Skip directly to search Skip directly to A to Z list Skip directly to site content

PUBLIC HEALTH ASSESSMENT ADDENDUM

SIKES DISPOSAL PITS
CROSBY, HARRIS COUNTY, TEXAS


PATHWAYS ANALYSES

To determine whether nearby residents are exposed to contaminants migrating from the site, weevaluate the environmental and human components that lead to human exposure. This pathwayanalysis consists of five elements: a source of contamination, transport through an environmentalmedium, a point of exposure, a route of human exposure, and an exposed population. For a personto be exposed to a chemical, the exposure pathway must be completed. An exposure pathway isconsidered completed when all five elements in the pathway are present.

Exposure pathways can be completed, potential, or eliminated. A completed pathway has all fiveelements present and has occurred, is occurring, or will occur in the future. A potential pathway ismissing at least one of the five elements and may or may not be completed in the future. Eliminatedpathways are missing one or more elements and will never be completed. Tables 9a and 9b identifythe completed and potential pathways. Table 10 shows the contaminants and the media in whichthey are found. The following discussion incorporates only those pathways which are relevant andimportant to the site.

A. COMPLETED EXPOSURE PATHWAYS

Waste Material, Soil and Ambient Air

Site workers and former employees, who typically worked closely with contaminated media, mighthave been exposed to site contaminants through inhalation of contaminated air, ingestion ofcontaminated soil and waste, or skin contact with soil and waste. According to ATSDR Records ofCommunication (ROC) at least two workers experienced rashes as a result of exposure to organicvapors being released from the ground during monitor well drilling. It was noted in the ROC thatthe normal ambient air volatile organic compound levels in the working area were one to two ppmabove background levels and that during one sampling event, levels were as high as 10 ppm. Properprecautions were subsequently recommended and implemented (August 16, 1985 letter and January7, 1986 memorandum to the USEPA) (Reference 11). Future exposures to site workers could beeliminated by wearing appropriate personal protective equipment and complying with applicablehealth and safety guidelines.

During our site visit, residents from the surrounding communities indicated that, in the past, childrenplayed on the site. These play activities included climbing on waste barrels as well as bicycle andmotorcycle riding throughout the site. It is likely that these children received exposures throughingestion of and dermal contact with small amounts of waste, soil, dust, and by inhalation of ambientair.

Surface Water

A railroad worker repairing a section of bridge northwest of the MWP had to spend a limited butunspecified amount of time wading in the water without protective gear. He complained aboutstrong odors around his work area. He also complained of frequent coughing and nausea and wasconcerned that adequate health and safety measures were not being met (Reference 12).

Two teen-age boys apparently drank from unspecified on-site lakes supposedly because of the lackof fresh drinking water (Reference 13). They may have each received some ingestion exposure from contaminated surface waters.

TABLE 9a.

SIKES DISPOSAL PITS
COMPLETED EXPOSURE PATHWAYS
PATHWAY NAME EXPOSURE PATHWAY ELEMENTS TIME ESTIMATED NUMBER EXPOSED
SOURCE ENVIRONMENTAL MEDIA POINT OF EXPOSURE ROUTE OF EXPOSURE EXPOSED POPULATION
SOIL WASTE PITS SOIL ON SITE INGESTION
DERMAL CONTACT
WORKERS
CHILDREN PLAYING
PAST 2 OR MORE
AIR WASTE PITS AMBIENT AIR ON SITE INHALATION WORKERS
CHILDREN PLAYING
PAST ?
LAKE WASTE PITS LAKE WATER ON SITE INGESTION ADOLESCENTS PAST 2
SURFACE WATER WASTE PITS SURFACE WATER BENEATH RAILROAD OVERPASS DERMAL CONTACT RAILROAD WORKER PAST

1


TABLE 9b.

SIKES DISPOSAL PITS
POTENTIAL EXPOSURE PATHWAYS
PATHWAY NAME EXPOSURE PATHWAY ELEMENTS TIME ESTIMATED NUMBER EXPOSED
SOURCE ENVIRONMENTAL MEDIA POINT OF EXPOSURE ROUTE OF EXPOSURE EXPOSED POPULATION
AIR WASTE PITS AMBIENT AIR OFF SITE INHALATION LOCAL AREA RESIDENTS PAST
FUTURE
7,600
AIR INCINERATOR AMBIENT AIR ON SITE
OFF SITE
INHALATION REMEDIATION WORKERS
LOCAL AREA RESIDENTS
FUTURE ?
AIR SOIL EXCAVATION AMBIENT AIR ON SITE
OFF SITE
INHALATION REMEDIATION WORKERS
LOCAL AREA RESIDENTS
FUTURE ?
FISH UNKNOWN FISH SAN JACINTO
JACKSON BAYOU
INGESTION PERSONS WHO EAT FISH FROM THESE BODIES OF WATER PAST
PRESENT
FUTURE
?
RESIDENTIAL WELLS UNKNOWN GROUNDWATER RIVERDALE INGESTION
DERMAL CONTACT
RIVERDALE RESIDENTS PAST 100
WATER WASTE PITS SURFACE-WATER RUNOFF OFF SITE INGESTION
DERMAL CONTACT
LOCAL AREA RESIDENTS PAST
FUTURE
?


Table 10.

Contaminants above HAC Values and Media in Which They Are Found
  Waste Soil Sediment Surface Water Ground Water Res. Wells Fish Ambient Air Present Ambient Air Past
Volatile Organic Chemicals                  
Benzene   X   X X     X X
1,1-dichloroethane                 ?
1,2-dichloroethane   X   X X       ?
T-1,2-dichlorethane         X        
1,2-dichloropropene       X         ?
T-1,3-dichlorpropane         X       ?
Toluene         X       ?
Vinyl Chloride       X X       ?
                   
Base/Neutral Compounds X     X          
Bis(2-ethylhexyl)phthalate                  
Bis(2-chloroethyl)ether                  
                   
PCB's   X X X     X    
                   
PAHs                  
Pyrene X                
                   
Metals                  
Arsenic         X        
Beryllium X X X   X ?      
Cadmium         X        
Lead X X X   X X      
Thallium     X   X ?      

NOTE: The question marks (?) signify the lack of past data, but these chemicals were likely to have been present in the past in completed or potential pathways.
NOTE: The Source of contamination for Residential Wells and for Fish is unknown.

B. POTENTIAL EXPOSURE PATHWAYS

Ambient Air

During our site visit, local residents told us that when the site was active, there were strong odorscontinually present in the air. Although no ambient air data exists for the period during which thesite was active, it is possible that on-site workers and off-site residents were exposed via inhalation. Because of the lack of data, we are including this as a potential past exposure pathway but areunable to assess the potential past inhalation exposures that workers and off-site residents may havereceived.

Although there may have been past inhalation exposure, the more recent data of IT-Davy (Reference13) suggest that, as of 1990, there were no longer any significant emissions into the air from the sitethat would pose any on- or off-site health effects.

Future inhalation exposure to residents and improperly protected workers is possible if, during theremediation process, unexpected releases of contaminants occur from the excavation and/orincineration processes. The design of the remediation activities incorporates safeguards against suchunlikely events. These include the previously mentioned perimeter fence-line air monitoring systemand a real-time stack emission monitoring system on the incinerator. Upon detection of fugitiveemissions, these devices will alert workers to take immediate action to reduce emissions.

Surface Water

Past flooding of the Sikes Disposal Pits site has resulted in surface-water runoff reaching the off-siteresidents. As of May 1989, LAN has shown that contaminants from this runoff were not at levels ofconcern. Excavation during the course of remediation could increase the possibility ofcontamination from surface-water runoff. However, the remediation plan includes safeguards thatwould prevent contaminated runoff waters from leaving the site. A system of containment bermsand dikes. Water trapped in these bermed and diked areas will be pumped into lined holding pondsfor subsequent treatment and release into the San Jacinto River.

Residential Wells

Approximately 30 private wells, in the Riverdale Subdivision, draw groundwater from the upperaquifer. Although there was extensive organic chemical contamination in the groundwater beneaththe site, no organic compounds were found in samples from these residential wells. Lead was alsodetected during 1987 and 1989 sampling events in residential wells at concentrations above thecurrent HAC value. Available evidence suggests that there is a clear separation between the leadfound on site and the lead found in the Riverdale Subdivision. Thus it is likely that the source of thelead in the Riverdale well water is not associated with the Sikes site.

About 100 persons who live in the Riverdale Subdivision may have been exposed to lead throughingestion of water from private wells. The contaminated groundwater beneath the site appears tohave been confined with the site boundaries. It is therefore unlikely that any of the surroundingcommunities have been exposed to site contaminants through groundwater.

Subsequent sampling in 1993 revealed lead in residential well water at levels below theEnvironmental Protection Agency's Primary Drinking Water Regulation action level of 15 g/L(Table 7). Therefore, residential wells have been eliminated as a present and future potentialexposure pathway.

Fish

During our site visit, we were told by residents that fishing in the nearby waterways was a commonoccurrence. Additionally, we observed an individual fishing in Riverdale Lake which is located inan area that was previously heavily contaminated with PCBs. Fish at several locations were foundto contain PCBs above HAC values; however, since the levels of PCBs in sediment and soil on-siteare relatively low the source of the PCBs found in the fish is unknown. Persons who ate fish caughtfrom local area waterways may have been exposed to PCBs through ingestion. We were unable to estimate an exposed population for this pathway.


