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PUBLIC HEALTH ASSESSMENT

MRI CORPORATION
TAMPA, HILLSBOROUGH COUNTY, FLORIDA


ENVIRONMENTAL CONTAMINATION

A. On-Site Contamination

To evaluate contaminants in soil, sediment and groundwater, the maximumconcentrations of all contaminants were identified and were compared with the ATSDRscreening values to choose chemicals for further evaluation (Table 1A-1D, AppendixB). If the maximum contaminant concentration exceeded the ATSDR screening value,the contaminant was retained for further evaluation. If the maximum contaminantconcentration was less than the screening value, it was eliminated from furtherevaluation. If ATSDR did not have a screening value for a contaminant, thecontaminant was retained for further discussion. Iron, magnesium, calcium, potassiumand sodium because they are essential to human nutrition (7). The contaminantsretained for further evaluation are called the chemicals of concern. Classifying a contaminant as a chemical of concern does not necessarily mean exposure to thiscontaminant will be associated with illness. It simply serves to narrow the focus of thispublic health assessment to those compounds most likely associated with humanexposure at levels above health guidelines (Table 1A-1D, Appendix B).

We defined the on-site boundary as the area within the fence and the ditch outside ofthe fence on the east side (Figure 3, Appendix A). In 1984, FDER tested MRI's wastewater and found oil and grease, mercury, cyanide and cadmium. The results were notavailable. In July 1990, EPA found cyanide, chromium, lead, nickel, manganese,mercury, and zinc above background levels in the surface and subsurface soil (Table1A and 1B, Appendix B). They found elevated levels of organic chemicals in thesediments (Table 1C, Appendix B). A variety of polyaromatic hydrocarbons (PAH),trichloroethene, dieldrin and Aroclor 1254 were also present. EPA also found cyanidein the groundwater (Sampling locations are in Figure 3 and results are in Table 1D). In1992, the EPA found antimony, chromium, aluminum, lead, and manganese in surfacesoil above background and screening levels. In subsurface soil, aluminum was abovebackground and screening levels (2,5). Private wells in Orient Park, north of the site,have not been tested for metals or cyanide (6). Surface water data was not available.

B. Off-site Contamination

The off-site area includes the area outside of the fence in Figure 3, excluding the ditchbetween the fence and railroad tracks on the east side. Available data for inclusion inthis PHA does not include any off-site sampling.

C. Quality Assurance and Quality Control

In preparing this assessment, we relied on the information provided in the referenceddocuments. We assume that adequate quality assurance and quality control measureswere followed regarding chain of custody, laboratory procedures, and data reporting. The analyses, conclusions, and recommendations in this PHA are valid only if thereferenced documents are complete and reliable.

D. Physical and Other Hazards

There are no obvious physical hazards at the site. To find industrial facilities that couldadd to the contamination near the MRI Corporation site, the 1987-1993 EPA ToxicChemical Release Inventory (TRI) database was searched. EPA developed TRI fromthe chemical release information (air, water, and soil) provided by certain industries. We found thirteen facilities in the 33619 ZIP code reported releases from 1987-1993. This ZIP code covers a rectangular area about 1.5 miles north and east, 3 miles west,and 5 miles south of MRI. Facilities which reported releases of contaminants that areof concern at MRI include Trademark Nitrogen Corporation, This facility is 508 feetsouthwest of MRI and released manganese and zinc into the air. If people are exposedto contamination from MRI, exposures to compounds in air from other sources couldcontribute to their total exposure. No data is available to assess exposure to thesecompounds.

Other facilities outside the one-mile radius from MRI which reported releases includeFlorida Steel Corporation, 1.3 miles west of MRI, which released chromium, copper,aluminum oxide, manganese, lead, nickel, and zinc into the air. Reeves SoutheasternCorp. Galvanizing Division, 1.9 miles northwest of MRI, released zinc into the air. Reeves Southeastern Corp. Wire Division, 1.2 miles northeast of MRI, released leadand zinc into air and water. Universal Auto Radiator Manufacturing Company, 1.3 mileseast of MRI, released copper into the air.

Two sites on the National Priorities list are nearby. They are Stauffer ChemicalCompany and Helena Chemical Company. Stauffer is about 1.2 miles northwest ofMRI and Helena Chemical Company is 50 feet beyond Stauffer.


