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 studyof 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.
