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Docket Number: 

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40 CFR Part S® 

Lost oif Regulated Substances and 

Thresholds for Accidental Release 

Prevention; Requirements for Petitions; 

Proposed Rule 

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contains at least 50% recycled fiber 

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510 2 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 68 

[A-91-7468; FRL-455J-3] 

List of Regulated Substances and 

Thresholds for Accidental Release 

Prevention; Requirements for Petitions 

under Section 112(r) of the Clean Air 

Act as Amended 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Clean Air Act 

Amendments of 1990, signed into law 

on November 15,1990 , include 

provisions for chemical accident 

prevention. The Environmental 

Protection Agency is proposing a list of 

regulated substances and threshold 

quantities as required under section 

112(r) of the Clean Air Act as amended. 

The list is composed of three distinct 

categories: list of 100 toxic substances, 

list of 62 flammable substances (gases 

and volatile liquids), and commerciai 

explosives as defined by the Department 

of Transportation (DOT) in Division 1.1 

(explosives with mass explosion 

hazard); individual explosives are not 

included. The list and threshold 

quantities will determine the need for 

owners and operators of facilities to 

comply with future regulations 

addressing the prevention and detection 

of accidental releases to be proposed 

later. EPA is also publishing the 

requirements for the petition process 

that will be used to add or delete 

chemicals from the final list. 

DATES: Comments must be submitted on 

or before March 22,1993 . EPA plans to 

hold at least one public hearing; date, 

time and location will be published 

shortly in the Federal Register. 

ADDRESSES: Comments may be mailed 

or submitted to: Environmental 

Protection Agency, Air Docket (LE-131), 

Attn: Docket No. A-91-74 , Waterside 

Mall, 401 M St. SW., Washington, DC 

20460. Comments must be submitted in 

duplicate. 

Docket: Supporting information used 

in developing this proposed rule is 

contained in Docket No. A-91-74 . This 

docket is available for public inspection 

and copying between 8:30 a.m. and 12 

noon, and between 1:30 and 3:30 p.m., 

Monday through Friday at the address 

listed below. A reasonable fee may be 

charged for copying. 

FOR FURTHER INFORMATION CONTACT: 

Vanessa Rodriguez, (202) 260-7913, 

Chemical Emergency Preparedness aad 

Prevention Office, OS-120, 

Environmental Protection Agency, 401 

M S . SW., Washington, DC 20460, or 

the Emergency Planning and 

Community Right-to-Know Hot Line at 

1-8S0-535-O202. 

SUPPLEMENTARY INFORMATION: 

I. Introduction 

A, Statutory Authority 

B. Background 

II. Qean Air Act Amendments of 1990 

{CAAA) 

III. List of Substances and Thresholds 

A. Introduction 

B. Factors Considered in Defining List 

Criteria 

C. Criteria Options Considered 

D. List of Substances 

E. Threshold Quantities 

IV. Other Issues 

A. State Programs 

B. OSHA's List of Highly Hazardous 

Chemicals 

C. Relationship to EPCRA (SARA Title III) 

Section 362/303 

D. Agricultural Nutrient Exemption 

E. Information Gathering Efforts 

V. Petitions for Additions and Deletions 

A. Information Required from Petitioner 

B. Petition Process 

VI. Discussion of the Proposed Rule 

VII. Required Analyses 

A.E.O. 12291 

B. Regulatory Flexibility Act 

C. Paperwork Reduction Act 

I. Introduction 

A. Statutory Authority 

This notice of proposed rulemaking 

(NPRM) is being issued under section 

11* ) ofthe Clean Air Act (CAA or Act) 

as amended (42 U.S.C. 7412, 7601). 

B. Background 

Public awareness of the potential 

danger from accidental releases of 

hazardous chemicals has increased over 

the years as serious chemical accidents 

hav® occurred around the world (e.g., 

the 1974 expdosten in Flixborough, 

England, and the 1976 release of dioxin 

in Seveso, Italy). Public concern 

intensified following the 1984 release of 

metfiyl isocyanate in Bhopal, India, 

which killed more than 2,000 people 

living near the facility. A subsequent 

release from a chemical facility in 

Institute, West Virginia, sent more than 

100 people to the hospital and made 

Americans aware that such incidents 

can and do happen in the United States. 

IB response to this public concern and 

the hazards that exist, the U.S. 

En^ronmental Protection Agency (EPA) 

began its Chemical Emergency 

Preparedness Program (CEPP) in 1985, 

as fart of the Agency's Air Toxics 

Strategy. CEPP was a voluntary program 

to encourage state and local authorities 

to identity hazards in their areas and to 

plaa for chemical emergency response 

actions. In 1986, Congress adopted 

many ofthe elements of CEPP in the 

Emergency Planning and Community 

Right-to-Know Act of 1986 (EPCRA), 

also known as Title III of the Superfund 

Amendments and Reauthorization Act 

of 1986 (SARA Title III). EPCPA (SARA 

Title III) requires states to establish state 

ahd local emergency planning groups, 

namely, the State Emergency Response 

Commissions (SERCs) and the Local 

Emergency Planning Committees 

(LEPCs), to develop emergency response 

plans for each community. EPCRA 

(SARA Title III) requires facilities to 

provide information on the hazardous 

chemicals they have on site; the 

information collected is available to the 

public through the SERC/LEPC 

structure. This information forms the 

foundation of both the emergency 

response plans and the public-industry 

dialogue on risks and risk reduction. 

EPCRA (SARA Title IU) did not 

mandate that facilities establish 

accident prevention programs. However, 

Congress acknowledged the importance 

of accident prevention by requiring 

EPA, under EPCRA (SARA Title III) 

section 305(b), to conduct a review of 

emergency systems to monitor, detect, 

and prevent chemical accidents. The 

final report to Congress, Review of 

Emergency Systems (EPA, 1988), 

concluded that the prevention of 

accidental releases requires an 

integrated approach that considers 

technologies, operations, and 

management practices. The report 

emphasized the importance of 

management commitment to safety. 

Although EPCRA (SARA Title III) did 

not directly address accident 

prevention, EPA recognized that 

prevention, preparedness, and response 

form a continuum. Therefore, in 1986, 

EPA established a chemical accident 

prevention program to collect 

information on chemical accidents and 

work with other groups to increase 

knowledge of prevention practices and 

encourage industry to improve safety at 

facilities. Under this program, EPA 

developed its Accidental Release 

Information Program (ARIP) to collect 

data on the causes of chemical accidents 

and the steps facilities take to prevent 

recurrences. EPA also developed a 

program for conducting chemical safety 

audits at facilities. Through the audit 

program, EPA headquarters and regional 

staff as well as state and local officials 

learned about integrated approaches to 

process safety from facilities. EPA has 

also worked with trade associations, 

professional organizations, labor, 

environmental groups, and other 

Federal agencies to determine how best 

to reach smaller operations, which the 

section 305(b) study indicated are less 
P.4 

Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5103 

aware of risks than larger facilities. EPA 

has also been an active participant in 

international efforts related to chemical 

accident prevention, particularly 

through the Organization for Economic 

Cooperation and Development (OECD), 

which has held five international 

workshops from 1989 through 1991 to 

discuss issues related to accident 

prevention, preparedness, and response, 

and has developed guidelines for 

member countries. 

In addition to EPA's work in this area, 

other agencies and states have 

developed programs related to chemical 

accident prevention. Recently, the 

Occupational Safety and Health 

Administration (OSHA) has 

promulgated a final rule on chemical 

process safety management (57 FR 6356, 

February 24,1992). Three states—New 

Jersey, California, and Delaware—have 

adopted regulations requiring facilities 

to prepare and implement risk 

management plans. A fourth state, 

Nevada, has recently enacted legislation 

on chemical process safety management. 

Professional and trade organizations 

have also developed programs in this 

area. For example, the Center for 

Chemical Process Safety ofthe 

American Institute of Chemical 

Engineers has published guidance on 

the management of chemical process 

safety. The Chemical Manufacturers' 

Association has adopted a Responsible 

CareTM program, which all members 

must comply with to maintain 

membership. The American Petroleum 

Institute has developed a similar 

program, Management of Process 

Hazards; Recommended Practice 750 

(RP 750), for its members. In 1982, the 

European Community adopted the 

Seveso Directive (82/501/EEC, as 

amended), which requires facilities 

handling certain chemicals to develop a 

safety report that is similar to a risk 

management plan. 

II. Clean Air Act Amendments of 1990 

(CAAA) 

In the Clean Air Act Amendments of 

1990 (CAAA), signed into law on 

November 15,1990, Congress added 

paragraph (r) to section 112 for the 

prevention of chemical accidents. The 

goals of the chemical accident 

prevention provisions are to focus on 

chemicals that pose a significant hazard 

to the community should an accident 

occur, to prevent their accidental release 

and to minimize the consequences of 

such releases. 

Section 112(r) ofthe CAA has a 

number of provisions. It establishes a 

general duty for owners and operators of 

stationary sources, who produce, 

process, handle, or store substances 

listed under section 112(r)(3) and any 

other extremely hazardous substances, 

to comply and perform specific 

activities to prevent and mitigate 

accidental releases. The general duty 

requirements apply to stationary sources 

regardless of the quantity of substances 

managed at the facility. Activities such 

as hazards identification using 

appropriate hazard assessment 

techniques, designing, maintaining and 

operating a safe facility, and minimizing 

the consequences of accidental releases 

if they occur would be essential 

activities that must be performed to 

satisfy the general duty requirements. 

Owners and operators of these 

stationary sources are required in the 

CAA to conduct, in the same manner 

and to the same extent as OSHA's 

general duty clause in section 654 of 

title 29 of the United States Code, these 

activities as a matter of general business 

practice. 

Section 112(r)(3) ofthe CAA requires 

EPA to promulgate, by November 15, 

1992, a list of at least 100 substances 

("regulated substances") that are known 

to cause, or may be reasonably 

anticipated to cause, death, injury, or 

serious adverse effects to human health 

or the environment if accidentally 

released. EPA is required to set 

threshold quantities for each listed 

substance. Under CAA section 112(r)(7), 

the Act requires EPA to promulgate, by 

November 15,1993, reasonable 

regulations and appropriate guidance to 

provide for the prevention and detection 

of accidental releases and for responses 

to such releases. The accident 

prevention regulations will apply to 

stationary sources that have present 

more than a threshold quantity of a 

regulated substance. These regulations 

shall address, as appropriate, the use, 

operation, repair, and maintenance of 

equipment to monitor, detect, inspect, 

and control releases, including training 

of personnel in the use and maintenance 

of equipment or in the conduct of 

periodic inspections. The regulations 

shall include requirements for a risk 

management plan (RMP). The RMP shall 

include a hazard assessment, a 

prevention program, and a response 

program. The proposed rule for the Risk 

Management Program requirements will 

be published in the Federal Register in 

the future. 

The Act establishes a Chemical Safety 

and Hazard Investigation Board to 

investigate (or cause to be investigated) 

chemical accidents at facilities and 

recommend to Congress, Federal, state, 

local authorities, and the public actions 

that can be taken to improve chemical 

safety. Under the Act, EPA is authorized 

to conduct studies related to accidental 

releases, including research on hazard 

assessments, hydrogen fluoride, and air 

dispersion modeling. 

The CAAA also require OSHA to 

promulgate a chemical process safety 

rule (CAAA section 304) to protect 

employees from hazards associated with 

accidental releases of highly hazardous 

chemicals in the workplace. OSHA 

promulgated a final rule (57 FR 6356, 

February 24,1992) requiring a chemical 

process safety management program for 

any process involving a highly 

hazardous chemical at or above a 

specified threshold quantity. The rule 

applies to a list of highly hazardous 

toxic and reactive substances at 

particular threshold quantities, 

flammable liquids or flammable gases in 

quantities of 10,000 pounds or more and 

to the manufacture of explosives and 

pyrotechnics. 

III. List of Substances and Thresholds 

A. Introduction 

The Act requires EPA to promulgate, 

no later than November 15,1992, an 

initial list of at least 100 substances that, 

in the event of an accidental release, are 

known to cause or may reasonably be 

anticipated to cause death, injury, or 

serious adverse effects to human health 

or the environment. An accidental 

release is defined under the Act as "an 

unanticipated emission * * * into the 

ambient air from a stationary source." In 

developing this list, EPA shall use, but 

is not limited to, the list of extremely 

hazardous substances (EHSs) 

promulgated under EPCRA (SARA Title 

III) section 302. 

