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PUBLIC HEALTH ASSESSMENT

MANY DIVERSIFIED INTERESTS, INCORPORATED
HOUSTON, HARRIS COUNTY, TEXAS


INTRODUCTION

The Agency for Toxic Substances and Disease Registry (ATSDR) was established under themandate of the Comprehensive Environmental Response, Compensation, and Liability Act(CERCLA) of 1980. This act, also known as the "Superfund" law, authorized the U.S.Environmental Protection Agency (EPA) to conduct clean-up activities at hazardous waste sites. EPA was directed to compile a list of sites considered hazardous to public health. This list istermed the National Priorities List (NPL). The 1986 Superfund Amendments andReauthorization Act (SARA) directed ATSDR to prepare a public health assessment (PHA) foreach NPL site. (Note: Appendix A provides a listing of abbreviations and acronyms used in this report.)

In conducting the PHA, three types of information are used: environmental data, communityhealth concerns and health outcome data. The environmental data are reviewed to determinewhether people in the community might be exposed to hazardous materials from the NPLfacility. If people are being exposed to these hazardous materials, ATSDR will then determinewhether the exposure is at levels which might cause harm. Community health concerns arecollected to determine whether health concerns expressed by community members could berelated to exposure to hazardous materials released from the NPL facility. If the communityraises concerns about specific diseases in the community, health outcome data (information fromstate and local databases or health care providers) can be used to address the communityconcerns. Also, if ATSDR finds that harmful exposures have occurred, health outcome data canbe used to determine if illnesses are occurring which could be associated with the hazardouschemicals released from the NPL facility.

In accordance with the Interagency Cooperative Agreement between ATSDR and the TexasDepartment of Health (TDH), ATSDR and TDH have prepared this PHA for the ManyDiversified Interests, Inc., NPL site. This PHA presents conclusions about whether exposuresare occurring, and whether a health threat is present. In some cases, it is possible to determinewhether exposures occurred in the past; however, often a lack of appropriate historical datamakes it difficult to quantify past exposures. If it is found that a threat to public health exists,recommendations are made to stop or reduce the threat to public health.


SUMMARY

The Many Diversified Interests, Inc., National Priorities List site, is a 35-acre inactive facility inHouston, Harris County, Texas. The site operated as a steel casting facility from 1926 until1992. Operations at the site have contaminated soil on the site with heavy metals and othersubstances. There is sufficient evidence to suggest that past operations have contaminated soilfrom nearby residential yards with lead.

The Agency for Toxic Substances and Disease Registry (ATSDR) reviewed availableenvironmental information for the site and evaluated several potential exposure situations. Theseexposure situations include potential contact with site contaminants in surface soil, ambient air,waste material, and surface water. Although site-related contaminants have been found inseveral of these media, at present the contaminants are either at concentrations below publichealth concern or in areas where access is restricted. We identified one past exposure pathway asa public health hazard (residential soil), two past exposure pathways as indeterminate publichealth hazards (air and on-site contaminants), and two past exposure pathways as no apparentpublic health hazard (air during demolition activities and surface water runoff). The presentcondition of the site is different than it was in the past. We identified three present exposurepathways as no public health hazard (residential soil, air, and on-site) and one present exposurepathway as no apparent public health hazard (surface water runoff). Based on availableinformation, we have concluded that, at present, the Many Diversified Interests, Inc., site doesnot pose a public health hazard.

The conclusion category for the overall site could change if access to the site changes, if siteconditions change, or if additional data indicate that either of the indeterminate pathways pose athreat to public health. A brief review of the exposure pathways that were considered is presented in the following section.

Residential Soil Exposure Pathway

We have concluded that prior to removal, lead in the soil from residential yards posed a publichealth hazard because chronic exposure to lead in soil could have an adverse impact on the healthand well being of young children. Since soil identified as having elevated levels of lead has beenremoved and replaced with non-contaminated soil, residential soil no longer poses a public healthhazard.

Air Exposure Pathway

We have concluded that past exposure to site contaminants in the air is an indeterminate publichealth hazard. Although there is sufficient indirect evidence to suggest that in the past, airemissions from the facility may have reached residential areas, we could not quantify with anydegree of certainty the public health significance of these emissions. Exposure to contaminantsin the air during the demolition activities posed no apparent public health hazard because therewas no evidence that people would have come into contact with contaminants at concentrationshigh enough to cause adverse health effects. Since the site is no longer operating, there is nopresent public health hazard from breathing air near the site.

On-Site Contamination Exposure Pathway

Currently, contaminants on the site do not pose a public health hazard because access to the siteis restricted. Although access to the site was not always restricted, the lack of historical exposureinformation has led us to conclude that past exposure to contaminants on the site by trespassers,is an indeterminate public health hazard.

Surface Water Exposure Pathway

Based on our best professional judgement, we have concluded that exposure to surface water run-off from the site poses no apparent public health hazard. Additional data could confirm or refute this conclusion category.


ATSDR PUBLIC HEALTH CONCLUSION CATEGORIES
CATEGORY A.
URGENT PUBLIC HEALTH HAZARD 1

This category is used for sites where short-term exposures (<1 yr) to hazardous substances or conditions could result in adverse health effects that require rapid intervention.

Criteria:
Evaluation of available information2 indicates that site-specific conditions or likely exposures have had, are having, or are likely to have in the future, an adverse impact on human health that requires immediate action or intervention. Such site-specific conditions or exposures may include the presence of serious physical or safety hazards, such as open mine shafts, poorly stored or maintained flammable/explosive substances, or medical devices which, upon rupture, could release radioactive materials.

CATEGORY B.
PUBLIC HEALTH HAZARD
1

This category is used for sites that pose a public health hazard due to the existence of long-term exposures (>1 yr) to hazardous substances or conditions that could result in adverse health effects.

Criteria:
Evaluation of available relevant information2 suggests that, under site-specific conditions of exposure, long-term exposures to site-specific contaminants (including radionuclides) have had, are having, or are likely to have in the future, an adverse impact on human health that requires one or more public health interventions. Such site-specific exposures may include the presence of serious physical hazards, such as open mine shafts, poorly stored or maintained flammable/explosive substances, or medical devices which, upon rupture, could release radioactive materials.

CATEGORY C.
INDETERMINATE PUBLIC HEALTH HAZARD

This category is used for sites in which "critical" data are insufficient with regard to extent of exposure and/or toxicologic properties at estimated exposure levels.

Criteria:
The health assessor must determine, using professional judgement, the "criticality" of such data and the likelihood that the data can be obtained and will be obtained in a timely manner. Where some data are available, even limited data, the health assessor is encouraged to the extent possible to select other hazard categories and to support their decision with clear narrative that explains the limits of the data and the rationale for the decision.

CATEGORY D.
NO APPARENT PUBLIC HEALTH HAZARD
1

This category is used for sites where human exposure to contaminated media may be occurring, may have occurred in the past, and/or may occur in the future, but the exposure is not expected to cause any adverse health effects.

Criteria:
Evaluation of available information2 indicates that, under site-specific conditions of exposure, exposures to site-specific contaminants in the past, present, or future are not likely to result in any adverse impact on human health.

CATEGORY E.
NO PUBLIC HEALTH HAZARD

This category is used for sites that, because of the absence of exposure, do NOT pose a public health hazard.

Criteria:
Sufficient evidence indicates that no human exposures to contaminated media have occurred, none are now occurring, and none are likely to occur in the future.

1 This determination represents a professional judgement based on critical data which ATSDR has judged sufficient to support a decision. This does not necessarily imply that the available data are complete; in some cases additional data may be required to confirm or further support the decision made.

2 Such as environmental and demographic data; health outcome data; exposure data; community health concerns information; toxicologic, medical, and epidemiologic data.


