PUBLIC HEALTH ASSESSMENT
WAYNESVILLE, HAYWOOD COUNTY, NORTH CAROLINA
The Barber Orchard site is located on approximately 500 acres on a mountain slope south ofHighway 74, about 3 miles west of Waynesville, Haywood County, North Carolina. The entire sitewas an operating commercial apple orchard from the early 1900s to the late 1980s and is now beingdeveloped as a residential community, with about 90 homes and a total of about 300 lots currentlyon site.
During the orchard operation, various mixtures of pesticides were used to control insects androdents. The pesticide mixtures were delivered to trees using a pressurized underground pipingsystem. Leakage of the piping system, product application, and spills during product mixing arethought to have led to contamination of the groundwater and soil. Pesticides, arsenic, and lead havebeen detected in site soils and in private drinking wells on the site.
Based on the available information, the Agency for Toxic Substances and Disease Registry(ATSDR) has concluded that current exposures to site contaminants are not likely to result inadverse health effects. Residents are filtering their water to remove contaminants. In addition,frequently used areas of residential lots with high arsenic and lead soil levels have been cleaned upto safe levels. An ATSDR exposure investigation indicated that lead and arsenic levels in the bodiesof people living on the site were well within normal ranges. Although the chance of a significantexposure occurring is considered to be extremely small, children who habitually eat soil couldexperience reversible health effects if they ate contaminated soil from uncleaned or undevelopedareas of the property.
In the past, residents who regularly drank well water containing the highest levels of pesticides mayhave had a slightly increased risk of cancer or immune system effects. In addition, past exposures ofchildren to the highest concentrations of arsenic and lead in site soils may have increased the risk ofhealth effects. However, because these pathways were disrupted in a relatively short time frame, pastexposures are not likely to lead to health effects at this time.
ATSDR recommends that homeowners with elevated well water contaminants continue to filterwater from their private wells and that new homes be connected to the Waynesville municipal watersupply. ATSDR recommends that people living on the site be informed of ways to avoid potentialhealth effects that children might experience if they eat contaminated soil. ATSDR also recommendsthat appropriate removal and remedial actions, such as EPA and other agencies are carrying out,continue in order to reduce the chance of exposure to high levels of arsenic or lead in soil. Lotsshould be tested for these contaminants before property transfers or development occurs.
Barber Orchard was proposed for the National Priorities List (NPL) on January 11, 2001, and listedon September 13, 2001. The Agency for Toxic Substances and Disease Registry (ATSDR) isrequired by Congress to conduct public health assessments on all sites proposed for the NPL. In thispublic health assessment, ATSDR evaluates the public health significance of the Barber Orchardsite. ATSDR has reviewed available environmental data, potential exposure scenarios, andcommunity health concerns to determine whether adverse health effects are possible. In addition, thispublic health assessment recommends actions to prevent, reduce, or further identify the possibility for site-related adverse health effects.
The Barber Orchard site is located on approximately 500 acres on a mountain slope south ofHighway 74, about 3 miles west of Waynesville, Haywood County, North Carolina [1,2]. The entiresite was an operating commercial apple orchard from the early 1900s to the late 1980s. Although aportion of the property is still used to grow apples, the rest is being developed as a residentialcommunity, with about 90 homes and a total of about 300 lots now on site.(1)
During the time when the entire site was operated as an orchard, various mixtures of pesticides wereused to control insects and rodents. The pesticide mixtures were delivered to trees using apressurized underground piping system. Leakage of the piping system, product application, andspills during product mixing are thought to have led to contamination of the groundwater and soil.Pesticides, arsenic, and lead have been detected in site soils and in private drinking wells on the site.
Based on year 2000 Census data, the town of Waynesville has approximately 9,200 people .Figure 1 shows demographic information for the population of the area surrounding the site. About1,055 people live within a 1-mile radius of the site. The population is mostly white, with less than1% of other ethnic backgrounds.
This description comes from Environmental Protection Agency (EPA) site documents [1,2]. The site extends from near the base of the mountain southward up the slope over 1,000 feet, to an elevation of more than 4,000 feet above mean sea level. The site itself is mostly residential, with approximately 90 houses currently on the site.(1) Most of the houses were constructed in 1993 and 1994. South of the site is a wooded area bisected by the Blue Ridge Parkway. The land east and west of the site is generally wooded and rural residential, containing clusters of houses. The northern part of the site is in a mountain valley, through which Richland Creek flows west to east. Near the base of the hill on adjacent property east of the site is an operating apple orchard, and northeast of the site is a child care center.
Seven small on-site and near-site drainages flow northward down the mountain to Richland Creek atthe base of the site. These drainages are each less than 2 feet wide and only a few inches deep. Onedrainage originates from a spring that is the source for a series of small on-site ponds. An overflowpipe in each of the ponds flows back into a drainage that flows into the next pond in the series.
Several of the homes on the site have private drinking water supply wells. According to EPAofficials, all but two homes have been fitted with filtration systems to reduce contaminants that maybe present in the drinking water.(2) Within 2 to 3 years, municipal water system lines will be built andavailable to all site residents.(3)
ATSDR conducted two health consultations in 2000 regarding the chemicals found in groundwatersamples collected at the Barber Orchard Site in 1999 [4,5]. Pesticide results from samples collectedat private wells were reviewed to evaluate public health concerns. The primary pesticides detectedwere the alpha, beta, gamma, and delta (a, b, g and d) isomers of benzene hexachloride (BHC),endrin, endrin ketone, and endosulfan sulfate. Results from over 300 samples collected by EPA andthe state of North Carolina were reviewed during these consultations. ATSDR concluded that theconcentration of a- and b-BHC in groundwater posed a public health hazard for children drinkingthe water for prolonged periods. Alternate water supplies for contaminated wells and continuedmonitoring of groundwater on a quarterly basis were recommended.
In 1999, ATSDR conducted an exposure investigation, in cooperation with the Haywood CountyHealth Department, to determine the levels of lead and arsenic in the bodies of people living on site. Blood samples were collected for lead analysis, and urine samples were collected for arsenicanalysis. The highest levels of lead and arsenic measured were well below levels of concern, andthere was no indication that follow-up testing of the residents was needed. ATSDR recommendedthat undeveloped lots be characterized for contaminants prior to any construction, development, or earth-moving activities.
The data evaluated in this document came from the following sources:
- sampling of private drinking water wells by the North Carolina Department of Environment and Natural Resources in 1999 ;
- sampling of soil in the former orchard by the NC Department of Agriculture in 1999 ;
- sampling of soil and drinking water by EPA in 1999 ; and
- sampling of soil, sediment, private drinking water wells, groundwater monitoring wells, and surface water by EPA as part of the remedial investigation (provided by EPA electronically) .
The data evaluated include the initial characterization of soils and groundwater at the site. Theremoval action which was completed in August 2000 resulted in the removal of soil from severalhighly contaminated residential lots. In addition, most of the homeowners in Barber Orchard arecurrently treating groundwater with carbon filters, and their houses are scheduled to be connected tothe city of Waynesville's public water supply. Because no data were excluded from considerationhere, it should be understood that the complete data set will likely overestimate exposure pathwaysof potential concern. The conclusions reached in this document are based on the data available atthis time and may be modified if new environmental data become available.
The process by which ATSDR evaluates the possible health impact of contaminants is summarizedhere and described in more detail in Appendix A. ATSDR uses comparison values (CVs) todetermine which chemicals to examine more closely. CVs are concentrations of chemicals in theenvironment (air, water, or soil) below which no adverse human health effects are expected to occur.CVs are based on toxicological and epidemiological studies of acute (1-14 days), intermediate (15-364 days), or chronic (365 days or more) exposure. We use the available CV that most closelymatches the exposure duration of interest. Exceeding a CV does not mean that health effects willoccur, but it indicates that more evaluation is needed.