Congress listed the following 16 

substances to be included in the initial 

list (the Chemical Abstracts Service 

(CAS) Registry number is provided in 

parentheses): 

chlorine (7782-50-5), 

ammonia and anhydrous ammonia 

(7664-41-7), 

methyl chloride (74-87-3), 

ethylene oxide (75-21-8), 

vinyl chloride (75-01-4), 

methyl isocyanate (624-83-9), 

hydrogen cyanide (74-90-8), 

hydrogen sulfide (7783-06-4), 

toluene diisocyanate, represented by: 

—toluene 2,4-diisocyanate (584-84-9) 

—toluene 2,6-diisocyanate (91-08-7) 

—toluene diisocyanate, mixed 

isomers (26471-62-5) 

phosgene (75-44-5), 

bromine (7726-95-6). 

anhydrous hydrogen chloride (7647-01-

0), 

hydrogen fluoride (7664-39-3), 

anhydrous sulfur dioxide (7446-09-5), 

and 

sulfur trioxide (7446-11-9). 
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5104 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

No air pollutant for which a national 

primary ambient air quality standard 

has been established shall be included 

on the list, with the exception of 

anhydrous sulfur dioxide and sulfur 

trioxide, which must be included. No 

substances regulated under title VI of 

the Act as amended shall be included 

on the list. Title VI covers ozone 

depleters, primarily chlorofluorocarbons 

(CFCs) and halons. 

The list of chemicals proposed today 

will, when final, identify stationary 

sources that will be covered by chemical 

accident prevention regulations 

subsequently adopted under section 

112(r) ofthe Act. The list of substances 

is intended to focus accidental release 

prevention efforts on those stationary 

sources and substances that pose 

significant hazards to the community. 

EPA strongly emphasizes, however, that 

the chemicals proposed today for listing 

are not the only substances that may 

pose a threat to communities upon 

release. There are large numbers of 

compounds and mixtures in commerce 

in the United States that in specific 

circumstances could be considered toxic 

or otherwise dangerous; however, it 

would not be feasible to include all such 

substances and circumstances. The 

proposed list represents only the first 

step toward development of an effective 

accidental release prevention effort by 

facilities. Without a preliminary list of 

this kind, it would be more difficult for 

facilities to identify chemical hazards 

with the potential to affect the 

community. This list should serve as a 

focus in initiating prevention efforts; it 

is not a list of all substances that could 

be considered for chemical accident 

prevention. Similarly, the threshold 

quantities being proposed may not 

always represent a level below which no 

hazard exists. Although stationary 

sources will be required to comply with 

the provisions for accidental release 

prevention only if they have listed 

substances in quantities exceeding the 

threshold quantity, it does not mean 

that these substances in smaller 

quantities represent no potential hazard 

to the community. Also, stationary 

sources have a general duty to comply 

and perform activities to prevent and 

mitigate accidental releases regardless of 

the quantity ofthe substance handled 

on site. 

EPA is proposing a list of 100 acutely 

toxic substances, 62 flammable gases 

and volatile flammable liquids, and high 

explosives as a category. Proposed 

threshold quantities for toxic substances 

are based on a ranking method that 

considers each substance's toxicity and 

potential to become airborne and 

disperse. The proposed threshold 

quantity for flammable substances is 

based on the quantity that potentially 

might be involved in a vapor cloud 

explosion. The proposed threshold 

quantity for high explosives is based on 

the quantity that could produce 

potentially lethal blast waves from an 

explosion at a distance of 100 meters. 

The presence of a threshold quantity at 

a stationary source would be 

determined based on the maximum 

quantity in a single process. 

B. Factors Considered in Defining List 

Criteria 

Under CAA section 112(r)(4), the 

factors to be considered in listing 

substances are: (a) The severity of acute 

advesse health effects associated with 

accidental releases of the substance, (b) 

the likelihood of accidental releases of 

the substance, and (c) the potential 

magnitude of human exposure to 

accidental releases of the substance. The 

Act specifies that the Administrator 

shall use, but is not limited to, the list 

of extremely hazardous substances 

(EHSs) under EPCRA (SARA Title III) 

section 302 for purposes of 

promulgating the list. The Act also 

requites that regulations establishing the 

list shall include an explanation of tiie 

basis for establishing the list. 

EPA reviewed a number of existing or 

proposed chemical lists associated with 

other accident prevention, preparedness 

and response programs to evaluate 

criteria for listing regulated substances. 

These lists, which are related to safety 

and the protection of human health and 

the environment, included several EPA 

lists, lists developed by other Federal 

agencies, lists developed under state 

programs, and lists developed under 

international programs. 

The chemical lists reviewed were: 

• The EPCRA (SARA Title III) Section 

302 List of Extremely Hazardous 

Substances 

• The EPCRA (SARA Title III) Section 

313 List of Toxic Chemicals 

• The Comprehensive Environmental 

Response, Compensation, and Liability 

Act (CERCLA) Section 102 Hazardous 

Substances List 

• the Clean Air Act Section 112(b) 

List of Hazardous Air Pollutants 

• "The Department of Transportation's 

(DOT) Toxic by Inhalation Lists 

• OSHA's Proposed List for Process 

Safety Management Regulations1 

• Tiie New Jersey Acute Toxic 

Catastrophe List 

1

 EPA's analysis was based on OSHA's proposed 

rule (55 FR 29150, July 17,1990). OSHA has since 

published a final standard (57 FR 6356, February 

24,1992). 

• The List from the European 

Community's (EC) Seveso Directive 

(subsequently revised) 

• The Delaware Prevention 

Regulations List 

• The National Fire Protection 

Association's (NFPA) Fire Hazard 

Properties of Flammable Liquids, Gases, 

and Volatile Solids 

• Flammable Gases and Volatile 

Flammable Liquids from the DOT 

Hazardous Materials Table 

The criteria used for the development 

of these lists were reviewed to 

determine whether they were related to 

the factors mandated by Congress for list 

development under CAA section 112(r). 

Acute toxicity was generally considered 

in developing these lists of chemicals, 

but some also used flammability and 

explosivity as criteria for regulating 

chemicals. Several lists used a measure 

of dispersibility (equilibrium vapor 

pressure) in combination with acute 

toxicity. Furthermore, some programs 

used, either exclusively or in part, 

criteria rather than lists to define 

covered chemicals. 

The EPCRA (SARA Title III) section 

302 list, the DOT toxic by inhalation 

list, the New Jersey acute toxic 

catastrophe list, the Delaware 

prevention regulations list, and the list 

from the European Community's (EC) 

Seveso Directive are all based on some 

measures of toxicity and the potential 

for a chemical to become airborne. The 

CERCLA list is not based solely on an 

airborne criterion, but rather is based on 

a combination of statutory requirements 

and criteria. OSHA's list is based on a 

review of chemical lists compiled by a 

number of Federal and state agencies 

and other organizations (i.e., EPA, DOT, 

the World Bank, NFPA, the Health and 

Safety Commission of the United 

Kingdom, and the states of Delaware 

and New Jersey) and it includes 

chemicals listed for toxicity and 

reactivity, as well as criteria listings for 

flammability and explosivity. NFPA's 

list was developed by committee and 

includes a compilation of data from 

various sources. Listed chemicals are 

ranked according to their flammability, 

reactivity, and health hazards; the 

flammability rankings are based 

primarily on flash point and boiling 

point. EPA reviewed the DOT 

Hazardous Materials Table, which lists 

materials regulated in transportation, to 

identify flammable substances. The 

Hazardous Materials Table includes 

hazard classes and packing groups 

assigned according to the major hazards 

ofthe substances. For flammable 

liquids, packing groups are assigned 

primarily by flash point and boiling 

point. 
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Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5105 

EPA's review of the CAA section 

112(b) list of hazardous air pollutants 

and of the EPCRA (SARA Title III) 

section 313 list of toxic chemicals 

indicated that both of these lists focus 

on routine emissions rather than 

accidental releases. The CAA section 

112(b) list is aimed at controlling 

routine emissions of hazardous air 

pollutants; the EPCRA (SARA Title III) 

section 313 list focuses on all emissions, 

and is aimed at development of 

information on releases to the 

environment over time. Although both 

of these lists include chemicals that 

have adverse health effects from shortterm exposure, the majority of the 

chemicals listed have the potential for 

producing adverse effects from longterm exposure rather than short-term 

exposure. Adverse health effects from 

long-term exposure are an important 

consideration when dealing with 

routine emissions, but are not the 

primary concern in the event of an 

accidental release. Therefore, EPA 

determined that the CAA section 112(b) 

list and the EPCRA (SARA Title III) 

section 313 list were not of particular 

relevance to the development of the list 

under CAA section 112(r), which 

focuses on the prevention of 

catastrophic accidental releases. 

The factors specified for consideration 

in list development cover a broad 

spectrum (see CAA section 112(r)(4)); 

therefore, the Agency set out to define 

these factors more specifically in 

relation to accidental releases. The 

Agency's definitions are discussed 

below. 

Severity of Acute Adverse Health Effects 

The severity of acute adverse health 

effects can be related to the inherent 

hazards ofthe substances of interest, 

such as the toxicity of a substance 

resulting in lethal effects. Accidental 

releases would most likely lead to shortterm exposure of the public, which 

could cause both immediate and 

delayed toxic effects. Acute adverse 

health effects also could result from 

other inherent hazards, such as the 

flammability of the substance, or 

whether the substance is highly 

reactive. The phenomena associated 

with these hazards could be, for 

example, radiant heat from a chemical 

fire or blast waves from an explosion of 

a chemical. 

As confirmed by a review of death 

and injury events in EPA's Acute 

Hazardous Events (AHE) database, the 

Emergency Response Notification 

System (ERNS) database, the Accidental 

Release Information Program (ARIP) 

database, and other accident data, the 

physical state (liquid, solid, gas) and 

physical/chemical properties (toxicity, 

flammability, explosivity, and volatility) 

of released substances are important 

factors in the actual severity of the 

release. These data show that deaths 

and injuries from accidental releases of 

chemicals are strongly correlated with 

these factors. Because physical state and 

physical/chemical properties are linked 

to severity as well as likelihood and 

potential magnitude of human exposure 

(discussed below), EPA is proposing to 

give these factors substantial weight in 

selecting its proposed list of regulated 

substances. 

Likelihood of Release 

There are many measures and 

surrogates that can be used to define the 

likelihood of an accidental release. The 

likelihood of a chemical being 

accidentally released can be related to 

typical usage and handling scenarios, 

such as equipment commonly used in 

typical facility operations. Ubiquitous 

substances, because of greater handling 

and use, may have a greater potential for 

an accidental release. A history of a 

large number of accidents in the past, 

for example, may be an indicator of an 

existing hazard related to a particular 

substance and its potential to be 

involved in accidental releases in the 

future. Chemicals that are found in large 

volumes at many locations and 

chemicals that are particularly prevalent 

(commodity chemicals, for example) 

may be more likely to be involved in 

accidental releases than small-volume, 

less commonly used chemicals. All of 

these factors may be relevant in 

determining the likelihood of accidental 

release for particular chemical 

substances. However, the Agency also 

believes that there may be limitations to 

reliance on these factors, questions on 

the amount, validity, and reliability of 

existing accident history data, and 

questions about the practicability of 

incorporating factors that may vary from 

site to site (e.g., facility operations or 

type of equipment) in criteria for a 

national list. 

Likelihood can also be related to the 

possibility of the chemical becoming 

airborne and having an effect beyond 

the facility fenceline in the event of an 

accidental release. This likelihood can 

be related to its physical/chemical 

properties. Specific data indicators can 

include physical state (gas, liquid, or 

solid) and vapor pressure. Although it is 

not impossible for solids and nonvolatile liquids to become airborne in an 

explosion, gaseous substances and 

vapors from volatile liquids are more 

likely to be released to air and have an 

effect beyond the facility fenceline. 

Because the chemical and physical 

properties of the substances under 

review are linked to both the likelihood 

and the severity of chemical accidents, 

EPA believes that these two factors 

deserve the greatest weight in 

determining its proposed list of 

substances. EPA solicits comments on 

other factors accounting for severity and 

likelihood of a release that might be 

used to determine the list of substances. 

EPA also solicits comments on the 

availability of data to support the use of 

such factors. 

