453N89006
NATIONAL AIR TOXICS INFORMATION
CLEARINGHOUSE NEWSLETTER
&EPA Office of Air Quality Planning and Standards May 1989
Research Triangle Park, North Carolina 27711
State and Ten
Association of Local Air Pollution Control Officials
0 /S\rU/^\rP(^(Q) ^tat® anC' ^err'tor'a' ^'r P°"u,'on Program Administrator5
IN THIS ISSUE
HERE'S A QUICK REVIEW OF NATICH LOG ON PROCEDURE AND PASSWORD USE 1
STATE/LOCAL AGENCY SPOTLIGHT: TEXAS AIR CONTROL BOARD
PLACES HIGH VALUE ON MONITORING 2
RECENT AIR RISC WORK HIGHLIGHTED 3
WHAT IS THE HAZARD INDEX APPROACH? 4
IACP STUDY IDENTIFIES VOLATILE ORGANIC COMPOUNDS AS POSSIBLE TRACERS
OF MOBILE SOURCE PARTICULATE EMISSIONS 5
REGION V LAUNCHES GREAT LAKES AIR TOXICS TRANSBOUNDARY PROJECT
BETWEEN U.S. AND CANADA 5
CONTROL TECHNOLOGY CENTER (CTC) SHARES EMISSIONS EXPERTISE 6
UPDATE ON OZONE DEPLETION/CFC LINK: TCA AND CARBON TET MAY BE ADDED
TO NEW PROTOCOL
INHALATION REFERENCE DOSE METHODOLOGY UPDATED 8
LOUISIANA VOC DATA ANALYSIS REPORT NOW AVAILABLE 9
ANTHROPOGENIC EMISSIONS DATA FOR NAPAP INVENTORY AVAILABLE 9
NEW EPA REPORT ON CANCER RISK NEARS COMPLETION 10
HERE'S A QUICK REVIEW OF NATICH LOG
ON PROCEDURE AND PASSWORD USE
The Clearinghouse staff has fielded a number of
questions recently concerning difficulties in logging on
to the data base. The Clearinghouse staff is looking into
the possibility of streamlining the log on procedure, but
in the meantime, the time seems right to provide a step-
by-step walk-through of the procedure. Therefore, the
steps a new user follows are outlined below, with sug-
gestions for current users on updating passwords.
How to Access NATICH
Step 1: Individuals with a State or local agency who
desire access to the NATICH data base should contact
their ERA Regional Office automated data processing
coordinator. Individuals in the private sector contact Lois
Grooms at the National Technical Information Service by
calling (703) 487-4807. The Regional Office contact or
Ms. Grooms then requests authorization directly from the
EPA's National Computer Center (NCC).
Step 2: Upon approval, the NCC sends a letter to
the user assigning a user ID and an account number.
Step 3: The user calls the Clearinghouse staff at
(919) 541-0850 or (FTS) 629-0850 and requests access
to NATICH, providing information on user ID, account
number and affiliation. The Clearinghouse staff contacts
NCC requesting that the ID and account be approved.
(This step currently takes three days for approval.)
Step 4: Concurrently with Step 3, the Clearinghouse
staff authorizes the level of data base access for the user.
Access can be either data viewing only for users not af-
filiated with an agency providing data to NATICH, or it
can be data viewing plus data editing for affiliates of
agencies that do provide data. Note: Data editing is
restricted to data from the user's agency only.
Step 5: The user accesses the data base for the first
time using a temporary password that matches the
user's ID. This password must be replaced during that
J UN 5 1989
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first log on with a new password of the user's choosing,
4 to 8 characters in length. The new password prompt
appears on the natural log on screen. Detailed instruc-
tion designed to walk the user through the actual log on
procedure, including an explanation of the keystrokes,
can be found in the Clearinghouse brochure "Using the
NATICH Data Base," available by contacting the
Clearinghouse staff.
Choosing and Using Passwords
Every NATICH user's password expires about every
three months whether it is used or not. When this hap-
pens, the user will see a message on the screen in-
dicating the password has expired. At this point, the user
should type a new password at the prompt, TAB once to
a second prompt for the new password, type the new
password again and then hit the ENTER key. If this pro-
cedure fails, the user should log off immediately and
then log on again. When the user's password is initially
requested during the second log on, the user should
type the expired password at the prompt and TAB to the
new password prompt and then type a new password.
Then press ENTER. This will avoid the message that the
user's password has failed and should allow him to pro-
ceed with the log on. NOTE: It is advisable to rotate
among three or four passwords.
As always, the Clearinghouse Staff is ready to pro-
vide further assistance if users have questions about the
procedure or are not successful in attempts to log on.
The number is (919) 541-0850 or (FTS) 629-0850. Other
helpful numbers to call when experiencing log on dif-
ficulties are: EPA user support (800) 334-2405 and
telecommunications support (800) 334-0741.
STATE/LOCAL AGENCY SPC
TEXAS AIR CONTROL BOA
HIGH VALUE ON MONITOI
by Doyle Pendleton, Director, Monitoring Progri
The Texas Air Control Board has jurisdiction over all
254 counties in Texas. With a staff of 360 employees, it
is one of the largest State air programs in the country.
