PUBLIC HEALTH ASSESSMENT
DEER PARK, HARRIS COUNTY, TEXAS
The Agency for Toxic Substances and Disease Registry (ATSDR) was established by theComprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. Popularly known as the "Superfund" law, this act also authorized the U.S. EnvironmentalProtection Agency (EPA) to conduct cleanup activities at hazardous waste sites, and to compile aNational Priorities List (NPL) - a list of sites considered hazardous to public health. Anamendment to CERCLA, the 1986 Superfund Amendments and Reauthorization Act (SARA),directed ATSDR to prepare a Public Health Assessment (PHA) for each NPL site.
Three types of information are used in conducting a PHA, (1) environmental data, (2) communityhealth concerns, and (3) health outcome data. The environmental data are reviewed to determinewhether community members might be exposed to hazardous materials from the NPL site. Ifpeople are being exposed to these chemicals, ATSDR will determine whether the exposures are at levels that might cause harm. Community health concerns are collected to determine whetherhealth concerns raised by community members could be related to chemicals released from theNPL site. If community members raise concerns about specific diseases in the community,health outcome data (information from state and local databases or health care providers) can beused to address those concerns. Finally, if ATSDR finds that harmful exposures have occurred,health outcome data can be used to determine if illnesses are occurring which could be associatedwith the hazardous chemicals released from the NPL site.
ATSDR and the Texas Department of Health (TDH) have prepared this PHA for the PatrickBayou NPL site under the authority of the Interagency Cooperative Agreement between ATSDRand the TDH. This PHA contains conclusions regarding whether exposures are occurring, andwhether a health threat is present. In some cases, it is possible to determine whether exposuresoccurred in the past; however, a lack of appropriate historical data makes it difficult to quantifypast exposures. If it is found that a threat to public health exists, recommendations are made to stop or reduce that threat.
Patrick Bayou is a small tidal tributary of the Houston Ship Channel (HSC) that flows through aheavily industrialized area in Deer Park, Harris County, Texas. This 3 mile long, shallow bayouflows past the property boundaries of three petrochemical industries that discharge treated plantwastes and cooling tower wastewater under permit into the bayou. In addition, Patrick Bayoureceives effluent discharges from the City of Deer Park wastewater treatment plant anddischarges from an air separation plant located along the east side of the tributary. On June 14,2001, Patrick Bayou was proposed to the National Priorities List (NPL), because sedimentcontamination in the wetlands bordering the Bayou posed a threat to downstream fisheries.
The Texas Department of Health (TDH) under a cooperative agreement with the Agency forToxic Substances and Disease Registry (ATSDR) reviewed available environmental informationfor the Patrick Bayou site and evaluated the primary pathways through which people mightpossibly come into contact with contaminants from the site. These potential exposure pathwaysinclude groundwater, sediment, surface water, seafood, and air. Based on available information,people are not coming in contact with site contaminants; therefore, the Patrick Bayou NPL site does not pose a public health hazard.
|CATEGORY A. |
URGENT PUBLIC HEALTH HAZARD 1
This category is used for sites whereshort-term exposures (< 1year) tohazardous substances or conditionscould result in adverse healtheffects that require rapidintervention.
|CATEGORY B. |
PUBLIC HEALTH HAZARD 1
This category is used for sitesthat pose a public health hazarddue to the existence of long-termexposures (> 1 year) tohazardous substances orconditions that could result inadverse health effects.
|CATEGORY C. |
INDETERMINATE PUBLIC HEALTH HAZARD
This category is used for sites in which"critical" data are insufficient withregard to extent of exposure and/ortoxicologic properties at estimatedexposure levels.
|CATEGORY D. |
NO APPARENT PUBLIC HEALTH HAZARD 1
This category is used for sites wherehuman exposure to contaminated mediamay be occurring, could have occurredin the past, or could occur in the future,but the exposure is not expected tocause any adverse health effects.
NO PUBLIC HEALTH HAZARD
This category is used forsites that, because of theabsence of exposure, doNOT pose a public healthhazard.
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.
