PUBLIC HEALTH ASSESSMENT
ISLAND CHEMICAL CORPORATION/VIRGIN ISLAND CHEMICAL CORPORATION
CHRISTIANSTED, ST. CROIX, U.S. VIRGIN ISLANDS
To determine whether persons are exposed to contaminants from the Island Chemical/Virgin IslandChemical site, ATSDR has evaluated the environmental and human components, or pathways, thatlead to human exposure. This pathway analysis considers five elements: 1) a source ofcontamination; 2) an environmental medium in which contaminants may be present or through whichcontaminants may be transported; 3) a point of exposure; 4) a route of human exposure; and 5) anexposed population.
ATSDR classifies pathways as completed or potential. For a completed pathway to exist, all fiveelements must exist, and there must be evidence that human exposure to a contaminant has occurredin the past, is currently occurring, or will occur in the future. A potential pathway exists when at leastone of the five elements is missing, or is not clearly defined, but could exist (e.g., exposure to acontaminant could have occurred in the past, could currently be currently occurring, or could occur inthe future). A pathway is eliminated when at least one of the five elements is missing and will neverexist (e.g., there is no evidence that people have been, are, or will be exposed).
Completed and potential human exposure pathways for the Island Chemical/Virgin Island Chemicalsite are summarized in Tables 10 and 11, respectively. Estimates of the number of exposed personsfor completed exposure pathways and the number of potentially exposed persons for potentialexposure pathways are shown in Tables 12 and 13, respectively. The discussion that follows thesetables includes those exposure pathways considered important or relevant to the site. However,exposure pathways that have been eliminated are also discussed.
|PATHWAY NAME||EXPOSURE PATHWAY ELEMENTS||TIME|
|Source||Medium||Point of Exposure||Route of Exposure||Exposed Population|
|Municipal Water Supply||Chemical use, disposal, spillage, and/or leakage||Groundwater||Residences |
|Airport Water Supply||Chemical use, disposal, spillage, and/or leakage||Groundwater||Airport||Ingestion2 |
|Airport employees and visitors||Past|
2For airport employees and visitors
3For airport employees only
|PATHWAY NAME||EXPOSURE PATHWAY ELEMENTS||TIME|
|Source||Medium||Point of Exposure||Route of Exposure||Exposed Population|
|Private Well Water||Chemical use, disposal, spillage and/or leakage||Groundwater||Residences |
|Source Chemicals||Chemical use, disposal, spillage and/or leakage||Chemicals used/stored/manufactured at the plant; |
Air inside the lab or warehouse building
|Plant lab or warehouse||Skin contact; |
|Plant employees |
|Site Soil/ |
|Chemical use, disposal, spillage and/or leakage||Soil |
|Site areas with contaminated soil, sediment, and/or sludge, e.g., process pit, lab pit, and AST area (soil only)*||Incidental ingestion; Inhalation||Plant employees; |
Site workers involved in sampling and/or digging/drilling activities*
|River Gut Sediments||Chemical use, disposal, spillage and/or leakage||Sediment||River Gut||Ingestion |
|Persons accessing River Gut||Past |
|River Gut Surface Water||Chemical use, disposal, spillage and/or leakage||Surface Water||River Gut||Skin contact||Persons accessing River Gut while the plant was operating||Past|
|EXPOSED POPULATIONS||AFFECTED BY A COMPLETED EXPOSURE PATHWAY* FOR:|
|Location||EstimatedNumber||Chloroform||Other THMs (Bromoform,Bromodichloromethane, andChlorodibromomethane)||Inorganics (e.g., lead, mercury,sodium)|
|Persons using the municipalwater system||15,000||Municipal water supply||Unknown or No Exposure||Municipal Water Supply|
|Airport employees and visitors||>325||Airport water supply||Airport water supply||Airport Water Supply|
|POTENTIALLY EXPOSEDPOPULATIONS||AFFECTED BY A POTENTIAL EXPOSURE PATHWAY* FOR:|
(e.g. chloroform, Ethyl benzene, toluene)
(e.g., pyridine, phthalates)
(e.g. aldrin, chlordane, DDE)
(e.g., chromium, copper, lead, sodium)
|Private well users inthe site area||Unknown||Private well water**||Private well water**||Private well water**||Private well water**|
|Former plantemployees||Unknown||Source chemicals; |
|Source chemicals; |
|Source chemicals**; |
|Source chemicals**; |
|Unknown||Source chemicals; |
|Source chemicals; |
|Source chemicals**; |
|Source chemicals**; |
|Site trespassers||Unknown||Source chemicals; |
|Source chemicals; |
|Source chemicals**; |
|Source chemicals**; |
|Persons accessingRiver Gut||Unknown||River Gut sediments;River Gut surfacewater**||River Gut sediments;|
River Gut surface water**
|River Gut sediments||River Gut sediments|
** Sampling data are unavailable or insufficient to confirm the presence of this contaminant at the potential point of exposure.
Municipal Water Supply Pathway
Chloroform has been found in numerous environmental media at the site, including sludge, soils,sediments, groundwater, and in nearby VIWAPA municipal supply wells (Fairplains #6, #8, and#9). Chloroform was also known to have been used earlier at the site, as past investigations foundthe substance stored in drums and lab containers, as well as empty drums that had previouslycontained chloroform. It is therefore evident that past releases of chloroform resulted incontamination of site soils and groundwater. Moreover, the groundwater chloroform levels arehighest near the center of the site (in MW-2 near the former process pit), lower near the perimeter ofthe site (in wells P-1 and P-2), and generally lowest away from the site (in nearby VIWAPA andVIPA wells). This suggests that chloroform has migrated from the site and impacted nearby watersupply wells.
Persons using the municipal water system before the VIWAPA Fairplains wells were shut downwere likely exposed to chloroform in their drinking water. Exposure could have occurred bydrinking contaminants in the water (ingestion), by breathing contaminants evaporating from thewater during showering or other indoor water uses (inhalation), and by absorbing contaminantsthrough the skin during bathing, showering, etc.(dermal contact). It is estimated that up to 15,000people--the approximate number of persons served by the municipal water system--could havebeen exposed to low concentrations of chloroform from using municipal water. Because nosampling data are available for chloroform at the users' taps, the actual number of persons exposedand the actual exposure levels are not known. On one hand, because water from the wells wasmixed with water from the VIWAPA desalinization plants in Christiansted and from other non-contaminated VIWAPA municipal wells in the Fairplains water storage tank, chloroform levels atthe tap could have been much lower than those measured in the Fairplains water supply wells. (Note: Less than 30% of the water entering the water distribution system reportedly came from theFairplains wells). The chloroform levels at the tap could also have been lower than the levels foundin the municipal supply wells because of volatilization in the water distribution system. On the otherhand, because chloroform is a common by-product of water chlorination and water pumped from theFairplains storage tank was chlorinated prior to entering the water distribution system, it is possiblethat chloroform levels at the tap could have been similar to the levels found in the water supplywells.