Monitoring—the focus of this spotlight—is one aspect of
the TACB's support services in a large air toxics program
including permitting of new sources, control programs
applicable to existing sources, and SARA Section 313
toxic release inventorying.
The TACB began monitoring for air toxics in the
1970s, and the program's growth has been spurred by
knowledge that more than 10 percent of the nation s air
toxic releases occur in this State. Long before
"Right-to-Know" legislation, Texans-particularly Texans
living in the highly industrialized areas of the State near
chemical plants and refineries—have been concerned
about toxic air pollutants. These facts make air toxics
monitoring one of the TACB's highest priorities.
The agency's monitoring program has three distinct
categories:
- ambient community monitoring,
- source-oriented monitoring and
- emergency response.
Ambient Community Monitoring Targets Have
Ranged from Acrylonitrlle to Pesticides
Some monitoring projects in the ambient commu-
nity arena include the Gulf Coast Community Exposure
Study and a pesticide monitoring network in operation
from 1983 through 1989. The Gulf Coast study measured
ambient levels of 10 classes of air contaminants in four
DTLIGH'R
RD PLACES
IING
im, TACB
Texas Gulf Coast counties. The study area of Harris,
Galveston, Jefferson and Orange Counties was chosen
because it is heavily industrialized and highly populated.
The substances monitored were: acrylonitrile,
arsenic, benzene, epichlorohydrin, ethylene oxide, for-
maldehyde, lead, polychlorinated biphenyls and their
combustion products, polyaromatic hydrocarbons and
vinyl chloride. The levels of all the substances detected
were consistent with those measured in other heavily
urbanized areas across the United States; with the
exception of benzene, these were below the agency's
health screening levels.
The pesticide monitoring network was established
in the agricultural areas of Texas to determine commu-
nity impacts of agricultural pesticide use in the State.
Generally, the pesticide monitoring did not reveal any
high levels of the pesticides selected for monitoring. The
Department of Agriculture in Texas is responsible for
investigation of over-spray complaints. The TACB net-
work was designed to measure community exposure to
these chemicals.
The agency has also supported the operation of
EPA's Ongoing Toxic Air Monitoring System in Houston
from 1985 through 1988* This project was designed by
EPA to evaluate methodologies and quality assurance
procedures for monitoring air toxics. The agency is con-
tinuing to support this project. The TACB also supports
operation of EPA's Urban Air Toxics Program in Dallas
and Houston in which air samples are collected and
characterized for formaldehyde, organics and trace
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heavy metals.
A more recent project (January 1989) has been a
cooperative effort with the Galveston County Air
Pollution Control Program. The TACB established a
benzene monitoring station in Texas City, a highly indus-
trialized city near Galveston on the Texas Gulf Coast.
Source-Oriented Monitoring Projects Described
In 1985, the agency began extensive source-
oriented air toxics monitoring and field analysis using a
mobile laboratory. This 40-foot custom-built trailer is a
field base and analytical laboratory for week-long,
around-the-clock, source-oriented community sampling
projects.
Since 1985, the agency's mobile lab has conducted
15 sampling projects throughout Texas. All 15 sites had
been identified as "hot spots" by TACB Regional
Offices. Three of these projects have identified emission
levels of contaminants above the agency's health
screening levels. Based on the results of one study, en-
forcement action resulted in significant reduction of
chloroprene emissions from a large chemical facility in
Houston. The two other studies revealed benzene levels
that suggested the desirability of additional monitoring.
One of these studies was conducted in Texas City and
resulted in the deployment of a new benzene monitoring
station. This station is currently operating on an every-
three-day schedule. The other 12 monitoring studies did
not reveal levels of pollutants exceeding TACB health
screening levels.
The TACB supports EPA's high risk point source
program. As part of this program, in early 1989 the
agency's mobile lab conducted an intensive monitoring
program around two petrochemical facilities in the
Houston area. Monitoring was conducted for carbon
tetrachloride, chloroform, epichlorohydrin, 1,2-dichlor-
oethane (ethylene dichloride), vinyl chloride,
1,3-butadiene, acrolein, hydrogen cyanide, phenol and
methyl methacrylate. An additional high risk point source
sampling and analysis project was also completed in
early 1989 for formaldehyde at a large chemical plant
near Bishop in south Texas.
In addition to air sampling, the TACB also conducts
soil sampling studies when there is known air pollutant
deposition. A recent project in Bryan, Texas, involved ex-
tensive soil and dust sampling for arsenic in the vicinity
of a pesticide-blending facility and resulted in enforce-
ment action against the company. The agency is current-
ly identifying other sources in the State in which soil
sampling may be used to help characterize emissions.
Emergency Response Available
with Specially Designed Trailer
The agency's Air Toxics Response Program is
designed to provide a state-of-the-art monitoring
capability during emergencies involving actual or poten-
tial releases of air toxics such as may occur during rail car
derailments. A 40-foot goosenecked trailer similar in
design to the mobile lab carries analytical and sampling
survey instruments, communications equipment,
weather instrumentation and personnel decontamina-
tion facilities.