If the level of contamination at the site is greater than the CV, further evaluation will focus onidentifying which chemicals and exposure situations could be a health hazard. Child and adultexposure doses are calculated for the exposure scenario of interest. Exposure doses are the estimatedamounts of a specific contaminant that people come in contact with under specified exposuresituations. These exposure doses are compared to appropriate health guidelines for that chemical.Health guideline values are considered safe doses; that is, health effects are unlikely below this level.If the exposure dose for a chemical is greater than the health guideline, then the exposure dose iscompared to known health effect levels identified in ATSDR's Toxicological Profiles. If thechemical of concern is a carcinogen, the cancer risk is also estimated. These comparisons are thebasis for stating whether the exposure is a health hazard.
The following sections describe the various ways people could come into contact with contaminantsat the site. Each of these is called an exposure pathway. Appendix B summarizes the possibleexposure pathways. If people are unlikely to be exposed to contaminants in a given pathway, thenthat pathway will not be evaluated further for human health risks.
People drinking groundwater could be exposed to contaminants in the groundwater beneath the site.ATSDR evaluated contaminant data collected from both private wells and groundwater monitoringwells. Table 1 lists the contaminants of concern, compounds that were detected at least once abovethe corresponding CV.
|Contaminant||Concentration Range in parts per billion (ppb)||Frequency of Detection / Total||Comparison Value (CV) in ppb||CV Source1|
|Aluminum||ND - 150,000||15 / 45||20,000||EMEG2|
|Arsenic||ND - 13||2 / 46||3 / 0.2||EMEG / CREG3|
|Barium||3 - 1,900||45 / 45||700||RMEG4|
|Beryllium||ND - 8||1 / 45||10 / 4||EMEG / MCL5|
|Chromium||ND - 220||12 / 45||30||RMEG|
|Lead||ND - 72||11 / 45||15||AL6|
|Manganese||ND - 1,300||18 / 45||500||RMEG|
|Nickel||ND - 130||6 / 45||700 / 100||RMEG / LTHA7|
|Vanadium||ND - 350||8 / 45||30||EMEG|
|a-BHC||ND - 0.987||68 / 192||80 / 0.006||EMEG / CREG|
|b-BHC||ND - 0.14||38 / 192||6 / 0.02||EMEG / CREG|
|d-BHC||ND - 0.8||53 / 192||none8||N/A|
|g-BHC||ND - 2.61||92 / 192||0.1||EMEG|
|Dieldrin||ND - 0.006||1 / 45||0.5 / 0.002||EMEG / CREG|
|1 These comparison values are described in Appendix A. |
2 EMEG = environmental media evaluation guide.
3 CREG = cancer risk evaluation guide.
4 RMEG = remedial media evaluation guide.
5 MCL = maximum contaminant level.
6 AL = EPA action level.
7 LTHA = life time health advisory.
8 no CV available.
Next, exposure doses were calculated for the contaminants of concern in Table 1. The worst casewas assumed to be a 2-year-old weighing 13.3 kilogram (kg) drinking 1 liter per day of watercontaining the maximum concentration of each contaminant for 350 days out of the year . Theexposure dose estimated through this procedure was compared with health guideline values andtoxicological information for the contaminant of concern. For evaluating the risk of cancer, weassumed that adults weighing 70 kg would be exposed to the maximum concentration of eachcontaminant for 350 days a year for a lifetime (i.e., 70 years). When this analysis was performed,the doses for beryllium, nickel, b-BHC, d-BHC, and dieldrin were found to be lower than theapplicable cancer and noncancer health guidelines, so these compounds were dropped from furtherconsideration [10,11,12,13]. The following sections describe the evaluation of the remainingcontaminants of concern from Table 1.
a-BHC and g-BHC (Lindane)
The dose calculated for a-BHC is lower than ATSDR's chronic oral minimal risk level (MRL) of0.008 milligrams per kilogram per day (mg/kg/day) . No noncancer health effects are expectedfrom exposure to this contaminant in water. Based on animal studies, a-BHC is a probable humancarcinogen . Exposure to the maximum a-BHC concentration measured in a water well wouldpresent a low to moderate increased lifetime risk of cancer if exposures were daily for 70 years. Theactual risk of people who drank the water developing cancer is lower, however, since exposures havebeen stopped and the duration of past exposures was much shorter than 70 years.
The dose for g-BHC is higher than the MRL of 0.00001 mg/kg/day for intermediate oral exposure. This MRL is based on a lowest observed adverse effect level (LOAEL) of 0.012 mg/kg/day instudies on mice. The calculated dose is 60 times smaller than the LOAEL. At the LOAEL, effects onthe immune systems of female mice were observed. g-BHC is classified as a possible humancarcinogen , but because there is no oral cancer slope factor (CSF, defined on page 28 inAppendix C) for g-BHC, it was not possible to evaluate carcinogenic risk. The risk of cancer ornoncancer health effects in people who drank the water is minimal because current exposures havestopped and the duration of past exposures was short.
Many wells on the site had contaminant levels much lower than the maximum (i.e., too low to causehealth effects). Homeowners at the site have been informed of the results of testing of their wells.Subsequently, all but two homes have had filtration systems installed to reduce contaminants in thewater, effectively disrupting this exposure pathway. Past exposures from this pathway are notexpected to lead to the long-term health effects mentioned above because the pathway was disruptedand exposure duration was relatively short.
Exposure to arsenic from drinking private well water is not likely to result in health effects inchildren or adult residents. This compound was detected at a low frequency, and the wells in whichis was detected were monitoring wells no people drank. Even if people did drink this water, it wouldnot be expected to result in health effects, because the calculated dose based on regularly drinkingwater containing the maximum concentration of arsenic is an order of magnitude lower than theLOAEL of 0.014 mg/kg/day . Based on human epidemiological studies, arsenic is a knowncarcinogen . Based on the fact that arsenic was not detected in private wells, exposure to arsenicin drinking water is not expected to result in an increased cancer risk.
Exposure to lead from drinking private well water is not likely to result in health effects in childrenor adult residents. Only two private wells had lead levels above the screening value of 15 ppb; thesecontained 18 and 19 ppb of lead.
The level of lead in blood is a good measure of recent exposure to lead and also correlates well witha wide range of possible health effects [?]. Children are especially sensitive to lead; levels inchildren's blood of 10 micrograms per deciliter (µg/dL), and perhaps lower, have been associatedwith small decreases in IQ and slightly impaired hearing and growth. A slope factor for the increasein blood lead concentration per increase in water lead concentration for infants has been calculatedas 0.04 µg/dL blood per part per billion (ppb) lead at water lead levels above 15 ppb; thecorresponding slope factor for school children was found to be 0.03 µg/dL per ppb [?]. Using thehighest concentration of lead measured in a private well (19 ppb), blood lead concentrations forinfants and school children would be expected to rise by less than 1 µg/dL. This would be unlikelyto result in detectable health effects.
Two monitoring wells contained higher concentrations of lead, with a maximum concentration of 72ppb measured. Drinking this water would result in a slightly higher risk of health effects. Becausepeople are filtering their water and will be connected to the municipal system, drinking waterexposure to lead is not of concern.
Other Metals (Aluminum, Barium, Chromium, Manganese, and Vanadium)
The remaining metals were only detected above the screening value in monitoring wells. Because noone has ever or will ever drink this water, this is not an exposure of concern. The levels of metals inthe private wells were all lower than screening values and therefore not expected to result in anyhealth effects.
