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Screening Process

In evaluating these data, ATSDR used comparison values (CVs) to determine whichchemicals to examine more closely. CVs are the contaminant concentrations foundin a specific media (soil or water) and are used to select contaminants for furtherevaluation. CVs incorporate assumptions of daily exposure to the chemical and astandard amount of water and soil that someone may inhale or ingest each day.

CVs are set at a concentration below which no known or anticipated adverse humanhealth effects are expected to occur. Different CVs are developed for cancer andnoncancer health effects. Noncancer levels are based on valid toxicological studiesfor a chemical, with appropriate safety factors included, and the assumption thatsmall children (22 pounds) and adults are exposed every day. Cancer levels are themedia concentrations at which there could be a one in a million excess cancer riskfor an adult eating contaminated soil or drinking contaminated water every day for70 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 healtheffects 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 is derived from the Agency for Toxic Substances and DiseaseRegistry's (ATSDR) minimal risk level (MRL).

Reference dose Media Evaluation Guides (RMEGs) are estimated contaminant concentrations in a media where non-carcinogenic health effects are unlikely.The RMEG is derived from the Environmental Protection Agency's (EPA's) reference dose(RfD).

Cancer Risk Evaluation Guides (CREGs) are estimated contaminantconcentrations that would be expected to cause no more than one additionalexcess cancer in one million persons exposed over a lifetime. CREGs arecalculated from EPA's cancer slope factors (CSFs).

EPA Soil Screening Levels (SSLs) are estimated contaminant concentrations insoil at which additional evaluation is needed to determine if action is required to eliminate or reduce exposure.

Evaluation of Public Health Implications

The next step is to take those contaminants that are above the CVs and further identifywhich chemicals and exposure situations are likely to be a health hazard.

Estimation of Exposure Dose

Child and adult exposure doses are calculated assuming a worst-case scenario whereexposure occurs every day. The exposure dose is the amount of a contaminant thatgets into a person's body.

The ATSDR exposure dose formula is:

ed = c * ir * ef * af / bw


ed = exposure dose; c = concentration in media of interest; ir = ingestion rate; ef = exposure factor; af = absorption factor; bw = body weight

Noncancer Health Effects

The calculated exposure doses are then compared to an appropriate health guidelinefor that chemical. Health guideline values are considered safe doses; that is, healtheffects are unlikely below this level. The health guideline value is based on validtoxicological studies for a chemical, with appropriate safety factors built in toaccount for human variation, animal-to-human differences, and/or the use of thelowest 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, noncancerous effects. An MRL should not be used as a predictor of adverse health effects. A list of MRLs can be found at The MRL for a chemical is described in detail in the ATSDR Toxicological Profile for that chemical

Reference Dose (RfD) - developed by EPA
An estimate, with safety factors built in, of the daily, life-time exposure of human populations to a possible hazard that is not likely to cause noncancerous health effects. The RfDs can be found in the Integrated Risk Information System (IRIS) at .

Provisional Reference Dose (RfD) - developed by EPA's National Center for Environmental Assessment (NCEA)
Provisional RfDs are established to identify clean-up levels at NPL sites for chemicals for which the toxicological data do not meet the standards used for RfDs and MRLs. Therefore, there is more uncertainty in the number identified. Provisional RfDs can be found at or .

If the worst-case exposure dose for a chemical is less than the health guideline value,then the exposure is unlikely to cause a non-carcinogenic health affect in anysituation. If exposure dose for the worst-case exposure scenario is greater thanthe health guideline, child and adult exposure doses are re-calculated using site-specific estimates of who goes on the site and how often they contact the sitecontaminants. If the site-specific exposure dose for a chemical is less than thehealth guideline value, then the exposure is unlikely to cause a non-carcinogenichealth affect in that specific situation.

When the health guideline is exceeded, the site-specific exposure dose is comparedto known toxicological values for that chemical starting with the no observed andlowest observed adverse effect levels (NOAEL and LOAEL) used to derive theMRL or RfD. These toxicological values are doses derived from human and animalstudies which are summarized in the ATSDR Toxicological Profile for thatchemical or in EPA's IRIS.

The first step in this comparison to toxicological values is the calculation of a"margin of effect" or MOE by dividing the LOAEL and/or NOAEL by the site-specific exposure dose. In general, when the MOE is greater than 1,000, harmfuleffects are not expected. When the MOE ranges from approximately 100 - 1000,harmful effects are unlikely but further toxicological evaluation is done to confirmthis. If the MOE is between 10 to 100, harmful effects are more likely, but furthertoxicological evaluation is needed. When the MOE is 10 or less, it is usuallyconcluded that health effects are likely.

Interpretation of the MOE, however, is somewhat subjective and dependent on ahost of toxicological factors. Further evaluation consists of a careful comparison ofthe site-specific exposure doses and circumstances to the epidemiological andexperimental data on the chemical. The underlying premise in this comparison ishow well the available data might predict human health effects in the past or on-going exposure scenarios.

Calculation of Risk of Carcinogenic Effects

The estimated risk of developing cancer from exposure to the contaminants wascalculated by multiplying the site-specific adult exposure dose by EPA'scorresponding Cancer Slope Factor (which can be found at ).The results estimate the maximum increase in risk of developing cancer after 70years of exposure to the contaminant.

The actual risk of cancer is probably lower than the calculated number. The methodused to calculate EPA's Cancer Slope Factor assumes that high-dose animal datacan be used to estimate the risk for low dose exposures in humans. The method alsoassumes that there is no safe level for exposure. Little experimental evidence existsto confirm or refute those two assumptions. Lastly, the method computes the 95%upper bound for the risk, rather than the average risk, suggesting that the cancerrisk is actually lower, perhaps by several orders of magnitude [18].

ATSDR considers a maximum additional lifetime cancer risk of greater than 1 in10,000 (1 × 10-4) to potentially be a public health problem and thus further evaluation is needed[19]. Cancer risks less than 1 in 10,000 are not usually considered a healthconcern.