BACKGROUND

Site Description and History

The Many Diversified Interests, Inc. (MDI) site is a 41-acre inactive facility located at 3617 BaerStreet in the Fifth Ward area of the city of Houston, Harris County, Texas (Figure 1). The areaaround MDI consists of both residential and commercial properties with Bruce ElementarySchool located immediately west of the site, industrial facilities are south and east of the site, andInterstate Highway 10 is north.

The MDI site operated as a steel casting facility from 1926 until 1992 under the company namesTexas Electric Steel Casting Company (TESCO) and San Jacinto Foundry (SJF). TESCOmanufactured specialty molds and cast specialty parts such as large wheels, tracks, anddragline/shovel teeth for mining equipment. Process operations at the TESCO facility includedcasting many different types of steel, such as chrome, molybdenum, nickel, and various types ofstainless steel. Scrap steel and iron were melted in a metal scrap yard which operated on aportion of the MDI site.

During the mid-1980s, a part of the site was leased to Can-Am Resources Group to operate aspent catalyst recycling operation. Can-Am reportedly purchased between 2,000 and 4,000drums of spent catalyst material from refineries and chemical plants along the Houston ShipChannel and stored the drums at the MDI site. By 1988, the spent catalyst recycling operationsceased and the stored drums were abandoned on the site. On June 26, 1990, the Texas WaterCommission conducted a complaint investigation at the MDI facility. During the inspection, theinvestigator documented the presence of approximately 4,000 drums at the site, most of themseverely corroded and spilling their contents onto the ground surface.

In March of 1991, the MDI site re-opened as San Jacinto Foundry, which operated until June of1992, when operations ceased and the site became inactive. On May 20, 1992, MDI filed aChapter 7 bankruptcy petition. On May 6, 1994, the Texas Natural Resource ConservationCommission (TNRCC) cited several violations concerning the storage of approximately 5,300drums of waste material. Eight samples of the spilled drum contents were collected and theresults indicated elevated levels of arsenic, nickel, lead, and molybdenum. The MDI site wasreferred to the TNRCC Pollution Cleanup Division on December 6, 1994 [1].

From March 1995 through January 1996, salvage operations were conducted at the MDI site asapproved by the bankruptcy court. Demolition of on-site buildings and structures, initiated bythe trustee for MDI, occurred during this time. On March 31, 1995, TNRCC Region 12 staffmembers conducted an inspection of the site to determine the status of the demolition activities[2]. During the demolition activities, the City of Houston Bureau of Air Quality Controlconducted air sampling at the MDI facility. The samples were submitted to the TNRCC foranalysis for total suspended particulates and metals [2]. Buildings remaining at the site include apartially demolished brick office building with an attached brick laboratory building and abuilding used previously for the storage of low level radioactive waste. On March 14, 1995,following a communication from the United States Bankruptcy Court concerning the intent tosell certain property and equipment at the MDI site, the Texas Department of Health (TDH)Bureau of Radiation Control (BRC) inventoried and consolidated all radioactive material andequipment stored at MDI into one room of the shooting bays building. This room was lockedand sealed by TDH BRC staff [2]. Currently there are no radioactive sources on site.

Demographic Statistics
Figure 1. Demographic Statistics

In January of 1996, EPA and TNRCC collected six soil samples from inside the fenced area ofthe MDI site and from five nearby residential yards. The majority of the on-site samples werefound to be highly contaminated with heavy metals including arsenic, manganese, nickel, lead,copper, iron, and thallium [3]. Lead was measured in soil from the residential yards at concentrations ranging from 556 to 1,170 milligrams lead/kilogram soil (mg/kg) [3]. No otherconstituents were found at elevated levels in the residential yards.

In 1996, EPA, at the request of TNRCC, initiated a more comprehensive residential yardsampling plan within the MDI residential area. EPA collected 100 soil samples from yards andvacant lots and found soil lead levels ranging from 59 to 3,180 mg/kg. Soil lead concentrationsexceeded 500 mg/kg in 41 of the properties. In 1998, the TNRCC identified 48 additionalresidential properties with soil lead concentrations exceeding 500 mg/kg. The contaminated soilhas been removed from all 89 of the residential properties. The contaminated soil has beendisposed in a permitted landfill [4].

In addition to sampling soil from residential yards, TNRCC collected two 8-part composite soilsamples from the Bruce Elementary School playground and found soil lead concentrations of 59and 83 mg/kg in the two samples. These levels are representative of background concentrations. TNRCC did not find any elevated levels of metals in the soils tested on the school grounds. TNRCC collected six samples from nearby Buffalo Bayou (both upstream and downstream ofthe MDI site) and found all six contained only background concentrations of the constituentsmeasured [3].

EPA proposed placing the MDI site on the National Priorities List (NPL) on September 29, 1998,and the site was officially placed on the NPL on January 15, 1999 [5]. EPA signed a "RemovalAction Memorandum" to address the removal of 5,355 deteriorating drums of waste from the siteand 100,000 cubic yards of contaminated soil on the site. On March 10, 1999, EPA Region 6Emergency Response began stabilization efforts at the site to minimize the potential for off-sitemigration of contaminants from nearly 600 leaking drums [6]. In August 1999, the PotentiallyResponsible Party (PRP), operating under EPA oversight, began the drum removal activities. The 5,355 drums addressed in the "Removal Action Memorandum" were transported to licenseddisposal facilities along with associated debris and visually contaminated soil. Representativesof the TNRCC and EPA Superfund Programs conducted a tour of the MDI site on November 1,1999 and observed that all of the drums had been removed along with their contents [7].

Previous TDH/ATSDR Involvement

TDH's and ATSDR's involvement with MDI began in 1996 when TDH prepared a healthconsultation (Appendix B) for the site [8]. The health consultation, which was released onSeptember 30, 1997, reviewed soil sample results collected by EPA and TNRCC. The datareviewed included soil samples from the following locations: on the site, residential yards, adrainage area leading away from the site, Bruce Elementary School, and Buffalo Bayou, bothupstream and downstream of the site.

In July 1996, during the preparation of the health consultation, TDH personnel visited the site. The site was completely surrounded by a six-to-eight foot fence capped with barbed wire;however, there were gaps between locked gates through which small children could gain accessto the site. There were signs on the fence in Spanish and English warning people not to trespasson the site. TDH personnel noted that the area around the site is densely populated to the east andwest. Homes in the area were predominantly of wood frame construction on pier and beamsupport. Children were playing in the yards near the site. On the site itself, TDH personnel sawnumerous waste piles, thousands of drums, a polychlorinated biphenyls (PCB) labeledtransformer, and a pit containing waste oil. The soil itself appeared darkened, leading the staffmembers to suspect the discoloration was a result of contamination.

Based on the information available at that time, TDH and ATSDR concluded the following:

  1. The MDI site is heavily contaminated with metals of public health concern. The soil islikely contaminated from the thousands of corroding barrels of leaking material. TheMDI site itself has restricted access via a chain link fence; therefore, it is not expected that children would have direct contact with the metal contaminants on site.

  2. Soil in the drainage area directly inside and under the fence surrounding the site iscontaminated with heavy metals. Although this area is not accessible to neighborhoodchildren, it is probable that site contaminants could migrate to the area immediatelyoutside the fenced area. Lead and arsenic are of primary public health concern forchildren who may be exposed to this contaminated soil.

  3. Thallium was found at elevated levels in the drainage area. This metal can be asignificant public health concern for children or adults who may be exposed to thecontaminated soil through incidental ingestion.

  4. Lead was found at elevated levels in all five of the residential yards analyzed. It also wasfound at elevated levels in the drainage area, but was not found to be above backgroundlevels on site or in the school yard. Based on available models correlating blood leadlevels with lead in soil, children exposed to contaminated soil in the residential yards and drainage area could experience elevated blood lead levels.

  5. Other metals found to be significantly above background levels in the accessible areas ofthe drainage area and residential yards include manganese, nickel, antimony, copper, andiron. These metals typically adhere strongly to soil particles and are not readilybioavailable to humans. The type of exposure leading to adverse health effects is lesslikely than those caused by exposure to lead, arsenic, and thallium mentioned above.

