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Health Consultations - Newark, CA

Historical Document

This web site is provided by the Agency for Toxic Substances and Disease Registry (ATSDR) ONLY as an historical reference for the public health community. It is no longer being maintained and the data it contains may no longer be current and/or accurate.


EPA Facility Identification Number: CAD981389653

September 22, 2005

Prepared by:

U.S. Department of Health and Human Services
Agency for Toxic Substances and Disease Registry
Division of Health Assessment and Consultation

Foreword: ATSDR's National Asbestos Exposure Review

Vermiculite was mined and processed in Libby, Montana, from the early 1920s until 1990. We now know that this vermiculite, which was shipped to many locations around the U.S. for processing, contained asbestos.

The National Asbestos Exposure Review (NAER) is a project of the Agency for Toxic Substances and Disease Registry (ATSDR). ATSDR is working with other federal, state, and local environmental and public health agencies to evaluate public health impacts at sites that processed Libby vermiculite.

The evaluations focus on the processing sites and on human health effects that might be associated with possible past or current exposures. They do not consider commercial or consumer use of the products of these facilities.

The sites that processed Libby vermiculite will be evaluated by (1) identifying ways people could have been exposed to asbestos in the past and ways that people could be exposed now and (2) determining whether the exposures represent a public health hazard. ATSDR will use the information gained from the site-specific investigations to recommend further public health actions as needed. Site evaluations are progressing in two phases:

Phase 1: ATSDR has selected 28 sites for the first phase of reviews on the basis of the following criteria:

The U.S. Environmental Protection Agency (EPA) mandated further action at the site based upon contamination in place

- or -

The site was an exfoliation facility that processed more than 100,000 tons of vermiculite ore from Libby mine. Exfoliation, a processing method in which ore is heated and 'popped,' is expected to have released more asbestos than other processing methods.

The following document is one of the site-specific health consultations ATSDR and its state health partners are developing for each of the 28 Phase 1 sites. A future report will summarize findings at the Phase 1 sites and include recommendations for evaluating the more than 200 remaining sites nationwide that received Libby vermiculite.

Phase 2: ATSDR will continue to evaluate former Libby vermiculite processing sites in accordance with the findings and recommendations contained in the summary report. ATSDR will also identify further actions as necessary to protect public health.


From 1966 until 1993, the W. R. Grace & Company plant in Newark, California, located at 6851 Smith Avenue, processed approximately 300,000 tons of vermiculite from the Zonolite mine in Libby, Montana [1]. At one time the plant employed about 18 to 24 persons, including 10 local residents (unpublished information from EPA's database of W.R. Grace documents)a. Over time, it became known that the vermiculite from the Libby mine was contaminated with naturally occurring asbestos fibers. Vermiculite from Libby was found to contain several types of asbestos fibers including the amphibole asbestos varieties tremolite and actinolite and the related fibrous asbestiform minerals winchite, richterite, and ferro-edenite [1]. In this report we will use the term Libby asbestos to refer to the characteristic composition of asbestos contaminating the Libby vermiculite. The Newark plant produced typical vermiculite-based products such as vermiculite concentrate, gypsum, perlite, and peat moss (unpublished information from EPA's database of W.R. Grace documents)b.

The plant is now owned by a building supply company, and vermiculite is no longer processed at the site. The facility is on the southeast edge of San Francisco Bay, approximately 30 miles south of San Francisco. The site is in an area of mixed commercial, industrial, and residential use. Residential housing is on the west side of Smith Avenue. Industrial properties are across Smith Avenue, east of the site. A railroad spur on the west of the site connects to the Union Pacific Railroad, which is approximately 1/8 -mile south of the site [1]. Exfoliation operations at the plant ceased in 1993, and the plant was sold to the present owners in 1997 [1].

Site Demographic Information

1990 US census data indicate that approximately 10,000 people lived within one mile of the site. Demographic information is included in a map of the site (see Appendix A, Figure 1). 1990 US census data also indicate that the majority of homes in the surrounding census tracts were built either before or during the time that the plant was processing vermiculite (see Appendix A, Figure 2).

Site Environmental Data

On February 21, 2001, EPA representatives conducted a facility tour, interviewed current employees, and collected samples of soil, dust, and air at the site [1]. They observed vermiculite in the soil along the rail spur, particularly near the place where the conveyor system was located and along the west wall of the production building. They also noted a sprayed-on fireproofing material which was suspected to contain asbestos in the attic above the sales office and in the ceilings of the building used as a sales office.