PATHWAY ANALYSIS

The amount of contact that people have with hazardous substances is essential toassessing the public health significance of a chemical. Chemical contaminants in theenvironment have the potential to harm human health, but only if people have contactwith those contaminants.

An exposure pathway is the process by which an individual comes into contact withcontaminants. The exposure pathway consists of five elements; 1) an original sourceof contamination like an industrial site, 2) an environmental media like air orgroundwater which moves contamination from the source to a place where people cancontact the contamination, 3) a place where people could contact the contaminated soilor groundwater like topsoil or a drinking water well, 4)a route of exposure like drinkingcontaminated water or touching contaminated soil, and 5) a group of people who canpotentially come in contact with the contamination like people living or working near thecontaminated site. A completed exposure pathway includes all of these elements.

The public health findings for communities surrounding the MRI site are based on areview of past and present environmental data to identify past, present, and futureexposure pathways. We identified exposure pathways that we determined are of publichealth significance in this assessment.

A. Potential Exposure Pathways

Groundwater
The most significant public health threat at the site is the future potential drinking orwashing with contaminated groundwater. The extent of off-site groundwatercontamination has not been determined. If contaminated groundwater moves offsite, itmay impact private wells in the area. Contaminants may eventually move into theFloridian Aquifer threatening municipal wells. Therefore, groundwater is a potentialfuture exposure pathway.

Soil
The on-site soil is contaminated, but several factors limit access and reduce thepotential of accidentally ingesting, inhaling or touching the soil. A fence surroundsmost of the site. Undeveloped land, such as wetlands and orchards, limit access onthe north and east while businesses in the industrial park, limit access on the south andwest of MRI. Presently access to soils is unlikely and exposure to on-site soils is anincomplete exposure pathway. However, if land use around the site changes in thefuture, the exposure pathway may also change. Therefore, on-site soil is a potentialfuture exposure pathway.

B. Eliminated Exposure Pathways

Sediment

Effluent (run off) from site operations contaminated sediment in the ditch on the easternsite boundary. Public access to the ditch is unlikely due to the undeveloped landsurrounding the site and lack of residential areas near the site. It is also unlikely thatcontaminated sediment would travel to a location where the public could be exposed. The ditch meanders 1.2 miles before it reaches Six Mile Creek, then another 2.9 milesbefore it reaches McKay Bay. McKay Bay is the closest body of water used for fishingand recreation. Since access to the sediments is unlikely, this exposure pathway was eliminated from further consideration.


PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

Groundwater consumption is currently a potential exposure pathway. The pathway willbe completed if the contaminated groundwater reaches private or municipal wells andpeople ingest it. We estimated an exposure dose of each contaminant a person mightreceive by drinking the contaminated groundwater (8). For non-cancerous compounds,we estimated the exposure dose that an elementary school child, weighing 24kilograms, would receive drinking about a half liter of contaminated groundwater perday, 250 days per year for 6 years. Children represent a sensitive subpopulation anddoses that are protective of children are most likely protective of adults. Forcarcinogenic compounds, we estimated an exposure dose that an adult, weighing 70kilograms, would receive over a lifetime of drinking 2 liters contaminated groundwaterper day.

To evaluate each contaminant of concern, we compared our estimate of exposure with health guidelines. These health guidelines provide perspective on the relativesignificance of human exposure to contaminants at the site. These values alone,however, cannot determine the potential health threat of a particular chemical. Ifexposure estimates were less than the health guideline, the contaminant was notevaluated further. If exposure estimates exceeded the health guideline or if there wasno health guideline, the estimated exposures were compared with doses in human oranimal studies. See the table below for comparison of exposure estimates from MRI tohealth guidelines.

To evaluate if the non-cancerous contaminants of concern are likely to pose a healththreat under site-specific exposure conditions, we compared estimate of exposuredoses to health guidelines such as ATSDR's Minimal Risk Level (MRL's) and EPA'sReference Doses (RfD's; see table below). RfD's and MRL's are an estimate of dailyexposure of a human being to a chemical that is likely to be without an appreciable riskof adverse health effects over a specified duration of exposure (7).