  6. Off-site migration of metals found on or near the MDI site could be responsible for the elevated levels of metals such as copper, iron, antimony, and arsenic in the drainage area and residential yards, where these metals were found to be significantly above background levels.

In 1998, TDH was asked to evaluate the public health significance of the lead found in soilsamples collected at the site. In addition to soil lead data, TDH also reviewed blood lead data for36 children (ranging in age from approximately one year to 11 years) who lived in theneighborhood. The blood lead data had been collected over a period of several years (1993 to1996) by the City of Houston Health and Human Services Department.

TDH and ATSDR concluded that based on the distribution of lead in the soil as many as 46% of the properties in the neighborhood could have soil lead levels greater than 400 mg/kg, 34% could have soil lead levels greater than 500 mg/kg, and 8% could have soil lead levels greater than 1,000 mg/kg. TDH and ATSDR also reported that 22% of the children tested (all ages) and 39% of the younger children (less than 72 months of age) had blood lead levels greater than 10 micrograms lead/deciliter blood (µg/dL). The average blood lead level for the 18 children less than 72 months of age was 11 µg/dL. The report (Appendix C) suggested that this appears to be a higher than normal percentage of children with elevated blood lead levels since, "In Texas we generally find that less than 9% of the children tested have blood lead levels greater than 10 µg/dL." [9].

Health Outcome Data

In addition to the blood lead data reviewed in the previous health consultation, we were able to obtain additional blood lead data from the City of Houston Lead Hazard Prevention Program. From 1996-1999, the City of Houston Lead Hazard Prevention Program collected blood samples from 66 children, less than 80 months of age, from Bruce Elementary School for lead screening. Blood lead levels ranged from non-detect to 18.3 µg/dL with an average concentration of 5.5 µg/dL. Twelve percent of the children tested had blood lead levels greater than or equal to 10 µg/dL; approximately 25% of the children between 18 months and three years of age had blood lead levels greater than 10 µg/dL (Figure 2).

Demographics

The 1990 census data indicates that there are 7,078 housing units and 14,871 people living withina one mile radius of the site (Figure 1). Approximately 77% of the people in this area areAfrican American, 8% are White, 0.2% are American Indian or Eskimo, 1.6% are Asian, and13.3% are of "other races." Approximately 22% of the total population was identified as beingof Hispanic descent. In 1990, there were 2,029 children aged six and younger (14% of thepopulation), 2,105 adults aged 65 and older (14% of the population), and 3,234 females aged 15 to 44 (22% of the population) [10].

Bruce Elementary School 1996-1999 Blood Lead Screening
Figure 2. Bruce Elementary School 1996-1999 Blood Lead Screening


COMMUNITY HEALTH CONCERNS

To collect community health concerns, TDH staff attended several stakeholder meetings, openhouses, and public availability sessions in which individuals living in the residential area next toMDI expressed their concerns regarding their proximity to the site. The principal of BruceElementary School has provided TDH with information about historic and current concerns ofparents whose children attend the school across from the site. Additionally, TDH staff has beenin contact with TNRCC, EPA Region 6, and the City of Houston Health and Human ServicesDepartment. Below is a summary of the concerns that we received:

  1. Many homes are built on pier and beam construction, which allows space for children and pets to crawl underneath them. Does TNRCC plan to clean up the soil under the homes?

  2. What kinds of contaminants were found on and off of the MDI site?

  3. How many residential yards have been found to be contaminated?

  4. Where did the lead in the soil from the residential yards come from?

  5. What are the symptoms of lead poisoning?

  6. Could emissions from the smokestacks during the time MDI was operating cause adversehealth effects?

  7. What has been done to educate the community about the contaminants and hazards on theMDI site?

  8. What medical tests have been performed for those citizens concerned about lead toxicity?

  9. Has drinking water been affected by the site?

  10. Is it safe to eat vegetables grown in gardens from areas found to have elevated lead levels in soil?

  11. Should we be concerned about tracking the lead into our homes?

  12. Will the dust being generated during the remediation process be controlled?

  13. Is trespassing on the site a concern?

  14. Bringhurst Street often floods after it rains. Children frequently play in standing water upto two feet deep during these floods. What will be done to prevent the runoff of sitecontaminants onto the street after periods of heavy rain?

ENVIRONMENTAL CONTAMINATION / PATHWAYS ANALYSIS / PUBLIC HEALTH IMPLICATIONS

Introduction

The presence of chemical contaminants in the environment does not always result in exposure toor contact with the chemicals by people. Since chemicals only have the potential to causeadverse health effects when people actually come into contact with them, it is exposure, or thecontact that people have with the contaminants that drives the public health assessment process.

People may be exposed to chemicals in different ways; usually by breathing, eating, drinking, orcoming into contact with a substance containing the contaminant. This section reviews availabledata to determine whether contamination is present and if people in the community have been,currently are, or may in the future be exposed to contaminants from the site.

In order to categorize the ways that people could be exposed to site contaminants, we considerthe five elements of an exposure pathway: (1) a source of contamination; (2) transport through anenvironmental medium; (3) a point of exposure; (4) a plausible manner (route) for thecontaminants to get into the body; and, (5) an identifiable exposed population. For a person to beexposed to a contaminant, the exposure pathway must be completed. An exposure pathway isconsidered to be completed when all five elements in the pathway are present and exposure hasoccurred, is occurring, or could plausibly occur in the future. A potential pathway is missing atleast one of the five elements but may possibly be considered to be completed as more databecome available or as site conditions change. Eliminated pathways are missing one or more ofthe five elements and in the best estimation of the health assessor will never be completed. Completed and potential pathways for the MDI site are presented in Table 1.

Since exposure does not always result in adverse health effects, we evaluate whether theexposure could be sufficient to pose a hazard to people in the community. The factors thatinfluence whether exposure to a contaminant or contaminants could or would result in adversehealth effects include; (1) the toxicologic properties of the contaminants; (2) how much of thecontaminant the individual is exposed to; (3) how often and/or how long exposure occurs; (4) themanner in which the contaminant enters or contacts the body (breathing, eating, drinking, orskin/eye contact); and, (5) the number of contaminants to which an individual is exposed(combinations of contaminants). Once exposure occurs, characteristics such as age, sex,nutritional status, genetics, life style, and health status of the exposed individual influence howthe individual absorbs, distributes, metabolizes, and excretes the contaminant.

Initially, we evaluate the potential for adverse health effects by identifying contaminants ofconcern. We do this by comparing contaminant concentrations to health assessment comparison(HAC) values which are media specific contaminant concentrations that are used to screencontaminants for further evaluation. While exceeding a HAC value does not necessarily meanthat a contaminant represents a public health threat, it does suggest that the contaminant warrantsfurther consideration. Noncancer HAC values are called environmental media evaluation guides(EMEGs) or reference dose media evaluation guides (RMEGs) and are respectively based onATSDR's minimal risk levels (MRLs) or EPA's reference doses (RfDs). MRLs and RfDs areestimates of a daily human exposure to a contaminant that is unlikely to cause adverse non-cancer health effects. Cancer risk evaluation guides (CREGs) are based on EPA's chemicalspecific cancer slope factors and an estimated excess lifetime cancer risk of one-in-one-millionpersons exposed for a lifetime. We used standard assumptions to calculate appropriate HACvalues [11].

The public health significance of contaminants that exceed HAC values is assessed by reviewingand integrating relevant toxicological information with plausible exposure scenarios. Estimatedexposures may be compared to reported "No Observable" and "Lowest Observable" AdverseEffects Levels (NOAELs and LOAELs) and to known effect levels in humans, when available.

Table 1.