People on the site could come into direct contact with contaminants in soil. They could getcontaminated soil on their skin, or they might accidentally eat or breathe in soil particles. Table 2lists the contaminants that were found in the soil on site at levels above soil CVs.
|Contaminant||Concentration Range in parts per million (ppm)||Frequency of Detection / Total||Comparison Value (CV) in ppm||CV Source1|
|Arsenic||ND - 1,340||418 / 448||20 / 0.5||EMEG2 / CREG3|
|Beryllium||ND - 2||83 / 162||50 / 0.1||EMEG / SSL4|
|Iron||3,700 - 70,000||162 / 162||23,000||R9 PRG5|
|Lead||ND - 3,090||356 / 356||400||SSL4|
|Thallium||ND - 7||91 / 252||5.2||R9 PRG|
|4-4'-DDD||ND - 83||172 / 289||3||CREG|
|4-4'-DDE||ND - 9||266 / 326||2||CREG|
|4-4'-DDT||ND - 52||266 / 319||30 / 2||RMEG6 / CREG|
|a-BHC||ND - 8||16 / 161||400 / 0.1||EMEG / CREG|
|b-BHC||ND - 8||75 / 210||30 / 0.4||RMEG / CREG|
|g-BHC (lindane)||ND - 8||26 / 174||20 / 0.5||RMEG / SSL|
|Dieldrin||ND - 3||98 / 219||3 / 0.04||EMEG / CREG|
|Endrin||ND - 76||201 / 291||20||EMEG|
|Heptachlor epoxide||ND - 0.6||14 / 162||0.7 / 0.08||RMEG / CREG|
|1 These comparison values are described in Appendix A. |
2 EMEG = environmental media evaluation guide.
3 CREG = cancer risk evaluation guide.
4 SSL = EPA soil screening level.
5 R9 PRG = EPA region 9 preliminary remediation goal.
6 RMEG = remedial media evaluation guide.
Next, exposure doses were calculated for the contaminants of concern in Table 2. Generally, dosesfor soil are calculated using average contaminant concentration rather than the maximum, sincepeople contact soil from many different areas in their daily activities. However, to be conservative,the maximum value for each contaminant was used to calculate exposure dose. In some cases, the95th percentile of the data was also used. In addition, acute exposure was calculated for arsenic, sincechildren in a residential setting might exhibit soil pica behavior (excessive soil consumption). Thisbehavior occurs in a small percentage of young children and is extremely rare in children over 6years old .
The worst-case chronic exposure was assumed to be a 2-year-old weighing 13.3 kg contacting soilcontaining the maximum concentration of each contaminant all day for 350 days out of the year .Children of this age are assumed to take in (ingest) 200 milligrams (mg) of soil per day . Theexposure dose estimated through this procedure was compared with health guideline values andtoxicological information for the contaminant of concern. Acute exposure to arsenic was calculatedassuming a 13.3 kg toddler ingesting 5,000 mg of soil in a single event . We assumed thatchildren exhibiting soil pica behavior are young and restricted to play only in the "yard" area neartheir house. For evaluating the risk of cancer, we assumed that adults weighing 70 kg would beexposed to the maximum concentration of each contaminant for 350 days a year for a lifetime (70years). Adults are assumed to ingest 50 mg of soil a day . When this analysis was performed,doses for beryllium, iron, thallium, 4,4'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), a-BHC, b-BHC, dieldrin, and heptachlor epoxide were found to be lower than the applicable cancerand/or noncancer health guidelines, so these contaminants were dropped from further consideration[10,17,18,19,12,13,20]. The following sections describe the evaluation of the remainingcontaminants of concern from Table 1.
Regular exposure of children to the maximum concentration of arsenic in site soils could causeshort- and long-term noncancer health effects. In addition, exposure to arsenic in soil over manyyears could increase a resident's chance of cancer. However, these conclusions are based onmaximum arsenic concentrations which 1) may no longer exist at the site and 2) are especiallyconservative for determining the risk of chronic effects. In addition, an exposure investigationconducted by ATSDR in 1999 showed no elevated urine arsenic levels in site residents tested .
The acute dose based on a child exhibiting soil pica behavior ingesting soil with the maximumarsenic concentration is over ten times higher than the acute LOAEL of 0.05 mg/kg/day . At theLOAEL, transient effects, including nausea, vomiting, and diarrhea, may occur. Children exposed tothe average arsenic concentration and not exhibiting pica behavior are unlikely to experience acutehealth effects. Although the acute risk was of concern in the past, the current risk of acute healtheffects is low. This is because the "yard" areas of lots with the highest arsenic levels, where youngchildren most likely to exhibit pica behavior would play, have already been cleaned up. However, inthe unlikely event that a child exhibiting pica behavior consumed soils containing extremely higharsenic levels from undeveloped lots or uncleaned areas of developed lots, transient health effects,such as nausea, vomiting, and diarrhea, would be possible.
The chronic child exposure dose based on the maximum arsenic concentration in soil is 0.019mg/kg/day. This is higher than the long-term no observed adverse effect level (NOAEL) of 0.0008mg/kg/day and slightly higher the long-term LOAEL of 0.014 mg/kg/day . At the LOAEL,effects such as skin changes have been observed. The actual risk of chronic health effects is lowerthan predicted, however, because the some areas of lots with the highest arsenic levels have alreadybeen cleaned up and because children would be exposed to an average concentration lower than themaximum. The adult exposure dose to arsenic is even lower than the child dose. No long-termnoncancer health effects are expected to occur in adults from this exposure.
Based on human epidemiological studies, arsenic is a known carcinogen . Exposure to themaximum concentration of arsenic found in soil, 1340 parts per million (ppm), would present amoderate to high increased lifetime risk of cancer if exposures occurred daily for 70 years. Theactual cancer risk is lower, however, since people contact an average arsenic concentration, not themaximum, and duration of exposure is shorter because the subdivision is relatively new. The cancerrisk for people contacting the estimated 95th percentile of arsenic (196 ppm) in soil for many years is low to moderate.
Calculations using past and current soil results show that there is an increased risk of health effectsoccurring from exposure to the maximum concentration of lead in site soil. However, an exposureinvestigation conducted by ATSDR in 1999 showed that none of the site residents had elevatedblood lead levels . In addition, by the year 2000, areas of the lots where children could haveregular contact with soil containing lead higher than EPA's soil screening level (400 ppm) had beencleaned up to safe levels. Therefore, ATSDR does not consider lead to pose a health hazard at thistime.
In general, the level of lead in a person's blood, typically measured in micrograms per deciliter(µg/dL), gives a good indication of recent exposure to lead and also correlates well with healtheffects. The Centers for Disease Control and Prevention (CDC) considers children to have elevatedlead levels if the amount of lead in the blood is 10 µg/dL or higher . However, some studieshave indicated that even lower levels may be associated with small decreases in IQ and slightlyimpaired hearing and growth. If we use the most protective correlation between blood lead levelsand soil lead concentration found in epidemiological studies (0.0068 µg/dL increase in blood leadlevel for each additional ppm of lead in soil) and the estimated 95th percentile lead concentrationmeasured in soil (926 ppm), then the predicted blood lead level increase is about 6.3 µg/dL .The risk of this large an increase in blood lead level is unlikely, however, because highly-used areasof the most contaminated yards have been cleaned up. Acute exposures to lead are not considered amajor concern at this site, because activities of the children most likely to exhibit pica behavior ( lessthan 6 years old) are assumed to be concentrated in cleaned-up "yard" areas. Older children are lesslikely to exhibit pica behavior and are less susceptible to lead's harmful effects.
Animal data indicate that lead is a probable human carcinogen . However, because no cancerslope factor for lead exists, it was not possible to evaluate carcinogenic risk.