The Patrick Bayou site consists of contaminated sediments within the Bayou - a part of the EastFork Tributary - and associated wetlands. Patrick Bayou is a small tidal tributary of the HoustonShip Channel (HSC) that flows through an urban, heavily industrialized area in Deer Park, HarrisCounty, Texas. The City of Deer Park is divided by a major interstate highway: on the south sideof the highway are small commercial buildings and residential areas; the north side of thehighway consists exclusively of major industrial facilities [Fig. 1]. The mouth of Patrick Bayoubegins on the industrial side of the highway and empties into the HSC. This 3 mile long, shallowbayou is located along the property boundaries of three petrochemical industries that dischargelarge quantities of industrial plant wastes and cooling tower wastewater under permit into thebayou. In addition, Patrick Bayou receives effluent discharges from the City of Deer Parkwastewater treatment plant and discharges from an air separation plant located along the east sideof the tributary. Sediment contamination has resulted from a multitude of discharge sourcessurrounding the site.
Most of the upper part of the Bayou is a series of open, concrete-lined storm water channels andlarge metal/concrete culverts installed to receive storm water runoff and permitted wastewaterdischarges [Figs. 2, 3]. Contaminated sediments have been documented within the bounds ofPatrick Bayou originating below these culverts and extending approximately 3 miles to itsconvergence with the HSC and a portion of the East Fork Tributary. The Bayou is approximately200 feet wide expanding to 600 feet within the last 1/4 mile before entering the ship channel.The lower part of the bayou consists of earthen banks and a soft mud bottom.
In 1993-94, investigations conducted by the city of Houston along the HSC and its tributariesdocumented the presence of pesticides, polycyclic aromatic hydrocarbons (PAHs), cadmium,chromium, mercury, nickel, zinc, and polychlorinated biphenyls (PCBs) accumulating withinPatrick Bayou sediments . Subsequent investigations conducted in 1994 by the Texas NaturalResource Conservation Commission (TNRCC) confirmed the presence of these contaminants inthe sediments .
The water body was targeted for investigation based on the high concentration of discharges, ahistory of fish kills, and data indicating contamination in the sediment. In July 2000, the TNRCCcollected 18 sediment samples as part of a site inspection and found numerous inorganic andorganic contaminants, including mercury and PCBs .
In June of 2001 the site was proposed to the Environmental Protection Agency's (EPA) NationalPriorities List (NPL), because it was determined that sediment contamination in the wetlands bordering the Bayou posed a threat to downstream fisheries. The NPL is a list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under Superfund .
The TDH Seafood Safety Division, as part of its routine monitoring of fish and seafood fromwater bodies in Texas, has sampled fish and crabs at the confluence of the HSC and PatrickBayou . Because of contamination with dioxins, pesticides, and other organic contaminants, aseafood consumption advisory is currently in place for the HSC and its contiguous waters(including Patrick Bayou). Persons are advised to limit consumption of fish and crabs from thisarea to no more than one 8-ounce meal per month. Children, and women who are nursing,pregnant, or who may become pregnant, are advised not to eat any species of fish or crabs fromthe HSC and San Jacinto River.
Large populations of fish and marine animals have been documented near the mouth of PatrickBayou. Local fishermen fish for blue crab and catfish along the HSC even though the taking ofseafood has been restricted by the TDH due to elevated levels of dioxin, PCBs, and pesticides. Fish kills have been reported in the early 1990s in the Patrick Bayou site .
Deer Park receives drinking water from the Trinity River via Lake Livingston . This water ispurchased from the City of Houston through the Coastal River Authority. Once every 2 monthsthe City of Houston assesses the water from this reservoir.
On February 22, 2002, TDH and TNRCC personnel visited the area of Patrick Bayou. Uponentering Deer Park, there was a noticeable odor of industrial emissions. As stated, the north sideof the City is heavily industrialized, while the south side is primarily residential and commercial.The Bayou was not visible from the major highway that divides the industrial from the residentialarea of Deer Park. The entire shoreline of the Patrick Bayou site is lined by three majorindustrial properties; Lubrizol Corp., Shell Oil, and OxyVinyls. For safety reasons, public accessto these properties is restricted 24 hours a day, 7 days a week [Fig. 4]. The companies required asafety video viewing before entering the property and required an escort to tour the bayou. Hardhats and safety glasses were supplied to wear on the site.
