PUBLIC HEALTH ASSESSMENT
MAYWOOD, LOS ANGELES COUNTY, CALIFORNIA
This report summarizes information that had been collected about the Pemaco Site as of June 1999. At that time, extensive contamination had been found in the soil and groundwater beneath the Pemaco Site. Because of the absence of current on-site activity, no on-site exposure exists. Nevertheless, a substantial probability does exist that contamination has migrated offsite. It is unclear whether the contamination migrated to the west, under the W.W. Henry site, but in all likelihood, off-site exposure has occurred in an undetermined area in the past, or is currently occurring.
At the time of the initial writing of this PHA, substantial data gaps prohibit a complete evaluation of exposure pathways. These data gaps included whether shallow groundwater is present beneath the neighborhood to the south of the site and whether this shallow groundwater is contaminated. It is unknown whether soil gas reaches the homes in the neighborhood to the south of the site or whether contaminated shallow ground water is present beneath the site. It is also unknown whether the surface soil in the yards of the homes in the neighborhood south of the site has been contaminated by wind-blown dust or stack emissions. Finally, it is unknown whether contamination migrated under the W.W. Henry site and moved upward into ambient air.
Since the initial writing of the health assessment, the USEPA has overseen the completion of additional sampling efforts (this data is summarized in the Public Health Recommendations and Action Plan in this document). The additional data suggests that the levels of contaminants detected in the off-site surface soil and soil gas in the residential area south of the site (the yards and the indoor air of 10 to 12 properties) were below levels of health concern. However, the source of the VOCs detected in the indoor soil gas has not been fully characterized and may represent a future potential exposure pathway.
One completed exposure pathway existed in the past- adults and children exposed to emissions from the thermal oxidizer stack installed by the USEPA to destroy soil gas vapors. Now that the thermal oxidizer is shut down, contaminants in the stack emissions cannot be directly measured. And even while it was in operation, the chemicals in the emissions were never directly measured. Also, the target compounds tested did not include dioxins. Nevertheless, these concentrations have been modeled for a series of locations near the site. Thus, CDHS considers these to be completed exposure pathways. The maximum average concentration of emissions from the thermal oxidizer stack occurred at a location approximately 100 meters east-northeast from the site, in a relatively unpopulated area. The concentration of emissions from the thermal oxidizer was also modeled at the Heliotrope Elementary School. For both locations, no significant increase in the lifetime cancer risk occurred, nor were the concentrations of contaminants sufficient to cause non-cancer adverse health effects. Yet, the concentration of chlorinated dibenzofurans and chlorinated dibenzodioxins being emitted from the stack was never measured nor modeled. Thus, CDHS cannot address one of the community's primary concerns, that of the potential for increased adverse health effects due to exposure to these chemicals.
Because the source of VOCs in the indoor air has not been fully characterized, CDHS and ATSDR classify the site as an indeterminate public health hazard. This conclusion is based on the data available to CDHS at the time this PHA was finalized. The conclusions drawn by CDHS are specific to this site only and do not apply to other sites.
The Public Health Recommendations and Action Plan (PHRAP) for this site contains a description of actions at and near the site that have already been taken, are to be taken, or are under consideration by ATSDR and CDHS. The purpose of the PHRAP is to ensure this PHA not only identifies public health hazards, but also provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. CDHS and ATSDR will follow up on this plan to ensure actions are implemented.
- The USEPA worked with the community to determine its concerns about the site and to obtain community input on remediation methods. As a result, USEPA shut down the thermal oxidizer.
- CDHS conducted door-to-door interviews in Spanish with residents of the neighborhood south of the site to determine the level of knowledge about the site and whether those who live in the neighborhood had concerns about the site.
- CDHS evaluated the results of its door-to-door interviews with neighborhood residents to determine the level of knowledge and concern about the Pemaco Site.
- CDHS developed health education materials in Spanish and provided them to the community.
- CDHS staff attended several public meetings and were available to respond to the residents' concerns in Spanish.