Statewide Air Toxics Monitoring Network
Is Among Future Plans
The agency is currently pursuing a plan to establish
the Texas Cooperative Monitoring Program. This pro-
gram will be a cooperative effort between the TACB and
the industrial business community. The goal of the pro-
gram is to establish an extensive Statewide network of
air toxics monitoring stations. The program is scheduled
to begin its initial monitoring effort in September.
For details on the TACB monitoring program, call its
director, Doyle Pendleton, at (512) 451-5711.
* See related articles in the April 1984, May 1985, March
1986 and June 1987 issues.
RECENT AIR RISC WORK HIGHLIGHTED
The EPA established the Air Risk Information
Support Center (Air RISC) in 1988* to provide assistance
to State and local air pollution control agency personnel
in the areas of health, exposure and risk assessment for
air toxics. During its first year of operation, Air RISC has
initiated several projects, including the Air RISC
Workshops on Risk Assessment and Risk Communica-
tion, a glossary of risk assessment-related terms, and
a directory of information sources for risk assessment.
Air RISC responded to over 400 requests for assistance
from State and local agencies, and EPA Regional
Offices. An example of one recent Air RISC response to
an agency's request for help appears below.
The Air RISC Hotline received a request from the
State of Minnesota for assistance in reviewing a risk
assessment for a paint spraying facility. In the risk
assessment prepared by a permit applicant, health ef-
fects benchmark levels were derived for more than 50
chemicals and exposure concentrations were modeled.
The complexity of the mixture of chemicals emitted from
the facility and questions about the approach used to
assess the acute and chronic noncancer health effects
prompted the State agency to call the Air RISC Hotline
and request support.
The Hazard Index approach [see box] was used in
the risk assessment submitted to the State. The health
effects benchmark levels developed by the permit ap-
plicant were established using the available American
3
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Conference of Governmental Industrial Hygienists
(ACGIH) Threshold Limit Values (TLVs) and dividing
by uncertainty factors. The resulting health effects
benchmark levels were then compared to the
modeled short and long-term exposures. The State
requested that Air RISC comment on the approach
used.
Since risk assessment of noncancer effects of
complex mixtures is a relatively new field, there is little
information available for guidance, standard ap-
proaches, or standard health effects benchmark
levels. Air RISC staff reviewed EPA guidelines and other
Agency documents on mixtures in order to evaluate the
risk assessment submitted to the State. Staff members
from the Office of Air Quality Planning and Standards
responded to the State agency indicating that the risk
assessment was a reasonable attempt to assess a
complex mixture. Additionally, they outlined three areas
of uncertainty in the analysis that would merit State con-
sideration in their decision making process. First, it is not
clear that the health effects benchmark levels derived
from TLVs are set at levels which are consistently pro-
tective for the general population. Second, different
health effects benchmark levels should be used for
various toxicological endpoints caused by a chemical to
ensure that all effects are accounted for. Third, the
assumption that effects are additive may be more uncer-
tain as the complexity of the mixture increases.
*See the July 1988 issue (pages 4-5) for descriptions of
Air RISC's three categories of assistance.
WHAT IS
THE HAZARD
INDEX APPROACH?
The Hazard Index (HI) approach is an ap-
proach that is being more commonly used in the
risk assessment of mixtures. The HI for a single
chemical is the ratio of the modeled or measured
concentration for that chemical to a health effects
benchmark level established for the chemical. If
this ratio is greater than one, then the exposure ex-
ceeds the health effects benchmark level.
Where the risk assessment of mixtures is
desired, the HI is calculated as the sum of the
ratios. If the sum is greater than one, the exposure
exceeds the overall health effects benchmark
level for the mixture. An additional procedure that
may be used is to calculate the HI for a specific
toxic endpoint or target tissue. To do this, a health
effects benchmark level must be derived for each
toxic endpoint or target tissue of concern (for ex-
ample, liver, kidney, upper respiratory tract, lung).
The ratio cited above is then calculated for each
toxic endpoint separately and the ratios for all the
chemicals in the mixture are added for that end-
point, resulting in a toxic endpoint-specific HI. An
important uncertainty in this approach is that it
assumes that effects are additive. No accommoda-
tion is made for synergism or antagonism by this
approach.
This approach relies heavily on the quality of
the data upon which the health effects benchmark
values are based. For a complex mixture, there
may be chemicals which have a strong data base
and a reference value can be derived with high
confidence, and other chemicals with very little
data for which there is little confidence in the
reference value. Likewise, some chemicals will
have data on multiple toxic endpoints (for example,
liver, kidney, and central nervous system), while
others will have limited or no information on poten-
tially important endpoints.
The HI approach does not account in any way
for differences in quality of the data bases or con-
fidence in the health effects benchmark level. Ad-
ditionally, this approach does not account for
various assumptions which may be incorporated
in adopted values such as from the ACGIH TLV
listings. The accuracy of a resulting risk assess-
ment will depend on many factors including
assumptions about the population of interest. The
TLVs in this instance were developed as guidelines
for preventing specific effects in the healthy, work-
ing male population exposed eight hours per day.
