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PUBLIC HEALTH ASSESSMENT ADDENDUM

CRYSTAL CHEMICAL COMPANY
HOUSTON, HARRIS COUNTY, TEXAS


SUMMARY

The Crystal Chemical Company, a National Priorities List site, islocated on a 5-acre tract off Westpark Drive in Houston, Texas. The company was in operation from 1968 to 1981 and manufacturedarsenic-based herbicides. In 1988, the Agency for ToxicSubstances and Disease Registry (ATSDR) prepared and released aHealth Assessment for this site. ATSDR concluded that soil,surface water, and ground water at the Crystal Chemical site werecontaminated with arsenic both on and off site. They alsoconcluded that children playing in the area and workers involvedin remediation on and off site could be exposed to site arsenicthrough oral, skin, and inhalation exposures.

This Public Health Assessment Addendum evaluates the publichealth implications of new environmental sampling informationfrom the Supplemental Feasibility Study (SFS), reviews theCrystal Chemical Company Exposure Study findings, and comments onthe proposed clean-up levels for arsenic with remediation of thesite. Based on the review of the SFS environmental data, thissite continues to be a public health hazard because nearbyresidents, particularly children, who walk or play along the siteboundaries may be exposed to arsenic in off-site soils, sediment,and surface water through ingestion or direct skin contact. Remediation workers will be at risk of arsenic exposure throughskin contact and inhalation of dust unless the appropriatepersonal protective equipment is used.

In May 1988, ATSDR, the Texas Department of Health, and theHouston Health and Human Services Department conducted anexposure study among nearby residents of the Walnut BendApartments family section. Urine arsenic levels of children andadults who walked or played in the arsenic-contaminated areaswere compared to the urine arsenic levels of those residents whodid not walk or play in these areas. The average concentrationof urine arsenic for both groups was normal, showing thatgenerally most persons were not being exposed to arsenic.However, three children who played around the arsenic-contaminated areas had higher than expected urine arsenic levels. When these children were retested three months later, their urinearsenic levels had returned to normal levels, probably becausethey no longer played in arsenic-contaminated areas on and nearthe site.

The U.S. Environmental Protection Agency (EPA) has developed a 30ppm clean-up level for off-site contaminated soils as part ofremediation of the site. Health effects are not likely to occurat this level of arsenic in soil.


BACKGROUND

A. Site Description/History

This Addendum to the Crystal Chemical Health Assessment (1988)has been written for the following purposes:

  1. to incorporate new environmental sampling informationfrom the Supplemental Feasibility Study (SFS);

  2. to discuss the Crystal Chemical Company Exposure Studyfindings;

  3. to comment on the proposed clean-up levels for arsenicwith remediation of the site.

The Crystal Chemical Company site, which is on EPA's NationalPriorities List of hazardous waste sites, is located on fiveacres of land near Westpark Drive in Houston, Texas. The CrystalChemical Company manufactured arsenic-based herbicides from1968-1981. The major products were mono- and disodiummethanarsenic acid (MSMA and DSMA) and cacodylic acid (CACO). The site is bordered on the west by the Southern Pacific Railroadeasement and tracks and the Harris County Flood Control Channel. Charles F. Guyon, Inc is located north of the property. SouthernPacific Railroad owns the property to the east. Waco FinancialCorporation (previously Tidewater Financial Company) owns theproperty south of the site. Southern Pacific Railroad tracksseparate the site from this property. Walnut Bend Apartments arelocated within one-quarter mile northwest of the site. AppendixA contains a map of the site with the bordering properties andlocations of monitoring wells.

In 1981, Crystal Chemical Company declared bankruptcy andabandoned the site, leaving approximately 99,000 gallons ofarsenic trioxide in a storage tank and approximately 600,000gallons of process wastewater in ponds. In 1981 and 1982emergency clean-up activities, EPA removed the liquid waste fromthe ponds and disposed it in an approved, hazardous wastefacility off the site. EPA also mixed the top foot of soil withlime and deposited it in the wastewater ponds on site.

The site was capped with a polyethylene cover and topped withapproximately 6 to 12 inches of clay. The arsenic trioxide inthe storage tanks was sold. The buildings and equipment weredecontaminated, sold, and relocated off site, leaving the sitevacant except for one small concrete building, a utility pole,and an electrical service panel.

In 1986, EPA determined that the existing Crystal SiteInvestigation/Feasibility Study (SI/FS) should be supplementedwith an additional study that would evaluate the use of treatmenttechnologies. This Supplemental Feasibility Study (SFS) wascompleted by EPA in 1990. The public health implications of theadditional environmental data and proposed clean-up levels arediscussed in this Addendum to the Health Assessment.

In 1988, the Agency for Toxic Substances and Disease Registry(ATSDR) prepared and released a Health Assessment for the CrystalChemical Company Site. Appendix B contains a copy of this HealthAssessment. Based on an October 1987 ATSDR site visit and datareviewed at that time, ATSDR concluded that surface andsubsurface soils and the surface water and ground water at theCrystal Chemical site were contaminated with arsenic both on andoff site. Surface soil and surface water were the media of mostconcern in regard to adverse health effects. The susceptiblereceptor populations were children playing in the area andworkers involved in remediation on and off site through oral,skin, and inhalation exposures. ATSDR recommended at that timethat "health advisories should be considered as a result ofpotential arsenic exposure via the ingestion and dermalabsorption of arsenic from the surface soil and surface water bychildren playing around the site".

The following observations were noted during ATSDR site visits inOctober 1987 and March 1988, areas of severe erosion, areaswithout vegetation, low lying areas where surface water runoffhad collected, and the removal of all but one of the warningsigns originally posted at the site. A gravel berm or mounddesigned to control surface water run-off and the polyethylenecap liner had deteriorated sufficiently around the perimeter ofthe site to allow off-site migration of arsenic.

Supported by ATSDR's health assessment recommendations, EPAinitiated an Immediate Removal Action in September 1988 tocorrect these problems. These actions included the following:

  1. Capping adjacent contaminated off-site areas including those in the southwest corner of the site,part of the Westpark Drive extension along the northsite boundary, and the southeast corner of the site;

  2. Measures to repair and control erosion of the existingon-site soil cap and around the flood control channel;

  3. Repairing and installing fencing to restrict access toareas of high contamination;

  4. Posting 15 warning signs in areas of high visibilityaround the site;

  5. Securing the Southern Pacific Railroad gate with a newlock.

In 1988, ATSDR along with the Texas Department of Health (TDH)and the Houston Health and Human Services Department conducted anexposure study for the Crystal Chemical site. The Exposure Studyis discussed in this Addendum.

In September 1990, EPA Region 6 released the Record of Decision(ROD) for the selected remedial action for the Crystal Chemicalsite. The ROD addresses the contaminated soils on and off siteas well as the contaminated ground water. The selected remedyincludes the following:

  1. Excavating or removing arsenic-contaminated soil above30 ppm from off site and placing this soil on the site.

  2. Treating the on-site soil with arsenic contaminationgreater than 300 ppm.

  3. Installing a multi-layer cap of clay, plastic, sand, topsoil, and vegetation over the entire site after thesoils have been treated.

  4. Pumping ground water from the contaminated aquifers andtreating this water on site until arsenic levels are ator below 0.05 ppm.

  5. Discharging the treated water to public owned treatmentworks, an area surface water body, or reinjecting itinto the ground.

  6. According to EPA, a review will be conducted withinfive years after the beginning of remedial action tomake sure that the remedy continues to provide adequateprotection of public health.

B. Site Visit

Dr. Jean Brender, Dr. Suzanne Hahn, and Mr. David Boston, staffmembers with the TDH Environmental Epidemiology Program,conducted a site visit on November 12, 1990. We did not go onsite during our visit. In addition to characteristics noted inthe original Health Assessment, we made the followingobservations from the perimeter of the site.

A 6-foot high chainlink fence topped with barbed wire surroundedthe site. Signs were posted in the area identifying it as ahazardous waste site. However, we saw several signs lying on theground along the flood control channel. In addition, the northand northwest fenced areas did not have signs posted. Theseareas are of concern because of their proximity to WestparkDrive. A gate to the site was located at the northwest end. This gate was chained and padlocked; however, the gate could beopened enough to allow pedestrian entry to this area.

We also saw evidence of human activities in nearby off-siteareas. Graffiti was seen on many parts of the bridge that islocated near the northwest corner of the site. Bicycle trackswere noted along the banks of the drainage channel. We also sawevidence that the flood control channel area had recently beenmowed.

The flood control channel had areas of severe erosion followingalong drainage pathways from the Crystal Chemical site. Patchyvegetation was present throughout the channel area. At the timeof the visit, approximately 1 to 1.5 feet of water was present inthe flood control channel. Fish (minnows) and a variety ofinsects were observed around the bridge area. At the time of ourvisit, we did not note any on-site activity.

C. Demographics, Land Use, and Natural Resource Use

The Alief area, where the Crystal Chemical sites located, isundergoing rapid transition. Originally a small agriculturalcommunity, land use has changed from industrial to apredominantly mixed residential and office area. Schools,apartments, and offices exist within 1500 feet of the site.

According to the 1980 U.S. Census, approximately 1,199 personslive within the census tract where the Crystal Chemical site islocated. The Census indicates that 111 (9.3%) residents are lessthan 10 years of age. The racial make-up includes 1043 (87.0%)whites, 79 blacks (6.6%), and 77 (6.4%) of other racialbackgrounds. An estimated 162 (13.5%) persons are of Spanishorigin.

The Walnut Bend Apartments family section is locatedapproximately 1,000 feet northwest of the site and is the nearestresidential area to the site. A survey conducted by ATSDR, TDH,and the Houston Health and Human Services Department in 1988indicated approximately 440 residents in this apartment complex. About 30% of the interviewed residents were 2 through 10 years ofage. Sixty-five percent of the participants were white, 30% wereblack, and the rest were from other racial groups.

The area also includes approximately 9 million square feet ofoffices, with 65,000 workers. It is anticipated that this trendof increased residential/commercial use will continue,particularly after remediation and the planned completion of thesection of Westpark Drive adjacent to the site.