Completed and Potential Exposure Pathways for the Many Diversified Interests Site
PATHWAY NAME PRIMARY CONTAMINANTS OF CONCERN EXPOSURE PATHWAY ELEMENTS TIME CONCLUSIONS
SOURCE ENVIRONMENTAL MEDIA POINT OF EXPOSURE ROUTE OF EXPOSURE EXPOSED POPULATION
Completed Exposure Pathways
Residential soil Lead Contaminant migration from air dispersion, lead-based paint Soil/Dust Residential yards Ingestion,
Inhalation
Residents Past In the past, lead in the soil presented a public health hazard.
Present Since soil with high lead levels has been removed and replaced with non-contaminated soil, residential soil no longer poses a public health hazard.
Ambient air Chromium, Copper, Lead, Nickel Stack emissions Ambient air On site, Nearby residential neighborhood Inhalation
Ingestion
Residents,
On-site workers
Past Past exposure to contaminants from stack emissions is an indeterminate public health hazard because of insufficient information.
Iron,
Chromium
Dust from demolition activities Exposure to ambient air during demolition activities poses no apparent public health hazard because there is no evidence that people would have come into contact with contaminants often enough at concentrations that would be a public health concern.
On-site contamination Arsenic,
Possibly Asbestos
Abandoned drums, soil, landfill, waste piles, Transformers, On-site ponds, Underground storage tanks Soil/Dust,
Waste material
On site Ingestion, Dermal contact Trespassers Past Indeterminate public health hazard because of a general lack of historical exposure information.
Present
Future
No public health hazard as long as access to the site is restricted.
Potential Exposure Pathways
Surface water Site contaminants Contaminated on-site soil Floodwater On and off the site Ingestion,
Dermal contact
Residents Past
Present
Future
No apparent public health hazard. Additional data could confirm or refute this conclusion category.

Evaluation of the Soil Exposure Pathway

Residential Soil

Summary: We have concluded that prior to removal, lead in the soil from residential yards poseda public health hazard. Under site-specific conditions of exposure, chronic exposure to lead inthe soil could have had an adverse impact on the health of children. Since soil with high leadlevels has been removed, residential soil no longer poses a public health hazard.

In January 1996, EPA and TNRCC collected soil from five residential properties near the MDIsite and found all five samples to contain lead in excess of 500 mg-lead/kg-soil. In Januarythrough June of 1996, samples were collected from100 residential properties, and 40 sampleswere found to contain lead concentrations in excess of 500 mg/kg (4 of 5 properties were thesame properties previously sampled). From May through June of 1998, an additional 45properties were identified by TNRCC as having soil lead concentrations above 500 mg/kgbringing the total number of properties with soil lead concentrations greater than 500 mg/kg to89 (17 vacant lots and 69 residential yards) [4].

The highest soil lead concentration measured in a residential lot was 6,989 mg/kg. Thirteen properties (2 vacant lots and 11 residences) had soil lead concentrations between 1,000 and 1,500mg/kg. Eleven properties (three vacant lots, one garden area, and seven residential properties)had soil lead concentrations above 1,500 mg/kg [4].

Preschool-age children and fetuses are considered the most vulnerable segments of thepopulation for exposure to lead. This increased vulnerability results from a combination offactors which include: (1) the developing nervous system of fetuses and neonates are moresusceptible to the neurotoxic effects of lead; (2) young children are more likely to play in dirt andto place their hands and other objects in their mouths, increasing the opportunity for soilingestion; and, (3) the efficiency of lead absorption from the gastrointestinal tract is greater inchildren than in adults.

Chronic exposure to low lead levels has been shown to cause subtle effects on the centralnervous system which can manifest as deficits in intelligence, behavior, and school performance[12]. Recent information indicates that children with blood lead levels as low as 10 g/dL candevelop neurological and cognitive deficits [13]. Available evidence is not sufficient todetermine whether lead-associated deficits are irreversible [14].

Although no threshold level for adverse health effects has been established, evidence suggeststhat adverse effects occur at blood lead levels at least as low as 10 g/dL. The Centers forDisease Control and Prevention (CDC) has determined that a blood lead level greater than orequal to 10 g/dL in children indicates excessive lead absorption and constitutes the grounds forintervention. The 10 g/dL level is based on observations of enzymatic abnormalities in the redblood cells at blood levels below 25 g/dL and observations of neurologic and cognitivedysfunction in children with blood lead levels between 10 g/dL and 15 g/dL [14].

There are a number of studies available relating blood lead levels in children to levels of lead inthe environment. In general, blood lead levels may rise 3 to7 g/dL for every 1,000 mg/kgincrease in soil or dust lead concentration. Regression models for the correlation between bloodlead levels and soil lead levels predict that soil lead concentrations between approximately 500and 1000 mg/kg would result in blood lead levels below 10 g/dL [15]. Eighty-nine residentialproperties near the MDI site were identified as having soil lead concentrations greater than 500mg/kg. Based on available models, chronic exposure to lead at the concentrations measured atmany of these residences could result in elevated blood lead levels in small children. Althoughthe data at this site were not collected in a manner suitable to investigate the soil-lead and blood-lead relationship, available blood lead data does indicate that a large percentage of the youngerchildren tested in this neighborhood had blood lead levels greater than 10 g/dL [9].

The 89 properties identified as having soil lead concentrations greater than 500 mg/kg have beenremediated by TNRCC [4] and the contaminated soil was removed and disposed of in apermitted landfill. The yards were backfilled with clean soil and new grass was planted. Currently, soil in the residential yards does not present a public health hazard.

Arsenic was found in soil from one residential yard at a concentration of 24.4 mg/kg, which isslightly greater than the HAC value for children (20 mg/kg), which is based on an oral referencedose (RfD) of 0.0003 mg/kg/day. Acceptable values for the RfD, which is based on an increasedincidence of hyperpigmentation and keratosis that increases with dose and age, range from0.0001 to 0.0008 mg/kg/day [16]. We would not expect exposure to soil containing arsenic at aconcentration of 24.4 mg/kg to result in observable adverse health effects.

There has been some interest in potential hazards associated with exposure to lead in soil underthe homes. Since the soil under the homes has not been sampled, it is impossible toquantitatively evaluate this pathway; however, for several reasons we would not anticipate this tobe a significant source of exposure. To a large extent, the amount of lead that gets into a child'sbody depends on the amount of lead in the soil and the frequency of contact with the soil. If thelead in the soil resulted from air deposition, we would expect less lead to have been depositedunderneath the homes. Thus, the amount of lead under the homes would be less that the amountin the yards. In general, based on possible reasonable exposure scenarios we would notanticipate that exposure to the soil under the homes to be as frequent as exposure to soil in theyards. Thus, even if it contained lead concentrations comparable to those in the yards, we wouldnot expect exposure to be of sufficient frequency, magnitude, and duration to pose a publichealth threat. Additional data would be required to confirm or further support this conclusion;however, based upon our best professional judgement we would conclude that the soil under thehomes poses no apparent public health hazard.

Evaluation of the Air Exposure Pathway

Stack Emissions

Summary: We have concluded that past exposure to site contaminants from stack emissions is anindeterminate public health hazard. Although there is sufficient indirect evidence to suggest thatpast air emissions from the site may have reached beyond the confines of the site into theresidential areas, we could not quantify, with any degree of certainty, the public healthsignificance of these emissions. The contaminants that have been implicated with possible airemissions include chromium, copper, lead, and nickel.

Historical ambient air data for the period of time during which the facility was active were notavailable; however, the TNRCC Air Program files for the TESCO facility and later San JacintoFoundry contain frequent Texas Clean Air Act compliance inspections and complaintinvestigations conducted at the facility from January 1982 through October 1991. Violationsdocumented during this period primarily involve visible emissions of particulate matter from thestacks and vents of the facility [2]. In addition, there have been confirmed and unconfirmedcomplaints of migrating odors and air pollution from the MDI site into the residentialneighborhood and at Bruce Elementary School [17]. According to the HRS documentationrecord, the analytical results for composite surface soil samples collected from the residentialarea north and northwest of the site (the prevailing wind direction) were consistent withcontaminant migration from the site via air dispersion. The predominant heavy metals thatqualified as observed contamination included chromium, copper, lead, and nickel. No otherpotential industrial sources were identified in the area that could have contributed to the presenceof these substances in the residential yards. Because of the general lack of historical ambient airdata we could not determine with any degree of certainty the public health significance ofexposures to possible past air emissions.