Magnitude of Human Exposure 

For purposes of today's proposal EPA 

considers the magnitude of human 

exposure associated with accidental 

releases to be related to the severity of 

the health effects (hazards) and the 

likelihood of a release (the likelihood 

that a release will have an effect on the 

population or environment beyond the 

facility fenceline). This definition of 

magnitude of exposure is somewhat 

different from the traditional risk 

assessment definition of human 

exposure, which relates magnitude of 

exposure to the population and 

sensitive environments that may be 

affected by a release from a specific site. 

EPA solicits comments on the relative 

merits of using the Agency's approach 

as a surrogate measure of the magnitude 

of human and environmental exposure 

and requests commenters to submit any 

suggested method for determining 

magnitude of human or environmental 

exposure to accidental releases of 

hazardous substances. 

The Agency recognizes factors that 

might affect the magnitude of human 

exposure could be site-specific or 

accident-specific, and could vary widely 

by location and incident. Proximity to 

population centers and weather 

conditions, for example, may play a role 

in the magnitude of accidental releases. 

EPA believes that these and other sitespecific factors are difficult to use in 

determining national criteria. EPA 

solicits comments on these and any 

other factors and any supporting data 

which may be useful in selecting the list 

of substances. 

EPA has also estimated, through 

analysis of information collected 

through the Accidental Release 

Information Program (ARIP) database for 

some of the listed toxics, the likelihood 

that releases of those toxics reported 

will result in human or environmental 

impacts including injury, 

hospitalization, death, soil 

contamination, vegetation damage, 

groundwater contamination, fire, 

evacuations, and sheltering in place. In 

these events, the actual human or 

environmental exposure level is not 
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5106 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

precisely known and is not predictable 

with any degree of confidence because 

of many site-specific factors that 

influence the result. However, for 

purposes of this proposal, the level of 

severity or degree of hazard for the 

particular substance that generated the 

off-site impact is known such that the 

severity of the health effect and the 

likelihood of release has been used as a 

surrogate for the actual human exposure 

level. EPA requests comments and any 

additional data which could improve 

our assessment of human exposure. 

C. Criteria Options Considered 

The CAA mandates EPA to develop a 

list of substances based on specified 

criteria, namely severity of adverse 

health effects, likelihood of accidental 

releases, and potential magnitude of 

human exposure. The Act also mandates 

the inclusion of 16 substances in this 

list; these substances serve as the 

starting point for the development of the 

full list of regulated substances. The 

Agency identified additional substances 

based on similarities with the mandated 

substances and the selection criteria 

specified in the Act. The options 

considered for the selection criteria 

accounted for the inherent hazards of 

the substances to be listed, as well as for 

the potential these hazards have to 

affect the community in case of an 

accidental release. The hazards 

considered include toxicity, 

flammability, reactivity, explosivity, 

and radioactivity, all of which can result 

in acute effects from short term 

exposures. Substances were identified 

for each of these hazards, but, in 

addition, the Agency considered the 

potential impact that the identified 

substances would have on the 

community in case of a release. Each 

hazard, and its potential to pose a threat 

to the community, was evaluated 

independently of any other hazard, 

because of the difficulties of addressing 

all possible combinations of hazards. A 

group of toxic substances, a group of 

flammable substances, and a group of 

explosive substances are being proposed 

in today's rule for addition to the 16 

mandated substances in the Act. 

EPA is proposing to focus on acute 

effects from short-term exposure to 

toxics as one priority for development of 

this list because these effects are 

believed to be of immediate concern 

beyond the fenceline in case of an 

accidental release. EPA is proposing to 

list 100 acutely toxic substances. EPA is 

also proposing to consider the physical 

hazards of flammable and explosive 

substances because these effects may 

have an impact on the community 

beyond the fenceline in the event of an 

accidental release. For flammable 

chemicals, EPA is focusing on the 

effects of blast waves from vapor cloud 

explosions, because such effects appear 

to have the potential to affect the 

community beyond the fenceline. A list 

of 62 flammable gases and volatile 

flammable liquids is proposed. EPA 

considers commercial high explosives, 

which have the potential to detonate, to 

be the explosive substances with the 

greatest potential to affect the 

community; commercial high explosives 

are proposed for listing as a category. 

EPA also considered, based on analyses 

of accident history data, the relationship 

between past accidental releases of 

toxic, flammable, and explosive 

substances and their associated human 

and environmental effects, as a tool to 

determine the likelihood that future 

events could have similar impacts. EPA 

seeks comments on this approach. EPA 

has also attempted to exclude 

substances from the list that are not in 

production (or imported) or that are not 

handled in commercial quantities. 

1. Toxicity 

To account for the severity of acute 

health effects from accidental releases of 

toxic chemicals, EPA is proposing to list 

a subset ofthe chemicals already . 

identiied as EHSs on the basis of acute 

toxicity (lethality) under EPCRA (SARA 

Title lift) section 302. For purposes of 

criteria for listing, severity of acute 

adverse health effects from toxic 

chemicals was considered to be best 

measured by the concentration or dose 

level that could cause death or serious, 

irreversible health effects after a short 

exposare. Chemicals not on the EHS 

list, but listed under other programs, 

also were reviewed to determine 

whether there were other chemicals that 

should be considered for listing on the 

basis of the EHS acute toxicity criteria. 

EPA believes that using the EHS list 

to identify priority chemicals for the 

accidental release prevention provisions 

is a reasonable approach. The statute 

directed EPA to use the EHS list as a 

starting point for the regulated 

substance list. The EHS list is intended 

to identify chemicals that could cause 

serious irreversible health effects from 

accidental releases because of their 

acute toxicity. The list has been revised 

over the years based on reviews of 

toxicity data. EPA believes that the EHS 

list provides an appropriate basis for 

identifying acutely toxic chemicals for 

the list for accidental release 

prevention. 

Chemicals are listed under section 

302 on the basis of animal test data, 

using the criteria listed below. These 

criteria are discussed in more detail in 

Technical Guidance for Hazards 

Analysis (December 1987), a guidance 

document developed by EPA in 

conjunction with the Federal Emergency 

Management Agency (FEMA) and DOT. 

EPA also included on the EPCRA 

(SARA Title III) section 302 list 

chemicals that are less toxic than those 

meeting these criteria but, because of 

their known toxicity and high 

production volume, may pose a threat to 

the community. 

The acute toxicity criteria are: 

Inhalation LCso£0.5 milligrams per liter 

of air (for exposure time£8 hours), 

or 

Dermal LDSo£50 milligrams per 

kilogram of body weight, or 

Oral LDJO£25 milligrams per kilogram of 

body weight 

where LCso is the median lethal 

concentration, or the concentration in 

air at which 50 percent ofthe test 

animals died, and LDJ0 is the median 

lethal dose, or the dose that killed 50 

percent of the test animals. In the 

absence of LC50 or LD50 data, LCu, or 

LDu, data were used for listing, where 

LCLO is the lethal concentration low, or 

the lowest concentration in air at which 

any test animals died, and LDu> is the 

lethal dose low, or the lowest dose that 

killed any test animals. 

In addition, EPA chose to focus on 

physical state, vapor pressure, and 

accident history in setting criteria 

related to the likelihood of accidental 

releases for toxic chemicals. A vapor 

pressure criterion of 0.5 millimeters of 

mercury (mm Hg) under ambient 

conditions is proposed for toxic liquids. 

This criterion captures most toxic 

substances that have relatively low 

volatility but may still pose an airborne 

hazard in case of an accidental release. 

Congress mandated the listing of 

toluene diisocyanate, which has a 

relatively low ambient vapor pressure; 

therefore, EPA believes it is appropriate 

to set the vapor pressure criterion at a 

level that would include on the list 

other toxic liquids with relatively low 

volatility, similar to toluene 

diisocyanate that also have accident 

history. Chemicals on the EHS list that 

are gases under ambient conditions and 

liquids meeting the vapor pressure 

criterion of 0.5 mm Hg were considered 

for listing. Additional chemicals were 

identified on the basis of high 

production volume and history of 

accidents involving death or injury. 

EPA also analyzed data in the ARIP 

database and attempted to establish a 

relationship between the presence or 

absence of accident prevention 

measures at facilities that have had 

significant accidental releases and the 

probability that the release will result in 
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Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5107 

damaging and environmental effects. 

Using the ARIP data, EPA developed 

estimates of the probabilities that 

releases of those toxic substances 

reported through ARIP would result in 

human or environmental impacts. In 

this way, EPA attempted to measure the 

potential magnitude of the impacts 

resulting from an accidental release of a 

listed toxic substance as it relates to 

certain chemical accident prevention 

requirements at facilities that handle 

these substances. EPA seeks comments 

on which type of data (i.e., relationship 

between accidental releases and human 

and environmental impacts, accident 

history, physical/chemical properties) 

or combination of data could be used to 

evaluate the magnitude of human 

exposure for toxics. 

EPA is focusing on acute toxicity to 

identity toxic chemicals as a priority for 

listing, because acute toxicity is of the 

most immediate concern in an 

accidental release. However, there are a 

number of other possible health effects 

criteria that might be considered at a 

future time for listing hazardous 

substances, including non-lethal acute 

health effects and chronic health effects, 

e.g., lung damage, reproductive and 

developmental toxicity, and 

neurological effects. EPA invites 

comments on methods to evaluate 

substances on the basis of these health 

effects and on how to rank substances 

listed on these bases. 

2. Flammability 

EPA also considered physical hazards 

of chemicals in relation to acute health 

effects. EPA is currently reviewing the 

EPCRA (SARA Title ID) section 302 list 

of chemicals and considering the 

addition of chemicals to that list based 

on explosivity, flammability, and 

reactivity. EPA has published an 

advance notice of proposed rulemaking 

(55 FR 35012, August 27,1990) on 

physical/chemical property criteria for 

adding chemicals to the section 302 list. 

The notice announced the availability of 

technical background documents on the 

potential criteria for listing explosives 

and flammables. The Agency is 

proposing substances for listing today 

based on the analysis conducted in its 

review ofthe EPCRA (SARA Title III) 

section 302 list. The analysis of 

flammables and explosives conducted 

in support of listing under section 302 

has been reviewed by EPA's Science 

Advisory Board. Results of additional 

analysis that may be carried out as a 

result of that review in support ofthe 

EPCRA (SARA Title III) section 302 list 

review will be considered prior to 

publication of a final rule. 

EPA's analysis of historical data on 

accidental releases of flammable 

chemicals indicate that vapor cloud 

explosions may pose the most serious 

hazard from a flammable substance to 

the community. The heat effects of a fire 

involving a flammable liquid or gas, or 

of a fireball from a boiling liquidexpanding vapor explosion (BLEVE), do 

not have a severe impact for as great a 

distance from the source as the blast 

effects of a vapor cloud explosion of the 

same quantity of a flammable substance. 

For example, a 1988 vapor cloud 

explosion at a refinery in Louisiana, 

involving C3 hydrocarbons (primarily 

propane), caused damage up to six miles 

away. Based on the results of EPA 

modeling of flammable hazards and 

analysis of the literature, a clear 

distinction can be made between the 

results for flammable substances that 

boil at temperatures below 

approximately 37° C and higher boiling 

flammable substances. Analysis of other 

classification schemes and regulations 

indicates that flammable gases and 

volatile flammable liquids are the 

flammable materials considered of 

greatest concern by agencies and 

organizations such as DOT, NFPA, and 

EEC. The temperature at which clear 

distinctions in consequences can be 

made, based on modeling techniques, 

corresponds to the temperature at which 

DOT and NFPA have made distinctions 

in categories of flammable materials 

(boiling point below 38°C and flash 

point below 23°C for NFPA 

flammability rating 4; boiling point 

below 35°C and flash point below 23°C 

for DOT packing group I). EPA decided 

to use the criteria used by NFPA for 

flammable gases and liquids with the 

highest degree of hazard (a ranking of 4) 

for flammability to identify flammable 

substances. Flammable liquids with a 

flash point below 73°F (22.8°C) and a 

boiling point below 100°F (37.8°C), as 

well as flammable gases, are included 

under NFPA's highest flammability 

hazard ranking. 

EPA applied the same criteria used for 

toxics when analyzing the likelihood of 

releases related to flammable 

substances. EPA chose to focus on 

physical state, physical/chemical 

properties, and accident history in 

setting criteria related to the likelihood 

of accidental releases of flammable 

substances. The volatility of a 

flammable substance is taken into 

account by the flash point and boiling 

point criteria. No additional substances 

were added after consideration of 

accident history, because the volatility 

criterion already covered all substances 

that otherwise would have been 

proposed. EPA invites comments on 

methods to evaluate substances on the 

basis of these effects and on the ranking 

of these substances. 