- The Remedial Investigation/Feasibility Study (RI/FS) for the site has been completed. USEPA sampled soils near and away from the site, as well as soil vapors on a number of residential houses in the vicinity of the site. USEPA has not uncovered any information that would indicate that the surface soils in the yards of the homes are contaminated by Pemaco products. Again, USEPA still has to review the soil vapor numbers to fully state that there is not a major problem (see next activity for more details).
- To determine the potential for soil gas migration into the homes in the neighborhood south of the site, USEPA implemented a comprehensive shallow groundwater study in the area and sampled soil gas, as well as soil gas in the yards and indoors, for approximately 10-12 families. USEPA requested that the regulatory agency overseeing the W.W. Henry property, the California Regional Water Quality Control Board (RWQCB) order the W.W. Henry PRP's to sample soil vapors and indoor soil vapor during its investigation. During this sampling effort, USEPA collected split samples and, in spring 2002, conducted a second round of soil gas. The levels of acetone in the indoor samples were in the range of 49 -50 ppb, which are well below levels of health concern. USEPA issued a second round because the USEPA toxicologist was concerned that the acetone levels were indicative of an acetone source. USEPA was also concerned that the acetone levels could be a laboratory problem. The second round still showed the presence of acetone in low levels. USEPA has not fully analyzed the results to determine whether or not anything else needs to be done. The product plume from W.W. Henry property and the corner of 59th and Walker (Pemaco-related contamination) are the major sources of the contamination seen in the soil gas numbers and maybe the indoor air.
- USEPA has not sampled home-grown vegetables for any of the neighborhood properties. There are probably less than five families in the immediate area growing vegetables. Based on the soil sampling results and the fact that volatile chemicals do not accumulate in plants, vegetable sampling does not seem indicated.
- USEPA plans to sign a Record of Decision (ROD) for the site in December 2002.
- CDHS will assist USEPA on health educational efforts directed at the community.
- USEPA has tested the water of Maywood MWC#3 for VOC contamination and has not found any levels of concern. USEPA will sample MMWC#3 again when the company stops pumping, in the fall of 2002.
- USEPA has been working with the developer of W.W. Henry property, which is the City of Maywood, to look at risks posed by the properties involved in the proposed park. EPA's contractor has been hired by the City of Maywood to conduct the park risk assessment and EPA's toxicologist has provided technical assistance in the calculation of the park remediation goals.
- CDHS and ATSDR recommend that USEPA characterize the source of the VOCs in the indoor air as a result of soil gas entry. If soil gas is found to be a problem or potential problem in the residential properties, then the USEPA should work with CDHS , the community, and the city of Maywood to identify and implement methods to reduce or eliminate exposure to the soil gas, and to remove the contamination from the groundwater.
Marilyn C. Underwood, Ph.D.
Staff Toxicologist and Chief, Site Assessment Section
Environmental Health Investigations Branch
California Department of Health Services
Community Involvement Coordinators/Health Educators
Community Education and Participation Coordinator
Impact Assessment, Inc.
Consultant to Environmental Health Investigations Branch
California Department of Health Services
Community Education and Participation Coordinator
Impact Assessment, Inc.
Consultant to Environmental Health Investigations Branch
California Department of Health Services
ATSDR Regional Representatives
William Q. Nelson
Regional Representatives, Region IX
Agency for Toxic Substances and Disease Registry
ATSDR Technical Project Officer
Tammie McRae, M.S.
Environmental Health Scientist
Agency for Toxic Substances and Disease Registry
This Public Health Assessment, Pemaco Maywood Site, Maywood, California, was prepared by the California Department of Health Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health assessment was begun.
Tammie McRae, MS
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health assessment and concurs with the findings.
Chief, State Program Section, DHAC, ATSDR
- Herbst J and Genolio T. Expanded site investigation report for Pemaco Maywood, Los Angeles County, Maywood, California. Maywood; 1998 January.