They were not designed to protect a residential
population at a facility property line which might be
the population of interest. Another limitation of
health effects benchmark levels derived from TLVb
is that the benchmark level will only account for the
effects which the TLVs were designed to prevent.
In interpreting the results of the HI approach,
therefore, consideration should be given to the
limitations associated with the health effects
benchmark levels.
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IACP STUDY IDENTIFIES VC
COMPOUNDS AS POSSIBLE
SOURCE PARTICULATE EM
Finding suitable substitutes for lead as a tracer for
mobile source emissions is critical for future receptor
modeling studies. This is because (1) the amount of lead
allowed in gasoline has decreased greatly in recent
years and (2) most vehicles produced in the United
States since 1975 are equipped with catalytic converters
which require unleaded gasoline. These events are
causing mobile source-related ambient concentrations
of lead to diminish to the extent that either accurate
measurements will no longer be possible or formerly
negligible sources of ambient lead will reduce the
reliability of motor vehicle-derived lead as an accurate
tracer.
Receptor modeling to determine source impact is
preferable to source modeling because it characterizes
concentrations of chemical species as they actually
exist in the atmosphere. This implicitly includes the com-
plex influences of emissions rate, transport, deposition
and atmospheric chemistry. Thus, a compound which
might at first appear to be a good tracer because of its
abundance in a source's emissions may ultimately
prove unsatisfactory because of other characteristics.
For example, emission constituents which preferen-
tially deposit on the ground may significantly alter the
emission stream, or a loss of tracer compounds may
occur due to atmospheric transformation. By focusing
on the measured species at the point of interest in the
ambient environment and their observed mutual correla-
tions, much of the intervening complexity can be
avoided.
Comprehensive field studies were conducted
recently in Boise, Idaho, and Roanoke, Virginia, as part
of EPA's Integrated Air Cancer Project (IACP). In Boise,
several volatile organic compounds (VOCs) were iden-
tified as candidates for tracers of fine particulate carbon
and extractable organic matter (EOM) from mobile
sources. They include ortho-xylene, 2-methylhexane,
3-methylhexane, methylcyclohexane, 2,3,4-trimethyl-
DLATILE ORGANIC
TRACERS OF MOBILE
ISSIONS
pentane, 2,2,4-trimethylpentane, and 2-methylpentane.
Boise was selected as a study site because it has no ma-
jor manufacturing or industrial sources, and because the
airshed is mainly affected by mobile sources and
residential wood combustion.
The VOCs' identification resulted from a multiple
screening procedure in which the ambient concentra-
tions of a candidate VOC were first required to have both
a high correlation with ambient concentrations of fine
particulate lead and a low correlation with soil-corrected
fine particle potassium, a previously demonstrated
tracer of woodsmoke. Data sets for each VOC surviving
this screening were then substituted in multi-linear
regression representations of the carbon and EOM data.
Successful VOCs resulted in a squared multiple correla-
tion coefficient (r2) at least as good as those with
potassium and lead, and estimates of the woodsmoke
and mobile source contributions virtually the same as
with potassium and lead. The soundness of using the
final VOCs as mobile source tracers was affirmed by
noting their observed low abundance in chimney
samples collected from houses in Boise and consider-
ing what is known about mobile source emissions (both
tailpipe and evaporative).
It remains to be seen whether these several VOCs
will be useful as mobile source tracers in more complex
airsheds and during the various seasons. An encourag-
ing feature of this study is that the selected VOCs seems
to have worked well as tracer chemicals even though
mobile source emissions were not the dominant source
in the airshed. Screening procedures analogous to those
employed for the VOCs are also being applied to
polycyclic aromatic analyses of the fine particulate
organics.
For more information on this topic or on the In-
tegrated Air Cancer Project, please call Barbara M.
Andon, IACP Coordinator, (919) 541-7532 or (FTS)
629-7532.
REGION V LAUNCHES GRE
TRANSBOUNDARY PROJE<
U.S. AND CANADA
Toxic emissions from point, area, and mobile
sources can pose an unacceptable health risk. Further,
these sources can represent the origin of total at-
mospheric emissions of air toxicants with deposition oc-
curring far downwind. During the summer of 1988, the
AT LAKES AIR TOXICS
CT BETWEEN
U.S. Environmental Protection Agency (EPA) Region V
undertook a project to quantify and assess the impacts
of air toxicants in the Michigan-Ontario transboundary
area.
This project, in coordination with the State of
5
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Michigan, the Wayne County Department of Public
Health, the Ontario Ministry of the Environment, and En-
vironment Canada, will investigate public health impacts
on both U.S. and Canadian residents from various
sources that emit air toxicants. The list (see Table 1 for
pollutant categories and examples) consists of 58 com-
pounds (or classes of compounds) that have been iden-
tified by the International Joint Commission as critical
pollutants, compounds identified in the Upper Great
Lakes Connecting Channels Study, compounds that
were identified in the Great Lakes Water Quality Agree-
ment between the United States and Canada, and other
compounds for which specific health effects information
is available. The project will focus primarily on sources
located within approximately 30 miles (50 kilometers) of
the Detroit and St. Clair Rivers, including the
Detroit/Windsor area and the Port Huron/Sarnia area.