EPA examined flammables based on 

accident history, the inherent hazards of 

the substances, and the physical/ 

chemical properties that make them 

likely to be involved in an accident and 

have an effect beyond the fenceline. 

Hazard data, physical/chemical 

properties data, and accident history 

data were used for this basis. However, 

unlike the accident database for toxic 

substances, EPA does not have a 

database from which to estimate directly 

a relationship between the presence or 

absence of accident prevention 

measures at facilities where significant 

accidental releases of flammables have 

occurred and the probability that human 

or environmental impacts will occur. 

Nevertheless, historical data 

demonstrate that flammables can be 

involved in accidents with the potential 

for devastating impacts to the 

community. The Agency believes that 

the accident prevention measures that 

have proven effective at facilities that 

handle toxic substances will be as 

effective at facilities that handle 

flammable substances. EPA requests 

comments and any data that the public 

can provide to directly estimate Uie 

relationship between the presence or 

absence of accident prevention 

measures at facilities where accidental 

releases of these substances have 

occurred and the probability that human 

and environmental impacts will occur. 

EPA also seeks comments on which 

type of data (i.e., relationship between 

accidental releases and human and 

environmental impacts, accident 

history, physical/chemical properties) 

or combination of data could be used to 

evaluate the magnitude of human 

exposure for flammables. 

3. Explosivity 

Explosives are already regulated by 

several agencies and organizations. The 

Bureau of Alcohol, Tobacco, and 

Firearms (BATF) regulates the 

manufacture, processing, use, 

distribution, and storage of explosive 

materials; BATF regulations include 

licensing, pennitting, and recordkeeping 

requirements and requirements for 

storage of explosives. DOT regulates the 

transportation of explosives, and other 

agencies such as OSHA, the Mine Safety 

and Health Administration (MSHA), the 

Department of Defense (DOD), and the 

International Maritime Organization 

(IMO) regulate certain aspects of the 

explosives industry. Many state and 

local governments also have regulations 

regarding licensing and safety 
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5108 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

requirements for explosives. EPA's 

Acute Hazardous Events database and 

other data on accidents show accidents 

involving commercial explosive 

materials that had an impact on the 

neighboring community. BATF 

regulations require that explosives be 

stored at set distances from inhabited 

buildings, highways, and railways, 

limiting the potential impact of an 

accidental explosion. Although 

explosives are currently regulated by 

Federal, state, and local governments, 

these regulations do not uniformly 

address the issue of identifying hazards 

using appropriate hazard assessment 

techniques, designing and maintaining a 

safe facility, and minimizing the 

consequences of accidental releases 

when they do occur. All of these 

elements are to be addressed in the RMP 

program regulations, which are 

intended to help focus on accident 

prevention. Therefore, the Agency 

believes these substances should be 

considered for purposes of list 

development and accidental release 

prevention regulations. 

Blast waves from accidental 

explosions have the potential to cause 

damage to people and property beyond 

the fenceline. EPA considered high 

explosives, low explosives, and blasting 

agents in its analysis of the hazards of 

explosives. High explosives are 

generally defined as those materials that 

detonate if ignited, shocked, or 

subjected to heat or friction. Detonations 

result from chemical reactions that 

proceed at supersonic velocities, 

generating large volumes of high 

pressure gas and heat instantaneously, 

even though no confining vessel or 

structure exists. In an explosion caused 

by a high explosive, the rate of energy 

release is particularly rapid and the 

shock wave has a very short duration 

time. In contrast, low explosives 

deflagrate, or burn relatively slowly in 

comparison to high explosives. A 

deflagration generates lower pressures 

and is less destructive than a 

detonation. Blasting agents are relatively 

low sensitivity explosives which cannot 

be initiated by blasting caps and are 

unlikely to explode except under 

special conditions. DOT defines an 

explosive as "any substance or article, 

including a device, which is designed to 

function by explosion (i.e., an extremely 

rapid release of gas and heat) or which, 

by chemical reaction within itself, is 

able to function in a similar manner 

even if not designed to function by 

explosion * * *" High explosives are 

classified by DOT in Division 1.1, 

defined as explosives that have a mass 

explosion hazard, where a mass 

explosion hazard is one that affects 

almost the entire load instantaneously. 

Low explosives, Division 1.3 under 

DOT, are defined as explosives that 

have a fire hazard and either a minor 

blast hazard or a minor projection 

hazard or both, but not a mass explosion 

hazard. Blasting agents, Division 1.5, are 

defined as explosives that have a mass 

explosion hazard but are so insensitive 

that there is very little probability of 

initiation or of transition from burning 

to detonation under normal conditions 

of transport. 

EPA's analysis for revisions to the 

EPCRA (SARA Title ID) section 302 list 

indicates that blast waves caused by the 

detonation of commercial high 

explosives could potentially have an 

impact on the community. However, 

EPA's analysis indicates that low 

explosives, which primarily pose a fire 

hazard rather than a mass explosion 

hazard, are less likely to cause a 

catastrophic event when compared to 

the same quantity of high explosives. 

The deflagration or burning of a low 

explosive generates lower pressures and 

is less destructive than the detonation of 

a high explosives, although the Agency 

recognizes that it may be possible for 

some low explosives to detonate under 

unusual conditions, with effects similar 

to the detonation of a high explosive. 

Another key distinction between 

categories of explosives is the likelihood 

of initiation of an explosion. Blasting 

agents, for example, have a mass 

explosion hazard, but it is much more 

difficult to set off an explosion of a 

blasting agent, making them less likely 

to explode accidentally. The Agency 

recognizes, however, that it is still 

possible for a blasting agent to detonate 

accidentally under some circumstances. 

In this case, the distinctions between 

blasting agents and high explosives may 

not be apparent; effects on the 

community could be felt from 

explosions of both types of explosives. 

EPA examined explosives based on 

accident history, the inherent hazards of 

the substances, and the physical/ 

chemical properties that make them 

likely to be involved in an accident and 

have an effect beyond the fenceline. 

Hazard data, physical/chemical 

properties data, and accident history 

data were used for this basis. However, 

unlike the accident database for toxic 

substances, EPA does not have a 

database from which to estimate directly 

a relationship between the presence or 

absence of accident prevention 

measures at facilities where significant 

accidental releases of explosives have 

occuia-ed and the probability that human 

or environmental impacts will occur. 

Nevertheless, historical data 

demonstrate that explosives can be 

involved in accidents with the potential 

for devastating impacts to the 

community. The Agency believes that 

the accident prevention measures that 

have proven effective at facilities that 

handle toxic substances will be as 

effective at facilities that handle 

explosive substances. EPA requests 

comments and any data that the public 

can provide to directly estimate the 

relationship between the presence or 

absence of accident prevention 

measures at facilities where accidental 

releases of these substances have 

occurred and the probability that human 

and environmental impacts will occur. 

EPA also invites comments on methods 

to evaluate substances on the basis of 

these effects and on the ranking of these 

substances. EPA also seeks comments 

on which type of data (i.e., relationship 

between accidental releases and human 

and environmental impacts, accident 

history, physical/chemical properties) 

or combination of data could be used to 

evaluate the magnitude of human 

exposure for explosives. 

4. Reactivity 

In its analysis for EPCRA (SARA Title 

III) section 302 list revisions, EPA is 

currently working to identify 

approaches for evaluating the hazards 

associated with other types of 

substances that may have explosive 

properties, e.g., unstable substances 

such as certain peroxides. To evaluate 

the hazards of these substances, a 

number of factors must be considered, 

such as the energy of reaction and 

whether a probable or possible result of 

the decomposition of such substances 

would be a deflagration, with heat 

radiation the primary consequence, or a 

detonation, with blast waves the 

primary consequence. EPA also has 

examined the chemicals that are highly 

reactive with air or water; identifying 

common characteristics or specific 

properties that cause chemicals to be so 

reactive with air or water as to pose a 

hazard to the community requires 

additional study. For example, 

chemicals that are reactive with water 

may react to produce a flammable gas, 

creating a fire or explosion hazard, or to 

produce a toxic gas, or they may 

decompose explosively on contact with 

water; the consequences of these 

reactions would be very different. At 

present, EPA is attempting to evaluate 

the hazards of reactive chemicals and to 

develop an adequate technical basis to 

determine the potential effects on the 

community. EPA is investigating, for 

example, computer models that estimate 

heats of reaction, and the possible use 

ofthe heats of reaction to compare the 
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Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5109 

effects of an explosion of an unstable 

substance to the effects of an explosion 

of trinitrotoluene (TNT). This 

methodology would only be appropriate 

for substances that detonate, which 

appears to be unlikely for many 

unstable substances. Unstable and 

reactive substances will be considered 

for listing for accidental release 

prevention if the evaluation indicates 

potential consequences involving the 

community. Thus, any decision relating 

to this type of hazard will be deferred 

pending additional Agency review. EPA 

requests comments on methods that 

might be used to evaluate the potential 

consequences of accidents involving 

reactive substances. 

5. Radioactivity 

EPA is requesting information to 

determine the need and appropriateness 

of listing radionuclides under this 

proposed rulemaking. There are several 

issues that the Agency considers of 

importance in making such a 

determination. Do any or all 

radionuclides at facilities not licensed 

by the Nuclear Regulatory Commission 

(NRC) pose risks of severe health effects 

in case of an accidental release? If some 

radionuclides were listed, should they 

be listed a class of substances, or is it 

more appropriate to prioritize their 

hazards and list specific radionuclides 

of concern? What specific approaches 

could be taken to develop a 

methodology that sets thresholds for 

radionuclides that would represent 

equivalent hazards to those posed by 

other substances listed under this rule? 

Is the volatility of radionuclides 

relevant to their potential to be 

released? The Agency is interested in 

obtaining information on the universe of 

facilities potentially affected by listing 

radionuclides; the baseline considered 

by the Agency is listing of radionuclides 

as a class with levels similar to those 

established for NRC-licensed facilities 

under NUREG 1140, A Regulatory 

Analysis on Emergency Preparedness 

for Fuel Cycle and Other Radioactive 

Materials Licensees (NRC-licensed 

facilities are exempt from these 

provisions under the CAA 

amendments). Finally, the Agency 

requests comments on how regulations 

that may be in place for the accidental 

release prevention of radionuclides at 

the Federal, state, or local levels would 

interact with the accident prevention 

requirements applicable to these 

substances. 

D. List of Substances 

1. Proposed List 

EPA is proposing a list of 100 toxic 

chemicals based on the criteria 

discussed above and the list of 

chemicals mandated for inclusion. EPA 

is also proposing a list of 62 flammable 

gases and volatile flammable liquids. 

The lists of toxic and flammable 

chemicals are set forth in §67.130 ofthe 

proposed rule. EPA is also proposing 

the commercial explosives in Division 

1.1 (explosives with a mass explosion 

hazard), as defined by DOT; individual 

commercial explosives are not included 

on the proposed list. In proposing this 

list, EPA considered the factors 

specified in the Act: severity of acute 

adverse health effects associated with 

accidental releases, the likelihood of 

accidental releases, and the potential 

magnitude of human exposure to 

accidental releases (albeit not directly as 

function of factors such as population 

exposed). As noted above, each hazard 

was evaluated independently. The final 

list adopted by the Agency may consist 

of a combination of any of these 

substances. Substances will be placed 

on the final list according the statutory 

criteria and based upon public comment 

and additional information provided by 

the public or developed by the Agency 

as a result of public comment. 

a. Toxic Substances. All of the 93 

EHSs on the list of 100 toxic chemicals 

proposed for listing are reported to be 

toxic by inhalation; inhalation toxicity 

would be expected to be the greatest 

hazard to the public from an accidental 

release to air. The list includes the 

following categories of chemicals: 

o Gases on the EHS list. The list 

includes 22 gases that meet the toxicity 

criteria based on their presence on the 

EHS list and meet the criteria for 

likelihood of accidental releases based 

on their physical state and the fact that 

they are in commercial production. Two 

other gases meeting these criteria, ozone 

and nitrogen dioxide, have primary 

national ambient air quality standards 

and are, therefore, excluded from the 

list by statute. 

o Liquids on the EHS list with vapor 

pressure of 0.5 mm Hg or greater. There 

are 65 liquids that meet the toxicity 

criteria by virtue of inclusion on the 

EHS list and meet the criteria for 

likelihood of accidental releases because 

their vapor pressure under ambient 

conditions is 0.5 mm Hg or higher, and 

they are in commercial production. Two 

additional chemicals meeting these 

criteria, methyl vinyl ketone and 

methacryloyl chloride, were not 

included because the toxicity data used 

for listing are based on inhalation 

studies that may contain flawed 

scientific methods. EPA requested 

comments on these two chemicals in a 

proposed rule to delete several 

chemicals from the EHS list. No 

comments were received, and no 

additional toxicity data were obtained; 

therefore, these chemicals were not 

deleted from the EHS list. However, 

EPA does not believe it is appropriate to 

include methyl vinyl ketone and 

methacryloyl chloride on this proposed 

list based on toxicity data that may be 

questionable. 

o Other liquids on the EHS list. 