PUBLIC HEALTH IMPLICATIONS

Introduction

In this section, we will discuss the possible health effects that may result from exposure to specificcontaminants, evaluate state and local health data bases, and address specific community healthconcerns.

A. TOXICOLOGICAL EVALUATION

To evaluate non-carcinogenic health effects, ATSDR has developed Minimal Risk Levels (MRLs)for contaminants commonly found at hazardous waste sites. The MRL is an estimate of dailyhuman exposure to a contaminant below which non-cancer, adverse health effects are not expectedto occur. In the event that an MRL is not available, other health effects screening levels and EPA'sRfD may be used. MRLs are developed for each exposure, such as ingestion and inhalation, and fordifferent lengths of exposure, such as acute (less than or equal to 14 days), intermediate (15 to 364days), and chronic (365 days or more). ATSDR presents these MRLs in Toxicological Profiles. These chemical-specific profiles provide information on health effects, environmental transport,human exposure, and regulatory status. These ATSDR Toxicological Profiles are used in thefollowing discussion. Other references are listed at the end of this report in the bibliography. Toevaluate carcinogenic health effects, the USEPA has developed chemical-specific cancer slopefactors (CSF) for contaminants commonly found at hazardous waste sites. These CSFs are used toestimate the increased chance that a person exposed to site contaminants will develop cancer overthe course of a lifetime.

Standard exposure scenarios for both children and adults were calculated, for each of the chemicalsbelow, using the highest concentrations found in the media of concern. We assumed that childrenweigh 16 kilograms, drink 1 liter of water per day, and eat 200 mg of soil per day. Adults wereassumed to weigh 70 kilograms, drink 2 liters of water a day, and eat 50 to 100 mg of soil per day. For worker inhalation exposure, we assumed that they inhaled 23 cubic meters of air per day.Exposure scenarios were developed for each of the exposed populations. A typical worker scenarioassumed an exposure of 5 days per week for 40 weeks per year for 5 years. A typical childtrespasser scenario assumed an exposure of 3 days per week for 25 weeks per year for 2 to 10 years. A typical adolescent scenario assumed an exposure of 7 days per week for 52 weeks per year for 5years. The risk of developing cancer was calculated for adults only.

The following contaminants were chosen for evaluation of potential toxicological effects, becausethey were found at concentrations which exceed HAC values and were in completed exposurepathways. These chemicals are listed below.

Volatile Organic Compounds
   Benzene
   1,2-dichloroethane
   1,2-dichloropropane
   Vinyl Chloride

Base/Neutral Compounds
   Bis(2-ethylhexyl)phthalate

Polychlorinated biphenyls (PCBs)

Metals
   Beryllium
   Lead

Benzene

Exposure to benzene may have occurred in the past through skin contact with vapors, soil, andsurface water; ingestion of contaminated soil and surface water; and through the inhalation ofcontaminated air. Potential future exposure to benzene could occur to workers and off-site residentsthrough inhalation if appropriate safety measures employed during remediation should fail.

Exposure to benzene has been associated with adverse health effects (Reference 14). The degree towhich this exposure will cause adverse health effects in humans depends upon the type of exposure(the route), the amount of the exposure (the dose) and the length of time of the exposure (theduration). The most common routes of exposure are ingestion, dermal contact, and inhalation.

Ingesting high levels of benzene can cause vomiting, dizziness, convulsions, and death. The healtheffects that may result from ingesting low levels of benzene are not known.

Currently, there are no oral MRLs or RfDs available for benzene. However, ATSDR'sToxicological profile for benzene identifies an ingested dose of 1 mg/kg/day as the intermediate (15-364 day exposure) NOAEL (No Observable Adverse Effects Level) for adverse hematological(blood) and immunological (immune system) effects in animals. We estimate that the combinedexposure to benzene from ingestion of soil and surface water is below the intermediate NOAEL. Thus the likelihood of adverse non-carcinogenic health effects from oral exposures to benzene isunlikely.

Death from brief inhalation (5 to 10 minutes) of very high levels of benzene (10,000 - 20,000 ppm,levels much higher than those observed on site) may occur in humans. Inhalation of lower levels(700 - 3,000 ppm, also levels much higher than those observed on site) can cause drowsiness,dizziness, headaches, and unconsciousness. In most cases, the effects from low level exposures arereversible.

ATSDR has determined an acute inhalation MRL for benzene of 0.002 ppm. However, sincehistorical benzene levels were not measured, we were unable to assess the past exposure to workers.

Epidemiological studies on humans show that exposure to benzene through inhalation has adverseeffects on human bone marrow. Long-term exposures to benzene may affect overall bloodproduction, cause anemia, and cause internal bleeding. It has been associated with pancytopenia (areduction in the number of all three major types of blood cells: red blood cells, platelets, and whiteblood cells); aplastic anemia (the cessation of bone marrow function); and a form of preleukemiamyoplastic dysplasia (the filling of the bone marrow with necrotic and fatty tissue). Exposure tobenzene can also suppress the immune system, which could increase the chance for infection andperhaps lower the body's defenses against tumors.

Inhalation exposure to benzene has also been linked to genetic changes in humans and animals. Inanimal studies, benzene has been found to have adverse effects on unborn animals including lowbirth weight, delayed bone formation, and bone marrow damage. Some of these effects have beennoted to take place at levels of 32,000 g/m3 benzene in air (a level much higher than any reportedat the Sikes site). Benzene has been shown to have harmful effects on animal reproduction, but noevidence can be found linking benzene exposure to miscarriages in humans.

There is overwhelming human evidence and supporting animal studies showing that benzene is ahuman carcinogen. Workers exposed to benzene for periods of five to 30 years have developedleukemia. This is a cancer of the bone marrow which impairs the marrow's ability to form whiteblood cells. The type of leukemia most often associated with exposure to benzene is acute myeloidleukemia (AML). With AML, there is a diminished production of erythrocytes, granulocytes, andplatelets, which leads to death by anemia, infection, or hemorrhage.

Due to lack of historical ambient air data, we were unable to estimate the cancer risk from on-siteexposure to benzene. Due to the lack of historical off-site ambient air data, we were unable toestimate the likelihood of adverse health effects to workers or area residents.

1,2-Dichloroethane

Exposure to 1,2-dichloroethane may have occurred in the past through skin contact with soil andsurface water, ingestion of contaminated soil and surface water, and possibly through the inhalationof contaminated air. Potential future exposure to 1,2-dichloroethane could occur to workers and off-site residents through inhalation if the appropriate safety measures employed during remediationshould fail. Health effects from exposure to 1,2-dichloroethane can occur from ingestion, inhalation,or dermal contact exposures. The specific adverse health effects depend on the dose, the duration,and the type of the exposure as well as the individual's sensitivity to the contaminant.

Ingesting high amounts of 1,2-dichloroethane can cause gastrointestinal disorders, circulatoryfailure, cardiac arrest, and death (Reference 15). Currently there are no chronic MRLs or RfDsavailable for 1,2-dichloroethane. Based on animal studies ATSDR has identified an acute MRL of0.005 mg/kg/day for immunological effects from exposure to this compound as well as intermediate(30 mg/kg/day) and chronic (25 mg/kg/day) NOAELs for adverse hepatic effects. We estimatedexposure scenarios for on-site workers, children who trespassed on the site, and adolescents whowere reported to have drunk water from area lakes. For children who periodically trespassed on thesite, the acute MRL for immunological effects was exceeded. Thus the possibility of adverse non-carcinogenic health effects exists. It is important to note that this MRL is based solely on animalstudies and that no causal link has been established between exposure and immunological effects inhumans. The lack of chronic MRLs or RfDs prevent us from fully evaluating the likelihood ofadverse health effects from chronic exposure.

Inhalation of 1,2-dichloroethane can be lethal to humans. Acute exposure to 400 ppm has resultedin death in rats and guinea pigs and in mice, rabbits, and dogs exposed to 1,500 ppm. The mostsusceptible organs in humans appear to be the lungs, liver, heart, and kidneys. Currently there areno chronic inhalation MRLs or RfDs available. However, using animal experiments, ATSDR hasidentified an acute MRL (0.025 ppm) for immunological effects from exposure to this compound. An intermediate inhalation NOAEL (100 ppm) for hepatic, renal, cardiovascular, respiratory, andreproductive effects has also been established. The lack of ambient air data prevent us fromevaluating the likelihood of adverse non-carcinogenic health effects from inhalation exposure to thiscompound.

Although 1,2-dichloroethane is considered a carcinogen, there is no specific evidence linkingexposure to this chemical with the occurrence of cancer in humans. While epidemiological studieson workers from the chemical industry suggest weak associations between inhalation exposure tothis chemical and cancer, there are no animals studies available to support this link. On the otherhand, exposure through ingestion and skin contact has caused cancer in laboratory animals.

Because of the carcinogenic effects observed with ingestion and skin contact, and the observedepidemiological associations with inhalation, the EPA considers 1,2-dichloroethane to be a probablehuman carcinogen. Calculations based on EPA's cancer slope factor for 1,2-dichloroethane foringestion show that all identified exposed populations would have no apparent increased lifetimerisk for developing cancer from exposure through ingestion. The lack of ambient air data prevent usfrom evaluating the lifetime cancer risk from inhalation.

Based on the above information, adverse health effects to children who frequently trespassed on thesite are possible. We were unable to evaluate the likelihood of non-carcinogenic adverse healtheffects either from chronic or from inhalation exposure. There is no apparent lifetime risk ofdeveloping cancer from exposure through ingestion. However, we were unable to evaluate thecancer risk due to inhalation.