EPA representatives selected 13 soil sample locations on the site, and 10 composite and 4 grab samples were collected from these locations. Soil samples were processed in accordance with soil sample procedure ISSI-Libby-01 [1]. Samples were analyzed by polarized light microscopy (PLM) according to method 9002 of the National Institute for Occupational Safety and Health (NIOSH). Sample results reported as tremolite-actinolite indicate the presence of Libby asbestos. Results of the analysis of the samples are shown in Table 1, Appendix B. Eight of the soil samples contained detectible levels of tremolite-actinolite and/or chrysotile asbestos. Samples of vermiculite products found on the site were also sampled and analyzed using NIOSH method 9002. Results of this analysis are shown in Table 2 of Appendix B. Three soil samples and three vermiculite product samples contained between 2% to 4% tremolite-actinolite. Material from the attic of the sales office contained 15% chrysotile.

EPA contractors sampled dust from four horizontal areas inside buildings that had formerly been used for processing or storing vermiculite. Approximately 100 square centimeters per area were sampled by microvacuum dust sampling, a technique that samples settled dust and fibers by drawing air through a 0.45-micrometer pore-size, mixed cellulose esterase filter at a flow rate of 2.0 liter per minute. Sampling was performed for 2 minutes at each location. Air was pulled through the cassettes by battery-powered sampling pumps. Locations sampled included dusty areas such as window sills and the tops of equipment cabinets. Samples were analyzed using method 10312 of the International Standards Organization (ISO). This method uses transmission electron microscopy (TEM) to determine the type of asbestos fibers present, as well as the lengths, widths, and aspect ratios of asbestos structures. Results of the analysis of the dust samples are shown in Table 3, Appendix B. Tremolite-actinolite indicates the presence of Libby asbestos. All four of the microvacuum samples were found to contain asbestos structures. The largest amount of asbestos in dust found at the site came from the machine shop. Sixty-nine tremolite-actinolite structures (1,761,143 asbestos structures per square centimeter (s/cm2) and 2 chrysotile structures (51,408 s/cm2) were detected in the machine shop dust sample.c

Indoor air samples were collected by drawing air through a mixed cellulose esterase filter (0.45 micrometer pore size) over a 7- to 8-hour period. Samples were collected at a height of 5 feet above the floor. Air was pulled through the cassettes by electric sampling pumps. Five air samples were collected in the building in which vermiculite had been processed. Samples were analyzed by ISO method 10312. Results of air sampling are shown in Appendix B, Table 4. Sample results reported as tremolite-actinolite indicate the presence of Libby asbestos. Tremolite-actinolite asbestos fibers were detected in air samples from the warehouse and from the office area in the warehouse at concentration of 0.0019 asbestos structures per cubic centimeter (s/cc), and 0.0046 s/cc, respectively. Airborne chrysotile fibers were detected in the sales office building and in the office area of the warehouse at concentrations of 0.0018 s/cc and 0.0104 s/cc, respectively.

EPA representatives had noted materials that appeared to contain vermiculite in the ceilings of the sales office building and inside the west wall of the production building. This material could also be a source of the chrysotile fibers detected in the air samples. The operations manager at the site told EPA that when the property was purchased by the present owner (Steeler, Incorporated, Drywall Construction Supply), the only W.R. Grace equipment that was left on the site were two air compressors, a couple of air conditioning units, a couple of fork lifts, a sweeper machine, and some hand scales. The manager also said that the company fabricates and distributes steel products for the construction industry and does not use vermiculite. Other employees reported that a brick dumpster with asbestos warning signs was on the site and said that when the yard dust got really bad in the summer, many of them complained often about sore throats, coughing, and difficulty breathing.

ATSDR Site Visit

On August 12, 2003, staff members from ATSDR and the California Department of Health Services Environmental Health Investigations Branch (EHIB) visited the Newark site. ATSDR and EHIB staff reported observations similar to those noted by EPA's contractors. There are two permanent structures are on the site, a sales office building at the southeast corner and a large production building on the southwestern edge of the site. Both buildings are steel-framed structures with roofs and siding of corrugated sheet metal. The entrance and the southeastern portion of the site (up to the production building) are paved. Unpaved areas are located along the northern portion of the site and along a railroad spur that runs north-to-south along the western portion of the site. Although the spur is not used now, employees mentioned that it might be used in the future. The railroad spur originates from the Union Pacific railroad tracks approximately 1/8 mile south of the site.