4,4'-DDD and 4,4'-DDT
The doses for exposure to 4,4'-DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane) and 4,4'-DDT(1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) in soil are both higher than ATSDR's intermediateoral MRL for 4,4'-DDT. The dose is 50 times lower than the NOAEL from animal studies (0.05mg/kg/day) . The actual exposure dose will be even lower than calculated, because chronicexposures would be to the average concentration rather than the maximum. No health effects areexpected from exposure to these contaminants in soil.
The exposure dose for g-BHC (lindane) in soil is 120 times smaller than the intermediate durationoral LOAEL from animal studies (0.012 mg/kg/day) . At the LOAEL, effects on the immunesystems of female mice have been observed . The actual exposure dose will be lower thancalculated, because chronic exposures would be to the average concentration rather than themaximum. Exposure to g-BHC in soil is not expected to lead to health effects.
g-BHC is a possible human carcinogen . However, there is no oral cancer slope factor for g-BHC, so it was not possible to evaluate carcinogenic risk.
The dose for exposure to the maximum concentration of endrin in soil is 25 times smaller than theNOAEL from animal studies (0.025 mg/kg/day) . The actual exposure dose will be lower thancalculated, because chronic exposures would be to the average concentration rather than themaximum. Exposure to endrin in soil is not expected to lead to health effects.
Contaminants may evaporate into the air (volatilize) from the soils or water on site, or contaminatedsoil particles may be transported as fugitive dust. People could breathe in (inhale) thesecontaminants or get them on their skin. There are no data on air contaminants from the site.However, the main contaminants remaining in the soils are not very volatile. Therefore,volatilization of contaminants from soil or water is considered an incomplete pathway of exposure.The only exposure route for air that is considered complete is inhalation of contaminated soil in theform of dust from construction activities.
Residents and site visitors may be exposed to contaminants by inhaling dust created by constructionactivities on the site. To evaluate this pathway, we used the same data set as for the soil ingestionpathway discussed above. We assumed a dust loading factor of 8×10-6 kilogram per cubic meter(kg/m3) to estimate the chemical concentration in air from that in soil. For initial screening, thesampling results were compared to CVs for air. As shown in Table 3, several compounds weredetected at least once at levels above the corresponding CV for inhalation exposure.
|Contaminant||Concentration Range in parts per million (ppm)||Maximum Air Concentration in micrograms per cubic meter (µg/m3)||Comparison Value in µg/m3||CV Source1|
|Arsenic||ND - 1340||10.7||0.0002||CREG2|
|4-4'-DDD||ND - 83||0.7||0.026||R9 PRG3|
|4-4'-DDE||ND - 9||0.1||0.018||R9 PRG|
|4-4'-DDT||ND - 52||0.4||0.01||CREG|
|Aldrin||ND - 0.4||0.003||0.0002||CREG|
|a-BHC||ND - 8||0.1||0.0006||CREG|
|b-BHC||ND - 8||0.1||0.002||CREG|
|d-BHC||ND - 4||0.03||0.0006||CREG for a-BHC|
|g-BHC (lindane)||ND - 8||0.1||0.0052||R9 PRG|
|Dieldrin||ND - 3||0.02||0.0002||CREG|
|Heptachlor epoxide||ND - 0.6||0.0048||0.00069||R9 PRG|
|1 These comparison values are described in Appendix A. |
2 CREG = cancer risk evaluation guide.
3 R9 PRG = EPA region 9 preliminary remediation goal.
To determine average exposure to soil particles through the inhalation route, we assumed thatpeople are exposed for 2 hours per day, 60 days per year. The concentrations were multiplied byfactors to account for this lower exposure. For all the compounds except arsenic, the corrected airconcentrations resulting from this calculation were very near or below the corresponding healthguideline and/or the cancer risk was within EPA's acceptable range (less than 1×10-4, or 1 in10,000). Inhalation exposure to arsenic over many years at the maximum concentration and at theabove assumed frequency would present a low to moderate predicted increased risk of cancer.However, the actual risk is much lower, because people would be exposed to an averageconcentration, rather than the maximum, and because construction activities will not continue formany years. ATSDR does not consider inhalation of dust from construction activities to pose anundue public health risk.
According to residents of the site, corn has been grown on the site and sold for human consumption.The main contaminant of concern for this pathway is arsenic. No data on arsenic levels in corngrown on the site have been collected to date. However, there is guidance on predicting pollutantconcentrations in vegetables given soil concentrations . Using uptake factors given in thisguidance, the maximum arsenic concentration measured at the site, and average per capita cornconsumption, the maximum daily arsenic intake from corn is predicted to be around 19 µg/day,within the normal arsenic dietary intake range [22,9,14]. This calculation is conservative, becausethe corn would be exposed to, and uptake, an average arsenic concentration, rather than themaximum. Also, people would be unlikely to eat only corn grown on site. No health effects areexpected from eating corn grown on site.
Water from surface runoff and ponds on the site may pick up contaminants from soils, sediments, orgroundwater. No use of this water for drinking water purposes was identified, but people who liveon or visit the site may accidentally ingest some of the surface water or get it on their skin. Thirty-eight surface water samples were collected during the remedial investigation. All compoundsdetected were at levels lower than screening CVs for incidental exposure.
People who live on or visit the site may accidentally ingest some of the sediments from the ponds orstreams on the site or get them on their skin. To be conservative, our initial screening assumedsediments would be contacted like soil particles. Thirty-six sediment samples were collected duringthe remedial investigation. The only compounds found above screening levels were a-BHC, dieldrin,benzo(a)pyrene, arsenic, beryllium, and iron. All except arsenic and iron were detected infrequentlyand only slightly above the cancer effect CV. The doses from exposure to these contaminants insediments are much lower than health guidelines, and therefore no health effects are expected[12,13,23,14,10,17]. The maximum arsenic and iron sediment levels are lower than the maximumlevels in soil reported above. Since sediment is contacted much less frequently than soil, thesecontaminants are not expected to pose a significant additional risk.
ATSDR recognizes that infants and children may be more vulnerable to exposures than adults incommunities faced with contamination of their air, water, soil, or food. This vulnerability is a resultof the following factors:
- Children are more likely to play outdoors and bring food into contaminated areas.
- Children are shorter, resulting in a greater likelihood to breathe dust, soil, and heavy vapors close to the ground.
- Children are smaller, resulting in higher doses of chemical exposure per body weight.
- The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages.
Because children depend completely on adults for risk identification and management decisions,ATSDR is committed to evaluating their special interests at the site as part of the ATSDR ChildHealth Initiative.
The major exposure routes for children living on the site are ingestion of drinking water andingestion of surface soil. Please refer to the appropriate section for discussion of the possible healtheffects for children.
The Superfund law requires that health outcome data be considered in a public health assessment.Health outcome data may include mortality information (e.g., the number of people dying from acertain disease) or morbidity information (e.g., the number of people in an area getting a certaindisease or illness). In order to thoroughly evaluate health outcome data as it relates to a hazardouswaste site, the following elements are necessary: (1) the presence of a completed human exposurepathway, (2) sufficiently high contaminant levels to result in measurable health effects, (3) sufficientnumber of people in the completed pathway for the health effect to be measured, and (4) a healthoutcome database in which disease rates for populations of concern can be identified.
The site does not meet the requirements for including an evaluation of health outcome data in apublic health assessment. While there are completed human exposure pathways at this site, thecontaminant levels, exposures, and exposed population are not great enough to result in ameaningful measurement of health outcome data.
On November 1, 2001, ATSDR held a public availability session at Saunook Fire Station inWaynesville. The meeting was attended by approximately 5 residents of Barbers Orchard, as well asseveral officials from city, state, and federal organizations. The community voiced several concernsregarding human health on site. In addition, other community members expressed their concernsabout the site by telephone.