For possible cancer-causing chemicals, we compared estimates of exposure to EPA'scancer slope factors. We used a slope factor to estimate an upper-bound probability ofan individual developing cancer from a lifetime of exposure to a particular level of apotential carcinogen (7).



Comparison of Estimated Exposed Dose from Drinking Groundwater with Health Guidelines
Non- Cancer Cancer
Contaminant Estimated Daily Dose
mg/kg/d
Non-Cancer Health Guideline
(mg/kg/d)
Source Exceeds Non-cancer Health Guideline Estimated Lifetime Dose (mg/kg/d)-1 Carcinogenic Health Guideline
(mg/kg/d)-1
Source Exceeds Cancer Health Guideline
Aluminum 3.0 __ __ __ 0.3 __ __ __
Beryllium 0.0002 0.005 RfD NO 0.000015 4.3 Slope Factor NO
Chromium VI 0.02 0.005 RfD YES 0.001 __ __ __
Cyanide 0.8 0.05 MRL YES 0.07 __ __ __
Lead 0.2 __ __ __ 0.01 __ __ __
Manganese 0.011 0.14 RfD NO 0.0009 __ __ __
Nickel 0.5 0.02 RfD YES 0.04 __ __ __
Tin 0.4 0.6 RfD NO 0.03 __ __ __
Vanadium 0.2 0.003 MRL YES 0.001 __ __ __
Zinc 0.8 0.005 MRL YES 0.007 __ __ __
RfD: Reference Dose, EPA's non-cancer health guideline
MRL: Minimum Risk Level, ATSDR's non-cancer health guideline
Slope Factor: EPA's carcinogenic health guideline
__: Comparison values do not exist. See analysis below.
mg/kg/d: milligrams of contaminant per kilogram body weight per day

Aluminum
We do not anticipate adverse health effects from ingestion of aluminum incontaminated groundwater. The estimated average daily dose is 4.6 times lower than alevel causing adverse developmental effects in rats. The estimated lifetime averagedaily dose was 91 times lower than the lowest level without causing adverse effects in achronic exposure mouse study (9). EPA has not developed a slope factor for oralcarcinogenic effects.

Beryllium
We do not anticipate adverse health effects from ingestion of beryllium in contaminatedgroundwater. The estimated average daily dose was 25 times lower than the EPA'sRfD. The estimated lifetime average daily dose was almost 30,000 times lower thanEPA's cancer risk slope factor. See table for comparisons.

Chromium
We do not anticipate non-cancer health effects from ingestion of chromium incontaminated groundwater. The estimated average daily dose exceeded the EPA'sreference dose, but was three times lower than levels causing adverse health effects inshort term (acute) health studies in humans. The estimated lifetime average daily dosewas 570 times lower than levels causing adverse health effects in long-term humanstudies (10).

Because epidemiology studies of workers and animal studies showed that inhalation ofsome chromium IV compounds cause lung cancer, the EPA classified chromium as aknown carcinogen. We did not find any conclusive studies showing cancer from oralexposure to chromium VI in animals or humans. We are, therefore, unable todetermine the increased risk of cancer, if any, from chromium in the groundwater.

Cyanide
Ingestion of contaminated groundwater would expose adults and children to cyanide. The estimate of a child's potential cyanide exposure is above the ATSDR intermediateexposure MRL. No comparison values exist for chronic or carcinogenic effects ofcyanide. We could not find any studies suggesting cyanide can cause cancer inhumans or animals. EPA has determined that cyanide is not classifiable as to itshuman carcinogenicity.

The estimate of an elementary school child's potential cyanide exposure is one and ahalf times higher than the lowest human fatal dose reported. The estimate; however, is half the average human fatal dose. The estimate of a child's exposure is the samedose that caused labored respiration and hypoactivity in rats. The estimate of a child'sexposure is two times the level causing thyroid gland hypofunction and behavioralproblems in pigs. The estimate is higher than the level that caused rapid kidney cellgrowth and vomiting in pigs (11).

We estimate, in the future, that children would have an increased risk of laboredrespiration, hypoactivity, thyroid gland problems, behavioral problems, kidney problemsand vomiting from cyanide in the groundwater. However, there is currently little riskassociated with ingestion of the contaminated groundwater.