ATSDR employs a weight-of-evidence approach in further evaluating carcinogenic risk[19]. The numerical risk estimate is considered in the context of the variables andassumptions involved in their derivation and in the broader context of biomedicalopinion, host factors, and actual exposure conditions.

Decision Points

Besides the results of the toxicological evaluation, identifying a specific exposurescenario as a health hazard includes consideration of whether the exposure isongoing and needs to be stopped or avoided. When those conditions are met,ATSDR takes a conservative (health-protective) approach where the decision pointis near the health guideline. Factors such as background chemical levels and theuncertainty factor used in deriving the health guideline may play a mitigating rolein this decision. The decision point will always be greater than the naturalbackground level for an area. The larger the uncertainty factor the greaterflexibility there is in the decision point.

When the exposure scenario being evaluated occurred in the past, the question beinganswered now becomes whether those exposed likely did or will become sick. In thissituation, the decision point tends to be closer to the lowest observed adverse healtheffects rather than the health guideline.


Table B1.

Completed Exposure Pathways for the Eastland Woolen Mill (EWM) Site - Source: Former Eastland Woolen Mill
Pathway Name Media Point of Exposure Route of Exposure Exposed Population Exposure Period Contaminants of Concern Notes
Private Well Groundwater Residences & businesses in Corinna Ingestion, inhalation, skin contact Residents, employees, & customers Past Chlorinated benzenes, benzene Everyone in contaminant plume uses municipal water system for drinking water.
Soil Soil Former EWM site, old dump Ingestion, inhalation, skin contact Former EWM workers, trespassers, hunters and all terrain vehicle riders at old dump EWM Site: Past; Old dump: Past, Present, Future Chlorinated benzenes , other volatile organic compounds (VOCs) pesticides, heavy metals Contaminated surface soils have been removed or covered at EWM site.
Past Mill Work Indoor Air, direct contact with chemicals Textile finishing process areas (vats, basement of old building) Ingestion, inhalation, skin contact Workers Past Chlorinated benzenes, coal-tar derivative dyes, other process chemicals Little information exists about exact chemicals used.
Sediment/ Floodplain Soil Sediment in riverbed and floodplain Along or in EBSR Ingestion, inhalation, skin contact Fishers & others who contact sediment Past, Present, Future Chlorinated benzenes, polyaromatic hydrocarbons, dieldrin, and several metals  
Surface Water River water In the EBSR Ingestion Anglers and others with contact with the water Past Chlorinated benzenes and other VOCs  
Fish Fish Places where fish are eaten Ingestion Persons who eat fish from the EBSR Past, Present, Future Mercury & dioxins Contaminant levels above comparison values but not site-related
Air Ambient Air Areas in, close to and downwind of the mill Inhalation Workers, nearby residents and business employees Past Chlorinated benzenes and other VOCs Exposures to VOCs probable for those working in or living near the mill when the mill was in operation; no data are available on this pathway


Summary of Findings

The Agency for Toxic Substances and Disease Registry (ATSDR) requested that theMaine Bureau of Health's Cancer Registry investigate the cancer incidence rate inCorinna, Maine. The town of Corinna was the site of the former Eastland WoolenMill.

The investigation reviewed individual types of cancer to determine if there was a higherrate in Corinna than in the state of Maine. Cancer data from 1983 through 1998 wasincluded in the analysis. The results indicate that the cancer rates in Corinna were notstatistically significantly higher than the rates in Maine.


The Bureau of Health's Maine Cancer Registry provided the cancer incidence rates inthe town of Corinna from 1983 through 1998. The Bureau of Health's Office ofData, Research, and Vital Statistics provided 1983-1998 population figures for thistown.

Several cancer sites were evaluated to determine if there were statistically moreobserved cases in Corinna than expected. The expected number of cases in Corinnawas estimated using the standardized morbidity ratio. The 1983-1998, age- and site-specific rates in Maine were multiplied by the population of Corinna during the sametime period.

Statistical Analysis

For cancer sites with more than 15 cases occurring in Corinna from 1983 to 1998, theage-adjusted incidence rate was computed and compared to the Maine rate. Statistical significance was determined by whether or not the 95% confidence intervalfor Corinna included the Maine age-adjusted rate. If the Corinna confidence intervaldid include the Maine rate, the number of cases in Corinna would not be statisticallydifferent from Maine. If the confidence interval did not include the Maine rate, thenthe cancer rate in Corinna would be statistically significantly lower or higher than theMaine rate.

For cancer sites with 15 or fewer cases in Corinna from 1983 to 1998, the statisticalsignificance was determined by comparing the observed cases in Corinna with theexpected cases in Corinna under the Poisson distribution. The Poisson distributionis an appropriate test of significance when the disease occurrence is rare (a smallnumber of cases relative to the size of the population). A conservative p-value(p<0.001) was used based on the Maine Cancer Registry's Cancer Inquiry Protocol,the nature of the Poisson analysis, and because multiple comparisons were done onthe data. The formula for calculating the p-value under the Poisson distribution isas follows:

p equals e sup -lambda times lambda sup n divided by n! where p = probability of outcome (must be < .001)
e = »constant 2.718
l = expected number of cases (based on the standardized morbidity ratio)
n = actual number of cases reported


The age-adjusted incidence rates and 95% confidence intervals (p-value = 0.05) werecalculated for cancer sites with more than 15 cases (Table 1). Because the confidenceintervals in Corinna include the Maine rates for each cancer site, the analysisindicates that none of the rates are statistically higher or lower in Corinna than inMaine.

The confidence intervals are wide in Corinna due to a small number of observed cases(Table 2). Calculating 99.9% confidence interval to match the p-value of 0.001 in thePoisson analysis would cause the confidence interval for Corinna to become even widerand more likely to include the Maine age-adjusted rate.