Remnants of a former conveyor system are located on the rail spur near the production building. The current owner representatives stated that the conveyor system was removed after acquisition of the site. Footprints of 4 silos were evident on a concrete pad near the main building. Near the concrete pad was a sign reading "Vermiculite Concentrate." There was no evidence of any other vermiculite processing equipment at the site.

No evidence of vermiculite, exfoliated vermiculite, or vermiculite waste materials in bulk quantities was observed at the site. Vermiculite flakes were observed in the soil along the railroad spur. According to the site owner representative, Union Pacific sprayed an encapsulant over the soil in this area to temporarily control the potential release of asbestos fibers until the ownership of the spur could be determined and the required soil removal completed.

An inspection of the area surrounding the facility confirmed the census data that indicated that residential housing existed in an area northeast of the site during the time vermiculite was processed on the site. The houses appeared to have been built in the 1950s or 1960s.


The vermiculite processed at this site originated from the mine in Libby, Montana, now known to be contaminated with asbestos. Studies conducted in the Libby community indicate health impacts that are associated with exposure to asbestos [2,3]. The findings at Libby provided the impetus for investigating this site, as well as other sites across the nation that received asbestos-contaminated vermiculite from the Libby mine. It is important to recognize, however, that the asbestos exposures documented in the Libby community are in many ways unique and will not collectively be present at other sites that processed or handled Libby vermiculite. The site investigation at the Newark plant is part of a national effort to identify and evaluate potential exposure to asbestos at these other sites.

Exposure Assessment and Toxicologic Evaluation

Evaluating the health effects of exposure to Libby asbestos requires extensive knowledge of both exposure pathways and toxicity data. The toxicologic information about asbestos that is currently available is limited, and the exact level of health concern for exposure to different sizes and types of asbestos remains controversial. In addition, information is limited or unavailable on some specific exposure pathways at this site for the following reasons.

  • Information is limited concerning past concentrations of Libby asbestos in air in and around the plant. In addition, significant uncertainties and conflicts exist concerning the methods used to analyze asbestos. This makes it hard to estimate the levels of Libby asbestos to which people may have been exposed.
  • Most exposure occurred long ago. Little information is available about how people who did not work at the plant came into contact with Libby asbestos and how long they were exposed. This information is necessary to estimate quantitative exposure doses.
  • We do not know how some vermiculite materials, such as waste rock, were handled or disposed of. Not knowing whether this material was made available for people in the community to use makes it difficult to identify and assess both past and present potential exposures.

Given these difficulties, the public health implications of past operations at this site are evaluated qualitatively. Current health implications are likewise evaluated qualitatively. The following sections describe the various types of evidence we used to evaluate exposure pathways and reach conclusions about the site. Definitions for the hazard category terminology used to characterize the pathways is presented in Appendix C. Appendix D provides a review of tremolite asbestos toxicity and standards.

Exposure Pathway Analysis

An exposure pathway describes how a person comes into contact with chemicals originating from a source of contamination. Every exposure pathway consists of the following five elements: (1) a source of contamination; (2) an environmental medium (such as air or soil) through which the contaminant is transported; (3) a point of exposure, the place where a person can come into contact with the contaminant; (4) a route of exposure, the way the contaminant enters or comes into contact with the body; and (5) a receptor population. A pathway is considered complete if all five elements are present and connected. Potential exposure pathways indicate that exposure to a contaminant could have occurred in the past, could be occurring currently, or could occur in the future. A potential exposure exists when information about one or more of the five elements of an exposure pathway is missing or uncertain. An incomplete pathway is missing one or more of the pathway elements; it is likely that the elements were never present, and that they are not likely to be present at a later point in time. An eliminated pathway was a potential or completed pathway in the past, but to prevent present and future exposures has had one or more of the pathway elements removed.

After reviewing information from Libby, Montana, and from facilities that processed vermiculite from Libby, the National Asbestos Exposure Review team identified likely exposure pathways for vermiculite processing facilities. All pathways have a common source—vermiculite from Libby contaminated with Libby asbestos—and a common route of exposure—inhalation. Although asbestos ingestion and dermal exposure pathways could exist, health risks from these pathways are minor in comparison to those resulting from inhalation exposure to asbestos, and therefore will not be evaluated.

The exposure pathways considered for each site are listed in the following table. Not every pathway identified will be a significant source of exposure for a particular site. An evaluation of the pathways for this site is presented in the following text.