In addition to the November availability session, the Barber Orchard Public Health Assessment wasavailable for public review and comment from April 24 to May 23, 2002, at the Haywood CountyPublic Library in Waynesville, NC. The public comment period was announced in localnewspapers, and fact sheets announcing the availability of the public health assessment were mailedto residents near the site. The PHA was also sent to several federal, state, and local officials. Nowritten comments were received.
The health concerns are summarized and addressed below:
Concern: When I develop my property, is there a concern for putting in a well?
Response: Most of the wells tested to date had contaminant levels below levels of concern.However, to avoid questions about water safety, ATSDR recommends that properties developed atfuture dates be connected to the Waynesville municipal water system.
Concern: My lot was tested and had 5.4 ppm of arsenic and 30 ppm of lead in the soil. Is there aconcern about building a house on my undeveloped lot?
Response: The values quoted by this homeowner are both lower that ATSDR comparison values(discussed in Appendix A). No health effects would be expected from exposure to contaminants atthese levels.
Concern: Corn was grown on the site and sold for human consumption. The site where the cornwas grown was not tested. Was/is the corn safe to eat? What are the results of the study WesternCarolina University did on corn uptake of contaminants?
Response: This concern is addressed on page 13. No health effects are expected from eating corngrown on the site. According to a Western Carolina University researcher, the results of vegetableuptake experiments have not been published yet.(4) ATSDR will consider the results of such studies, ifthey are available, in future versions of this document.
Concern: Is there an immediate health threat from living on the orchard? Are we going to getcancer next year?
Response: Based on the currently available data, there is no immediate health threat from living onproperties in Barber Orchard. The health effects discussed in this document are based on long termexposures (over many years) and conservative, protective assumptions. The cleanup of the site willensure that long-term exposures are minimized.
Concern: What is the bottom line on what's going to be done on the site?
Response: According to EPA officials, the record of decision (ROD) for Barber Orchard will beissued by December of 2002. The ROD will detail the cleanup plan selected for the site.
Concern: We got expensive filters for our water and I want EPA to test my filtered water (notunfiltered water), to make sure it's safe.
Response: At the public meeting on November 1, 2001, EPA's remedial project manager statedthat testing of filtered as well as unfiltered water would take place during the remedial investigation.
Concern: Will dust and debris from construction / remedial activities affect people's health?
Response: The major exposure pathway resulting from construction activities is breathing in(inhaling) dust. This pathway is discussed on page 12. People on the site are not expected to exhibithealth effects from inhaling dust from construction or remedial activities on the site.
Concern: How has the site affected the health of homesteaders who have been living near thesite for many years? Some of them have drunk water from springs on the site.
Response: Our analysis showed that there could be an increased risk of cancer if adults wereexposed to the highest levels of arsenic in site soils for long periods of time. This would be unlikelyfor someone not living on the site. In addition, the current data indicate that the level ofcontaminants in surface water such as springs is too low to result in health effects. Therefore, no site-related health effects are expected in homesteaders.
Because people were exposed in the past to a-BHC and g-BHC in drinking water at levels that mayslightly increase the risk of cancer or immune system effects and because soil contained levels ofarsenic and lead that could cause short-and long-term health effects, ATSDR considers BarberOrchard a past public health hazard. The site currently poses no apparent public health hazardbecause people are no longer drinking untreated water and because contaminated soils smallchildren could contact frequently have been cleaned up. The site could pose a future health hazard ifundeveloped lots are not characterized properly and remediated, if necessary, before new residential construction.
- Most well water samples had levels of contaminants too low to cause health effects.However, a few wells contained a-BHC and g-BHC at levels that may slightly increase therisk of cancer or immune system effects. Homeowners are now aware of the contaminantlevels in their wells and are filtering the water, and connections to the municipal watersupply will be available within two years.
- Soils in residential areas contain elevated levels of arsenic, lead, and pesticides. Exposure ofsmall children to the highest levels of arsenic and lead in soils could cause short- and long-term health effects. In addition, the level of arsenic in soils may result in a low to moderateincreased risk of cancer if adults were exposed for long periods of time. The actual risk ofhealth effects, including cancer, is now low because the most highly used areas of highlycontaminated developed lots have been cleaned up. Although the chance of exposure isextremely small, children exhibiting pica behavior could experience health effects if theywere to be exposed to arsenic and lead in uncleaned or undeveloped areas. Pesticide levels insoils are too low to result in health effects.
- Many years of breathing in dust from construction activities containing the highest arsenicconcentration would result in a low to moderate increased risk of cancer. However, theactual risk is much lower since predicted risk was based on maximum rather than averagesoil concentrations and since construction activities on contaminated soil will take place for only a few years at most.
- Corn grown on the site is not likely to contain high enough levels of contaminants to result inhealth effects.
- Contaminants in surface water and sediments are too low to result in health effects.
- ATSDR recommends that homeowners with elevated well water contaminants continue tofilter water from their private wells. Filtered water should be tested periodically to ensurethat contaminant levels are below drinking water standards. New homes should be connectedto the Waynesville municipal water supply.
- ATSDR recommends that people living on the site be informed of ways to avoid potentialhealth effects that children might experience if they eat contaminated soil.
- ATSDR recommends that appropriate removal and remedial actions, such as EPA and otheragencies are carrying out, continue in order to reduce the chance of exposure to high levelsof arsenic or lead in soil or dust. Lots should be tested for these contaminants, andremediated if necessary, before property transfers or development occurs.
The Public Health Action Plan for the site contains a description of actions have been or will betaken by ATSDR and/or other government agencies at the site. The purpose of the Public HealthAction Plan is to ensure that this public health assessment not only identifies public health hazards,but provides a plan of action designed to mitigate and prevent adverse human health effects resultingfrom exposure to hazardous substances in the environment. Included is a commitment on the part ofATSDR to follow up on this plan to ensure its implementation. The public health actions that havebeen completed are as follows:
- ATSDR published two health consultations in which it reviewed groundwater sampling data to determine risk from drinking the water.
- ATSDR and the Haywood County Health Department conducted an exposure investigation to determine levels of arsenic and lead in residents' bodies.
- ATSDR conducted a site visit in order to verify site conditions and to gather pertinent information and data for the site.
- ATSDR held a public availability session to gather health concerns from the site community.
- Residents and EPA installed filters to reduce contaminants in private well water.
- ATSDR distributed a fact sheet on the findings of this public health assessment to citizens living on and near the site.
The public health action to be implemented is as follows:
- The city of Waynesville is extending the municipal water system to reach homes in the site area.
- ATSDR will review additional environmental sampling results for the site to evaluate any changes in possible public health implications.
ATSDR will reevaluate and expand the Public Health Action Plan when needed. Newenvironmental, toxicological, or health outcome data or the results of implementing the aboveproposed actions may determine the need for additional actions at this site.
Authors of Report
Jill J. Dyken, Ph.D., P.E.
Environmental Health Scientist
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
W. Allen Robison, Ph.D.
Superfund Site Assessment Branch
Division of Health Assessment and Consultation
ATSDR Region 4
Community Involvement Specialist
Community Involvement Branch
Division of Health Assessment and Consultation
Health Education Specialist
Health Education Branch
Division of Health Education and Promotion
- Black and Veatch. Final work plan, remedial investigation/feasibility study for BarberOrchard Site. Prepared for the US Environmental Protection Agency, Region IV. Alpharetta,GA; May 2001.
- Black and Veatch. Final baseline risk assessment work plan, remedialinvestigation/feasibility study for Barber Orchard Site. Prepared for the US EnvironmentalProtection Agency, Region IV. Alpharetta, GA; May 2001.
- US Census Bureau. Advance national summary file 1 (SF1) 100 percent data. DP-1. Profileof general demographic characteristics: 2000. Washington: US Census Bureau; 2001.Available electronically at http://factfinder.census.gov/servlet/BasicFactsServlet .