D. State and Local Health Data

State vital statistics data (birth and mortality data) areavailable for Texas cities with 2500 or more residents. Thesedata are not available in Texas by zip code or census tract. Because the Crystal Chemical site and surrounding area are partof Houston, the only available birth and mortality dataincorporate statistics for the entire Houston area. These healthstatistics cannot be considered appropriate health indicators forthe population surrounding the Crystal Chemical site.

In May 1988, ATSDR, TDH, and Houston Health and Human Services Department conducted an exposure study for the Crystal Chemical site. A copy of this study can be obtained by contacting TDH or ATSDR. The objectives of the exposure study were to (1) determine whether adults or children walked or played around the on-site or off-site contaminated areas; (2) measure recent human exposure to arsenic through analyses of urine samples; and (3) determine whether activity or time spent at the contaminated site were correlated with arsenic levels in urine. The results of this study will be discussed in the Health Outcome Data Evaluation section.


COMMUNITY HEALTH CONCERNS

On March 29, 1988, Drs. Dennis Perrotta, Jean Brender, andRichard Beauchamp of TDH and representatives from ATSDR (CarlHickam, Nancy Hicks, and Dr. Jeffrey Lybarger) met with RobertFalletti of the Houston Health and Human Services Department(HHHSD) to discuss whether an exposure study should be conductedat the Walnut Bend apartments. At that time, HHHSD staff did notidentify any specific community health concerns.

Residents of the apartment complex expressed several healthconcerns during the exposure survey in May 1988. Citizens alsoexpressed health concerns at the EPA public meeting about theCrystal Chemical site on June 21, 1990. Concerns included thefollowing:

  1. Is the area around the Walnut Bend apartmentscontaminated with arsenic?

  2. Had children with elevated urine arsenic levels(identified in the exposure study) been playing inyards that had been sprayed with arsenic in addition toplaying around the site?

  3. Would the waste treatment facility (to be constructed)and processes emit fugitive dusts, gases, and odorsinto the neighboring properties?

  4. Was arsenic from the Crystal Chemical site seeping intothe drinking water?

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The Crystal Chemical Company Site Health Assessment (released in1988) identified arsenic as the major contaminant both on siteand off site. This health assessment reviewed and evaluated theenvironmental data from the 1984 Site Investigation andFeasibility Studies. The present addendum to this HealthAssessment evaluates additional environmental data released inthe Supplemental Feasibility Study. Under the direction of theU.S. Environmental Protection Agency (EPA) Region 6, AppliedEngineering and Science, Inc. (AES) collected additional samplesof ground water, off-site surface soils (depth unspecified),off-site surface water, and sediments during October 1987. AESalso collected ground-water samples in April 1989.

The tables in this Section list the contaminants of concern fromthe 1987 and 1989 environmental sampling results. We evaluatethese contaminants in the subsequent sections of the HealthAssessment Addendum and determine whether exposure to them haspublic health significance. The levels of contaminants found in1987 and 1989 will also be compared to levels reported in the1988 Health Assessment. We select and discuss these contaminantsbased upon the following factors:

  1. Concentrations of contaminants on and off the site.

  2. Field data quality, laboratory data quality, and sampledesign.

  3. Comparison of on-site and off-site concentrations withbackground concentrations, if available.

  4. Comparisons of on-site and off-site concentrations withATSDR Health Assessment Comparison (HAC) values for (1)noncarcinogenic endpoints and (2) carcinogenic endpoints.

  5. Community health concerns.

In the data tables that follow under On-site Contamination andOff-site Contamination, the listed contaminant does not mean thatit will cause adverse health effects from exposures. Instead,the list indicates which contaminants will be evaluated furtherin the Health Assessment Addendum. When selected as acontaminant of concern in one medium, that contaminant will bereported in all media.

The data tables include the following acronyms:

  • EMEG = Environmental Media Evaluation Guide

  • HAC = Health Assessment Comparison value

  • MCL = Maximum Contaminant Level

  • ppm = parts per million

  • RfD = Reference Dose

ATSDR Health Assessment Comparison (HAC) values are contaminantconcentrations in specific media that are used to selectcontaminants for further evaluation. These values includeEnvironmental Media Evaluation Guides (EMEGs) and other relevantguidelines. Maximum Contaminant Levels (MCLs) representcontaminant concentrations that EPA deems protective of publichealth (considering the availability and economics of watertreatment technology) over a lifetime (70 years) at an exposurerate of two liters per day. EPA's Reference Dose (RfD) is anestimate of the daily exposure to a contaminant that is unlikelyto cause adverse health effects.

We conducted a search of the Toxic Chemical Release Inventory(TRI) for the zip code area of the Crystal Chemical site. TheTRI did not list any facilities having chemical releases in thesite area.

A. On-Site Contamination

AES collected only on-site ground-water samples in 1987 and 1989,but did not collect on-site samples from any other environmentalmedia. The 1988 Health Assessment reported soil arsenicconcentrations at the former pond #1 location from 27,000 ppm ata depth of four feet to 923 ppm at 24 feet. The concentration ofarsenic in the other former pond areas ranged from approximately8500 ppm to 2500 ppm near the surface and extended vertically toseveral hundred ppm at depths of 15 feet.

Ground Water - Monitoring Wells

The Crystal Chemical site contains five monitoring wells screenedat 15 feet, three monitoring wells screened at 35 feet, and onemonitoring well screened at 100 feet. AES collected six ground-water monitoring well samples in 1987 and four ground-watermonitoring well samples in 1989. They obtained three of the 1989samples from MW-14, MW-15, and MW-16 that were installed in 1989. Appendix A contains a map that shows the locations of the on-sitemonitoring wells and Table 1 reports the arsenic concentrationranges by depth that ground water was screened. The highestlevels of arsenic at the 15-foot level were found at MW-15 (161ppm in 1987 and 171 ppm in 1989). At the 35-foot level, MW-2 andMW-3 had the highest levels of arsenic at 292 ppm and 359 ppm,respectively. Phenol was detected in several wells screened at15 feet and 35 feet. The maximum value detected for phenol (0.23ppm) was well below the ATSDR HAC value for this chemical and allEPA Drinking Water Health Advisories. AES also collected ground-water samples in 1987 for analyses of volatile and semi-volatileorganic compounds. None of these compounds were detected atlevels of public health concern.

Compared to levels reported in the 1988 Health Assessment, groundwater at the 35-foot and 100-foot levels have lower levels ofarsenic in 1987 and 1989.

Table 1.

Range of Arsenic Concentrations in On-Site Ground-Water Monitoring Wells*
Ground-water Depth Range of Levels - ppm Date HAC Value ppm HAC Source
15 feet 0.006 - 0.483
0.029 - 161
10-87
04-89
0.01 EMEG
35 feet 0.02 - 359 10-87    
100 feet** 0.007
0.004
10-87
04-89
   

* Supplemental Feasibility Study Investigation, 1990.
** One well screened at this depth.

In 1989, AES sampled an on-site Crystal Chemical water supplywell (WSW-1) and found 0.928 ppm of arsenic. This well isscreened at 300 feet according to the SFS.

B. Off-site Contamination

AES obtained off-site data for soil, monitoring wells, public andprivate wells, surface water, and sediment during theSupplemental Feasibility Study in 1987 and 1989.

Soil

AES collected 21 off-site soil samples on the outer perimetersurrounding the site and adjacent properties to the east of thesite. Appendix C contains a map that shows the locations ofthese soil samples, and Table 2 reports the range of arsenicfound in there samples. Although the SFS indicates that thesamples were from surface soils, no soil depths are given in thedocument. As part of the Immediate Removal Action in 1988, soillevels of arsenic were screened at the site with use of an X-rayFluorescence instrument.

Three off-site soil samples were sent for laboratoryconfirmation. Table 2 indicates the results of this sampling.

In the Immediate Removal Action, the EPA performed off-siteimprovements to reduce the rate of erosion which occurred west ofthe site near the drainage canal. A temporary clay cap wasplaced over off-site surface soils that had been found to containhigh levels of arsenic. The EPA completed these improvementsafter the additional surface soil samples were collected by AES. Therefore, current levels of arsenic in the southwest corner ofthe site, part of the Westpark Drive extension along the northsite boundary, and the southeast corner of the site are likely tobe less than those found in 1987.

Table 2.

Range of Arsenic Concentrations in Off-Site Soils
Range of Levels - ppm Date HAC Value ppm HAC Source
14.2 - 1220
387 - 644
10-87*
11-88**
50
50
EMEG
EMEG

* Supplemental Feasibility Study Investigation, 1990.
** From Ecology and Environment, Inc., as reported in the Immediate Removal Action Report, 1990.

According to the 1984 Site Investigation, winds in the CrystalChemical site area are usually from a south to south-eastdirection. Arsenic levels in soils ranged from 23 ppm to 886 ppmupwind and 41 ppm to 520 ppm downwind from the site. Alloff-site soil samples collected adjacent to the site can beconsidered downhill from the site with the exception of samplesSS-3, SS-4, SS-5, and SS-6. North of and immediately adjacent tothe site, arsenic levels in soils ranged from 281 ppm to 520 ppmarsenic. In the soils between the site and the flood controlchannel concentrations of arsenic ranged from 14 ppm to 1220 ppm. Levels of arsenic south of the site ranged from 52 ppm to 886ppm. Samples collected east of the site ranged from 41 ppm to957 ppm of arsenic. Small amounts of phenols were detected insome soil samples, but not at levels of public health concern.

AES collected 15 background soil samples in January 1989 outsidea one mile radius, but no farther than a two mile radius of thesite. The samples consisted of the upper three to four inches ofsoil. Arsenic was not detected in any of the soil samples; thedetection limit for the analyses ranged from 1.60 ppm to 1.20ppm.