Toluene 2,4-diisocyanate (584-84-9) 

and toluene 2,6-diisocyanate (91-08-7) 

are included on the list because 

Congress mandated the listing of 

toluene diisocyanate. Four liquids from 

the EHS list are included because they 

are produced in high volumes and have 

been involved in a number of accidents 

in the past in which deaths or injuries 

have occurred, based on information 

from several databases, including the 

AHE, ERNS, and ARIP databases; 

therefore, they meet the likelihood 

criteria, although they have ambient 

vapor pressures less than 0.5 mm Hg, 

These chemicals (CAS numbers in 

parentheses) are: nitrobenzene (98-95-

3), parathion (56-38-2), phenol (108-

95-2), and sulfuric acid (7664-93-9). 

(EPA is proposing to include phenol in 

liquid form only; phenol is a lowmelting solid under ambient conditions 

but is frequently stored and shipped as 

a liquid above its melting point.) The 

accident history data and high 

production volume indicate that these 

substances pose a great risk to human 

health and the environment from 

accidental releases. 

Releases to air are reported for all of 

these substances in EPA's AHE 

database, even though their vapor 

pressure is less than 0.5 mm Hg. 

Sulfuric acid is one of the most 

frequently reported chemicals involved 

in incidents with death and injury in 

EPA's AHE database, and the most 

frequently reported in all accidents; in 

addition, it is the highest-volume 

chemical in commerce in the U.S. The 

AHE database includes nearly 200 

reports of incidents involving sulfuric 

acid, more than half of them involving 

releases to air and 60 of them involving 

deaths or injuries. Air releases were 

reported in more than half of the 

incidents with deaths or injuries, 

including four where explosions were 

reported. The ARIP database includes 

nearly 150 reports for sulfuric acid. 

Migration of sulfuric acid beyond the 

facility boundaries was reported in a 

significant number (32) of incidents. In 
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5110 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

two of these cases, migration of sulfuric 

acid as a vapor or gas was reported. 

For phenol, the AHE database 

includes reports of 24 incidents, with 

one-third of them involving releases to 

air. Deaths or injuries were reported in 

five phenol incidents, with air releases 

reported in two of them. The ARIP 

database includes 10 reports for phenol, 

with migration beyond the fenceline 

reported in four of them. In two of these 

cases, migration beyond the fenceline 

was reported for phenol vapor. 

Parathion incidents were reported 11 

times in the AHE database, with releases 

to air reported in most of them, and 

deaths or injuries reported in eight of 

them. Recent regulations have restricted 

the use of parathion; as a result of the 

restrictions, the likelihood of accidents 

involving parathion may decrease. EPA 

requests comments on whether 

parathion should be included on the list 

of regulated substances or whether 

current regulations are sufficient to 

prevent accidents involving parathion. 

For nitrobenzene, there were four 

incidents reported in the AHE database, 

all with releases to air. Two ofthe 

incidents involved deaths or injuries, 

with a large number of deaths reported 

in one incident, in which an explosion 

and fire were reported. 

• Non-EHSs. Two gases proposed for 

listing, methyl chloride (74-87-3) and 

vinyl chloride (75-01—4), are not on the 

EHS list but are mandated for listing. 

Both of these chemicals have a history 

of accidents involving death or injury. 

Both of these chemicals are also highly 

flammable and would meet the listing 

criteria for flammability. No other gases, 

chlorine dioxide (10049-04-4) and 

cyanogen chloride (506-77—4), were 

recommended for listing by OSHA, and 

are included because of their toxicity, 

potential for airborne release, and 

production volume. Chlorine dioxide 

appears to meet the criteria for "other" 

chemicals on the EHS list, based on 

toxicity and production volume. 

Cyanogen chloride does not strictly 

meet the listing criteria, primarily 

because the available data are for 

extremely short exposure periods; 

however, data indicate that this 

substance is highly toxic and would 

probably meet the EHS criteria if 

adjustments were made for duration of 

exposure. EPA concluded that listing is 

appropriate, based on available data. 

Congress mandated the listing of both 

anhydrous ammonia and ammonia; the 

EHS list includes only one listing for 

ammonia, with no form specified. EPA 

is proposing to include both ammonia 

(anhydrous) (7664-41-7) and 

ammonia—aqueous (solutions with total 

ammonia concentration in water of 20 

percent by weight or greater). The 

concentration cut-off was chosen so that 

commonly used commercial solutions of 

ammenia would be covered. 

Coagress also mandated the listing of 

toluene diisocyanate, without specifying 

an isomer; EPA is proposing to list 

tolueae diisocyanate (unspecified 

isomer) (26471-62-5), which is not on 

the EHS list, in addition to toluene 2,4-

diisoeyanate (584-84-9) and toluene 

2,6-dIsocyanate (91-08-7), which are 

EHSs, The TSCA Inventory includes 

these three listings for toluene 

diisocyanate (and no other listings). 

Including unspecified isomers on Uie 

list should help to ensure that all forms 

of toluene diisocyanate are covered, in 

conformance with Uie intent of 

Congsess. 

Hydrochloric acid (solution, 

concentration 25 percent by weight or 

greater) (7647-01-0), which is not an 

EHS, is proposed for listing, in addition 

to anhydrous hydrogen chloride, which 

is an EHS. The concentration cut-off of 

25 percent is intended to cover 

commonly-used commercial solutions 

of hydrochloric acid; solutions of 

hydrochloric acid in these 

concentrations could release hydrogen 

chloride gas in the event of a spill. 

Listing of the solution is proposed on 

the basis of its potential to release 

hydrogen chloride, high volume use, 

and accident history. Hydrochloric acid 

is one of the most frequently reported 

chemicals in death and injury events 

and in all events in the AHE database; 

the ARIP database also includes many 

reports of incidents involving 

hydrochloric acid. 

b. Flammable Substances. The 

proposed list of 62 flammable 

substances includes 43 flammable gases 

and 19 volatile flammable liquids that 

meet the criteria for NFPA's highest 

flammability hazard ranking. These 

substances were identified from NFPA's 

Properties of Flammable Liquids, Gases 

and Volatile Solids and DOT's 

Hazardous Materials Table; in addition, 

there was evidence of production of 

these substances in commercial 

quantities. EPA is not proposing to 

cover any of these substances when they 

are used solely for facility consumption 

as fuel. Two additional chemicals that 

met the criteria for listing were 

excluded from the list because they are 

covered under title VI of the Act as 

amended. Some ofthe substances listed 

on the basis of toxicity also meet the 

flammability criteria; they are listed as 

toxic substances, however, and were not 

considered for listing as flammables. 

c. Explosive Substances. EPA is 

proposing to include all explosives that 

meet the criteria specified by DOT for 

Division 1.1 (55 FR 52402, December 

21,1990; 49 CFR part 172), which are 

based on the United Nations 

Recommendations on the Transport of 

Dangerous Goods. High explosives are 

proposed for listing as a class, rather 

than as individual substances, because 

explosives are usually mixtures or 

formulations rather than specific 

chemicals. An individual chemical 

could be a component ofa high 

explosive or a low explosive, or could 

be non-explosive, depending on various 

factors; e.g., particle size, concentration, 

and other components of the 

fonnulation. EPA is not proposing to list 

any individual explosive substances. 

a. Toxic Substances Not Proposed for 

Listing. Several toxic substances that 

initially appeared to meet the listing 

criteria are not proposed for listing at 

this time. These substances include two 

that were listed as EHSs on Uie basis of 

toxicity data based on inhalation studies 

that may contain flawed scientific 

methods. These two substances, methyl 

vinyl ketone (78-94-4) and 

methacryloyl chloride (920-46-7), are 

not proposed for listing today because of 

the questionable nature of the toxicity 

data. Two additional substances on the 

EHS list Uiat did not meet the vapor 

pressure criterion were considered for 

listing because they have been involved 

in a number of accidents with death or 

injury. These substances, chlordane 

(57-74-9) and tetraethyllead (78-00-2), 

are not proposed for listing because 

recent regulatory developments make it 

unlikely that they will be produced in 

commercial quantities in the future; 

therefore, they are unlikely to be 

involved in potentially catastrophic 

accidents. EPA requests comments on 

the exclusion of these chemicals from 

the proposed list of substances. 

2. Other List Options 

As discussed above, the Agency is 

proposing a list of substances comprised 

of three distinct categories: toxics, 

flammables, and explosives. The 

substances listed under each category 

conform to the discussed criteria for the 

particular hazard it presents, and reflect 

a measure of likelihood of off-site 

impacts in case of accidental release. 

Because these categories have been 

developed independently of each other, 

the Agency may choose, at Uie time of 

final promulgation, to adopt any of 

these hazard options, or any individual 

substance covered by these options 

based on public comment and any 

additional information provided or 

developed by the Agency as a result of 

public comment. 

In addition to those options that 

would be variations of the proposed list 
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of substances (e.g., toxics only; toxics 

and flammables only; a subset including 

toxics, flammables and explosives), the 

Agency also considered an additional 

option for the list of regulated 

substances that would meet the 

statutory criteria. This option is 

discussed below. The Agency requests 

comments on any variation of the 

proposed list, as well as on the 

additional option for comment. 

Entire EHS List. EPA considered Uie 

option of adopting Uie entire list of 360 

chemicals regulated under EPCRA 

(SARA Title III) section 302 as the list 

of toxic chemicals. These chemicals are 

listed on the basis of acute toxicity, and, 

therefore, meet the criterion of severity 

of acute health effects. Since this list 

was adopted in 1986, toxicity data for 

many of the chemicals have been 

reviewed or are currently under review, 

data on other properties have been 

collected and updated, and other 

chemicals have been reviewed for 

possible addition to the list. However, 

Uie EHS list is based solely upon acute 

toxicity for most of the substances, 

without any consideration of their 

volatility, which relates to the 

likelihood of that substance being 

involved in a catastrophic airborne 

accidental release that carries beyond 

the facility fenceline. For the initial list 

of substances for accidental release 

prevention, EPA proposes to focus on 

those toxic chemicals posing the 

greatest potential threat to Uie 

community from airborne releases. In 

this way, the initial list-will reflect the 

statutory criteria of likelihood and 

magnitude of release. The EHS list 

includes a number of solids and nonvolatile liquids Uiat, although they meet 

the toxicity criteria, are expected to be 

much less likely to have an effect 

beyond Uie fenceline in Uie event of an 

accidental release than those EHSs Uiat 

are gases and volatile liquids. 

E. Threshold Quantities 

Under CAA section 112(r)(5), EPA 

must establish threshold quantities for 

each substance at the time of listing. 

The threshold quantity should take into 

account the toxicity, reactivity, 

volatility, dispersibility, combustibility, 

or flammability of Uie substance, and 

the amount of the substance known or 

anticipated to cause death, injury, or 

serious adverse human health effects. 

Substances used by farmers as 

agricultural nutrients may be assigned 

greater threshold quantities or 

exempted. Two issues related to 

threshold quantities were considered: 

Development of an appropriate 

threshold quantity for triggering the risk 

management prevention regulations and 

development of a method for 

determining whether a stationary source 

has present a quantity of a listed 

chemical greater than the threshold 

quantity. The Agency does not consider 

any thresholds to be a precise measure 

ofa "safe" level; no such level can be 

determined. The risk posed by any 

chemical release depends on the 

particular circumstances at the time of 

the release; for example, releases of the 

same quantity of Uie chemical may pose 

very different threats depending on the 

location of a facility, weather at Uie time 

of the release, the elevation of the 

source of the release (e.g., a release from 

a smokestack versus a ground level 

release), and the pressure and 

temperature of the substance, among 

other factors. 

1. Review of Threshold Methodologies 

In developing threshold quantities, 

the reporting thresholds associated with 

Uie other lists considered and the 

methods used to develop them were 

reviewed. This review is discussed 

below. 