Table 1. Summary of Pathways Considered for the Newark Plant

[image: HC_NewarkCA_table1.jpg]

Occupational (former W.R. Grace employees) — The occupational exposure pathway for people who worked at the Newark plant prior to 1994 is considered complete. Former W.R. Grace workers were exposed to airborne levels of asbestos that posed a public health hazard. W.R. Grace records indicate that workers were exposed to high indoor levels of Libby asbestos in the air. Employee air sample results for the years 1975 to 1987 (unpublished information from EPA’s database of W.R. Grace documents) are shown in Appendix A, Figure 3. For the personal air monitor samples for which sampling times were provided, the duration of the sampling period ranged from 12 to 120 minutes. Three 8-hour time-weighted-averages were reported in a 1987 industrial hygiene audit of the plant. However, these results were below the analytic limit of detection.

Because total sampled duration for most of the samples was below the total work shift, these samples do not directly represent 8-hour time-weighted-averages. However, based on field observations of two active vermiculite exfoliation facilities, employee job tasks are similar throughout the workday. Therefore, for purposes of evaluating potential exposure concentrations from these data, ATSDR took an overall average for employee exposure data per sampling event.

Individual sample results ranged from non-detect to 11.50 fibers per cubic centimeter (f/cc). Average fiber sample results from personal sampling ranged from a high of 4.34 f/cc in 1977 to 0.03 f/cc in 1987. According to information obtained from W.R. Grace records, efforts were underway to control fiber levels inside the plant through local exhaust ventilation systems in 1976. Accordingly, fiber levels appear to have decreased after 1976. According to these sampling data, by 1987 indoor fiber levels inside the plant were probably compliant with the present OSHA permissible exposure limit of 0.1 f/cc. Area samples collected by W.R. Grace show that concentrations of fibers up to 23 f/cc were generated by plant operations. These levels declined through 1987, as shown in Appendix A, Figure 4.

While no specific health data are available for this particular plant, two studies indicate that Libby vermiculite exfoliation workers are at risk for developing lung disease related to asbestos exposure. The first is a report of a person developing fatal asbestosis as a result of working two summers in a vermiculite exfoliation facility [4]. The second report is a study that was conducted in response to a report of 12 cases of pleural effusion within a 12-year period in an Ohio fertilizer plant that expanded and used Libby vermiculite [5]. The study of this cohort demonstrated cumulative tremolite-actinolite fiber exposure was correlated with dyspenea and pleuritic chest pain, and on chest radiographs pleural changes (thickening and/or plaques with and without calcification) [5]. Inhalation of airborne asbestos above the OSHA PEL would increase the risk for asbestos-related disease and therefore would have posed a public health hazard to former employees. Employee interviews conducted at other W.R. Grace sites by EPA and internal W.R. Grace documents indicate that a respiratory protection program was in place at least by 1986. Depending on the date the program started, the areas where respiratory protection was required, and the effectiveness of this program, the hazard to the employees could have been reduced significantly.

Occupational (past, current, and future employees) — From 1997 until 2002, workers at the plant were exposed to residual asbestos which may have come from vermiculite. Internal documents indicate that W.R. Grace conducted air sampling in 1994 (after plant operations had ceased) to determine whether airborne fibers remained in the building. Although the W.R. Grace 1994 samples did not find airborne asbestos inside the building, residual sources of asbestos remained in the building, as shown by the EPA air and surface sampling. EIHB wrote a health consultation concerning the air levels of asbestos reported by EPA in the remedial assessment and determined that the highest level of asbestos detected might pose an increased cancer incidence risk, but did not pose an “immediate” threat to public health. Because only a limited amount of air sampling results was available, EIHB concluded that the asbestos exposure at the site was an indeterminate public health hazard. EIHB recommended further air monitoring or evaluation and elimination of the sources of the asbestos exposure [6]. EPA ordered a removal action that included remediation of the horizontal surfaces inside the warehouse area and any exposed contaminated soil on the site; this was completed in 2002 [7]. However, confirmatory performed [8]. We therefore believe there is a potential for present and future exposures until such confirmatory sampling is completed.

Household contacts — The pathway for exposure of household members to airborne Libby asbestos brought home inadvertently by former workers (persons who worked at the plant before 1993) is considered complete. If workers did not shower and change clothes before leaving work, members of the workers’ families or other household contacts could have been exposed to asbestos fibers brought home on workers’ bodies or clothing. Family or other household contacts could have come into contact with Libby asbestos by direct contact with the worker, by laundering the worker’s clothing, or by the resuspension of dust during cleaning activities. Exposures to household contacts cannot be estimated without information concerning Libby asbestos levels on worker clothing and behavior-specific factors (for example, worker practices, household laundering practices). ATSDR does not know whether procedures to reduce the amount of fibers that workers took home were implemented at this plant. However, exposure to asbestos resulting in asbestos-related disease in family members of persons who worked in the asbestos industry has been well-documented [9]. Inhalation of Libby asbestos fibers by household contacts because of worker take-home contamination is therefore considered a past public health hazard.