- Agency for Toxic Substances and Disease Registry. Health consultation for Barber'sOrchard, Waynesville, Haywood County, North Carolina. Atlanta: US Department ofHealth and Human Services; April 2000.
- Agency for Toxic Substances and Disease Registry. Health consultation for Barber'sOrchard, Waynesville, Haywood County, North Carolina. Atlanta: US Department ofHealth and Human Services; September 2000.
- Agency for Toxic Substances and Disease Registry. Exposure investigation for Barber'sOrchard, Waynesville, Haywood County, North Carolina. Atlanta: US Department ofHealth and Human Services; June 2000.
- US Environmental Protection Agency. Barber Orchard HRS Documentation Record.November 2000.
- US Environmental Protection Agency. Excel files containing remedial investigation rawdata. Provided electronically, June 2002.
- US Environmental Protection Agency. Exposure factors handbook. Washington, DC: USEnvironmental Protection Agency. Office of Research and Development. EPA/600/C-99/001; February 1999.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for beryllium:update. Atlanta: US Department of Health and Human Services; 2000.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for nickel: update.Atlanta: US Department of Health and Human Services; 1997.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for a-, b-, g-, andd-hexachlorocyclohexane: update. Atlanta: US Department of Health and Human Services;1999.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for aldrin/dieldrin: update. Atlanta: US Department of Health and Human Services; 2000.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for arsenic:update. Atlanta: US Department of Health and Human Services; 2000.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for lead: update.Atlanta: US Department of Health and Human Services; 1999.
- Agency for Toxic Substances and Disease Registry. Summary report for the ATSDR soil-pica workshop, June 2000, Atlanta, Georgia. Atlanta: US Department of Health and HumanServices; March 2001.
- Food and Nutrition Board of the Institute of Medicine. Dietary reference intakes for vitaminA, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum,nickel, silicon, vanadium, and zinc. Institute of Medicine; 2001.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for thallium.Atlanta: US Department of Health and Human Services; 1992.
- Agency for Toxic Substances and Disease Registry. Toxicological profile forDDT/DDD/DDE: update. Atlanta: US Department of Health and Human Services; 2000.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for heptachlor/heptachlor epoxide: update. Atlanta: US Department of Health and Human Services; 1993.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for endrin andendrin aldehyde: update. Atlanta: US Department of Health and Human Services; 1996.
- US Environmental Protection Agency. A guide to the biosolids risk assessments for the EPApart 503 rule. Available electronically at http://www.epa.gov/owm/bio/503rule/ . Lastmodified August 28, 2001.
- Agency for Toxic Substances and Disease Registry. Toxicological profile for polycyclicaromatic hydrocarbons (PAHs): update. Atlanta: US Department of Health and HumanServices; 1995.
In evaluating these data, ATSDR used comparison values (CVs) to determine which chemicals to examine more closely. CVs are the contaminant concentrations found in a specific media (air, soil, or water) and are used to select contaminants for further evaluation. CVs incorporate assumptions of daily exposure to the chemical and a standard amount of air, water, and soil that someone may inhale or ingest each day.
As health-based thresholds, CVs are set at a concentration below which no known or anticipatedadverse human health effects are expected to occur. Different CVs are developed for cancer andnoncancer health effects. Noncancer levels are based on valid toxicologic studies for a chemical,with appropriate safety factors included, and the assumption that small children (22 pounds) andadults are exposed every day. Cancer levels are the media concentrations at which there could be aone in a million excess cancer risk for an adult eating contaminated soil or drinking contaminatedwater every day for 70 years. For chemicals for which both cancer and noncancer numbers exist, thelower level is used to be protective. Exceeding a CV does not mean that health effects will occur,just that more evaluation is needed.
CVs used in this document are listed below:
Environmental Media Evaluation Guides (EMEGs) are estimated contaminantconcentrations in a media where non-carcinogenic health effects are unlikely. The EMEG isderived from ATSDR's minimal risk level (MRL).
Cancer Risk Evaluation Guides (CREGs) are estimated contaminant concentrations thatwould be expected to cause no more than one additional excess cancer in one million personsexposed over a lifetime. CREGs are calculated from EPA's cancer slope factors (CSFs).
Remedial Media Evaluation Guides (RMEGs) are estimated contaminant concentrations ina media where non-carcinogenic health effects are unlikely. The RMEG is derived fromEPA's reference dose (RfD).
Maximum Contaminant Levels (MCLs) are enforceable drinking water regulationsestablished by EPA under the Safe Drinking Water Act that are protective of human healthto the extent feasible both technologically and economically. The MCL assumes exposureover a 70-year lifetime and ingestion of 2 liters of water per day.
EPA Action Levels (ALs) are estimated contaminant concentrations in water at whichadditional evaluation is needed to determine if action is required to eliminate or reduceexposure.
Lifetime Health Advisories (LTHAs) are derived by EPA from a drinking water equivalentlevel below which no adverse noncancer health effects are expected to occur over a 70-yearlifetime.
Premilinary Remediation Goals (PRGs) are the estimated contaminant concentrations inwhich no chance exists for carcinogenic or noncarcinogenic health effects. The PRGs used inthis public health assessment were derived using provisional reference doses or cancer slopefactors calculated by toxicologists of EPA's Region 9.
Evaluation of Public Health Implications
The next step is to take those contaminants that are above the CVs and further identify whichchemicals and exposure situations are likely to be a health hazard. Child and adult exposure dosesare calculated for the site-specific exposure scenario, using our assumptions of who goes on the siteand how often they contact the site contaminants. The exposure dose is the amount of a contaminantthat gets into a person's body. Following is a brief explanation of how we calculated the estimatedexposure doses for the site.
Exposure doses for groundwater ingestion were calculated in the following manner. The maximum concentration for a groundwater contaminant, in milligrams per liter (mg/L), was multiplied by the groundwater ingestion rate for adults, 2 liters/day, or children, 1 liter/day. The multiplication product was divided by the average weight for an adult (70 kilograms (kg)), or for a 2-year-old child (13.3 kg). The resulting dose, in units of milligrams per kilogram per day (mg/kg/day), was then multiplied by a factor of 350/365, because the exposure was assumed to occur 350 days a year.
Exposure doses for ingestion of contaminants from site soil were calculated using the maximum concentration measured in the soil, in milligrams per kilogram (mg/kg), or parts per million (ppm), multiplied by the soil ingestion rate for adults (0.0001 kg/day) or children (0.0002 kg/day). The multiplication product was divided by the average weight for an adult (70 kg) or a 2-year old child (13.3 kg). The resulting dose was then multiplied by a factor of 350/365, because the exposure was assumed to occur 350 days a year. For chronic exposures to arsenic and lead, the estimated 95th percentile of the data was also used as a high-end estimate of the average concentration.
Surface Water Ingestion
Exposure doses for surface water ingestion were calculated using the maximum concentration for a surface water contaminant, in milligrams per liter (mg/L), multiplied by an incidental surface water ingestion rate of 0.02 liter/day for adults or 0.01 liter/day for children. These ingestion rates are 1/100th of the EPA default drinking water rates. The multiplication product was divided by the average weight for an adult (70 kg) or for a 2-year old child (13.3 kg). The resulting dose was then multiplied by a factor of 350/365, because the exposure was assumed to occur 350 days a year.
Exposure doses for ingestion of contaminants from the sediment were calculated using the maximum concentration measured in the sediment, in mg/kg (or ppm), multiplied by 1/10th of the soil ingestion rate, 0.00001 kg/day for adults or 0.00002 kg/day for children. The multiplication product was divided by the average weight for an adult (70 kg) or for a 2-year old child (13.3 kg). The resulting dose was then multiplied by a factor of 350/365, because the exposure was assumed to occur 350 days a year.