Ground Water - Monitoring Wells

The off-site area contains four monitoring wells screened at 15 feet and ten monitoring wells screened at 35 feet. AES sampled eight off-site monitoring wells in 1987 and six off-site monitoring wells in 1989. Appendix A contains a map that shows the locations of these monitoring wells and Table 3 reports the arsenic concentrations by screening depth. Small amounts of phenols were detected in some ground-water samples, but not at levels of public health concern. Because ground-water flow varies by depth and is in several directions, it is difficult to specify which samples are upgradient and downgradient. At the 15-foot zone, ground-water flow has a slight gradient toward the northeast from the west, southwest, and southeast. At the 35-foot zone, flow is toward the northwest, west, and south from the northwest corner of the site near MW-2 that contained 291 ppm of arsenic. The highest levels of arsenic in off-site ground-water monitoring wells were found at MW-20 (258 ppm) that is approximately 150 feet north of the site and screened at 15 feet and at MW-5 (366 ppm) that is approximately 80 feet north of the site and screened at 35 feet. With the exception of MW-19 and MW-17A, all monitoring wells greater than 200 feet from the site perimeter had arsenic levels below detection limits (<0.005 - <0.01). Compared to previous findings, the levels of arsenic in ground water have not significantly changed. AES also collected ground water samples in 1987 for analyses of volatile and semi-volatile organic compounds. None of these compounds were at levels of public health concern. None of the off-site monitoring wells are screened at the levels of the Lower Chicot Aquifer (source of water in the area) or the Evangeline Aquifer (major source of ground water in the area).

Table 3.

Range of Arsenic Concentrations in Off-Site Ground-Water Monitoring Wells*
Ground-water Depth Range of Levels - ppm Date HAC Value ppm HAC Source
15 feet 0.006 - 258 04-89 0.01 EMEG
35 feet <0.005 - 366
<0.002 - 0.036
10-87
04-89
   

* Supplemental Feasibility Study Investigation, 1990.

Ground Water - Public and Private Wells

AES sampled eight off-site deep wells in July 1989. They alsosampled the water supply well located at Guyon Alloys in October1987 and April 1989. Table 4 reports the arsenic levels in thesewells, and Appendix D contains a map that shows the locations ofthe wells. All sampling results for arsenic were below the EPAMCL of 0.05 ppm. Arsenic levels at the sampled city wells wereat or below 0.01 ppm. The 1988 Health Assessment indicated thatthe Guyon well had an arsenic level of 0.06 ppm. AES did notdetect arsenic in this well in 1987 or 1989.

Table 4.

Range of Arsenic Concentrations in Off-Site Public/Private Water Supplies*
Well Name Location Arsenic ppm Date
Tap on City Supply Line CW-1 0.011 07-89
Andrau Airport #1 AA-1 <0.003 07-89
Andrau Airport #2 AA-2 0.008 07-89
Western Atlas #2 WA-2 0.032 07-89
Western Atlas #3 WA-3 <0.003 07-89
City Well 51-1 0.004 07-89
City Well 51-2 0.005 07-89
HL&P Substation HLP-1 0.004 07-89
Guyon Well   <0.005
<0.002
10-87
04-89
HAC Value - ppm
HAC Source
0.01
EMEG
 

* Supplemental Feasibility Study Investigation, 1990.

Surface Water

AES collected five samples of surface water in October 1987, fourfrom the Harris County Flood Control Channel and one from a ditchlocated on the northeast perimeter of the site. Appendix Econtains a map that shows the locations of these surface waterstations and Table 5 reports the arsenic concentration ranges. In the flood control channel, one sample was collected about 240feet upstream, two adjacent to the site, and one approximately200 feet downstream. The upstream sample showed an arsenic levelof 0.06 ppm and the downstream sample an arsenic level of <0.005. A duplicate sample of the downstream water, however, indicated0.016 ppm of arsenic. The highest level of arsenic (0.506 ppm)was found in the ditch northeast of the site (sample SW-15).

Table 5.

Range of Arsenic Concentrations in Off-Site Surface-Water Samples*
Concentration Range - ppm Date HAC Value ppm HAC Source
<0.005 - 0.506 10-87 0.01 EMEG

* Supplemental Feasibility Study Investigation, 1990.

Sediment

AES collect 16 sediment samples (not specified whether grab orcore samples) in October 1987. Appendix E contains a map thatshows the locations of these sediment sampling stations, andTable 6 reports the arsenic concentration range. Small amountsof phenol were detected in all sediment samples, but not atlevels of public health concern. The Site Investigation releasedin 1984 reported the highest concentrations of arsenic to benorth of the site in the drainage ditch that is adjacent to theGuyon Alloy property. The 1987 sampling results show that theconcentrations of arsenic north of the site are much lower thanpreviously found. The highest concentration of arsenic foundnorth of the site was 482 ppm. South of the site, arsenic levels ranged from 306 ppm to 924 ppm, compared to previous levels of418 ppm to 541 ppm. The area immediately east of the site(Southern Pacific Railroad Company) contained up to 850 ppm ofarsenic (SED-11). Sediment in the flood control channelcontained less than 60 ppm arsenic in samples collected north andnorthwest (upstream) of the site. The sediment sample collectedwest of the site in the flood control channel contained 278 ppmarsenic and the sample south of the site (downstream) contained28 ppm arsenic. AES collected a sample in 1987 from dredgingsduring Harris County Flood Control District routine maintenanceoperations on the western slope of the drainage canal. Thissample contained 35 ppm arsenic. According to the Harris CountyFlood Control District, however, they have no record of anydredging activities for 1985 through May 1991, in the portion ofthe flood control channel adjacent to the site (personalcommunication, May 30 and June 3, 1991).

Table 6.

Range of Arsenic Concentrations in Off-Site Sediment Samples*
Concentration Range - ppm Date HAC Value ppm HAC Source
5.2 - 924 10-87 50 EMEG

* Supplemental Feasibility Study Investigation, 1990

C. Quality Assurance and Quality Control

We reviewed the Final Quality Assurance (QA) Report of the SFSfor information about their field data and laboratory dataquality. The AES Project QA Officer documented all fieldoperations by completion of the field notebook, field trackingforms, and chain of custody forms. The contract laboratoryundertook various laboratory quality control steps that includedfrequent instrument calibrations, analysis of calibration checkstandards, and analysis of spiked duplicate, and reagent blanksamples.

One of the surface-water samples (SW-2) containers broke in transit to the subcontractor laboratory and could not be analyzed for phenols. The results for duplicate samples analyzed in October 1987 showed acceptable analytical precision for arsenic and phenols. The results for duplicate samples analyzed on April 1, 1989, also showed the precision of analysis was acceptable with the exception of one ground-water sample from MW-21. In general, the data generated by the laboratories met all QC standards in recoveries and precision. When recovery rates were not within control limits, the samples were reanalyzed.

D. Physical and Other Hazards

During our site visit, we did not note any physical or otherhazards on site. The adjacent flood control channel represents aphysical hazard since persons could fall into the channel. During the site visit, however, we observed a water depth of onlyabout 1 to 1.5 feet of water in the channel.


PATHWAYS ANALYSES

A. Environmental Pathways

The 1988 Health Assessment for the Crystal Chemical siteidentified the following environmental pathways for transport ofarsenic off site:

  1. Surface soil along the property line was contaminatedwith high levels of arsenic, and some of these areaswere sparsely vegetated.

  2. The surface cap along the edges of the site haddeteriorated sufficiently to allow surface water fromrainfall to carry arsenic off site to the railroadtracks, flood control channel, and other drainageditches.

  3. The sediment in the flood control channel wascontaminated with arsenic by surface water runoff fromthe site. During dredging operations, this sedimenthad been spread along the side of the bank of the floodcontrol channel.

  4. The ground water was heavily contaminated with arsenicin the shallower zones.

  5. Wind erosion re-entrainment of dust could occur becauseof high levels of arsenic in the surface soils andsparse vegetation in heavily contaminated areas.

Based on the 1987 and 1989 environmental sampling results, theseenvironmental pathways have not changed with the exception ofarsenic contaminant levels in the southwest corner of the site,part of the Westpark Drive extension along the north siteboundary, and the southeast corner of the site. EPA placed atemporary clay cap over these off-site surface soils that hadbeen found to contain high levels of arsenic. Therefore, runoffof arsenic contaminated water into the flood control channelshould be reduced as well as levels of arsenic in the surfacesoils and fugitive dusts.

Once remediation starts, this work will temporarily increase thepotential for air borne particulates from on-site subsurfacesoils being disturbed. During remedial activities, surfacerunoff of arsenic might increase from the possible disturbance ofthe clay cap.

B. Human Exposure Pathways

The 1988 Health Assessment for the Crystal Chemical siteidentified the following human exposure pathways:

  1. Direct contact and possible ingestion of contaminatedsoil, dusts, and surface water by workers on site,children playing along the railroad tracks and/or theflood control channel, or maintenance workers cleaningthe flood control channel or clearing the railroadtracks.

  2. The inhalation of contaminated dusts by workers on thesite, children playing in the area, and maintenanceworkers in the area.

  3. The possible drinking of contaminated ground water byemployees of the Guyon General Piping and/or RadnorAlloys.

Based on the 1988 Health Assessment findings and the findings inthis Addendum, Table 7 identifies the completed pathways andTable 8 identifies the potential exposure pathways. Completedpathways require a source of contamination; transport through anenvironmental medium; a point of exposure; a route of humanexposure and an exposed population. Potential pathways, however,require that at least one of these five elements is missing, butcould exist. Both kinds of pathways could have occurred in thepast, could be occurring now, or could occur in the future.

Ingestion and skin contact with contaminated on- and off-sitesoils could have occurred in the past among nearby Walnut BendApartment residents with an estimated 100 children in the familysection of the apartment and among remedial and maintenanceworkers. The EPA Immediate Removal Action in 1988 reduced someof the risk for exposure. They installed more extensive fencingto reduce access to off-site contaminated areas and cappedseveral of these off-site areas to reduce direct contact withcontaminated soils.

Table 7.

Completed Exposure Pathways
  Exposure Pathway Elements  
Pathway Name Source Environmental Media Point of Exposure Route of Exposure Exposed Population Time
Soil Crystal Chemical site Soil On site; off-site perimeter of Crystal Chemical site Ingestion and skin contact Walnut Bend Apartment residents, remedial and maintenance workers Past
Present
Future
Flood control channel and drainage ditches on perimeter of site surface water. Crystal Chemical site Surface water Flood Control channel and ditches on perimeter of site Ingestion and skin contact Walnut Bend Apartment residents Past
Present
Future
Flood control channel and drainage ditches on perimeter of site surface water. Crystal Chemical site Sediment Flood control channel and ditches on perimeter of site Ingestion and skin contact Walnut Bend Apartment residents, maintenance workers Past
Present
Future


Table 8.

