PRELIMINARY PUBLIC HEALTH ASSESSMENT
DEL AMO FACILITY
LOS ANGELES, LOS ANGELES COUNTY, CALIFORNIA
In this section we will discuss the health effects in persons exposed to specific contaminants, evaluate state and local health data bases, and address specific community concerns.
In evaluating health effects, several factors determine whether harmful effects will occur and the type and severity of those health effects. These factors include the dose (how much), the duration (how long), the route by which people are exposed (breathing, eating, drinking, or skin contact), the other contaminants to which they may be exposed, and their individual characteristics such as age, sex, nutrition, family traits, life style, and state of health. The scientific discipline that evaluates these factors and the potential for a chemical exposure to adversely impact health is called toxicology.
In order to determine whether adverse health effects are possible as a result of exposure to a contaminant, an exposure dose must be estimated for each pathway. This exposure dose can then be compared with appropriate toxicity values in order to evaluate the likelihood of adverse health effects occurring. Toxicity values used to evaluate noncancer adverse health effects include ATSDR's Minimal Risk Level (MRL) and EPA's Reference Dose (RfD) for ingestion and Reference Concentration (RfC) for inhalation. The MRL, RfD, or RfC values are estimates of daily human exposure to a contaminant below which noncancer, adverse health effects are unlikely to occur.
The National Toxicology Program (NTP), the International Agency for Research on cancer (IARC), and EPA have reviewed available information from human and/or animal studies to determine whether certain chemicals are likely to cause cancer in humans(36,37,38). The potential for cancer to occur in an individual or a population is evaluated by estimating the probability of an individual developing cancer over a lifetime as the result of the exposure. EPA has developed cancer slope factor values for many carcinogens. A cancer slope factor is an estimate of a chemical's potential for causing cancer. If adequate information about the level of exposure, frequency of exposure, and length of exposure to a particular carcinogen is available, an estimate of excess cancer risk associated with the exposure can be calculated using the cancer slope factor for that carcinogen. Cancer risks from pathways involving multiple contaminants are added together and the overall cancer risk from multiple pathways is evaluated.
Cancer risk is the likelihood, or chance, of getting cancer. We say "excess cancer risk" because we have a "background risk" of about one in four chances of getting cancer from all other causes. In other words, in a million people, it is expected that 250,000 would get cancer from a variety of causes. If we say there is a "one-in-a-million" excess cancer risk from a given exposure to a contaminant, we mean that if one million persons are exposed to a carcinogen at a certain level over their lifetime, then one cancer above the background chance, or the "250,001st" cancer, may appear in those million persons from that particular exposure. In order to take into account the uncertainties in the science, the risk numbers used are plausible upper limits of the actual risk based on conservative assumptions. In actuality, the risk is probably somewhat lower than that calculated, and in fact, may be zero.
Toxicology of Contaminants Selected for Follow-up
The contaminants associated with the Del Amo site which are selected for follow-up mainly include VAHs, PAHs, and metals.
The VAHs of concern include benzene, ethylbenzene, toluene, and xylene. Exposure to these contaminants through inhalation probably occurred and may still be occurring to residents and workers in the area through ambient air and possibly through indoor air. Other contaminants of concern for the ambient air pathway include styrene and naphthalene, a PAH that evaporates or volatilize easily, as well as particulates such as metals. The existing information about releases of these contaminants to ambient air is not sufficient to determine accurate exposure doses for residents or workers and thus draw conclusions about possible health effects. Releases from other non-site related sources, such as vehicular emissions, petroleum refineries, and other industrial facilities in the area can also contribute to levels for the area and interfere with the estimation of exposure to contaminants released from the site. The general air quality in the area can be negatively affected by these sources. Additional air monitoring data will be necessary to determine possible exposure point concentrations of site-related contaminants in ambient air. Levels of air contaminants currently reported for the general Los Angeles area can affect individuals who are susceptible to respiratory problems such as asthma.
Further determination of the concentrations of the VAHs in the groundwater and soil gas underneath the residences south of the site and other structures north of the waste disposal area and indoor air monitoring are also needed. A confounding factor to consider in indoor air monitoring is that benzene, ethylbenzene, toluene, and xylene are typically found in indoor air because they are used in materials like carpet glue and varnishes. They are also formed when a gas oven or heater is used. Estimates of exposure doses from all involved pathways will allow a better determination about possible public health implications. Information presented below on benzene, ethylbenzene, toluene, xylene, naphthalene, and styrene is taken from ATSDR's Toxicological Profiles for the chemicals(39-44).
Residents and workers probably experienced and may still be experiencing exposure to PAHs through ingestion, inhalation, and possibly skin contact through the soil pathway. There is currently not enough information available to allow for complete dose estimations or evaluation of health effects. PAHs were not detected in 0-1' soil samples taken from residential yards. No soil samples less than 5' were analyzed for the waste area. Sampling for particulates in air and house dust and surface soil sampling in the waste disposal area, other areas of the 280-acre site, the unpaved Del Amo Boulevard, as well as in residential yards, are necessary before actual exposure can be determined. Use of mathematical models to determine whether environmental transport mechanisms could result in past and future exposures may be helpful also. Information taken from ATSDR's Toxicological Profile on PAHs is presented below(25).
Residents and workers may also have experienced and may still be experiencing exposure to the metals arsenic, barium, cadmium, chromium, copper, nickel, and zinc through the soil pathway. These metals are present in the waste/soil in the waste disposal area and in residential yards. Industrial air releases of chromium, lead, and copper compounds for the area are also reported in the Toxics Release Inventory. Although no surface soil data exist, we used maximum concentrations present in 0-1' samples from residential yards to estimate exposures from ingestion to residents. Assuming a 30 year average exposure scenario where an individual incidentally consumes 200 milligrams per day (mg/day) of contaminated soil during the first six years of life and 100 mg/day from 6-30 years, the chronic daily intakes for arsenic, barium, cadmium, chromium, and nickel did not exceed their respective RfD values. No MRL or RfD values are currently available for zinc, copper, or lead. The levels of these metals reported for the residential yards are similar to levels reported for native soil in the western United States and probably would not produce adverse health effects. Additional surface soil sampling, similar to that needed for PAHs, can provide additional information that can be used to derive more accurate exposure doses.
Since chromium(III) and chromium(VI) have different health implications and toxicity values, information from ATSDR's Toxicological Profile for chromium is presented below(45).
Another contaminant present in the waste pits and ponds is 1,1'-biphenyl. ATSDR has not developed a Toxicological Profile for it and only limited information about it is available(46).
Exposure to benzene for residents and workers in the area during disturbed site conditions probably occurred in the past and may occur during future site activities. Downwind concentrations of 0.1443 ppm benzene detected in one sample collected during 1984 soil boring activities did not exceed levels at which people normally can smell benzene (1.5 to 4.7 ppm), but did exceed ATSDR's acute inhalation MRL of 0.002 ppm for exposures of 14 days or less(39). (No chronic MRL for exposures greater than 365 days is currently available.) Benzene concentrations probably were higher closer to the waste area where boring occurred. It should also be noted that the 1984 upwind sample (0.03 ppm) and the 1990 benzene air data (0.0014 to 0.011 ppm) available from the Long Beach monitoring station also exceeded the acute MRL of 0.002 ppm(39).
Benzene is also present in soil gas detected around the waste disposal area. The highest hydrocarbon concentrations detected were taken at 10' and 12.5' (31,300 ppm and 48,500 ppm respectively). Up to 920,000 ppb benzene has been reported to exist in a floating layer in shallow groundwater beneath residences. The data regarding soil gas emissions during undisturbed site conditions can not be used to draw conclusions about releases to ambient air because testing and equipment problems were noted (see Environmental Contamination Section - Ambient Air section). No information currently exists about indoor air or ambient air specific to the Del Amo area.