Lead
Drinking contaminated groundwater would expose adults and children to lead. Theestimate of a child's exposure to lead by drinking contaminated groundwater was eighttimes higher than a level that caused a decrease in erythrocyte ALA-D (blood enzymes)in a human study. This study detected increases in erythrocyte protoporphyrin infemales, but not males. Erythrocyte protoporphyrin is involved in the blood's oxygencarrying capacity. The estimate of a child's exposure to lead by drinking contaminatedgroundwater was three times higher than a level that decreased a monkey'sperformance in a learning discrimination test. The estimate of a child's exposure waseleven times higher than a level that caused rats to have irregular estrous(reproductive) cycles (12).

The estimate of an adult's chronic exposure to lead by drinking contaminatedgroundwater was lower than the lowest doses of lead in animal studies investigatingthe incidence of cancer. However, the high doses of lead given to these animals isdifficult to compare with the low levels that humans are exposed to. Therefore, theseestimates do not provide a sufficient basis for our assessment. We are unable todetermine the increased risk of cancer, if any, from lead in the groundwater.

We estimate, in the future, children would be at an increased risk of blood enzymeproblems, learning problems and reproductive cycle problems from lead in thegroundwater. There is currently little risk since no one is drinking the contaminatedgroundwater.

Manganese
We do not anticipate adverse health effects from ingestion of manganese in contaminated groundwater. The estimated average daily dose was lower than EPA'sRfD. The estimated lifetime average daily dose was 65 times lower than the levelcausing adverse effects in humans chronically exposed to manganese (13). EPA hasnot developed a slope factor for oral carcinogenic effects.

Nickel
We do not anticipate non-cancer health effects from ingestion of nickel in contaminated groundwater. The estimated lifetime average daily dose is 25 timeslower than the level causing adverse effects in dogs that are chronically exposed (14).

Because epidemiology studies of workers and animal studies showed inhalation of nickel compounds could cause lung cancer, the EPA classified nickel as a knownhuman carcinogen. Lifetime drinking water studies in rats and mice showed nickelacetate was noncarcinogenic. We are unable to determine the increased risk ofcancer, if any, from the nickel in groundwater.

Tin
We do not anticipate adverse health effects from ingestion of tin in contaminatedgroundwater. The estimated average daily dose was lower than EPA's RfD. Theestimated lifetime average daily dose is 2.3 times lower than levels causing adverseeffects following chronic exposure in rats and mice (15). EPA has not developed a slope factor for oral carcinogenic effects.

Vanadium
We do not anticipate adverse health effects from ingestion of vanadium incontaminated groundwater. The estimate of an elementary school child's potentialvanadium exposure dose is above the ATSDR intermediate exposure MRL. However,the estimated average daily dose was 38 times lower than the level that causedadverse effects in rats. The estimated lifetime average daily dose was 390 times lowerthan the levels that cause adverse effects in mice over a lifetime of exposure (16). EPAhas not developed a slope factor for oral carcinogenic effects.

Zinc
We do not anticipate adverse health effects from ingestion of zinc in contaminatedgroundwater. The estimate of an elementary school child's potential zinc exposure isabove the ATSDR intermediate exposure MRL. However, the estimated average dailydose is 6 times lower than the level causing adverse effects in humans. The estimatedlifetime average daily dose is 290 times lower than the levels causing adverse healtheffects in humans exposed over a lifetime (17). EPA has not developed a slope factorfor oral carcinogenic effects.

B. Health Outcome Data

Health outcome data for the community around this site was not evaluated. Since pastor current exposure is unlikely, there is little justification or community demand for anevaluation of health outcome data at this time. If future environmental investigationsfind complete exposure pathways, health outcome data review will be considered asappropriate.

C. Community Health Concerns

We were unable to identify any community health concerns.

D. Summary of Public Comment for the Draft Public Health Assessment

Stories regarding the draft assessment appeared in the Tampa Tribune on August 6, 1997. The Hillsborough County Health Department passed out copies of a fact sheetat local churches and libraries. The fact sheet summarized the draft assessment'sconclusions and recommendations and announced the report's availability. TheDepartment of Health solicited public comments through October 1, 1997. They did not receive any comments on the draft assessment.

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