The Lubrizol Corp. is located at the upper portion of the Bayou with the shoreline in the back ofthe property. An 8 foot fence divides the Bayou from Lubrizol. A large concrete culvertdischarges wastewater into the Bayou. The Bayou is concrete-lined with steep sides leading toshallow water [Fig. 3].
Shell Oil and OxyVinyls were located further downstream of the bayou. Numerous outfalls wereobserved discharging wastewater directly into the bayou [Fig. 5]. The water was deeper than theupstream portion and the bottom was muddy and clay-like. Numerous bird species were evident,and there was no indication of fishing or crabbing in the area. Public access to the shoreline isrestricted and a pipeline and railroad track cross over the bayou at the confluence of the HoustonShip Channel; this prevents even small boats from entering the bayou [Fig. 6].
The 1990 U.S. Census Bureau data reports 43 housing units and 123 residents within a ½ mileradius of the Patrick Bayou site . Within a 1 mile radius of the site are 798 housing units, witha total population of 2,162 [Fig. 7]. The housing units reported by the Census Bureau are locatedapproximately 2 miles upstream of the facilities discharging waste into the Bayou. The site is inDeer Park, which has a population of approximately 30,000. There is a high school andelementary school, as well as a church day care upstream of the site.
In an effort to collect community health concerns, the Harris County Health District wascontacted. The Harris County Health District reported that, although there is general publichealth concern regarding the numerous industrial facilities in Deer Park, it was not aware ofspecific health concerns regarding the Patrick Bayou site.
During the public comment period, one letter was received from a citizen of Deer Park. Theresponse from TDH has been included in Appendix D as part of the public record. The primaryconcerns of this citizen were the number of cancers in the area and the potential runoff of sitecontaminants into residential areas. The TDH Cancer Registry Division has investigated anumber of cancers from 1995-2001 and has found that although there is a slight increase in lungcancers in the area, they were not able to determine whether these were due to smoking. Regarding runoff of site contaminants, the residential areas of Deer Park are located upstream of the site and would not be affected by runoff of contaminants in flood situations.
The presence of chemical contaminants in the environment does not always result in exposure toor contact with the chemicals. Because chemicals only have the potential to cause adverse healtheffects when people actually come into contact with them, it is exposure, or the contact thatpeople have with the contaminants that drives the public health assessment process.
People can be exposed to chemicals by breathing, eating, drinking, or coming into direct contactwith a substance containing the contaminant. This section reviews available information todetermine whether people in the community have been, currently are, or could in the future beexposed to contaminants associated with this site.
To determine whether people are exposed to site-related contaminants, investigators evaluate theenvironmental and human components leading to human exposure. This analysis consists ofevaluating the five elements of an exposure pathway: a source of contamination, transportthrough an environmental medium, a point of exposure, a route through which the contaminantcan enter the body, and an exposed population. Exposure pathways can be complete, potential,or eliminated. For a person to be exposed to a contaminant, the exposure pathway must becomplete. An exposure pathway is considered complete when all five elements in the pathwayare present and exposure has occurred, is occurring, or will occur in the future. A potentialpathway is missing at least one of the five elements but could be completed in the future. Aneliminated pathway is missing one or more elements and will never be completed. Table 1identifies pathways important to this site. The following discussion incorporates only thosepathways relevant and important to the site.
Because exposure does not always result in adverse health effects, whether the exposure could besufficient to pose a hazard to people in the community is also evaluated. The factors thatinfluence whether exposure to a contaminant or contaminants could or would result in adversehealth effects include: (1) the toxicologic properties of the contaminant, (2) how much of thecontaminant the individual is exposed to, (3) how often, how long, or both that exposure isallowed to occur, (4) the manner in which the contaminant enters or contacts the body (breathing,eating, drinking, or skin/eye contact), and (5) the number of contaminants to which an individualis exposed (combinations of contaminants). Once exposure occurs, characteristics such as age,sex, nutritional status, genetics, life style, and health status of the exposed individual influencehow the individual absorbs, distributes, metabolizes, and excretes the contaminant.