The exposure pathway is considered complete for household contacts of persons who worked at the site after vermiculite production stopped but before EPA’s removal action in 2002. However, the overall low levels of airborne asbestos detected by EPA indicate that exposure from contaminants brought home by workers would be minimal. Therefore, ATSDR considers this exposure of household contacts of these workers to present no apparent public health hazard.

Waste piles — Persons who disturbed vermiculite waste piles could have been exposed to airborne asbestos. Stoner rock (the waste rock created in the exfoliation process) contains up to 10% asbestos by weight (personal communication with James Kelly and Jean Small-Johnson of the Minnesota Department of Health). At other exfoliation sites, waste rock was a significant exposure pathway to the community. For instance, at the Western Minerals plant in Minneapolis, children played in the waste piles and waste rock was given to the surrounding community for fill material and other uses [10].

An internal W.R. Grace document indicates that the Durham Road Landfill, Freemont, California, may have received waste from the Newark plant that contained asbestos. Waste manifests for the asbestos waste from the plant were supplied to ATSDR for the years 1985 and 1990. Steeler employees told EPA that when they took possession of the property, a dumpster with an asbestos warning label on it was on the site [1].

Because information about waste handling procedures at the plant is available for only a period of the plant’s operations, exposure to waste piles at the site before 1985 was determined to be an indeterminate public health hazard. After 1985, community exposure to on-site waste piles appears to have been eliminated.

The facility no longer processes vermiculite, and EPA and ATSDR representatives did not find evidence of waste piles on the site during their site visits. Current and future exposure to waste rock at the site has been eliminated.

On-Site Soil — The exposure pathway concerning current workers or contractors disturbing contaminated soil on the site—including residual contamination or buried waste—is considered an eliminated pathway for both the present and future. EPA sampling showed residual vermiculite contaminated with Libby asbestos in the soil around the plant. Soil with the highest levels of contamination was covered with grass or railroad ballast [1]. EPA required encapsulation and eventual removal of the soil containing Libby asbestos from the spur and the back lot of the plant. Some areas of the site have trace amounts of asbestos. Disturbing soil containing trace amounts of Libby asbestos can result in airborne levels of Libby asbestos fibers [11]. However, the trace amounts of asbestos were located in areas that were not accessible (for example, under asphalt), and EPA was negotiating institutional controls to prevent disturbance of the soil in a manner that would generate airborne asbestos. Because the EPA removal action required either encapsulation or removal of the asbestos-contaminated soil, ATSDR considers the future and current exposure pathways to be eliminated. ATSDR considers past exposure from on-site soil to be no apparent public health hazard assuming no significant disturbances of the soil occurred.

Ambient air — Past exposure to airborne fibers from plant emissions is considered a potential exposure pathway for the community surrounding the site as well as for nearby workers. This exposure was categorized as an indeterminate public health hazard because the asbestos fiber concentration that was present is unknown. Specific information concerning historical emissions from the exfoliation processes at the plant is not available; therefore, an estimate of the health effects from this exposure cannot be made. It is likely that emissions occurred from ore handling activities, exfoliation units, and local exhaust ventilation. Figure 5 in Appendix A shows the wind rose from a meteorological station located 21 miles from the site. An analysis of this wind rose indicates that predominant wind direction is toward the east. However, an individual’s exposure will be driven by factors other than wind direction, factors such as the plant’s operational cycles and the times and locations where people would have been exposed. Community members and area workers could have been exposed to Libby asbestos fibers released into the ambient air from fugitive dusts or the furnace stack while the plant was running. Exposure of the public to airborne emissions downwind of the site would have been at much lower concentrations than that experienced by the W.R. Grace workers. Some contamination of nearby businesses may have occurred from the airborne dispersal of asbestos fibers.

Residential outdoor — Some vermiculite processing facilities in the United States allowed or encouraged workers and nearby community members to take stoner rock, vermiculite, or other process materials for personal use [10]. Some vermiculite sites have disposed of waste rock by burying it on site as fill material [12]. Available documentation dating back to 1985 indicated waste from the facility was shipped to various landfills for disposal. Actual quantities of waste generated and disposed of could not be verified from this information. Because the facility processed a high tonnage of Libby vermiculite in the past and insufficient information is available concerning historical waste disposal, the past, present, and future community exposures to waste rock brought home for personal use are considered to present an indeterminate public health hazard.