Demolition Activities

Summary: We have concluded that exposure to contaminants in the air during the demolitionactivities at the site posed no apparent public health hazard. Although some contaminants weredetected in the air, there is no evidence that people would have come into contact with enough ofthe contaminants often enough or long enough to result in adverse health effects.

We were able to locate ambient air data collected by TNRCC in 1995 during the demolition ofseveral foundry buildings on the site. TNRCC collected ambient air samples both upwind anddownwind of MDI. Samples were analyzed for total suspended particles, arsenic, barium,cadmium, chromium, iron, lead, selenium, and thallium. Total suspended particles werecompared to the TNRCC Regulation I standard, and lead was compared to the quarterly NationalAmbient Air Quality Standard. The remaining metals were compared to TNRCC's EffectsScreening Levels (ESLs). ESLs are used to evaluate the potential for effects to occur as a resultof exposure to concentrations of constituents in air. ESLs are based on data concerning healtheffects, odor nuisance potential, effects with respect to vegetation, or corrosion effects. They arenot ambient air standards. If predicted or measured airborne levels of a constituent do not exceedthe effects screening level, adverse health effects would not be expected to result. Ambientlevels of constituents in air exceeding the effects screening levels do not necessarily indicate aproblem; however they are considered a trigger for a more in-depth review. Health-based ESLsare set to provide a margin of safety, and are well below levels at which adverse health effectsare expected [18].

Downwind of the site, total suspended particles (307 micrograms per cubic meter or µg/m3), arsenic (<0.1 µg/m3), barium (0.3 µg/m3), cadmium (<0.005 µg/m3), selenium (<0.1 µg/m3), and thallium (<0.1 µg/m3) were measured below their respective ESLs. The downwind concentration of iron (93 µg/m3) was almost two times the ESL of 50 µg/m3. The downwind concentration of total chromium (0.48 µg/m3) was four times the ESL for hexavalent chromium (0.1 µg/m3) but below the ESL for trivalent chromium (1.0 µg/m3). The chromium generated from foundry operations is most likely to be trivalent chromium and not the more toxic hexavalent form [18]. These measured concentrations only represent conditions during demolition activities which are not expected to continue for an extended period of time. Limited, short-term exposure to these contaminants at the reported concentrations would not be expected to result in adverse health effects.

Evaluation of the On-Site Contamination Exposure Pathway

Summary: We have concluded that contaminants on the site do not currently pose a public healthhazard. Access to the site is restricted and there is no evidence that exposures currently areoccurring. There are several waste source areas and/or areas of observed contamination wherepeople could come into contact with contaminated media. Access to the site was not alwayscompletely restricted and, in the past, trespassers could have come into contact with sitecontaminants. Arsenic, lead, and a white fibrous material thought to be asbestos are the primarycontaminants of concern found on the site. Although there is a general lack of historicalexposure information we have concluded that under some site-specific conditions, past exposureto some of the contaminants by trespassers could have posed a public health hazard. Due toinsufficient exposure information, we have concluded that past exposure to on-site contaminantsis an indeterminate public health hazard.

Spilled Drum Waste and Contaminated Soil

Contaminated soil at the MDI site has been reported to include oil-contaminated soil, soilcontaminated with spilled drum waste, soil with foundry sand and slag, and soil stained withunknown substances.

In 1994, it was reported that 4,464 drums were located on the site, 4,179 of which were identifiedas containing spent refinery catalyst material. The remaining drums were reported to containvarious types of oils, grease, baghouse waste, core wash mixture, and other hazardous waste [3]. Results from eight (8) samples of spilled drum contents were collected and analyzed. The resultsindicated elevated levels of arsenic (non-detect to 2,340 mg/kg), nickel (223 to 43,900 mg/kg),lead (non-detect up to 1,840 mg/kg), and molybdenum (28,700 to 74,800 mg/kg). A soil samplefrom one of the drum storage areas contained arsenic (28.4 mg/kg), chromium(197 mg/kg),cobalt (122 mg/kg), iron (74,144 mg/kg), nickel (4,430 mg/kg), and selenium (3 mg/kg) [3].

In January of 1996, EPA collected six on-site soil samples and three background soil samples. The maximum on-site concentrations of the following contaminants exceeded health-basedcomparison values: lead (1,880 mg/kg), arsenic (116 mg/kg), manganese (28,000 mg/kg), thallium (23.4 mg/kg), and nickel (4,430 mg/kg). On-site contaminants exceeding backgroundlevels by at least three times include copper (940 mg/kg) and iron (327,000 mg/kg) [3].

In September of 1992, the Texas Water Commission, predecessor of TNRCC, documented that55-gallon drums were buried in the on-site landfill. Some of the drums were reported to beleaking a black tar-like material. One soil sample obtained during the Site Screening Inspection(SSI) indicated the presence of arsenic (20.5 mg/kg), chromium (936 mg/kg), cobalt (22.8mg/kg), copper (448 mg/kg), iron (199,000 mg/kg), magnesium (6,300 mg/kg), manganese(6,000 mg/kg), nickel (725 mg/kg), silver (0.83 mg/kg), selenium (6.9 mg/kg), and thallium (5.6mg/kg) [3].

Waste Piles, Transformers, and On-Site Ponds

There are numerous waste piles throughout the site consisting of foundry sand, demolitiondebris, and scrap metal. A white, fibrous material lining the inside of the furnaces prior to theirbeing demolished was observed on the site. A similar white fibrous material thought to beasbestos has been observed scattered around the site and in some of the waste piles [3].

EPA documented 19 PCB capacitors in service and an undisclosed number of PCB transformerson the site during an early site inspection. During the SSI, the site visit team noted one largemelt transformer and several small capacitors. There was a label on the large melt transformerindicating that it contained PCBs. In 1994, a private firm contracted by EPA (TERA, Inc.),reported three large melt transformers, three unspecified transformers, two drums of transformeroil, one melt transformer pit with approximately 17 barrels of oily waste, and an unspecifiednumber of oil-filled capacitors on the site. During the EPA/TNRCC site tour of November 1,1999, only one large melt transformer was observed at the northwest corner of the site.

There are two intermittent ponds on the site; one near the center of the property and the othernear the southeast corner. During the SSI, the pond near the southeast corner of the propertycontained a large volume of some type of oil. A laboratory analysis of this oil indicated thepresence of hexadecane (1,630 mg/kg), heptadecane (1,400 mg/kg), octadecane (1,450 mg/kg),eicosane (1,800 mg/kg), and heneicosane (1,790 mg/kg) [3]. During the EPA/TNRCC site tourof November 1, 1999, both ponds were observed to be dry.

Five of the contaminants found in the soil and spilled drum waste (arsenic, nickel, manganese,thallium, and lead) exceeded health-based comparison values for children (Appendix B). Twoadditional contaminants (copper and iron), for which comparison values are not available, werefound at concentrations significantly above background levels. Because the site is currentlysurrounded by a six-to-eight foot chain-link fence capped with barbed wire, access to the site isrestricted and exposure to contaminants on the site is unlikely.

In the past, the metal chain-link fence was in poor condition and there were several gaps in thefencing mesh through which children could enter. Thus, children could have trespassed on thesite. Because of the nature of trespasser exposure scenarios, it would be difficult to determinewith any degree of certainty the level of health hazard associated with the exposures. For mosttrespasser scenarios, contact with site contaminants is likely to be infrequent. We would notexpect such infrequent contact to result in adverse health effects.