When identifying plausible potential exposure scenarios, the process begins by assessing thepotential public health significance of the exposure. This is done by comparing contaminantconcentrations to health assessment comparison (HAC) values for both non-carcinogenic andcarcinogenic endpoints. HAC values are media-specific contaminant concentrations used toscreen contaminants for further evaluation. While exceeding a HAC value does not necessarilymean that a contaminant represents a public health threat, it does suggest that the contaminantwarrants further consideration.
Non-cancer comparison values are also known as environmental media evaluation guides(EMEGs) or reference dose media evaluation guides (RMEGs) and are respectively based onATSDR's minimal risk levels (MRLs) and EPA's reference doses (RfDs). MRLs and RfDs areestimates of daily human exposure to a contaminant that is unlikely to cause adverse non-cancerhealth effects over a lifetime. Cancer risk comparison values are also known as carcinogenic riskevaluation guides (CREGs) and are based on EPA's chemical specific cancer slope factors and anestimated excess lifetime cancer risk of 1-in-1-million persons exposed for a lifetime. Here,standard assumptions are used to calculate appropriate HAC values .
The environmental data used in this public health assessment were obtained from the 2001TNRCC site screening inspection report . Data were available for sediment only. Thesamples were analyzed for volatile and semi-volatile organic compounds (VOCs and SVOCs),PCBs, pesticides, and metals. All samples were collected according to EPA-approved QualityAssurance Project Plans and the sample locations were approved by the EPA prior to samplecollection. The analysis and conclusions in this report are valid only if the referencedinformation is valid and complete.
To assess the public health significance of this site, potential exposure to site contaminants ingroundwater, sediment, surface water, air, and seafood consumption were considered (Table 3). Because the likelihood that people could come into contact with contaminants in groundwaterand air is low to non-existent, these pathways were eliminated from further analysis. Thepathways important to this site are presented in Table 1.
To assess sediment contamination, the TNRCC collected eight background and 19 sourcesediment samples (all samples collected at 0-20" depth) (Table 2). Six source sediment samplescontained SVOCs (hexachlorobutadiene and hexachlorobenzene) above HAC values and 11source sediment samples contained PCBs (Aroclors 1248 and 1254) above HAC values (Table3). Background sediment samples collected upstream of the site did not contain anycontaminants above HAC values.
Because, public access to the shoreline is restricted by the bordering industrial facilities thepotential for exposure to site contaminants in the sediment is low. Based on availableinformation, TDH has concluded that contaminants in the sediment do not pose a public health hazard.
The upstream portion of Patrick Bayou is bordered by steep concrete embankments that preventthe migration of sediment to the adjacent industrial areas. There is no physical barrier to preventmigration of contaminants in the sediment to the downstream wetland area and the confluence ofthe HSC; however, public access to these areas is restricted by the bordering industrial facilities.
Although surface water data were not available for evaluation, there is little or no potential forhumans to be exposed to any contaminants which might be in the surface water. Therefore, the surface water pathway does not pose a public health hazard.
For safety reasons, the industries located along the shoreline of Patrick Bayou restrict publicaccess, requiring escorts while on site. Also, there are several above ground industrial pipelinescrossing the bayou near the north entrance that effectively restrict access by boat. Therefore,public fishing within Patrick Bayou is not likely to occur.
As stated, the bayou empties into the HSC. In the past, TDH determined that fish and crabs fromthe HSC pose a public health hazard. Because of dioxins, pesticides, and other organiccontaminants, TDH currently has a seafood consumption advisory in place for the HSC and itscontiguous waters (including Patrick Bayou). Consumption of fish and crabs from this areashould be limited to no more than one 8-ounce meal per month. Children, and women who arenursing, pregnant, or who could become pregnant, are advised not to eat any species of fish orcrabs from the Houston Ship Channel and San Jacinto River .
Health outcome data (HOD) record certain health conditions that occur in populations. Thesedata can provide information on the general health of communities living near a hazardous wastesite. They can also provide information on patterns of specified health conditions. Someexamples of health outcome databases are tumor registries, birth defects registries, and vitalstatistics. Information from local hospitals, and other health care providers can also be used toinvestigate patterns of disease in a specific population. TDH and ATSDR look at appropriateand available health outcome data when there is a completed exposure pathway or communityconcern. Due to the lack of completed exposure pathways, a review of health outcome data was not required for this site.