1,2-Dichloropropane

Exposure to 1,2-dichloropropane occurred in the past through skin contact with and ingestion ofsurface water. As with the other volatile organic compounds, anecdotal evidence suggests that pastexposure from inhalation has likely occurred. Future exposure through inhalation is possible if thesafety measures used during remediation fail.

Although there are no health effects data available for repeated low level oral exposures in humans,ingestion of large quantities of 1,2-dichloropropane can result in death. Clinical signs ofoverexposure include primary effects on the central nervous system, liver, respiratory system, heart,blood, and kidneys (Reference 16). Specific causes of death included cardiac arrest and septicshock. Based on animal studies, ATSDR has identified a chronic MRL for ingestion of 0.07mg/kg/day. Using an exposure scenario for the adolescents who were reported to have drank waterfrom area lakes we estimate that the chronic MRL was not exceeded. Thus adverse non-carcinogenic health effects to these children from past ingestion are unlikely. Skin irritation aftercontact with 1,2-dichloropropane has been observed in both rabbits and humans; however, we wereunable to evaluate health risks from this type of exposure.

Inhalation of high levels of 1,2-dichloropropane has resulted in chest discomfort, dyspnea, andcoughing, indicating that this contaminant is a respiratory tract irritant in humans. In animalexperiments, the acute and chronic inhalation of low levels of this contaminant resulted in injury tovarious internal organs, while inhalation of high levels resulted in death. Short term exposures werealso noted to cause irritation to the eyes and throat. Based on animal research, ATSDR hasidentified an intermediate MRL (0.007 ppm) for inhalation exposure to this compound. The lack ofambient air data prevents us from evaluating the likelihood of adverse health effects from exposurethrough this route.

The ingestion or inhalation of 1,2-dichloropropane for short periods of time has not been reported toresult in cancer in humans. Conversely, long-term ingestion has resulted in liver cancer in mice andbreast cancer in female rats. The relationship between animal cancer studies using 1,2-dichloropropane and human health effects is not well understood. However, based on the EPA'scancer slope factor for ingestion, we estimate that these individuals have no increased lifetime riskfor developing cancer from exposure to this contaminant.

Although the available information suggests that adverse health effects from exposure to 1,2-dichloropropane are unlikely, the lack of ambient air data prevents us from evaluating the likelihoodof adverse effects due to past inhalation.

Vinyl Chloride

Exposure to vinyl chloride has occurred in the past through skin contact with and ingestion ofsurface water. Anecdotal evidence suggests that past exposure through inhalation may haveoccurred. Future exposure through inhalation of this contaminant is possible if the safety measuresused during remediation fail.

No studies were found associating adverse health effects with the ingestion of vinyl chloride inhumans. However, using animal studies, ATSDR has identified a chronic oral MRL for thiscompound of 0.00002 mg/kg/day (Reference 17). This MRL is based on a study in which chronicexposure of rats to vinyl chloride in their feed resulted in less serious adverse health effects to theliver. Using an exposure scenario for the adolescents who reportedly drank water from on-site lakes,we estimate that the chronic MRL was not exceeded. Thus, adverse non-carcinogenic health effects,to these individuals, from this exposure are unlikely.

No studies were located regarding adverse health effects and absorption of vinyl chloride through theskin. Animal studies suggest that exposure through this route is minimal and that adverse healtheffects are unlikely.

In humans, short-term high-level exposure to vinyl chloride through inhalation can cause dizziness,headache, loss of muscle coordination, unconsciousness, and death. Although there are no specificstudies measuring low-level effects of exposure to this compound, long-term, lower-level exposureshave been noted to cause what is referred as vinyl chloride disease. This is characterized by severeliver damage, effects on the lungs, effects on the fingers, thickening of the skin, and changes in theblood. In animals, exposure to vinyl chloride at very high levels in the air for short and long periodsof time has been found to effect the nervous system. Additionally, liver and kidney effects haveoccurred after high-level, short term inhalation exposures in animals.

There is an abundance of evidence suggesting that exposure to vinyl chloride can cause cancer. Occupational exposure of workers, through inhalation, has been associated with cancer of the liver,brain, central nervous system, lung, respiratory tract, and the lymphatic and blood making systems. Animal studies, have supported these associations. Although there are no studies associating theingestion of vinyl chloride with the development of cancer, feeding vinyl chloride to animals resultedin an increased incidence of cancer. Using EPA's cancer slope factor for ingestion of vinyl chloridewe estimate that the adolescents who reportedly drank from on-site lakes have no apparent increasedlifetime risk of developing cancer from this exposure. The lack of ambient air data prevents us fromevaluating the increased risk from inhalation exposure.

Although available information indicate that adverse health effects are unlikely, the lack of ambientair data prevents us from evaluating other exposures.

Bis(2-ethylhexyl)phthalate

Exposure to bis(2-ethylhexyl)phthalate (BEHT) has occurred in the past through skin contact withand ingestion of surface water. Acute ingestion of large quantities (10 grams) of BEHT can causegastrointestinal distress in humans (Reference 18). However, no other evidence was foundassociating the ingestion of this compound with adverse health effects in humans. Although ATSDRhas not identified an MRL for the ingestion of BEHT, the EPA has identified an RfD of 0.02mg/kg/day. Using an exposure scenario for the adolescents who reportedly drank from on-site lakes,we find that this RfD was not exceeded. Additionally, both animal and human studies have shownthat skin contact with BEHT does not cause any adverse health effects. Based on the aboveinformation, the development of non-carcinogenic adverse health effects is unlikely.

There is no direct evidence linking ingestion of BEHT with cancer in humans. However, severalchronic animal studies have shown ingestion of this compound to cause liver tumors in rats andmice. Based on animal studies the EPA has developed a cancer slope factor for ingestion of BEHT. Using this cancer slope factor, we estimate the exposed persons to have no increased lifetime risk fordeveloping cancer from this exposure.

Polychlorinated biphenyls

Exposure to polychlorinated biphenyls (PCBs) has occurred through skin contact with and ingestionof contaminated soil and surface water and through the ingestion of fish. Although no studies werefound pertaining to human exposure to PCBs, there is an abundance of animal data suggesting thatsuch exposure could lead to adverse health effects. Based on animal research, ATSDR hasidentified a chronic MRL of 0.005 g/kg/day for immunological effects from oral exposure to PCBs(Reference 19). We estimated exposure scenarios for on-site workers, children who routinelytrespassed on the site, the adolescents who reportedly drank from on-site lakes, and for persons whoroutinely caught and ate fish from areas where contaminated fish were found. The chronic MRLwas exceeded by all groups except the on-site workers. Thus, adverse non-carcinogenic healtheffects from this exposure are possible. It is important to reiterate that this MRL is based solely onanimal research and that no causal link has been established between exposure and immunologicaleffects in humans. Ingestion of PCBs has also been associated with adverse effects to the liver, theskin, the blood making system, and the gastrointestinal system. However, it is unlikely that theabove exposures would cause these effects.

Although there is no direct evidence associating oral exposure to PCBs with the development ofcancer in humans, animal studies have shown ingestion of this compound to cause cancer of the liverin animals. Using EPA's cancer slope factor for ingestion and exposure scenarios appropriate to theexposed populations, we estimate that on-site workers, children who routinely trespassed on site andpersons who routinely ate fish from the affected areas to have no apparent increased lifetime risk fordeveloping cancer. We estimate the adolescents who reportedly drank water from on-site lakes tohave a moderate increased risk.

Based on available information, carcinogenic and non-carcinogenic adverse health effects from PCBexposure are possible to adolescents who routinely drank from area lakes. It is important to notethat the actual exposure to these individuals is unknown and is likely much lower than our estimatedexposures. Thus, the risk of adverse health effects are likely much lower than those describedabove.

Beryllium

Exposure to beryllium may have occurred through ingestion and skin contact with on-site soil. Adverse health effects from exposure to beryllium have mainly been observed with inhalationexposure (Reference 20). There is no direct evidence associating oral exposure to beryllium withadverse non-carcinogenic health effects in humans. Additionally, there are few studies showingadverse non-carcinogenic health effects in animals from oral exposure. The EPA has identified anRfD for oral exposure to beryllium of 0.005 mg/kg/day. We estimate the exposure to on-siteworkers and to children who trespassed on the site to be below the RfD. Thus adverse non-carcinogenic health effects are unlikely.

Although ingestion of beryllium has not been reported to cause cancer in either animals or humans,experiments with animals inhaling beryllium (both soluble and insoluble compounds) showed thatlung cancer could be a health outcome. Based on these inhalation studies, the EPA has developed acancer slope factor for ingestion. Using this cancer slope factor we estimate that there is no apparentincreased lifetime risk for developing cancer from exposure to beryllium at this site.

Based on available information adverse health effects from exposure to beryllium at this site areunlikely.

Lead

Exposure to lead through ingestion of and skin contact with soil, has occurred among on-siteworkers and children who routinely trespassed on-site. Although not site related, exposure throughingestion may have occurred to residents drinking from residential wells in the RiverdaleSubdivision.

