PUBLIC HEALTH ASSESSMENT
SHERWIN WILLIAMS
EMERYVILLE, ALAMEDA COUNTY, CALIFORNIA
A public health assessment is the evaluation of data and information on the release of hazardous substances into the environment in order to assess possible impact on the health of communities located near the site. The public health assessment is the basis for recommendations to help affected communities reduce or eliminate exposure to these hazardous substances, and to identify studies or health activities, such as community health education, that assist communities in addressing potential health effects. A public health assessment differs from a risk assessment, which is prepared by the U.S. Environmental Protection Agency and other regulatory environmental agencies. A risk assessment is a quantitative, numeric estimate of public health impacts of exposure to contamination in order to support site specific decisions on the need for cleanup and remediation. A public health assessment is more qualitative and descriptive in nature, and is used to provide affected communities with information on the public health implications of a specific site and to make recommendations regarding ways to reduce or eliminate exposure.
The objectives of this public health assessment are to: (1) review pre-cleanup surface soil data from the areas near the 45th Street Artists' Cooperative in order to evaluate possible adverse health effects to residents from exposure to arsenic and lead in these soils, and (2) make recommendations regarding future public health activities at the Coop. This public health assessment will evaluate only the potential health impact caused by incidental ingestion of contaminated soils. It will not address the impact of inhalation of contaminated soils. The impact of arsenic and lead contamination in individual residents' studios will be the subject of a future document.
The Sherwin-Williams facility is located on Sherwin Avenue in Emeryville, California. Emeryville is located on the eastern side of the San Francisco Bay between Berkeley to the north, and Oakland to the east and south. The facility has been in operation since the early 1900's as a coatings manufacturer. In addition, the facility produced lead arsenate pesticides from the 1920's to the 1940's. It currently manufactures water-based paints and other coatings.
In 1987, the paint manufacturing process was converted from oil-based products to water-based products. During this change, oil and solvent storage facilities were dismantled and Sherwin-Williams discovered groundwater and soil contamination. Several site investigations have determined that the primary contaminants on the site include volatile organic chemicals, semi-volatile organic chemicals, petroleum hydrocarbons, and metals (primarily arsenic and lead). Currently, the areas with contaminated soils have been covered with an asphalt cap, and the area with the most heavily contaminated groundwater has been enclosed with a slurry wall to reduce or prevent the migration of contaminated groundwater. A groundwater extraction and treatment system is operating with the goal of creating an inward hydraulic gradient across the slurry wall, thereby preventing arsenic and lead contaminated groundwater from migrating off site.
Directly across Horton Street from the Sherwin-Williams facility/site, at the corner of Horton and 45th Streets, is the 45th Street Artists' Cooperative (the Coop). The Coop facility was converted from a former industrial facility to live/work artist studios in 1974. Until about 1969, the Coop building was a part of a petrochemical research and development facility. The Coop consists of 32 studios, offices, and other facilities in a main facility (45th Street Building), and 24 additional studios in a second building (the Annex) located across the street to the south of the 45th Street building. Another housing development, the Horton Street Lofts, is also located to the south of the 45th Street Building, adjacent to the Coop Annex.
In the Spring of 1997, during construction activities on nearby properties, high levels of arsenic and lead were discovered in the soils on the site. This lead to an additional investigation which ultimately located high levels of arsenic and lead on the Coop property and in flower beds adjacent to the 45th Street Building and the Annex/Horton Street Lofts. Four general areas were identified and investigated: a Patio Area located on the northeast corner of the Coop property; a Garden Area located on the northwest corner of the Coop property and immediately across Horton Street from Sherwin-Williams; flower beds adjacent to the 45th Street building and directly across Horton Street from Shewin-Williams; and flower beds adjacent to the Annex/Horton Street Lofts on Horton Street and just down the street from Sherwin-Williams.
Very high levels of arsenic and lead, levels of potential health concern for both children and adults, were discovered in the flower beds adjacent to the 45th Street building. Arsenic and lead were also discovered in the flower beds adjacent to the Annex/Horton Street Lofts, and in the Garden Area on the Coop property at levels of potential health concern, though at levels lower than those found in the other flower bed. The Patio Area contained levels of arsenic and lead that were comparable to naturally occurring background levels. By the Fall of 1997, the flower beds and the Garden Area had been cleaned up. The Patio Area was considered to be uncontaminated and was not cleaned up.
CDHS has concluded, assuming a worst-case scenario of daily exposure to the most contaminated soils for a period of greater than one year, that past levels of arsenic and lead on and near the Coop property posed a public health hazard for both non-cancer and cancer health effects. However, with the cleanup of the Garden Area on the Coop property and the flower beds along Horton Street adjacent to the 45th Street building and the Coop Annex/Horton Street Lofts, there is no longer a public health threat due to exposure to contaminants from these areas.
BACKGROUND AND STATEMENT OF ISSUES
The California Department of Health Services (CDHS) Environmental Health Investigations Branch (EHIB), under cooperative agreement with the U.S. Agency for Toxic Substances and Disease Registry (ATSDR), evaluated the results of soil samples collected in and near the property of the 45th Street Artists' Cooperative in Emeryville, California. The residents of the Cooperative were concerned about the possible presence of contamination on Coop property, because it is located directly across the street from a Sherwin-Williams coating manufacturing facility. The Sherwin-Williams facility has been undergoing investigation and cleanup following the discovery of lead and arsenic on adjacent properties. This contamination has been traced back to the Sherwin-Williams facility which, in the past, was used to manufacture lead arsenate pesticide.
Those areas of the 45th Street Artists' Coop with the highest levels of contamination have been cleaned up. Therefore, this Health Assessment will focus on past exposures to contamination on the Coop property.
The Sherwin-Williams Site is located at 1450 Sherwin Avenue at Horton Street in Emeryville, Alameda County, California. Emeryville is located on the east side of the San Francisco Bay, between the cities of Berkeley to the north and Oakland to the east and south (see Figure 1). Emeryville was primarily an industrial city until the 1970s, when many of the industrial and manufacturing facilities left the city. Emeryville is currently involved with extensive redevelopment efforts, with the goal of converting some of these old sites to light industrial, commercial, or residential use (1). The section of Emeryville, near the Sherwin-Williams site, is a light industrial/commercial area, with several artist live/work projects located in the area.