For cancers with 15 or fewer cases during the 1983-1998 time period, the Poisson methodwas used to determine if the observed number of cases in Corinna was higher thanexpected (Table 3). For these cancer sites, none of the statistical tests resulted in a p-value less than or equal to 0.001, indicating that there were not statistically significantlymore or less observed cases in Corinna than expected. Table 3 shows the differencebetween the observed (X) and expected (Y) cases in Corinna and the probability ofobserving X or more cases in Corinna when the expected number of cases is Y.


The age-adjusted overall cancer incidence rate in Maine from 1983 to1998 was 365.6per 100,000. Corinna had an overall cancer incidence rate of 365.7, which was notsignificantly different from the Maine rate. None of the common cancer sites(lung, female breast, prostate, and colorectal) were significantly higher in Corinnathan in Maine. Corinna had a slightly higher rate of lung and bronchus cancer,65.6 per 100,000, than the state, 61.3 per 100,000, but this difference was notstatistically significant. The age-adjusted rates of prostate, colorectal, and femalebreast cancer in Corinna were lower than the rates in Maine, although thedifferences were not statistically significant. Analysis of the less common cancersites did not reveal any statistically significant excess in the number of observedversus expected cases in Corinna for this time period.

Table 1:

Age-Adjusted Cancer Incidence Rates for the Most Common Cancer Sites, 1983-1998
Cancer Site Geographic Location Age-Adjusted Rate Lower 95% Confidence Interval Upper 95% Confidence Interval
Colon & Rectum Maine 49.9 49.0 50.9
  Corinna 45.5 27.9 72.7


Lung & Bronchus Maine 61.3 60.3 62.4
  Corinna 65.6 43.4 97.8


Female Breast Maine 99.4 97.6 101.2
  Corinna 86.6 50.4 144.3


Prostate Maine 98.6 96.7 100.5
  Corinna 95.7 57.0 156.5


All Cancers Maine 365.6 363.1 368.1
  Corinna 365.7 310.1 430.8

Note: Rates are per 100,000 and age-adjusted to the 1970 U.S. Standard

Table 2.

Common Cancer Case Count in Corinna, 1983-1998
Cancer Site Count
Lung & Bronchus 28
Prostate 19
Colon & Rectum 21
Breast (Female) 18
All Cancers 158

Table 3.

Cancer Site Analysis for Corinna vs. Maine, 1983-1998
Cancer Site Observed -Expected (X - Y) Poisson p-value
Oral Cavity & Pharynx 4.7 0.02
Non-Hodgkin's Lymphoma 3.5 0.05
Brain & CNS 2.5 0.07
Esophagus 2.3 0.06
Melanoma 1.6 0.13
Multiple Myeloma 1.4 0.14
Testis 1.2 0.14
Larynx 0.9 0.19
Bones & Connective Tissue 0.8 0.22
Ureter 0.7 0.22
Thyroid 0.7 0.23
Anus 0.6 0.27
Gallbladder 0.6 0.27
Vulva 0.5 0.30
Stomach 0.3 0.22
Liver 0.3 0.35
Cervix 0.1 0.26
Pancreas -0.3 0.22
Ovary -1.0 0.22
Kidney & Renal Pelvis -1.0 0.20
Uterine -1.6 0.16
Leukemia -2.5 0.11
Urinary Bladder -5.7 0.02


This public health assessment (PHA) was available for public review and comment atthe Stewart Free Library and the Town Manager's office at 8 Levi Stewart Drive inCorinna, Maine and the EPA New England Records Center at One Congress Streetin Boston, Mass. from September 17, 2003 to December 1, 2003. The document wasalso available for viewing or downloading from the Corinna Web site: .

The public comment period was announced in local newspapers. The public healthassessment was sent to members of the executive committee of SCCE; the CorinnaTown Manager; and staff in the Maine Department of Environmental Protection,Maine Bureau of Health, Maine Cancer Registry, and the U.S. EnvironmentalProtection Agency (EPA).

General Comments

  1. The overall presentation of information and format is very good. The documentis easy to read and generally provided the information that ATSDR said itwould.
  2. Response: Thanks!

  3. ATSDR has incorporated SCCE's previous comments in a number of places in thetext.
  4. Response: ATSDR found SCCE's comments very helpful in focusing andclarifying the results of this public health assessment.

  5. I did not find a discussion or reference to latency periods for the various healtheffects (primarily cancer) in the text. Would health effects be expected to occur inthe time periods evaluated? Perhaps it is not possible to make this determination,but a discussion might be informative to the reader.
  6. Response: A brief mention of this issue has been inserted into the Community Health Concerns section on page 25.

  7. The text should contain a brief discussion of what would be reasonable steps for aperson to take if he/she were concerned about potential past exposures. (i.e., seea physician and describe types of chemical exposure, time periods, routes ofexposure, etc.)
  8. Response: This information is now briefly mentioned on page 25.

  9. Can the document provide a discussion of the difference between "relativeincreased risks" of cancer versus statements about rates of cancer. How do theyrelate or not relate? Some individuals were confused about various "rates ofcancer" or possible rates of cancer that were discussed in the meeting or text ascompared to statements about an increased risk of cancer greater than 10-4.
  10. Response: A brief discussion of this issue can now be found on page 23.

  11. There is strong support for a follow-up cancer evaluation as discussed in thePublic Meeting.
  12. Response: A recommendation that MCR do such a follow-up evaluation has been included in this public health assessment.

  13. Although risks and potential health effects were discussed for each individualexposure routes, it did not appear that a discussion of potential cumulative effectswas discussed.
  14. Response: A brief discussion of cumulative effects is in the Multiple Exposure Pathways section at the bottom of page 21.

Specific Comments

  1. Page 7, bullet items. Soil treatment will be completed in October 2003 according to Ed Hathaway of EPA.
  2. Response: This bullet has been revised to reflect this.

  3. Page 11, last paragraph. " wells close to THE...", use lower case "the".
  4. Response: This change has been made.

  5. Page 11, last paragraph. Delete "in several directions, including" and add
    "primarily to".
  6. Response: This change has been made.