TDH has prepared this PHA under a cooperative agreement with ATSDR. In accordance withATSDR's Child Health Initiative, TDH has included the following information.
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 are adults from certain kinds of exposures tohazardous substances. They are more likely to be exposed because they play outdoors and theyoften bring food into contaminated areas. Children are shorter than adults, which means theybreathe dust, soil, and heavy vapors close to the ground. Generally speaking, children also aresmaller than adults, resulting in higher doses of chemical exposure per body weight. Also, thedeveloping body systems of children can sustain permanent damage if toxic exposures occurduring critical growth stages. Most importantly, however, most children depend completely onadults for risk identification and management decisions, housing decision, and access to medicalcare.
TDH evaluated the potential for children living in the vicinity of Patrick Bayou for exposure tosite contaminants at levels of health concern. Although contaminants in the sediment exceed thehealth based comparisons for children, exposure to site contaminants is not occurring and is not likely to occur in the future.
Based on available information, TDH was not able to identify any pathways through whichpeople would likely come into contact with site contaminants. TDH has concluded that, atpresent, Patrick Bayou does not pose a public health hazard.
There are no public health recommendations for the site at this time.
TNRCC/EPA plan to proceed with the remedial investigation of the site.
- ENSR. Houston Ship Channel Toxicity Study Project Report. Houston, Texas: ENSRConsulting and Engineering and Espey Huston and Associates. 1995.
- Texas Natural Resource Conservation Commission. Contaminant Assessment of PatrickBayou. Houston, Texas: TNRCC Field Operations, Region 12; 1996 December.
- Texas Natural Resource Conservation Commission. Screening Site Inspection Report for Patrick Bayou, TX0000605329, Deer Park, Harris County, Texas. Houston, Texas; 2001 January.
- United States Environmental Protection Agency. National Priorities List (NPL). Patrick Bayou, Deer Park, Texas. Washington, DC; 2001 June.
- Texas Department of Health, Seafood Safety Division. Health Consultation(s) forconsumption of seafood from the Houston Ship Channel; 2001. Available at: URL: www.tdh.state.tx.us/bfds/ssd.
- Bureau of the Census. 1990 census population. Washington, DC: US Department ofCommerce; 1995.
- Agency for Toxic Substances and Disease Registry. Public Health Assessment GuidanceManual. Chelsea, Michigan: Lewis Publishers; 1992.
Lisa R. Williams, M.S.
Environmental Epidemiology and Toxicology Program
John F. Villanacci, Ph.D.
Environmental Epidemiology and Toxicology Program
ATSDR REGIONAL REPRESENTATIVE
George Pettigrew, P.E.
Senior Regional Representative
ATSDR - Region 6
ATSDR TECHNICAL PROJECT OFFICER
Robert B. Knowles. M.S., REHS
Environmental Health Scientist
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
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.
Robert B. Knowles
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this Public Health Assessment and concurs with its findings.