The Sherwin-Williams site is approximately 10 acres in size, and is bounded by Horton Street to the east, Temescal Creek and the Rifkin Property to the north, railroad tracks to the west, and Sherwin Avenue to the south. The Sherwin-Williams Facility is located on the Site at 1450 Sherwin Avenue (see Figure 2) (1). There are between 100 and 125 employees at the Sherwin-Williams Facility who work in three shifts.
The Sherwin-Williams facility has been in operation since the early 1900's as a coating manufacturing facility, and during the 1920's to the 1940's, it also produced lead arsenate pesticides. During the conversion of the plant in 1987 from the production of oil-based paints to water-based paints, contamination was discovered on site. Various investigations at the Sherwin-Willliams facility, under oversight of the San Francisco Bay Regional Water Quality Control Board (RWQCB), have revealed contamination in the soil and groundwater of the Sherwin-Williams property by volatile organic chemicals, semi-volatile organic chemicals, petroleum hydrocarbons, and metals, primarily lead and arsenic.
Contamination has also been found on other nearby properties. This includes volatile organic chemicals, total petroleum hydrocarbons, and arsenic contamination in the soil and shallow ground water of the southern Rifkin Property, and arsenic and lead contamination in the soils along both sides of Horton Street (see Figure 2). The discovery of this contamination on Horton Street prompted the Emeryville City Council to take action by requesting biological monitoring of the Coop residents (1). Sherwin-Williams agreed to pay for blood and urine testing for arsenic and lead for interested area residents. Approximately 25 individuals were tested at a nearby medical facility. A review of the results of this testing showed no elevated levels of lead or arsenic. The contaminated soil in the flower beds along Horton Street and in one area on the Coop property were removed under an emergency cleanup order.
To minimize or eliminate the migration of contamination from its property until permanent remedial measures could be implemented, Sherwin-Williams installed several interim remedial measures. These included building a slurry wall (installed November 1994) and implementing a pump-and-treat system within the boundary of the slurry wall to create and inward hydraulic gradient, and to remove organic and arsenic contamination from the ground water. In addition, a cement/asphalt cap was constructed to prevent contact with contaminated soils, to prevent storm water from mixing with contaminated soil, and to prevent wind erosion of contaminated soil. Other measures have been put into place to prevent contaminated ground water and runoff from storm drains from reaching nearby Temescal Creek.
The 45th street Artists' Cooperative (referred to hereafter as the Coop) is located at 1420 45th Street in Emeryville, Alameda County, California, directly across Horton Street from the Sherwin-Williams Facility, at the corner of Horton and 45th Streets. It is bounded on the north by property owned by the Chiron Corporation, on the east by a Pacific Gas and Electric facility, on the west by Horton Street, and on the south by 45th Street (see Figure 2). The Coop is an artist owned and managed facility that was founded in 1974. The building was formerly a Shell Oil research facility. Coop residents share community outdoor garden space and other facilities (1).
Another live-work project called the Horton Street Lofts is located across 45th Street from the Coop and adjacent to the Coop Annex (1). The Horton Street Lofts were converted from a lumber warehouse to condominiums in the early 1990s. The flower beds along Horton Street adjacent to the Horton Street Lofts and the Coop Annex were also sampled at the same time as the Coop property, and was found to be contaminated as well. These flower beds were cleaned up at the same time as the Coop flower beds.
CDHS became involved with this site in April 1997 when it was asked by Mara Feeney and Associates to attend a visit to the Coop. Arsenic and lead had been discovered on both sides of Horton Street next to the Sherwin-Williams facility, and Coop residents were concerned about the possible presence of contamination on their property. Representatives of the Coop, Sherwin-Williams, the city of Emeryville, SECOR (an engineering firm), and Levine-Fricki-Recon (LFR, an engineering firm), and Mara Feeney and Associates (private community relations consultant) also toured the Coop property. The group made suggestions as to locations at which to collect samples for additional lead and arsenic sampling. This site visit occurred on April 3, 1997. LFR sampled the site a few days later.
Based upon 1990 Census data, the total population of the City of Emeryville is 5740. The population is approximately 50.4% female and 49.6% male. The racial makeup of the city is: 50.7% white, 22.4% African-American, 18.1% Asian/Pacific Islander, 8.3% Hispanic, and < 1% Native American. The age distribution is: 0 - 4 years old, 4.4%; 5 - 9 years old, 2.8%; 10 - 13 years old, 4.1%; 14 - 17 years old, 2.5%; 18 - 24 years old, 11.6%; 25 - 34 years old, 26.7%; 35 - 44 years old, 19.4%; 45 - 54 years old, 10.2%; 55 - 59 years old, 4.1%; 60 - 64 years old, 5.4%; 65 - 74 years old, 6.7; 75 - 84 years old, 2.1%; and greater than 85 years old, 0.7%.
According to the resident manager, the Coop has a total of 56 studios, with 32 studios, the office, and laundry facilities located at the 45th Street Building, and 24 studios at the Annex. During the Summer of 1997 when Horton Street was being remediated, the Coop had about 80 members, including six children. Four children lived at the 45th Street Building, and two children lived at the Annex. One child at the 45th Street Building was two and a half years old, two were six years old, and one was six and one half years old. Information on the children in the Annex was not available.
Currently, 34 adults live at the 45th Street Building, and eight other adults use their units for work only. Three children and one teenager also live at the 45th Street Building. Twenty-seven adults live at the Coop Annex, and five adults use their units for work only. Two children and one teenager also live at the Annex. Most Coop residents range in age from 35 - 55 years old.
There are 15 units in the Horton Street Lofts, 11 of which are used as residences, and four of which are used during the day as art studios or other businesses. Roughly 18 people, including two children, live in the 11 residential units, and 17 people work in the other four units (1).
Another housing development is currently being constructed in the vicinity. The Emeryville Warehouse project is located directly south of the Sherwin-Williams site across Sherwin Avenue, and west of the Horton Street Lofts/Coop Annex across Horton Street. This building was formerly a warehouse for Sears, Roebuck, and Company. The development will consist of 125 units, which is expected to be completed in December 1998. Based upon an Emeryville average of 1.7 people per household, approximately 213 people are expected to live in this development (6).