Delaware Methodology. The Delaware 

thresholds for toxic chemicals were 

determined on the basis of dispersion 

modeling and a combination of toxicity 

and vapor pressure; the Delaware 

"Sufficient Quantity" (SQ) for a toxic 

chemical is defined as the quantity that 

would create a potentially lethal 

concentration at the facility boundary if 

released over a period of one hour. The 

thresholds are calculated based on an 

assumption of a 100-meter distance to 

Uie fenceline. If the distance at a facility 

is greater, the threshold is adjusted 

upward. 

For flammable materials, Delaware 

provides a calculation method for 

determination of the SQ based on a 

comparison with propane. The 

Delaware calculation is based on the 

release rate calculated for propane as 

sufficient to cause death or permanent 

disability from heat radiation resulting 

from a fireball at a distance of 100 

meters from the point of release. SQs for 

other flammable substances are 

calculated based on Uie properties of Uie 

substances compared to the properties 

of propane. Thresholds can be adjusted 

upward for fenceline distances greater 

than 100 meters, as for toxicsi 

Delaware specifically excludes 

commercial explosives from its list. For 

potentially explosive chemicals that are 

not commercial explosives, SQs are 

determined by relating explosion energy 

for a given mass of material to an 

equivalent mass of TNT. The scaling 

law, which relates blast overpressure, 

distance, and mass of TNT, was used to 

calculate SQs. The SQ for a reactive 

substance was the quantity calculated to 

create an overpressure of 2.3 pounds per 

square inch (psi) at a distance of 100 

meters. 

New Jersey Methodology. New Jersey 

thresholds for toxic chemicals are set 

based on dispersion modeling and 

mortality curves; a Registration Quantity 

(RQ) is the quantity Uiat will produce 

one fatality in a location with 10,000 

people per square mile. New Jersey does 

not currently list flammable or 

explosive substances. 

ORC Methodology. The methodology 

recommended by the Organization 

Resources Counselors (ORC) for the 

development of threshold quantities for 

toxic chemicals, presented by ORC to 

OSHA in public hearings, was also 

reviewed. This method uses dispersion 

modeling, assuming the total quantity of 

the substance released immediately 

becomes airborne, to determine Uie 

quantity of a toxic substance Uiat would 

lead to a concentration that could cause 

death or permanent disability at a 

distance of 100 meters from the point of 

release from a one-hour exposure. 

For reactive chemicals, tne threshold 

methodology recommended by ORC was 

the same as that used by Delaware to 

develop SQs for explosive chemicals, 

described above. 

EHS TPO Methodology. The threshold 

planning quantities (TPQs) developed 

for EHSs are based on a ranking of the 

EHSs according to their potential to 

become airborne, dispersion potenUal, 

and toxicological properties, with 

adjustments based on chemical 

reactivity and other factors. To develop 

the TPQs for EHSs, the Immediately 

Dangerous to Life and Health (IDLH) 

level developed by the National 

Institute of Occupational Safety and 

Health (NIOSH), or an approximation of 

Uie IDLH based on animal toxicity data, 

was used as an index of toxicity. 

Physical state and volatility were used 

to derive an index of the chemical's 

potential tb become airborne and 

disperse. The two indices were 

combined to produce an overall risk 

"ranking factor" defined as IDLH/V, 

where V is the index of potential to 

become airborne and disperse. TPQs 

were assigned to groups of EHSs 

according to their relative ranking. 

The index of potential to become 

airborne and disperse (V) was derived 

based on physical state and volatility. 

For EHSs that are gases under ambient 

conditions, V was assumed to have a 

value of 1, indicating that in an 

accidental release, the total quantity of 

chemical involved in Uie release could 

become airborne. For liquids, V was 

calculated by estimating the rate of 

volatilization from a pool (assumed to 
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5112 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

be one centimeter in depth) on a flat, 

non-absorbing surface using equations 

presented in Attachment 1 of the 

Interim Final Rule of November 17, 

1986, listing EHSs under EPCRA (SARA 

Title III) section 302 (51 FR 41580). 

Liquids were assumed to be at their 

boiling point, and all liquids were 

assumed to have the same density as 

water. A mass transfer coefficient was 

estimated by reference to water. Because 

of these assumptions, the only variables 

used in the calculation of V were the 

molecular weight and boiling point of 

the liquid. 

The EHSs were ranked according to 

the ranking factor IDLH/V and assigned 

TPQs of 1,10,100, 500,1,000, or 10,000 

pounds based on order of magnitude 

ranges in the ranking factor. The TPQs 

assigned based on the ranking factors 

were reviewed, and changes were made 

based on other toxicity data, rapid 

absorption, chemical reactivity, and 

consideration of specific handling, 

formulation, and use information. 

2. Proposed Threshold Methodology 

Relative Ranking for Toxic Chemicals. 

To set thresholds for toxic chemicals, 

EPA is proposing to use a ranking 

method similar to that used in 

developing the TPQs for EHSs, as 

described above, modified to reflect the 

different purposes of thresholds under 

this rulemaking; i.e., under EPCRA 

(SARA Title III) section 302, thresholds 

only trigger reporting by facilities to 

state and local planners, while under 

CAA section 112, facilities with listed 

substances in quantities exceeding the 

threshold will be required to comply 

with prevention requirements, such as 

the development of risk management 

plans. Using the revised threshold 

methodology, a ranking factor based on 

toxicity and potential to become 

airborne and disperse was derived as 

described above. In some cases, revised 

toxicity data or IDLH values were used. 

Thresholds were assigned by order of 

magnitude ranges in the ranking factor; 

threshold quantity categories are as 

follows: 500 pounds, 1,000 pounds, 

5,000 pounds, and 10,000 pounds. The 

threshold quantities selected are, at the 

minimum level of 500 pounds, 

representative of drum-size containers, 

and, at the maximum level of 10,000 

pounds, consistent with reporting 

requirements already in place for 

EPCRA (SARA Title IH) under sections 

311-312 and 302. Under EPCRA (SARA 

Title III) sections 311-312, facilities 

must submit material safety data sheets, 

chemical lists, or inventory reports on 

hazardous chemicals to state and local 

agencies at a threshold for most 

chemicals of 10,000 pounds. Under 

EPCRA (SARA Title ffl) section 302, Uie 

maximum TPQ for EHSs is 10,000 

pounds; the presence of a TPQ of an 

EHS requires facilities to notify state 

and local planners. 

A relative ranking method to assign 

thresholds has advantages over 

developing substance-specific 

thresholds based on dispersion 

modeling because airborne dispersion 

mode&ng involves many site-specific 

and accident-specific parameters, 

including Uie distance from the source 

to the community or fenceline, the 

conditions under which the chemical is 

handled (e.g., temperature and 

pressure), the topography ofthe area 

around the facility, and meteorological 

conditions at the time of Uie release. 

The Agency's analysis showed that 

assumptions made for modeling cause 

wide variations in the results. In 

additien, the relative ranking takes into 

account both toxicity and volatility. Air 

dispersion modeling alone does not take 

into account Uie potential for a 

substance to become airborne. This 

relative ranking method also is 

consistent with Uie methodology for 

assigning TPQs under EPCRA (SARA 

Title III) section 302. 

This methodology has been appUed to 

develop thresholds for additional 

substances that would be listed if EPA 

chose the option, discussed above, of 

adopting Uie entire list of EHSs 

regulated under EPCRA (SARA Title III) 

section 302. Refer to Uie technical 

background documents in the docket for 

more mformation on thresholds for 

EHSs sot proposed for listing. 

Thresholds have been developed using 

this methodology for Uie four toxic 

chemicals discussed previously, that 

appeared to meet the listing criteria but 

have not been proposed for listing 

because of questionable toxicity data or 

because they are not expected to be 

produced in commercial quantities in 

the future. The thresholds for these 

chemicals would be: chlordane (57-74-

9), 5,000 pounds; methacryloyl chloride 

(920-46-7), 500 pounds; methyl vinyl 

ketone (78-94-4), 500 pounds; 

tetrae&yllead (78-00-2), 1,000 pounds. 

Threshold Methodology for 

Flammable Substances. EPA's analysis 

ofthe hazards of flammable chemicals 

indicates that the greatest hazard to the 

public from these substances is from 

vapor cloud explosions. Historical data 

indicate that vapor cloud explosions are 

unlikely for vapor clouds containing 

quantities less than 10,000 pounds. The 

quantity in a vapor cloud resulting from 

an accidental release of a flammable gas 

or volatile flammable liquid could vary 

greatly depending on site-specific and 

accident-specific conditions, as well as 

properties of the chemical released. 

Because it would be difficult to set 

chemical-specific thresholds based on 

all these factors, EPA is proposing to set 

Uie thresholds for all the listed 

flammable substances at 10,000 pounds. 

EPA believes that this threshold is 

conservative and protective of Uie 

public because Uie vapor cloud resulting 

from a release of 10,000 pounds would 

probably contain a quantity less than 

10,000 pounds, even though all of Uie 

listed flammable substances are gases or 

volatile liquids. Establishing one 

threshold for all the flammable 

substances on Uie list also simplifies Uie 

regulatory process. 

Threshold Methodology for 

Explosives. EPA's analysis of explosives 

indicates that a blast wave overpressure 

of 3.0 psi from a detonation could have 

potentially lethal effects in the 

community beyond the fenceline of a 

facility. This overpressure level could 

cause serious structural damage to 

buildings, lead to serious wounds from 

flying glass, and potentially cause 

eardrum rupture. EPA used Uie scaling 

law of distances, which relates quantity 

of explosive material and distance for a 

given overpressure, to estimate the 

quantity of high explosives that would 

produce an overpressure of 3.0 psi at a 

distance of 100 meters in the event of 

a detonation. Based on this calculation, 

EPA decided to set Uie threshold for 

high explosives at 5,000 pounds. 

Although individual high explosives 

may vary in their explosive power, the 

variations are not very great; high 

explosives function by detonation and 

produce similar results for a given 

weight. EPA believes, therefore, Uiat it 

is appropriate to apply one threshold 

quantity to all high explosives. This is 

consistent with the approach used by 

BATF to set storage distances for high 

explosives; BATF uses one table of 

distances for all high explosives. EPA 

believes that this threshold will apply 

primarily to manufacturers of high 

explosives, who have larger quantities 

available on site with Uie potential for 

catastrophic releases. Users of 

explosives (e.g., for industrial uses, 

construction, or mining) would 

probably not have enough high 

explosives present at one time to meet 

this threshold; lower quantities on site 

and existing regulations would reduce 

the likelihood of catastrophic events at 

these facilities. 

3. Other Threshold Options 

The Agency's proposed options for 

Uie threshold quantity methodology 

relate to the physical/chemical 

properties of Uie substances and the 

specific hazard that each substance 
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Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5113 

presents (i.e., toxicity, flammability, 

explosivity). EPA recognizes however, 

that Uie impact of a release in a 

particular instance may be greater or 

lesser depending upon site-specific 

considerations and that there may be 

other factors that can be accounted for 

in a methodology to determine a 

threshold quantity. These other factors 

may include industry class or facility 

type in which a particular chemical is 

typically handled or used. For example, 

a threshold quantity for a particular 

chemical could be adjusted if it is 

typically handled at elevated 

temperatures and pressures. Other 

factors Uiat might be considered under 

this approach include typical SIC codes 

in which a particular chemical is 

handled, typical population density and 

sensitivity around types of facilities that 

handle a particular chemical (e.g., a 

chemical may be typically used at 

remote locations, far from dense 

population centers or sensitive 

ecosystems), or process type in which a 

chemical is typically involved. The 

advantages of this approach would be 

that it would more specifically tailor 

threshold quantities based on common 

use patterns of a substance. The 

disadvantage would be that this 

approach would not apply to ubiquitous 

chemicals that are used in a wide 

variety of applications, such as chlorine, 

ammonia, and sulfuric acid, which are 

also chemicals that, according to 

Agency data, are frequently involved in 

accidental releases and incidents 

involving deaths and injuries. A greater 

disadvantage to this approach is that the 

intrinsic hazard of a chemical will still 

be present even when it is used outside 

ofa "typical" scenario; it would not 

account for the potential for chemical 

accidents in all possible handling or use 

scenarios. Also, based on current data 

limitations, EPA believes it is not 

feasible to develop a methodology that 

adopts a typical use factor and that 

would still be applicable uniformly 

nationwide. The Agency requests 

comments on methods or supporting 

data which would permit the use of the 

aforementioned factors (or other factors) 

to establish threshold quantities. 