Data currently available do not allow for determination of soil gas releases to ambient air or indoor air. At this time it is not possible to accurately quantitate the level of benzene that residents and workers may have experienced during disturbed site conditions or may currently be experiencing during undisturbed conditions. The higher levels seen during disturbed site conditions may present a more immediate health concern to remediation workers who are working in the waste disposal area and to the nearby residents, especially those directly across from the waste pit area. Air monitoring in the residential area and the affected site area during future activities where there is excavation or uncovering of waste materials or contaminated soils will help to ensure that unacceptable exposures do not occur. Measures to control excessive emissions as well as contingency plans to protect people from unacceptable exposures should be developed before site conditions are disturbed.
Chronic health effects may result from long-term low level exposure to benzene exposure that may be occurring at the Del Amo site(39). Additional monitoring of soil gas, indoor air, and ambient air levels are needed before more definitive conclusions about possible health effects can be made.
Benzene is commonly found in the environment and most people are exposed to a small amount of benzene daily. Exposure for most people is mainly through breathing contaminated air. The major sources of benzene exposure include gasoline stations, car exhaust, industrial emissions, and tobacco smoke. Some common household products like furniture wax, paints, or glue can also contain benzene(39).
Reported background air levels of benzene in the United States range from 0.0028 to 0.02 ppm. (The 1990 levels reported for the Long Beach station are similar to these figures.) People living in cities or industrial areas generally are exposed to higher levels of benzene than those living in rural areas. Also people living near petroleum refining operations or gas stations may be exposed to higher levels of benzene in air. Benzene levels in homes are usually higher than outdoor levels(39).
Health effects associated with benzene exposure will vary depending on the amount of benzene and the length of time of the exposure. Most of the data on the effect of long-term exposure to benzene come from studies of workers employed in industries that make or use benzene. Exposure levels in air for these workers were much higher than levels normally encountered by the general public. Long-term health effects seen in workers include blood disorders, immune system effects, and possibly damage to reproductive organs. Studies with pregnant animals show that breathing benzene can affect the developing fetus. Observed adverse effects in animals include low birth weight, delayed bone formation, and bone marrow damage. Similar effects for pregnant women and their babies have not been shown. EPA, NTP, and IARC have determined that benzene is a known human carcinogen. Long-term exposure to high levels of benzene in air can cause cancer of the tissues that form white blood cells (leukemia). Exposure to benzene has also been linked with genetic changes(39).
Past, present, and future exposure of residents and workers to ethylbenzene is likely given the known releases during disturbed site conditions, current industrial releases in the area, and available ambient air levels. The level detected during the 1984 soil boring (0.0117 ppm) and the 1990 Long Beach data (0.0006 to 0.0017 ppm) do not exceed ATSDR's intermediate MRL of 0.3 ppm for exposures of 15 to 365 days, nor EPA's chronic RfC of 1 milligram per cubic meter of air (mg/m3) (equivalent to 0.23 ppm), which applies to lifetime exposures(40). Adverse non-cancer health effects are unlikely at levels below the MRL or RfC. Releases are likely under disturbed site conditions and measures should be taken to prevent unacceptable exposures to nearby residents and remediation workers.
Ethylbenzene is a colorless liquid that smells like gasoline. Like most volatile aromatic hydrocarbons, it moves easily into air from water and soil and is most commonly found as a gas in air. People can smell ethylbenzene in the air at concentrations as low as 2 ppm. Reported levels of ethylbenzene in urban areas is about 0.00062 ppm and 0.00001 ppm in rural areas. Common sources of ethylbenzene include gasoline, pesticides, varnishes and paints, and tobacco products(40).
Short-term exposure to low levels of ethylbenzene can result in eye and throat irritations. Exposure at higher levels can lead to dizziness. Health effects related to long-term exposure to ethylbenzene are largely unknown. Due to lack of animal or human data, neither IARC, NTP, nor EPA has determined its carcinogenicity class(40).
Past, present, and future exposure of residents and workers to toluene is likely given the known releases during disturbed site conditions, current industrial releases in the area, and available ambient air levels. The levels detected during the 1984 soil boring (0.0117 ppm) and the 1990 Long Beach data (0.0025 to 0.0029 ppm) do not exceed ATSDR's intermediate MRL of 1 ppm for exposures of 15 to 365 days, nor EPA's chronic RfC of 0.4 mg/m3 (0.106 ppm) for a lifetime exposure(41). Adverse non-cancer health effects are unlikely at levels below the MRL or RfC. Releases are likely under disturbed site conditions and measures should be taken to prevent unacceptable exposures to nearby residents and remediation workers.
Toluene is a clear, colorless liquid with a sweet smell. Widely used in industry as a solvent, it is also commonly found in gasoline and as a by-product of styrene production(41).
People can be exposed to toluene in the air when toluene containing products are used. Consumer products containing toluene include gasoline, nail polish, cosmetics, stain removers, inks, and adhesives. Car exhaust and cigarette smoke are also sources of toluene. Toluene levels in air are typically lower than 1 ppm. It can be smelled in air at a level of about 0.16 ppm(41).
Exposure to toluene can lead to harmful effects on the central nervous system. These effects depend on both the amount and length of exposure. Short-term exposure to moderate amounts (300-600 ppm) of toluene sometimes seen in the workplace can produce fatigue, confusion, memory loss, nausea, and loss of appetite and coordination. These symptoms disappear when exposure is stopped(41).
Long-term exposure to low and moderate amounts of toluene has caused slight effects on the kidneys in some people, but these people were also exposed to other solvents at the same time and it is difficult to tell which chemical may have caused the effects. Long-term exposure to high amounts of toluene through intentional use has been linked with permanent brain damage. The NTP, IARC, and EPA have not determined its carcinogenicity classification due to lack of available information(41).
Although not reported in the 1984 ambient air sample data, it is likely that releases of xylene are possible during disturbed site conditions since it is present in the waste materials and is probably present in the soil gas. The available TRI information also reports industrial releases to ambient air. Neither ATSDR nor EPA have MRL or RfC values for xylene(42).
Xylene usually consists as a mixture of three xylene isomers, or chemical forms. Used primarily as a solvent, xylene evaporates easily into air. People can smell xylene in air at levels ranging from 0.1 ppm to 2.0 ppm. Releases to the environment primarily occur through industrial sources, car exhaust, and use of solvents. Xylene is commonly found in cigarette smoke, gasoline, paint, and rust preventives(42).
Short-term exposure of humans to high levels of xylene (100-299 ppm) or chemical mixtures containing xylene causes irritations of the skin, eyes, nose and throat; breathing difficulties, impaired memory, stomach discomfort, and possible changes in the liver and kidneys. Short-term and long-term exposures to high concentrations can result in central nervous system effects, such as headaches, lack of muscle coordination, dizziness, and confusion. The health effects resulting from long term exposure of humans to air containing specific levels of xylene are mainly unknown, but liver changes, nose and throat irritations, and decreased body weight have been noted. The EPA, NTP, and IARC have not determined its carcinogenicity class due to insufficient information(42).
Polycyclic Aromatic Hydrocarbons (PAHs)
PAHs are a group of chemicals formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances. There are over a hundred different PAH compounds. ATSDR discusses the following PAHs in its Toxicological Profile for PAHs: acenaphthene, acenaphthylene, anthracene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-cd)pyrene, phenanthrene, and pyrene. All of these PAHs are associated with the Del Amo site. It is not possible to quantify past or present exposures that residents and workers may have to any of these PAHs since no surface soil or air data exist. For most of the PAHs, no MRL, RfD or RfC values are available(25).
Found commonly in the environment, PAHs usually occur as a mixture. They can occur in air attached to dust particles, or in soil or sediment. Suspended in air, they can deposit on surfaces through rain. They are also found in crude oil, coal, creosote, and road and roofing tar. Most PAHs do not dissolve easily in water. Some readily evaporate as a gas into the air. Background levels of PAHs in air are reported to be 0.15-19.3 (mg/m3) in urban areas, and 0.02-1.2 mg/m3 in rural areas(25).