CDHS is not aware of any historical data regarding possible adverse health effects due to exposure to lead and arsenic in the flower beds along Horton Street adjacent to the Coop, or on the Coop property. However, as was mentioned above, Sherwin-Williams offered to pay for blood and urine testing for arsenic and lead to interested Coop residents following discovery of the contamination in 1997. Approximately 25 Coop residents took advantage of blood and urine testing. CDHS was provided with the results of this testing with all personal identifiers removed. A brief review of these results did not reveal any elevated levels of arsenic or lead. However, because the data were provided with no personal identifiers, CDHS does not know the age, sex of the residents who were tested, nor the unit in which they live.
Historically, the residents across the street from the Sherwin Williams plant have had little knowledge about the remediation activities occurring at the site. From 1988 until March 1997, Sherwin Williams conducted a voluntary investigation at the site under RWQCB oversight. After significant lead and arsenic contamination was discovered along Horton Street in March, 1997, RWQCB issued a Cleanup and Abatement Order (CAO) and the resultant sampling conducted by Sherwin Williams revealed exceedingly high levels of lead and arsenic in areas of exposed soil along Horton Street. In response to this finding, the Emeryville City Council requested immediate "health screening". Because state and federal agencies could not perform biological testing immediately, Sherwin Williams agreed to provide lead and arsenic testing for the area residents. About 25 residents volunteered to be tested and all the results appeared to be within normal limits.
Soil along Horton Street was removed and sidewalks were replaced from June through September of 1997. Some of the residents in the 45th Artists' Cooperative were disturbed by the way the soil removal was carried out and felt that their lives were unduly disrupted. They expressed many of their concerns in the Public Participation Plan, which was another requirement of the March 1997 CAO.
When the State's Site Designation Committee designated the RWQCB to be the lead agency for the cleanup at the Sherwin-Williams site, one requirement imposed by the Committee was the formation of a Consultative Work Group (CWG). The CWG is a committee with the responsibility to oversee remediation activities at the site, review all documents produced to ensure that they adequately address community concerns, and to provide a forum for public participation. Its members include Sherwin-Williams and its contractors, RWQCB; Chiron Corporation and its contractors (Chiron property is located adjacent to the Sherwin-Williams site and has been impacted by contamination on the site), California Department of Toxic Substances Control, California Department of Health Services, the City of Emeryville, Mara Feeney and Associates, California Environmental Research Group, and the 45th Street Artists' Cooperative. Other neighborhood groups had been asked to participate, but thus far have declined to do so. The CWG met for the first time in January 1998.
Many of the residents were concerned about whether they could trust Sherwin Williams to clean up the site without harming the neighborhood. They were upset that they had not been informed adequately in the past about the interim remedial measures such as the slurry wall and were particularly unhappy with the way the emergency soil removal had been carried out in the summer of 1997. Residents complained about excessive noise, dust and debris, lack of access to units, heat and poor ventilation. Several of the artists felt that the removal had negatively impacted their businesses. Residents stated that they had totally inadequate information before the removal, and that there were no established lines of communication for them to voice complaints during the removal. The outcome is that the residents are extremely leery about any future remediation and do not trust that it will be carried out in a nondisruptive and safe manner.
Many of the Coop residents have lived in the area for ten to fifteen years and are concerned about the future health effects that may results from the past exposure to the site contaminants. Several of the artists feel particularly vulnerable because site exposures could potentially compound their long-term occupational exposures. Because of the problems with last spring's emergency removal, residents are concerned about future excavations and soil removal and the affect it could have on their health.
Identification of Contaminants of Concern
In order to assess the potential adverse health effects of environmental contamination on a nearby population, one must first identify those environmental contaminants which are present at a high enough concentration to possibly cause adverse health effects. Those contaminants so identified are called contaminants of concern, and are identified as follows.
Comparison to Screening Values
The concentration of the contaminant in a specific medium (soil, air, and water) is compared to a screening value for that contaminant in that medium. This screening value is the concentration of a specific chemical in a specific medium (soil, air, water) at or below which a person could be exposed to that chemical without the expectation of adverse health effects occurring. These values are calculated using very conservative assumptions regarding the body weight and ingestion rate of the receptor population, so that if the concentration of the contaminant is below the screening value, one should feel confident that adverse health effects should not occur. If the concentration of the contaminant exceeds the screening value, then it is called a contaminant of concern. However, adverse health effects do not automatically occur if the concentration of a chemical exceeds its comparison value. The chemical must be further evaluated on an individual basis to determine the likelihood of exposure and the possibility of adverse health effects.
ATSDR uses screening values for both cancer and noncancer adverse health effects. These are described below.
Screening Values for Non-Cancer Adverse Health Effects
ATSDR uses several types of screening values to evaluate contaminants of concern for their potential to cause non-cancer adverse health effects. The primary screening value that ATSDR uses is called an Environmental Media Evaluation Guide (EMEG). An EMEG is a concentration of a chemical in soil, air, or water, above which a person might experience adverse health effects if exposed to that chemical. EMEGs are based on a Minimal Risk Level (MRL), which is the daily dose (mg/kg/day) of a chemical to which a person could be exposed without experiencing adverse health effects. MRLs, in turn, are derived most often from animal exposure studies, though some are calculated from human exposure studies. MRLs may be calculated for different lengths of exposure (acute, up to 14 days; intermediate, 15 to 364 days, and chronic, 365 and more), and for different routes of exposure (inhalation or ingestion).
If there is no MRL or other similar value for a chemical, then other values are used. Of the four chemicals measured in these samples, lead does not have an MRL. CDHS opted to use the California Environmental Protection Agency Preliminary Remediation Goal (PRG) for lead as its screening value. PRGs are used as initial cleanup goals for a specific chemical in soil for a given land use (industrial, residential), as well as screening values. This PRG is calculated using the California Department of Toxic Substances Control Lead Risk Assessment Spreadsheet (6).
EMEGs are calculated for both children and adult, based upon default values of body weight, amount of soil incidentally ingested, and amount of water drunk each day. However, there are some children who exhibit a type of behavior called pica behavior. Children who exhibit pica behavior have a propensity to eat non-food items such as soil, sand, clay, ashes, and other similar substances. The average amount of soil eaten by pica children is estimated at 5000 mg/day, as opposed to the average of 200 mg/day consumed by a child who does not exhibit pica behavior, and this increased amount puts them at greater risk for adverse health effects (the EMEG is correspondingly lower for pica children). If any of the children who live at the Coop exhibited pica behavior during the time the contaminated soils were in place, then the potential for adverse health effects becomes much higher.