Other VOCs present in groundwater beneath the site, such as ethylbenzene, toluene, and xylenes,have not been detected, to date, in any water supply wells near the site. However, thesecontaminants have only recently appeared in site groundwater, and no sampling data for themunicipal supply wells have been collected in the past several years. It is possible, therefore, thatVOCs other than chloroform may eventually migrate from the site and into nearby public watersupply wells.
Persons using the municipal water system could also have been exposed to inorganics (such ascalcium, lead, magnesium, manganese, mercury, and sodium) detected in the VIWAPA Fairplainswells. Note: These contaminants could be naturally occurring and not be related to contamination atthe Island Chemical/Virgin Island Chemical site. Human exposure to inorganics in the Fairplainswells was likely insignificant because of the levels of contaminants in the Fairplains wells, and thelarge amount of dilution provided by mixing water from the Fairplains wells with water from otherVIWAPA well fields and the VIWAPA desalination plant.
Airport Water Supply Pathway
Chloroform has been detected in the two VIPA airport supply wells, which are located less than aquarter mile southwest of the Island Chemical/Virgin Island Chemical site. As previously discussed,chloroform released into groundwater at the site has likely migrated into off-site water supply wellsincluding the two airport wells.
Until recently, water from the two airport wells was pumped into a storage tank near the airport andoccasionally chlorinated. Water from the storage tank was distributed to the airport terminal andother operations at the airport for various uses, including drinking fountains and restrooms. Samplescollected at various points in the airport's water distribution system between May 1992 and October1995 indicated chloroform and three other trihalomethanes (THMs)--bromoform,bromodichloromethane, and chlorodibromomethane--in the airport's water supply. Bromoform,bromodichloromethane, and chlorodibromomethane in the water distribution system could havebeen by-products of chlorination, rather than actual site-related contaminants.
Airport visitors were likely exposed to THMs in the airport's water supply through ingestion (i.e.,drinking), while airport employees were likely exposed through ingestion and possibly inhalationand skin contact (during showering in the employees' shower rooms.) About 325 airport employeesare estimated to have been exposed to low levels of THMs in the airport water supply; however, thenumber of airport visitors exposed is unknown.
Airport visitors and employees could have also been exposed to inorganic contaminants (such asaluminum, iron, lead, sodium, and vanadium) in the airport's drinking water. These contaminantswere detected in the airport's two water supply wells; however, they could have been naturallyoccurring and, therefore, unrelated to contamination at the site.
The Alexander Hamilton Airport was recently connected to the VIWAPA municipal water system tosupply all its water needs. At that time, the two airport wells were shut down. VIPA officials haveindicated that the two wells will not be used in the future, except in cases of emergency.
Private Well Water Pathway
Numerous private wells have been reported in the site area for uses such as drinking water,irrigation, and commercial/industrial operations; however, information regarding specific wells andtheir locations is limited. Two wells at the concrete plant about 150 feet east of the site and twowells at the asphalt plant about 700 feet northwest of the site are the private wells closest to the site. These four wells, which are located across River Gut from the site, are used forindustrial/commercial purposes only--not for potable water supply. The closest private wells usedfor drinking water are not known for certain, but could be the wells at the Golden Grove TrailerPark located approximately three-quarters of a mile northwest of the site.
Although no private wells in the site area are likely to have been impacted by groundwatercontamination from the site, no sampling data are available at the present time for confirmation. Itis possible that private wells in the site area could be affected in the future, as chloroform and otherVOCs (such as ethylbenzene and xylene) continue to migrate away from the site. People using suchwells for drinking water and other household uses could be exposed to VOCs from the site throughingestion, inhalation, and dermal contact (as discussed previously under the Municipal WaterSupply Pathway).
Source Chemicals Pathway
Three main groups of people were potentially exposed to chemicals used, manufactured, or stored atthe Island Chemical/Virgin Island Chemical plant: 1) former plant employees, 2) site investigators,and 3) site trespassers. Former plant employees, such as lab or warehouse workers, who handled orworked around raw materials, intermediate products, or finished products could have been exposedto contaminants through inhalation or skin contact. Site investigators involved in environmentalinspections, sampling activities, or removal actions at the site were potentially exposed to chemicalsor wastes stored or disposed of on the site property. For instance, during site removal activities inJanuary 1990, environmental technicians were likely exposed to benzyl chloride and triethylaminewhile sampling drums in the warehouse. According to site documents, the technicians experiencedskin irritation when benzyl chloride broke through their protective clothing and were later evacuatedfrom the warehouse when triethylamine vapors reached unsafe levels. Site trespassers could havebeen exposed to chemicals or wastes stored onsite after the plant shutdown. For example, in Octoberor November 1990, trespassers entered the warehouse building and overturned a number of drumscontaining powders (such as salicylic acid), and corrosive liquids (such as acetic acid and sodiumhydroxide). The trespassers were probably exposed to some of these chemicals through skin contactand inhalation when the contents of the drums were dumped on the warehouse floor.
Site Soil/Sediment/Sludge Pathway
In the past, a number of organic contaminants (including benzophenone, chloroform, pyridine,quinidine gluconate, quinidine sulfate, and toluene) were found in site soils, sediments, and/orsludges. Most of the contaminants were limited, however, to specific areas of the site, such as theprocess pit area, the lab pit/loading dock area, the AST area, and the central storm drain. Over theyears, the contaminated materials in these areas were either removed or remediated. Although somepersons, such as plant employees, site investigators, or site trespassers could have been exposed tocontaminants in site soils, sediments, and/or sludges in the past, the potential for current exposure isminimal.
Current soil contamination at the site is generally limited to an area near Tanks #8 and #9 in theAST area. This contamination, which reportedly resulted from spillage and/or leakage of volatilechemicals and possibly diesel fuel from one or more of the ASTs, is found at a depth of more than10 feet below ground. Human exposure to contaminated soil at such a depth is unlikely except forpersons involved in drilling or excavation activities, such as site investigators or remedial workers. These persons might experience short-term exposure to soil contaminants through incidentalingestion of contaminated soil or through inhalation of contaminants volatilizing from the soil. Suchexposures, however, would likely be minimal since site workers are likely to use appropriateprotective measures when conducting extensive soil-disturbing activities in areas wherecontaminated soil is present.