Human exposure to PAHs commonly occurs by inhaling PAH-containing vapors or dust and other particles in the air. Other sources include vehicle exhaust, asphalt roads, tobacco smoke, smoke from wood burning fires, and many foods and beverages. Some PAHs can be absorbed by vegetables grown in soils containing PAHS. Cooking meat or other foods at high temperatures, such as during grilling, increases the amount of PAHs in the food(25).
The health effects resulting from long-term exposure of humans to air, food, or water containing specific levels of PAHs are largely unknown. However, inhalation and skin exposure to mixtures containing PAHs has been associated with cancer in humans. EPA has determined that several of the PAHs, including benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, and indeno(1,2,3-cd)pyrene are probable human carcinogens based on animal studies. IARC has classified benzo(a)anthracene, benzo(a)pyrene, and dibenzo(a,h)anthracene as probable human carcinogens; and benzo(b)fluoranthene, benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene as possible human carcinogens. Due to insufficient studies, IARC has not classified anthracene, benzo(g,h,i)perylene, chrysene, fluorene as to their carcinogenic effect on humans. For NTP, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, and indeno(1,2,3-cd)pyrene may reasonably be anticipated to be carcinogens(25).
Other animal studies have shown that benzo(a)pyrene fed to pregnant mice resulted in birth defects and decreased birth weight. No information exists to show that humans could be affected in a similar way(25).
Humans are usually exposed to PAHs in complex mixtures rather than as individual PAHs. Interactions between different PAHs and other possible components may occur that can either retard or enhance the development of health effects, particularly cancer. Information about these interactions and their effects on humans is not complete. However, effects have been demonstrated in animals. Several experiments have shown that most PAH mixtures are considerably less potent than individual PAHs. Much more research needs to be done regarding the health effects related to mixtures of PAHs before definitive conclusions can be drawn(25).
Naphthalene is a white solid substance with the characteristic odor of tar or mothballs. It can be released to air in cigarette smoke and also from burning of fuels such as coal and tar. After its release to air, humidity and sunlight cause it to break down within a few hours. Typical air concentrations of naphthalene in cities is about 0.0000001 ppm. It can be smelled in air at about 0.08 ppm(43). Residents across from the waste disposal area could have noted odors related to naphthalene during excavation activities for waste pond 1A since total hydrocarbon concentrations reported at the perimeter ranged from 1-5 ppm and naphthalene was present in the waste materials at concentrations of 1600 ppm before excavation. Neither ATSDR nor EPA have MRL or RfC values presently available(43).
Hemolytic anemia, a condition involving the breakdown of red blood cells, is the primary health concern for humans exposed to naphthalene for either short or long periods of time. Other effects commonly found include nausea, vomiting, diarrhea, kidney damage, jaundice, and liver damage. Cancer has not been seen in humans or animals exposed to naphthalene. The health effects resulting from short or long-term exposure of humans to air containing specific levels of naphthalene are not known. NTP, EPA, and IARC have not evaluated naphthalene for its human carcinogenic potential(43).
Past, present and future exposure to residents and workers to styrene is likely given the known releases during disturbed site conditions, current industrial releases in the area, and available ambient air levels. No MRL or RfC values are currently available(44). Releases are likely under disturbed site conditions and measures should be taken to prevent unacceptable exposures to nearby residents and remediation workers.
Styrene is a chemical mainly used to make rubber and plastics. It often contains other chemicals that give it a sharp, unpleasant smell. The largest amounts of styrene are often found in air, particularly in factories using or producing styrene. It is broken down quickly in air (within one day) when ozone and other substances are present(44).
The most common health problems associated with breathing styrene involve the central nervous system. Workers who breathed large amounts for short periods of time experienced depression, tiredness, muscle weakness, and nausea. People exposed to styrene may also have irritation of the eyes, nose, and throat. Information from limited human and animal studies suggest styrene may possibly be a weak human carcinogen. EPA and IARC consider styrene to be a possible human carcinogen; NTP has not classified styrene for carcinogenicity(44).
Chromium is a naturally occurring element found in rocks, animals, plants, and soil. Present in the environment in several different forms, the most common ones are chromium(0), chromium(III), and chromium (VI). Chromium(III) occurs naturally in the environment but chromium(VI) and chromium(0) are generally produced and released to the environment by industrial processes. Chromium releases can result from burning coal and oil, rubber manufacturing, and vehicular emissions because brake lining and catalytic converters contain chromium. In soil, chromium(VI) is readily converted to chromium(III) by aerobic bacteria in soil containing organic matter(45).
Past, present, and future exposure of residents and workers to chromium is possible near the Del Amo site. Chromium is present in the waste materials/soil and in residential yards. The highest concentration detected in the yard was 514 ppm. ATSDR does not have an oral MRL value for chromium(III) or chromium(VI). EPA's oral RfD for chromium(VI) is 0.005 milligram per kilogram body weight per day (mg/kg/day); for chromium(III), the oral RfD is 1 mg/kg/day(45). Assuming an average 30 year exposure to soil containing either chromium(VI) at 514 ppm with an individual accidentally eating 200 mg/day of contaminated soil during the first six years of life and eating 100 mg/day after age 6 to 30 years, we estimated the daily intake of chromium(VI) to be about 0.002 mg/kg/day which does not exceed the RfD for either chromium(VI). In a maximum exposure scenario, an individual consuming 5000 mg/day of soil for the first six years, 250 mg/day from 6-14 years of age, and 100 mg/day from 15-30 years of age would have an overall daily intake of 0.03 mg/kg/day, which would exceed the RfD and thus noncancer adverse health effects could occur(26). If the chromium were all chromium(III), neither the average nor the maximum exposure scenarios would result in daily intakes exceeding the oral RfD for chromium(III) and adverse health effects would be unlikely(45).
Not much is known about the health effects of chromium(0). Chromium(III) is an essential nutrient needed in small amounts to help the body use sugar, protein, and fat. Seen more in occupational settings, adverse health effects are associated with chromium(VI). Breathing in high levels in air (0.002 mg/m3) of chromium(VI) can cause nose irritations and nose bleeds. Chromium-sensitive people can also experience skin rashes. Long-term exposure to chromium(VI) has been associated with lung cancer in workers exposed to levels 100 to 1,000 times higher than those found in the natural environment (less than 0.0001 mg/m3). EPA, IARC, and NTP consider chromium(VI) to be a known human carcinogen by the inhalation and the oral routes(45).
ATSDR has not developed a Toxicological Profile on 1,1'-biphenyl, also known as diphenyl. It is currently used as a heat transfer agent for some chemical processes and also used to control fungal growth on oranges. Almost insoluble in water, it can exist in soil and be airborne as particulate matter and can also exist as a vapor or gas in air. Occupational exposures usually are higher than those experienced by the general public(46).
Short and long term adverse human health effects have been seen in occupational settings, including respiratory tract and eye irritation, headaches, fatigue, stomach pains, and blood, liver and kidney changes. Although not considered a local skin irritant, 1,1'-biphenyl can be absorbed through the skin(44). Due to unavailable data in either humans or animals, EPA and IARC have not determined its carcinogenicity class(46).
In response to community concerns, the Epidemiological Studies and Surveillance Section (currently the Environmental Health Investigation Branch) within CDHS conducted an epidemiological investigation from 1984 to 1987 in communities near the Del Amo and Montrose hazardous waste sites. The purpose of the study was to evaluate a broad spectrum of health effects, including those specifically raised by community residents, by comparing them to types and rates of effects seen in a similar community not affected by either of the two sites. The study was not designed to answer questions about the health of people who moved away from these neighborhoods, or to assess any possible future health effects that might arise from living near the sites. Reported rates of birth defects, cancer, and mortality derived from the study would not necessarily indicate whether or not the rates were truly elevated.
For the Del Amo site, households within a half mile area south of the site were asked to respond to a household interview survey questionnaire that included questions about health status and symptoms experienced by different family members. About 65% of the households (444 total households) participated in the survey. Responses were compared to those provided by a similar community not living next to a hazardous waste site ("control" community).