Screening Values for Carcinogenic Adverse Health Effects
The screening value that ATSDR uses to identify carcinogenic contaminants of concern is called a Cancer Risk Evaluation Guide (CREG). A CREG is the concentration of a chemical in a specific medium (air, soil, water) that would be expected to cause a greater than 1 x 10-6 increase in the lifetime cancer risk if ingested.
When considering the increased lifetime cancer risk, one must understand that this value represents the expected increase in the number of cases of cancer, over and above the normal background rate of cancer, which ranges from 25% - 35%. In an average population of 1,000,000 people, approximately 250,000 of those people (assuming a 25% background rate) will develop cancer during their lifetime due to various factors. An increased lifetime cancer risk of 1 x 10-6 means that in that same population of 1,000,000 people, 250,001 will develop cancer at some point in their lifetimes, with the extra one case being due to the specific chemical exposure being evaluated.
On-Site Contamination (Sherwin-Williams Site)
The on-site contamination at the Sherwin-Williams site includes volatile organic compounds, semivolatile organic compounds, petroleum hydrocarbons, and metals, primarily arsenic and lead, and is found in both soil and ground water. However, this site is undergoing remediation under the direction of the San Francisco Bay Area Regional Water Quality Control Board. Sherwin-Williams has installed interim remedial measures to prevent or retard the migration of contamination off-site. These measures include the installation of a slurry wall and a cement/asphalt cap and storm water collection system. The slurry wall (see Figure 2) was installed in November 1994 to prevent or retard migration of contaminated ground water. The cap was installed in September 1995 to prevent contact with contaminated soils, to prevent wind erosion of contaminated soils, and to prevent rainwater from mixing with contaminated soil and groundwater. While the groundwater is contaminated, it is not a possible exposure pathway because area residents use municipal water, not local well water. Thus, the contamination in the soil and groundwater on the Sherwin-Williams site itself does not pose a direct threat to the health and safety of area residents or of Sherwin-Williams employees.
Off-Site Contamination (Coop Property)
In early April 1997, Sherwin-Williams sampled 50 locations on Coop property, in the flower beds located along Horton Street adjacent to the Coop building, and along Horton Street adjacent to the Horton Street Lofts and the Coop Annex. Each location was sampled at up to three depths, ranging from 0.25 feet to 5 feet, and each sample was analyzed for arsenic, lead, zinc, and cadmium (see Figures 3,4) (2). In general, the concentration of contaminants in these soils decreased with increasing depth. This suggests that the arsenic, lead, zinc, and cadmium in the upper levels of the soil are probably contaminants which have been deposited on the ground surface. CDHS evaluated soil samples collected at 0.25 (three inches) and 0.5 feet (six inches). Soil samples deeper than this were not evaluated because it is not likely that people will be routinely exposed to soils this deep. Figure 4 shows the sample number for the sampling locations that CDHS evaluated.
CDHS divided the Coop property and the flower beds along Horton Street into four areas. These were: the Patio Area (northeast area of the Coop property, including the central planter and flower pots, see unshaded sampling locations, Figure 5); the Garden Area (beside the Horton Street driveway, see shaded area, Figure 5); the flower beds along Horton Street adjacent to the Coop (immediately north and south of the Horton Street driveway, see unshaded sampling locations, Figure 6); and the flower bed along Horton Street adjacent to the Coop Annex/Horton Street Lofts (south of 45th Street and directly in front of the Horton Street Lofts and the Coop Annex, see shaded sampling locations, Figure 6). The flower beds along Horton Street adjacent to the Coop and the Annex are actually property of the City of Emeryville. However, Coop residents worked in these flower beds, so the flower beds are included in this discussion of contamination on the Coop property.
By September 1997, Sherwin-Williams had cleaned up the flower beds along Horton Street adjacent to the 45th Street building, and the flower bed adjacent to the Coop Annex/Horton Street Lofts buildings. The Garden Area on the Coop property was also cleaned up. Therefore, any discussion of exposure to contaminated soils refers to past exposures.
Tables 5 - 8 provide the sample number, depth, and the concentration of arsenic, lead, zinc, and cadmium for those samples evaluated by CDHS. These tables also show the geometric mean and maximum concentration of each contaminant, along with their respective screening values and background concentrations in the environment. These tables are summarized below.
The concentration of arsenic in the Garden Area of the Coop ranged from a minimum concentration of 2.9 ppm to a maximum concentration of 21 ppm, with a geometric mean concentration of 7.7 ppm. The background concentration of arsenic in Emeryville is 14 ppm (8). The concentration of lead in the Garden Area of the Coop ranged from a minimum concentration of 44 ppm to a maximum concentration of 140 ppm, with a geometric mean concentration of 75.5 ppm. The background concentration of lead in Emeryville is 14.7 ppm (8). The concentration of zinc in the Garden Area of the Coop ranged from a minimum concentration of 160 ppm to a maximum concentration of 320 ppm, with a geometric mean concentration of 210 ppm. The background concentration of zinc in Emeryville is 91.5 ppm (8). The concentration of cadmium in the Garden Area of the Coop ranged from less than the limit of detection to 1.3 ppm, with a geometric mean concentration of 0.7 ppm. The geometric mean concentrations of both arsenic and lead exceed their respective Child Screening Values, and the geometric mean concentration of arsenic exceeds the Adult Cancer Risk Evaluation Guide. Therefore, both are contaminants of concern. See Table 5.
The concentration of arsenic in the Patio Area of the Coop ranged from a minimum concentration of less than the limit of detection to a maximum concentration of 5.5 ppm, with a geometric mean concentration of 2.8 ppm. The background concentration of arsenic in Emeryville is 14 ppm. The concentration of lead in the Patio Area of the Coop ranged from a minimum concentration of 14 ppm to a maximum concentration of 730 ppm, with a geometric mean concentration of 28.4 ppm. The background concentration of lead in Emeryville is 14.7. The concentration of zinc in the Patio Area of the Coop ranged from a minimum concentration of 40 ppm to a maximum concentration of 40 ppm, with a geometric mean concentration of 80.9 ppm. The background concentration of zinc in Emeryville is 91.5 ppm. The concentration of cadmium in the Patio Area of the Coop ranged from a minimum of less than the limit of detection to a maximum of 1.3 ppm, with a geometric mean concentration of 0.4 ppm. The background concentration of cadmium in Emeryville is 1.5 ppm. The geometric mean concentration of arsenic and the maximum concentration of lead both exceed the Child Screening Value, and the geometric mean concentration of arsenic also exceeds the adult Cancer Risk Evaluation Guide. Therefore, both are considered contaminants of concern. See Table 6.