- Gilbert J. Health risk assessment report for Pemaco Maywood, Los Angeles County, Maywood, California. Maywood CA; 1998 July.
- Erler and Kalinowski. Screening human health risk assessment for the W.W. Henry Company Property, Maywood, California. Santa Monica, CA; 2000 February.
- Maywood Mutual Water Company #1. Annual inspection report for Maywood Mutual Water Company #1 for Maywood, California. Maywood, CA; 1997 November.
- Maywood Mutual Water Company #3. Annual inspection report for Maywood Mutual Water Company #3 for Maywood, California. Maywood, CA; October 1997.
- Maywood Mutual Water Company #2. Annual inspection report for Maywood Mutual Water Company #2 for Maywood, California. Maywood, CA; 1999 January.
- California Department of Water Resources, Division of Planning and Local Assistance, Southern District. Watermaster Service in the Central Basin for Los Angeles County; 1998 October.
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- Agency for Toxic Substances and Disease Registry. Toxicological profile for 1,1-dichloroethylene. Atlanta: US Department of Health and Human Services; 1994 May.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for 1,2-dichloroethene. Atlanta: US Department of Health and Human Services; 1996 August.
- Agency for Toxic Substances and Disease Registry. Toxicological Profile for Methylene chloride. Atlanta: US Department of Health and Human Services; 1993 April.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for ethylbenzene. Atlanta: US Department of Health and Human Services; 1997 September.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for 1,2-dibromoethane. Atlanta: US Department of Health and Human Services; 1992 July.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for fuel oils. Atlanta: US Department of Health and Human Services; 1995 May .
- Windholz M, Budavari S, Stroumtsos LY, Fertig MN. The Merck Index. 9th ed, ed. Rahway, NJ: Merck & Co; 1976.
- Agency for Toxic Substances and Disease Registry, Division of Toxicology. Available at: url: http://www.atsdr.cdc.gov/toxfaq.html.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for napthalene. Atlanta: US Department of Health and Human Services; 1995 August.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for styrene. Atlanta: US Department of Health and Human Services; 1992 September.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for tetrachloroethylene. Atlanta: US Department of Health and Human Services; 1997 September.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for toluene. Atlanta: US Department of Health and Human Services; 1994 May.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for 1,1,1-trichloroethane. Atlanta: US Department of Health and Human Services; 1995 August.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for trichloroethylene. Atlanta: US Department of Health and Human Services; 1997 September.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for 1,2,3-trichloropropane. Atlanta: US Department of Health and Human Services; 1992 September.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for vinyl chloride. Atlanta: US Department of Health and Human Services; 1997 October.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for xylenes. Atlanta: US Department of Health and Human Services; 1995 August.
- Office of Environmental Health Hazard Assessment, California Environmental Protection Agency. Cancer Potency Factors List; 1994 December.
- Roy F. Weston, Inc. Emissions test report, Pemaco Maywood Site Maywood, California. West Chester, Pennsylvania; 1998 May.
- Felicia Marcus, Region Administrator USEPA Region IX. Letter to Pete Wilson, Governor of California, notifying him of intent to consider placement of Pemaco Maywood Site on National Priorities List; November 28, 1997.
- Adverse Health Effect:
- A change in body function or the structures of cells that can lead to disease or health problems.
- The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia, that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.
- Background Concentration:
- An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific environment.
- Cancer Risk:
- The potential for exposure to a contaminant to cause cancer in an individual
or population is evaluated by estimating the probability of an individual
developing cancer over a lifetime as the result of the exposure. This approach
is based on the assumption that there are no absolutely "safe" toxicity values
for carcinogens. USEPA has developed cancer slope factors for many carcinogens.
A slope factor is an estimate of a chemical's carcinogenic potency, or 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 slope factor for that carcinogen. Specifically, to obtain risk estimates, the estimated, chronic exposure dose (which is averaged over a lifetime or 70 years) is multiplied by the slope factor for that carcinogen.