Findings from the information reported by the participants from the Del Amo area indicate they did not experience increased rates or unusual patterns of cancer, adverse reproductive health outcomes, or mortality. However, compared to the control area, the rates of several symptoms were higher among residents living near the Del Amo site. These symptoms included skin irritation/rashes and irritation of the eyes, upper respiratory tract, and throat. These symptoms tended to be higher only among people who detected odors in their neighborhoods. The most frequent types of odors reported were sewer, chemical, refinery, dumpsite and factory odors. The study noted that the elevated symptom rates may not have been necessarily caused by either of the hazardous waste sites since other sources of chemical contamination existed (and still exist) in the area, such as petroleum refineries and chemical manufacturing plants. The authors also concluded that some limitations of the study include recall bias, potential bias from low response rate, lack of medical confirmation of reported symptoms, absence of specific exposure data, and inability to draw conclusions about cause and effect(18).
In a related study, adverse reproductive health outcomes and mortality data were examined using vital records available for 1970 to 1984 for people living in census tracts immediately next to the Del Amo site. Results were compared to other census tracts randomly selected throughout Los Angeles County that had similar racial and socioeconomic composition. In reviewing available data from about 22,000 births for rates of low birthweight, fetal and infant death and congenital malformations, the investigator found that congenital malformations appeared to occur more frequently in the census tracts near the Del Amo site as compared to the comparison census tracts. However the investigator also stated that the comparisons were limited by lack of data on specific exposure routes and confounders such as small numbers of cases and incomplete information on gestational age, and that further investigation may be needed. In comparing the results of the vital records review with information reported during the household survey, the investigators noted that the rates of malformations and low birthweight derived from the household survey were very similar in all areas(19).
In reviewing mortality data, the mortality rates were generally similar by area and age. The data appeared to show some slight increase in deaths due to chronic liver disease in women 25-64 years of age and also leukemia as compared to other groups, but no efforts to medically verify the cases were possible. The investigator recommended further studies to verify and clarify these initial findings(19).
Researchers from the University of Southern California School of Medicine also conducted an in-depth review of information collected by the Los Angeles County Cancer Surveillance Program for the period 1972 through 1982, on cancer cases which occurred in the census tracts surrounding the Del Amo site. Their findings indicate no overall increase in cancer rate for adults or children was found in the tracts near the site. In examining the detailed pattern of occurrence of particular cancers, they did not find any pattern suggestive of an association with the site. The researchers added that such a relationship could always be missed because of chance, because too small a proportion of people in the nearby census tracts have been exposed, or, if exposed, have moved away, or because not enough time has elapsed for cancer to occur(20).
Information obtained from the Cancer Surveillance Program for the years 1987, 1988, 1989, and 1990 indicate there were about 30 cancer cases for each year coded to four census tracts located within a one-mile radius of the Del Amo site. The five most common cancers in the overall general population are lung, breast, colorectal, prostate, and bladder. The cases reported by the Cancer Surveillance Program for the four census tracts reflect the normal distribution of cancer cases in the general population. The reported cases appear to reflect the size and age structure of these tracts, but until data are available by race, sex, and age at the tract level, meaningful incidence rates can not be calculated and compared to county, state, or national rates. Additionally, the potentially exposed off-site population is small enough such that no increase in cancer that might be due to site contamination would be able to be detected.
The California Birth Defects Monitoring Program which maintains the State's birth defects registry only recently started including data for Los Angeles County, starting with 1990 births. Therefore, incidence and rate information on birth defects will not be readily available for Los Angeles County(16).
We have addressed each of the community concerns about health as follows:
- If there are unpleasant odors outside, does that mean that the air is unhealthy to breathe?
- Are rashes, breathing problems and headaches caused by chemicals from the site?
- If there is trouble growing fruits or vegetables and if they don't taste right, are they safe to eat?
- Is the water from my tap safe to drink?
- Is it safe for my children to play in the backyard?
- Is it harmful to live next to the waste site?
The unpleasant odors can originate from a number of sources in the area. These sources include garbage dumped in the unpaved Del Amo Boulevard, emissions from the cars and other vehicles in the area and on the nearby freeways, and petroleum refineries and other industries in the area. Several of these industries in the area report air releases of chemicals such as styrene and ethylbenzene which are also associated with Del Amo. In its present undisturbed state, we do not know whether odors are being emitted from the former waste disposal site. During previous excavation activities in the mid-1980s, neighbors complained about odors, especially after rains.
Since the specific sources of the unpleasant odors are not known and we do not have information about overall air quality in the area, it is difficult to discuss the health implications. However, there have been studies demonstrating that exposure to air pollutants, whether from vehicular emissions or industrial releases, can cause damage to the lung tissue and affect breathing capacity.
In past health studies of the community surrounding the site, residents report experiencing skin irritation/rashes as well as irritation of the eyes, upper respiratory tract, and throat. These conditions have been associated to exposure to a number of chemicals and are influenced by a variety of individual factors such as age, health status, and hypersensitivity. Some of the conditions reported are commonly associated with some of the contaminants found at the Del Amo site. However, current information is inadequate for determining whether the contaminants released from the Del Amo site or from other non-site related sources in the area are responsible for the symptoms reported by the residents.
There are a number of factors that could contribute to problems with growing fruits and vegetables and how they taste. Based on available information, it is impossible to determine if fruits and vegetables in residential yards near the site could be impacted by contaminants from the site. Therefore, determination of health effects can not presently be made. Additional sampling of surface soil and outdoor air is required to see if site contaminants have migrated to neighboring yards. Releases from other sources in the area also need to be considered.
Studies have shown that PAHs, and other environmental contaminants associated with the waste disposal area, could be taken up through plant root systems. For instance, root crops with some oil content, such as carrots and onions, can absorb PAHs from the soil. However, little is known about how much contaminants may deposit in plant tissues or the potential toxic effects of environmental contaminants that may be present in fruits and vegetables.
Yes, the shallow groundwater which is contaminated is not used for drinking water and no known exposure to contaminated groundwater from this source has occurred to date. No known drinking water wells have shown any contamination. Seven municipal drinking water wells are located within approximately four miles of the site with the closest one located less than two miles southeast. The drinking water for the area consists of a blend of surface water transported from the Colorado River in Arizona and the Sierra Nevada Mountains in Northern California, and groundwater from the deepest water bearing unit known as the Silverado Aquifer.
Based on the limited soil data for samples taken from 0-1' depths in 1983, PAHs are not detected. As described in the Toxicological Evaluation section, the levels of metals reported in the samples would probably not cause adverse health effects based on ingestion. Data about particulate matter in air are not available. Additional sampling of surface soil and outdoor air is needed to see if site contaminants have migrated to neighboring yards.
Once again there is inadequate information to make a conclusive determination of the health effects of living next to the waste site. During disturbed site conditions, such as drilling or excavation, release of dust and volatile aromatic hydrocarbons, especially benzene, could pose a public health hazard. However, information about extent of releases to ambient or indoor air through soil gas migration during undisturbed site conditions is presently unknown. Additional sampling of surface soil, outdoor, and indoor air is required. Releases from other known sources in the area also need to be considered. Findings from past health studies of the community surrounding the site indicate that residents reported experiencing symptoms that are commonly associated with some of the contaminants found at the site. Presently available information is insufficient to indicate whether the symptoms could be attributed to the site or to other sources in the area such as vehicular emissions or nearby industries.
Based on the information available for review, CDHS and ATSDR conclude that the Del Amo site may pose a public health hazard to nearby residents and workers. Exposure to site-related contaminants found in air and soil, mainly volatile aromatic hydrocarbons and polycyclic aromatic hydrocarbons, probably occurred in the past and may still be occurring to residents and workers in the area through inhalation, ingestion, and possibly skin contact. Past air releases during disturbed site conditions, especially of benzene, were at levels of health concern. The potential for soil gas migration and release to ambient and indoor air also represent a public health concern.
Currently available information does not allow for full determination of exposures to contaminants from the site, as well as other non-site related sources in the area, such as industrial facilities and vehicular emissions. Thus final conclusions of possible health effects cannot presently be made. Findings from past studies indicate residents in the area reported experiencing skin irritation/rashes as well as irritation of the eyes, upper respiratory tract, and throat. Although these symptoms are commonly associated with some of the contaminants found at the Del Amo site, information is insufficient for determining whether the contaminants released from the Del Amo site or other sources in the area are responsible for the symptoms experienced by the residents.
