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Glossary

Action level
A concentration of chemicals at which consideration of action to interdict/prevent exposure occurs, such as surveillance, research, health studies, community education, physician education, or exposure investigations. Alternatively, based on the evaluation by the health assessor, none of these actions may be necessary. Action levels vary depending upon who you talk to.  Most pick one that meets their cause.  Be skeptical of the numbers thrown around until you have evaluated the other values being purported by the "other side".
 
Ah-Receptor:
         The highly toxic group of dioxins and dioxin-like chemicals (also called ligands) enter
         the cell and bind to a protein in the cytoplasm called Ah receptor (AhR). This ligand-AhR
         complex, after further exchange of some smaller proteins (e.g., AhR translocator, ARNT)
         to become 'transformed', enters the nucleus to bind to a specific 'dioxin receptor element'
        (or enhancer) (DRE) of DNA. This DNA interaction occurs 'upstream' of genes which then are
        activated to produce certain enzymes, some of which are highly correlated with the
        subsequent toxicity events.
 
"At-risk" population
A population at a potentially elevated risk due to physiological sensitivity and/or increased exposure to a hazardous chemical.
ATSDR:
         U.S. Agency for Toxic Substances and Disease Registry
BDDs:
Brominated dibenzo-p-dioxins
BDFs :
Brominated dibenzofurans
BEFs :
Bioaccumulation Equivalency Factor:   the bioaccumulation potential for the toxicologically important chlorinated dibenzo-p-dioxins and chlorinated dibenzo-p-furans relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD)for use in calculating 2,3,7,8-TCDD toxicity equivalency concentrations in water as the 2,3,7,8-TCDD toxicity equivalency concentrations relate to deriving human health water quality values.
BODY BURDEN:
Body burden is the accumulated level of a chemical in the body.
        Developmental & Reproductive toxicity have been demonstrated at dioxin body burden
        levels as low as 0.7 ng/kg.  Many other adverse effects are demonstrated at very low levels.
        "The only way we know of to reduce our body burdens from all these persistent lipophilic
        chemicals is, if you are a woman, have a baby".

Dioxin accumulates in biological tissue. The average tissue or "body burden" level of Americans ranges from 36 to 58 ng TEQ/kg lipid (36-58 ppt). Approximately 10% of the population may have tissue levels as much as three times higher than this level.

There is a small difference between the body burdens of dioxins that cause adverse non-cancer effects in animals and average levels in the general human population. Some people who have above average levels are already suffering from the adverse effects of exposure to dioxin.

See definitions of nanograms, KG, TEQ elsewhere in this glossary

CAP:
        Community Advisory Panel, part of MDEQ public participation plan to advise MDEQ on Dow
        Chemicals Scope of Work to remediate dioxin contamination in Tittabawassee River flood
        plain and the City of Midland.

CACO
        Corrective Action Consent Order

CDDs
        Chlorinated dibenzo-p-dioxins

Cohort:  A group

CDFs
Chlorinated dibenzofurans
Comparison value
A concentration used to select contaminants of concern at hazardous waste sites that are taken forward in the health assessment process for further evaluation (The terms comparison value and screening level are often used synonymously.)

Congener

Each different form of Dioxin is called a "congener." Dioxin belongs to a family of chemicals with related properties and toxicity. There are 75 different dioxins, or polychlorinated dibenzodioxins (PCDDs), 135 different furans, or polychlorinated dibenzofurans (PCDFs), and 209 different polychlorinated biphenyls (PCBs) 

DLC
Dioxin Like Compound
Dioxin
A term used interchangeably with 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD
 

Dioxin belongs to a family of chemicals with related properties and toxicity. There are 75 different dioxins, or polychlorinated dibenzodioxins (PCDDs), 135 different furans, or polychlorinated dibenzofurans (PCDFs), and 209 different polychlorinated biphenyls (PCBs). Each different form is called a "congener."

Not all of the "dioxin-like" chemicals have dioxin-like toxicity, and the toxic ones are not equally toxic. Only 7 of the 75 dioxins, 10 of the 135 furans, and 12 of the 209 PCBs have dioxin-like toxicity. These 29 different dioxins, furans, and PCBs all exhibit similar toxic effects caused by a common mechanism: binding to a particular molecule known as the aryl hydrocarbon or "Ah" receptor (see Chapter 5 of the CHEJ TSD).

It is believed that the tighter the binding to the Ah receptor, the more toxic the chemical. The most potent member of this family is 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD, which also has the greatest affinity for the Ah receptor.