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. In other words, in a million people it is expected that 250,000 individuals would get cancer from a variety of causes. If we say that there is a "one-in-a-million" excess cancer risk from a given exposure to a contaminant, we mean that if one million people are exposed to a carcinogen at a certain concentration over their lifetime, then one cancer above the background chance, or the 250,000th 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 calculated, and, in fact, may be zero.
- See Comprehensive Environmental Response, Compensation, and Liability Act.
- Completed Exposure Pathway:
- See Exposure Pathway.
- Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):
- CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.
- A belief or worry that chemicals in the environment might cause harm to people.
- How much or the amount of a substance present in a certain amount of soil, water, air, or food.
- See Environmental Contaminant.
- Dermal Contact:
- A chemical getting onto your skin. (See Route of Exposure.)
- The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as the amount of substance(s) per body weight per day.
- The relationship between the amount of exposure (dose) and the change in body function or health that result.
- The amount of time (days, months, years) that a person is exposed to a chemical.
- Environmental Contaminant:
- A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Concentration, or what would be expected.
- Environmental Media:
- Usually refers to the air, water, and soil in which chemicals of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.
- Environmental Media Evaluation Guide (EMEG):
- EMEGs are media specific values developed by ATSDR to serve as an aid in selecting environmental contaminants that need to be further evaluated for potential health impacts. EMEGs are based on non-carcinogenic endpoints and do not consider carcinogenic effects. EMEGs are based on the MRLs.
- Coming into contact with a chemical substance. (For the three ways people can come in contact with substances, see Route of Exposure.)
- Exposure Assessment:
- The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.
- Exposure Pathway:
- A description of the way that a chemical moves from its source (where it
began) to where and how people can come into contact with (or get exposed
to) the chemical. ATSDR defines an exposure pathway as having five parts:
- A Source of Contamination
- Environmental Media and Transport Mechanism
- Point of Exposure
- Route of Exposure
- Receptor Population
When all five parts of an exposure pathway are present, it is called a Completed Exposure Pathway.
- Water beneath the earth's surface that flows through soil and rock openings, and often serves as a source of drinking water.
- Hazard Index:
- The Hazard Index is a ration of the estimated dose divided by the reference dose (or other non-cancer health comparison value. If the estimated daily dose is less than the reference dose (or other non-cancer health comparison value) (i.e., the Hazard Index is less than 1.0), people are not likely to be harmed. However, if the Hazard Index is above 1.0, there is potential for concern.
- Hazardous Waste:
- Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.
- Maximum Contaminant Level (MCL):
- The USEPA has issued drinking water standards, or MCLs, for more than 80 contaminants in drinking water. The MCLs are set based on known or anticipated adverse human health effects (which also account for sensitive subgroups, such as, children, pregnant women, the elderly, etc.), the ability of various technologies to remove the contaminant, their effectiveness, and cost of treatment. For cancer risk, USEPA generally sets the MCLs at concentrations that will limit an individual risk of cancer from a contaminant to between 1 in 10,000 (low increased excess risk) to 1 in 1,000,000 (no apparent increased excess risk) over a lifetime. As for non-cancer effects, USEPA estimates an exposure concentration below which no adverse health effects are expected to occur.
- Non-Cancer Evaluation, ATSDR's Minimal Risk Level (MRL), and USEPA's Reference Dose (RfD) and Reference Concentration (RfC):
- The MRL, RfD, and RfC are estimates of daily exposure to the human population
(including sensitive subgroups), below which non-cancer adverse health effects
are unlikely to occur. The MRL, RfD, and RfC only consider non-cancer effects.