Exposure to contaminated groundwater has not been shown to have occurred to date. However, contamination in the shallow aquifers could move into the deeper aquifers used for drinking water and result in human exposure at levels of health concern if preventive measures are not taken.
Further determination of the extent of contamination in the groundwater underneath residences south of the site and other buildings on top of the site and further characterization of soil gas migration are needed. Indoor air monitoring will be needed to determine actual concentrations which can then be used to assess public health significance of contaminants present.
Additional ambient air monitoring data will be necessary to determine possible exposure point concentrations of site related contaminants in air. Likewise, sampling for particulates in air and house dust, and surface soil sampling in the waste disposal area, other areas of the 280-acre site, the unpaved Del Amo Boulevard, as well as in residential yards is necessary before exposure doses can be determined. Use of mathematical models to determine whether environmental transport models could result in past and future exposures may be helpful. Estimates of exposure doses from all involved pathways will allow a better determination of the public health significance of the exposures.
Prevent/Cease/Reduce Exposure Recommendations
- Improve current public access restrictions to the former waste disposal area through such measures as more secure gates and fences and posting of more signs in both English and Spanish.
- Keep the unpaved Del Amo Boulevard clear of physical hazards.
- Evaluate the potential for soil gas migration underneath homes and businesses near the site.
- Protect persons on and off the site during remediation from exposure to any dusts or vapors that may be released.
- Provide on-site remedial workers with adequate protective equipment and training, in accordance with 29 CFR 1910.120, and follow appropriate National Institute for Occupational Safety and Health and Occupational Safety and Health Administration guidelines.
- Prevent further lateral and vertical migration of groundwater contaminants; maintain continuous monitoring of municipal wells in the area that may be potentially affected.
- Implement institutional controls to prevent future use of contaminated aquifers for drinking water supplies until remediation has reduced contaminant concentrations to below levels of health concern.
- Identify current users of private industrial wells in the area and determine whether water from these wells is contaminated.
- Implement deed and building restrictions to prevent future development on the site until contamination has been reduced to levels below health concern or until levels have been documented to exist at levels below health concern.
Site Characterization Recommendations
- Collect additional groundwater data related to sources of contamination within the 280- acre site in order to supplement groundwater data available from other information sources in order to determine overall extent of groundwater contamination on and off the 280-acre site.
- Assess the nature and extent of the floating layer in the shallow groundwater in the area of the 280-acre site through additional groundwater sampling and soil gas surveys; prevent further migration of the floating layer.
- Conduct indoor air monitoring to assess the migration of soil gas from contaminated soil or groundwater through subsurface soil and into houses and other structures.
- Conduct soil gas survey during rainy and dry periods, in conjunction with additional soil and groundwater sampling for the 280-acre site in order to identify additional sources of contamination and to assess migration of soil gas from known sources, such as the waste disposal area, during rainy and dry periods.
- Collect surface soil (0-3") samples from the 3.7-acre waste disposal area and other undeveloped areas of the 280-acre site, the unpaved Del Amo Boulevard, residential yards, and appropriate background locations for comparison in order to characterize adequately the extent and amount of site contamination that may exist on and off the site. If residential yard soil shows high levels of contaminants, home grown vegetables and fruits and free ranging chickens may also need to be sampled for contaminants.
- Collect surface and subsurface soil (greater than 3") data for the rest of the 280-acre site in order to assess the extent of soil contamination that may exist due to previous storage and handling operations associated with the former rubber manufacturing facilities (for instance storage tanks, pipelines, and waste sumps) or due to other present on-site sources (existing companies and businesses).
- Collect multiple background and site specific ambient air samples, with appropriate meteorological monitoring, to determine overall air quality in the area and to determine site specific air releases. Air samples to document releases from the site in an undisturbed state and a disturbed state (such as during soil borings or excavation activities) should be collected. Analyses should include information for organic and inorganic contaminant concentrations. An air model can also be used to determine dispersion of vapor releases via ambient air.
- Collect data on particulates in indoor and ambient air samples. Use of an appropriate air model to determine fugitive dust emissions from contaminated soil, dispersion, and deposition may also be necessary.
- Collect house dust samples to determine if they contain site related contaminants that could have migrated from the site.
Health Activities Recommendation Panel (HARP) Recommendations
The data and information developed in the Del Amo Preliminary Public Health Assessment have been evaluated by the ATSDR Health Activities Recommendation Panel (HARP) for follow-up health activities. Completed and potential exposure pathways have been identified for nearby residents and workers. However, the available information does not allow for an accurate determination of exposure levels. Releases from other known sources in the area may also be contributing to the environmental contamination in the area and interfere with the estimation of exposure to contaminants released from the Del Amo site. In coordination with other agencies, CDHS will provide ongoing community education in appropriate languages to the communities near the site about possible health effects from site-related contaminants and ways to prevent, cease or reduce exposures.
Available health data, including a health effects investigation and a review of vital statistics and cancer registry information, indicate residents living near the Del Amo site did not appear to experience increased rates or unusual patterns of cancer or death. Residents do report experiencing several irritative symptoms, including skin irritation/rashes, and irritation of the eyes, nose, and throat. Given the fact that more accurate exposure levels cannot be determined due to insufficient environmental data, no further health actions are warranted at this time. When data become available to assess exposure levels, CDHS and ATSDR will reevaluate this site for indicated follow-up health actions.
ATSDR and CDHS will coordinate with the appropriate environmental agencies to develop plans to implement the cease/reduce exposure and site characterization recommendations contained in this preliminary public health assessment. CDHS will also coordinate with other agencies to provide community education in appropriate languages to the communities near the site about possible health effects from site related contaminants and ways to prevent, cease, or reduce exposures.
EPA intends to approach the issue of migration of subsurface gas into homes and other structures in a phased manner, by first taking soil gas samples in the vicinity of several homes and other buildings. In the event that these samples how elevated levels of soil gas, EPA will then consider indoor air monitoring. However, EPA notes that given this site is in an area known to have significant air pollution problems, it may be difficult to distinguish between sources of indoor ambient air contamination.
ATSDR and/or CDHS also plan to review additional data as they become available and determine from the review what further actions are needed to protect public health.
Environmental and Health Effects Assessors:
Diana M. Lee, MPH
Environmental Health Investigation Branch
California Department of Health Services
Community Relations Coordinator:
Jane Riggan, MSW
Impact Assessment, Inc., Consultant to
Environmental Health Investigation Branch
California Department of Health Services
ATSDR Regional Representatives
Regional Services, Region IX
Office of Assistant Administrator
Regional Services, Region IX
Office of Assistant Administrator
Regional Services, Region IX
Office of Assistant Administrator
ATSDR Technical Project Officer
Gail D. Godfrey
Environmental Health Scientist
Division of Health Assessment and Consultation
Remedial Programs Branch, State Programs Section
The Del Amo Facility Site Public Health Assessment has been prepared by the California Department of Health Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health assessment was initiated.
Gail D. Godfrey
Technical Project Officer, SPS, RPB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health assessment and concurs with its findings.
Robert C. Williams, P. E., DEE
Director, DHAC, ATSDR
- U.S. Environmental Protection Agency. Hazard Ranking System Documentation Record, Del Amo, Region IX. 1991.
- Ecology and Environment, Inc. Potentially Responsible Party Search, Del Amo Site. December 1990.
- U.S. Environmental Protection Agency, Region IX. Scoping session, Del Amo Site. October 24, 1991.
- Hargis and Associates, Inc. Preliminary Draft, Remedial Investigation, Montrose Site, Torrance, CA. October 31, 1990.
- Department of Toxic Substances Control, CAL EPA. List of Active Annual Workplan Sites - FY 1991-92. 9/16/91.
- Dames and Moore. Interim Summary of Findings, Del Amo Site Investigation, Los Angeles, California, prepared for Irell & Manella. June 1984.