River Gut Sediment Pathway
Low levels of organic contaminants, such as butyl benzyl phthalate and di-n-octylphthalate, andelevated levels of inorganics, such as beryllium and zinc, have been detected in the past in thesediments of the River Gut stream channel. These contaminants were found primarily where processwater and contaminated stormwater from the central storm drain discharged to the gut. Persons whoaccess the gut, such as those observed standing with their horses in the gut downstream of the site,could be exposed to contaminants in the sediments through incidental ingestion and skin contact. However, due to the low levels of contaminants detected in the gut sediments and the difficulty oftraversing the heavily vegetated gut stream channel next to the site, significant exposure to site-related contaminants in gut sediments is unlikely.
River Gut Surface Water Pathway
In the late 1970s and early 1980s, while the plant was in operation, process wastewater wasdischarged to River Gut from the lab pit and from the process pit (via the central storm drain). Based on historical sampling data from the lab pit, process pit, and storm drain lines, thesedischarges contained numerous organic contaminants, such as chloroform, methylene chloride,phenol, toluene and xylenes, and reportedly had a very high pH (13). As such, children who swamor played in the gut downstream of the plant (13) may have been exposed to contaminants in thegut's surface water through dermal absorption. In addition, due to the high pH of the plant'sdischarges, these children may also have experienced skin and/or eye irritation from swimming orwading in the gut. Human exposure to contaminated surface water in the gut likely ceased after the plant shut-down in late 1982 and stopped discharging process wastewater to the gut.
The contaminants of concern (Table 14) released into the environment at the Island Chemical/VirginIsland Chemical site have the potential to cause adverse health effects. However, for adverse healtheffects to occur the pathway for exposure must be completed. A release does not always result inexposure. Rather, a person can only be exposed to a contaminant by coming in contact with thecontaminant. Health effects resulting from the interaction of an individual with a hazardoussubstance in the environment depend on several factors. One is the route of exposure: that is,whether the chemical is breathed, consumed with food, soil, or water, or whether it contacts the skin. Another factor is the dose to which a person is exposed, and the amount of the exposure doseactually absorbed. Mechanisms by which chemicals are altered in the environment or inside thebody, as well as the combination (types) of chemicals are also important. Once exposure occurs,characteristics such as age, sex, nutritional status, genetics, life style, and health status of theexposed individual influence how the contaminants are absorbed, distributed, metabolized, andexcreted. Together, those factors and characteristics determine the health effects that can occur as aresult of exposure to a contaminant. Much variation in those mechanisms exists among individuals. For example, all children mouth or ingest non-food items to some extent. The degree of picabehavior varies widely in the population, and is influenced by nutritional status and the quality ofcare and supervision (18). Groups that are at increased risk for pica behavior are children 1 to 3years old, children from families of low socioeconomic status, and children with neurologicdisorders (e.g., brain damage, epilepsy, and metal retardation).
Health guidelines provide a basis for comparing estimated exposures with concentrations ofcontaminants in different environmental media (soil, air, water, and food) to which people could beexposed.
Noncancer Health Effects
ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found athazardous waste sites. The MRL is an estimate of daily exposure to a contaminant below whichnoncancer, adverse health effects are unlikely to occur. MRLs are developed for different routes ofexposure (e.g., inhalation and ingestion), and for length of exposure, such as acute (less than 14days), intermediate (15-364 days), and chronic (365 days or greater). Oral MRLs are expressed inunits of milligrams of contaminant, per kilogram of body weight, per day (mg/kg/day). BecauseATSDR has no methodology to determine amounts of chemicals absorbed through the skin, theAgency has not developed MRLs for dermal exposure. The method for deriving MRLs does notinclude information about cancer, therefore, an MRL does not imply anything about the presence,absence, or level of cancer risk. If an ATSDR MRL is not available as a health value, then EPA'sReference Dose (RfD) is used. The RfD is an estimate of daily human exposure to a contaminantfor a lifetime below which (non-cancer) health effects are unlikely to occur (18).
Cancer Health Effects
The Environmental Protection Agency (EPA) classifies chemicals as Class A, Class B, Class C,Class D, or Class E. This classification defines a specific chemical's ability to cause cancer inhumans and animals. According to EPA, Class A chemicals are known human carcinogens, andClass B chemicals are probable human carcinogens. Class B is further subdivided into two groups:Group B1 consists of chemicals for which there is limited evidence of carcinogenicity fromepidemiologic studies in humans; and Group B2 consists of chemicals for which there is sufficientevidence of carcinogenicity in animals, but inadequate evidence or no data available fromepidemiologic studies in humans. Group C chemicals are possible human carcinogens. Group Dchemicals are not classifiable as to human carcinogenicity, and Group E chemicals are those forwhich there is evidence that they are not carcinogenic to humans. For carcinogenic substances, EPAhas established the Cancer Slope Factor (CSF) as a guideline. The CSF is used to determine thenumber of excess cancers resulting from exposure to a contaminant. In its Annual Report onCarcinogens, the National Toxicology Program (NTP) classifies a chemical as a "known humancarcinogen" based on sufficient human data. Its classification of a chemical as being "reasonablyanticipated to be a carcinogen" (RAC) is based on limited human or sufficient animal data. ATSDRconsiders the above physical and biological characteristics when developing health guidelines (18).
Exposure Dose Estimation
To link the site's human exposure potential with health effects that can occur under site-specificconditions, ATSDR estimates human exposure to the site contaminant from ingestion and/orinhalation of different environmental medium (18). The following relationship is used to determinethe estimated exposure to the site contaminant:
|where:||ED = exposure dose (mg/kg/day)||C = contaminant concentration|
|IR = intake rate||EF = exposure factor|
|BW = body weight|
Standard body weights for adults, young children, and toddlers are 70 kg, 16 kg and 10 kg, respectively. The maximum contaminant concentration detected at a site for a specific medium is used to determine the estimated exposure, and use of the maximum concentration will result in the most protective evaluation for human health. The ingestion rates used are 1 liter of water per day for children and 2 liters of water per day for adults. Some exposures are intermittent or irregularly timed, and for those exposures, an exposure factor (EF) is calculated which averages the dose over the exposed period. When unknown, the biological absorption from the water is assumed to be 100%.
Development of Risk Estimates
For noncancer health risks, the contaminant intake was estimated using exposure assumptions forthe site conditions. This dose was then compared to a risk reference dose (estimated daily intake ofa chemical that is likely to be without an appreciable risk of health effects) developed by ATSDR orEPA.