Potential Exposure Pathways
  Exposure Pathway Elements  
Pathway Name Source Environmental Media Point of Exposure Route of Exposure Exposed Population Time
Dusts -- on the waste site and the perimeter of the site Crystal Chemical site Soil On site with future remedial activities, off-site perimeter in areas with little vegetation Ingestion
Inhalation
Skin contact
Site remedial workers, Maintenance workers, Residents in nearby apartments Past
Present
Future
Private and industrial wells Crystal Chemical site Ground water (Private and industrial wells) Guyon General Piping Ingestion?
Skin contact?
Employees of Guyon General Piping? Past

Contact with contaminated surface water and sediment also mayhave occurred in the past, may still be occurring, and may occurin the future if off-site migration of arsenic is not preventedthrough the appropriate site remediation. Children who play inthe flood control channel could be exposed to elevated levels ofarsenic in both the surface water and sediment through directskin contact and ingestion.

Once site remediation begins, remedial workers will be atincreased risk for exposure to arsenic-contaminated dusts andsoils when the clay cap on site and nearby off-site contaminatedareas are disturbed. They could come in contact with the soiland dust through inhalation, ingestion, and direct skin contact. Nearby residents could also come in contact with these dusts ifthey walk or play around the site perimeter during remedialactivities.

Shallow ground water has been found to be contaminated witharsenic both on and off site. No nearby public or private wellswere found to have elevated levels of arsenic in 1989. Inearlier sampling, however, the Guyon well had an arsenic level of0.06 ppm which is slightly above the current MCL of 0.05 ppm. Workers in the past at this company may have been exposed to thewell water through ingestion and skin contact. We do not havedocumentation to indicate that these exposures occurred in thepast, however.


PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

Introduction

In this section, we will discuss the health effects in personsexposed to arsenic, discuss the Exposure Study findings, andaddress specific community health concerns. To evaluate healtheffects, ATSDR has developed a Minimal Risk Level (MRL) forcontaminants commonly found at hazardous waste sites. The MRL isan estimate of daily human exposure to a contaminant belowwhich non-cancer, adverse health effects are unlikely to occur. MRLs are developed for each route of exposure, such as ingestionand inhalation, and for the length of exposure, such as acute(less than 14 days), intermediate (15 to 364 days), and chronic(365 days or more). ATSDR presents these MRLs in ToxicologicalProfiles. These chemical-specific profiles provide informationon health effects, environmental transport, human exposure, andregulatory status. In the following discussion, we used theATSDR Toxicological Profile for Arsenic.

Arsenic

Arsenic exposure has occurred and might be still occurring tosome residents at the Walnut Bend Apartments and maintenanceworkers through several completed exposure pathways. Before theEPA Immediate Removal Action in 1988, past exposure to arsenicoccurred in adults and children who walked or played along theperimeter of the site through skin contact and ingestion(primarily children) of contaminated off-site soils, sediment,and surface water. Furthermore, maintenance workers might havebeen exposed to arsenic through skin contact, ingestion, andinhalation of dusts while mowing the grass along the floodcontrol channel.

ATSDR has an MRL of 1 ug/kg/day for inorganic arsenic ingestion. This MRL is based on several human studies. Children are morelikely to ingest soil than adults. Children, who are one to sixyears with an average weight of 16 kg, are estimated to ingest200 mg soil per day. Older children, who are 7 to 15 years withan average weight of 35 kg, are estimated to ingest 100 mg soilper day and adults (70 kg average weight) about 50 mg per day. Based on the highest level of arsenic found in off-site soil in1987, which was 1220 ppm, the estimated exposed dose would exceedthe oral MRL for both younger and older children, but not foradults.

When taken by mouth, a common effect of arsenic is irritation ofthe digestive tract, leading to pain, nausea, vomiting, anddiarrhea. A pattern of skin abnormalities including theappearance of dark and light spots on the skin, and small "corns"on the palms, soles, and trunk can also occur from ingestion ofarsenic. Other effects typical of arsenic exposure by mouthinclude decreased production of red and white blood cells,abnormal heart function, blood vessel damage, liver and/or kidneyinjury, and impaired nerve function causing a "pins and needles"feeling in the hands and feet. (ATSDR Toxicological Profile forArsenic.)

Sensitive individuals in exposed populations often begin to showone or more of the characteristic signs of arsenic poisoning atoral doses of about 20 ug/kg/day. Effects are usually mild atthis exposure level. Although the estimated exposed doses foryounger and older children near the Crystal Chemical siteexceeded the ATSDR MRL for arsenic, all estimated doses werebelow 20 ug/kg/day.

Nearby residents and maintenance workers may have also come incontact with arsenic-contaminated soil, sediment, and surfacewater through skin contact in the past. Arsenic in contact withthe skin may cause an allergic reaction, leading to red, inflamedareas on the skin.

The EPA Immediate Removal Action in 1988 reduced both the accessto and the potential contact with off-site, arsenic contaminatedareas. Therefore, nearby residents should not come in contactwith site-related arsenic if they stay out of the Harris CountyFlood Control Channel and the fenced site area.

During remediation, clean-up workers are likely to receive thegreatest degree of exposure to arsenic-contaminated soil andground water. Skin contact with arsenic-contaminated media,particularly the highly contaminated soil, may lead to red,inflamed skin. Skin contact could result directly from handlingthe contaminated soil and from contaminated airborne dust, thatcould be generated during clean-up activities. Irritated skinalso could occur in nearby residents if they come in contact withhighly contaminated soil, ground water, and dust.

Clean-up workers might also be exposed to arsenic throughinhalation of dusts during remediation. These dusts could causeirritation of the eyes, nose, and throat if the appropriatepersonal protection equipment are not used.

EPA post remediation target goals for arsenic are less than 31ppm in off-site soil and less than 300 ppm in contaminated soilsbeneath a cap that would make these soils inaccessible to thenearby residents. Based on soil ingestion rates discussedearlier, the oral MRL for arsenic would not be exceeded at the 30ppm clean-up level, and health effects are not likely to occur atthis level.

The EPA post-remediation target level of arsenic in ground wateris 0.05 ppm, the current maximum contaminant level for drinkingwater. Elevated levels of arsenic were found primarily in the15-foot and 35-foot zones. Off-site wells in the area are muchdeeper than 35 feet. Arsenic levels in city well drinkingsources were below 0.01 ppm. Therefore, the oral MRL would notbe exceeded by drinking this water. Furthermore, migration ofarsenic to these deeper water sources would be minimized bypumping and treating the contaminated shallow ground water.

According to several studies, persons who are exposed to highlevels of airborne arsenic in or around smelters have anincreased risk for lung cancer. Studies have also found thatchronic oral exposure to elevated levels of arsenic increase therisk for skin cancer. The reported levels of exposure and lengthof exposure in these studies greatly exceed the estimatedexposures at the Crystal Chemical site. Therefore, these typesof health effects are unlikely to occur as the result of livingnear or working at the Crystal Chemical site.

B. Health Outcome Data Evaluation

In May 1988, ATSDR, TDH, and HHSD conducted an exposure study forthe Crystal Chemical site. We contacted all households in afamily apartment complex nearest the site. We conductedhousehold interviews with 355 residents to collect demographicinformation (age, sex, race, length of residence in theapartments) and to determine whether children and adults worked,walked, rode bicycles, or otherwise played in the vicinity of thecontaminated areas in and around the site. The interview waslimited to information about possible routes of exposure toarsenic at the site and other possible exposure opportunities toarsenic such as occupation or diet. We requested urine specimensfrom children and adults from two groups of residents, one basedon a random sample of apartment residents (who did not report anyactivities around the site) and the other based on responses thatplaced residents at risk of arsenic exposure from the site(reported activities around the site).

We measured the amount of arsenic in the urine of 5 children and17 adults who walked and played in the arsenic-contaminatedareas. We compared these urine arsenic levels with measurementsfrom 12 children and 15 adults who did not walk and play in thearsenic-contaminated areas. Since adults and particularlychildren ingest a small amount of soil each day, we know that thearsenic in soil will show up in their urine. The averageconcentrations of urine arsenic for both groups were normal,showing that generally most persons were not being exposed toarsenic. However, three of five children under age ten hadhigher than expected urine arsenic levels.

These children had played in arsenic-contaminated areas within aweek of collecting the urine samples. Several months later, weretested urine arsenic levels in these children and found thatthey had returned to normal levels. As part of the interview, wecautioned the residents to stay away from the contaminated areasof the site area. The urine arsenic levels of the three childrenmay have returned to normal because they no longer played inthese areas. We shared the results of this health study in alocal public meeting for interested citizens.

We also provided copies of the final report to nearby localpublic libraries for citizen review.

C. Community Health Concerns Evaluations

We have addressed each of the community concerns about health asfollows:

  1. Is the area around the Walnut Bend apartmentscontaminated with arsenic?
  2. In addressing this question, we will consider the soil,surface water, sediments, and drinking water at theapartments. In 1983, D'Appolonia Waste ManagementServices, Inc. took three soil samples (upper two tothree inches) immediately south of the apartments. Arsenic levels in these soils ranged from 2 to 20 ppm. These arsenic levels are not of public health concern.

    The section of the flood control channel that isadjacent to the apartments is upstream from the CrystalChemical site. Therefore, arsenic would not migrateoff-site into the surface water and sediment of thissection of the channel.

    The Walnut Bend apartments are on the city public watersupply. Arsenic levels at the sampled city wells in1989 were at or below 0.01 ppm. City water is obtainedfrom deeper aquifers than the ground water foundcontaminated underneath the site and adjacent areas.

  3. Had children with elevated urine arsenic levels(identified in the exposure study) been playing inyards that had been sprayed with arsenic in addition toplaying around the site?
  4. In the survey, children and adults were asked questionsabout other opportunities for arsenic exposure. Noneof the children with elevated urine arsenic levels werereported to have these exposures.

  5. Would the waste treatment facility (to be constructed)and processes emit fugitive dusts, gases, and odorsinto the neighboring properties?
  6. According to EPA, the in-situ vitrification processincludes devices that would control fugitive emissions. Dust control measures will also be implemented duringremediation. According to EPA, air sampling will beconducted to detect any potential problems.