Sven E. Rodenbeck
for Roberta Erlwein
Chief, State Programs Section, SSAB, DHAC, ATSDR
|ATSDR||Agency for Toxic Substances and Disease Registry|
|CERCLA||Comprehensive Environmental Response, Compensation and Liability Act of 1980|
|CREG||Carcinogenic Risk Evaluation Guide|
|EMEG||Environmental Media Evaluation Guide|
|EPA||Environmental Protection Agency|
|HAC||Health Assessment Comparison Value|
|HSC||Houston Ship Channel|
|MRL||Minimal Risk Level|
|NPL||National Priorities List|
|PAHs||Polycyclic Aromatic Hydrocarbons|
|PHA||Public Health Assessment|
|RMEG||Reference Dose Media Evaluation Guide|
|SARA||Superfund Amendments and Reauthorization Act of 1986|
|SVOCs||Semi-Volatile Organic Compounds|
|TDH||Texas Department of Health|
|TNRCC||Texas Natural Resource Conservation Commission|
|VOCs||Volatile Organic Compounds|
|PATHWAY NAME||PRIMARY CONTAMINANTS OF CONCERN||EXPOSURE PATHWAY ELEMENTS||TIME||CONCLUSIONS|
|SOURCE||ENVIRONMENTAL MEDIA||POINT OF EXPOSURE||ROUTE OF EXPOSURE||EXPOSED POPULATION|
|Potential Exposure Pathways|
|Surface water||not sampled||wastewater discharge from local industries / site operations||surface water||swimming, |
|dermal, incidental ingestion||workers |
|No public health hazard; sufficient evidence indicates that residents do not use the site for recreational purposes or drinking water|
|wastewater discharge from local industries / site operations||sediment||on-site, |
|No public health hazard; sufficient evidence indicates that people would not be likely to come in contact with sediment on a frequent basis. Public access to shoreline is restricted|
|not sampled||wastewater discharge from local industries / site operations||fish and crabs||fishing |
|ingestion||nearby residents||past |
|No public health hazard; sufficient evidence indicates that residents do not use the site for recreational purposes. Public access to shoreline is restricted|
|Sample Location||Specific Location (sample depth)|
|SE-01||Houston Ship Channel||Up-channel from Patrick Bayou (composite 0-18")|
|SE-02||Houston Ship Channel||Up-channel from Patrick Bayou (grab 0-20")|
|SE-03||Houston Ship Channel||Up-channel from Patrick Bayou (grab 0-18")|
|SE-10||East Fork||Upstream from Praxair outfall entry to tributary (grab 0-8")|
|SE-11||East Fork||Upstream from Praxair outfall entry to tributary (grab 0-8")|
|SE-12||East Fork||Upstream from Praxair outfall entry to tributary (grab 0-10")|
|SE-15||Patrick Bayou||Upstream from Deer Park wastewater discharge point (composite 0-4")|
|SE-16||Patrick Bayou||duplicate of SE-15|
|SE-04||Houston Ship Channel||confluence of HSC and Patrick Bayou (grab 0-18")|
|SE-05||Houston Ship Channel||confluence of HSC and Patrick Bayou (composite 0-20")|
|SE-06||Houston Ship Channel||duplicate of SE-05|
|SE-07||Houston Ship Channel||down channel sample 300' west of OxyVinyl outfall (grab 0-16")|
|SE-08||Houston Ship Channel||down channel sample 300' west of OxyVinyl outfall (composite 0-18")|
|SE-09||Houston Ship Channel||duplicate of SE-08|
|SE-14||East Fork Tributary||confluence of East Fork with Patrick Bayou (composite 0-14")|
|SE-17||Patrick Bayou||40 meters downstream from Lubrizol/Deer Park Outfall (composite 0-6")|
|SE-18||Patrick Bayou||20 meters downstream from Shell Road Bridge / west bank (composite 0-8")|
|SE-19||Patrick Bayou||800' north of confluence with East Fork (composite 0-18")|
|SE-20||Patrick Bayou||60 meters N. OxyVinyl #001 24 meters from E. shoreline (composite 0-20")|
|SE-21||Patrick Bayou||duplicate of SE-20|
|SE-22||Patrick Bayou||45 meters S. OxyVinyl #003 21 meters from E. shoreline (composite 0-18")|
|SE-23||Wetland sample||700' north of East Fork along edge of east bank (composite 0-20")|
|SE-24||Patrick Bayou||83 meters south of island 17 meters from E. shoreline (composite 0-16")|
|SE-25||Wetland Sample||60' N. of SE-14 along edge of east bank (composite 0-22")|
|SE-26||Patrick Bayou||200' E. of bridge in lower bayou area (grab 0-18")|
|SE-27||Wetland sample||along NE shoreline of island in Patrick Bayou (composite 0-15")|
|SE-28||Wetland sample||duplicate of SE-27|
|Contaminant||Hexachlorobutadiene||Hexachlorobenzene||Aroclor 1248||Aroclor 1254|
|Health Assessment Comparison Value |
|9,000 CREG2||400 CREG||400 CREG||400 CREG |
10,000 EPA chronic EMEG3
10,000 ATSDR chronic RMEG4
1Only those samples with detectable levels of contaminants were listed, all other samples had non-detectable levels of contaminants; shaded areas indicate sample was not detectable at reported limits. Health based comparison values are based on an assumed ingestion rate of 200 milligrams (mg) of soil for children (body weight 10 kilograms (kg) and an ingestion rate of 100 mg of soil for adults (body weight 70 kg).