The highest historically reported lead concentration in residential drinking well water (45.2 g/L)was found to exceed the EPA's National Drinking Water Regulation action level of 15 g/L. WhileATSDR has no criteria for lead, lead exposure can cause adverse health effects. Adverse healtheffects include decreased neuro-behavioral functioning, slowed development of children, and effectson heme synthesis (Reference 21). Since lead accumulates in the body in soft tissues and bones andcan later be re-released into a person's system, it is difficult to calculate the exact dose received bychildren and adults ingesting lead contaminated soil or water. However, it has been found in somecases that typically 50% of the lead ingested is immediately eliminated through urine and bile. Blood lead levels can be easily measured, and give a fairly reliable indication of dose. For pregnantwomen and children, blood lead levels should be no greater than 10 g/dL, and for normal healthyadults no greater than 40 g/dL.

Exposure to lead is especially harmful to unborn children. A pregnant mother exposed to lead canhave a low birth weight baby, a prematurely born baby, or even abort the fetus. Lead has beenfound to lower intelligence quotient (I.Q.) scores, slow growth, and cause hearing problems inchildren. These adverse health effects in children can persist and can lead to decreased performancein school.

Lead has not been shown to be carcinogenic in humans. However, laboratory animals fed leadthroughout their life-spans have developed tumors. These data indicate a possibility that lead couldbe a human carcinogen.

High-level lead exposure can cause severe brain and kidney damage in adults and children. Leadexposure may increase blood pressure in middle-aged men. High level lead exposure may alsolower sperm counts in men through damage of the male reproductive system.

Based on recent sampling results exposure to lead via drinking water is not currently a problem.

B. HEALTH OUTCOME DATA EVALUATION

Because of the possible carcinogenic effects of several of the compounds of concern, we attempted toobtain cancer mortality data for the surrounding communities from the Texas Department of HealthCancer Registry Division. For reasons mentioned previously in the State and Local Health Datasubsection these data were not available. No other health outcome data were available forevaluation.

C. COMMUNITY HEALTH CONCERNS EVALUATION

We have addressed each of the community concerns about health as follows:

  1. Could the site be the cause of lung problems, skin rashes, eye problems, warts, mental retardation and baldness?

Although several of the contaminants found on site have been associated with lung problems, recentambient air data indicate that the concentrations of these contaminants in the air are too low to causeadverse health effects. It is important to note that the lack of ambient air data available during thetime when the site was active prohibits us from making any definitive estimates on past exposures.

Three of the contaminants found on site have been associated with skin irritation. These are PCBs,beryllium, and 1,2-dichloropropane. Although current exposures to these contaminants do notexceed ATSDR's MRLs, they may have in the past. Prior to the cleanup around Riverdale Lake andGulf Pump Road, PCB levels were high enough to cause adverse health effects. Previous exposureto volatile organic compounds, one of which is 1,2-dichloropropane, through ambient air may haveoccurred. There are two documented cases of worker skin contact with organic vapors resulting inskin rashes. Based on available data, it is unlikely that the site is responsible for current skin rashes.

The only contaminant reported to be associated with eye irritation in animals is 1,2-dichloropropane. Current ambient air concentrations of this contaminant are below the levels necessary to causeadverse health effects. It is possible that in the past, eye irritation occurred through exposure toambient air.

Exposure to lead can cause a decrease in IQ and subsequent learning disability; however, theexposures received on site are highly unlikely to cause mental retardation. No contaminants on site are known to cause warts or baldness.

  1. Will the emissions from the incinerator be harmful to children and pets?

The incineration process, which is designed to remove 99.99 percent of the contaminants, includesthe real-time monitoring of the stack emissions. In the event that stack emissions exceed monitoringstandards, all incineration activities will cease and corrective measures will be taken. Given thedesign of the incinerator and the safety measures employed, it is highly unlikely that emissions fromthe incinerator will be harmful to humans and/or pets.

  1. Will the incinerator be permanent?

The incinerator is portable and will be removed after remediation of the site is complete.

  1. Will odors and fallout result from the incineration process?

The collection of the ash and the destruction of the organic contaminants should prevent any odors or fallout from occurring.

  1. Will water from the site be dumped into the San Jacinto River and will it contaminate the fish?

The water which will be discharged into the San Jacinto River will have been treated to meet Statedischarge criteria. Water discharged at these levels will not result in fish contamination.

  1. Could the deaths from respiratory disease have resulted from exposure to sitecontaminants?

Several of the contaminants found on site have been associated with respiratory problems; however,recent ambient air data indicate that the levels of these contaminants in the air are too low to causeadverse health effects. It is important to note that there are no data available on levels of thesecontaminants in the air during the time when the site was active. Therefore, we cannot make anydefinitive estimates on past exposures.

  1. Could the site be responsible for mouth ulcers and upper respiratory and ear infections in a two-year-old child?

Exposure to both benzene and 1,2-dichloroethane could result in suppression of the immune systemthat could result in an increased susceptibility to infection. However, it is unlikely that this childwas exposed to benzene at concentrations that could cause the immunological effects. Therefore, itis highly unlikely that these site contaminants could have contributed to his ear infections.

  1. Could exposure to site contaminants be responsible for the slow development of atwo-year-old child, development being defined by the inability to talk yet?

Lead was the only contaminant on site which could contribute to slow mental development;however, this child could not have received on-site exposure since the site is now secured and thechild is too young to have been able to gain access to the site when it was more accessible. Earlyresidential well data report the residential well water for this household to be below the detectionlimit value of 20 g/L. Subsequent well water samples in December 1993 indicate that levels oflead found in Riverdale residential well water are below the Environmental Protection Agency'sPrimary Drinking Water Regulation action level of 15 g/L. Based on available data, it is unlikelythat site contaminants are responsible for the child's apparent slow development.

  1. Will there be medical waste and body parts burned in the incinerator?

No.

  1. Are the residential well and Municipal Utility District waters safe to drink?

The water from some of the residential wells in the Riverdale Subdivision may not be safe to drink. According to 1987 and 1989 data, lead and coliform groups of bacteria were found in some of theresidential well water at levels exceeding current health criteria. Available evidence suggests thatthe Sikes site is not the source of the lead contamination. The site is definitely not the source of thebacterial contamination. We have no data on the Municipal Utility District waters; however, site impact on these water supplies is unlikely.

  1. Can the site be responsible for the poor quality of water in Barrett (bad odor taste and discoloration)?

No. All the municipal wells in the Barrett area are reported to be screened at levels greater than 200feet. The contaminants from this site have not migrated off site.

  1. Can the site be responsible for the whole body swelling experienced by a resident after drinking water from Barrett?

No. None of the contaminants found on site are known to cause whole-body swelling. Additionally,none of the contaminants have been shown to have migrated off site.

  1. Can the site be responsible for the large amount of cancer that residents havereportedly observed in people living in the area?

The reported high rate of cancer is anecdotal and does not offer any specifics with respect to thetypes of cancers observed. Additionally, for reasons explained in this report, we were unable toobtain cancer morbidity or mortality data for this area. Although several of the site contaminantsare associated with increased cancer risks, the lack of specific cancer information makes itimpossible to infer any cause and effect relationship between site exposure and cancer at this time.

  1. Should the residents be concerned about having previously eaten fish and game taken from the site?

Fish taken from both the San Jacinto River and the Jackson Bayou were found to contain PCBs. Itis unlikely that previous exposures were great enough to cause adverse health effects. However,assuming that the fish are still contaminated, those persons who continue to eat fish caught fromthese waters should be concerned.

  1. Should residents be concerned about the fact that their children used to play on the site prior to the site being fenced?

Because of the nature and concentration of the contaminants found on site, adverse health effects arepossible. However, without information on the route of exposure, length of exposure, andchemical-specific exposure, it is impossible to predict the likelihood of adverse health effects.


CONCLUSIONS

  1. Although there is evidence of past exposure to site contaminants, the Sikes Disposal Pits sitecurrently poses no apparent public health hazard. Persons who may have been exposed in thepast include on-site workers exposed to organic vapors, a railroad worker who had directcontact with contaminated water and vapors, and children who ingested contaminated soil andwater. A review of the data collected during site investigations indicates that Riverdaleresidents may have been exposed to lead in well water in the past. The source of lead found inwell water in the past is unknown, but was probably not site related. Past exposure throughinhalation may have occurred to workers and residents in the surrounding communities during the time when the site was active.

  2. We were able to identify four past completed exposure pathways. These were: ingestion andskin exposure to on-site soil, inhalation of on-site air, ingestion of on-site water, and skin exposure to on-site water. Remedial actions have eliminated the danger of exposure through these pathways.

  3. We have received several health questions about this site from residents living near the Sikes Disposal Pits site. We have summarized and addressed these concerns in the Public Health Implications subsection of this document.

  4. Poisonous snakes and alligators are immediate threats to health on site. These are discussed in detail in the subsection entitled Physical and Other Hazards.

  5. Data inadequacies include the following:

    1. Lack of historical ambient air data.

    2. No readily available health outcome data.

RECOMMENDATIONS

  1. Protect persons on and off site from exposure to dusts or vapors that may be released during remediation.

  2. Provide on-site remedial workers with adequate protective equipment and training inaccordance with 29 CFR 1910.120, and follow appropriate National Institute for Occupational Safety and Health and Occupational Safety and Health Administration guidelines.

HEALTH ACTIVITIES RECOMMENDATIONS PANEL STATEMENT

In accordance with the Comprehensive Environmental Response Compensation, and Liability Act of1980, as amended, the data and information developed in the Sikes Disposal Pits Health AssessmentAddendum have been evaluated by the Health Activities Recommendations Panel (HARP) forappropriate follow-up health activities. The HARP determined that a fact sheet should bedistributed to the affected communities explaining their potential for exposure and the health effectsof lead. The Division of Health Studies concurred that if additional sampling indicates there iscurrent exposure to lead in drinking water, a biological indicators of exposure study may bewarrented. The HARP also concurred that in light of the close proximity of the French Limited NPLsite to the communities affected by the Sikes Disposal Pits site, any follow-up health activities couldaddress both sites simultaneously. If additional data become available suggesting human exposureto hazardous substances is occurring, ATSDR and TDH will reevaluate this site for additionalfollow-up activities.