  7. Was arsenic from the Crystal Chemical site seeping intothe drinking water?
  8. As discussed under the first community health concern,arsenic levels at the sampled city wells in 1989 wereat or below 0.01 ppm. The current MCL for drinkingwater is 0.05 ppm. The SFS indicated that ground-watercontamination in 1987 and 1989 was limited to the15-foot and 35-foot water bearing zones. The aquifersthat provide drinking water for this area areconsiderably deeper than these shallow zones. However,if the site is not remediated, arsenic will continue tomigrate into the ground water and might eventually,after a long period of time, contaminate drinking watersupplies.


CONCLUSIONS

The new environmental data and the results of the exposure studydo not change the conclusions of the 1988 Health Assessment thatthis site is a public health hazard. Off-site soil, surfacewater, and sediment contamination with arsenic from the sitecould cause adverse health effects to nearby residents andworkers through ingestion of and skin contact with thesecontaminated media. Nearby children are at highest risk ofexposure to arsenic from ingesting contaminated soil, sediment,and surface water. Oral ingestion of arsenic can causeirritation of the digestive tract and skin abnormalities.Although the Exposure Study indicated that most persons were notbeing exposed to arsenic in the nearby apartments, three childrenwho lived in the apartments and played around the CrystalChemical site had higher than expected urine arsenic levels.

Children and remedial workers are at the highest risk forexposure to arsenic through skin contact with contaminated soils,sediment, and surface water. Skin contact with arsenic can causered, inflamed skin.

Although shallow ground water at and adjacent to the site iscontaminated with arsenic, nearby private and public deeper wellsare not contaminated. However, exposure could occur to thecontaminated ground water in the future if wells were placed inthese contaminated areas and used as a source of drinking water.

The risk for exposure to arsenic from the Crystal Chemical sitehas been reduced by the 1988 EPA Immediate Removal Action. Moreextensive and secured fencing was erected around the site and acap was placed over several adjacent off-site contaminated areas. These actions reduced both access to and the potentialfor direct contact with the contaminated soils.

The chosen remediation of the site includes clean up of off-sitesoils to 30 ppm arsenic. This level is protective of publichealth and should not result in any adverse health effects tonearby residents. The treatment of on-site contamination andcapping of the site should prevent further migration of arsenicto off-site soils, sediment, and surface waters as well as toground water.


RECOMMENDATIONS

  1. Maintain current precautionary measures such as warningsigns and fences around the site. Replace and repair signsand fences as necessary to restrict public access to thesite.

  2. Collect water samples at least annually from industrial,commercial, private, and public wells that are locatedwithin 1 mile of the site until ground water remedial actionhas been completed or until there appears to be no threat tothe aquifers supplying these wells.

  3. Protect persons on and off the site during remediation fromexposure to any dusts or vapors that might be released.

  4. Implement institutional controls to prevent future use ofcontaminated ground water for drinking water untilremediation has reduced contaminant concentrations to belowlevels of health concern.

  5. Conduct monitoring of ambient air and adjacent surfacewaters and sediments in the flood control channel duringremediation to determine if nearby workers and residents areexposed to arsenic.

  6. Provide on-site remedial workers with adequate protectiveequipment and training, in accordance with 29 CFR 1910.120,and follow appropriate National Institute for OccupationalSafety and Health and Occupational Safety and HealthAdministration guidelines.

HEALTH ACTIVITIES RECOMMENDATION PANEL (HARP) RECOMMENDATIONS

In accordance with the Comprehensive Environmental Response,Compensation, and Liability Act (CERCLA) of 1980, asamended, the Crystal Chemical Company site has beenevaluated for appropriate follow-up with respect to healthactivities. As a result of the known exposure to sitecontaminants, an Arsenic Exposure Study was conducted onaffected residents. The final report was made available inJuly, 1989. No other health follow-up activities areplanned at this time. ATSDR and TDH will continue to reviewthe environmental data as it becomes available, particularlyduring the site remediation, and will reevaluate the sitefor any indicated follow-up.


PUBLIC HEALTH ACTION

To respond to community concerns and based on the HARPrecommendations, the following actions have been or will beperformed to meet the needs expressed by the Recommendations ofthis Health Assessment Addendum.

  1. ATSDR and TDH will continue to coordinate efforts withfederal and state environmental agencies in evaluating thesite's impact on public health and as new data becomesavailable they will provide recommendations to addresspublic health issues.

PREPARERS OF THE REPORT

Texas Department of Health

Reviewers:

Jean D. Brender, R.N., Ph.D.
Director
Environmental Epidemiology Program

Suzanne D. Hahn, D.V.M
Staff Epidemiologist
Environmental Epidemiology Program
Texas Department of Health

Typists and Graphics:

Nancy Ingram
Administrative Technician
Environmental Epidemiology Program

Leticia Cano
Secretary
Environmental Epidemiology Program


ATSDR REGIONAL REPRESENTATIVES

Carl Hickam, R.S.
Senior Regional Representative
ATSDR, Region 6

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


ATSDR TECHNICAL PROJECT OFFICER

William Greim, M.S., M.P.H.
Remedial Programs Branch
Division of Health Assessment and Consultation


CERTIFICATION

This Public Health Assessment Addendum was prepared by the TexasDepartment of Health under a cooperative agreement with theAgency for Toxic Substances and Disease Registry (ATSDR). It isin accordance with approved methodology and procedures existingat the time the Public Health Assessment Addendum was initiated.

William J. Greim
Technical Project Officer, SPS, RPB, DHAC


The Division of Health Assessment and Consultation, ATSDR, hasreviewed this Public Health Assessment Addendum and concurs withits findings.

Director, DHAC, ATSDR


REFERENCES

  1. ATSDR (Agency for Toxic Substance and Disease Registry). 1989. Toxicological Profile for Arsenic. U.S. Department of Health and Human Services, Public Health Service, Agencyfor Toxic Substances and Disease Registry, Atlanta, Georgia.

  2. ATSDR (Kaye, Wendy E., Brender, Jean D., and Suarez,Lucina). 1989. The Crystal Chemical Company ArsenicExposure Study, Houston, Texas. U.S. Department of Healthand Human Services, Public Health Services, Agency for ToxicSubstances and Disease Registry, Atlanta, Georgia.

  3. ATSDR (Howie, Max M. and Harris, Cynthia M.). 1988. HealthAssessment for Crystal Chemical Company Site. U.S.Department of Health and Human Services, Agency for ToxicSubstances and Disease Registry, Atlanta, Georgia.

  4. USEPA (United States Environmental Protection Agency). 1984. Final Report -- Site Investigation, Crystal ChemicalCompany, Houston, Texas. Volume I. Prepared in cooperationwith the Texas Department of Water Resources and the U.S.Environmental Protection Agency by D'Appolonia WasteManagement Services, Inc.

  5. USEPA. 1984. Final Report -- Site Investigation, Crystal Chemical Company, Houston, Texas. Volume II. Prepared incooperation with the Texas Department of Water Resources andthe U.S. Environmental Protection Agency by D'AppoloniaWaste Management Services, Inc.

  6. USEPA. 1990. OSC Report -- Emergency Removal Action, Crystal Chemical Company, Harris County, Houston, Texas.Prepared by Gary W. Guerra, On-scene Coordinator, EPA Region 6.

  7. USEPA. 1990. Record of Decision -- Crystal Chemical CompanySite. U.S. Environmental Protection Agency, Region 6.

  8. USEPA. 1990. Final Report -- Supplemental Feasibility Study. Volume I. Crystal Chemical Company Site. Prepared byMetcalf & Eddy, Inc., for U.S. Environmental ProtectionAgency, Region 6.

  9. USEPA. 1990. Final Report -- Supplemental Feasibility Study. Volume II. Crystal Chemical Company Site. Preparedby Metcalf & Eddy, Inc., for U.S. Environmental ProtectionAgency, Region 6.

APPENDICES

Crystal Chemical Company Site Map and Monitoring Wells
Appendix A. Crystal Chemical Company Site Map and Monitoring Wells.


APPENDIX B: HEALTH ASSESSMENT FOR CRYSTAL CHEMICAL COMPANY SITE, FEBRUARY 18, 1988


PUBLIC HEALTH ASSESSMENT

CRYSTAL CHEMICAL COMPANY SITE
HOUSTON, TEXAS

February 18, 1988


TABLE OF CONTENTS

I. SUMMARY

II. BACKGROUND

III. ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

IV. DEMOGRAPHICS

V. EVALUATION

VI. PUBLIC HEALTH IMPLICATIONS

VII. CONCLUSIONS AND RECOMMENDATIONS

VIII. PREPARERS OF THE REPORT

IX. REFERENCES

X. APPENDIX



SUMMARY

Based on the data submitted, surface and subsurface soils and the surface water and groundwater at the Crystal Chemical Company NPL site are contaminated with arsenic. The contamination is both on-site and off-site. Using the 1980 census figures, the population within a one-mile radius of the site is estimated to be 20,000. Known exposure pathways include direct dermal contact, ingestion of contaminated groundwater, surface water and/or surface soils and the inhalation of fugitive dusts. The media of most concern regarding acute and chronic adverse health effects are the surface soil and surface waters. The susceptible receptor populations are children playing in the area, maintenance workers around the site and contractors involved in remediation activities. The recommendations include: (1) issue a health advisory for the site; (2) inform area residents of the potential health threat of the site; (3) restrict access to the contaminated off-site areas; (4) post more warning signs around the site; (5) monitor surface soil post dredging of the flood control channel for additional contamination; (6) perform additional testing of flood channel waters and drainage ditches for contamination; and (7) periodic real-time air monitoring at the worksite periphery because of a possible increase in airborne arsenic during remediation activities.


BACKGROUND

A. Site Description

Crystal Chemical Company is a 5-acre site located on Westpark Drive in Houston, Texas. The company manufactured several different types of herbicides from 1968 to 1981. The major products were the arsenic based herbicides Mono- and Disodium methanearsenic acid (MSMA and DSMA) and Cacodylic acid (CACO). The area surrounding the site is zoned industrial or commercial. The land on which the site is located is owned by the Southern Pacific Transportation Company and was leased to Crystal Chemical Company.