  7. Page 12, Table 1. Laboratory analyses for benzene typically have a detection limitof 1 part per billion (ppb). As a result, the "ND" is above the Comparison Value(CV) of 0.6 ppb. Therefore, a benzene concentration below the "ND" may bepresent and still be above the CV. I doubt that it will make a material differencein the outcome, but it may have a minor affect on the statistics or the # ofexceedences.
  8. Response: Although detection limits may vary depending on the sample, most ofthe detection limits reported in the groundwater data ATSDR received were 0.5ppb. ATSDR did not count nondetects as exceedances even if the detection limitwas higher than the CV.

  9. Page 12, Table 1. The data for 1,2,3-trichlolrobenzene indicates that 117exceedences of the CV (40 ppb) occurred out of 117 samples. Yet the range ofconcentrations is from 15 to 1,750 ppb. This suggests that a number of samplesmay have been below the CV of 40 ppb and that not all samples exceeded the CVvalue.
  10. Response: Thank you for pointing out this error. We have reexamined this dataand found that there were 42 exceedances of the 40 ppb CV out of 108 samples.The data we have available also indicates that the range of values for thiscontaminant is from nondetect to 565 ppb. Table 1 has been corrected and theconclusion that no health effects are likely from exposure to 1,2,3-trichlorobenzeneremains the same.

  11. Page 12, last paragraph. Under the discussion of Public Health Implications,reference is made to the "highest mean concentration for a contaminant". Thehighest mean concentrations (actual values) for children and adults are not stated inthe text or tables as far as I can tell. Adding the value would be helpful to the reader.Would the conclusions change if the highest (or higher than the mean) value was usedin the analysis? Although mean values are used to assess overall populations, anumber of workers may have been exposed to higher than the mean value for a longperiod.
  12. Response: The mean concentrations referred to in the text are averages over time fora specific well. Anyone drinking water from a well in the area would be exposed, onaverage, to this mean concentration over time. Because a person could have drunkout of one specific well over the entire time period, we used the highest meanconcentration measured in any of the wells to estimate doses in a "worst-case"scenario. This would apply to workers or residents who were exposed tocontaminants in drinking water near the site, although workers' exposure throughdrinking water would likely be lower since they only spent a fraction of their time atthe site drinking from potentially impacted wells.

    The value used in the exposure dose calculations is the highest mean over time of allthe individual wells sampled and is the high end of the range shown in the secondcolumn of Table 1. We have changed the heading of column 2 to: "Range of time-averaged concentrations in ppb" to clarify this issue.

  13. It seems unusual to me that the discussions of health effects shows that many of thedoses received by a child or worker were assumed to be 10 to 100 times greater than"a reference dose generally considered to be safe". Yet ATSDR concludes that thesedoses are still 30 to 150 times less than doses shown to cause health effects. Thisimplies that the reference dose is many orders of magnitude lower than any of thestudies that indicate adverse health effects. Basically, what good are the referencedose standards if they have no real relation to adverse health effects?
  14. Response: Minimal risk levels (MRLs) and reference doses (RfDs) are defined asdoses of chemical where health effects will not occur or are very unlikely. They arethe basis for ATSDR's and EPA's decisions whether a specific chemical exposure is"safe" if the exposure dose for that chemical is less than the MRL or RfD.

  15. Page 13, Cancer Risk paragraph. This paragraph states that drinking the "maximumdetected concentration" would have increased a person's cancer risk by a moderateto high amount. Previous discussion uses the "highest mean concentration" as abasis for analysis. For consistency, the discussions should probably stick withwhatever value is selected.
  16. Response: "Maximum detected concentration" has been revised to "highest mean concentration".

  17. Page 13, last sentence. "No health effects...". This seems like an absolute statementwhen much of the previous discussion contains a degree of uncertainty. I think somequalification may be appropriate such as "As a result, adverse health effects areunlikely to occur from such use" or similar statement.
  18. Response: We concluded and continue to conclude that this statement is appropriate.

  19. Page 14, 2nd paragraph. I'm not sure if I'm reading the intent properly, but ATSDRstates that using subsurface contaminant concentrations in soil should provide a"conservative estimate" of past surface concentrations. The way I read this impliesthat ATSDR believes that surface concentrations of contaminants would have beenlower than subsurface concentrations. If surface releases (spills) of contaminantshad occurred in the past, surface soil concentrations could (probably would) besignificantly higher than the subsurface values found by EPA many years after spillshad ceased. As the contaminants get diluted, disperse through soil and attenuate asthey migrate downward, I would expect that subsurface soil concentrations would bemuch lower than surface soil, not the opposite. Therefore, the values would not be"conservative" with respect to possible exposure scenarios and health effects.
  20. Response: ATSDR analyzed past exposures in response to a request from thecommunity. Because so little information was available on past contaminant levelsand exposures, many assumptions based on professional judgment had to be made.The reader should be aware of the large degree of uncertainty in any of the dosecalculations and conclusions reached regarding past exposures at the site becauseof the impossibility of verifying the assumptions made.

    The rationale for using subsurface contaminant concentrations as a conservativeestimate of past surface soil concentrations is given in more detail here. Most of thecontaminants of concern are volatile contaminants; that is, they evaporate easilyand rather quickly in air. Before and during the cleanup, pockets of very high levelsof these contaminants were measured in several subsurface areas.

    These areas served as a continuing source of contaminants to the EBSR. ATSDR assumed that the subsurface contaminants would not evaporate or be naturally degraded to an appreciable extent, due to a lack of air and oxygen.

    ATSDR considered that the high levels of contaminants in the subsurface were aresult of many years of spills and disposal of contaminants onto the ground surfacewhich led to a buildup in the subsurface soil due to confining layers beneath. ATSDRassumed that at the time of any one spill, the concentrations of contaminants wouldbe high, but any contaminant that did not filter down into the subsurface would havequickly evaporated into the air, so that the long-term average surface soilconcentration would not be as high as the concentrations beneath the ground surface.