Residential indoor — Insufficient information is available concerning past air emissions and community use of waste rock. Therefore, residential indoor exposure to Libby asbestos fibers presents an indeterminate past public health hazard.

The facility does not currently process Libby vermiculite, therefore facility emissions are not currently a source for Libby asbestos contamination in nearby homes. Residual Libby asbestos (from potential past sources) is possible, though housekeeping (particularly wet cleaning methods) over the past 10 years would probably have removed most residual fibers. As discussed in the residential outdoor pathway section, not enough information is available to know whether waste rock was used at homes in the community. Exposure to Libby asbestos from waste rock in the community would primarily be an outdoor exposure concern; the waste rock alone would not be expected to significantly contribute to residential indoor exposures. Therefore the residential indoor exposure pathway is considered no apparent public health hazard for community members now or in the future.

Consumer Products — People who purchased and used company products that contain Libby asbestos may be exposed to asbestos fibers by using those products in and around their homes. At this time, determining the public health implication of commercial or consumer use of company products (such as home insulation or vermiculite gardening products) that contain Libby vermiculite is beyond the scope of this evaluation. Additional information for consumers of vermiculite products has been developed by EPA, ATSDR, and NIOSH and provided to the public (see ATSDR Web site).

Contaminated vermiculite insulation in homes and in soil could pose an inhalation hazard if it were disturbed. Therefore, exposure to asbestos in vermiculite insulation in an uninhabited attic or behind walls should be negligible provided the materials are not disturbed. Exposure to asbestos in soil is less likely if the soil is covered by asphalt, concrete, or vegetation. Asbestos fibers do not break down in the environment, and asbestos in soil may remain for decades [13].

Health Outcome Data

As a separate project, ATSDR’s Division of Health Studies has funded states to perform health statistics reviews around sites that have received vermiculite from Libby. The California Department of Health Services’ Environmental Health Investigation Branch has performed a review of cancer incidence data for the Newark site. The results of the health statistics review are presented and discussed in Appendix E.

Summary of Removal and Remedial Actions

  • Completed and Proposed EPA has overseen a removal action at this site that included
  • Remediation of the horizontal surfaces inside buildings (April 8–12, 2002)
  • Remediation of highly contaminated soil (>1% asbestos content) on the site and along the railroad spur (October 21–November 11, 2002)
  • Institutional controls to prevent disturbance of soil contaminated with asbestos (proposed and being negotiated by EPA).

Child Health Considerations

ATSDR recognizes that infants and children may be more vulnerable than adults to exposures in communities faced with environmental contamination. Because children depend completely on adults for risk identification and management decisions, ATSDR is committed to evaluating their special interests at the site as part of the ATSDR Child Health Initiative.

The effects of asbestos on children are thought to be similar to the effects on adults. However, children could be especially vulnerable to asbestos exposures because they are more likely to disturb fiber-laden soil or indoor dust while playing. Children also breathe air that is closer to the ground and may thus be more likely to inhale airborne fibers from contaminated soil or dust.

Furthermore, children who are exposed could be more at risk of actually developing asbestos-related disease than people exposed later in life because of the long latency period between exposure and onset of asbestos-related respiratory disease.

Because of the limited amount of information regarding the exposure pathways at this site, the health implications for children are difficult to determine. During the time the facility exfoliated Libby vermiculite, the most at-risk children were those who were household contacts of former workers while the plant was expanding vermiculite. Other exposure pathways (ambient air, residential outdoor, waste piles) may also have affected children, but ATSDR does not have information at this time to determine whether these pathways were completed or not. We do not know if the facility gave vermiculite waste materials to the community for use. If this practice occurred, it could represent an ongoing exposure to children in the community.


Occupational Exposure Pathways

  • People who worked at the Newark plant from 1966 to 1993 were exposed to airborne levels of Libby asbestos above current occupational standards. Repeated exposure to airborne Libby asbestos at these elevated levels increased a worker’s risk for asbestos-related disease and therefore posed a public health hazard to former employees.
  • Workplace exposures at the site from 1997 until the presentd are an indeterminate public health hazard due to incomplete data.

Household Contacts

Persons who lived in a household with someone who worked at the plant before 1994 may have been exposed to asbestos fibers brought into the home on workers’ bodies or clothing. This past exposure represents a public health hazard to household contacts of former workers. No apparent public health hazard exists for household contacts of person who worked at this site between 1997 and the completion of the remedial action in 2002.