- Personal communication, Site Manager, Department of Toxic Substances Control. November 7, 1991.
- Letter to Mr. Richard Wilcoxon, Toxic Substances Control Division, from Hekimian & Associates, July 5, 1983.
- Department of Toxic Substances Control. Chronology of Del Amo Site Events, undated.
- Department of Toxic Substances Control. An Analysis of the Environmental Fates and Potential Public Health Impacts of the Residual Soil Contaminants Underlying the Excavation on Lot 37 at the Del Amo Hazardous Waste Site. June 1985.
- Woodward-Clyde Consultants. Task 2 Final Report, Additional Data Acquisition and Interpretation, Del Amo Hazardous Waste Site, Los Angeles, California, Volume 1 of 2. October 2, 1987.
- Dames and Moore. Remedial Investigation Report, Del Amo Site, Los Angeles, California, prepared for G.P. Holdings, Inc., Dow Chemical Company, and Shell Oil Chemical. April 4, 1990.
- Dames and Moore. Feasibility Study Report, Del Amo Site, Los Angeles, California, prepared for G.P. Holdings, Inc., Dow Chemical Company, and Shell Oil Chemical. April 1991.
- Dames and Moore. Revision 3, Baseline Health Risk Characterization, Del Amo Site, Los Angeles, California, prepared for G.P. Holdings, Inc., Dow Chemical Company, and Shell Oil Chemical. April 1991.
- Ecology and Environment, Inc. CERCLA Expanded Site Inspection, Del Amo. June 30, 1989.
- Croen, LA, GM Shaw, NG Jensvold and JA Harris. "Birth defects monitoring in California: a resource for epidemiological research", Pediatric and Perinatal Epidemiology, 5:423-427, 1991.
- Bernstein, L. and RK Ross. Cancer in Los Angeles County, A Portrait of Incidence and Mortality, 1972-1987. 1991.
- Satin, K., Windham, J. Stratton and R. Neutra. Del Amo-Montrose Health Effects Study. California Department Health Services. December 1987.
- Windham, G. Del Amo - Montrose Studies, II. Vital Records Analysis, 1970-84. California Department Health Services. January 26, 1989.
- Mack, TM and RL Pinder. Assessment of Cancer Risk to Persons Residing near Del Amo/Cadillac Fairview Site. University of Southern California. June 1988.
- Department of Toxic Substances Control. Community Relations Plan, Del Amo. December 1985.
- Cooper, CD. The Cadillac Fairview Hazardous Waste Disposal Site. Fall 1983.
- Department of Toxic Substances Control. Del Amo Site Update. (Fact Sheet) September 1986.
- Department of Toxic Substances Control. Del Amo Site: Hazardous Waste Investigation. (Fact Sheet) July 1990.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Polycyclic Aromatic Hydrocarbons. DHHS Publication No. (PHS) TP-90-20. December 1990.
- Agency for Toxic Substances and Disease Registry. Public Health Assessment Guidance Manual. DHHS Publication No. PB92-147164. March 1992.
- Woodward-Clyde Consultants. Del Amo Hazardous Waste Site Remedial Investigation/Feasibility Study: Description of Existing Site Conditions. August 20, 1985.
- Hargis and Associates, Inc. Results of Regional Well Sampling, Montrose Site, Torrance, California - Task 15. November 1, 1990.
- Department of Toxic Substances Control. Del Amo Site, Off-Site Sampling Program. December 20, 1983.
- Department of Health Services. Hazard Materials Laboratory Report HML #8809-8828. December 29, 1983; January 3, 6, 24, 1984.
- Dominguez Water Corporation, personal communication. November 19, 1991.
- 11/7/83 Contact Report, Results of Well and Tap Water Sampling July 7-8, 1983, Del Amo Site.
- Environmental Protection Agency. Exposure Factors Handbook. Washington, DC: Environmental Protection Agency, Office of Health and Environmental Assessment, July 1989; EPA document no. 600/8-89/043.
- South Coast Air Quality Management District. The Magnitude of Ambient Air Toxics Impact from Existing Sources in the South Coast Air Basin. June 1987.
- California Air Resources Board. Preliminary Ambient Air Toxics Data for North Long Beach Station. April 1992.
- Department of Health and Human Services. Sixth Annual Report on Carcinogens - Summary 1991. Research Triangle Park: National Institute of Environmental Health Services.
- World Health Organization/International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans - Supplement 7. 1987.
- Environmental Protection Agency. Integrated Risk Information System. April 1992.
- Agency for Toxic Substances and Disease Registry. Draft Toxicological Profile for Benzene. October 1991.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Ethylbenzene. DHHS Publication No. (PHS) TP 90-15. December 1990.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Toluene. DHHS Publication No. (PHS) PB 90-198904. December 1990.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Xylene. DHHS Publication No. (PHS) TP 90-30. December 1990.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Naphthalene. DHHS Publication No. (PHS) TP 90-18. December 1990.
- Agency for Toxic Substances and Disease Registry. Draft Toxicological Profile for Styrene. DHHS Publication No. (PHS). October 1990.
- Agency for Toxic Substances and Disease Registry. Draft Toxicological Profile for Chromium. DHHS Publication No. (PHS). October 1991.
- Gosselyn RE, RP Smith, and HC Hodge. Clinical Toxicology of Commercial Products. Baltimore: Williams and Wilkins, 1984.
- Shusterman, D, J Lipscomb, R. Neutra, and K Satin. "Symptom prevalence an odor-worry interactions near hazardous waste sites", Environmental Health Perspectives, 94:25-30, 1991.
- Ziem, GE and LL Davidoff. "Illness from chemical 'odors': is the health significance understood?", Archives of Environmental Health, 47:88-90, 1992.
1. Comment: The preliminary Public Health Assessment (PHA) contains misleading information, inappropriate speculation regarding exposure pathways, numerous inaccuracies, and irrelevant comments and anecdotes. The PHA overstates the potential exposure and health risks posed by the Del Amo site and could lead to unjustified concerns about potential health risks among local residents. The document concludes that the "Del Amo site may pose a public health hazard to nearby residents and workers" even though there is a plethora of evidence available regarding this site which establishes that there is no current public health hazard associated with the site.
Response: As with the Del Amo site, CDHS and ATSDR will designate as "preliminary" those public health assessments prepared on sites for which site characterization is incomplete. For the Del Amo PHA, CDHS and ATSDR evaluated data primarily available when the site was initially proposed for inclusion on the NPL in July 1991. Information utilized was obtained from state administrative files, federal agency reports, site visits, and consultations with involved agencies and the public. Designating a public health assessment as preliminary conveys to EPA, the state, and the public that CDHS and ATSDR have conducted the assessment based upon limited data. For sites receiving a preliminary public health assessment, a further public health assessment will be performed, if appropriate, when full environmental characterization is completed, usually in the form of a Remedial Investigation, Feasibility Study, and Baseline Risk Assessment, and provided to ATSDR for consideration.
As defined by EPA in an August 1992 fact sheet on the Del Amo Proposed Superfund Site, the site consists of two study areas. Investigations are currently underway to determine the nature and extent of the 280-acre plant site study area, where the former synthetic rubber manufacturing facility existed. Environmental data for the other study area, referred to as the Del Amo Pit Site and consisting of the 3.7-acre waste disposal area, has been primarily gathered by DTSC since 1985. EPA is currently overseeing the development of the Remedial Investigation, Feasibility Study, and Baseline Risk Assessment for the entire site.
To assist with the development of public health assessments, ATSDR has developed guidance materials, including a Health Assessment Guidance Manual, decision statements, and toxicological profiles. States preparing health assessments under cooperative agreement with ATSDR must utilize the format and include appropriate content as outlined in these guidance materials. All public health assessments undergo a rigorous review by scientists and technical people within CDHS, ATSDR, EPA, and other appropriate agencies before being released for public comment. CDHS and ATSDR welcome additional information from any party who wishes to submit it to us and will make revisions as we deem appropriate.