The word "dioxin" is often used imprecisely. Some people restrict its use only to 2,3,7,8-TCDD, the most toxic and most studied dioxin. Others extend its use to the whole class of chemicals with similar toxicity and whose effects are controlled or triggered by the Ah receptor. In this report, the terms "dioxin" and "dioxins" are used to refer to any of the dioxin family members that bind to the Ah receptor and elicit dioxin like effects.

Dioxin-like compounds
Compounds from a group of halogenated aromatic hydrocarbons that have molecules shaped like TCDD and produce similar toxic effects, such as certain other chlorinated dibenzo-p-dioxins (CDDs) and certain chlorinated dibenzofurans (CDFs), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), brominated dibenzo-p-dioxins (BDDs), and brominated dibenzofurans (BDFs).
Dioxins
A term used interchangeably with chlorinated dibenzo-p-dioxins
EMEG:
An environmental media evaluation guide (EMEG) is a media-specific comparison value that is used to select contaminants of concern at hazardous waste sites.
EPA:
        U.S. Environmental Protection Agency

EI - Exposure Investigation:
Is the collection and analysis of site-specific information to determine if human populations have been exposed to hazardous substances.  The EI is considered a service, NOT a health study.  The results of the EI are site-specific and applicable only to the community involved, in the EI; they are not generalizable to other individuals or populations.

FDA:
        U.S. Food and Drug Administration
GAO:
        U.S. General Accounting Office
HAZDAT:
        ATSDR's Hazardous Substance Release/Health Effects Database

Health Assessment/Consultation:
Is the evaluation of the environmental and health data and community health concerns about a site.  An Assessment, which looks at the broad picture, is more comprehensive than a Consultation, which usually focuses on a specific element.  Each of these activities results in the preparation and release of a document by the same respective title.  These are NOT Health Studies, however recommendations made in these documents may lead to an EI or a Health Study.

Health Study:

A study of exposed persons designed to assist in identifying effects of exposure on public health.  Heath studies can also define the health problems that require further inquiry by means of, for example, health surveillance.  Often confused with Exposure Investigations and/or Health Assessments and Consultations

HHRA
        Human Health Risk Assessment

KILOGRAM - kg:

        Kilogram (kg) is 1000 grams.  A gram is 1/28th of an ounce, A kilogram is about 2.2 pounds

Median

In probability theory and statistics, a median is a number dividing the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to highest value and picking the middle one. If there are an even number of observations, the median is not unique, so one often takes the mean of the two middle values.

At most half the population have values less than the median and at most half have values greater than the median. If both groups contain less than half the population, then some of the population is exactly equal to the median.

Medical Monitoring

The premise of medical monitoring is that it provides a trust fund (funded by polluter, administered by the court) from which individuals who have been exposed to elevated levels of contaminants can receive screening, and if necessary, follow up care, for diseases associated with those contaminants.  The objective of medical monitoring is to screen individuals for risk, and to identify at an early stage illnesses or syndromes associated with contaminant exposure so that ill effects of exposure can be detected early and addressed while there is a better chance of treating and curing, or at least reducing the effects of, diseases associated with the contminant exposure.  Medical monitoring is not a substitute for personal injury claims for individuals who do develop diseases from contaminant exposure.  Those individuals will have their own separate claims, which have been held by the courts to be claims that are not suitable for a class action.

MICROGRAM:
         One microgram is one-millionth of one gram which is 1000 times more than
         a Nanogram and 1000000 times more than a Picogram.  A gram is 1/28th of an ounce.

MRL
A minimal risk level (MRL) is an estimate of the daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure.
MS:
        Multiple sclerosis

NAACCR:
        North American Association of Central Cancer Registries

NANOGRAM - ng:
A nanogram (ng) is a billionth of a gram; a gram is 1/28th of an ounce.
A kilogram is about 2.2 pounds, Ng/kg is equivalent to parts per trillion.
A picogram is a trillionth of a gram.
NEC:
        Not elsewhere classified
NIEHS:
         National Institute for Environmental Health Sciences
NIH:
        National Institutes of Health

NOD:
        Notice of Deficiency, a document issued by the MDEQ to Dow stating all of the problems the agency  as found with Dows  Scope of Work which must be fixed before they will approve the SOW.

