The OSHAct (clause-Section 5(a)(1)- requires each employer to provide "employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to employees."

  • A resident knew of a cancer cluster investigation near San Francisco, but was not sure of the details. Was there a cancer cluster in the Hunters Point/Bayview area?

    Although the cancer incidence data for the city/county of San Francisco is routinely analyzed, no cancer clusters in the HPA area have been found. Between the years of 1973 and 1985, a higher than expected incidence of cancer was found in the Noe/Eureka Valley area of San Francisco (3 miles from Hunters Point/Bayview), which prompted further investigation. To investigate this finding further, in 1989, the Bureau of Disease Control, San Francisco Department of Public Health performed a cancer cluster investigation of children four years old and younger in Noe Valley between 1973 and 1985. However, findings from the study were inconclusive.

  • Could the number of deaths in the community due to colon cancers be related to exposures to contaminants from HPA?

    ATSDR does not have sufficient information to determine if colon cancer in the community is related to exposures to contaminants at HPA. Asbestos has been linked to intestinal cancer but, ATSDR does not have information that leads us to believe that residents were exposed to asbestos from HPA. Further lifestyle factors are associated with colon cancer. Therefore, to be able to determine an association ATSDR would need to know lifestyle information and past exposure information on all persons diagnosed with colon cancer.

    Further, the leading causes of colon cancer are specifically linked to dietary and lifestyle factors such as low fiber, high fat diets. Asbestos exposure has been associated with different forms of intestinal cancers. Community exposure to contaminants from HPA has not been identified.


  • Is the groundwater at HPA contaminated? Could the health of people in the surrounding community be affected?

    Even though contaminants have been detected in groundwater (in the shallow aquifer), it is highly unlikely that this has affected or will affect local residents. Groundwater in the HPA area moves out towards the bay. All residents, would therefore be upgradient of the contaminated groundwater plume, and would not likely be affected by the groundwater contamination. In addition, most residents receive water from the city water department which obtains water from Yosemite National Park. Thirty-four wells are known to exist within two miles of HPA. Seven wells are known to be in use: of these, three were installed for residential irrigation, two wells for monitoring purposes (cathodic protection), and two for industrial uses. However, at this time the number of residents using well water as their primary drinking water source is unknown but, ATSDR believes it is limited. Further, even if people are using groundwater the risk of contamination is further decreased by the patterns of groundwater movement away from Hunters Point/Bayview. However, ATSDR recommends that the Navy perform a thorough well survey of the surrounding area to ensure that the public is not using contaminated groundwater.

  • Why has environmental sampling not been performed off site in the neighborhoods surrounding the base?

    According to the Navy, off-site sampling has not been performed at this time because sampling data do not indicate that contamination has or could possibly migrate off HPA into the neighborhoods (123). However, sampling is in the initial stages; if sampling data suggest that contamination may have migrated or could potentially migrate into those neighborhoods, ATSDR will recommend that the affected neighborhoods be sampled to ensure the protection of public health.

  • Can children playing in the area between the southwestern boundary of HPA and Candlestick Park be exposed to contaminants emanating from HPA?

    The HPA boundaries are fenced and all soil contamination has been found to be within those boundaries. Currently, there is no evidence that contaminants have migrated off site. Therefore, children outside HPA boundary would not be exposed to environmental contaminants at HPA.

  • One resident reported that in the past, children were seen playing in piles of waste asbestos in the surrounding neighborhoods. Could those children suffer from adverse health effects?

    ATSDR does not have sufficient information to determine if children exposed to the material could suffer adverse health effects. To determine if children were exposed to the asbestos, we would need to know the following information: where the asbestos came from (construction debris containing asbestos or mine tailings of naturally occurring asbestos); what type of asbestos was present, [friable (crumbles easily) or non-friable]; the percent of asbestos present in the waste; how long the material was in the neighborhood; and how long the children played in the material.

  • Local residents and personnel from the city of San Francisco questioned how Installation Remediation areas will be designated clean for industrial use.

    Regulatory agencies such as U.S EPA, California State EPA, California Department of Toxics, and California Water Quality Control Board oversee the cleanup activities at HPA to ensure that cleanup levels achieved are appropriate for the intended future use.

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