The concentration of arsenic in the flower beds adjacent to the 45th Street Building of the Coop ranged from a minimum concentration of less than the limit of detection to a maximum concentration of 920 ppm, with a geometric mean concentration of 74.8 ppm. The background concentration of arsenic in Emeryville is 14 ppm. The concentration of lead in the flower beds adjacent to the 45th Street Building of the Coop ranged from a minimum of less than the limit of detection to a maximum concentration of 3600 ppm, with a geometric mean concentration of 304 ppm. The concentration of zinc in the flower beds adjacent to the 45th Street Building of the Coop ranged from a minimum concentration of less than the limit of detection to a maximum concentration of 2200 ppm, with a geometric mean concentration of 420 ppm. The background concentration of zinc in Emeryville is 91.5 ppm. The concentration of cadmium in the flower beds adjacent to the 45th Street Building of the Coop ranged from a minimum of less than the limit of detection to a maximum concentration of 9.3 ppm, with a geometric mean concentration of 2.0 ppm. The background concentration of cadmium in Emeryville is 1.5 ppm. The geometric mean concentration of both arsenic and lead exceed the Child Screening Value, and the geometric mean concentration of arsenic also exceeds the Adult Cancer Risk Evaluation Guide. Therefore, both are considered contaminants of concern. See Table 7.
The concentration of arsenic in the flower beds adjacent to the Coop Annex ranged from a minimum of less than the limit of detection to a maximum of 50 ppm, with a geometric mean concentration of 9.2 ppm. The background concentration of arsenic in Emeryville is 14 ppm. The concentration of lead in the flower beds adjacent to the Coop Annex ranged from a minimum of 8.7 ppm to a maximum of 610 ppm, with a geometric mean concentration of 107 ppm. The background concentration of lead in Emeryville is 14.7 ppm. The concentration of zinc in the flower beds adjacent to the Coop Annex ranged from a minimum of 37 ppm to a maximum concentration of 870 ppm, with a geometric mean concentration of 271 ppm. The background concentration of zinc in Emeryville is 91.5. The concentration of cadmium in the flower beds adjacent to the Coop Annex ranged from a minimum of less than the limit of detection to a maximum concentration of 7.5 ppm, with a geometric mean concentration of 1.5 ppm. The background concentration of cadmium in Emeryville is 1.5 ppm. The geometric mean concentration of arsenic and lead exceed the Child Screening Value, and the geometric mean concentration of arsenic also exceeds the Adult Cancer Risk Evaluation Guide. Therefore, both are considered contaminants of concern. See Table 8.
At this time, the source(s) of contamination in the soil of the Coop property and along Horton Street is not clearly understood. In general, the concentration of contaminants decreases with increasing depth below ground surface, which suggests surface deposition of the contamination. However, it is not known if the contamination was deposited by fugitive dust emissions, by storm water runoff carrying contaminated soils, or if there were other deposition mechanisms. It is not known what effect, if any, that previous activities at the 45th Street Building when it was owned and/or operated by others in the pass might have on contamination in and around the Coop. The general flow of the shallow ground water in the area is to the north west, so shallow contaminated ground water contamination from the Sherwin-Williams site is not expected to be found beneath the Coop.
Quality Assurance/Quality Control Procedures
According to representatives of LFR, all appropriate quality assurance/quality control (qa/qc) measures were implemented during sample collection and transport to the analytical laboratory. The analytical laboratory used to analyze these samples is certified by the California Environmental Protection Agency, and has its own internal QA/QC procedures. The laboratory QA/QC is reviewed by the laboratory prior to release of the actual data, and are also reviewed by LFR prior to using the data.
Physical and Other Hazards
The Sherwin-Williams site is an active industrial site, with hazards typically found at such sites. Railroad tracks cross the site, and there is also vehicular traffic. There are, however, no extraordinary physical hazards at the site.
There are no physical or other apparent hazards at the Coop. It is located on a relatively busy street in a light industrial/commercial area, and thus there is more truck traffic than is normally found in a residential area. This would probably be a hazard only for younger children.
For a receptor population to be exposed to environmental contamination, there must be a mechanism by which that contamination comes into direct contact with the target population. An exposure pathway is the description of this mechanism. An exposure pathway consists of five parts: a source of contamination, an environmental medium and transport mechanism, a point of exposure, a route of exposure, and a receptor population.
Exposure pathways are classified as completed, potential, or eliminated. A completed exposure pathway is one in which all five elements of the pathway are present. A potential pathway is a pathway in which one or more elements of the pathway are missing, but might be present later. A pathway may also be described as a potential pathway if information on one of the elements of the pathway is missing. An eliminated pathway is one in which one or more of the elements is missing and will not be complete in the future. For a population to be exposed to an environmental contaminant, a completed exposure pathway (all five elements) must be present. If any one or more of these elements are missing, then there is no exposure, though the presence of contamination may still be significant and require remediation. This is especially true if there is a possibility of an incomplete exposure pathway becoming complete in the future.
Completed Exposure Pathways
CDHS identified two completed exposure pathways. One was that of child and adult residents of the Coop being exposed to contamination in the soil on the Coop property and in the flower beds adjacent to the Coop buildings. Children are considered to have been exposed to contamination while playing in the soils of the Patio Area and the Garden Area. Adult Coop residents are considered to have been exposed to contamination in the Patio and Garden areas of the Coop while gardening or engaging in other outdoor recreational activities. The exposure routes for both adults and children could occur through incidental ingestion of soil, inhalation of dust, and dermal absorption of contaminants from soil particles through the skin.
The second completed exposure pathway was that of workers at the Sherwin-Williams facility being exposed to contamination in the soil on the facility property. This exposure would occur while engaging in normal daily work activities at the site. The routes of exposure for Sherwin-Williams workers include incidental ingestion of contaminated soil, inhalation of contaminated dust, and dermal absorption of contamination from soil particles that stick to the skin.
Potentially Completed Exposure Pathways
CDHS identified one potentially completed exposure pathway, that of Coop residents being exposed to contaminants in household dust in their studios. This exposure could occur through incidental ingestion of dust, inhalation of contaminated dust, and dermal absorption of contamination from dust particles that stick to the skin. CDHS is currently investigating this issue, the results of which will be made known in a future document. Until this exposure pathway is fully investigated, it will be classified as a Potentially Completed Exposure Pathway, and will not be considered further in this document.