Part 201:

        Rules of Michigans Act 451 which pertain to remediation of of polluted sites.
        Includes rules governing disclosure when properties are bought/sold as well
        as due care responsibilites and soil movement restrictions pertaining to anyone,
        including private residential properties classified as a Hazardous Waste "Facility".
PBBs :
Polybrominated biphenyls
PCBs:
Polychlorinated biphenyls
PCSM:

Preliminary Conceptual Site Model.  A conceptual site model is “a three-dimensional “picture” of site conditions that illustrates contaminant distributions, release mechanisms, exposure pathways and migration routes, and potential receptors.” Ref. EPA SSL Guidance User’s Guide

PICOGRAM - pg:
        A picogram (pg) is a millionth of a microgram, or a
        trillionth of a gram. There are 28 grams in an ounce. 
        A Nanogram is a billionth of a gram, 1000 times more
        than a Picogram. 
PCOI:
Possible contaminants of interest
POP:
Persistent Organic Pollutants, dioxin is one of them.
 
POPULATION SINK
"A breeding group that does not produce enough offspring to maintain itself in coming years without immigrants from other populations." (Source: Sibley).  A population or subpopulation in which λ < 1, and which would go extinct if it is isolated from source populations.

POTW:
        Publicly owned treatment works
PPT:
        Parts per trillion.  See Nanogram above.   If the entire state
        of Indiana was paved with 1 square foot floor tiles, 1 tile in
        the entire state would be about equivalent to 1 PPT.  Not much,
        but dioxin affects human health at levels as low as 5 PPT depending
upon how much you already have in you. 
RCRA
        Resource Conservation and Recovery Act.
RDCC 
Residential Direct Contact Criteria.  Hazardous substances can cause developmental effects.  Residential and commercial direct contact criteria are protective of both prenatal and postnatal exposure.  The state of Michigan has set a level of 90 ppt TEQ RDCC for dioxin.    The value of 90 ppt TEQ is also the states soil cleanup criterial for residential soils.   If a hazardous substance poses a carcinogenic risk to humans, the cleanup criteria derived for cancer risk under this section (part 201)   shall be the 95% upper bound on the calculated risk of 1 additional cancer above the background cancer rate per 100,000 individuals.  MDEQ sampling in the Tittabawassee flood plain have detected dioxin levels 80 times higher than the states RDCC.
RI
        Remedial Investigation .
RIWP
        Remedial Investigation Work Plan.
Screening
The process of initially identifying potentially important chemical contaminants and exposure pathways by eliminating those of known lesser significance.
SIC:
        Standard Industrial Classification
SOW:
        Scope of Work.  A SOW is intended to be a preliminary outline that provides an
        overview of the contents of the RI Workplan that Dow will prepare after approval
        of the SOW by MDEQ
TCDD
2,3,7,8-Tetrachlorodibenzo-p-dioxin
TEFs
Toxicity equivalency factors (TEFs) are based on congener-specific data and the assumption that the toxicity of dioxin and dioxin-like compounds is mediated by the Ah receptor and is additive. The TEF scheme compares the relative toxicity of individual dioxin-like compounds to that of TCDD, which is the most toxic halogenated aromatic hydrocarbon.
 
TEQs Toxic Equivalents
Although all dioxin-like compounds are thought to act in the same way, they are not all equally toxic. Their different toxicities may be due to their unique properties of absorption, distribution, metabolism, and elimination in a body and/or strengths of binding to the Ah receptor. Therefore, the health risk of each congener is assessed by rating their toxicities relative to TCDD, the most potent of the dioxins. TCDD is assigned a value of "1" and each of the 17 toxic dioxins/furans and 12 PCBs is assigned a "toxicity factor" that estimates its toxicity relative to TCDD. The resulting estimates are called toxic equivalency factors (TEFs), which have been recently updated by the World Health Organization.1 The toxic equivalency (TEQ) is determined by multiplying the concentration of a dioxin congener by its toxicity factor. The total TEQ in a sample is then derived by adding all of the TEQ values for each congener. While TCDD is the most toxic form of dioxin, 90% of the total TEQ value results from dioxin-like compounds other than TCDD.

The TEQ system is not perfect, but it is a reasonable way of estimating the toxicity of a mixture of dioxin-like compounds. There is good experimental support for the assumptions that underlie the TEQ system.1,2 TEQs make it possible to take toxicity data on TCDD, a compound about which our knowledge is vast, and estimate toxicity for other compounds about which much less is known.

Tittabawassee River:

Located in Michigan, the Tittabawassee River is one of the principal branches of the Saginaw  river and Saginaw County's second largest river. Native Ottawa and Chippewa tribe name for "the water that follows the trail".  Natives pronounced it as Te-ti-pe-wa-say, most locals now pronounce it as Tit-ta-ba-wa-see.

TRI:

Toxics Release Inventory, EPA's attempt to catelog toxic chemical releases. Estimated to have recorded about 1% of what's really going on.

TSCA:
         Toxic Substances Control Act

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