CDHS and ATSDR have revised the March 1993 Public Comment Draft Public Health Assessment based on public comments supported with adequate documentation. CDHS and ATSDR appreciate the time and effort spent by community members and organizations who commented on the assessment. Many of the comments resulted in revisions that improved the document. In preparation for conducting additional public health assessments, ATSDR will continue to consider information that the public may wish to send us regarding community health issues associated with the Del Amo site. As more complete information is collected and evaluated, the conclusions and recommendations of the public health assessment may be modified or altered to reflect the public health implications of the additional information. In the meantime, the conclusions expressed in the March 1993 Draft Public Health Assessment represent CDHS and ATSDR's position on the information available at the time. CDHS and ATSDR stand by the conclusions presented in the March 1993 document.
2. Comment: The Del Amo site represents a health risk to everyone in the neighborhood. Can something be done to speed up the clean-up process and provide the residents of the area a safe environment?
Response: CDHS and ATSDR agree that the site poses public health concerns for the community and have made recommendations to prevent, cease, or reduce exposures; and to gather data to better characterize exposures. We have shared this concern with EPA, the lead regulatory agency overseeing site investigations and clean-up.
3. Comment: It is quite disquieting to realize the air near my recently purchased home contains known human carcinogens like benzene emanating from the Del Amo site.
Response: Benzene is a common air contaminant and most people are exposed to a small amount of benzene daily. The major sources of benzene exposure include gasoline stations, car exhaust, industrial emissions, and tobacco smoke.
Based on currently available data, it is unclear what the current contribution of emissions or releases from the Del Amo site is to overall air contaminants. As stated in the health assessment, other possible area wide sources of air contaminants like benzene include petroleum pipelines and refineries, and commercial businesses and industries in the area. Since two major freeways exist close by to the Del Amo site and the area experiences a lot of traffic, vehicular emissions in the area also contribute to air contaminants. General ambient air quality in the Los Angeles area tends to be low also.
Data collected in 1984 during past soil boring activities in the waste disposal area show contaminant releases to air at levels of health concern. However data about emissions when the area is undisturbed are limited and questionable. We have included recommendations to prevent/reduce exposures to residents and workers, especially during future activities where there is excavation or uncovering of waste materials or contaminated soils.
4. Comment: The South Coast Air Quality Management District (SCAQMD) Rule 1150 - Excavation of Landfill Sites, contains provisions to reduce the potential of Public Nuisance. Public Nuisance can be identified by odor or dust complaints received from the public in the surrounding areas. The District recommends that specific control measures to reduce odors be addressed, such as the use of vapor suppressants, segregation and storage of contaminated soil in closed containers, or tarping.
Response: CDHS and ATSDR concur with the recommendation and have shared this comment with EPA.
5. Comment: The SCAQMD recommends that sensitive receptors be identified to evaluate those individuals who may be more susceptible to health risks from exposure to toxics. Possible sensitive receptors would include schools, day care centers, hospitals, nursing homes, and retirement communities within three miles of the site.
Response: CDHS and ATSDR concur with the recommendation and have shared this comment with EPA who is overseeing the development of the Baseline Risk Assessment. CDHS has also included demographic information describing data available from the 1990 census.
6. Comment: The SCAQMD recommends that the Public Health Assessment include a discussion of the variability involved in health risks from air toxics due to differences in such parameters as proximity to source, meteorological differences, and non-homogeneity of the population.
7. Comment: The SCAQMD recommends that a worst-case maximally exposed individual be identified for health risks associated with the site. The District also recommends that a hazard indexing or similar approach be used to evaluate the cumulative non-cancer chronic and acute health effects from ambient air concentrations.
Response: CDHS and ATSDR have shared this comment with EPA who is overseeing the development of the Baseline Risk Assessment.
8. Comment: Because the surrounding area includes residential homes, an additional secondary exposure pathway probably exists for exposure to infants from mothers' milk. The SCAQMD recommends inclusion of this pathway in the Public Health Assessment.
Response: CDHS staff spoke with staff from SCAQMD regarding this recommendation on June 17, 1993. Given the uncertainty about the level of exposure people may have to known contaminants and the limited information available regarding the bioavailability and bioaccumulation of specific contaminants, it is not possible to adequately assess this exposure pathway. As additional information does become available, CDHS can review it and decide whether the pathway should be further assessed.
9. Comment: The Community Health Concerns section contains anecdotal comments from the community regarding their health concerns...Detailing these fears in the PHA lends such fears an undeserved air of legitimacy.
Response: As stipulated in ATSDR's Health Assessment Guidance Manual, "community health concerns associated with a site constitute a key data component of the health assessment." Health concerns conveyed by community members are listed in the Community Health Concerns section of the public health assessment. Responses to those concerns are provided in the Community Health Concerns Evaluation. Additional health concerns identified during the public comment period for the public health assessment are also addressed. Thus, the public health assessment serves as a mechanism to respond to community health concerns associated with human exposure to hazardous substances related to a site.
10. Comment: The PHA should include some discussion regarding whether any of the current population resided in the neighborhood during the time the rubber manufacturing facilities were operating and the pits were in use and uncovered (from the 1940s to mid 1960s) and may have been exposed to air releases at that time.
Response: ATSDR and CDHS concur that this information would be useful to include. However, this information is not readily available without doing a detailed community survey. Previous health studies summarized in the public health assessment did not comment on this issue.
11. Comment: The pamphlet issued by CDHS which summarizes the PHA contains a number of inflammatory and unsupported statements which will cause unwarranted community alarm and may incite baseless litigation... The pamphlet also contrasts with the January 1988 issuance of a "Public Announcement regarding Health Study Results for the Del Amo and Montrose Sites." The Public Announcement does not conclude that the contamination at the Del Amo site is a major concern.
Response: CDHS issued the pamphlet in March 1993 to provide health protective information to residents living near the Del Amo site and to announce the start of the public comment period for the public health assessment. Over 600 pamphlets were mailed to residences in the area south of Del Amo Boulevard. CDHS received calls or comments from only five residents. The pamphlet acknowledged there was insufficient information to allow for full determination of exposures to contaminants from the site as well as other non-site related sources in the area. Recommendations were included to advise residents on how to minimize or prevent exposures to hazardous substances. The pamphlet was distributed in both English and Spanish and graphics were used to help "get the message across."
The pamphlet does not contrast with the Public Announcement. The announcement served to summarize the major findings of the health study which is described more fully in the Health Outcome Data Evaluation section of the public health assessment. The announcement summarized that health conditions associated with living near the Del Amo and Montrose sites included sore throats, eye irritation, and skin irritation and that "the lack of adequate offsite monitoring does not permit us to determine whether chemicals from the Del Amo or Montrose sites, or other pollutants common to this industrialized area are the source of the symptoms."
12. Comment: In instances where data suggest that releases or emissions are or may be occurring, confirmatory testing and analyses should be done. We would vigorously oppose, however, any attempt to randomly sample soil across the entire 280-acre proposed site.
Response: In general we concur with the commentator and have shared this comment with EPA.
13. Comment: The original public comment period ran from February 22, 1993, to March 26, 1993. CDHS failed to notify either Cadillac or any of the other local property owners that the draft PHA had been issued. We requested CDHS grant an extension of the comment period until April 23, 1996. CDHS, however, granted an extension until April 16, 1993... The time period allotted was insufficient to adequately review the draft PHA and references and comments. We want to formally request that CDHS and ATSDR promptly notify us of any further activities it plans to undertake at the Del Amo site and to provide us with direct notice of any future public comment periods.
Response: CDHS traditionally notifies the public (including site owners) about the public comment period for a draft PHA through a notice published in local newspapers and through other public media as needed. The notice about the public comment period for the draft PHA on the Del Amo site appeared in the Torrance Daily Breeze newspaper on February 22, 1993. CDHS and ATSDR will continue to coordinate and provide information about site-related activities with a variety of agencies and individuals as we deem appropriate.