  21. I think largemouth (as in largemouth bass) is one word. It varies throughout thetext.
  22. Response: This change has been made. Thanks for bringing it to our attention.

  23. Page 22, end of 2nd paragraph in Evaluation of Health Outcome Data section. "...information on cancer for residents in the Corinna." Remove "the" from the sentence.
  24. Response: This change has been made.


The Agency for Toxic Substances and Disease Registry (ATSDR) is a federal publichealth agency with headquarters in Atlanta, Georgia, and 10 regional offices inthe United States. ATSDR's mission is to serve the public by using the bestscience, taking responsive public health actions, and providing trusted healthinformation to prevent harmful exposures and diseases related to toxicsubstances. ATSDR is not a regulatory agency, unlike the U.S. EnvironmentalProtection Agency (EPA), which is the federal agency that develops and enforcesenvironmental laws to protect the environment and human health. This glossarydefines words used by ATSDR in communications with the public. It is not acomplete dictionary of environmental health terms. If you have questions orcomments, call ATSDR's toll-free telephone number, 1-888-42-ATSDR (1-888-422-8737).

General Terms

The process of taking in. For a person or an animal, absorption is the process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs.

Occurring over a short time [compare with chronic].

Acute exposure :
Contact with a substance that occurs once or for only a short time (up to 14 days) [compare with intermediate duration exposure and chronic exposure].

Additive effect :
A biologic response to exposure to multiple substances that equals the sum of responses of all the individual substances added together [compare with antagonistic effect and synergistic effect].

Adverse health effect :
A change in body function or cell structure that might lead to disease or health problems

Aerobic :
Requiring oxygen [compare with anaerobic].

Ambient :
Surrounding (for example, ambient air).

Anaerobic :
Requiring the absence of oxygen [compare with aerobic].

Analyte :
A substance measured in the laboratory. A chemical for which a sample (such as water, air, or blood) is tested in a laboratory. For example, if the analyte is mercury, the laboratory test will determine the amount of mercury in the sample.

Analytic epidemiologic study :
A study that evaluates the association between exposure to hazardous substances and disease by testing scientific hypotheses.

Antagonistic effect :
A biologic response to exposure to multiple substances that is less than would be expected if the known effects of the individual substances were added together [compare with additive effect and synergistic effect].

Background level :
An average or expected amount of a substance or radioactive material in a specific environment, or typical amounts of substances that occur naturally in an environment.

Biodegradation :
Decomposition or breakdown of a substance through the action of microorganisms (such as bacteria or fungi) or other natural physical processes (such as sunlight).

Biologic indicators of exposure study :
A study that uses (a) biomedical testing or (b) the measurement of a substance [an analyte], its metabolite, or another marker of exposure in human body fluids or tissues to confirm human exposure to a hazardous substance [also see exposure investigation].

Biologic monitoring :
Measuring hazardous substances in biologic materials (such as blood, hair, urine, or breath) to determine whether exposure has occurred. A blood test for lead is an example of biologic monitoring.

Biologic uptake :
The transfer of substances from the environment to plants, animals, and humans.

Biomedical testing :
Testing of persons to find out whether a change in a body function might have occurred because of exposure to a hazardous substance.

Biota :
Plants and animals in an environment. Some of these plants and animals might be sources of food, clothing, or medicines for people.

Body burden :
The total amount of a substance in the body. Some substances build up in the body because they are stored in fat or bone or because they leave the body very slowly.

[see Community Assistance Panel.]

Cancer :
Any one of a group of diseases that occur when cells in the body become abnormal and grow or multiply out of control.

Cancer risk :
A theoretical risk for getting cancer if exposed to a substance every day for 70 years (a lifetime exposure). The true risk might be lower.

Carcinogen :
A substance that causes cancer.

Case study :
A medical or epidemiologic evaluation of one person or a small group of people to gather information about specific health conditions and past exposures.

Case-control study :
A study that compares exposures of people who have a disease or condition (cases) with people who do not have the disease or condition (controls). Exposures that are more common among the cases may be considered as possible risk factors for the disease.

CAS registry number :
A unique number assigned to a substance or mixture by the American Chemical Society Abstracts Service.

Central nervous system :
The part of the nervous system that consists of the brain and the spinal cord.

[see Comprehensive Environmental Response, Compensation, and Liability Act of 1980]

Chronic :
Occurring over a long time [compare with acute].

Chronic exposure :
Contact with a substance that occurs over a long time (more than 1 year) [compare with acute exposure and intermediate duration exposure]

Cluster investigation:
A review of an unusual number, real or perceived, of health events (for example, reports of cancer) grouped together in time and location. Cluster investigations are designed to confirm case reports; determine whether they represent an unusual disease occurrence; and, if possible, explore possible causes and contributing environmental factors.

Community Assistance Panel (CAP) :
A group of people from a community and from health and environmental agencies who work with ATSDR to resolve issues and problems related to hazardous substances in the community. CAP members work with ATSDR to gather and review community health concerns, provide information on how people might have been or might now be exposed to hazardous substances, and inform ATSDR on ways to involve the community in its activities.

Comparison value (CV) :
Calculated concentration of a substance in air, water, food, or soil that is unlikely to cause harmful (adverse) health effects in exposed people. The CV is used as a screening level during the public health assessment process. Substances found in amounts greater than their CVs might be selected for further evaluation in the public health assessment process.

Completed exposure pathway:
[see exposure pathway].

Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) :
CERCLA, also known as Superfund, is the federal law that concerns the removal or cleanup of hazardous substances in the environment and at hazardous waste sites. ATSDR, which was created by CERCLA, is responsible for assessing health issues and supporting public health activities related to hazardous waste sites or other environmental releases of hazardous substances. This law was later amended by the Superfund Amendments and Reauthorization Act (SARA).