1ug/kg=micrograms per kilogram
2CREG=cancer risk evaluation guide and is based on an excess cancer risk of one in one-million persons exposed over a lifetime
3EMEG=environmental media evaluation guide and is based on ATSDR's MRL for chronic exposure
4RMEG=reference dose media evaluation guide and is based on EPA's RfD for chronic exposure (unless otherwise specified)
Texas Department of Health
|Eduardo J. Sanchez, M.D., M.P.H. |
Commissioner of Health
|1100 West 49th Street |
Austin, Texas 78756-3199
Gary R. Bego
Charles E. Bell, M.D.
February 6, 2003
I would like to thank you for taking the time to review and comment on the Draft Public HealthAssessment for Patrick Bayou in Deer Park, Texas. Your letter was well thought out andinformative. You brought up a number of excellent points regarding Patrick Bayou. Your letterwill be included in the Appendix of the Public Health Assessment (without personal identifiers)as part of the public record.
We have corrected the demographic section stating that "no schools or day care facilities arelocated within two miles of the site" based on the information you provided. We were able tolocate the specific public facilities you listed to determine that they are indeed located within atwo mile radius of the site.
As part of the public health assessment process, we compare background contaminant levels withcontaminant levels in samples taken from the site. Background levels are naturally occurringsubstances in the environment that have not been influenced by the site, either because they areupstream from the site or outside of the area of contamination.
We then compare contaminant levels to health assessment comparison values. These values areestimates of daily exposure to a contaminant that is unlikely to cause adverse health effects overa lifetime. None of the contaminants levels in background samples exceed health basedcomparison values. The public facilities you listed are further upstream from the site than thebackground samples were. Therefore, it is not likely that site contaminants have migratedbeyond the background sampling area (south of highway 225).
Although several site samples contained organic contaminants exceeding health basedcomparison values, we determined that the potential for contact with contaminants from the sitewas negligible for the public because public access to the site is restricted. I visited the site inearly 2002, and was required to be escorted onto and off the site as public access is restricted 24hours a day, 7 days a week.
It is possible that a large storm such as the one you mentioned in 1979 could cause massive flooding and therefore runoff of contaminants of any of the facilities in Deer Park. However,waterways such as Patrick Bayou tend to flood during high rainfall events because runoff fromhigher elevation areas is coming in faster than it can be carried away and not because water isflowing backwards up the bayou from further downstream. Furthermore, the contaminants foundin Patrick Bayou tend to adhere strongly to soil and are hydrophobic (lack affinity for water). Exposure to any contaminants from the site or from any of the facilities in Deer Park would befurther minimized by a huge dilution factor. Potential health effects from contaminants on thesite would only be expected to occur after repeated exposure to large quantities of the chemical.
The Cancer Registry Division of the Texas Department of Health conducted an investigation intothe occurrence of cancer in the Deer Park area in 1995-1997. A number of specific cancers wereinvestigated. It was found that there was a slight increase in lung cancers in the area; however,they were not able to determine whether this increase was caused by smoking.
Concerning the use of soil from Patrick Bayou for fill material on residential yards and lotsduring the 1980's, past exposures to site contaminants are difficult to address, because we are notable to quantify the level of exposure. It is beyond the scope of the Texas Department of Healthto determine the occurrence and cause of cancer in any community over the past 25 years andproject what can be expected for the next 25 years for the average citizen.
On a personal note, I am sorry for your battle with cancer and wish you a quick recovery. It isextremely difficult to link exposure to environmental chemicals directly to a specific cancerbecause of the massive and sometimes conflicting information linking cancer to a multitude ofcauses.
I hope this information has been useful to you. Please feel free to contact me at (800) 588-1248if you have further questions or concerns. I am also enclosing a brochure for information on the Cancer Registry Division at the Texas Department of Health.
Lisa R. Williams, M.S.
Environmental Epidemiology and Toxicology Division