This project is expected to have four components:
an emissions inventory, dispersion modeling, risk
assessment, and deposition analysis. The first compo-
nent involves the identification of sources that have
emissions of specific pollutants. This component will
also involve the quantification of these compounds to
form an emissions inventory. The inventory will in turn
be used in a modeling analysis which will serve as the
basis for estimating the exposure of the transboundary
residents to the specified pollutants. The third compo-
nent will estimate the cumulative risk that may occur due
to inhalation of the compounds emitted from the sources.
The fourth component involves an estimation of the
deposition of these compounds into the watershed
basin.
| It is anticipated that this project will be completed
this summer. For further information, call Pamela Blakley
at (312) 886-1767.
TABLE 1.
LIST OF POLLUTANT CATEGORIES
Pollutant Category* Example Pollutants
Acutely Toxic Asbestos
Chlorinated dioxins
Ethylene oxide
Chemical Production Ethylene dibromide
Ethylene dichloride
Heptachlor epoxide
Metals Arsenic
Beryllium
Cadmium
Monomers-Polymers Melamine
Acrylonitrile
Ethyl acrylate
PAHs Benzo(a)pyrene
Coke oven emissions
Chlorinated dibenzofurans
Pesticides Aldrin
Chlordane
Heptachlor
VOCs Benzene
Carbon tetrachloride
Chloroform
Chlorinated Solvents Methylene chloride
Perchloroethylene
Trichloroethylene
"Some pollutants do not fall into one category exclusively.
CONTROL TECHNOLOGY C
SHARES EMISSIONS EXPER
The CTC, now in its third year, continues to respond
to the need for transfer of air emissions expertise from
Federal to State and local agencies. Although the Center
was described in detail at its debut (December 1986
Newsletter), the following paragraphs will acquaint a new
audience with CTC services and cover recent expansion
of services.
The Center is a collaborative effort of the U.S. En-
vironmental Protection Agency's (EPA's) Office of Air
Quality Planning and Standards, Air and Energy
Engineering Research Laboratory, and Center for En-
vironmental Research Information. The CTC provides
three levels of support: Hotline assistance, engineering
assistance, and technical guidance designed for client
State and local agencies, and EPA Regional Offices.
Regulatory agencies may call the CTC Hotline at
;entei? (ctc)
TISE
(919) 541-0800 or (FTS) 629-0800 to discuss a problem
with an EPA staff engineer who is knowledgeable in the
field of concern. More in-depth information may be pro-
vided if required. EPA's new Hotline contact, Bob
Blaszczak, is the first point of communication for all CTC
services described here.
Beyond Hotline assistance, the CTC provides
engineering assistance, which is short-term, in-depth
engineering analysis in a specific area that may not have
widespread applicability. An example is the CTC's
response to a request from the State of Florida's Bureau
of Air Quality Management. Florida was concerned
about emissions from the burning of agricultural plastics
possibly contaminated with pesticides. An EPA scientist
designed a simulation and sampling plan to examine two
modes of burning. He then burned actual field samples
6
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of unused and contaminated plastic and analyzed the
emissions for combustion gases, volatile and
semivolatile organics, particulate material, and toxic and
mutagenic activity. The plastic and emission samples
were also analyzed for the presence of several
pesticides to which the plastic may have been exposed.
The EPA scientist provided the State of Florida with a
technical paper discussing the results of these analyses,
which he presented at a meeting as requested by the
State.
The CTC's third level of assistance is usually longer-
term, broader in scope, and more widely applicable than
the above scenario. An example of the CTC's technical
guidance is its Hospital Waste Incinerator Operator Train-
ing Materials, which were developed in cooperation with
EPA's Region 3, Maryland, and EPA's Air Pollution Train-
ing Institute in response to widespread concern on this
subject. The CTC is developing an operation and
maintenance manual for State agency engineers and
recently conducted a trial run of a course for hospital in-
cinerator operators. The manual and student training
materials are currently being distributed. Inquiries can
be directed to Bob Blaszczak at the CTC Hotline number.
In response to several Hotline calls, the CTC is also
providing technical guidance by conducting a study to
describe and quantify volatile organic compound (VOC)
emissions from the manufacture of fiberglass marine
structures. The CTC will use existing data from the
fiberglass boat manufacturing industry to provide an
assessment of the industry, as well as to determine other
potential air pollution problems. The CTC will then iden-
tify and characterize potential VOC control options for
the manufacture of fiberglass marine structures. The
report is expected to be available to regulatory agencies
this summer.
Another example of the CTC's technical guidance
is its evaluation of new technology for cleaning printing
equipment, one that avoids the use of organic solvents.
The new cleaning method uses ultrasonic waves in a
water-based medium and may reduce VOC emissions,
minimize hazardous waste generation, and extend
useful life of the equipment. The CTC will publicize its
findings and identify other applications for ultrasonic
cleaning technology. This report is scheduled for com-
pletion in June.