When indicated by public health needs, and as resources permit, ATSDR and TDH will evaluate additional relevant health outcome data and community health concerns, as available.


PUBLIC HEALTH ACTION PLAN

The Public Health Action Plan (PHAP) for the Sikes Disposal Pits site contains a description ofactions to be taken by ATSDR and/or the TDH at and in the vicinity of the site subsequent to thecompletion of this Public Health Assessment Addendum. The purpose of the PHAP is to ensure thatthis Public Health Assessment Addendum not only identifies public health hazards, but also providesa plan of action designed to mitigate and prevent adverse human health effects resulting fromexposure to hazardous substances in the environment. Included is a commitment on the part ofATSDR and TDH to follow up on this plan to ensure that it is implemented.

Actions Taken

To fill a data need discovered during the development of this addendum, TDH analyzed watersamples for lead from 17 homes in the Riverdale subdivision. Analyses of water from first-drawindoor-faucet samples revealed lead ranging from <1.0 g/L up to 3.9 g/L. Of the 17 residences,five were unable to provide first-draw samples; for these homes water samples were taken from anoutside tap nearest the well. Well samples for these homes revealed lead ranging from <1.0 g/L upto 7.0 g/L. These levels are below the Environmental Protection Agency's Primary DrinkingWater action level of 15 g/L. Based on these results, no further health follow-up is indicated.

TDH and ATSDR will coordinate with state and federal environmental agencies to carry out therecommendations in this public health assessment addendum.


PREPARERS OF REPORT

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

Nicholas. J. Giardino, Sc.D.
Environmental Quality Specialist
Environmental Epidemiology Program

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

Nancy B. Ingram
Public Health Technician
Environmental Epidemiology Program

Leticia Cano
Secretary
Environmental Epidemiology Program


ATSDR REGIONAL REPRESENTATIVE

Carl Hickam, R.S.
Public Health Advisor
Regional Operations

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


ATSDR TECHNICAL PROJECT OFFICER

William Greim
Environmental Health Scientist
Division of Health Assessment and Consultation
Remedial Programs Branch
State Programs Section


CERTIFICATION

The Sikes Disposal Pits public health assessment addendum was prepared by the Texas Departmentof Health under a cooperative agreement with the Agency for Toxic Substances and DiseaseRegistry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health assessment was initiated.

William Greim
Technical Project Officer, SPS, RPB, DHAC


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

Director, DHAC, ATSDR


REFERENCES

1. Texas Department of Water Resources. July 1985. Sikes Disposal Pits, Crosby, Texas, RemedialInvestigation Volume I - Report. Submitted to Texas Department of Water Resources. Lockwood,Andrews & Newman, Inc., in Association with Environmental Science and Engineering, Inc.,Harding Lawson Associates.

2. Texas Department of Water Resources. July 1985. Sikes Disposal Pits, Crosby Texas. RemedialInvestigation Volume II - Appendices. Prepared by Lockwood, Andrews & Newman, Inc., inAssociation with Environmental Science and Engineering, Inc., Harding Lawson Associates.

3. Texas Water Commission. June 1986. Sikes Disposal Pits Crosby, Texas, RemedialInvestigation Volume III - Supplemental Report. Lockwood, Andrews & Newman, Inc., inassociation with Environmental Science and Engineering, Inc., Harding Lawson Associates.

4. Texas Water Commission. June 1986. Remedial Investigation Supplemental Sikes Disposal PitsSite. Vol. IV.

5. Texas Water Commission. July 1986. Sikes Disposal Pits, Crosby, Texas, Feasibility StudyReport. Prepared by Lockwood, Andrews & Newman, Inc., in association with EnvironmentalScience and Engineering, Inc., Harding Lawson Associates.

6. Record of Decision Remedial Alternative Selection. Sikes Disposal Pits, HWY 90, Crosby,Texas.

7. Texas Almanac, 1988-1989, Published by the Dallas Morning News.

8. Air Quality Impacts from the Sikes HTTS (draft). January 1991. Revised March 1991. ByIT-DAVY, Crosby, Texas.

9. Preliminary Interpretation of Ground Water Sampling Results. December 1987. By SuperfundProgram Branch, Environmental Protection Agency (EPA), Region VI, Dallas, Texas.

10. FLTG, Incorporated, Crosby, Texas, Post San Jacinto River May 1989 Flood Event Soils andWater Analysis Programs. June 1989 ENSR Consulting and Engineering (Formerly ERT).Document Number 2870-012-992.

11. FLTG, Incorporated, Crosby, Texas, Riverdale Lake Area Remediation Program. August 15,1989. ENSR Consulting and Engineering (Formerly ERT). Document Number 2870-012-992.

12. Lockwood, Andrews & Newman, Inc. letter dated January 7, 1986 and addressed to: Ms.Plitnik, from: Richard E. French, Project Manager.

13. ATSDR - Record of Communication dated October 19, 1988 to: George Buynoski, Chief, FieldOperation Branch, from: Carl R. Hickam, Senior Regional Representative, and George Pettigrew,Regional Representative.

14. ATSDR - Record of Communication dated July 15, 1988 to: George Buynoski, Chief, FieldOperation Branch, from: Carl R. Hickam, Senior Regional Representative and George Pettigrew,Regional Representative.

15. ATSDR. May 1989. Toxicological Profile for Benzene. U.S. Department of Health andHuman Service, Public Health Service, Agency for Toxic Substances and Disease Registry, AlantaGeorgia.

16. ATSDR. May 1989. Toxicological Profile for 1,2- dichloroethane. U.S. Department of Healthand Human Service, Public Health Service, Agency for Toxic Substances and Disease Registry,Alanta Georgia.

17. ATSDR. May 1989. Toxicological Profile for 1,2- dichloropropane. U.S. Department of Healthand Human Service, Public Health Service, Agency for Toxic Substances and Disease Registry,Alanta Georgia.

18. ATSDR. May 1989. Toxicological Profile for Vinyl Chloride. U.S. Department of Health andHuman Service, Public Health Service, Agency for Toxic Substances and Disease Registry, AlantaGeorgia.

19. ATSDR. May 1989. Toxicological Profile for Bis(2-ethylhexyl) phthalate. U.S. Department ofHealth and Human Service, Public Health Service, Agency for Toxic Substances and DiseaseRegistry, Alanta Georgia.

20. ATSDR. May 1989. Toxicological Profile for Polychlorinated Biphenyls. U.S. Department ofHealth and Human Service, Public Health Service, Agency for Toxic Substances and DiseaseRegistry, Alanta Georgia.

21. ATSDR. May 1989. Toxicological Profile for Beryllium. U.S. Department of Health andHuman Service, Public Health Service, Agency for Toxic Substances and Disease Registry, AlantaGeorgia.

22. ATSDR. May 1989. Toxicological Profile for Lead. U.S. Department of Health and HumanService, Public Health Service, Agency for Toxic Substances and Disease Registry, AlantaGeorgia.


SELECTED BIBLIOGRAPHY REFERENCES REVIEWED BUT NOT CITED

ATSDR. February 1991. Health Assessment Guidance Manual. U.S. Public Health Service,Agency for Toxic Substances and Disease Registry, Alanta Georgia.

Casarett and Doull's Toxicology, The Basic Science of Poisons. 1986. Editors: Klassen, C.D.,Amdur, M.O., Doull, J. 2nd Edition, MacMillion Publishing Company, New York, New York.

Texas Department of Water Resources. October 1988. Sikes Disposal Pits Crosby, Texas, RemedialDesign Sampling Program Final Report. Prepared by Lockwood, Andrews & Newman, Inc., inassociation with Environmental Science and Engineering, Inc., Harding Lawson Associates.

U.S. Environmental Protection Agency. February 17, 1988. Site Assessment Report for SikesDisposal Pits, Crosby, Harris County, Texas. Prepared by Ecology and Environmental, Inc.Technical Assistance Team.


APPENDICES

APPENDIX A: FIGURES

Site Location Map
Figure 1. Site Location Map

Sikes and Surrounding Communities Census Tract Locations
Figure 2. Sikes and Surrounding Communities Census Tract Locations

Important Features of the Site
Figure 3. Important Features of the Site

Well Locations Around the Area
Figure 4. Well Locations Around the Area

Waste Survey Areas
Figure 5. Waste Survey Areas

Waste Sampling Locations
Figure 6. Waste Sampling Locations

Core Soil Sampling Locations
Figure 7. Core Soil Sampling Locations

Sediment Sampling Locations
Figure 8. Sediment Sampling Locations

On-Site Surface-Water Sampling Locations
Figure 9. On-Site Surface-Water Sampling Locations

On-Site Shallow Ground-Water Contamination and Sampling Locations
Figure 10. On-Site Shallow Ground-Water Contamination and Sampling Locations

Off-Site Near-Surface Soil Sampling Locations
Figure 11. Off-Site Near-Surface Soil Sampling Locations

Off-Site Surface Water, Sediment and Fish Sampling Locations Soil Sampling Locations
Figure 12. Off-Site Surface Water, Sediment and Fish Sampling Locations Soil Sampling Locations


APPENDIX B: DEPARTMENT OF HEALTH AND HUMAN SERVICES MEMORANDUM, DATED APRIL 24, 1986

Date: Apr 24, 1986

From: Acting Director
Office of Health Assessment

Subject: SI 85-131 and SI 86-019, Sikes Disposal Pits, Crosby, Texas

To: Mr. Carl R. Hickam
Public Health Advisor
EPA Region VI

EXECUTIVE SUMMARY

The Agency for Toxic Substances and Disease Registry (ATSDR) was requested to review the Sikes Disposal Pits Remedial Investigation Reports to identify areas of public health significance and provide comments on the setting of cleanup objectives for the site. Extensive sampling revealed that the shallow groundwater, surface water, soils, and sediments were contaminated with heavy metals and volatile organic compounds.