For some contaminants, infrequent exposure to high concentrations could be sufficient to resultin adverse health effects. This is particularly true for children who exhibit pica behavior. It hasrecently been suggested that while any individual child may exhibit pica behavior infrequently,pica behavior may occur in a sizable number of children throughout the year [19]. Calabreseestimated that approximately 62% of children will ingest more than one (1) gram of soil 1-2days/year, while 42% and 33% of children will ingest more than five (5) and 10 grams of soil 1-2days per year, respectively.

Arsenic

For arsenic, most of the reported Lowest Observable Adverse Effects Level (LOAEL) values foracute exposure are about one (1) milligram arsenic per kilogram of body weight per day(mg/kg/day); however, since these values are derived mainly from case reports of fatal or near-fatal exposures, it is possible that lower acute doses also could produce acute arsenic toxicity. The lowest reported LOAEL for serious effects (sinus tachycardia) from acute exposure (once) is0.02 mg/kg/day [20]. To explore the possibility that infrequent pica behavior could result inexcess exposure to arsenic, we estimated that infrequent (1-2 times per year) pica behavior bychildren could result in acute arsenic exposure doses that are greater than the reported acuteLOAELs for this contaminant. We have concluded that past exposure to arsenic on the site couldhave posed a public health hazard; however, due to the absence of site-specific exposureinformation, this has been classified as an indeterminate public health hazard.

White Fibrous Material

The white fibrous material observed scattered around the site is thought to be asbestos; however,sample analysis of this material was not available for our review. We also are not aware of thecondition of this material (i.e., whether it is friable). Exposure to friable asbestos fibers is knownto create serious disease conditions in man. Asbestos is a human carcinogen linked to lungcancer, pleural mesothelioma, peritoneal mesothelioma, and at a lesser frequency,gastrointestinal cancers. Asbestos also may cause a chronic degenerative respiratory diseasecalled asbestosis. This respiratory disease scars the lungs reducing their ability to adequatelyprovide oxygen to the body. Lung cancer starts within the respiratory tissues, and mesothelialcancers grow from the thin membranes that surround the lung or the abdominal cavities. Inhaling asbestos into the lungs is the exposure route of greatest concern. Some of the asbestosfibers reaching the lungs are eliminated in exhaled air and others are caught by mucus and smallhairs (cilia) in the upper parts of the lungs. The respirable fibers reaching the deepest airpassages of the lungs can produce the greatest damage. The digestive system can be affected byasbestos fibers from food, drinking water, and mucus cleared from the lungs. These fibers maypenetrate the cells that line the digestive system and produce cellular changes causing cancer. Asbestos-related lung cancer and mesothelioma, which are usually fatal, do not appearimmediately, but may develop 20 to 50 years after exposure [21].

The carcinogenic risk model for asbestos is a non-threshold linear model in which there is nodose below which an increased lifetime risk of cancer does not exist. This current healthevidence holds that there is no safe of level of asbestos exposure. Supporting this, humanepidemiologic evidence documents that even low-level exposures to these fibers have causedasbestos-related disease. The commercially important fiber types, like amosite, crocidolite, andcrysotile asbestos, may have some differences in potency or specificity to produce specificcancer or disease conditions. Fiber length and length-to-diameter relationships also may haveeffects on ability of the fibers to cause disease. For purposes of protecting public health,minimizing the exposure to any type or size of asbestos fiber is a prudent course of action [21,22]. If the material is asbestos and it is in a form that is both friable and attractive to children,acute exposure to the material could result in an increased risk for the development of disease. Because of the unknowns relating to the exact nature of the material and the variability of factorsrelated to estimating potential exposure to the material by children who may have trespassed onthe site, we have concluded that this remains an indeterminate public health hazard.

Evaluation of the Surface Water Exposure Pathway

Summary: We have concluded that exposure to surface water runoff from the site poses noapparent public health hazard. Additional data could confirm or refute this conclusion category. Although data illustrating the concentration of contaminants in the surface water runoff were notavailable, the infrequent nature of exposure via this pathway and the dilution potential of thelarge volumes of rainwater that enter the street, it is unlikely that exposure to contaminants inthe surface water runoff would result in adverse health outcomes.

Community members have expressed concern about past, current, and future exposure to sitecontaminants in storm water runoff from the site onto neighborhood yards, the streets adjacent tothe site, and the playground of Bruce Elementary School. High levels of contaminants such aslead and arsenic have been found on the site; however, we are not aware of any sampling ofsurface water to determine whether contaminants are being transported off the site via thismedium. Children reportedly wade and play in standing water after rainstorms. If surface waterwere contaminated, human exposure could occur by incidental ingestion while playing in thewater or by dermal contact with contaminants in the water. However, given the infrequent natureof such events and the large volume of water that likely would dilute the runoff, we would notanticipate that exposure to this media would result in adverse health outcomes. Additional dataare needed to confirm or further support this conclusion.

Physical and Other Hazards

Currently, all 5,300 of the leaking, rusty barrels, associated debris, and visually contaminatedsoil have been transported to permitted disposal facilities [7]. The buildings remaining at the siteare partially demolished and present a danger from structural instability. There are two large pitson the site that are not readily visible which contain an unknown liquid [3]. There are brokenbottles, rusty, sharp metal pieces, slag, and other waste materials throughout the site. Currently, the site is fully fenced and is not accessible to the public.


ATSDR'S CHILD HEALTH INITIATIVE

The TDH has prepared this assessment under a Cooperative Agreement with the Agency forToxic Substances and Disease Registry (ATSDR). TDH has included the following informationin accordance with the ATSDR's Child Health Initiative.

ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants andchildren demand special emphasis in communities faced with contamination of their water, soil,air, or food. Children are at greater risk than adults from certain kinds of exposures to hazardoussubstances emitted from waste sites and emergency events. They are more likely to be exposedbecause they play outdoors and they often bring food into contaminated areas. They are shorterthan adults, which means they breathe dust, soil, and heavy vapors close to the ground. Childrenalso are smaller, resulting in higher doses of chemical exposure per body weight. Thedeveloping body systems of children can sustain permanent damage if toxic exposures occurduring critical growth stages. Most importantly, children depend completely on adults for riskidentification and management decisions, housing decisions, and access to medical care.

TDH evaluated the potential for children living in the vicinity of the MDI site to be exposed tosite contaminants at levels of health concern. TDH identified situations in which children havebeen or could be exposed to site contaminants.


COMMUNITY HEALTH CONCERNS EVALUATION

  1. Many homes are built on pier and beam construction which allows space for children and pets to crawl underneath them. Does the TNRCC plan to remediate soil under thehomes?
  2. We are not aware of any plans by TNRCC to remediate the soil under the homes;however, we also are not aware of any samples taken from beneath the homes. Thus, atpresent, the claim that the soil under the homes contains lead at levels of public healthsignificance is speculation. We would not expect this to be a significant exposurepathway because the air deposition of lead under the homes likely is low, and plausibleexposure scenarios would be infrequent.

  3. What kinds of contaminants were found on and off of the MDI site?
  4. Lead, arsenic, nickel, manganese, iron, copper, and thallium were found on the MDI site. Off the site, lead was found in soil from residential yards.

  5. How many residential yards have been found to be contaminated?
  6. Eighty-nine properties in the area (20 vacant lots, 45 entire yards, and 24 partial yards)were found to have lead levels above 500 mg/kg. The contaminated soil from theseproperties has been removed and replaced with uncontaminated soil.

  7. Where did the lead in soil in these properties come from?
  8. Operations at the MDI site may have contributed to the lead found in the soil; however,prior to the 1970's, house paint and car exhaust also may have been contributors.

  9. What are the symptoms of lead poisoning?
  10. Preschool-age children and fetuses are considered the most vulnerable segments of thepopulation for exposure to lead. Chronic exposure to low lead levels has been shown tocause subtle effects on the central nervous system which can manifest in deficits inintelligence, behavior, and school performance.

    Based on the levels of lead found in the soil, we would not anticipate there to have beennoticeable adverse health outcomes. In some instances, the types of adverse healtheffects associated with the types of exposures possible at this site might be picked up bysensitive neurologic or cognitive function tests (see pages 11-12 for a completetoxicological discussion on lead).