Whether an agency or Regional office requires an
in-depth analysis of a specific problem, longer-term
guidance of a broader scope, or simply discussion with
an authority in a certain area of emissions, a Hotline call
to the CTC is the first step toward finding expert advice
and assistance. The Hotline may also be contacted to
obtain copies of reports on the projects described above
as well as its other publications.
UPDATE ON OZONE DEPLi
TCA AND CARBON TET MS
TO NEW PROTOCOL
Ozone Depletion Regulatory
Background Outlined
The threat of ozone depletion in the stratosphere by
chlorine released from chlorofluorocarbons (CFCs) was
first noted about 15 years ago. In 1981, in response to
a growing scientific consensus, the United Nations
Environment Programme began negotiating a multi-
national response to the problem. As a result, the Vien-
na Convention for the Protection of the Ozone Layer
(March 1985) provided the first framework for interna-
tional cooperation in research, monitoring and informa-
tion exchange, and led to the Montreal Protocol on
Substances that Deplete the Ozone Layer (September
1987). In August 1988, the Environmental Protection
Agency (EPA) promulgated regulations to implement the
Protocol; these became effective January 1,1989.
The next meeting of the signatory nations is
scheduled for April 1990, at which time changes in cur-
rent control measures will be considered. In view of the
continuing severe depletion of the ozone layer, more
comprehensive controls may be expected.
In August 1988, the EPA published an Advance
ETION/CFC LINK:
\Y BE ADDED
Notice of Proposed Rulemaking (ANPR) on possible fur-
ther efforts to protect stratospheric ozone. This docu-
ment discussed new scientific information suggesting
that ozone was being depleted at a faster rate than had
originally been anticipated. Since 1969, stratospheric
ozone concentration has decreased 1.7-3.0 percent in
northern mid-latitudes and there has been a dramatic
decrease in springtime Antarctic ozone.
TCA and Carbon Tet Among CFCs Examined
The changes over the last 20 years should not have
occurred, according to current atmospheric models, until
the year 2050. Either the model significantly
underestimates the link between CFCs and ozone deple-
tion or the level of chlorine in the stratosphere from
nonregulated halocarbons has increased beyond expec-
tation. Accordingly, the Agency expects that methyl
chloroform (1,1,1-trichloroethane or TCA) and carbon
tetrachloride will be among the new chemicals sug-
gested for inclusion in the new protocol.
The EPA is particularly concerned about possible
future increases in the use of TCA as a substitute for
7
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other chlorinated solvents such as methylene chloride,
perchloroethylene and trichloroethylene, which are cur-
rently under examination for potential regulatory action
by EPA.
Although carbon tetrachloride has been recog-
nized as a very efficient depleter of ozone, it was not
originally included in the protocol because it is used
primarily as a chemical intermediate in the manufacture
of various CFCs and emissions from this use were
believed to be small and well controlled. (The EPA cur-
rently has carbon tetrachloride under assessment for
possible regulation as a hazardous air pollutant.)
However, atmospheric levels have been found to be
greater than expected. This may be attributed to the fact
that Japan, the Eastern Block nations and some
developing countries are using carbon tetrachloride in
the production of pesticides, as a solvent, and in the
manufacture of synthetic rubber and dyes.
EPA and Industry Working to Determine
Alternative Solvents
The EPA does not view shifting from CFCs to other
chlorinated solvents as an acceptable solution to protec-
ting the environment and strongly urges chlorinated sol-
vent manufacturers and users to consider low cost, long-
term solutions that will minimize environmental releases
of chlorinated solvents. The Agency has sponsored with
industry a variety of technological and economic work
groups to discuss alternatives to CFCs in industrial and
commercial uses. For example, EPA and industry are
engaged in cooperative projects to determine whether
electronic components and circuit boards can be
cleaned with aqueous and terpene cleaners instead of
CFC-113 or methyl chloroform.
In addition, the Agency has been working with
chemical manufacturers and industry representatives to
determine the extent to which CFC-113 and methyl
chloroform can be replaced in metal cleaning and
degreasing. The EPA is also working with the U.S.
Department of Defense to revise and/or eliminate military
procurement specifications specifically requiring the use
of chlorinated solvents in precision electronic and metal
cleaning. (Abstracted from the Federal Register, Volume
54, No. 72, April 17, 1989.)
For further information, contact Karla Perri, Division
of Global Change, Office of Atmospheric and Indoor Air
Programs, U.S. EPA, ANR-445, 401 M Street S.W.,
Washington, D.C. 20460, or call (202) 475-7496, (FTS)
475-7496.
INHALATION REFERENCE
METHODOLOGY UPDATED
The new methodology document "Interim Methods
for Development of Inhalation Reference Doses," com-
pleted in April, is being reviewed for final Agency
clearance. During the year and a half since peer review,
EPA has continued to develop the scientific basis for the
methodology by reviewing available information on in-
terspecies differences in pulmonary toxicology, develop-
ing pharmacokinetic modeling approaches for deriving
human equivalent exposure concentrations, and ex-
amining additional data on various physiologic
parameters in humans and experimental animals*
The document includes discussion of the
respiratory tract and factors that determine inhaled dose
including the physicochemical properties of the pollu-
tant. Guidance on the use of human data, choice of tox-
icity studies, application of uncertainty factors, and the
minimum data requirements for inhalation reference
dose (RfDj) derivation is also provided.