Because they are based only on information currently available, some uncertainty
is always associated with the MRL , RfD, and RfC. "Safety" factors are used
to account for the uncertainty in our knowledge about their danger. The greater
the uncertainty, the greater the "safety" factor and the lower the MRL, RfD,
When there is adequate information from animal or human studies, MRLs and RfDs are developed for the ingestion exposure pathway, whereas RfCs are developed for the inhalation exposure pathway. A MRL, RfD, or RfC is an estimate of daily human exposure to a substance that is likely to be without an appreciable risk of adverse (non-carcinogenic) health effects over a specified duration of exposure. No toxicity values exist for exposure by skin contact. Separate non-cancer toxicity values are also developed for different durations of exposure. ATSDR develops MRLs are acute exposures (less than 14 days), intermediate exposures (from 15 to 364 days), and for chronic exposures (greater than 1 year). USEPA develops RfDs and RfCs for acute exposures (less than 14 days), subchronic exposures (from 2 weeks to 7 years), and chronic exposures (greater than 7 years). Both the MRL and RfD for ingestion are expressed in units of milligrams of contaminant per kilograms body weight per day (mg/kg/day). The RfC for inhalation is expressed in units of mg/m3.
- Non-Cancer and Cancer Evaluations USEPA's Preliminary Remediation Goals (PRGs):
- PRGs are developed by the USEPA to estimate contaminant concentrations in the environmental media (soil, air, and water), both in residential and industrial settings, that are protective of humans, including sensitive groups, over a lifetime. PRGs were developed for both industrial and residential settings because of the different exposure parameters, such as different exposure time frames (e.g., industrial setting: workers are exposed for 8 hours/day, 5 days/week vs. residential setting: families are exposed 24 hours/day, 7 days/week; and different "human" exposure points such as industrial setting: healthy adult males vs. residential setting: males, females, young children, and infants), etc. Media concentrations less than the PRGs are unlikely to pose a health threat; whereas concentrations exceeding a PRG do not automatically determine that a health threat exists, but suggest that further evaluation is necessary.
- The National Priorities List (which is part of Superfund). A list kept by the USEPA of the most serious, uncontrolled, or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.
- Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.
- A line or column of air or water containing chemicals moving from the source to areas further away. A plume can be a column or clouds of smoke from a chimney or contaminated underground water sources or contaminated surface water (such as lakes, ponds, and streams).
- Point of Exposure:
- The place where someone can come into contact with a contaminated environmental medium (air, water, food, or soil). Examples: the area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.
- A group of people living in a certain area; or the number of people in a certain area.
- Potentially Responsible Party. A company, government, or person that is responsible for causing the pollution at a hazardous waste site. PRP's are expected to help pay for the clean up of a site.
- Public Health Assessment(s):
- See PHA.
- Public Health Hazard:
- The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.
- Public Health Hazard Criteria:
- PHA categories given to a site which tell whether people could be harmed
by conditions present at the site. Each are defined in the Glossary. The categories
- Urgent Public Health Hazard
- Public Health Hazard
- Indeterminate Public Health Hazard
- No Apparent Public Health Hazard
- No Public Health Hazard
- Reference Dose Media Evaluation Guide (RMEG):
- RMEGs are media specific values developed by USEPA to serve as an aid in selecting environmental contaminants that need to be further evaluated for potential health impacts. RMEGs are based on non-carcinogenic end-points and do not consider carcinogenic effects. RMEGs are based on the USEPA RfDs.
- Route of Exposure:
- The way a chemical can get into a person's body. There are three exposure
- Breathing (also called inhalation);
- Eating or drinking (also called ingestion); and
- Getting something on the skin (also called dermal contact).
- Semivolatile Organic Compound (SVOC):
- A chemical compound that partially evaporates or changes from liquid to gas readily at room temperature.
- Source (of Contamination):
- The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.
- Special Populations:
- People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.
- Superfund Site:
- See NPL.
- Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.
- The study of the harmful effects of chemicals on humans or animals.
- Urgent Public Health Hazard:
- This category is used in ATSDR's PHA documents for sites that have certain physical features or evidence of short-term (less than 1 year) site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.
- Volatile Organic Compound (VOC):
- A chemical compound that evaporates (volatilizes) or changes from liquid to gas readily at room temperature.