Concentration :
The amount of a substance present in a certain amount of soil, water, air, food, blood, hair, urine, breath, or any other media.

Contaminant :
A substance that is either present in an environment where it does not belong or is present at levels that might cause harmful (adverse) health effects.

Delayed health effect :
A disease or an injury that happens as a result of exposures that might have occurred in the past.

Dermal :
Referring to the skin. For example, dermal absorption means passing through the skin.

Dermal contact :
Contact with (touching) the skin [see route of exposure].

Descriptive epidemiology :
The study of the amount and distribution of a disease in a specified population by person, place, and time.

Detection limit :
The lowest concentration of a chemical that can reliably be distinguished from a zero concentration.

Disease prevention :
Measures used to prevent a disease or reduce its severity.

Disease registry :
A system of ongoing registration of all cases of a particular disease or health condition in a defined population.

United States Department of Defense.

United States Department of Energy.

Dose (for chemicals that are not radioactive) :
The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs.

Dose (for radioactive chemicals) :
The radiation dose is the amount of energy from radiation that is actually absorbed by the body. This is not the same as measurements of the amount of radiation in the environment.

Dose-response relationship :
The relationship between the amount of exposure [dose] to a substance and the resulting changes in body function or health (response).

Environmental media :
Soil, water, air, biota (plants and animals), or any other parts of the environment that can contain contaminants.

Environmental media and transport mechanism :
Environmental media include water, air, soil, and biota (plants and animals). Transport mechanisms move contaminants from the source to points where human exposure can occur. The environmental media and transport mechanism is the second part of an exposure pathway.

United States Environmental Protection Agency.

Epidemiologic surveillance:
[see Public health surveillance].

Epidemiology :
The study of the distribution and determinants of disease or health status in a population; the study of the occurrence and causes of health effects in humans.

Exposure :
Contact with a substance by swallowing, breathing, or touching the skin or eyes. Exposure may be short-term [acute exposure], of intermediate duration, or long-term [chronic exposure].

Exposure assessment :
The process of finding out how people come into contact with a hazardous substance, how often and for how long they are in contact with the substance, and how much of the substance they are in contact with.

Exposure-dose reconstruction :
A method of estimating the amount of people's past exposure to hazardous substances. Computer and approximation methods are used when past information is limited, not available, or missing.

Exposure investigation :
The collection and analysis of site-specific information and biologic tests (when appropriate) to determine whether people have been exposed to hazardous substances.

Exposure pathway :
The route a substance takes from its source (where it began) to its end point (where it ends), and how people can come into contact with (or get exposed to) it. An exposure pathway has five parts: a source of contamination (such as an abandoned business); an environmental media and transport mechanism (such as movement through groundwater); a point of exposure (such as a private well); a route of exposure (eating, drinking, breathing, or touching), and a receptor population (people potentially or actually exposed). When all five parts are present, the exposure pathway is termed a completed exposure pathway.

Exposure registry :
A system of ongoing follow-up of people who have had documented environmental exposures.

Feasibility study :
A study by EPA to determine the best way to clean up environmental contamination. A number of factors are considered, including health risk, costs, and what methods will work well.

Geographic information system (GIS) :
A mapping system that uses computers to collect, store, manipulate, analyze, and display data. For example, GIS can show the concentration of a contaminant within a community in relation to points of reference such as streets and homes.

Grand rounds :
Training sessions for physicians and other health care providers about health topics.

Groundwater :
Water beneath the earth's surface in the spaces between soil particles and between rock surfaces [compare with surface water].

Half-life (t½) :
The time it takes for half the original amount of a substance to disappear. In the environment, the half-life is the time it takes for half the original amount of a substance to disappear when it is changed to another chemical by bacteria, fungi, sunlight, or other chemical processes. In the human body, the half-life is the time it takes for half the original amount of the substance to disappear, either by being changed to another substance or by leaving the body. In the case of radioactive material, the half life is the amount of time necessary for one half the initial number of radioactive atoms to change or transform into another atom (that is normally not radioactive). After two half lives, 25% of the original number of radioactive atoms remain.

Hazard :
A source of potential harm from past, current, or future exposures.

Hazardous Substance Release and Health Effects Database (HazDat) :
The scientific and administrative database system developed by ATSDR to manage data collection, retrieval, and analysis of site-specific information on hazardous substances, community health concerns, and public health activities.

Hazardous waste :
Potentially harmful substances that have been released or discarded into the environment.

Health consultation :
A review of available information or collection of new data to respond to a specific health question or request for information about a potential environmental hazard. Health consultations are focused on a specific exposure issue. Health consultations are therefore more limited than a public health assessment, which reviews the exposure potential of each pathway and chemical [compare with public health assessment].

Health education :
Programs designed with a community to help it know about health risks and how to reduce these risks.

Health investigation :
The collection and evaluation of information about the health of community residents. This information is used to describe or count the occurrence of a disease, symptom, or clinical measure and to evaluate the possible association between the occurrence and exposure to hazardous substances.

Health promotion :
The process of enabling people to increase control over, and to improve, their health.

Health statistics review :
The analysis of existing health information (i.e., from death certificates, birth defects registries, and cancer registries) to determine if there is excess disease in a specific population, geographic area, and time period. A health statistics review is a descriptive epidemiologic study.

Indeterminate public health hazard :
The category used in ATSDR's public health assessment documents when a professional judgment about the level of health hazard cannot be made because information critical to such a decision is lacking.

Incidence :
The number of new cases of disease in a defined population over a specific time period [contrast with prevalence].

Ingestion :
The act of swallowing something through eating, drinking, or mouthing objects. A hazardous substance can enter the body this way [see route of exposure].

Inhalation :
The act of breathing. A hazardous substance can enter the body this way [see route of exposure].

Intermediate duration exposure :
Contact with a substance that occurs for more than 14 days and less than a year [compare with acute exposure and chronic exposure].