Eliminated Exposure Pathways
CDHS identified three eliminated exposure pathways. These were the ingestion of contaminated ground water, dermal absorption of contaminants, and inhalation of contaminated dust. Ingestion of ground water was eliminated as a possible exposure pathway because Coop residents use municipal water and do not use local well water. In addition, the ground water is not suitable for drinking water purposes.
Dermal absorption was eliminated because, for metals to be absorbed by the body, soil particles must stick to the skin, the contaminant must move from the soil particle to the skin, and finally pass through the skin and into the body. This is usually a slow and inefficient process. Therefore, dermal absorption of metals is generally only a very small fraction of the total dose, especially when compared to typical ingested doses.
Inhalation of outdoor dust was eliminated as a pathway because it is not known what percentage of soil particles are of a size that can be inhaled into the lungs. For those particles that do reach the lungs, the body's efficiency in absorbing contaminants on these particles is generally not known. Most inhaled particles are trapped by the body before they can reach the lungs, coughed up, and ingested. Using a conservative value for soil ingestion helps account for this inhalation exposure.
Toxicological Evaluation of Completed Exposure Pathways
CDHS has identified and evaluated two completed exposure pathways, that of child and adult Coop residents being exposed to chemical contamination in the soil of the Coop property and the flower beds adjacent to the Coop property, and that of Sherwin-Williams workers being exposed to chemical contamination in the soil.
In the discussions below, conclusions are based on the concentration of the contaminant of concern at soil depths down to 0.5 feet, and upon certain assumptions regarding the receptor population (see Table 1). These assumptions of body weight (70 kg adult [154 pounds], 10 kg child [22 pounds]) and soil ingestion rate (100 mg/day for adults, 200 mg/day for children) are relatively conservative assumptions, meaning that they tend to overestimate the total dose of a contaminant for the receptor population. By using conservative assumptions, one may be more certain that if the dose of a chemical is less than its comparison value, then adverse health effects will not be expected to occur. However, if the dose of a chemical exceeds its comparison value, adverse health effects do not automatically occur. That chemical must be evaluated on an individual basis to determine if adverse health effects would be expected.
In assessing the toxicological effects of contaminants of concern, both the average and maximum concentrations of the contaminant were considered. Ordinarily, people will not be exposed to contaminants in just one location or at just the maximum concentration in an area. Rather, they will more than likely be exposed to the range of concentrations of the contaminant in that area. Therefore, CDHS used the average concentration of the contaminant in an area as an estimate of the overall concentration of the contaminant to which a person is exposed. The average concentration is considered to be an estimate of the concentration because the contamination is not evenly distributed in an area. The maximum concentration of the contaminant was also evaluated as a worst case scenario.
Limitations of Toxicological Evaluations
One problem often encountered during the evaluation process is that of incomplete data. Relatively few chemicals of the many thousands of commonly used chemicals have been thoroughly evaluated for toxicity. For most chemicals, there are data gaps. For example, there may be information on the non-carcinogenic adverse health effects of a particular chemical, but no information as to its potential to cause cancer. Or, there may be information regarding the toxicity of a chemical for short exposures at high concentrations, but little information regarding its toxicity at low concentrations for long periods of time. In these situations, the health implications of exposure cannot be completely evaluated.
Toxicological Effects of Contaminants of Concern in Completed Exposure Pathway
In this section, background information and the toxicological effects of the contaminants of concern are discussed. Zinc and cadmium are not included here because they were not identified as contaminants of concern in any of the sampling areas.
Arsenic (3,8)
Lead (4,5,8)
In the sections below concerning adverse health effects on children and adults, the daily dose of arsenic, calculated from the soil concentration, is compared to the chronic oral MRL for arsenic. Concerning lead, discussion of adverse health effects is based upon estimated blood lead levels, which are estimated using the California Department of Toxic Substances Control Lead Risk Assessment Spreadsheet (6). This model estimates blood lead levels in adults and children given concentrations of lead in the soil, air, drinking water, edible plants, and respirable dust, and a set of physiological parameters such as body weight, food and water ingestion rate, inhalation rate, and the efficiency with which the body absorbs lead from each of these routes of exposure.
This model calculates two sets of numbers, the predicted blood lead level for various receptor populations (adults, children, pica children, and industrial workers), and a Preliminary Remediation Goal (PRG), which is a screening concentration for lead in soil. The output for both sets of numbers are further divided into percentiles. These percentiles represent a percentage of the corresponding receptor population. For both the predicted blood lead level and the PRG, CDHS used the 95th percentile. For blood lead levels, this means that 95 percent of the population would have that blood lead level for a given level of lead exposure. For the PRG, this means that the PRG is protective of 95 percent of the corresponding receptor population.
Toxicological Evaluation of Children Exposed to Arsenic and Lead Through Incidental Ingestion of Contaminated Soil
ATSDR recognizes that infants and children may be more sensitive to exposures than adults in communities with contamination in their water, soil, air, or food. This sensitivity is a result of a number of factors. Children are more likely to be exposed to soil or surface water because they play outdoors and often bring food into contaminated areas. For example, children may come into contact with and ingest soil particles at higher rates than adults do; also, some children with a behavior trait known as "pica" are more likely to ingest soil and other non-food items. Children are shorter than adults, which means they can breathe dust, soil, and any vapors close to the ground. Also, they are smaller, resulting in higher doses of chemical per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Because children depend completely on adults for risk identification and management decisions, ATSDR is committed to evaluating their special interest at applicable sites as a part of the ATSDR Child Health Initiative.
This section evaluates potential adverse health effects on children who are exposed to arsenic and lead through incidental ingestion of contaminated soils. Because the areas with the highest levels of contamination (flower beds, Garden Area) have been cleaned up, these potential adverse health effects are based upon past exposures to contaminated soils. Children will be evaluated for potential adverse health effects only for the Garden and the Patio Areas because it is considered unlikely that very young children would play in the flower beds along a busy street.