Noncancer Health Effects
The calculated exposure doses are then compared to an appropriate health guideline for thatchemical. Health guideline values are considered safe doses; that is, health effects are unlikely belowthis level. The health guideline value is based on valid toxicologic studies for a chemical, withappropriate safety factors built-in to account for human variation, animal-to-human differences,and/or the use of the lowest adverse effect level. For noncancer health effects, the following healthguideline values are used.
Minimal Risk Level (MRLs) - developed by ATSDR
An estimate of daily human exposure - by a specified route and length of time - to a dose of chemical that is likely to be without a measurable risk of adverse, noncancer health effects. An MRL is not a predictor of adverse health effects. A list of MRLs for various contaminants can be found at http://www.atsdr.cdc.gov/mrls.html.
Reference Dose (RfD) - developed by EPA
An estimate, with safety factors built in, of the daily life-time (70 years) exposure of human populations to a possible contaminant that is not likely to cause noncancer health effects. A listing of RfDs can be found at http://www.epa.gov/iris/ .
If the estimated exposure dose for a specific chemical is less than the health guideline value for thechemical, then the exposure is unlikely to cause noncancer health effects in that specific situation. Ifthe exposure dose for a specific chemical is greater than the health guideline, then the exposure doseis compared to known toxicological values for that chemical and is discussed in more detail in thepublic health assessment. These toxicological values are doses derived from human and animalstudies, which are summarized in the series of toxicological profiles published by ATSDR. The basisfor deciding whether adverse health effects are likely or not at a specific site is a direct comparisonof data on site-specific exposure and doses with exposures and doses derived in human and animalstudies and which are known to cause adverse health effects.
Calculation of Cancer Risk
The estimated risk of developing cancer from exposure to the contaminants found at the BarberOrchard site was calculated by multiplying the site-specific adult exposure dose by EPA'scorresponding cancer slope factor (CSF). CSFs can be found at http://www.epa.gov/iris/ ). For the airpathway, the maximum air concentration of a contaminant was multiplied by the correspondingCSF. The result provides an estimate of the maximum increase in risk of developing cancer after 70years of exposure to that contaminant.
The actual risk of cancer is probably lower than the calculated number. The method used tocalculate the CSF assumes that high-dose animal data can be used to estimate the risk for low doseexposures in humans. The method also assumes that there is no safe level for exposure. Littleexperimental evidence exists to confirm or refute those two assumptions. Lastly, the methodcomputes the 95% upper bound for the risk, rather than the average risk, which suggests that thecancer risk is actually lower, perhaps by several orders of magnitude.(5)
Because of uncertainties involved in estimating cancer risk, ATSDR employs a weight-of-evidenceapproach in evaluating all relevant data(6). Therefore, the carcinogenic risk is described in words(qualitatively) rather than giving a numerical risk estimate only. The numerical risk estimate mustbe considered in the context of the variables and assumptions involved in their derivation and in thebroader context of biomedical opinion, host factors, and actual exposure conditions. The actualparameters of environmental exposures must be given careful consideration in evaluating theassumptions and variables relating to both toxicity and exposure.
|SOURCE FOR ALL PATHWAYS: Pesticides from Former Orchard Operations|
|PATHWAYNAME||ENVIRONMENTALMEDIA & TRANSPORTMECHANISMS||POINT OFEXPOSURE||ROUTE OFEXPOSURE||EXPOSUREPOPULATION||TIME||Complete?|
|Well water||Infiltration to groundwater||Groundwater wellssupplying drinkingwater taps||Ingestion, inhalation,dermal exposure||Residents or visitorsto site||Past,Present,Future||Y|
|Soil||Underground piping systemleaking in soil; Settling of sprayedpesticides on soil; Spills||Residential yards||Incidental ingestion,inhalation, dermalexposure||Residents or visitorsto site||Past,Present,Future||Y|
|Air / Dust||Fugitive dust released byconstruction and remediationactivities||Residential yards||Inhalation, dermalexposure||Residents or visitorsto site, nearbyresidents||Past,Present,Future||Y|
|Biota (Corn)||Uptake of contaminants from soiland/or groundwater into corn||Meal prepared usingcorn grown on site||Ingestion||Residents or otherconsumers||Past,Present,Future||Y|
|Surface water||Surface water runoff overcontaminated soil to streams;groundwater seepage||Along streams,ponds||Incidental ingestion,inhalation, dermalexposure||Residents or visitorsto site||Past,Present,Future||Y|
|Sediments||Deposition from surface waterrunoff into and alongside streams||Along streams,ponds||Incidental ingestion,dermal exposure||Residents or visitorsto site||Past,Present,Future||Y|
|Air /Volatilization||Volatilization of contaminants||Residential yards;water from privatewells||Inhalation, dermalexposure||Residents or visitorsto site, nearbyresidents||Past,Present,Future||N|
- How a chemical enters a person's blood after the chemical has been swallowed, has come into contact with the skin, or has been breathed in.
- Acute Exposure:
- Contact with a chemical that happens once or only for a limited period of time. ATSDR defines acute exposures as those that might last up to 14 days.
- Additive Effect:
- A response to a chemical mixture, or combination of substances, that might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
- Adverse Health Effect:
- A change in body function or the structures of cells that can lead to disease or health problems.
- Antagonistic Effect:
- A response to a mixture of chemicals or combination of substances that is less than might be expected if the known effects of individual chemicals, seen at specific doses, were added together.
- The Agency for Toxic Substances and Disease Registry. ATSDR is a federal health agency in Atlanta, Georgia that deals with hazardous substance and waste site issues. ATSDR gives people information about harmful chemicals in their environment and tells people how to protect themselves from coming into contact with chemicals.
- Background Level:
- An average or expected amount of a chemical in a specific environment. Or, amounts of chemicals that occur naturally in a specific-environment.
- See Relative Bioavailability
- Used in public health, things that humans would eat - including animals, fish and plants.
- A group of diseases which occur when cells in the body become abnormal and grow, or multiply, out of control
- Cancer Slope Factor:
- The slope of the dose-response curve for cancer. Multiplying the CSF by the dose gives a prediction of excess cancer risk for a contaminant.
- Any substance shown to cause tumors or cancer in experimental studies.
- Chronic Exposure:
- A contact with a substance or chemical that happens over a long period of time. ATSDR considers exposures of more than one year to be chronic.
- Completed Exposure Pathway:
- See Exposure Pathway.
- Community Assistance Panel (CAP):
- A group of people from the community and health and environmental agencies who work together on issues and problems at hazardous waste sites.
- Comparison Value (CV):
- Concentrations or the amount of substances in air, water, food, and soil that are unlikely, upon exposure, to cause adverse health effects. Comparison values are used by health assessors to select which substances and environmental media (air, water, food and soil) need additional evaluation while health concerns or effects are investigated.
- Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA):
- CERCLA was put into place in 1980. It is also known as Superfund. This act concerns releases of hazardous substances into the environment, and the cleanup of these substances and hazardous waste sites. ATSDR was created by this act and is responsible for looking into the health issues related to hazardous waste sites.
- How much or the amount of a substance present in a certain amount of soil, water, air, or food.
- See Environmental Contaminant.
- Delayed Health Effect:
- A disease or injury that happens as a result of exposures that may have occurred far in the past.
- Dermal Contact:
- A chemical getting onto your skin. (see Route of Exposure).
- The amount of a substance to which a person may be exposed, usually on a daily basis. Dose is often explained as "amount of substance(s) per body weight per day".
- Dose / Response:
- The relationship between the amount of exposure (dose) and the change in body function or health that result.
- The amount of time (days, months, years) that a person is exposed to a chemical.