The Environmental Protection Agency (EPA) has proposed to clean up the contaminated material according to the distribution of a number of marker compounds (benzene, toluene, ethylbenzene, pyrene, 1,1,2-trichloroethane, lead, fluorene, l,2-dichloroethane, and naphthalene) in sludges and soils identified in the sampling efforts to a proposed cleanup level of 10 ppm.

ATSDR believes that these proposed cleanup levels are adequate for the protection of public health, considering the present and known future uses (i.e., marina) of the site and proximal areas. The impact on public health would have to be reconsidered should any future uses offer the opportunity for increased public exposure to residual contamination. We have included a number of recommendations for monitoring the migration of the remaining material after cleanup and other considerations; these are outlined in the "Recommendations" section.

BACKGROUND

ATSDR was requested by the EPA, Region VI, to review the Sikes Disposal Pits Remedial Investigation Reports to identify areas of public health concern and provide comments on the setting of cleanup objectives for the site.

The 185-acre Sikes Disposal Pits site is located in northeast Harris County, approximately 2 miles from Crosby, Texas. It is bordered by the San Jacinto River on the west side and the Jackson Bayou on the north side. The area immediately surrounding the site is largely undeveloped with numerous active and abandoned sand pits and low-lying swampy areas. The site's ponds and/or adjacent areas are reportedly used by the local population for sport fishing, swimming, boat launching, water skiing, off-road vehicle racing, target practice, debris/garbage scavenging, and sand mining operations. With the exception of Mr. Sikes' abandoned dwelling next to Tank Lake and the trailers next to U.S. 90 that he and his two sons currently live in, the closest residential development is the Riverdale Subdivision which lies southeast (500 feet) of the site and contains about 100 persons. Additional homes lie along Gulf Pump Road just south (500 to 750 feet) of the site and U.S. Highway 90.

Disposal operations on the site occurred from the early 1960s to 1967 when the site was closed. A variety of chemical wastes were disposed in unlined sand pits on-site. The entire site contains numerous drums in deteriorated condition. About 600 drums lie in a 1-acre area northeast of the mine waste pit; waste spills from the drums are evident.

The site lies within the 100-year floodplain of the San Jacinto River and portions of the site lie within the 10- and 50-year floodplains. At least four floods have completely inundated the site since 1969. During one of these episodes, the primary disposal pit was overtopped and breached, resulting in the spread of organic sludge waste over approximately 8 acres. In addition, rainwater is discharged from the main waste pit through this overflow area and ultimately into the San Jacinto River. Only during periods of flooding do the small waste pits discharge to the surface water.

There are adjacent sand mining operations which have influenced (increased) the normal groundwater gradients toward the San Jacinto River. There does not appear to be any contamination from the site in the river at this time. It is hypothesized that curtailing the dewatering of the active sand pits will result in a change in gradient toward the Riverdale Subdivision. However, the San Jacinto River ultimately receives the groundwater from the site.

There are two groundwater aquifers beneath the site referred to in the report as the Upper and Lower Aquifers. The Upper Aquifer is heavily contaminated and at least seven local residents rely on the Upper Aquifer for drinking water. The Lower Aquifer contains trace levels of some volatile organics including benzene, vinyl chloride, and chlorinated benzenes, although it is not clear that this contamination is due to the Sikes site. Furthermore, core samples of the Aquitard (the highly plastic clay strata separating the two aquifers) indicate that no apparent migration of contaminants has occurred through the Aquitard. There are two deeper aquifers, the Chicot and the Evangeline, which serve as the water supply for Metropolitan Houston, Texas. These aquifers do not appear to be contaminated at this time.

Forty production wells have been identified within approximately 3 miles of the site. Two of these wells are within a mile of the site, the closest well (#1148; Evangeline aquifer) lies 4000 feet to the southwest. Of the 40 wells, 18 wells lie within 2 miles of the site (east, north, northeast, and west). An additional 30 private residential wells have also been found to lie immediately south or southeast of the Sikes site which is in the direction of the groundwater flow from portions of the site. At least two of these residential wells (map reference #53 and #69) are quite shallow (24 and 25 feet deep, respectively) and lie less than 300 feet (#53) and 700 feet (#69) from the Sikes' property line. These two wells and any other shallow local well not having the benefit of a sufficient "Aquitard" stratum are potentially subject to surface contamination. However, many of the 30 additional residential wells found lie in the Lower Aquifer or deeper aquifers which have not had evidence of contamination.

A plan has been developed which will use "marker" compounds - chemical substances which predominated the samples in both frequency and quantity - to establish the level of cleanup. The plan is to remove the contaminated sludges and underlying soil until no more than 10 ppm of any of the marker compounds remain.

A preliminary list of objectives and governing criteria was established. These nine objectives considered preventing the use of contaminated groundwater, contamination of the lower aquifer, San Jacinto River, and Jackson Bayou, minimizing and preventing human contact with contaminated surface water, soils and sediments, and minimizing the potential for adverse air discharge during cleanup.

DOCUMENTS REVIEWED

  1. Remedial Investigation Report, Volumes I and II, July 1985, submitted by Lockwood, Andrews and Newnam, Inc., for the Texas Department of Water Resources.

  2. Remedial Investigation Report, Volume III and IV, January 1986, submitted by Lockwood, Andrews and Newnam, Inc., for the Texas Department of Water Resources.

  3. Unsummarized data collected from the Sikes site collected in July 1985.
  4. These documents cover three separate investigative sampling efforts: May-June 1983, February 1984, and July-August 1985.

    Some aspects of this site have been commented on previously. On January 24, 1985, we commented on the advisability of continuing the sand mining operations adjacent to the site. On April 30, 1985, we commented some of the preliminary data concerning the site. These memoranda are attached.

    We also were provided with additional information via teleconference with the EPA Project Manager and the Regional Public Health Advisor on January 3, 1986, and during a site visit on February 6, 1986.

    Additional data were provided November 18, 1985. However, some of these data were duplicates of previously provided data. Since no locator map could be found to allow us to accurately use the remaining data, these data are not included in the health assessment.

CONTAMINANTS OF CONCERN

The primary contaminants on the site are aromatic hydrocarbons, chlorinated aliphatic hydrocarbons, polychlorinated biphenyls, polynuclear aromatic hydrocarbons, and heavy metals. In order to establish a guide for cleanup operations, it was decided to concentrate on selected individual compounds. Based on the core data obtained beneath the waste sludges, the "marker" compounds for soil cleanup are benzene, 1,2-dichloroethane, toluene, 1,1,2-trichloroethane, naphthalene, and lead. Based upon the analysis of the sludge data, the "marker" compounds for sludge removal are toluene, ethylbenzene, naphthalene, fluorene, pyrene, and lead.

  1. Benzene. The toxic effects of benzene are well documented and a review of these properties can be found in the EPA's Health Advisory (1). Benzene has been classified as a carcinogen by the Occupational Safety and Health Administration (OSHA) (2), the International Agency for Research on Cancer (IARC) (3a,b,c), the National Toxicology Program (NTP) (4), the National Institute for Occupational Safety and Health (NIOSH) (5), and the American Conference of Governmental Industrial Hygienists (ACGIH) (6). The EPA health advisory for benzene calls for a 10-day limit in drinking water of 233 ug/L (ppb). The 105 cancer risk estimate developed by EPA is 7 ug/L in drinking water.

  2. Toluene. The EPA health advisory provides a good summary of the toxic effects of toluene (7). Other references include the NIOSH criteria document (8), and Patty's Industrial Hygiene and Toxiology (9). The 10-day health advisory is 6,000 ug/L in drinking water. A cancer risk estimate has not been developed since there is no evidence to date that toluene acts as a carcinogen. The drinking water equivalent level for lifetime consumption considering noncarcinogenic effect is 10.8 mg/L.

  3. Vinyl chloride. EPA also has published a health advisory on vinyl chloride (10). IARC, NIOSH, OSHA, NTP, and ACGIH all consider vinyl chloride to be a carcinogen. The 10-day health advisory for vinyl chloride in drinking water is 2,600 ug/L; longer tern exposure from drinking water should be limited to 13 ug/L. The 105 cancer risk estimate is 0.15 ug/L for drinking water.

  4. 1,2-Dichloroethane. EPA has classified 1,2-dichloroethane or ethylene dichloride as a carcinogen based on animal studies (11). However, IARC has not classified ethylene dichloride into a category as to its carcinogenic potential and NTP only considers it in a class reasonably anticipated to be carcinogenic. The occupational health agencies have not considered ethylene dichloride a carcinogen. The 10-day health advisory for drinking water is 740 ug/L and longer term drinking water exposure should be limited to 2,600 and 740 ug/L for a 70 kg adult and 10 kg child, respectively. While EPA is in the process of reviewing the estimated excess cancer risk associated with l,2-dichloroethane, the earlier estimate for 105 cancer risk is 9.5 ug/L for drinking water.