What Is an RfD|?
The Agency's effort to develop RfDjs, for both oral
and inhalation exposure, stems from the need to develop
an approach for quantitative risk assessment of health
effects other than for cancer and gene mutations. Prior
to development of the RfDj approach, noncancer health
DOSE
>
risks were assessed using concepts such as the accep-
table daily intake, safety factors, and margin of safety.
Because of difficulties with consistent derivations and
interpretation of these approaches, and in order to
separate risk assessment more clearly from risk
management issues, the RfDj approach was developed.
Until recently, the RfDj approach had been applied
to oral exposures only. However, EPA recognized that
Regional, State, and local agencies needed uniform and
scientifically sound risk assessment procedures to
estimate benchmark inhalation values. The Agency
believes that the interim RfDj approach will be useful to
many in their risk management programs as one part of
the risk assessment process.
How Is an RfD| Derived?
The RfDj derivation involves identification of a
critical study and critical effect, supporting studies, the
incorporation of uncertainty factors, and the calculation
of the RfDj value. A more detailed description of this pro-
cess, including definitions, can be found in the document
or in the Integrated Risk Information System (IRIS) ap-
pendices* The proposed RfDj and supporting documen-
tation is then submitted to the RfDj Work Group, an intra-
agency work group made up of scientists representing
8
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several EPA offices. At its monthly meeting, the Work
Group reviews the submittal, and when a consensus is
reached that supports the RfDj derivation procedure, the
RfDj value is considered to be "verified" and is in-
cluded in the IRIS.
How Many RfOis Have Been Verified?
The Work Group has reviewed documentation files
for 20 chemicals to date and has verified five. These five
are methylene chloride, p-dichlorobenzene, hydrogen
chloride, carbon disulfide and tetrahydrofuran.
Documentation files for an additional 50 chemicals are
being prepared, many of which will be reviewed during
the next year.
For more information on inhalation RfDjS, contact
Annie Jarabek, U.S. EPA, MD-52, Research Triangle
Park, North Carolina 27711, (919) 541-4847, (FTS)
629-4847, or Dan Guth, U.S. EPA, MD-13, Research
Triangle Park, North Carolina 27711, (919) 541-5349,
(FTS) 629-5349.
*See related article in July 1988 issue.
LOUISIANA VOC
DATA ANALYSIS REPORT
NOW AVAILABLE
The report "Statistical Properties of Hourly Concen-
trations of Volatile Organic Compounds at Baton Rouge,
Louisiana" (EPA-450/4-88-007, March 1989) is now
available. The report analyzes 11,000 hourly data values
on 16 volatile organic compounds (VOC) collected since
1985 at Louisiana's Department of Environmental Quali-
ty monitoring site in downtown Baton Rouge. The report
discusses the results of an analysis of data collected
from October 30,1985 to June 30,1987. These data make
it possible to compare averaging times of less a day (for
example, 1-hour, 3-hour, and 8-hour) with the 24-hour
average that is the most common averaging time now
used to collect VOC data.
The data analysis presented in the report concerns
three principal areas: (1) how the hourly VOC values and
the values of other averaging times are distributed, (2)
how well the daily maximum 1-hour, 3-hour, and 8-hour
VOC concentrations can be predicted by 24-hour
average concentrations and (3) how the variability in
VOC concentrations can be explained by such variables
as wind direction, hour of the day, day of week, and
month. The data on benzene are used extensively in the
report in providing the examples given in the discussion
on the above topics; however, the results on all of the
VOC monitored are also contained in the report.
Some of the results described include finding the
hourly concentrations for most of the pollutants to be
lognormally distributed and the 24-hour average con-
centration to be a more reliable predictor for 3-hour and
8-hour maximums than for 1-hour maximums. The im-
pact of the four variables on VOC concentration was
determined to be statistically significant but explained
only a small percentage of the total variability.
For those interested in receiving a copy of the
report, write or call Bob Faoro at U.S. EPA, MD-14,
Research Triangle Park, North Carolina 27711, (919)
541-5459 or (FTS) 629-5459.
ANTHROPOGENIC EMISSIC
FOR NAPAP
INVENTORY AVAILABLE
The U.S. Environmental Protection Agency (EPA)
has published a report "Anthropogenic Emissions Data
forthe 1985 NAPAP Inventory" (EPA/600/7-88-022)that
documents man-made emissions of acid precipitation
precursors during 1985. This comprehensive emissions
data base was developed for the National Acid Precipita-
tion Assessment Program (NAPAP) as a cooperative ef-
fort between the Office of Research and Development,
the Office of Air Quality Planning and Standards, Re-
gional Offices, and State and local environmental
agencies.
)NS DATA
The development of the current emissions inventory
required the investigation of hundreds of thousands of
sources of air pollution. These included stationary or
point sources, such as refineries and utility boilers, as
well as area or dispersed sources such as motor vehi-
cle emissions along highways.