In vitro :
In an artificial environment outside a living organism or body. For example, some toxicity testing is done on cell cultures or slices of tissue grown in the laboratory, rather than on a living animal [compare with in vivo].

In vivo :
Within a living organism or body. For example, some toxicity testing is done on whole animals, such as rats or mice [compare with in vitro].

Lowest-observed-adverse-effect level (LOAEL) :
The lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects in people or animals.

Medical monitoring :
A set of medical tests and physical exams specifically designed to evaluate whether an individual's exposure could negatively affect that person's health.

Metabolism :
The conversion or breakdown of a substance from one form to another by a living organism.

Metabolite :
Any product of metabolism.

mg/kg :
Milligram per kilogram.

mg/cm2 :
Milligram per square centimeter (of a surface).

mg/m3 :
Milligram per cubic meter; a measure of the concentration of a chemical in a known volume (a cubic meter) of air, soil, or water.

Migration :
Moving from one location to another.

Minimal risk level (MRL) :
An ATSDR estimate of daily human exposure to a hazardous substance at or below which that substance is unlikely to pose a measurable risk of harmful (adverse), noncancerous effects. MRLs are calculated for a route of exposure (inhalation or oral) over a specified time period (acute, intermediate, or chronic). MRLs should not be used as predictors of harmful (adverse) health effects [see reference dose].

Morbidity :
State of being ill or diseased. Morbidity is the occurrence of a disease or condition that alters health and quality of life.

Mortality :
Death. Usually the cause (a specific disease, a condition, or an injury) is stated.

Mutagen :
A substance that causes mutations (genetic damage).

Mutation :
A change (damage) to the DNA, genes, or chromosomes of living organisms.

National Priorities List for Uncontrolled Hazardous Waste Sites (National Priorities List or NPL) :
EPA's list of the most serious uncontrolled or abandoned hazardous waste sites in the United States. The NPL is updated on a regular basis.

National Toxicology Program (NTP):
Part of the Department of Health and Human Services. NTP develops and carries out tests to predict whether a chemical will cause harm to humans.

No apparent public health hazard :
A category used in ATSDR's public health assessments for sites where human exposure to contaminated media might be occurring, might have occurred in the past, or might occur in the future, but where the exposure is not expected to cause any harmful health effects.

No-observed-adverse-effect level (NOAEL) :
The highest tested dose of a substance that has been reported to have no harmful (adverse) health effects on people or animals.

No public health hazard :
A category used in ATSDR's public health assessment documents for sites where people have never and will never come into contact with harmful amounts of site-related substances.

[see National Priorities List for Uncontrolled Hazardous Waste Sites]

Physiologically based pharmacokinetic model (PBPK model) :
A computer model that describes what happens to a chemical in the body. This model describes how the chemical gets into the body, where it goes in the body, how it is changed by the body, and how it leaves the body.

Pica :
A craving to eat nonfood items, such as dirt, paint chips, and clay. Some children exhibit pica-related behavior.

Plume :
A volume of a substance that moves from its source to places farther away from the source. Plumes can be described by the volume of air or water they occupy and the direction they move. For example, a plume can be a column of smoke from a chimney or a substance moving with groundwater.

Point of exposure :
The place where someone can come into contact with a substance present in the environment [see exposure pathway].

Population :
A group or number of people living within a specified area or sharing similar characteristics (such as occupation or age).

Potentially responsible party (PRP) :
A company, government, or person legally responsible for cleaning up the pollution at a hazardous waste site under Superfund. There may be more than one PRP for a particular site.

ppb :
Parts per billion.

ppm :
Parts per million.

Prevalence :
The number of existing disease cases in a defined population during a specific time period [contrast with incidence].

Prevalence survey :
The measure of the current level of disease(s) or symptoms and exposures through a questionnaire that collects self-reported information from a defined population.

Prevention :
Actions that reduce exposure or other risks, keep people from getting sick, or keep disease from getting worse.

Public availability session :
An informal, drop-by meeting at which community members can meet one-on-one with ATSDR staff members to discuss health and site-related concerns.

Public comment period :
An opportunity for the public to comment on agency findings or proposed activities contained in draft reports or documents. The public comment period is a limited time period during which comments will be accepted.

Public health action :
A list of steps to protect public health.

Public health advisory :
A statement made by ATSDR to EPA or a state regulatory agency that a release of hazardous substances poses an immediate threat to human health. The advisory includes recommended measures to reduce exposure and reduce the threat to human health.

Public health assessment (PHA) :
An ATSDR document that examines hazardous substances, health outcomes, and community concerns at a hazardous waste site to determine whether people could be harmed from coming into contact with those substances. The PHA also lists actions that need to be taken to protect public health [compare with health consultation].

Public health hazard :
A category used in ATSDR's public health assessments for sites that pose a public health hazard because of long-term exposures (greater than 1 year) to sufficiently high levels of hazardous substances or radionuclides that could result in harmful health effects.

Public health hazard categories :
Public health hazard categories are statements about whether people could be harmed by conditions present at the site in the past, present, or future. One or more hazard categories might be appropriate for each site. The five public health hazard categories are no public health hazard, no apparent public health hazard, indeterminate public health hazard, public health hazard, and urgent public health hazard.

Public health statement:
The first chapter of an ATSDR toxicological profile. The public health statement is a summary written in words that are easy to understand. The public health statement explains how people might be exposed to a specific substance and describes the known health effects of that substance.

Public health surveillance:
The ongoing, systematic collection, analysis, and interpretation of health data. This activity also involves timely dissemination of the data and use for public health programs.

Public meeting :
A public forum with community members for communication about a site.

Radioisotope :
An unstable or radioactive isotope (form) of an element that can change into another element by giving off radiation.

Radionuclide :
Any radioactive isotope (form) of any element.

[see Resource Conservation and Recovery Act (1976, 1984)]

Receptor population :
People who could come into contact with hazardous substances [see exposure pathway].