Waste Piles

  • Community exposure to waste piles at the site in the past posed an indeterminate public health hazard. Available information regarding the waste practices at this site is inadequate to determine whether the public had access to the waste piles.
  • Currently, the facility does not process vermiculite from Libby, and no waste piles were observed at the site. Therefore, no exposure pathway exists for community members to be exposed to contaminated waste piles at the site now or in the future and therefore no public health hazard exists for present and future exposure.

On-Site Soil

  • Under current conditions, and even assuming occasional contact with areas that may contain Libby asbestos, on-site exposure of workers and contractors to Libby asbestos-contaminated soils poses no apparent public health hazard. If asbestos-contaminated soil is disturbed as a result of changes in site conditions or use of the property, a public health hazard could be created.

Ambient Air

  • Insufficient data exist to evaluate past asbestos exposure to the community from air emissions of asbestos from the plant. Therefore, past exposure to ambient air presents an indeterminate public health hazard.
  • Present and future community exposure to Libby asbestos in air has been eliminated because the facility no longer processes vermiculite from Libby.

Residential Outdoor

  • Because the facility processed a high tonnage of Libby vermiculite in the past and insufficient information is available concerning historical waste disposal practices, exposure to persons in the community from waste rock brought home for personal use has been categorized as an indeterminate public health hazard for past, present, and future exposures.

Residential Indoor

  • Insufficient information is available to evaluate past indoor residential exposures, therefore this pathway poses an indeterminate public health hazard to the community.
  • Because this site stopped processing vermiculite in 1993, current indoor residential exposures pose no apparent public health hazard to the community.


Occupational and Household Contacts Exposure

  • Promote awareness of past asbestos exposure among former workers and members of their households.
  • Encourage former workers and their household contacts to inform their regular physician about their exposure to asbestos. If former workers or their household contacts are concerned or symptomatic, they should be encouraged to see a physician who specializes in asbestos-related lung diseases.
  • Conduct air and dust confirmation sampling inside the former processing building to verify the effectiveness of the EPA removal action.

Waste Piles and Residential Outdoor Exposure

  • Promote awareness of potential past asbestos exposure among community members who lived near the facility from1966 to 1993. Provide these people with easily accessible materials that will assist them in identifying their own potential for exposure.
  • Encourage persons who lived in the community in the past and feel they were exposed to inform their regular physician about their potential asbestos exposure.

On-Site Soil Exposure

  • Develop plans to ensure that adequate controls are in place to protect workers from asbestos exposure during excavation or disturbance of on-site soil, including soil beneath the asphalt parking areas.

Public Health Action Plan

The purpose of the public health action plan is to ensure that public health hazards are not only identified, but also addressed. The public health action plan for this site describes actions that ATSDR and/or other government agencies plan to take at the site to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. ATSDR will also follow up on the plan to ensure implementation of the public health actions.

Actions Completed

  • EPA conducted a site visit in February 2001.
  • EPA completed a removal action in 2002.
  • ATSDR visited the site in August 2002.

Actions Ongoing

  • ATSDR is developing a site-specific communication and education plan for the former W.R. Grace & Company site in Newark; the primary goal of the plan is to promote knowledge and awareness of the health effects of asbestos among exposed individuals and concerned community members.
  • ATSDR is available to provide consultative services regarding confirmation sampling inside the buildings.

Actions Planned

  • ATSDR, in cooperation with state partners, is researching and determining the feasibility of conducting additional worker and household contact follow-up activities.
  • ATSDR will notify the current site owner that we recommend confirmation sampling inside the building to verify the effectiveness of clean-up activities. ATSDR is available to provide consultative services to the owner regarding confirmation sampling.
  • ATSDR will notify the current site owner, as well as local permitting authorities, that management plans should be developed to protect workers from asbestos exposure during excavation or disturbance of on-site soil, including soil beneath the asphalt parking areas.
  • ATSDR will combine the findings from this health consultation with findings from other sites nationwide that received Libby vermiculite to create a comprehensive report outlining overall conclusions and strategies for addressing public health implications.