Noncancer effects, unlike carcinogenic effects, are believed to have a threshold (i.e., a dose belowwhich adverse effects will not occur). As a result, the current practice is to identify, usually fromanimal toxicology experiments, a no-observed-adverse-effect-level (NOAEL). This is theexperimental exposure level in animals at which no adverse toxic effect is observed. The NOAEL isthen divided by an uncertainty factor (UF) to yield a risk reference dose. The UF is a number thatreflects the degree of uncertainty that exists when experimental animal data are extrapolated to thegeneral human population. The magnitude of the UF takes into consideration various factors, suchas sensitive sub-populations (for example, children, pregnant women, and the elderly), extrapolationfrom animals to humans, and the incompleteness of available data. Risk reference doses are selectedto be much lower than dosages that do not cause adverse health effects in laboratory animals. Thus,exposure doses at or below the risk reference dose are not expected to cause adverse health effects inhumans.
The measure used to describe the potential for noncancer health effects to occur in an individual isexpressed as a ratio of estimated contaminant intake to the risk reference dose. If exposure to thecontaminant exceeds the risk reference dose, there is concern for potential noncancer health effects. As a rule, the greater the ratio of the estimated contaminant intake to the risk reference dose, thegreater the level of concern. A ratio equal to or less than one is generally considered an insignificant(minimal) increase in risk.
Increased cancer risks were estimated by using site-specific information on exposure levels for thecontaminant of concern and interpreting them using cancer potency estimates derived by EPA, forthat contaminant. An increased, excess-lifetime, cancer risk is not a specific estimate of expectedcancers. Rather, it is an estimate of the increase in the probability that a person could developcancer sometime in his or her lifetime following exposure to that contaminant.
Knowledge of cancer mechanisms is currently insufficient to decide if a level of exposure to acancer-causing agent exists below which there is no risk of getting cancer--i.e., a threshold level. Every exposure, no matter how low, to a cancer-causing compound is assumed to be associated withsome increased risk. As the dose of a carcinogen decreases, the chance of developing cancerdecreases, but each exposure is accompanied by some increased risk.
A general consensus has not been reached within the scientific or regulatory communities on anacceptable level of estimated excess cancer risk. Because of the uncertainties in our scientificknowledge about the mechanism of cancer, some have recommended the use of the relativelyconservative, excess-lifetime, cancer risk level of one in one million. Others feel that lower or higherrisks can be acceptable, depending on scientific, economic and social factors. An increased lifetimecancer risk of one in one million or less is generally considered an insignificant increase in cancerrisk.
Sources of Health Guideline Information
ATSDR has prepared toxicological profiles for many substances found at hazardous waste sites. Those documents present data and interpret information on the substances. Health guidelines, suchas ATSDR's MRL and EPA's RfD and CSF are included in the toxicological profiles. Those healthguidelines are used by ATSDR health professionals in determining the potential for developingadverse noncarcinogenic health effects and/or cancer from exposure to a hazardous substance. Preparers of this public health assessment have reviewed the profiles for the contaminants of concernat the Island Chemical/Virgin Island Chemical site.
Development of Estimated Risks at the Island Chemical/Virgin Island Chemical Site
ATSDR has identified two off-site, completed, human-exposure pathways associated with the IslandChemical/Virgin Island Chemical site. The first completed exposure pathway involves airportemployees and visitors who were likely exposed in the past to low levels of contaminants (Table 14),including THMs and inorganics (i.e., aluminum, iron, lead, sodium, and vanadium) in the airportwater supply wells via ingestion and/or dermal contact. Because the point of exposure was at taps orshowers located in the airport, it is believed that these exposures would have been intermittent. Because the nature of the contaminants and the process of delivery of the drinking water, it isunlikely that exposed persons would have been subjected to any contaminant at the maximumconcentration detected during sampling events. It is estimated that about 325 airport employeescould have been exposed to the low level contaminants in the airport water supply; however, thenumber of airport visitors exposed is unknown. The second completed exposure pathway involvesusers of the municipal water supply who were likely exposed in the past to low levels of chloroform,lead, manganese, mercury, and sodium (Table 14) from the VIWAPA Fairplains wells. Exposure tothese chemicals would have occurred at any location that utilizes the municipal water supply as asource of drinking water. It is estimated that up to 15,000 people--the approximate number ofpersons served by the municipal water system--could have been exposed to low level contaminantsin the municipal water supply.
Discussion of Contaminants of Concern
Bromoform is a clear, heavy liquid that does not burn and is relatively stable in water. In the past ithas been used by industry to dissolve dirt and grease and to make other chemicals, such as fireextinguisher fluid. Earlier this century it was used as a medicine to help children with whoopingcough fall asleep. Currently, it is produced in small amounts for use in laboratories and in electronicand geological testing.
Bromoform is inadvertently generated during water chlorination when chlorine reacts withendogenous organic materials such as humic acid. Usually the level of bromoform in chlorinateddrinking water is between 1 and 10 micrograms per liter (µg/l). Bromoform has also been detectedin chlorinated swimming pools. In these situations bromoform can enter the body via ingestion,inhalation, and possibly via dermal absorption (although this has not been studied). Most of thebromoform is eliminated from the body via respiration, with 50% to 90% being eliminated withineight hours.
Bromoform was detected at a maximum concentration of 121 µg/l in water samples taken from the airport supply wells. The calculated exposure doses are more than 100,000 times lower than the short-term exposure lowest-observed-adverse-effect-level (LOAEL) for humans (sedation) and the long-term NOAEL for animals (ulcer). No studies were found regarding health effects in humans following inhalation or dermal exposure to bromoform. At the reported concentrations, ATSDR does not expect any adverse, noncancer, health effects to occur in people exposed to bromoform in the airport water supply.
The EPA classifies bromoform as a Class B2 probable human carcinogen, based upon animalstudies. The estimated exposure dose is more than 100,000 times lower than the cancer effect level(CEL) for animals. No increased risk for developing carcinogenic effects is expected in peopleexposed to the water at the airport.
Studies in animals suggest that humans exposed to alcohols, ketones, or other drugs that influencehalomethane metabolism might be more susceptible to the toxic effects of bromoform. Becausethese organs are adversely affected by exposure to bromoform, persons with existing renal or hepaticdisease might also be more susceptible to the toxic effects.
Bromodichloromethane (BDCM) is a colorless, nonflammable, heavy liquid that evaporatesquickly. It is usually found in the environment, dissolved in water or evaporated in air. BDCM isformed as a by-product when chlorine is added to drinking water. Small amounts of BDCM areproduced for use in laboratories or in making other chemicals.
BDCM was detected in the airport water supply wells at a maximum concentration of 2 µg/l. Surveys of BDCM levels in chlorinated public drinking water systems across the United States have revealed that BDCM is present in most systems at concentrations averaging around 1 to 20 µg/l. The health effects resulting from short-term or long-term exposure via ingestion of water or inhalation of air containing specific levels of BDCM are not known. However, noncancer health effects are not expected to occur in people exposed to BDCM at the reported level.