Reference dose (RfD) :
An EPA estimate, with uncertainty or safety factors built in, of the daily lifetime dose of a substance that is unlikely to cause harm in humans.

Registry :
A systematic collection of information on persons exposed to a specific substance or having specific diseases [see exposure registry and disease registry].

Remedial investigation :
The CERCLA process of determining the type and extent of hazardous material contamination at a site.

Resource Conservation and Recovery Act (1976, 1984) (RCRA):
This Act regulates management and disposal of hazardous wastes currently generated, treated, stored, disposed of, or distributed.

RCRA Facility Assessment. An assessment required by RCRA to identify potential and actual releases of hazardous chemicals.

[see reference dose]

Risk :
The probability that something will cause injury or harm.

Risk reduction :
Actions that can decrease the likelihood that individuals, groups, or communities will experience disease or other health conditions.

Risk communication :
The exchange of information to increase understanding of health risks.

Route of exposure :
The way people come into contact with a hazardous substance. Three routes of exposure are breathing [inhalation], eating or drinking [ingestion], or contact with the skin [dermal contact].

Safety factor:
[see uncertainty factor]

[see Superfund Amendments and Reauthorization Act]

Sample :
A portion or piece of a whole. A selected subset of a population or subset of whatever is being studied. For example, in a study of people the sample is a number of people chosen from a larger population [see population]. An environmental sample (for example, a small amount of soil or water) might be collected to measure contamination in the environment at a specific location.

Sample size :
The number of units chosen from a population or an environment.

Solvent :
A liquid capable of dissolving or dispersing another substance (for example, acetone or mineral spirits).

Source of contamination :
The place where a hazardous substance comes from, such as a landfill, waste pond, incinerator, storage tank, or drum. A source of contamination is the first part of an exposure pathway.

Special populations :
People who might be more sensitive or susceptible to exposure to hazardous substances because of factors such as age, occupation, sex, or behaviors (for example, cigarette smoking). Children, pregnant women, and older people are often considered special populations.

Stakeholder :
A person, group, or community who has an interest in activities at a hazardous waste site.

Statistics :
A branch of mathematics that deals with collecting, reviewing, summarizing, and interpreting data or information. Statistics are used to determine whether differences between study groups are meaningful.

Substance :
A chemical.

Substance-specific applied research :
A program of research designed to fill important data needs for specific hazardous substances identified in ATSDR's toxicological profiles. Filling these data needs would allow more accurate assessment of human risks from specific substances contaminating the environment. This research might include human studies or laboratory experiments to determine health effects resulting from exposure to a given hazardous substance.

[see Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and Superfund Amendments and Reauthorization Act (SARA)

Superfund Amendments and Reauthorization Act (SARA) :
In 1986, SARA amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) and expanded the health-related responsibilities of ATSDR. CERCLA and SARA direct ATSDR to look into the health effects from substance exposures at hazardous waste sites and to perform activities including health education, health studies, surveillance, health consultations, and toxicological profiles.

Surface water :
Water on the surface of the earth, such as in lakes, rivers, streams, ponds, and springs [compare with groundwater].

[see public health surveillance]

Survey :
A systematic collection of information or data. A survey can be conducted to collect information from a group of people or from the environment. Surveys of a group of people can be conducted by telephone, by mail, or in person. Some surveys are done by interviewing a group of people [see prevalence survey].

Synergistic effect :
A biologic response to multiple substances where one substance worsens the effect of another substance. The combined effect of the substances acting together is greater than the sum of the effects of the substances acting by themselves [see additive effect and antagonistic effect].

Teratogen :
A substance that causes defects in development between conception and birth. A teratogen is a substance that causes a structural or functional birth defect.

Toxic agent :
Chemical or physical (for example, radiation, heat, cold, microwaves) agents that, under certain circumstances of exposure, can cause harmful effects to living organisms.

Toxicological profile :
An ATSDR document that examines, summarizes, and interprets information about a hazardous substance to determine harmful levels of exposure and associated health effects. A toxicological profile also identifies significant gaps in knowledge on the substance and describes areas where further research is needed.

Toxicology :
The study of the harmful effects of substances on humans or animals.

Tumor :
An abnormal mass of tissue that results from excessive cell division that is uncontrolled and progressive. Tumors perform no useful body function. Tumors can be either benign (not cancer) or malignant (cancer).

Uncertainty factor :
Mathematical adjustments for reasons of safety when knowledge is incomplete. For example, factors used in the calculation of doses that are not harmful (adverse) to people. These factors are applied to the lowest-observed-adverse-effect-level (LOAEL) or the no-observed-adverse-effect-level (NOAEL) to derive a minimal risk level (MRL). Uncertainty factors are used to account for variations in people's sensitivity, for differences between animals and humans, and for differences between a LOAEL and a NOAEL. Scientists use uncertainty factors when they have some, but not all, the information from animal or human studies to decide whether an exposure will cause harm to people [also sometimes called a safety factor].

Urgent public health hazard :
A category used in ATSDR's public health assessments for sites where short-term exposures (less than 1 year) to hazardous substances or conditions could result in harmful health effects that require rapid intervention.

Volatile organic compounds (VOCs) :
Organic compounds that evaporate readily into the air. VOCs include substances such as benzene, toluene, methylene chloride, and methyl chloroform.

Other glossaries and dictionaries:
Environmental Protection Agency ( )

National Center for Environmental Health (CDC) ( )

National Library of Medicine (NIH)( )

For more information on the work of ATSDR, please contact:

Office of Policy and External Affairs
Agency for Toxic Substances and Disease Registry
1600 Clifton Road, N.E. (MS E-60)
Atlanta, GA 30333
Telephone: (404) 498-0080

11 This evaluation was provided to ATSDR by its author, Castine Verrill of the Maine Cancer Registry. Ms. Verrill can be contacted at 207-287-5190. Her address is: Maine Cancer Registry; 11 State House Station; Key Bank Plaza, 4th Floor; Augusta, ME 04333.

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