  11. Could exposure to emissions from smokestacks during the time MDI was operating causeadverse health effects?
  12. From 1982 to 1991, the TNRCC investigated several complaints primarily involvingvisible emissions of particulate matter from the stacks and vents from the facility. TheTNRCC Air Program files for the TESCO facility and later San Jacinto Foundry, recordsfrequent Texas Clean Air Act compliance inspections and complaint investigationsconducted at the facility from January 1982 through October 1991. Violationsdocumented during this period primarily involve visible emissions of particulate matterfrom the stacks and vents of the facility. We do not have any information on the specificcontaminants known to have been emitted from smokestacks on the site. Since pastexposure levels cannot be determined, it is difficult to know whether adverse healtheffects occurring in individuals are the result of past exposures to emissions coming fromthe site. Many of the adverse health effects associated with exposure to the types of contaminants that may have been in the air in the past are subtle and difficult to measureand can be associated with many factors.

  13. What has been done to educate the community about the contaminants and hazards onthe MDI site?
  14. Numerous open houses and community meetings have been held at Bruce ElementarySchool with many agencies present (TDH, TNRCC, EPA, City of Houston) to answerquestions and distribute informational pamphlets. There are warning signs posted on thefence surrounding the MDI site stating that this is a contaminated area and no trespassingis allowed. A TDH toxicologist talked to more than 450 students of Bruce Elementary ingroups ranging from kindergarten to sixth grade about the dangers of lead and ways tolessen risk of exposure. In March 1999, TDH, TNRCC, EPA, and the City of Houstonsponsored a "Health Fair"at Bruce Elementary School. Agency representatives talked tostudents about staying off the MDI site and distributed a pamphlet to all the studentstitled, "Keep Out!, The TESCO/MDI site is dangerous."

  15. What medical tests have been performed for those citizens concerned about lead toxicity?
  16. At several of the community meetings and open houses held at Bruce Elementary School,the City of Houston Health and Human Services Department has been present with nursesavailable to take blood samples for lead testing. Parents of children with elevated levelswere informed of the results by the City of Houston Health Department.

  17. Has drinking water been affected by the site?
  18. No. Drinking water is supplied by the City of Houston and is not affected by sitecontaminants. Drinking water lines do not run under the site [1]. If there is a break in thewater main, the pressure inside the line would ensure that contaminants do not get intothe water. While it is possible for a very small amount of soil to enter lines during therepair process, we would not anticipate health risks associated with this pathway. Once adamaged water line is repaired, the city flushes the line with clean water as a furtherprecaution.

  19. Is it safe to eat vegetables grown in gardens around homes found to have elevated leadlevels in soil?
  20. Lead binds strongly to soil particles; therefore, it is only taken up by plants in minoramounts. The primary concern with respect to vegetable ingestion would be adherence ofcontaminated soils to the surface of vegetables. While we would no longer expect lead tobe a concern since the removal action has been completed in the residential area, we advise individuals to always wash and clean their vegetables as a precautionary measure.

  21. Should we be concerned about tracking the lead into our homes?
  22. Although household dust was not sampled, soil lead levels in the yards were not highenough to create a significant risk of exposure to lead in household dust. Currently,contaminated soil from all 89 residential yards has been removed.

  23. Will the dust being generated during the remediation process be controlled?
  24. As the lead agency conducting the remediation, TNRCC requires the implementation ofdust control and monitoring procedures during remediation to prevent adverse impacts topersons inside and outside of the remediation area.

  25. Is trespassing on the site a concern?
  26. A six-foot fence topped with barbed wire surrounds the entire MDI site. However, therehave been instances of children cutting or climbing the fence to enter the site illegally.Trespassing is a concern in terms of physical and chemical hazards on the site. There areongoing efforts between TDH, EPA, and TNRCC to warn citizens, particularly parentsand children, of the need to avoid the site. Residents have requested increased policepatrols in the area to discourage future trespassing on the site.

  27. Bringhurst Street often floods after rains and children frequently play in standing waterup to two feet deep during these floods. What will be done to prevent the runoff of sitecontaminants onto this street after periods of heavy rain?
  28. It is not known whether site contaminants are carried off the site into the adjacent streetwith rainwater. Part of the Superfund process includes a "Remedial Investigation" duringwhich TNRCC will collect rainwater samples in streets adjacent to MDI for analysis ofsite contaminants. TDH will be available to evaluate these data to determine whetherexposure to the water presents a public health threat. TNRCC has the authority toimplement measures to prevent or minimize runoff of site contaminants by rain if it isdeemed necessary.


CONCLUSIONS

  1. In the past, lead levels in soil from many of the residential yards exceeded 500 mg/kg and posed a public health hazard to small children who frequently played in those yards by adding to their overall lead exposure. Blood lead data collected from 1996-1999 by the City of Houston Lead Hazard Prevention Program indicate that a high percent (25%) of young children (1 to 3 years of age) had blood lead levels greater than 10 µg/dL. In 1999, all soil containing more than 500 mg-lead/kg-soil was removed and replaced with clean fill. Currently, residential soil does not pose a public health hazard.

  2. There is sufficient evidence to suggest that past air emissions from the facility may have reached beyond the confines of the site boundaries into the surrounding neighborhoods. Because we could not quantify, with any degree of certainty, the public health significance of these emissions, we have concluded that past exposure to contaminants in the air, during the time the facility was active, is an indeterminate public health hazard.

  3. During the demolition activities some contaminants were found in the ambient air; however, there is no evidence that people would have come into contact with enough of the contaminants often enough or long enough to experience adverse health effects. We have concluded that exposure to site contaminants in the air during the demolition activities posed no apparent public health hazard.

  4. In the past, when access to the site was not completely restricted, trespassers could have come into contact with site contaminants on an infrequent basis. Under some site-specific exposure conditions, acute exposure to some of the contaminants could have posed a public health hazard. Because of insufficient information we have concluded that past exposure to contaminants on the site is an indeterminate public health hazard. Since access to the site is currently restricted, exposure to site contaminants is unlikely. Thus, we have concluded that as long as access is restricted the on-site contamination poses no public health hazard.

  5. While it is possible for site contaminants to be carried off the site in storm water runoff, we would not expect the concentrations of contaminants in the water to be of sufficient magnitude to pose a public health threat to people who may come into contact with the water. While we have concluded that exposure to site contaminants via this pathway poses no apparent public health hazard. Additional data could confirm or refute this conclusion category.

RECOMMENDATIONS

  1. Maintain the institutional controls that restrict access to the site.

  2. The potential for migration of site contaminants off the site via storm water runoff shouldbe evaluated and the potential public health implications of contact with the water should be determined.

  3. Actions to advise residents, particularly children, of the dangers of trespassing onto the MDI site should continue.

PUBLIC HEALTH ACTIONS

  1. ATSDR and TDH will coordinate with state and federal environmental agencies to ensure that access to the site continues to be restricted.

  2. ATSDR and TDH will coordinate with state and federal environmental agencies toevaluate the potential for exposure to site contaminants in storm water runoff.

  3. ATSDR and TDH will continue to work with state and federal environmental agenciesand local health agencies to inform and educate the public about the dangers oftrespassing on the MDI site.

REFERENCES

  1. Texas Natural Resource Conservation Commission, Interoffice Memo, June 25, 1998. From Daniel Benson to Commissioners, Jeff Saitas, Executive Director. Subject - DocketNo. 98-0611-SPF: Executive summary for consideration of a 361.91 order authorizingimmediate removal actions with the MDI residential area in Houston.

  2. Texas Natural Resource Conservation Commission and U.S. Environmental ProtectionAgency, July 1996. Screening Site Inspection Report. Many Diversified Interests Site,Houston, Texas TXD008083404.