The site is bordered to the west by Southern Pacific Railroad Easement and then by Houston Flood Control Channel #D124-00-0. The southern border has a railroad easement which separates the site from Security Lumber Company. The property to the east is owned by Southern Pacific and to the north (across Westpark Drive) is Guyon General Piping Inc., and Radnor Alloys. Guyon Alloys has been purchased by Radnor Alloys and shares the same location with Guyon General Piping. Within one-quarter mile to the northwest is the Walnut Bend Apartment Complex.

The main contaminants on-site and off-site are arsenic compounds with lesser amount of phenols. During the late 1970's there were several violations of the Texas Department of Water Resources standards primarily resulting from flooding of the site which the flood waters carrying the contaminants off-site. In addition, spray drift from the spray evaporators located in the process wastewater ponds #1 and #2 contributed to off-site contamination. In September 1981, the day before the U.S. Environmental Protection Agency (EPA) started its immediate removal action at the site, Crystal Chemical Company declared bankruptcy. The site was abandoned, leaving approximately 99,000 gallons of arsenic trioxide (a raw material) in a storage tank and approximately 600,000 gallons of process wastewater in the ponds. During EPA emergency cleanup, the liquid was removed from the ponds and disposed of in a commercial waste disposal facility. The top one-foot of soil was removed, mixed with lime and deposited in the wastewater ponds. A polyethylene cover was placed over the area and that was covered by approximately 6 to 12 inches of clay. The arsenic trioxide was sold, the buildings and equipment were decontaminated and sold, leaving the site vacant except for one small concrete block building, a utility pole, and an electrical service panel. A Remedial Investigation and Feasibility Study (RI/FS) were conducted between May and November 1983 and the report released in January 1984.

B. Site Visit

A site visit was conducted October 21-22, 1987. During the same time, a Southern Pacific Transportation Company contractor, AES was on-site collecting groundwater samples from the monitoring wells, and soil and sediment samples from areas adjacent to the site. In addition, the flood control channel was being dredged and the sediment was spread on the west bank of the channel. Samples were to be taken from the newly exposed sediment from the dredging operation and from the water in the flood control channel. The contractors actually performing the sampling were in level C personal protective equipment. Sampling was to end on October 23 and the results used to prepare a Supplemental Feasibility Study. This new study is expected in 4th quarter 1988.

A walk around the site revealed areas of severe erosion, areas devoid of vegetation, and low lying areas where surface water runoff collected. The site was surrounded by a six-foot high chain link fence topped with three strands of barb wire. There was only one sign posted on-site identifying the site as a hazardous area. However, there were other signs identifying the flood control channel as a hazardous area.

The easily accessible flood control channel bank adjacent to the site was devoid of vegetation and had severe erosion in several places. Earlier sampling results showed this area of the channel bank surficial soil and channel sediment to be contaminated with levels of arsenic exceeding 1000 mg/kg.

At the southwest corner of the site where the railroad tracks split and the spur onto Crystal Chemical property was located, was an area of approximately 750 square feet where surface water runoff collected and remained until it evaporated. This area was easily accessible by walking along the railroad tracks. Earlier sampling results indicated high levels of arsenic contamination (>1000 ppm) in this area. As a result, this area was to be sampled by the contractors. There were other areas within 100 feet that were devoid of vegetation and had experienced severe erosion into other drainage ditches.

The property east of the site was generally overgrown with weeds and scrub-type trees. However, there were areas adjacent to the property line which were bare. The largest such area was near the southeast side of the site, adjacent to the former location of pond #4.

North of the property was Westpark Drive, Radnor Alloys, and Guyon General Piping. There has been commercial development in the vicinity of the site which has led to the widening of Westpark Drive to the west of the site, along with the construction of a new bridge. The road directly in front of the site has not been widened and does not appear to be in use. Earlier sampling of the industrial water supply well at Guyon General Piping showed arsenic levels which exceeded the EPA-drinking water maximum contaminant level (MCL) of 0.05 mg/1 (5). The contractor was to take samples at this well also.

The area inside the fence was not entered because of the level C personal protective equipment requirement. Observations were made from the property line. The cap showed some deterioration near the northwest corner and the black polyethylene liner was clearly visible. This area had slight erosion with the surface water running to the north. The site was clear of structures except a small concrete block building, a utility pole, and a wood panel with several electrical circuit boxes attached.


III. ENVIRONMENTAL CONTAMINATION AND PHYSICAL HAZARDS

The major contamination both on-site and off-site is from arsenical compounds. These compounds consist of MSMA, DSMA, CACO, and trimethyl arsine oxide (TMAO) and may be collectively referred to in this health assessment as arsenic. There were minimal concentrations of phenolic compounds; however, the levels reported do not present a potential health problem.

A. On-site Contamination

Arsenic concentrations in the subsurface soils at the former pond #1 location were the highest on-site. The concentration ranged from 27, 000 mg/kg at a depth of 4 feet to 923 mg/kg at 24 feet. The concentration of arsenic in the other former pond areas ranged from approximately 8500 mg/kg to 2500 mg/kg near the surface and extended vertically to several hundred mg/kg at depths to 15 feet.

The 35-foot sands is a geological formation approximately 35 feet beneath the surface, composed of a silty sand layer 5 to 15 feet thick sandwiched between sandy clay layers. The lower clay layer extends down another 65 feet. Groundwater from the 35-foot sands is contaminated with arsenic up to 600 mg/1. The groundwater is also contaminated in the 100-foot sands at levels of 0.08 mg/1. The 100-foot sands, a silty sand layer, is beneath the 65-foot thick sandy clay layer and has an undetermined thickness.

Areas of highest contamination are located at the former ponds and at the storage areas for raw materials and final products.

B. Off-site Contamination

Arsenic contamination has been found in surficial soil in the immediate areas surrounding the site as well as in the sediment downstream in the flood control channel. Samples taken along the property line show arsenic levels ranging from 200 mg/kg to 8,000 mg/kg. The higher levels can be attributed to the higher on-site concentrations and previous plant operations. Concentrations along the railroad right-of-way adjacent to the arsenic trioxide storage area were the highest with levels between 5,000 and 8,000 mg/kg. There were high levels of arsenic in the flood control channel sediments adjacent to the site with concentrations 1,000 feet downstream exceeding 100 mg/kg. Soil and air monitoring samples taken at the apartment complex and the former Montessori School (currently a day- care center, approximately 1,200 feet south) did not exceed background concentrations.

Groundwater contamination has been found in three off-site industrial wells. Two wells at Houston Shell and Concrete are contaminated with arsenic at levels 0.10 mg/1 and 0.17 mg/1. Houston Shell and Concrete is no longer operating this facility and the wells are out of service. The other well is at Guyon General Piping, which uses the water for industrial washwater. The level in this well is 0.06 mg/1, which exceeds the National Primary Drinking Water Standards.

C. Food Chains

The area around the site is not used for agricultural enterprises and the flood control channel is not large enough to support appreciable quantities of edible aquatic life. However, samples were taken of crawfish and guppies and the results indicated some low arsenic levels. Whole organism analysis of the crawfish indicated concentrations of arsenic up to 3.3 mg/kg. Whole organism analysis of the fish samples also indicated arsenic concentration ranging from 0.75 mg/kg to 0.85 mg/kg. These levels are reported to be within the normal levels for animal tissues (1).

Numerous doves were observed during the site visit. Doves are migratory birds having short residence times in any given area. The hunting regulations strictly govern the length of the hunting season and the number of birds taken per day. If these birds were taken for food, they would not pose a health threat because arsenic intake levels from foraging on and around the site would be limited, arsenic does not biomagnify, the birds do not remain in an area for great lengths of time, and the hunting season is short. In any event, the site is located within the city limits and consequently, in a "no hunting" area.

No edible plants were noticed no-site or around the site. Plant uptake of arsenic depends upon several factors including plant species and the availability of the arsenic for uptake. Depending on plant species, arsenic which is available in the 3 to 30 ppm concentration range may be toxic to the plant. The arsenic level in living plants approaching phytotoxicity levels is usually less than 5 mg/kg on a dry weight basis. Even if there were some edible plants present and living, the levels of arsenic ingested would be of little concern.

D. Physical Hazards

The previously mentioned structures were the only ones present on-site and do not appear to present a hazard.


IV. DEMOGRAPHICS

The site is located in a rapidly growing part of Houston. Within a one-mile radius there are shopping centers, restaurants, apartments, single family housing, commercial offices, and light industrial businesses. There are approximately 8,000 apartment units and 2,500 condominiums in the area, and 9 million square feet of commercial space employing some 65,000 workers (6). In the immediate vicinity there are several vacant lots, as well as some light industrial businesses and the family section of an apartment complex. One apartment complex, Walnut Bend Apartments, has their family section located adjacent to the flood control channel and approximately 1,000 feet northwest of the site. It houses an estimated 100 children ranging from infant to high school age. The complex does not have a designated playground area for the children.


V. EVALUATION

A. Site Characterization

The data package received primarily contained information 4 years old. The latest data received was submitted in July 1986 and consisted of sample results from 4 monitoring wells and a blank sample. Monitoring well #5, just off-site to the north of the entrance to the site, was the only well sampled which showed the presence of contamination. Two samples were taken from well #5 and the concentrations were reported as 412 mg/1 and 434 mg/1. The other monitoring wells, (7, 8 and 13) and the blank were reported as none detected (i.e. <0.01 mg/1).

The number and type (soil, surface water, sediment, etc.) of samples taken during the initial investigation were adequate for characterizing the site at that time. However, more current data would help to determine the extent of migration of the contaminants off-site and any increase in groundwater contamination.

A Data Review Summary was received for the latest sample results (1986), indicating the data for those 6 samples had met the EPA acceptability criteria. There was little quality control data provided in the initial RI/FS. Neither the Case Narrative, prepared by the contractor, nor the Data Review Summary, prepared by the EPA reviewer, were included in the data package. The quality control tables presented in the remedial investigation were incomplete. The tables for phenol were more complete than the tables for arsenic; however, it is the arsenic concentrations that are of the highest public health concern. There was neither indication of the acceptability of the recovery data of the arsenic spikes nor the acceptability of the spiking concentrations. It was difficult to determine if the data quality objectives were met; therefore, it was assumed that the data was of sufficient quality. The conclusions presented in this health assessment are based on the information received. The accuracy of these conclusions accordingly depends on the availability and reliability of the data.