The 1985 emissions inventory spans the 48 con-
tiguous States and the District of Columbia, providing
point source data for over 130,000 individual sources of
acid precursor emissions and area source information
for more than 100 area source categories in each of the
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3,100 U.S. counties. The inventory contains estimates of
emissions of primary pollutants, suifur dioxide, nitrogen
oxides, and volatile organic compounds. Emission data
on carbon monoxide, total suspended particulate mat-
ter, sulfates, hydrogen chloride, hydrogen fluoride, and
ammonia are also included, although these data are less
reliable.
Summaries of emissions data are presented at
various levels, including national, State, and source
categories. Emissions are also analyzed by plant size,
stack height, and general source type. The inventory pro-
vides a history of the 1985 emission inventory develop-
ment process and documents efforts to enhance the na-
tional emission inventory process.
The report was published by the EPA's Air and
Energy Engineering Research Laboratory, Research
Triangle Park, North Carolina. Technical information may
be obtained from the EPA project officer, Robert
Lagemann, at (919) 541-2709 or (FTS) 629-2709.
NEW EPA REPORT
ON CANCER RISK
NEARS COMPLETION
A new EPA report entitled "Cancer Risk from Out-
door Exposure to Air Toxics" is being completed by the
Office of Air Quality Planning and Standards and will be
released soon as an external review draft. The objective
of this study is to improve our understanding of the
magnitude, nature and geographic variability of cancer
risk in the United States due to outdoor exposures of air-
borne toxic pollutants. It is essentially an update of the
1985 EPA study generally referred to as the "Six Month
Study" but is broader in scope because many additional
analyses of cancer risk have been completed since 1985.
The data analyzed in this study were drawn from 25
separate studies that evaluated cancer risk for specific
sources, pollutants or geographic areas. Twenty-three
source categories and 80 different toxic air pollutants
were addressed in one or more of these studies. These
data were used to develop national estimates of the an-
nual cancer incidence in the United States and lifetime
individual risks resulting from exposure to individual or
mixtures of toxic air pollutants.
Individuals and organizations who would like to
receive a copy of this report when it is released should
send a written request to Joseph Padgett, U.S. EPA,
MD-10, Research Triangle Park, North Carolina 27711.
Individuals willing to provide comments for considera-
tion in revising the report for final release should state
so in their report request.
CTC AND AIR RISC HOTLIN
ARE READY TO ASSIST
STATE AND LOCAL AGENC
For answers to control technology questions, State
and local air agencies can call CPA's Control Technology
Center (CTC) Hotline at (919) 541-0800.
ES
IES
Help with questions on health effects, exposure, or
risk assessment associated with air toxics is available
from EPA's Risk Information Support Center {Air RISC)
Hotline at (919) 541-0888.
NEED
HELP?
if your agency needs help in finding information on
a specific air toxics question, you can announce that
need in the National Air Toxics Information
Clearinghouse Newsletter Your colleagues from other
State or local agencies who have such information will
be able to contact you with assistance. In addition, the
Clearinghouse staff would like to receive your ideas for
future Newsletter articles. To list an information need in
the next issue or to submit an article or a suggestion for
a future Newsletter article, please call either Caroline
Miller of the Clearinghouse staff, (919) 541-5519, (FTS)
629-5519, or Susan Buchanan, Radian Corporation,
(919) 541-9100.
10
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The National Air Toxics Information Clearinghouse Newsletter
is published six times a year by the National Air Toxics Information
Clearinghouse to assist State and local agencies making decisions
on noncriteria pollutant emissions. The first issue appeared in
December 1983. The Clearinghouse is being implemented by the
U.S. Environmental Protection Agency, Emission Standards Divi-
sion, Pollutant Assessment Branch as part of a joint effort with the
State and Local Air Pollution Control Officials (ALAPCO). The
National Air Toxics Information Clearinghouse Newsletter is
prepared by Radian Corporation under EPA Contract Number
68-08-0065, Work Assignment 1. The EPA Project Officer is Scott
Voorhees, EPA Office of Air Quality Planning and Standards,
Research Triangle Park, North Carolina 27711, Telephone:
(919)541-5348. The Radian Project Director is Susan Buchanan, P.O.
Box 13000, Research Triangle Park, North Carolina 27709,
(919)541-9100.
The Newsletter is prepared primarily for State and local air
pollution control agencies and is distributed free of charge. Those
wishing to report address changes may do so by writing Meredith
Haley, Radian Corporation, P.O. Box 13000, Research Triangle Park,
North Carolina 27709. Please contact the Project Officer either with
any comments you might have pertaining to this newsletter or with
suggestions for future newsletters. Articles in the newsletter are writ-
ten by Radian Corporation or EPA staff unless otherwise indicated.
The views expressed in the National Air Toxics Information
Clearinghouse Newsletter do not necessarily reflect the views and
policies of the Environmental Protection Agency. Mention of trade
names or commercial products does not constitute any endorse-
ment or recommendation for use by EPA.
-------
Scott Voorhees
Pollutant Assessment Branch
U.S. Environmental Protection Agency
MD-13
Research Triangle Park, NC 27711
L i b r¦ ary
EPA , Regi on II
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