In developing the proposed threshold 

methodologies, Uie Agency also 

considered four additional options, 

which are discussed below. Three of 

these methodologies are based on 

intrinsic properties of each substance 

(i.e., physical/chemical properties, 

toxicity, explosivity, flammability). The 

fourth option is the adoption of 

thresholds already developed by 

another agency. EPA requests comments 

on these methodologies. 

Vapor Quantity Method (Toxics). EPA 

considered a method similar to that 

recommended by ORC for development 

of threshold quantities for toxics, as 

described above. To derive threshold 

quantities by this method, a 

concentration level equal to the IDLH or 

its equivalent was assumed to be 

reached at a distance of 100 meters from 

the source of the release. A release rate 

that would produce that concentration 

level at 100 meters was calculated using 

air dispersion modeling techniques. The 

dispersion modeling used was based on 

equations presented in Technical 

Guidance for Hazards Analysis (EPA, 

FEMA, and DOT, 1987). For Uie 

calculations, moderate conditions ofa 

wind speed of 10 miles per hour (4.4 

meters per second), atmospheric 

stability D, and urban conditions were 

assumed. The duration of the release 

was assumed to be 30 minutes, and a 

quantity was calculated by multiplying 

the release rate by the duration. 

Threshold quantities were assigned 

based on the calculated quantity, with 

500 pounds as the lower bound and 

10,000 pounds as the upper bound. 

Refer to the technical background 

documents in the docket for more 

information on thresholds developed 

using this methodology. 

This method of assigning thresholds 

assumes that the total quantity of the 

substance becomes airborne. It does not 

consider the chemical properties that 

might affect the likelihood of an 

accidental release. The volatility of the 

listed chemicals is not taken into 

account; e.g., a gas could be assigned the 

same threshold as a liquid with 

relatively low volatility if the toxicity of 

the substances were similar. Thus, 

thresholds assigned by this method rank 

the chemicals primarily by toxicity. 

Because it seems probable that, under 

most circumstances, a gas would be 

more likely to be released to the air than 

a liquid with a low vapor pressure, it 

seems reasonable that gases should have 

lower thresholds than liquids with the 

same toxicity. In addition, the 

assumptions (e.g., wind speed, 

atmospheric conditions, duration of 

release) used in the dispersion models 

have a major effect on the results; many 

different quantities could be calculated 

for the same chemical, depending on the 

modeling assumptions made. The 

conditions affecting an actual release 

could vary greatly; therefore, the results 

of chemical-specific calculations such 

as those used under this method may 

have little relation to what might 

happen during an actual release. 

TPQ Method (Toxics). EPA also 

considered using the TPQs under 

EPCRA (SARA Title III) section 302 as 

the thresholds for toxic substances 

under this rulemaking. However, the 

purpose of the TPQs is to trigger 

reporting by the facility to state and 

local emergency planners of Uie 

presence of an EHS. The community 

planners then carry out an analysis of 

the hazards posed by the substance and 

use this analysis to set priorities forcommunity planning. The primary 

purpose of the threshold quantities 

under this rule, however, is to trigger 

mandatory prevention requirements to 

prevent the catastrophic accidental 

release of a regulated substance. 

Therefore, thresholds under this rule 

should represent quantities that are 

sufficiently hazardous (i.e., pose a risk 

of catastrophic event) to merit the 

requirement for a risk management plan 

on a site-specific basis. These quantities 

should be higher than the TPQs, which 

only represent a level where the hazard 

should be considered for planning 

purposes. EHSs on the proposed list 

with TPQs of 1,10, or 100 pounds 

generally have threshold quantities of 

500 pounds in today's proposed rule, 

based on the revised methodology; those 

with TPQs of 500 pounds generally have 

1,000-pound thresholds; and those with 

TPQs of 1,000 pounds generally have 

threshold quantities of 5,000 pounds. A 

TPQ of 10,000 pounds generally 

corresponds to a threshold of 10,000 

pounds. 

Alternative Overpressure Levels 

(Explosives). EPA considered basing the 

threshold quantity for explosives on 

other overpressure levels; for example, 

an overpressure of 2.0 psi, a level which 

could cause the partial collapse of walls 

and roofs of houses, would give a 

threshold quantity of 2,000 pounds. 

However, EPA believes threshold 

quantities calculated using the 

overpressure level of 3.0 psi are 

consistent with quantities that might 

have a catastrophic effect in case of an 

accidental release. 

Adopting OSHA's Thresholds 

For chemicals listed under both 

OSHA's chemical process safety 

standard and the list of regulated 

substances under CAA section 112(r), 

EPA considered adopting,thresholds 

established by OSHA. Because the 

OSHA standard is designed to protect 

employees from hazards associated with 

accidental releases of OSHA-listed 

chemicals in the workplace, EPA 

assumed that the OSHA thresholds 

represent accepted quantities that, if 

accidentally released, would be 

reasonably anticipated to cause death, 

injury, or serious adverse health effects 

in the workplace. EPA's proposed 

thresholds are intended to be protective 
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5114 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

ofthe public outside the workplace or 

off site. 

EPA reviewed the thresholds under 

OSHA's standard for chemicals on both 

lists and determined that EPA's 

thresholds generally are greater than or 

equal to OSHA's thresholds. EPA also 

noted that there are 15 substances for 

which EPA's thresholds are lower than 

OSHA's. These substances (CAS 

numbers in parentheses) and their 

OSHA thresholds are: Ammonia 

(anhydrous) (7664-41-7), 10,000 

pounds; ammonia (aqueous solution, 

concentration greater than 44 percent) 

(7664-41-7), 15,000 pounds; boron 

trichloride (10294-34-5), 2,500 pounds; 

bromine (7726-95-6), 1,500 pounds; 

chlorine (7782-50-5), 1,500 pounds; 

chlorine dioxide (10049-04-4), 1,000 

pounds; fluorine (7782-41-4), 1,000 

pounds; formaldehyde (50-00-0), 1,000 

pounds; hydrogen chloride (anhydrous) 

(7647-01-0), 5,000 pounds; hydrogen 

cyanide (anhydrous) (74-90-8), 1,000 

pounds; hydrogen fluoride (7664-39-3), 

1,000 pounds; hydrogen peroxide 

(concentration 52 percent or greater) 

(7722-84-1), 7,500 pounds; hydrogen 

sulfide (7783-06-4), 1,500 pounds; 

methyl chloride (74-87-3), 15,000 

pounds; and methyl mercaptan (74-93-

1), 5,000 pounds. 

The thresholds proposed today for the 

list of regulated substances under CAA 

section 112(r) generally are not equal to 

those for the highly hazardous 

substances listed under the OSHA 

standard. Thresholds that are protective 

of the worker may differ from levels Uiat 

are protective of the public. EPA 

believes it is reasonable for the EPA 

thresholds generally to be equal to or 

greater than the OSHA thresholds 

because workers generally are located 

closer to the chemicals than the public. 

EPA recognizes that OSHA's thresholds 

for the 15 substances discussed above 

were established by rulemaking, which 

may indicate a consensus on the amount 

that can be reasonably anticipated to 

cause serious adverse effects not only 

within the workplace but also on the 

public. This consensus may support 

raising EPA's thresholds for these 15 

substances to OSHA's levels. However, 

EPA has proposed thresholds lower 

than OSHA's for these 15 substances 

because EPA believes Uiat Uie scientific 

methodology applied to determine Uie 

protective thresholds for these 15 

chemicals should be consistent with 

that used for the remaining substances 

on Uie EPA list. By adopting a 

consistent methodology, EPA can 

ensure that there is a reasonable 

relationship between the thresholds for 

substances on EPA's list that are on 

OSHA's list and those Uiat are not, and 

between substances listed in the initial 

rulemaking and those added 

subsequently by petition or other 

revision. The Agency requests 

comments on these issues and, given the 

extent to which this rule and the rule 

promulgated by OSHA overlap, the 

degree that accidental releases of toxics, 

flammables and explosives and their 

corresponding offsite effects will be 

reduced by the OSHA rule. 

EPA requests comments on the 

proposed methodologies for establishing 

threshold quantities for toxic, 

flammable, and explosive substances 

covered in this proposed rule. EPA also 

requests comments on options 

considered for setting thresholds. 

4. Determination of Presence of 

Threshold Quantity 

The purpose of the threshold 

determination is to evaluate (a) whether 

a facility is covered for a specific 

regulated substance and (b) whether a 

particular location within the facility is 

subject to regulations based on the 

presence of the substance. In deciding 

now the presence of a threshold 

quantity ofa listed substance at a 

facility should be determined, EPA 

considered several possibilities and 

reviewed the methods used by other 

agencies and programs. Under section 

302 of EPCRA (SARA Title III), a facility 

is covered if the total quantity of an EHS 

present on site at any one time is in 

excess of its TPQ. New Jersey's 

threshold also is applied to the 

maximum quantity on site at any time. 

Under Delaware's approach, facilities 

must iletermine the maximum quantity 

of a toxic chemical that could be 

released at one time, using guidance 

provided by the state to account for 

facility-specific factors. If this potential 

release quantity is greater than the 

threshold, the facility is covered by the 

Delaware RMP regulations. OSHA 

proposed that the threshold quantity be 

based on the amount used in a process, 

rather than the quantity on site, to 

determine whether a threshold quantity 

is present, where a process is defined as 

"any use, storage, manufacturing, 

handling, processing, or the on-site 

movement. . ., or combination of these 

activities." Vessels that are 

intercennected or vessels that are not 

intercennected but could be involved in 

a potential release are considered a 

single process. 

EPA is proposing to apply the 

threshold quantity to the maximum total 

quantity of a substance in a process, 

using the same definition used by 

OSHA. This definition would apply to 

the maximum quantity, at any one time, 

in a single vessel, or in several vessels 

that could be involved at one time in a 

potential release, or in a group of 

interconnected vessels. Interconnected 

vessels could include, for example, 

storage tanks, surge tanks, or weigh 

tanks that may be connected to another 

vessel or processing system by pipes, 

pumps, or other conveyance equipment 

used to transfer a substance from one 

vessel to another. The proposed 

approach to determining whether a 

facility or location is covered focuses on 

the quantity of a substance Uiat could be 

released in a single accident. For 

example, if a facility uses 300 pounds of 

chlorine in one process, uses 150 

pounds to treat wastewater, and stores 

600 pounds, the facility would have a 

total of 1,050 pounds quantity on site. 

The proposed threshold quantity for 

chlorine is 1,000 pounds. If all of Uie 

chlorine is kept and used in a single 

area, where a fire or explosion could 

affect the chlorine cylinders, more than 

1,000 pounds have the potential of 

being released in a single incident, 

thereby exceeding Uie threshold. If, 

however, the process area, storage area, 

and wastewater treatment facility are 

widely separated (and not otherwise 

interconnected by pipes, pumps, or 

other conveyance equipment), a single 

incident would be unlikely to lead to a 

large chlorine release. EPA also believes 

that considering only the quantity in 

one vessel or interconnected vessels 

would not be sufficiently protective in 

some cases. For example, debris from an 

explosion could puncture a nearby 

container, or a fire could cause a 

number of containers or pipes to 

rupture. Therefore, EPA is also 

proposing that threshold determination 

consider all vessels located sufficiently 

close to each other Uiat they might be 

involved in a release at one time. EPA 

believes this approach is relatively 

simple to implement and verify and also 

reasonably approximates the potential 

release quantity. The Agency 

recognizes, however, Uiat this method of 

threshold determination would not 

address some potentially hazardous 

situations. Different materials with the 

same characteristic (e.g., flammability), 

or different materials with various 

hazards, that are stored in close 

proximity to each other but are all 

stored in quantities below the threshold 

quantity, might pose a potential hazard 

to the community, but the threshold 

quantity would not be exceeded because 

each substance is considered 

individually. EPA believes it is not 

feasible to attempt to address all 

potential hazards of combinations of 

substances. EPA requests comments on 

the proposed approach. 
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Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5115 

EPA considered applying the 

threshold quantity to the total quantity 

on site at a facility, as under EPCRA 

(SARA Title III) section 302. A facility 

would be covered if it had present an 

amount of a listed substance exceeding 

its threshold quantity regardless of its 

location or distribution on the site. This 

method is clear and unambiguous; no 

complicated formulas or definitions 

need to be applied. The Agency 

believes, however, that it is unlikely 

that the contents of several vessels that 

are not interconnected and that are 

widely separated would be released 

simultaneously, causing a catastrophic 

event. Therefore, using the total 

quantity on site for threshold quantity 

determination appears to be an overly 

conservative approach. 