Site Team


James T. Durant, MSPH, CIH
Environmental Health Scientist
Exposure Investigations and Consultation Branch (EICB)
Division of Health Assessment and Consultation (DHAC)
Agency for Toxic Substances and Disease Registry (ATSDR)

Technical Assistance/Project Coordination

Barbara Anderson MS, PE
Environmental Health Scientist, Consultation Team

Health Statistics Review

Jackie Schwartz, MPH
Epidemiologist, Environmental Health Investigations Branch
California Department of Health Services

Kevin Horton, MSPH
Division of Health Studies, Epidemiology and Surveillance Branch, ATSDR

Regional Representative

Libby Levy
Environmental Health Specialist
Office of Regional Operations, Region 9

Reviewed by

John Wheeler, PhD, DABT

Susan Moore, M.S.
Branch Chief EICB, DHAC, ATSDR


1. US Environmental Protection Agency. Focused removal assessment report for Steeler Incorporated (former W.R. Grace facility): CDM for US Environmental Protection Agency; 2001.

2. Agency for Toxic Substances and Disease Registry. Health consultation on mortality in Libby, Montana. Atlanta: U.S. Department of Health and Human Services; August 2002.

3. Peipins LA, Lewin M, Campolucci, Lybarger JA, Miller A, Middleton D, et al. Radiographic abnormalities and exposure to asbestos-contaminated vermiculite in the community of Libby, Montana. Environ Health Perspect 11:1753-9. Also doi:10.1289/ehp.6346 (online July 2, 2003) at ATSDR Web site

4. Wright R, Abraham J, Harper P, Burnett B, Morris P, West P. Fatal asbestos 50 years after brief high intensity exposure in a vermiculite expansion plant. Am J Respir Crit Care Med 165:1145-9.

5. Lockey JE, Brooks SM, Jarabek AM, Khoury PR, McKay RT, Carson A, et al. Pulmonary changes after exposure to vermiculite contaminated with fibrous tremolite. Am Rev Respir Dis 129(6):952-8.

6. California Department of Health Services, under a cooperative agreement with ATSDR. Steeler, Incorporated, Drywall Construction Supply. Atlanta: US Department of Health and Human Services; July 2002.

7. US Environmental Protection Agency. Pollution report concerning Steeler, Inc., removal action. San Francisco; November 14, 2002.

8. Coffman MA, Singh J. Asbestos management in buildings. In: Patty’s industrial hygiene th edition. New York: John Wiley & Sons, Inc.; 2000.

9. Powell C, Cohrssen B. Asbestos. In: Bingham E, Cohrssen B, Powell C, editors. Patty's toxicology 5th edition. New York: John Wiley & Sons, Inc.; 2001.

10. Minnesota Department of Health, under cooperative agreement with the Agency for Toxic Substances and Disease Registry. Health consultation for Western Mineral Products site (a/k/a Western Mineral Products), City of Minneapolis, Hennepin County, Minnesota. Atlanta: U.S. Department of Health and Human Services; May 2001.

11. Weis CP (EPA). Memorandum to P. Peronard of EPA. Amphibole mineral fibers in source materials in residential and commercial areas of Libby pose an imminent and substantial endangerment to public health. Denver: EPA; December 20, 2001.

12. Scott R Smith Environmental Management Consultants, Inc. Site investigation former W.R. Grace & Co—Conn Property, Wilder, Campbell County, Kentucky; July 5, 2000.

13. Agency for Toxic Substances and Disease Registry. Toxicological profile for asbestos (update). Atlanta: US Department of Health and Human Services; September 2001.

Appendix A - Figures

Figure 1

Figure 1

Figure 2. Census Data on Age of Houses

Figure 2. Census Data on Age of Houses

igure 3. Asbestos Levels Detected in Air Samples

Figure 3. Asbestos Levels Detected in Air Samples From Personal Air Monitors of Workers at the W. R. Grace Plant in Newark. Collected by W. R. Grace.

Figure 4. Asbestos Levels Detected in Air Samples

Figure 4. Asbestos Levels Detected in Air Samples From Personal Air Monitors of Workers at the W. R. Grace Plant in Newark. Collected by W. R. Grace.

Figure 5. Wind Rose From Oakland International Airport

Figure 5. Wind Rose From Oakland International Airport

Appendix B. EPA Sampling Results (PDF, 45 KB)

Appendix C. Health Hazard Category Definitions (PDF, 19 KB)

Appendix D. Tremolite Asbestos Toxicology (PDF, 55 KB)

Appendix E. Health Statistics Review (PDF, 370 KB)

a Unpublished data from an EPA database of W.R. Grace invoices for shipments of vermiculite from the Libby mine from 1964 to 1990.

b Unpublished data from a database of W.R. Grace documents that EPA Region 8 obtained through legal means during the Libby mine investigation. This document database contains confidential business information as well as private information that is not available to the public.

c See Appendix B for conversions of TEM results to s/cm.2

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