BDCM is classified as a Class B2 probable human carcinogen, based upon animal data. However, atthe reported level, ATSDR expects no increased risk of developing cancer from exposure to BDCM.
No studies were found regarding human populations especially susceptible to BDCM. However,since BDCM is known to cause liver injury in animals, it is possible that people with preexistingliver disease may be more susceptible to the hepatotoxic effects of BDCM. Likewise, people withpreexisting kidney disease may also be susceptible to BDCM. By analogy with carbontetrachloride, persons who are heavy drinkers and/or take certain drugs that affect the liver may alsobe particularly susceptible to the effects of BDCM.
Chloroform (or trichloromethane) is a colorless liquid with a pleasant, nonirritating odor. It has aslight, sweet taste. Nearly all chloroform made in the United States is used to produce otherchemicals. Small amounts of chloroform are formed as an unwanted byproduct when chlorine isadded to water to destroy bacteria.
Chloroform can easily enter the body through the skin. If the water is hot enough for the chloroformto evaporate, the chemical can also be inhaled during showering or bathing. Inhaled and ingested,chloroform quickly enters the bloodstream from the lungs and intestines. Once in the bloodstream itcan be transported to other body tissues. Chloroform has an affinity for body fat. Some of thechemical is excreted in expired air, unchanged, and some is broken-down into by-products that, onceinside susceptible cells, can cause harmful effects. Some of these breakdown products are releasedfrom the body in expired air, and a small portion leave the body via urination and excretion.
Chloroform has been detected in water from outdoor pools, indoor pools and spas at concentrations ranging between 4 and 402, 3 and 580, and <0.1 and 530 µg/l, respectively. In another study, water from whirlpool spas treated with chlorine disinfectant contained chloroform concentrations ranging from 15 to 674 µg/l. Chloroform was found in airport water supply wells and municipal wells at a maximum concentration of 11.5 and 75 µg/l, respectively. The chronic oral MRL for chloroform is 0.01 mg/kg/day. The estimated daily exposure for persons possibly consuming the water is below the chronic oral MRL; therefore, exposure to the contaminant, at the reported concentrations, is not expected to cause adverse non-cancer health effects.
No studies were found regarding the carcinogenic effects in humans and animals following inhalation or dermal exposure to chloroform. Epidemiologic studies support a weak but significant association between risks of colon, bladder and rectal cancer and water chlorination constituents. Although human data suggest a possible increased risk of cancer at these three sites from exposure to chloroform in chlorinated drinking water, because chloroform is the predominant trihalomethane in drinking water, the data are too weak to support a conclusion about the carcinogenic potential. However, EPA has classified the substance as a probable human carcinogen by inhalation and ingestion. Both the NTP and the International Agency for Research on Cancer (IARC) have determined that this substance is anticipated to be a carcinogen. Based on the above worse-case scenario, there would be no increased risk of cancer from chronic exposure to chloroform at the maximum detected level of 75 µg/l in the contaminated water.
Individuals with liver or kidney impairment are more susceptible to chloroform toxicity becausechloroform is metabolized mainly by these organs. Drinking water containing higher thanacceptable levels of chloroform for extended periods of time can increase the risk for toxic side-effects. Chloroform's toxic effects upon the liver can also be increased by exhaustion and starvation. Studies on mice indicate that males can be more susceptible to the toxic effects of chloroform thanfemales. This was associated with the level of testosterone in the animals, but it is not presentlyknown if the same applies to humans.
Chlorodibromomethane (CDBM) is heavy, colorless, nonflammable liquid trihalomethane with a sweetish odor. In the past it was used to make other chemicals, such as fire extinguisher fluids, spray can propellents, and pesticides. It is currently produced only in small amounts for use in laboratories. CDBM is rarely measurable in non-chlorinated waters; however, it is frequently found in chlorinated drinking water. The levels of CDBM in finished drinking water has been investigated in several studies and, except for a few cases, the concentrations were less than 100 µg/l, with the average concentrations generally less than 10 µg/l.
CDBM was found in water samples taken from the airport water supply wells at a maximumconcentration of 8 µg/l. The estimated exposure doses were more than 1,000,000 lower than theshort-term and long-term LOAEL for less serious effects (minimal histological changes and fattychanges, respectively) in animals. No studies were found regarding health effects in humansfollowing exposure to CDBM via inhalation, ingestion, or dermal absorption. ATSDR does notexpect any adverse noncancer health effects in people exposed to CDBM at the levels reported.
CDBM is classified by EPA as a Class B2 probable human carcinogen, based upon animal studydata. However, ATSDR expects no increased risk of developing cancer from exposure to CDBM atthe reported levels.
Studies in animals suggests that humans exposed to alcohols, ketones, or other drugs that influencehalomethane metabolism, might be more susceptible to the toxic effects of chlorodibromomethane. Persons with existing kidney or liver disease might also be more susceptible, since these organs areadversely affected by exposure to chlorodibromomethane.
Lead (Pb) is a naturally occurring bluish-grey metal. It has no special taste or smell and can befound in all parts of the environment. Most of the Pb comes from human activities, such as mining,manufacturing, and burning fossil fuels. Pb's most important use is in the production of batteries. Ithas many other uses, and can also be found in ammunition, metal products (pipes and solder),roofing, and devises to shield x-rays. Because of health concerns, Pb from gasoline, pipe solder,caulking, paints, and ceramics has been drastically reduced in recent years.
Foods such as fruits, grains, meat, seafood, soft drinks, vegetables and wine may contain Pb.Cigarettes also contain small amounts of lead. In addition, more than 99% of all drinking watercontains less than 0.005 milligrams per liter (mg/l) Pb. However, the amount of Pb taken into thebody through drinking water can be higher in communities with acidic water supplies. Childrenresiding in older dwellings may be exposed to Pb by eating lead-based paint chips from peelingsurfaces. This is particularly a problem in lower income communities. For occupationally exposedindividuals, the usual route of exposure is through inhalation of Pb particles.
Pb was detected in water samples from the airport supply wells (0.018 mg/l) and the municipal wells(0.0042 mg/l). ATSDR has no MRL and EPA has no RfD for Pb, however, the estimated exposuredoses for each target population is below the LOAEL for neurological effects in monkeys (0.05mg/kg/day). Ingestion of Pb at very high levels, over time, can result in neurological impairmentsuch as learning disabilities, especially in children. ATSDR believes that most of the exposureswould have occurred on an intermittent basis, to low levels of contaminants. Currently ATSDRdoes not have any biological data on people who could have ingested the contaminated water, andsuch information would be required to make an accurate determination of possible health effects.