- Environmental Contaminant:
- A substance (chemical) that gets into a system (person, animal, or the environment) in amounts higher than that found in Background Level, or what would be expected.
- Environmental Media:
- Usually refers to the air, water, and soil in which chemical of interest are found. Sometimes refers to the plants and animals that are eaten by humans. Environmental Media is the second part of an Exposure Pathway.
- U.S. Environmental Protection Agency (EPA):
- The federal agency that develops and enforces environmental laws to protect the environment and the public's health.
- The study of the different factors that determine how often, in how many people, and in which people will disease occur.
- Coming into contact with a chemical substance.(For the three ways people can come in contact with substances, see Route of Exposure.)
- Exposure Assessment:
- The process of finding the ways people come in contact with chemicals, how often and how long they come in contact with chemicals, and the amounts of chemicals with which they come in contact.
- Exposure Pathway:
- A description of the way that a chemical moves from its source (where it began) to where and how people can come into contact with (or get exposed to) the chemical.
ATSDR defines an exposure pathway as having 5 parts:
- Source of Contamination,
- Environmental Media and Transport Mechanism,
- Point of Exposure,
- Route of Exposure; and,
- Receptor Population.
When all 5 parts of an exposure pathway are present, it is called a Completed Exposure Pathway. Each of these 5 terms is defined in this Glossary.
- How often a person is exposed to a chemical over time; for example, every day, once a week, twice a month.
- Hazardous Waste:
- Substances that have been released or thrown away into the environment and, under certain conditions, could be harmful to people who come into contact with them.
- Health Effect:
- ATSDR deals only with Adverse Health Effects (see definition in this Glossary).
- Indeterminate Public Health Hazard:
- The category is used in Public Health Assessment documents for sites where important information is lacking (missing or has not yet been gathered) about site-related chemical exposures.
- Swallowing something, as in eating or drinking. It is a way a chemical can enter your body (See Route of Exposure).
- Breathing. It is a way a chemical can enter your body (See Route of Exposure).
- Lowest Observed Adverse Effect Level. The lowest dose of a chemical in a study, or group of studies, that has caused harmful health effects in people or animals.
- See Cancer.
- Minimal Risk Level. An estimate of daily human exposure - by a specified route and length of time -- to a dose of chemical that is likely to be without a measurable risk of adverse, noncancerous effects. An MRL should not be used as a predictor of adverse health effects.
- The National Priorities List. (Which is part of Superfund.) A list kept by the U.S. Environmental Protection Agency (EPA) of the most serious, uncontrolled or abandoned hazardous waste sites in the country. An NPL site needs to be cleaned up or is being looked at to see if people can be exposed to chemicals from the site.
- No Observed Adverse Effect Level. The highest dose of a chemical in a study, or group of studies, that did not cause harmful health effects in people or animals.
- No Apparent Public Health Hazard:
- The category is used in ATSDR's Public Health Assessment documents for sites where exposure to site-related chemicals may have occurred in the past or is still occurring but the exposures are not at levels expected to cause adverse health effects.
- No Public Health Hazard:
- The category is used in ATSDR's Public Health Assessment documents for sites where there is evidence of an absence of exposure to site-related chemicals.
- Public Health Assessment. A report or document that looks at chemicals at a hazardous waste site and tells if people could be harmed from coming into contact with those chemicals. The PHA also tells if possible further public health actions are needed.
- A line or column of air or water containing chemicals moving from the source to areas further away. A plume can be a column or clouds of smoke from a chimney or contaminated underground water sources or contaminated surface water (such as lakes, ponds and streams).
- Point of Exposure:
- The place where someone can come into contact with a contaminated environmental medium (air, water, food or soil). For examples:
the area of a playground that has contaminated dirt, a contaminated spring used for drinking water, the location where fruits or vegetables are grown in contaminated soil, or the backyard area where someone might breathe contaminated air.
- A group of people living in a certain area; or the number of people in a certain area.
- Potentially Responsible Party. A company, government or person that is responsible for causing the pollution at a hazardous waste site. PRP's are expected to help pay for the clean up of a site.
- Public Health Assessment(s):
- See PHA.
- Public Health Hazard:
- The category is used in PHAs for sites that have certain physical features or evidence of chronic, site-related chemical exposure that could result in adverse health effects.
- Public Health Hazard Criteria:
- PHA categories given to a site which tell whether people could be harmed by conditions present at the site. Each are defined in the Glossary. The categories are:
- Urgent Public Health Hazard
- Public Health Hazard
- Indeterminate Public Health Hazard
- No Apparent Public Health Hazard
- No Public Health Hazard
- Receptor Population:
- People who live or work in the path of one or more chemicals, and who could come into contact with them (See Exposure Pathway).
- Reference Dose (RfD):
- An estimate, with safety factors (see safety factor) built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause harm to the person.
- Relative Bioavailability:
- The amount of a compound that can be absorbed from a particular medium (such as soil) compared to the amount absorbed from a reference material (such as water). Expressed in percentage form.
- Route of Exposure:
- The way a chemical can get into a person's body. There are three exposure routes:
- breathing (also called inhalation),
- eating or drinking (also called ingestion), and
- or getting something on the skin (also called dermal contact).
- Safety Factor:
- Also called Uncertainty Factor. When scientists don't have enough information to decide if an exposure will cause harm to people, they use "safety factors" and formulas in place of the information that is not known. These factors and formulas can help determine the amount of a chemical that is not likely to cause harm to people.
- The Superfund Amendments and Reauthorization Act in 1986 amended CERCLA and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from chemical exposures at hazardous waste sites.
- Sample Size:
- The number of people that are needed for a health study.
- A smallnumber of people chosen from a larger population (See Population).
- Source (of Contamination):
- The place where a chemical comes from, such as a landfill, pond, creek, incinerator, tank, or drum. Contaminant source is the first part of an Exposure Pathway.
- Special Populations:
- People who may be more sensitive to chemical exposures because of certain factors such as age, a disease they already have, occupation, sex, or certain behaviors (like cigarette smoking). Children, pregnant women, and older people are often considered special populations.
- A branch of the math process of collecting, looking at, and summarizing data or information.
- Superfund Site:
- See NPL.
- A way to collect information or data from a group of people (population). Surveys can be done by phone, mail, or in person. ATSDR cannot do surveys of more than nine people without approval from the U.S. Department of Health and Human Services.
- Synergistic effect:
- A health effect from an exposure to more than one chemical, where one of the chemicals worsens the effect of another chemical. The combined effect of the chemicals acting together are greater than the effects of the chemicals acting by themselves.
- Harmful. Any substance or chemical can be toxic at a certain dose (amount). The dose is what determines the potential harm of a chemical and whether it would cause someone to get sick.
- The study of the harmful effects of chemicals on humans or animals.
- Abnormal growth of tissue or cells that have formed a lump or mass.
- Uncertainty Factor:
- See Safety Factor.
- Urgent Public Health Hazard:
- This category is used in ATSDR's Public Health Assessment documents for sites that have certain physical features or evidence of short-term (less than 1 year), site-related chemical exposure that could result in adverse health effects and require quick intervention to stop people from being exposed.
1. Based on discussions with Jon Bornholm, U.S. Environmental Protection Agency.
2. Based on discussions with Jon Bornholm, U.S. Environmental Protection Agency.
3. Based on discussions with Mr. Dan Townsend of McGill Associates, contractor for the city of Waynesville.
4. Based on a March 6, 2002 conversation with Dr. David Butcher, Professor of Chemistry at Western Carolina University.
5. Environmental Protection Agency (EPA), Office of Emergency and Remedial Response. Risk Assessment Guidance for Superfund, Volume 1, Human Health Evaluation Manual. December 1989.
6. Agency for Toxic Substances and Disease Registry (ATSDR). Cancer Policy Framework. January 1993.