The remedial action alternatives were evaluated with respect to which alternatives would provide protection of public health. A brief summary of the alternatives is in the Appendix. To best protect public health, the removal of contamination from the site is required; however, other remedial alternatives may be acceptable. The level of arsenic remaining should be such that there is no further potential for increase in groundwater contamination and that the current groundwater level be reduced. There is concern for those currently using contaminated groundwater; therefore, consideration should be given to reducing groundwater contaminant levels to below the EPA MCL's, or alternatively, those industries presently using contaminated groundwater should be provided with alternative water supplies. Soil and sediment contamination levels should be reduced to levels that do not increase groundwater and/or surface water concentrations, or in themselves pose a health threat.

B. Environmental Pathways

One of the possible pathways leading to environmental contamination is through surficial soil, which has extremely high levels of arsenic along the property line. The surficial soil is of particular concern since it will not support vegetation in the higher contaminated areas. This allows for easier mobility of the contaminants by other environmental vehicles.

The surface cap along the edges of the site has deteriorated sufficiently to allow surface water from rain events to carry contaminants off-site. The deteriorated cap also allows for water to penetrate the surface and carry contaminants down the underlying aquifers. The runoff also carries contaminants further off-site, to the railroad tracks, flood control channel, and other drainage ditches. Surface water can easily move the contamination (dissolved or adsorbed to soil) further from site because the flow is unhindered by vegetation.

The sediment in the flood control channel was contaminated by surface water runoff from the site. This water brings highly contaminated surficial soil into the channel through the erosion process and also dissolved arsenic through direct contact with the soil. The sediment contributes to contamination downstream by being carried in the current, or allowing some dissolution into the water. During dredging operations, this sediment is spread along the side of the bank it is directly exposed and accessible.

The groundwater is heavily contaminated with arsenic in the shallower zones. This is evidenced by the concentration in monitoring well #5 exceeding 400 mg/1 at a depth of 35 feet. Other industrial wells in the area also have shown past contamination exceeding the EPA MCL for arsenic. These wells are screened at 200- to 250-foot depths.

Wind erosion re-entrainment of dusts is of concern since there are high levels of arsenic in the surficial soils. The re-entrainment can occur through various mechanisms e.g., by dust particles being picked up naturally by the wind, or air currents, vibrations, and mechanical movement created by trains or other machinery operating in the area. One of the more important mechanisms will be through site cleanup, where the equipment performing the excavation may introduce large quantities of particulates into the air.

C. Human Exposure Pathways

The human exposure pathways consistent with the environmental pathways include:

  1. Direct contact and possible ingestion of contaminated soil, dusts, and surface water by workers on-site, children playing along the railroad tracks and/or the flood control channel, or maintenance workers cleaning and dredging the flood control channel or clearing the railroad tracks, etc.

  2. The inhalation of contaminated dusts by workers on-site, children playing in the area, and maintenance workers in the area.

  3. The possible drinking of contaminated groundwater by employees of Guyon General Piping and/or Radnor Alloys.

VI. PUBLIC HEALTH IMPLICATIONS

The public health implications resulting from human exposure to arsenical compounds from the Crystal Chemical site (on-site and off-site) will be discussed via exposure to specific environmental media. Phenolic compounds were also prevalent but were at concentrations which would not pose a risk to public health.

A. Soil

1. Surface Soil

Arsenic generally occurs in soil predominantly in an organic, insoluble adsorbed state, and consists primarily of a mixture of the trivalent and pentavalent chemical states (7). The relative toxicity of arsenite is generally greater than that of arsenate (8). Arsenate exists predominantly in aerobic soils and arsenite is primarily observed under an anaerobic state, a state which is not uncommon under temporarily flooded conditions. This chemical parameter is particularly applicable to this site, where soil along the banks of the Flood Control Channel is a primary health concern.

No regulatory standards have been determined for arsenic in soil to date. Background concentrations in soil average 5-6 mg/kg (9) and may reach as high as 40 mg/kg. Ingestion of soil by children (9 months to 5 years of age) is estimated to be approximately 100 mg/day (10) and, consequently, based on this estimate, direct exposure to arsenic via ingestion is estimated at 0.20-200 ug/day.

Of the 49 sampled locations, background concentrations of arsenic (20 mg/kg) were determined at areas further from the site. This level does not itself represent a public health threat. The area presenting a potential public health concern is located immediately adjacent to the site fence line radiating up to 50 feet in all directions. For instance, north, west and south of the site, levels as high and greater than 1000 mg/kg have been determined. Arsenic levels of approximately 200-600 mg/kg have been determined in the easterly direction. These levels represent 5-25 times the maximal background levels. Upon visitation of the site, ATSDR found evidence of mechanical dredging of the Flood Control Channel adjacent to the site, which may significantly increase arsenic exposure via surface soil along the banks.

Susceptible receptor populations of most concern are: (1) children playing in the area (an apartment complex northwest of the site houses approximately 100 children, and no playground or play area is readily available, (2) workers involved in remediation, and (3) trespassers. The primary human exposure pathways presenting a possible health risk are exposure via: (1) ingestion (2) dermal contact, and (3) inhalation. These human exposure routes may result in both acute and chronic adverse health effects.

Acute arsenic poisoning may result in nausea, vomiting, diarrhea, anemia, and cardiac dysfunction in high risk populations. Trivalent arsenic is rapidly absorbed across the stomach into the intestines and into the bloodstream, and subsequently can readily lead to systemic injury. Renal damage may result in hematuria, glycosuria and necrosis (11, 12).

Another clinical manifestation, resulting from chronic oral exposure to arsenic, is liver disease and liver cancer. The induction of portal hypertension and cirrhosis of the liver may result from chronic arsenic exposure (13, 14). Neurological dysfunction is also common after acute and chronic arsenic exposure and may lead to hearing loss and mental retardation in children (15). Systemic effects, as a result of oral exposure, can be observed in humans at levels of 30-300 ug/kg/day (Lowest Observed Adverse Effect Level (LOAEL)). Short-term exposure to maximal surface soil levels along the Flood Channel of this site of greater than 1000 mg/kg may lead to possible systemic effects in small children playing and, subsequently, ingesting soil in the area. Potential skin lesions may also arise (30-200 ug/kg/day) (LOAEL) with chronic oral exposure at the same concentrations. These skin abnormalities may include hyperpigmentation and hyperkeratosis on the palms and soles of the skin and epidemiological studies reveal a dose dependent relationship between arsenic concentrations and skin cancers (15). Another condition, which is observed with endemic arsenism in Taiwan and positively correlated with hyperpigmentation and keratosis, is Blackfoot disease. Blackfoot disease is a peripheral vascular condition which may eventually progress to ulceration and gangrene of the extremities (15, 16). Arsenic may act as a contact allergen leading to local inflammation. Dermal exposure to arsenic at this site would be of particular concern to maintenance workers involved in dredging of the channel. Children playing in the area may also be exposed dermally to newly exposed soil arsenic contaminants. No precise dose estimates are currently available; however, dermal contact may lead to mild to severe dermatitis of the skin. Additional sampling of this medium is presently in progress.

2. Soil Borings

Inorganic arsenic in the form of arsenate is the predominant arsenical species in the soil borings with maximal concentrations on-site as high as 27,300 mg/kg. Off-site contamination was generally low, except at 35-50 sand zones and at shallow depths east and west of the site in areas that receive storm water run-off from the site. The soil borings do not represent a significant health threat to the receptor populations off-site. However, remedial workers would be advised to wear derma1 protective gear and respirators to avoid possible skin dermatitis and mucous membrane irritations of the eye, nose, and throat resulting from remedial activities in handling soil boring particles on site. NIOSH precautions recommends permissible exposure limits in the workplace at a time weighted average (TWA) of 10 ug/m3 (17).

3. Sediment

The sediment may act as a reservoir for arsenic migrating from the surface waters. Fifty-two samples were initially taken of the sediment from the drainage ditches adjacent to the site. Arsenic concentrations up to 1340 mg/kg were determined and would contribute substantially to the surface soil arsenic concentration. Oral and dermal exposure to arsenic along the banks would be a health concern to children and maintenance workers and remedial workers.

B. Water

1. Surface Water

Exposure to arsenic via surface water, adjacent to the site, is another vehicle of concern to human health. Inorganic arsenic is very mobile in water and levels as high as 200 mg/l have been reported in surface water runoff and approximately 1000 mg/l in standing water. Surface water runoff from the site with contamination as high as 100-200 mg/l was collected adjacent to the southwest corner, where the soil arsenic concentrations were 5,000-8,000 mg/kg. The maximum contaminant level (MCL) for arsenic in the drinking water is 50 ug/l. Children playing and splashing in the runoff would facilitate dermal exposure and possible incidental ingestion of levels high enough to present a significant health risk.

2. Groundwater

Arsenic in the groundwater was predominantly organic in form and existed at high levels on the site (500-600 mg/l). This value is substantially higher than the 50 ug/l standard for drinking water. Remedial workers are currently gathering water samples on site and were equipped for Class C exposure. A site visit revealed no evidence of the residential use of domestic private wells immediately off-site. However, nearby industrial use of wells (Guyon General Piping) may indicate possible oral exposure and dermal exposure via safety showers and a washing of the hands. The levels in these wells (60 ug/l) exceed the drinking water standard of 50 ug/l. Groundwater, in general, does not appear to be a primary public health concern to nearby residential areas.

C. Air

The systemic effects, which may result from inhalation, are similar to those resulting from the chronic oral exposure pathway. For instance, EPA and OSHA permissible exposure limit (PEL) regulatory standard for arsenic in air is 10 ug/m3. Mild irritation to the skin, nose, and throat may occur at 100 ug/m3 and hyperkeratosis at approximately 300 ug/m3. Of much greater concern, is the potential for inhalation of arsenic to increase the risk of lung cancer. Non-occupational exposure to arsenic is thought to increase the risk of lung cancer in areas several kilometers away from arsenic emitting smelters (18). ACGIH recommends a TLV-TWA of 0.2 mg/m3 based on human health effects. Most inhaled arsenic is inorganic and is rapidly absorbed across the lungs and into the bloodstream. Initial air monitoring found inorganic arsenic levels at the site substantially below regulatory standards 0.005-0.04 ug/m3. From this study, air does not seem to be a present health concern in regard to arsenic exposure. However, 27,000 mg/kg arsenic concentrations in soil have been determined in the areas of the former shallow ponds. Possible inhalation of inorganic arsenic via particulates in the air would be the medium of concern to public health during future excavation of these contaminated areas. As a result of the reportedly high concentrations of inorganic arsenic detected in soil, fugitive dusts generated from remedial activities may exceed OSHA standards on-site and outside the site periphery. Thus, airborne arsenic should be monitored for potential exceedance of the OSHA (PEL) standard (10 ug/m3).