Pb is classified by EPA as a Class B2 probable human carcinogen, based on animal studies. Whilethere is inadequate evidence to determine Pb's carcinogenicity in humans, the estimated exposuredose is more than 100,000 times lower than the CEL in animals.
Pb exposure is particularly hazardous for unborn children and young children because they are more sensitive to it during their development. The American Academy of Pediatrics considers Pb a significant hazard to the health of children in the United States. The blood lead levels defining lead poisoning have been declining, and the current consensus level of concern for children is 10 to 14 micrograms per deciliter (µg/dL). Effects on stature have been reported to begin at levels as low as 4 µg/dL, which is the present limit for accurate blood lead measurement. Taken together, effects occur over a wide range of blood lead concentrations, with no indications of a threshold. No safe level has yet been found for children, and even in adults, effects are being discovered at lower and lower levels as more sensitive analyses and measurements are developed.
Manganese is a silver-colored metal in its pure form and is found as a natural constituent in manytypes of rock. The metal form does not occur naturally in the environment, but rather incombination with other chemicals such as chlorine, oxygen, and sulfur. The metal manganese ismixed with iron to make steel. Some manganese compounds are used in the production of batteries,as an ingredient in some ceramics, pesticides, and fertilizers, and in dietary supplements.
The level of manganese in drinking water is usually about 0.004 mg/l, whereas in soils the levelusually ranges from 40 to 900 mg/kg. For nearly all people, food is the main source of manganese,and usual daily intakes range from about 2,000 to 9,000 micrograms per day. The exact amountconsumed depends upon the diet.
Manganese was found in water samples taken from municipal wells at concentrations ranging from17.7 to 400 micrograms per liter. The estimated exposure dose for children drinking the water on adaily basis is slightly lower than the LOAEL for less serious effects in humans (0.059 mg/kg/day). Dermal absorption of manganese does not appear to be toxicologically significant, and no studieswere found regarding carcinogenic effects in humans following exposure to manganese viaingestion, inhalation, or dermal absorption. ATSDR does not expect any adverse non-carcinogenicor carcinogenic health effects in people exposed to manganese at the levels detected in the municipalwell water.
Neonates tend to retain a higher amount of manganese in their bodies than adults, and very highlevels of retained manganese can lead to neurotoxicity. Other susceptible populations include theelderly, people with liver disease, and people with respiratory disease. Smokers are more susceptibleto development of respiratory symptoms (wheezing, bronchitis) from inhalation of manganese duststhan non-smokers.
Mercury is a naturally occurring metal that has several forms. The metallic mercury is a shiny,silver-white, odorless liquid. If heated, it is a colorless, odorless gas. Mercury combines with otherelements to form salts, most of which are white powders or crystals. Mercury combined with carbonforms organic mercury. The most common organic mercury is methyl mercury.
Metallic mercury is used to produce chlorine gas and caustic soda (lye) and also in thermometers, dental fillings, and batteries. Mercury salts are used in skin-lightening creams and in antiseptic creams and ointments. Since mercury occurs naturally in the environment it may be present in surface waters even when man-made sources of mercury are not present. The concentrations of mercury in rainwater and fresh snow are generally below 0.2 µg/l, and drinking water is generally assumed to contain less than 0.025 µg/l of mercury.
Mercury was detected in municipal wells and airport supply wells at maximum concentrations of 3.3 and 1.2 µg/l, respectively. The estimated exposure doses are more than 100,000 times lower than the LOAEL for less serious effects in humans (nausea, vomiting, etc.). Therefore, ATSDR does not expect any adverse noncancer effects to occur in people who drank the contaminated waters at the levels reported.
Because of lack of data from studies on people and laboratory animals, The Department of Healthand Human Services, the Environmental Protection Agency, and the International Agency forResearch on Cancer, have not classified mercury as to its human carcinogenicity. No studies werefound regarding cancer in humans following oral or dermal exposure to inorganic mercury, and nostudies were located regarding cancer in animals following inhalation exposure to metallic mercury.
Sodium (chloride) (25)
Sodium chloride is generally in the form of colorless, transparent crystals to a white, crystallinepowder. It is often referred to as "salt". Sodium chloride, at various concentrations, has a widevariety of uses in day-to-day life. In industry it is often used to produce chlorine, caustic soda, andsoda ash, mainly in the form of brine. Sodium chloride is rapidly attacked by bromine triflouride.
Sodium chloride is required by the human body to maintain proper electrolyte balance. Sodium,presumably in the form of sodium chloride, was detected in samples taken from the airport supplywells and the municipal wells at maximum concentrations of 572 mg/l and 590 mg/l, respectively.
Young children are very susceptible to the toxic effects of sodium chloride. Accidental substitutionof sodium chloride for lactose in infants formulas have led to accidental fatal poisonings. Sodiumchloride is filtered by the kidneys, therefore, people with kidney disease are susceptible to the effectsof sodium chloride.
Vanadium is a naturally occurring white to grey metal that is often found in the crystalline form. Itdoes not occur in the environment in its pure state, which is virtually odorless, but rather combinedwith other elements to form chloride, oxygen, sodium, or sulfur compounds. It is not well known which forms of vanadium are more likely to be found at waste sites.
|Contaminant||Pathway Medium||Health Guideline (mg/kg/day)||Cancer Class|
|Value||Source||Exceeded by Estimated Exposure Dose|
|Bromoform||Airport Supply Wells||0.2||MRL||NO||B2|
|Bromodichloromethane||Airport Supply Wells||0.02||MRL||NO||B2|
|Chloroform||Airport Supply Wells |
|Chlorodibromomethane||Airport Supply Wells||0.03||MRL||NO||C|
|Lead||Airport Supply Wells |
|Mercury||Airport Supply Wells |
|Sodium||Airport Supply Wells |
|Vanadium||Airport Supply Wells||0||RfD|
|Unknown = Health guideline not available |
MRL = ATSDR's Minimal Risk Level
None = Health guideline not available
RfD = EPA's Reference Dose
Most people are exposed to low concentrations of vanadium daily via food, drinking water, and air. Aperson may take in as much as 10-20 micrograms per day in food.
Vanadium has been found in groundwater and at hazardous waste sites throughout the United States. In thepast, vanadium was found in the airport water supply wells at a concentration of 50.3 µg/l. Drinking wateris not considered to be an important source for vanadium exposure as vanadium does not dissolve well inwater, but it can be carried in the water much the same way that sand is carried. Vanadium that has beeningested is unlikely to enter the bloodstream; it will most likely be excreted in the feces. It is also unlikelyto enter the body via dermal exposure. The estimated exposure doses are less than the intermediate MRL of0.003 mg/kg/day; therefore no illnesses are expected for people ingesting the water on an intermittent basisat the levels reported.