  5. 1,1,2-Trichloroethane. No EPA health advisory has been developed for 1,1,2-trichloroethane. The literature contains some toxicity information (12-14), but the animal exposure data are generally confined to inhalation and, to a lesser extent, skin absorption. The levels of exposure are generally greater than those to which the public would be exposed. The principal physiologic responses to l,1,2-trichloroethane are depression of the central nervous system and liver injury. It can be absorbed through the skin. The National Cancer Institute has determined 1,1,2-trichloroethane to be a carcinogen in the mouse (16). As presented by EPA (13), an additional lifetime cancer risk of 105 is posed by a concentration of 6.0 ug/L in drinking water.

  6. Ethylbenzene. EPA has developed a health advisory for ethylbenzene (17). There is inadequate data to evaluate carcinogenicity. The 10-day health advisory is 2,100 ug/L (child) for drinking water and the lifetime drinking water equivalent level for noncarcinogenic outcomes is 3,400 ug/L for an adult.

  7. Polynuclear aromatic hydrocarbons (PAHs). A number of PAHs have been detected in the various samples collected at the Sikes site, including pyrene, fluorene, and naphthalene. Since PAHs have been determined to be carcinogenic, it is generally considered that all PAHs are likely to be carcinogenic. A drinking water standard for PAHs has been developed. The additional lifetime cancer risk of 105 is posed by a concentration of 0.028 ug/L if food is a source of PAHs, and 0.031 ug/L if intake is by water alone (14).

  8. Lead. The EPA health advisory (20) reports a lifetime health advisory (intake from all sources) of 20 ug/day, in order to protect any age group (children under 2 years are most susceptib1e) in extended periods of exposure. The maximum level allowed in drinking water is 50 ug/L.

ENVIRONMENTAL PATHWAYS

The predominant pathways for human exposure from the contaminants from the Sikes Disposal Pits are contact with surface runoff during times of flooding and ingestion of contaminated groundwater. Minor potential pathways include contact, ingestion, or inhalation of contaminated soil particles by persons engaged in activities on-site or engaged in operations adjacent to the site (sand mining). Ingestion of contaminated groundwater is limited at the present time to those people whose wells tap the Upper Aquifer. If this site is allowed to persist unabated and the Lower Aquifer becomes further contaminated, then more people will be affected.

DATA SUMMARY

The data from this site best can be summarized by grouping the "marker" compound data by date of sampling effort and by type of sample (shallow groundwater, surface water, soil, and sediment).

A. July 1983 and February 1984 Sampling Effort

  1. Shallow groundwater near the main waste pit: benzene 10,000 ppb, ethylbenzene from 700 ppb, 1,2-dichloroethane 2,200 ppb, and toluene 750 ppb. In addition, vinyl chloride was measured at 100 ppb and total phenols 15,000 ppb. Further, groundwater around the sludge overflow area showed maximum concentrations of benzene 2,200 ppb, chlorobenzene 10 ppb, 1,l-dichloroethane 20 ppb, ethylbenzene 56 ppb, toluene 110 ppb, trans-1,2-dichloroethene 160 ppb, and vinyl chloride 220 ppb.

  2. Shallow groundwater away from main waste pit: benzene 890 ppb, 1,2-dichloroethane 330 ppb, naphthalene 52 ppb, and fluorene 5 ppb. Also, vinyl chloride was measured at 190 ppb.

  3. Deep groundwater: trace organic compounds (1,1-dichloroethane 3 ppb, bis(2-ethylhexyl)phthalate 36 ppb, chlorobenzene 2 ppb, di-N-octylphthalate 6 ppb).

  4. Surface water from main and small waste pits: benzene 27 ppb, 1,2-dichloroethane 91 ppb, toluene 14,300 ppb, 1,1,2-trichloroethane 7 ppb, fluorene 3 ppb, and pyrene 190 ppb. PCBs were measured at 153 ppb also.

  5. Surface water downstream from main waste pit: 1,2-dichloroethane 73 ppb, and l,l,2-trichloroethane 21 ppb.

  6. Jackson Bayou and San Jacinto River: benzene 27 ppb and total phenols, 69 ppb.

  7. Tank Lake: 1,2-dichloroethane 13 ppb.

  8. Sediments from main and small waste pits: lead 604 ppm, chromium 139 ppm, mercury 4 ppm, copper 288 ppm, total phenols 15,100 ppm, naphthalene 570 ppm, fluorene 120 ppm, benzene 18 ppb, 1,2-dichloroethane 49 ppb, ethylbenzene 52 ppb, phenanthrene 100 ppm, acenaphthene 58 ppm, and toluene 66 ppb.

  9. Sediments from Tank Lake: benzene 7 ppm, 1,2-dichloroethane 10 ppm, ethylbenzene 14 ppm, toluene 15 ppm, naphthalene 70 ppm.

  10. Sediments from Jackson Bayou and San Jacinto River: no marker compounds identified.

  11. Active sand pits and drainageways off the site: no marker compounds identified.

  12. Soil cores from overflow area: total phenols 940 ppm, benzene 78 ppm, 1,2-dichloroethane 250 ppm, 1,1,2-trichloroethane 86 ppm, phenol 71 ppm, naphthalene 1,400 ppm, fluorene 230 ppm.

  13. Fish tissue from Jackson Bayou and from San Jacinto River: no marker compounds detected.

B. July 1986 Sampling Effort

  1. Groundwater from near main waste pit: benzene 9,200 ppb, chlorobenzene 390 ppb, chloroform 75 ppb, 1,1-dichloroethane 1,000 ppb, ethylbenzene 1,000 ppb, toluene 4,300 ppb, trans-1,2-dichloroethene 900 ppb, vinyl chloride 400 ppb, ethyl benzene 140 ppb, and naphthalene 5,900 ppb.

  2. Groundwater away from main waste pit: benzene 250 ppb, ethylbenzene 14 ppb, toluene 17 ppb, chlorobenzene 22 ppb, 1,l-dichloroethane 99 ppb, chloroform 24 ppb, acenapthene 24 ppb, trans-1,2-dichloroethene 14 ppb, and vinyl chloride 160 ppb.

  3. Deep groundwater: trace organic compounds (benzene, chlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane).

  4. Sediments from main and small waste pits: toluene 93,000 ppm, ethylbenzene 100,000 ppm, naphthalene 1,200,000 ppm, fluorene, 290,000 ppm, pyrene 590,000 ppm, and lead 11,000 ppm, benzene 81,000 ppm, fluoranthene 330,000 ppm, 1,2-dichloroethane 63,000 ppm, chromium 97 ppm, and zinc, 95 ppm.

  5. Sediments from Tank Lake: PCBs 120 ppm, lead 43 ppm, benzene 4,900 ppm, l,2-dichloroethane 1,800 ppm, ethylbenzene 1,000 ppm, toluene 4,100 ppm, vinyl chloride 140 ppm, and barium 54 ppm.

  6. Soil cores from overflow area: benzene 320,000 ppb, 1,2-dichloroethane 1,000,000 ppb, 1,1,2-trichloroethane 500,000 ppb, naphthalene 940,000 ppb, toluene 79,000 ppb, and lead 64,000 ppb.

HEALTH ASSESSMENT

The levels of contamination in the various media have increased in several locations from the time of the first sampling effort in July 1983 until the last effort in July 1985, as the following illustrates.

Groundwater: benzene from 1 to 250 ppb, chlorobenzene from 1 to 22 ppb, 1,1-dichloroethane from 4 to 99 ppb, trans-1,2-dichloroethene from 2 to 14 ppb, and vinyl chloride from 2 to 160 ppb. These data are taken from a well which is situated between the site and the active sand pits to the south. This increase is most likely due to the dewatering program in the sand pits, which influences the natural groundwater gradients.

Groundwater: benzene from 1 to 14 ppb, chloroform from 1 to 24 ppb, acenapthene from 4 to 24 ppb, chlorobenzene from 1 to 11 ppb, ethylbenzene from 2 to 14 ppb, and toluene from 1 to 17 ppb, due to increased groundwater gradients to the west toward the Bayou and River.

Groundwater: benzene from 1 to 26 ppb, and 1,1-dichloroethane from 1 to 25 ppb to the northeast of the main pit and overflow area.

These data indicate that the groundwater contamination on the Sikes site is moving in general toward Jackson Bayou and the San Jacinto River. The data from the groundwater monitoring wells located farthest from the site boundries, imply that the contamination has not migrated significantly beyond the 10 ppm benzene isogram illustrated in Figure 4-7 of volume III (page 96). Two wells indicated levels of lead higher than the drinking water standard of 50 ug/L (samples GW 19 and 22).

The data gathered from the Riverdale Subdivision indicate that significant contamination has not reached there. Riverdale soils from areas susceptible to receiving floodwater from the site were found to contain chloroform at 13 to 43 ppb and bromodichloromethane at 13 to 23 ppb, along with 210 to 520 ppb bis(2-ethylhexyl)phthalate. Soils not subject to site floodwater contained 260 to 300 ppb bis(2-ethylhexyl)phthalate. The groundwater gradients in the western Riverdale area created by the sandpit dewatering are sufficient to prevent contaminant migration in this direction so far. However, should the dewatering activity cease or change, migration patterns also may change.