Past and Current Exposures for Children Exposed to Contaminants in the Soils of the Garden Area
Arsenic
At an average arsenic concentration of 7.7 ppm, the daily dose of arsenic to a child playing in the Garden Area who might have been exposed to arsenic through incidental ingestion of this contaminated soil on a daily basis before cleanup would have been 1.5 x 10-4 mg/kg/day. Exposure to the maximum concentration of arsenic of 21 ppm through incidental ingestion of soil in the Garden Area on a daily basis would have resulted in a daily dose to that child of 4.2 x 10-4 mg/kg/day. The chronic oral MRL for arsenic is 3 x 10-4 mg/kg/day. Thus, children exposed to the average concentration of arsenic would not have been expected to have experienced adverse health effects, because the daily dose of arsenic is less than the chronic oral MRL for arsenic. The daily dose of arsenic based on the maximum arsenic concentration was greater than the chronic oral MRL, but was approximately two times less than the dose of arsenic shown to cause adverse health effects in humans. Therefore, a child exposed to the maximum concentration of arsenic on a daily basis through the incidental ingestion of contaminated soil in the Garden Area might have experienced dermal adverse health effects.
Lead
At an average lead concentration of 75.2 ppm, the predicted blood lead level for a child exposed to lead through incidental ingestion of soil in the Garden Area prior to its being cleaned up would have been 10.4 µg/dL. This value is just above the 10 µg/dL value considered by the CDC to be an elevated blood lead level for children. At a maximum lead concentration of 140 ppm, the predicted blood lead level for a child exposed to lead through incidental ingestion of soil from the Garden Area prior to its being cleaned up would have been 12.6 µg/dL. Thus, children exposed to lead through the incidental ingestion of soil in the Garden Area on a daily basis before it was cleaned up might have experienced adverse health effects.
Past and Current Exposures for Children Exposed to Contaminants in the Soils of the Patio Area
The results from samples collected from the shallow soils in the Patio Area indicated that the Patio Area did not require cleanup. However, approximately two feet of the top soil in the planters of the Patio Area was fresh soil. Therefore, to reflect potential exposures that would have occurred before the fresh soil was added, the soils at a depth of two or 2.5 feet were evaluated for potential adverse health effects.
Arsenic
At an average arsenic concentration of 2.8 ppm, the daily dose of arsenic to a child playing in the Patio Area who might have been or who might be exposed arsenic through incidental ingestion of this contaminated soil on a daily basis would have been 5.6 x 10-5 mg/kg/day. Exposure to the maximum concentration of arsenic of 5.6 ppm through the incidental ingestion of contaminated soil in the Patio Area on a daily basis would have resulted in a daily dose of arsenic of 1.1 x 10-4 mg/kg/day. Both of these daily doses are less than the chronic oral MRL. Children exposed to arsenic through incidental ingestion of the soils of the Patio Area on a daily basis would not be expected to have experienced dermal adverse health effects.
Lead
At an average concentration of 28.4 ppm, the predicted blood lead level for a child exposed to lead through incidental ingestion of contaminated soil in the Patio Area would have been 8.8 µg/dL. This value is below the 10 µg/dL value considered by CDC to be elevated in children. At a maximum lead concentration of 730 ppm, the predicted blood lead level for a child exposed to lead through the incidental ingestion of contaminated soil in the Patio Area would have been 33.1 µg/dL. This value is greater than the value of 10 µg/dL considered by CDC to be elevated in children. Children exposed on a daily basis to the average concentration of lead in the Patio Area for a period of greater than one year would not be expected to experience adverse health effects. However, children exposed to the maximum concentration of lead on a daily basis for a period of greater than one year would be expected to experience adverse health effects.
Toxicological Evaluation of Adults Exposed to Arsenic and Lead Through Incidental Ingestion of Contaminated Soil
This section evaluates the potential adverse health effects on adults resulting from exposure to contaminants in soils on Coop property and in the flower beds through incidental ingestion of those contaminated soils. Except for the Patio Area, which did not require cleanup, the other three areas have been cleaned up. Therefore, these potential adverse health effects are based on past exposures.
Past and Current Exposures for Adults Exposed to Contamination in the Soils of the Flower Beds Adjacent to 45th Street Building
Arsenic
At an average arsenic concentration of 74.8 ppm, the daily dose of arsenic to an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis in the flower beds adjacent to the 45th Street Building would have been 1.1 x 10-4 mg/kg/day, which is below the chronic oral MRL of 3.0 x 10-4 mg/kg/day. At a maximum arsenic concentration of 920 ppm, the daily dose of arsenic to an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis in the flower beds adjacent to the 45th Street Building would have been 1.3 x 10-3 mg/kg/day, which is a little over four times greater than the chronic oral MRL of 3.0 x 10-4 mg/kg/day, and is also about 1.4 times greater than the dose of arsenic shown to cause dermal adverse health effects in humans. Thus, an adult exposed to the average concentration of arsenic on a daily basis through the incidental ingestion of contaminated soils in the flower beds adjacent to the 45th Street Building would not be expected to have experienced dermal adverse health effects. However, an adult exposed on a daily basis to the highest concentrations of arsenic through the incidental ingestion of contaminated soils in the flower beds adjacent to the 45th Street Building would be expected to have experienced dermal adverse health effects.
The increased lifetime cancer risk to an adult who had been exposed on a daily basis for 24 years (the length of time the Coop has been in operation) to the average arsenic concentration of 74.8 ppm through incidental ingestion of contaminated soil in the flower beds adjacent to the 45th Street Building is 5.6 x 10-5. This is considered to be a very low increased risk. The increased lifetime cancer risk to an adult exposed on a daily basis to the maximum arsenic concentration of 920 ppm through incidental ingestion of contaminated soil in the flower beds adjacent to the 45th Street Building is 6.7 x 10-4. This is considered to be a low increased risk.
Lead
At an average lead concentration of 304 ppm, the predicted blood lead level for an adult exposed to lead on a daily basis through the incidental ingestion of contaminated soil in the flower beds adjacent to the 45th Street Building would have been 5.9 µg/dL. This is below the OSHA standard of 40 µg/dL. Therefore, adults exposed on a daily basis to lead through the incidental ingestion of contaminated soil in the flower beds adjacent to the 45th Street Building would not be expected to have experienced adverse health effects. At a maximum lead concentration of 3600 ppm, the predicted blood lead level for an adult exposed to lead on a daily basis through the incidental ingestion of contaminated soil in the flower beds adjacent to the 45th Street Building is 30.6 µg/dL. This level is below the OSHA standard of 40 µg/dL. An adult exposed only to the maximum concentration of lead on a daily basis through the incidental ingestion of contaminated soil in the flower beds adjacent to the 45th Street Building would not be expected to have experienced adverse health effects.