Toxicological Evaluation Summary
The estimated exposure dose for children consuming municipal water containing manganese at themaximum concentration reported was greater than EPA's reference dose. It was slightly less than theLOAEL for less serious effects in humans; therefore, ATSDR does not expect any adverse noncancer healtheffects to occur in the exposed children. Because of the lack of biological data, ATSDR could not determineif adverse health effects were likely to occur or have occurred as a result of exposure to lead in the watersupplies. Adverse noncancer health effects are not expected from exposure, via ingestion, to the othercontaminants evaluated in the Public Health Implications section of this document. However, because ofthe lack of air data, inhalation exposures could not be thoroughly evaluated at this time.
Carcinogenic health effects are not expected to occur as a result of exposure to bromoform,bromodichloromethane, chloroform, chlorodibromomethane, manganese, and vanadium. It is not known iflead, sodium, or mercury causes cancer in humans.
ATSDR conducts a review of health outcome data when the toxicologic evaluation indicates the likelihoodof adverse health outcomes or when the community near the site has health concerns. The evaluation ofhealth outcome data can give a general picture of the health of a community, or confirm the presence ofexcess disease or illness in a community. However, elevated rates of a particular disease might notnecessarily be caused by hazardous substances in the environment. Other factors, such as personal habits,socioeconomic status, and occupation, can also influence the development of disease. In contrast, even ifelevated rates of disease are not found, a contaminant can still have caused illness or disease.
The population surrounding the site is relatively small and transient. Health outcome data were notevaluated at this site because no previous health studies on the population around the site were identifiedduring the gathering of data and information for this public health assessment. In addition, the VirginIslands do not have a centralized cancer registry that could be used to determine if the occurrence of cancer,if any, near the Island Chemical/Virgin Island Chemical site is more than would be expected.
ATSDR has conducted two visits to the Island Chemical/Virgin Island Chemical NPL site. No community health concerns were identified during the process of gathering data and information for this public health assessment.
- ATSDR has classified the Island Chemical/Virgin Island Chemical site a no apparent publichealth hazard because available environmental sampling data do not indicate that people have beenexposed to site contamination at levels that would be expected to cause adverse health effects. Nevertheless, ATSDR believes the site's numerous physical hazards, including miscellaneous debris(e.g., old pipes, pieces of metal, old plant equipment, junk cars, old tires, nails, old lockers, old labequipment); dilapidated and deteriorating buildings and storage tanks; and unsecured outside stairways could pose a minor safety threat to site trespassers.
- ATSDR has identified two completed human exposure pathways associated with contaminationfrom the site: 1) users of the municipal water supply who were likely exposed to low levels ofcontaminants, such chloroform, lead, and mercury, in their residential drinking water, and 2)workers and visitors at the Alexander Hamilton Airport who were likely exposed to low level ofcontaminants, including bromoform, bromodichloromethane, chloroform, chlorodibromomethane,aluminum, iron, lead, mercury, and aluminum, in the airport's drinking water. These past exposuresare no longer occurring because the municipal and airport wells that were impacted bycontamination are no longer in use. In addition, some of the contaminants detected in the municipal and airport water supplies might not be directly related to contamination at the site.
- ATSDR has also identified the following potential human exposure pathways associated with thesite: 1) residents in the site area who use private well water for their household water needs (e.g.,drinking, bathing, showering); 2) former plant employees, site investigators, and trespassers whocould have come into contact with chemicals in raw materials, finished products, and wastesassociated with former site operations, or contaminated soils and sediments resulting from formersite operations; and 3) persons who may have come into contact with surface water (while the plant was in operation) or sediments in the River Gut stream channel downstream of the site.
- Health outcome data for the population surrounding the site was not identified during the gathering of information and data for this public health assessment.
- Data inadequacies include the following: (1) limited sampling data for the VIWAPA Fairplainswells and the VIPA airport supply wells; (2) no sampling data for other VIWAPA wells near thesite, such as the Bethlehem, Negro Bay, Golden Grove wells; and (3) no sampling data or water use information for private wells in the site area.
- No community health concerns about the Island Chemical/Virgin Island Chemical site have been expressed by the citizens of St. Croix.
ATSDR has conducted a toxicological evaluation of contaminants (which may be site-related) in themunicipal and airport drinking water supplies. Based upon that evaluation, ATSDR believes thatadverse noncancer health effects will not occur. In addition, ATSDR believes that there would be noincreased risk of developing cancer from exposures to those contaminants with known carcinogenic endpoints.
ATSDR believes that the public health significance of these potential exposures is likely to beminimal. However, additional information regarding the use and quality of private well water in the site area is necessary to fully evaluate this potential exposure pathway.
Site Characterization Recommendations
- If the VIWAPA Fairplains wells are ever returned to service, sample the wells and the Fairplainsstorage tank to ensure that site-related contaminants are not present in the wells or in the municipal water distribution system at levels of health concern.
- Sample the two VIPA airport supply wells for site-related contaminants if they are ever used in the future to supply drinking water to the airport.
- Consider sampling active VIWAPA municipal supply wells near the site, including the Bethlehem,Golden Grove, and Negro Bay wells, to ensure that these wells are not being impacted bygroundwater contamination from the site.
- If possible, identify private drinking water wells in the site area that could potentially be impactedby contaminants from the site, and sample the identified wells to ensure that site-related contaminants are not present at levels of health concern.
Cease/Reduce Exposure Recommendations
- Restrict access to the site to protect persons from the numerous physical hazards present and toprevent unauthorized persons from entering the site during environmental sampling or remediation activities.
- Implement actions, where appropriate, to prevent groundwater contamination from spreading to down gradient areas and possibly impacting other public and/or private water supply wells.
- Consider institutional controls to prevent future site occupants from using contaminatedgroundwater beneath the site for drinking water supply. Such controls should remain in place untilremediation or natural processes have reduced the contaminant levels to below levels of health concern.
- Provide any environmental sampling/investigative personnel or remedial site workers working inareas where significant site contamination is present, or potentially present (such as the process pitand AST areas), with adequate protective equipment and training in accordance with 29 CFR1910.120. Also, ensure that appropriate National Institute for Occupational Safety and Health(NIOSH) and Occupational Safety and Health Administration (OSHA) guidelines are followed.