We agree with the conclusion of the Remedial Investigation report that, if left in place, the wastewater and sludges from the Sikes site will continue to contaminate the groundwater and will eventually find its way into the San Jacinto River, thereby threatening the water supply for Houston, Texas. Also, vertical migration of material may eventually breech the Aquitard and allow contamination of the Lower Aquifer. Episodes of flooding will continue to spread the sludges. Dewatering of active sand pits causes significant changes in the groundwater gradients in the area and could cause contamination to spread into Riverdale Subdivision. Human traffic through the site for the various activities outlined previously will offer the opportunity for contact with the contaminated material.

The proposal is to clean up the contaminated material according to the distribution of a number of marker compounds (benzene, toluene, ethylbenzene, pyrene, l,1,2-trichloroethane, lead, fluorene, 1,2-dichloroethane, and naphthalene) in sludges and soils identified in the sampling efforts to a proposed level of cleanup of 10 ppm. Cleanup of contaminated surface water was not specifically mentioned in any report or conversation. We assume that contaminated surface water will be treated in some fashion.

Our major concerns are the identification of all areas of contamination so that they are included in the cleanup effort, the disposition of contaminated surface waters, and the potential future uses of the site which might result in human contact with remaining contamination.

The following are recommendations concerning additional sampling, monitoring, and other aspects of this site.

RECOMMENDATIONS

  1. The proposed 10 ppm cleanup level should be sufficient to protect public health considering the present and known future uses of the site and proximal areas. The residual contamination and its impact on public health should be considered in the selection of any future uses which would offer the opportunity for increased public health exposure.

  2. A monitoring program should be established for those residential wells using the upper and lower aquifers for drinking water in order to monitor for any changes in flow direction and contaminant spread. Although these wells may be upgradient to the site, the dewatering operations have such an influence on the local gradients that it is not clear to us that the wells will continue to be upgradient.

  3. Additional efforts should be made to identify all local private wells and their water sources.

  4. Additional sediment samples should be taken in the drainage ditches, flood flow channel, and the retention area adjacent to U.S. 90. Piles of dredged sediments were observed at the end of Gulf Pump Road on the bank of the San Jacinto River next to the U.S. 90 bridge during our site visit. Because these materials may have been contaminated by wastes transported from the site, the origin and ultimate deposition of these sediments should be determined. Because of the proximity of these materials to the site, they should be sampled and analyzed. Recent dredged piles of sediments containing organics were observed next to an abandoned sand pit and clamshell equipment about 250 feet north of the on site overflow area. It was indicated that this sand pit had not been sampled because it was thought to be clean. We noticed strong organic odors associated with these piles. Since the pit is located close to the overflow area, we suggest that the organic sediments be sampled and analyzed.

  5. Since contaminant seeps have been noted in the unused sand pits adjacent to active sand pits, the disposition of the water pumped from those inactive sand pits, as well as the disposition of the sand itself, should be determined if the pits become active again. Efforts should be implemented to prevent further leaching.

  6. If the plans for a marina in the Love Sand Pits area materialize, consideration should be given to a method for preventing the contact with and the spread of contaminants from the seeps to people and bodies of water such as the Bayou and River. The installation of a marina will hasten the spread of contaminants via surface water exchange. A surface water monitoring program may be necessary in order to gauge the impact that remaining contamination may have on the Jackson Bayou and San Jacinto River. Further, one of the objectives and attendant criterion is to prevent human contact with contaminated surface water, with the definition of contaminated being any surface water in excess of the Texas regulations for wastewater discharges (24). Consideration should be given to the future uses of the remaining sand pit water and whether or not meeting these regulations is appropriate for these uses. The State may require more stringent quality levels than those specified to ensure protection of receiving waters, i.e., State water quality standards (25). If any ponds on the site will be used in the future for public fishing or contact recreation, the criteria established for surface waters should consider aquatic life toxicity and bioconcentration, and potential human exposure through water contact (dermal with some water ingestion), and ingestion of contaminated aquatic organisms.

  7. The objective concerning minimizing fugitive air emissions uses the OSHA standards as the governing criteria for the protection of cleanup workers. There are two groups of people to consider in this respect: workers who will clean up the site, and the public who lives adjacent to the site. For the former group, we call your attention to the American Conference of Governmental Industrial Hygienists' Threshold Limit Values and Supporting Documentation and the National Institute for Occupational Safety and Health's Recommended Exposure Limits. These are two sources of more up-to-date exposure level limits available for comparison. We suggest that you adopt the lowest exposure limit for a particular chemical since this will give the greatest margin of safety. For the latter group, there may be either State or EPA ambient air quality standards that would apply.

  8. The criterion to determine the acceptability of using contaminated shallow and deep groundwater will be comparison to background water samples. The constituents of this background sample should not exceed State or Federal drinking water standards. If background samples are found to exceed these Federal or State standards, individuals using those sources for drinking water should be notified that their water does not meet these standards.

  9. Since you have indicated that exposure problems were experienced during site-invasive activities (drilling) of the remedial investigation (letter dated January 7, 1986, from the site investigator to EPA), we recommend that level B personal protective equipment be used for all site-invasive activities such as well installation and core sampling.

  10. The abandoned oil well suspected of causing at least some cross contamination between the upper and lower aquifers should be inspected to determine if it has been capped and capped properly.

  11. All future wells should be constructed so that cross contamination would be prevented.

  12. The landfill area should be posted in order to warn potential users of the area against water and soil contact and fishing in the bodies of water on-site until corrective action has been implemented. If possible, restricted access should be instituted. Consideration should be given to the future uses of this land and the impact the remaining contamination would have on this use. We recognize the restrictions inherent in being in the floodplains.

Jeffrey A. Lybarger, M.D.


REFERENCES

  1. Environmental Protection Agency. Office of Drinking Water, Health Advisory Program: Health Advisories for Various Substances. Draft Advisories published in 1985.

  2. Occupational Safety and Health Administration. OSHA safety and health standards. 29 CFR 1910.1000. Occupational Safety and Health Administration, revised, 1982.

    1. World Health Organization. International Agency for Research on Cancer (IARC) Monographs on the evaluation of the carcinogenic risk of chemicals to humans. Chemicals, industry processes and industries associated with cancer in humans. International Agency for Research on Cancer Monographs. Vol. 1 to 29, Supplement 4: Geneva, 1982.

    2. World Health Organization. International Agency for Research on Cancer (IARC) Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Vols. 30-34, 1983 to 1984.

    3. World Health Organization. International Agency for Research on Cancer: Handling Chemical Carcinogens in the Laboratory, Problems of Safety. International Agency for Research on Cancer Scientific Publications No. 33, 1979.

  3. U.S. Department of Health and Human Services. National Toxicology Program, Third Annual Report on Carcinogens, 1983.

  4. National Institute for Occupational Safety and Health. Criteria for Recommended Standards: occupational exposure to various chemical substances and processes. Cincinnati, Ohio: National Institute for Occupational Safety and Health.

  5. American Conference of Governmental Industrial Hygienists. Threshold Limit Values for Chemical Substances and Physical Agents in the Workroom Environment with Intended Changes for 1986. Cincinnati, Ohio: ACGIH, 1986.

  6. Op cit, EPA Health Advisories.

  7. National Institute for Occupational Safety and Health. Criteria for a Recommended Standard: occupational exposure to toluene. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1973. [DHEW (NIOSH) Publication No. 73-11023].

  8. Patty, FA. Patty's Industrial Hygiene and Toxicology. Vol. II--Toxicology, 3rd. revised edition. New York: John Wiley & Sons, Inc., 1981.

  9. Op cit., EPA Health Advisories.

  10. Op cit., EPA Health Advisories.

  11. Op cit., Patty, vol. IIB, pg. 3510.

  12. Environmental Protection Agency. Guidance on Feasibility Studies Under CERCLA. Office of Research and Development, USEPA. Cincinnati, Ohio: Environmental Protection Agency, June 1985. EPA/540/G-85/003.

  13. Op cit., EPA Guidance on Feasibility Studies Under CERCLA.

  14. Sax, NI. Dangerous Properties of Industrial Materials. 6th edition, New York, Van Nostrand Reinhold Company (1984).

  15. U.S. Department of Health and Human Services. National Cancer Institute Bioassay of 1,1,2-Trichloroethane for Possible Carcinogenicity. Technical Report Series #74, Bethesda, MD (1978).

  16. Op cit., EPA Health Advisories.

  17. Environmental Protection Agency. Guidance on Feasibility Studies Under CERCLA. Office of Research and Development, USEPA. Cincinnati, Ohio: Environmental Protection Agency, June 1985. EPA/540/G-85/003.

  18. Op cit., EPA Health Advisories.

  19. Op cit., EPA Health Advisories.

  20. National Institute for Occupational Safety and Health. Criteria for a recommended Standard... occupational exposure to Chromium VI. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1976. [DHEW (NIOSH) Publication No. 76-129].

  21. Op cit., EPA Health Advisories.

  22. Op cit., EPA Health Advisories.

  23. Texas Administrative Code 31, Natural Resources and Conservation, Part X-Texas Water Development Board, Chapter 329- General Regulations Incorporated into Permits, Monitoring and Reporting System, August 10, 1984.

  24. Texas Administrative Code 31, Natural Resources and Conservation, Chapter 333- Water Quality Management, Sections 11-21, Surface Water Quality Standards, updated March 28, 1985.

Table of Contents

  
 
USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

A-Z Index

  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #