USING HEALTH BENCHMARKS
We can evaluate the air toxic exposures predicted by
U.S. EPA for 1990 by using something known as Health Benchmarks.
These Health Benchmarks are the concentrations below which
no harm to human health would be expected. It is not always
clear, however, how far above the Health Benchmark an
exposure may be before there is harm. The actual harm
level will vary substantially from pollutant to pollutant.
Still, comparison to a Health Benchmark is a useful tool
for sorting the CEP predictions. If the exposure is below
the Health Benchmark there is probably no need for further
investigation. If the exposure is above the Health Benchmark
there may be some cause for concern and further assessment
is warranted. For carcinogens (substances that cause cancer),
the Health Benchmark is set at the exposure that over
a lifetime could cause a one in a million increase in
the likelihood of getting cancer. For noncarcinogens,
Health Benchmarks are selected to be the concentration
of a toxic pollutant for which exposure is likely to be
free from harm, even if the exposure occurs on a daily
basis.
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THE 25 AIR TOXICS OF
GREATEST CONCERN IN NJ
In New Jersey, our preliminary analysis of the county
average hazardous air pollutant (HAP) concentrations generated
by USEPA's Cumulative Exposure Project: "An
Sab Report: The Cumulative Exposure Project"
(Pdf Format) "Modeled
Outdoor Concentrations of Hazardous Air Pollutants: Analysis
of Data from the Cumulative Exposure Project for the Urban
Area Source Program" (Pdf Format) indicates that
there were 24 carcinogenic chemicals predicted by EPA
to exceed health benchmarks in one or more counties in
1990. One noncarcinogenic chemical, acrolein, was predicted
to exceed the health benchmark throughout the state. These
25 pollutants of concern vary in the extent to which they
are expected to be found in New Jersey and the type of
sources that emit them. These characteristics are summarized
below.
Pollutant
of Concern |
Extent |
Source
of Emissions |
Acrolein |
Statewide |
Mobile
& Area |
Benzene |
Statewide |
Mobile
& Area |
1,3-Butadiene |
Statewide |
Mobile |
Carbon
tetrachloride |
Statewide |
Global
Background |
Chloroform |
Statewide |
Mobile
& Area |
Ethylene
dibromide |
Statewide |
Global
Background |
Ethylene
dichloride |
Statewide |
Mobile
& Area |
Formaldehyde |
Statewide |
Mobile
& Area |
Methyl
chloride |
Statewide |
Global
Background |
Polycyclic
organic matter (POM) |
Statewide |
Mobile,
Area & Point |
Acetaldehyde |
10
to 20 Counties |
Mobile
& Area |
Acrylonitrile |
10
to 20 Counties |
Area |
Arsenic |
10
to 20 Counties |
Mobile,
Area & Point |
Chromium |
10
to 20 Counties |
Mobile,
Area & Point |
p-Dichlorobenzene |
10
to 20 Counties |
Area |
1,3-Dichloropropene |
10
to 20 Counties |
Area |
Nickel |
10
to 20 Counties |
Mobile,
Area & Point |
Vinyl
chloride |
10
to 20 Counties |
Area
& Point |
Cadmium |
1
to 4 Counties |
Area
& Point |
Dioxin |
1
to 4 Counties |
Area
& Point |
Ethyl
acrylate |
1
to 4 Counties |
Point |
Ethylene
oxide |
1
to 4 Counties |
Point |
Hydrazine |
1
to 4 Counties |
Point |
Methylene
chloride |
1
to 4 Counties |
Point |
Trichloroethylene |
1
to 4 Counties |
Area
& Point |
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THE 7 AIR TOXICS ABOVE THE HEALTH
BENCHMARKS NATIONWIDE
Seven of the 148 hazardous air pollutants included in
the Cumulative Exposure Project were predicted to be above
the health benchmarks everywhere in the United States
because of these assumptions about global background levels.
Global background concentrations are the pollutant levels
that are found throughout the continental United States
in "clean air locations," areas where no local
man-made air toxic emissions would be expected. These
seven pollutants (which are all included among the Statewide
Pollutants of Concern above) are:
Benzene
|
Ethylene dibromide
|
Formaldehyde
|
Carbon tetrachloride
|
Ethylene dichloride
|
Methyl chloride
|
Chloroform
|
|
|
These pollutants are found in remote parts of the world
in significant concentrations for three reasons. Some
(such as carbon tetrachloride and ethylene dibromide)
are the result of historical emissions that took place
many years ago, but they are still found in the atmosphere
because they do not tend to break down into other compounds.
Others (such as benzene and formaldehyde) result from
long-range transport of recent emissions. They do not
last in the environment as long as the first group, but
they are emitted in such large quantities around the world,
especially in cities, that they travel on the wind and
are still found in significant quantities in remote and
rural areas. Finally, there are a few (such as methyl
chloride) that are emitted by natural sources (trees,
etc.) as well as by man-made sources. These pollutants
also come from sources that are all over the world and
they persist in the atmosphere for a long time.
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WHAT IS MEANT BY POINT,
AREA AND MOBILE SOURCES, AND GLOBAL BACKGROUND?
- Area Sources: this list includes many types
of sources that are commonly referred to as Point Sources
in New Jersey, such as power plants:
- Solvent Use (such as coating cans, cleaning metal
parts, and dry cleaning)
- Industrial Processes (such as small chemical manufacturing
plants, bakeries, and making scrap metal into new
product)
- Waste Disposal, Treatment and Recovery (including
wastewater treatment and various types of waste
incineration)
- Stationary Source Fuel Combustion (including power
plants, industrial and commercial boilers, and home
heating)
- Storage and Transport (including gas stations
and large gasoline terminals)
- Miscellaneous Sources (such as wildfires, structure
fires, and crop orchard heaters)
- Mobile Sources
- On-road vehicles (cars and trucks)
- Non-road vehicles (lawnmowers, boats, dirt bikes,
etc.)
- Point Sources: this list does not include many
types of sources that are commonly referred to as Point
Sources in New Jersey, such as power plants:
- Refineries
- Municipal Waste Incinerators
- Toxic Waste Transfer, Storage & Disposal Facilities
(known as TSDFs)
- TRI Sources (those facilities that are required
to report their emissions under the Right-to-Know
program)
- Other Point Sources (that have reported emissions
under other state and federal programs)
- Global background
- Historical emissions of persistent pollutants
(such as carbon tetrachloride)
- Long-range transport of recent emissions (such
as benzene)
- Emissions from natural sources (such as methyl
chloride)
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MORE INFORMATION ON EFFECTS
OF AIR TOXICS
Here are two web sites you can visit to learn more about
the health effects of specific air toxics:
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