  3. Texas Natural Resource Conservation Commission, 1999. Expanded Site InspectionReport. Volume I of II, for Many Diversified Interests Site, Houston, Harris County,Texas. Prepared in cooperation with the U.S. EPA.

  4. TNRCC, Texas Natural Resource Conservation Commission, News Release, June 1,1999. TNRCC Completes MDI Residential Clean-Up.

  5. Environmental Protection Agency, National Priorities List, 1999. ComprehensiveEnvironmental Response, Compensation, and Liability Act (CERLA). Wash. D.C.

  6. Environmental Protection Agency, Many Diversified Interests, Inc. Site Update. May17, 1999.

  7. Environmental Protection Agency, Many Diversified Interests, Inc. Site Update. Nov.1999.

  8. Agency for Toxic Substance and Disease Registry. Health Consultation - ManyDiversified Interests, Inc., Houston, Harris County, Texas. CERCLIS NO.TXD008083404, September 30, 1997.

  9. Agency for Toxic Substance and Disease Registry. Health Consultation - ExposureInvestigation, Many Diversified Interests, Inc., Houston, Harris County, Texas. CERCLIS NO. TXD008083404, November 17, 1998.

  10. U.S. Census Bureau. Census of the population. Demographics Statistics Source: 1990U.S. Census. U.S. Government Printing Office, Washington, D.C., 1985.

  11. Agency for Toxic Substance and Disease Registry. ATSDR Public Health AssessmentGuidance Manual. Lewis Publishers, 1992.

  12. Needleman HL, Gunnoe C, Leviton A, et al., 1979. Deficits in psychologic andclassroom performance of children with elevated dentine lead levels. New EnglandJournal of Medicine 1979; 300:689-95.

  13. Bellinger D, Sloman J, Leviton A, Rabinowitzm, Needleman H, Waternaux C., 1991. Low-level exposure and children's cognitive function in the preschool years. Pediatrics1991. 87:219-27.

  14. CDC, 1991. Centers for Disease Control. Preventing Lead Poisoning in Young Children,A Statement by the CDC U.S. Department of Health and Human Services, Public HealthService, October 1991.

  15. Schilling R, Bain RP, 1989. Prediction of children's blood lead levels on the basis ofhousehold specific lead levels. American Journal of Epidemiology; 128(1):197-205.

  16. Tseng, W.P., Chu, H., How, S., Fong, J., Lin, C., Yeh, S. 1968. Prevalence of SkinCancer in an Endemic Area of Chronic Arsenism in Taiwan. J.Natl. Cancer Institute. 40:453-463.

  17. HRS Documentation Record. September 1998. Many Diversified Interests, Inc. Houston, Texas, Cerclis ID Number: TX008083404. Prepared for the U.S.Environmental Protection Agency by Ecology and Environment, Inc. SuperfundTechnical Assessment and Response Team, Region 6.

  18. Texas Natural Resource Conservation Commission, Interoffice Memo, Oct. 23, 1995. From Janet Pichette to Allen Parker, Region 12, Houston. Subject - ToxicologicalEvaluation of Ambient Air Sampling for Total Suspended Particulate and Metal in theVicinity of the San Jacinto Foundry.

  19. Calabrese, E.J., Stanek, E.J., James, R.C., and Roberts, S.M. Soil Ingestion: A concernfor acute toxicity in children. Environ. Health Perspect. 105: 1354-1358 (1997).

  20. Cullen, NM., Wolf, LR., St. Clair, D.. 1995. Pediatric arsenic ingestion. Am J EmergMed 13(4):432-435.

  21. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Asbestos,Atlanta: ATSDR, August 1995.

  22. U.S. Environmental Protection Agency. Asbestos: Manufacture, Importation,Processing, and Distribution in Commerce Prohibitions; Final Rule. Federal Register,Part III, 54:29460-29471. July 12,1989.

REFERENCES REVIEWED BUT NOT CITED

  1. ATSDR, 1988. Agency for Toxic Substances and Disease Registry. The nature andextent of lead poisoning in children in the United States: a report to Congress. Atlanta, GA.

  2. Hernberg S., Nikkanen J., et. al. Delta aminolevelinic acid dehydrase as a measure oflead exposure. Archives of Environmental Health 1970; 21:140-5.

  3. IRIS, 1996. Integrated Risk Information System. U.S. Environmental ProtectionAgency, Office of Health and Environmental Assessment, Environmental Criteria andAssessment Office. Cincinnati, OH.

  4. Agency for Toxic Substances and Disease Registry. Toxicological profile for arsenic. Atlanta: ATSDR, April 1993

  5. Agency for Toxic Substances and Disease Registry. Toxicological profile for manganeseand compounds. Atlanta: ATSDR, July 1992.

  6. Agency for Toxic Substances and Disease Registry. Toxicological profile for nickel(draft). Atlanta: ATSDR, Feb. 1996.

  7. Agency for Toxic Substances and Disease Registry. Toxicological profile for thallium. Atlanta: ATSDR, July 1992.

  8. Agency for Toxic Substances and Disease Registry. Toxicological profile for copper.Atlanta: ATSDR, Dec. 1990.

  9. Casarett and Doull, 1986. Toxicology. The Basic Science of Poisons, third edition. Macmillan Publishing Co., New York.

PREPARERS OF THE REPORT

Texas Department of Health

Lisa R. Williams, M.S.
Toxicologist
Health Risk Assessment and Toxicology Program

John F. Villanacci, Ph.D.
Director
Health Risk Assessment and Toxicology Program

Susan L. Prosperie, M.S., R.S.
Environmental Specialist
Health Risk Assessment and Toxicology Program

Dixie Davis
Administrative Technician
Health Risk Assessment and Toxicology Program


ATSDR REGIONAL REPRESENTATIVE

George Pettigrew, P.E.
Senior Regional Representative
ATSDR - Region 6


ATSDR TECHNICAL PROJECT OFFICE
R

Alan Yarbrough, M.S.
Environmental Health Scientist
State Programs Section
Superfund Site Assessment Branch
Division of Health Assessment and Consultation


CERTIFICATION

This Public Health Assessment was prepared by the Texas Department of Health under acooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the Public Health Assessment was initiated.

Alan W. Yarbrough
Technical Project Officer, SPS, SSAB, DHAC, ATSDR


The Division of Health Assessment and Consultation, ATSDR, has reviewed this Public Health Assessment and concurs with its findings.

Richard Gillig
Chief, State Programs Section, SSAB, DHAC, ATSDR


APPENDICES

APPENDIX A:

ACRONYMS AND ABBREVIATIONS
ATSDR Agency for Toxic Substances and Disease Registry
BRC Bureau of Radiation Control
CERCLA Comprehensive Environmental Response, Compensation and Liability Act of 1990
CREG Carcinogenic Risk Evaluation Guide
EMEG Environmental Media Evaluation Guide
EPA U.S. Environmental Protection Agency
ESL Effects Screening Level
HAC Health Assessment Comparison Value
IQ Intelligence Quotient
LOAEL Lowest Observable Adverse Effects Level
mg/kg Milligrams per Kilogram (equal to parts per million)
mg/kg/day Milligrams per Kilogram per Day
MRL Minimal Risk Level
NOAEL No Observable Adverse Effects Level
NPL National Priorities List
PCB Polychlorinated Biphenyls
PHA Public Health Assessment
RfD Reference Dose
RMEG Reference Dose-based Media Evaluation Guide
SARA 1986 Superfund Amendments and Reauthorization Act
TDH Texas Department of Health
TNRCC Texas Natural Resource Conservation Commission
g/dL Micrograms per Deciliter
g/kg Micrograms per Kilogram (equal to parts per billion)
g/L Micrograms per Liter
g/m3 Micrograms per Cubic Meter of air


APPENDIX B: HEALTH CONSULTATION, SEPTEMBER 30, 1997

Click here to view Appendix B


APPENDIX C: HEALTH CONSULTATION - EXPOSURE INVESTIGATION, NOVEMBER 17, 1998

Click here to view Appendix C



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