Health Activities Recommendations
In accordance with the Comprehensive Environmental Response, Compensation, and Liability Act(CERCLA) of 1980, as amended, the data and information developed in the Island Chemical/Virgin IslandChemical Public Health Assessment have been reviewed by ATSDR's Division of Health Education andPromotion (DHEP) and Division of Health Studies (DHS) for appropriate follow-up health activities. Based on their review, DHEP and DHS have determined that no follow-up health activities are indicated forthe site at this time. However, ATSDR will reevaluate the site for appropriate follow-up health activities iffuture data or information indicates that human exposure to site contaminants is occurring at levels of public health concern.
The Public Health Recommendations and Actions Plan (PHRAP) for the Island Chemical/Virgin IslandChemical site contains a description of actions taken, to be taken, or under consideration by ATSDR and/orother government agencies at or near the site. The purpose of the PHRAP is to ensure that this public healthassessment not only identifies public health hazards, but provides a plan of action designed to mitigate andprevent adverse human health effects resulting from exposure to hazardous substances in the environment. ATSDR and appropriate government agencies will follow up on this plan to ensure that it is implemented.
- Actions Completed
- Actions Planned
- Recommendations for Further Action
ATSDR has conducted two visits to the site in order to verify site conditions and to gather pertinentinformation and data for the site. Harding Lawson Associates (HLA), the contractor for the IslandChemical Company, has completed the EPA Phase I and II RI activities for the site.
As part of the EPA Phase III RI activities, HLA is planning to conduct additional environmental sampling at the site to further characterize the nature and extent of site contamination.
ATSDR will collaborate with the appropriate federal, state, and local agencies to pursue the implementation of the recommendations outlined in this public health assessment.
Environmental Health Scientist
Division of Health Assessment and Consultation
Environmental Health Engineer
Division of Health Assessment and Consultation
ATSDR Regional Representative:
Public Health Advisor
ATSDR Region II
- U.S. Environmental Protections Agency. NPL Fact Sheet, Island Chemical Corp./Virgin Island Chemical Corp. September 1996.
- Harding Lawson Associates. Island Chemical Company, Inc. Remedial Investigation Draft Work Plan. August 1994.
- Harding Lawson Associates. Virgin Island Chemical Site Remedial Investigation Draft Data Summary Report. August 1995.
- U.S. Environmental Protections Agency. Final Hazard Ranking System Documentation, VI Chemical Corporation, Vol. 1. June 1993.
- U.S. Environmental Protection Agency. RCRA Enforcement Interim Report, Berlex Laboratories, St. Croix, VI. March 1986.
- Enviro-Sciences, Inc. Site Inspection Report for Island Chemical Company, St. Croix, U.S. Virgin Islands. April 1987.
- U.S. Environmental Protection Agency. Preliminary Assessment, Removal Site Evaluation, andFunding Authorization Request for a CERCLA Removal Action at the Virgin Island ChemicalCompany, Inc. Site, St. Croix, U.S. Virgin Islands - Action Memorandum from D. Kodama to W. Muszynski. August 1989.
- U.S. Environmental Protection Agency. RCRA Enforcement Report, Berlex Laboratories, St. Croix, Virgin Islands. September 1985.
- Harding Lawson Associates. Draft Supplemental Data Summary Report, Remedial Investigation, Virgin Island Chemical Site. September 1996.
- Harding Lawson Associates. Draft Remedial Investigation Work Plan Addendum - Phase III, Virgin Island Chemical Site. January 1997.
- Houghton Mifflin Company. 1995 Info. Please Almanac, 48th Edition. 1995.
- U.S. Geological Survey. Water Wells on St. Croix, U.S. Virgin Islands, U.S. Geological Survey Open-File Report 91-503. 1994.
- Letter from St. Croix citizen to ATSDR regarding newspaper notice of ATSDR public health assessment for Island Chemical/Virgin Island Chemical site. March 19, 1998.
- U.S. Geological Survey. Mean Concentrations, Deviations and Ranges of Elements in Samples in the (Eastern) Coterminous United States. Cited in ATSDR Public Health Assessment Guidance Manual, 1992.
- U.S. Geological Survey. Gold, Silver, Tellurium, and Spectrographic Analyses for Rock and SoilSamples from the U.S. Virgin Islands, Open-File Report 89-355, 2USGS, 1989. Cited in DraftData Summary Report, Remedial Investigation, Virgin Island Chemical Site, St. Croix, U.S. Virgin Islands, August 1995.
- Harding Lawson Associates. Electronic data sets from the Virgin Island Chemical Site RemedialInvestigation, from files submitted by Harding Lawson Associates to Eastern Research Group, Inc,.on April 30, 1997.
- Friend Laboratory, Inc., National Testing Laboratories, Inc., and WaterTest Corporation ofAmerica. Analytical data sheets for the Virgin Islands Port Authority airport supply wells. October 1998-July 1995.
- Agency for Toxic Substances and Disease Registry. Public health assessment guidance manual. Atlanta: ATSDR, March 1992; DHHS, (PHS).
- Agency for Toxic Substances and Disease Registry. Toxicological profile forbromoform/chlorodibromomethane. Atlanta: ATSDR, December 1990; DHHS publication no. (PHS)TP-90-05.
- Agency for Toxic Substances and Disease Registry. Toxicological profile forbromodichloromethane. Atlanta: ATSDR, December 1989; DHHS publication no. (PHS)TP-89/04.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for chloroform. (update) Atlanta: ATSDR, August, 1995.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for lead. (update) Atlanta: ATSDR, April 1993; DHHS publication no. (PHS)TP-92/12.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for manganese. Atlanta: ATSDR, July 1992; DHHS publication no. (PHS)TP-91/19.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for mercury. (update) Atlanta: ATSDR, May 1994; DHHS publication no. (PHS)TP-93/10.
- Micromedex, Inc. Tomes Integrated Index. CD-ROM, Vol 34. New York: Micromedex, 1997.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for vanadium. Atlanta: ATSDR, July 1992, DHHS publication no. (PHS)TP-91/29.
ATSDR released a draft of this public health assessment for public comment on February 25, 1988. Thepublic comment period ended on April 5, 1988. The only comments ATSDR received on the draft publichealth assessment were from a citizen of St. Croix in a letter dated March 19, 1998. This citizen, a formeremployee of the Island Chemical plant, indicated that during the early 1980s the plant routinely dischargedhigh pH process wastewater, containing various chlorinated solvents, to River Gut without treatment. Thecitizen also stated that he had observed children swimming in the gut near the current Route 66 bridgedownstream of the plant's discharge. He also indicated that plant management commonly disposed of solid"hazardous" waste materials by throwing them into the plant's dumpster for ultimate disposal in the St.Croix landfill.
Response: ATSDR appreciates the valuable information provided by the former Island Chemical employeeand has used the information to supplement the exposure pathways evaluation in the final public health assessment.