14. Comment: ATSDR's method of comparing its derived "health comparison values" to maximum concentrations detected in various media at the site is flawed, leading to misleading conclusions and significant overestimation of risk. This comparison is misleading to the public in the absence of a discussion of real potential for exposure and resulting dose. The PHA should recognize how problematic the use of health comparison values, such as those cited for benzene in ambient air and for metals in soil, becomes in evaluating the contribution, if any, from a hazardous waste site.
Response: As defined in the Environmental Contamination and Other Hazards section of the health assessment, media specific health comparison or guidance values are used to select or screen out contaminants for further evaluation. Comparing maximum concentrations of contaminants to these values helps to ensure that contaminants of concern are not overlooked. The selected contaminants of concern are discussed further in the Pathways Analyses and the Toxicological Evaluation sections of the public health assessment. If adequate data and information are available, an exposure dose can be calculated and compared with appropriate toxicity values. The basis for selecting contaminants of concern and deriving health guidance values and exposure doses, as well as the use of appropriate toxicity values is further detailed in ATSDR's Health Assessment Guidance Manual and chemical specific toxicological profiles.
Neither health guidance nor toxicity values are intended to be used to evaluate whether the contaminant is contributed from a hazardous waste. These values are used to determine whether adverse health effects are possible as a result of exposure to a specific chemical or contaminant.
15. Comment: Although the ambient air pathway may have been a "potential" pathway in the past, there is no reason to believe that such exposure is occurring presently. The ambient air can not be considered a complete pathway.
Response: Although the data are limited, during 1984 soil boring activities when the site was disturbed, a downwind air sample showed an increase of volatile aromatic hydrocarbons as compared to upwind and background samples. During the excavation of pond 1A an increased release of hydrocarbons was also noted and residents complained about odors. Therefore a completed past exposure pathway did exist.
Please see response to comment #3 regarding current and future contribution of emissions or releases from the Del Amo site to overall air contaminants.
16. Comment: The PHA should clearly state that should it be determined in the future that deed and building restrictions are required, those restrictions would apply only to the 3.7- acre waste disposal area, and not the entire 280-acre former plant area of which significant development exists and there is no evidence of significant public health hazard.
Response: EPA is currently overseeing investigations of the 280-acre former plant area. As more complete information is collected and evaluated, the conclusions and recommendations of the public health assessment may be modified or altered to reflect the public health implications of the additional information.
17. Comment: The results of the informal walk-through survey should not be used to attempt to attribute reported health problems to any environmental factor.
Response: CDHS staff walked through the neighborhood nearest the waste disposal area and spoke with people from ten households to identify current health concerns. We addressed these health concerns in the Community Health Concerns Evaluation section of the public health assessment and discussed whether adverse health effects are possible given existing available toxicological and environmental information. Currently available information is inadequate for determining whether the contaminants released from the Del Amo site or from other non-site related sources are responsible for the symptoms reported by the residents.
18. Comment: The discussion of the results of the epidemiology study of local health effects in the PHA overstates the importance of odor detection and irritative health effects. Additional analysis of the data suggested that the reported excess of irritative symptoms might be reasonably explained by heightened odor perception and environmental concern. Shusterman et al (1991) theorized that odor and worry heighten the perception or recall of irritative symptoms.
Response: CDHS does not agree that the discussion of the study results in the Health Outcome Data Evaluation section of the public health assessment overstates the importance of odor detection and irritative health effects. Our discussion noted that the authors of the study (who also co-authored the Shusterman et al article referenced by the commentor) identified limitations to the study, including recall bias where another factor can predispose an individual to remember symptoms. As Shusterman et al state in their article(47), "recall bias is said to occur even when genuine symptoms are being reported, if such symptoms are differentially recalled, depending upon exposure status."
CDHS agree that odor and worry can influence how people might report irritative symptoms. However, as stated by Ziem and Davidoff in a 1992 editorial article(48), "Given the current state of knowledge and the absence of essential research, 'odor-related' complaints cannot ethically be dismissed as nontoxicologic curiosities. Of all nerves, the olfactory nerve has perhaps the closest and most intense contact with the chemical environment. Olfaction helps to protect us from chemical dangers...Whenever there are chemical odors, chemicals are present, and their toxicologic potential should be investigated seriously."
19. Comment: There is no indication that significant concentrations of site-related contaminants have been transported off-site. Off-site sampling of soils from residential yards adjacent to the waste disposal area conducted in 1983 did not indicate the presence of contamination associated with the site. Because no excavation has been performed since 1985 and soil cover has been present across all waste ponds and pits since the late 1960s it is unlikely that significant concentrations of contaminated soil have migrated off-site.
Response: Soil samples taken in 1983 from residential backyards were taken at depths (0-1' and 2'-3') that were not able to adequately characterize surface soil. ATSDR defines surface soil as 0-3". Soil contaminants taken at depths greater than 3" may underestimate the actual concentrations that exist near the soil surface where the greatest exposure probably occurs. In response to the concerns raised about surface soil in residential backyards, EPA will be overseeing a backyard surface soil sampling event scheduled to occur in July 1993.
20. Comment: Soil gas data have been collected recently by Dames and Moore (1993) as part of on-going remedial investigations. Elevated levels of volatile organic compounds were detected in on-site soil gas samples; however, subsequent indoor air monitoring in overlying buildings did not indicate migration of contaminants indoors. Off-site soil gas monitoring, performed by DTSC in 1991 along Del Amo Boulevard did not indicate the presence of contaminants in this area. Therefore, there is no reason to believe that off-site residences have in the past or are presently being exposed to site-related contaminants in indoor air.
Response: The public health assessment identified soil gas migrating into residences and buildings as a potential exposure pathway and included recommendations to conduct soil gas monitoring. CDHS and ATSDR will be able to review the data collected by DTSC and Dames and Moore when it is provided to us and will comment on the public health implications of the data.
21. Comment: Because it is unlikely that there is a route of transport between the contaminated shallow groundwater in the vicinity of the site and the deeper municipal wells more than two miles from the site, the groundwater exposure pathway does not appear to be a potential pathway; therefore, this pathway should be eliminated from consideration.
Response: Based on the information currently available to CDHS and ATSDR, the groundwater pathway is a potential pathway. As new information becomes available, we will review it and make appropriate changes.
22. Comment: The relevance of the TRI data are not clearly explained. It should be noted that TRI data are not applicable to the Del Amo site, and may be representative of background conditions in the general vicinity of the site.
Response: CDHS has added clarifying information about the TRI data reported for the zip code area where the Del Amo site is located.
23. Comment: The values of soil ingestion for young children (200 mg/day) and adults (100 mg/day) are upper bound assumptions that may significantly overestimate exposure and are not generally considered "typical" as indicated in the PHA. In addition, pica is very rare, unusual behavior. It is extremely unlikely that a child would ingest 5,000 mg/day.
Response: The values given above are based primarily on fecal tracer studies and account for ingestion of indoor dust as well as outdoor soil. They are considered representative of long-term average daily ingestion rates. These values are widely used by a number of government and regulatory agencies to provide health conservative estimates of exposure doses for comparison with toxicity values.
As defined in EPA's Exposure Factors Handbook, pica may not occur widely in the general population. However, it appears that it may be more common in populations of low socioeconomic status and certain cultural groups. Sensitive population groups such as young children and pregnant women may engage in pica type practices more frequently, also.
24. Comment: Because site contaminants were not detected in the root zone area of residential backyard soil, there is no reason to believe that plants have experienced significant uptake of contaminants from the soil.
Response: Although polycyclic aromatic hydrocarbons were not detected in the soil samples taken at 0-1' and 2'-3', metals were present. EPA is conducting additional backyard soil sampling to better characterize surface soil conditions. Unfortunately, at present, little is known about plant uptake of contaminants in general.
25. Comment: NAPL layers present in wells P-1 and MW-20 are inaccurately assumed to be "floating layers" on the groundwater surface. Data indicate that NAPL is submerged beneath the groundwater table and essentially immobile.
Response: The information provided so far to ATSDR and CDHS describes the NAPL as a floating layer. We will review additional information as it becomes available.