D. Food Chain

Exposure to arsenic via the food chain at this site does not appear to be a potential health risk.


VI. CONCLUSIONS AND RECOMMENDATIONS

A. Conclusions

The remedial action alternatives were evaluated with respect to which alternatives would provide the best protection of public health. Alternatives B and E-1, (see Appendix), offer the most protection since both alternatives provide for the removal of the contamination from the site. Some of the remaining alternatives (A, D, E-2, or F) may also adequately respond to public health concerns.

In conclusion, we find that the media of most concern, in regard to adverse health effects, are the surface soil and surface waters. The susceptible receptor populations are children playing in the area and workers involved in remediation on-site and off-site via oral, dermal, and inhalation exposure.

B. Recommendations

  1. Health advisories should be considered as a result of potential arsenic exposure via the ingestion and dermal absorption of arsenic from the surface soil and surface water by children playing around the site. Precautionary measures should be taken by remedial workers as well.

  2. Inform area residents of the potential health threat of the site.

  3. Restrict access to the contaminated off-site areas, especially around the railroad tracks.

  4. Post more warning signs around the site.

  5. Monitor surface soil post-dredging of the channel for additional contamination.

  6. Perform additional testing of flood channel waters and drainage ditches for positive contamination of surface waters.

  7. To best protect public health, the elimination of source contaminants is required. The level of arsenic remaining should be such that there is no further potential for increase in groundwater contamination and that the current groundwater level be reduced to below EPA drinking water MCL, or alternatively, provide alternative water supplies to the industries using contaminated groundwater. Soil and sediment contamination levels should be reduced to levels that do not increase groundwater and/or surface water concentrations, or in themselves pose a health threat.

  8. With remediation, periodic real-time air monitoring should be conducted at the worksite periphery because of a possible increase in airborne arsenic above the OSHA PEL value (10 ug/m3) resulting from a possible increase in fugitive dusts. NIOSH recommendations should be heeded by remedial workers and optimal dust control implemented.

VIII. PREPARERS OF THE REPORT

Environmental Reviewer:

Max M. Howie, Jr.
Environmental Health Specialist
Health Sciences Branch

Health Effects Reviewer:

Cynthia M. Harris, Ph.D.
Toxicologist
Health Sciences Branch


IX. REFERENCES

  1. Final Report--Site Investigation, Crystal Chemical Company, Houston, Texas, Texas Department of Water Resources and the U.S. Environmental Protection Agency, Vol. 1, (Jan. 1984).

  2. Final Report--Site Investigation, Crystal Chemical Company, Houston, Texas, Texas Department of Water Resources and the U.S. Environmental Protection Agency, Vol. 2, (Jan. 1984).

  3. Final Report--Feasibility Study, Crystal Chemical Company, Houston, Texas, Texas Department of Water Resources and the U.S. Environmental Protection Agency, (June 1984).

  4. Final Addendum Report--Feasibility Study, Crystal Chemical Company, Houston, Texas, Texas Department of Water Resources and the U.S. Environmental Protection Agency, (Dec. 1984).

  5. U.S. EPA National Interim Primary Drinking Water Regulations (Dec. 24, 1975).

  6. U.S. Bureau of Census, Houston-Galveston Area Council and Westchase Business Council.

  7. U.S. EPA, Office of Water Regulations and Standards. An exposure and risk assessment for arsenic. Washington D.C.: U.S. EPA. Publication EPA 440/4-85-005.

  8. Klaassen, Curtis D., Amdur, Mary 0., and J. Doull. Toxicology--Basic Science of Poisons, 3rd ed. (1986) 974p.

  9. Walsh, L. M., Keeney, D. R. In: Arsenic Pesticides, ACS Sump. Series 7, Am. Chem. Soc., Washington, D.C. p. 35.

  10. Kimbrough, R. D., Falk, H., and P. Stehr, J. of Toxicol. and Environ. Health 14: 47-93 (1984).

  11. Hamamoto, E. Jap. Med. J. 1649: 2-12 (1955).

  12. Gerhardt, R., Hudson, J., Rao, R., and R. Sobel Arch. Intern. Med. 138: 1267-1269 (1978).

  13. Datta, D. V. Lancet l: 433 (1976).

  14. Morris, J. S., Schmid, M., Newman, S., Scheuer, P. J., Sherlock, S. Gastroenterology 64: 86-94 (1974).

  15. Tseng, W. P., Chu, H. M., How, S. W., Fong, J. M., Lin, C. S., and S. Yeh. J. Natl. Cancer Inst. 40: 453-463 (1968).

  16. Chen, C. J., Chuang, Y. C., Lin, T. M., Wu, H. Y. Cancer Research 45: 5895-5899 (1985).

  17. NIOSH. DHHS (PHS) Pocket Guide to Chemical Hazards (1985).

  18. Pershagan, G. Environ. Health Perspect. 40: 93-100 (1981).

  19. Occupational Safety and Health Administration (OSHA PEL) 29 CFR 1910.1018 43FR 19584 (5/5/78).

X. APPENDIX

Remediation Alternatives

Alternative A: Construct an on-site landfill vault: excavate all hazardous wastes; place 78,000 cubic yards of waste inside the vault and use an additional 21,000 cubic yards as backfill (if not contaminated); dispose of 63,000 cubic yards of soil from initial excavation at a commercial disposal facility; install a groundwater withdrawal system on- and off-site.

Alternative B: Excavate all hazardous wastes both on-site and off-site, approximately 135,000 cubic yards; dispose of all wastes at a commercial disposal facility; a groundwater withdrawal system on- and off-site; dispose of pumped groundwater at a commercial disposal facility; backfill, grade and revegetate excavated areas.

Alternative C: No action; monitor groundwater; inspect and repair cap.

Alternative D: Excavate Pond #1 to a depth of 20 feet, Pond #2 to 15 feet, and Pond #3 to 10 feet; dispose of excavated wastes from on-site and off-site at a commercial disposal facility; install surface cap; install a slurry trench barrier around the site and the contaminated groundwater off-site; install a pressure relief system within the contained area to prevent the rise of groundwater levels.

Alternative E-1: Excavate all on-site and off-site hazardous wastes (135,000 cubic yards); dispose of at a commercial disposal facility; backfill, grade and revegetate excavated areas; install a slurry wall barrier around the groundwater contamination on-site and off-site; install a pressure relief system to prevent the rise of groundwater within the contained area.

Alternative E-2: Construct an on-site landfill vault; excavate all hazardous wastes; place 78,000 cubic yards in vault and use 21,000 cubic yards for backfill (if not contaminated); on-site and off-site slurry wall barrier around groundwater contamination; dispose of 63,000 cubic yards from initial excavation at a commercial disposal facility; install a pressure relief system to prevent the rise of groundwater within the contained areas (if necessary).

Alternative F: Excavate Pond #l to a depth of 20 feet, Pond #2 to 15 feet and Pond #3 to 10 feet; excavate the remainder of the site to a depth of 7 feet; dispose of excavated wastes at a commercial disposal facility (about 56,000 cubic yards from on-site and about 24,000 cubic yards from off-site); construct a surface cap; install a slurry wall barrier around the site and off-site groundwater contamination; install a pressure relief system to prevent the rise of groundwater into the contained area.

Alternative G: Construct a surface cap; construct a slurry wall barrier around the site and around the area of shallow off-site groundwater contamination; install a pressure relief system to prevent the rise of groundwater within the contained area.

Table of Contents



Soil Sampling Locations at the Crystal Chemical site
Appendix C. Soil Sampling Locations at the Crystal Chemical site.


Public and Private Well Sampling Locations Near the Crystal Chemical site
Appendix D. Public and Private Well Sampling Locations Near the Crystal Chemical site.


Surface Water and Sediment Sampling Locations at the Crystal Chemical site
Appendix E. Surface Water and Sediment Sampling Locations at the Crystal Chemical site.


COMMENTS ON ADDENDUM TO HEALTH ASSESSMENT

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 6
1445 ROSS AVENUE SUITE 1200
DALLAS TEXAS 75202-2733
AUG 09 1991

MEMORANDUM
SUBJECT: Comments on Addendum to Health Assessment
  Crystal Chemical Company
  Houston, Texas TXD990707010

FROM: Allyn M. Davis, Director
  Hazardous Waste Management Division (6H)

TO: Carl R. Hickam
  Agency for Toxic Substances and Disease Registry

Thank you for the opportunity to review the draft Addendum to the Health Assessment for Crystal Chemical.

Due to a notification from the only vendor of the ISV technology that they are suspending commercial applications of the technology for an undetermined period of time, EPA is exploring remedial options for the Crystal Chemical site. The ground water extraction and treatment remedy and the portion of the remedy which calls for the excavation of off-site soils to concentrations of 30 ppm of arsenic will remain the same regardless of the source or on-site soils remedy option chosen. EPA will keep you apprised of the situation.

Upon my staff's review of the document, the following comments have been compiled:

Pg. 2, para. 2 - property referred to as Tidewater Financial Company property is currently controlled by Waco Financial Corporation.

Pg. 3, para. 2 - the Supplemental Feasibility Study (SFS) was completed by EPA in 1990; Southern Pacific submitted a draft SFS to EPA in July 1989, however, EPA completed the SFS.

Pg. 21, para 7 - the remediation goal for off-site soils is 30 ppm; i.e., to excavate arsenic contaminated soils with arsenic concentrations above 30 ppm - not 30 ppm and above.

Pg. 26, Recommendation 2. - the collection of water samples from industrial, commercial, private and public wells located within one mile of the site will continue until ground water remedial action has been completed or until there appears to be not threat to the aquifers supplying these wells.

If you have any questions about the comments or the remedy issue, please contact Lisa Marie Price of my staff at x6735.



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