Past and Current Exposures for Adults Exposed to Contamination in the Soils of the Flower Beds Adjacent to Coop Annex/Horton Street Lofts
Arsenic
At an average arsenic concentration of 9.2 ppm, the dose of arsenic to an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis in the flower beds adjacent to the Coop Annex/Horton Street Lofts would have been 1.3 x 10-5 mg/kg/day. At the maximum arsenic concentration of 50 ppm, the dose of arsenic to an adult exposed to arsenic through the incidental ingestion of contaminated soil on a daily bases in the flower beds adjacent to the Coop Annex/Horton Street Lofts would have been 7.1 x 10-5 mg/kg/day. Both of these doses are below the Chronic Oral MRL for arsenic of 3.0 x 10-4 mg/kg/day. Therefore, adults exposed to arsenic through incidental ingestion of contaminated soil in the flower beds adjacent to the Coop Annex/Horton Street Lofts would not be expected to have experienced dermal adverse health effects.
The increased lifetime cancer risk to an adult who had been exposed on a daily basis for 24 years (the length of time the Coop has been in operation) to the average arsenic concentration of 9.2 ppm through incidental ingestion of contaminated soils in the flower beds adjacent to the Coop Annex/Horton Street Lofts is 6.7 x 10-6. This is considered to be no increased risk. The increased lifetime cancer risk to an adult exposed on a daily basis to the maximum arsenic concentration of 50 ppm through incidental ingestion of contaminated soil from the flower beds adjacent to the Coop Annex/Horton Street Lofts is 3.6 x 10-5. This is considered to be a very low increased risk.
Lead
At an average lead concentration of 107 ppm, the predicted blood lead level for an adult exposed to lead on a daily basis through incidental ingestion of contaminated soil in the flower beds adjacent to the Coop Annex/Horton Street Lofts would have been 4.4 µg/dL. At a maximum lead concentration of 610 ppm, the predicted blood lead level for an adult exposed to lead on a daily basis through incidental ingestion of contaminated soil in the flower beds adjacent to the Coop Annex/Horton Street Lofts would have been 8.2 µg/dL. Both of these values are below the OSHA standard of 40 µg/dL. Therefore, adults exposed to lead on a daily basis through incidental ingestion of contaminated soil in the flower beds adjacent to the Coop Annex/Horton Street Lofts would not be expected to have experienced adverse health effects.
Past and Current Exposures for Adults Exposed to Contamination in the Soils of the Garden Area
Arsenic
At an average arsenic concentration of 7.7 ppm, the daily dose of arsenic to an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis in the Garden Area would have been 1.1 x 10-5 mg/kg/day. At the maximum concentration of arsenic of 21 ppm, the daily dose of arsenic to an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis in the Garden Area in the Garden Area would have been 2.0 x 10-5 mg/kg/day. Both of these doses are below the chronic oral MRL for arsenic of 3.0 x 10-4 mg/kg/day. Therefore, an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis would not be expected to have experienced adverse health effects.
The increased lifetime cancer risk to an adult who had been exposed on a daily basis for 24 years (the length of time the Coop has been in operation) to the average concentration of arsenic of 7.7 ppm through incidental ingestion of contaminated soil on a daily basis in the Garden Area is 5.7 x 10-6. This is considered to be a very low increased risk. The increased lifetime cancer risk to an adult exposed to the maximum concentration of arsenic through incidental ingestion of contaminated soil on a daily basis in the Garden Area is 1.0 x 10-5. This is also considered to be a very low increased risk.
Lead
At an average lead concentration of 75.2 ppm, the predicted blood lead level for an adult exposed to lead through incidental ingestion of soil on a daily basis in the Garden Area would have been 4.2 µg/dL. At the maximum lead concentration of 140 ppm, the predicted blood lead level for an adult exposed to lead through incidental ingestion of soil on a daily basis in the Garden Area would have been 4.7 µg/dL. Both of these values are below the OSHA standard of 40 µg/dL. Therefore, adults exposed to lead through incidental ingestion of soil on a daily basis from the Garden Area would not be expected to have experienced adverse health effects.
Past Exposures for Adults Exposed to Contamination in the Soils of the Patio Area
The results from samples collected from the shallow soils in the Patio Area indicated that the Patio Area did not require cleanup. However, approximately two feet of the top soil in the planters of the Patio Area was fresh soil. Therefore, to reflect potential exposures that would have occurred before the fresh soil was added, the soils at a depth of two or 2.5 feet were evaluated for potential adverse health effects.
Arsenic
At an average arsenic concentration of 2.8 ppm, the daily dose of arsenic to an adult exposed to arsenic through incidental ingestion of soil on a daily basis in the Patio Area is 4.0 x 10-6 mg/kg/day. At the maximum arsenic concentration of 5.6 ppm, the daily dose of arsenic to an adult exposed to arsenic through incidental ingestion of contaminated soil on a daily basis in the Patio Area is 8.0 x 10-6 mg/kg/day. Both of these values are less than the Chronic Oral MRL of 3.0 x 10-4 mg/kg/day. Therefore, adults exposed to arsenic through the incidental ingestion of contaminated soil in the Patio Area would not be expected to experience dermal adverse health effects.
The increased lifetime cancer risk to an adult who had been exposed on a daily basis for 24 years (the length of time the Coop has been in operation) to the average arsenic concentration of2.8 ppm through the incidental ingestion of soil on a daily basis in the Patio Area is 2.1 x 10-6. This is considered to not be an increased risk. The increased lifetime cancer risk to an adult exposed on a daily basis to the maximum concentration of arsenic of 5.6 ppm through incidental ingestion of soil in the Patio Area is 4.1 x 10-6. This is considered to be a very low increased risk.
Lead
At an average lead concentration of 28.4 ppm, the predicted blood lead level for an adult exposed to lead on a daily basis through the incidental ingestion of soil in the Patio Area is 3.9 µg/dL. At a maximum lead concentration of 730 ppm, the predicted blood lead level for an adult exposed to lead on a daily basis through incidental ingestion of soil in the Patio Area is 9.1 µg/dL. Both of these values are below the OSHA standard of 40 µg/dL. Therefore, adults exposed to lead through incidental ingestion of soil in the Patio Area would not be expected to experience adverse health effects.
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