Another approach considered was to 

base determination of the threshold on 

the maximum quantity of Uie regulated 

substance capable of being released in a 

worst-case accidental release. This 

approach is used by Delaware for toxic 

chemicals. Under the Delaware 

regulation, Uie facilities must calculate 

a worst-case potential release quantity 

based on formulas provided. Some 

difficulties have been reported with this 

approach; for example, the calculations 

require a technical knowledge not 

available at the full range of potentially 

covered facilities. Again, EPA believes 

this approach may present enforcement 

and compliance problems due to the 

lack of easily verifiable criteria. EPA 

requests comments on Uie proposed 

definition for threshold quantities and 

the alternative approaches considered as 

options. 

5. Threshold Exemptions 

EPA is proposing several exemptions 

to limit the quantities of substances 

included in the threshold 

determination. EPA would adopt the 

exemption applied under EPCRA 

(SARA Title III) which does not 

consider substances in mixtures if they 

represent less than one percent of the 

mixture by weight. Regulated 

substances in such dilute solutions are 

unlikely to pose a hazard to the 

community in Uie event of an accidental 

release. In addition, it might not be 

feasible in many cases for facilities to 

calculate small quantities of substances 

that may be contained in mixtures. 

EPA also is proposing to exempt 

substances contained in "articles" from 

Uie threshold determination. The OSHA 

definition of an article would be used 

(29 CFR 1910.1200(b)). Batteries (after 

their manufacture) would be considered 

articles under this definition. In 

addition, EPA is proposing to exempt 

substances used for the following 

purposes from inclusion in the 

threshold determination: substances 

that are a structural component of the 

facility; substances used for routine 

janitorial maintenance; substances ih 

consumer products; and substances in 

water drawn from the environment or 

municipal sources. EPA also would 

exempt activities in laboratories when 

under Uie supervision of a technically 

qualified person. EPA considers it less 

likely Uiat substances stored in these 

exempt forms could be involved in 

accidental releases of a catastrophic 

nature. 

These proposed exemptions parallel 

the exemptions provided under EPCRA 

(SARA Title III) sections 311 and 312 for 

threshold calculations. EPA recognizes 

that under EPCRA (SARA Title ffl) 

section 302, there are no similar 

exemptions from threshold 

determination. However, as noted 

previously, EPCRA (SARA Title III) 

section 302 does not require facilityspecific prevention measures, in 

contrast to the requirements of CAA 

section 112(r). EPA believes these 

exemptions are necessary to avoid 

covering facilities whose use ofthe 

substances does not merit the 

substantial regulations required under 

the CAA and facilities who do not 

directly use the substance because it is 

contained in an article, in process water, 

in other products, or in specific 

supervised situations. For example, 

without the article exemption, car 

dealers and service stations could be 

covered because of the acid in car 

batteries. Under EPCRA (SARA Title IH) 

section 302, facility notification to local 

and state emergency planners may be 

appropriate in order for them to 

consider Uie risk to the community, but 

mandatory prevention requirements in 

all cases would be excessive. 

In addition, EPA is proposing tb 

exempt listed flammable substances 

used solely for facility consumption as 

fuel. This exemption is consistent with 

OSHA's approach in its proposed rule 

for process safety management. 

6. Considerations for Mixtures 

EPA notes that certain listed 

substances are covered only if they are 

in concentrations by weight above 

specified levels; for example, 

hydrochloric acid would be covered 

only when it is in solution at a 

concentration of 25 percent or greater, 

aqueous solutions of ammonia must be 

considered only if the concentration is 

20 percent or greater, and hydrogen 

peroxide solutions must be considered 

if the concentration is greater than 52 

percent. Stationary sources would not 

be required to estimate quantities of 

more dilute solutions of these 

substances. These concentrations 

represent typical industry handling of 

these mixtures. For mixtures or 

solutions of other listed substances, 

determination of whether a threshold 

quantity is present would be based on 

the quantity of Uie listed substance in 

Uie mixture or solution. For example, 

for a 25 percent solution of a listed 

substance with a threshold quantity of 

500 pounds, more than 2,000 pounds of 

the solution would be needed to exceed 

Uie threshold for the listed substance. 

IV. Other Issues 

A. State Programs 

The Act encourages states to develop 

programs to implement CAA statute 

requirements. EPA will be publishing 

guidance to assist in the development of 

state programs and in the 

implementation of section 112(r) 

requirements. Section 112(1)(1) indicates 

that states may submit State Program 

Plans outlining the implementation and 

enforcement of section 112(r)' 

requirements. The chemical list and 

reporting thresholds EPA adopts will 

provide a minimum set of requirements 

for state programs to adopt. States, 

however, are not restricted from having 

a more stringent program than the one 

EPA is proposing. 

Several states have developed their 

own chemical accident prevention 

regulations. As previously noted, 

California, Delaware, and New Jersey 

already have chemical accident 

prevention regulations Uiat require 

facilities to develop and implement risk 

management plans. For each of these 

programs, the applicability ofthe 

regulations is determined by a list of 

chemicals with reporting thresholds. 

The California program uses the list and 

thresholds established under EPCRA 

(SARA Title III) section 302; Uiat is, Uie 

Califomia program covers all 360 

extremely hazardous substances on the 

EPCRA (SARA Title ID) section 302 list 

at their TPQs. New Jersey has developed 

its own list of chemicals and thresholds. 

Delaware has also developed a separate 

list; Delaware's thresholds are 

dependent on both Uie quantity of Uie 

substance qn site and the distance to the 

nearest population. If an established 

state program does not include all the 

substances at the threshold quantity set 

by EPA (or at a lower, more stringent 

threshold), the program would have to 

be revised to bring it into compliance 

with Uie Federal requirements when 

they are promulgated. 
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B. OSHA's List of Highly Hazardous 

Chemicals 

In developing the proposed list of 

substances and thresholds, EPA 

considered the possibility of adopting 

the list of highly hazardous chemicals 

and thresholds OSHA lists for its 

chemical process safety standard. EPA 

conducted its analysis based on the 

proposed OSHA standard available at 

the time, with coordination with OSHA 

between their proposal and final 

versions. However, OSHA's list does not 

include all the substances mandated for 

listing by Congress. It does not include 

all EHSs that meet EPA's proposed 

criteria and includes several substances 

that EPA cannot list under the Act. It 

also includes a number of substances 

that are not in commercial production. 

EPA is required to consider likelihood 

of a release; substances that are not in 

commercial production would be 

unlikely to be released in significant 

quantities. Therefore, the OSHA list 

does not meet EPA's Congressional 

mandate. Approximately 20 percent of 

OSHA's list is made up of reactive 

chemicals. EPA is currently considering 

whether reactive chemicals pose a 

potential threat to the public health or 

welfare (as opposed to worker safety), 

and is deferring listing such substances 

for the accidental release provisions 

pending further analysis of their 

hazards. For these reasons, EPA 

determined the OSHA list could not be 

adopted in its entirety. EPA and OSHA 

continue to work together to coordinate 

their lists to Uie extent possible. 

EPA has proposed the same method 

as OSHA for determining whether the 

quantity ofa substance at a facility 

exceeds the threshold. However, EPA 

and OSHA used different methods to 

assign threshold quantities. EPA's 

proposed list includes 61 chemicals that 

also are listed by OSHA (50 on EPA's 

list of toxic substances and 11 on Uie list 

of flammable substances). Of Uie 

substances Uiat are listed by both OSHA 

and EPA, 10 (9 toxics and 1 flammable) 

have identical thresholds. EPA's 

thresholds are higher than OSHA's for 

36 substances (26 toxics and 10 

flammables); because OSHA's 

thresholds relate to worker protection, 

while EPA's are intended to protect the 

community, it is reasonable Uiat EPA's 

thresholds should be higher. However, 

OSHA's thresholds are higher for 15 

substances. 

C Relationship to EPCRA (SARA Title 

III) Section 302/303 

Under EPCRA (SARA Title HI) section 

302, EPA published a list of extremely 

hazardous substances (EHSs) and 

threshold planning quantities (TPQs). 

Facilities with EHSs, in quantities 

exceeding Uie TPQ must notify Uie State 

Emergency Response Commission and 

Local Emergency Planning Committees. 

Identification of facilities with EHSs 

above their TPQs is intended to provide 

local emergency planners with a basis 

for farther analysis of the potential 

danger posed by these facilities. The 

TPQs do not trigger any specific 

requirements, other than notification 

and designation of a facility coordinator, 

for facilities with EHSs, nor do they 

trigger any specific emergency planning 

requirements at the facility other than 

cooperation with the state and local 

planners in the planning process. 

However, some facilities already may be 

instituting prevention programs, based 

especially on the heightened awareness 

of hazards that has resulted from EPCRA 

(SARA Title III) section 303 activities. 

The main distinction between EPCRA 

(SARA Title III) section 303 

requirements and Uie CAA requirements 

is that EPCRA (SARA Title III) section 

303 focuses on community planning, 

while the CAA focuses on planning at 

the facility for accident prevention and 

response. The list of substances and 

threshold quantities being proposed 

under CAA section 112(r) triggers 

mandatory prevention requirements by 

facilities for prevention of accidental 

releases. EPA, therefore, believes it is 

appropriate that Uie list of toxic 

chemicals under CAA section 112(r) 

should be limited to gases and volatile 

liquids with evidence of production, 

unlike the EHS list, which is based only 

on toxicity, and that Uie thresholds for 

toxic chemicals under CAA section 

112(r) should be higher than the TPQs 

under EPCRA (SARA Title III) section 

302. In addition, determination of the 

presence of a TPQ of an EHS under 

EPCRA (SARA Title ffl) section 302 is 

based on Uie total quantity of Uie EHS 

at Uie facility, while under CAA section 

112(r), the proposed method of 

threshold determination is based on the 

quantity ofthe regulated substance in a 

process. EPA believes it is appropriate 

under EPCRA (SARA Title III) section 

302 to identify facilities based on Uie 

total quantity on site; emergency 

planners can then take factors such as 

location and distribution of vessels into 

account when setting priorities for 

planning. On the other hand, EPA 

believes it is more appropriate under 

CAA section 112(r), because of Uie 

associated requirements, to consider the 

quantity that has the potential to be 

released in a single accident and cause 

serious effects beyond the fenceline. 

EPA may decide to list flammable and 

explosive substances under EPCRA 

(SARA Title III) section 302, following 

completion of its analysis of the hazards 

of such chemicals. Because of the 

different purposes of EPCRA (SARA 

Title III) section 302 and CAA section 

112(r), it may be appropriate to have 

somewhat different lists and thresholds 

under EPCRA (SARA Title III) section 

302. For example, to provide local 

emergency planners with sufficient 

information to allow them to set 

planning priorities for their 

communities, EPA may use less 

stringent criteria for listing (e.g., blasting 

agents as well as high explosives may be 

listed) and set lower thresholds (e.g., 

thresholds for explosives may be set 

using a lower overpressure level, such 

as 1.0 psi or 2.0 psi) under EPCRA 

(SARA Title III) section 302. 

D. Agricultural Nutrient Exemption 

Under CAA section 112(r), EPA is 

authorized to establish higher threshold 

quantities for, or exempt entirely, 

chemicals used as agricultural nutrients 

when held by farmers. EPA believes that 

ammonia is the only chemical on Uie 

proposed list of substances that would 

be used as an agricultural nutrient and 

thus could be subject to Uie higher 

threshold or exemption. EPA is 

proposing to exempt ammonia from the 

requirements of this rule when held by 

a farmer as an agricultural nutrient. EPA 

is proposing this exclusion for two 

reasons. First, the farms Uiat use 

ammonia as a fertilizer are primarily 

growing corn, wheat, and cotton, and 

involve large acreages and the ammonia 

is intentionally released to the 

environment. Second, many elements of 

chemical accident prevention programs 

may not be directly relevant to Uie use 

of ammonia as a fertilizer. EPA requests 

comments on the proposed exemption. 

EPA notes that farm contractors who 

sell ammonia as a fertilizer would be 

covered by today's proposed rule. 

E. Information Gathering Efforts 

Before EPA began writing its 

proposed rules for accidental release 

prevention, Uie Agency decided to seek 

information from those already 

implementing similar regulations. EPA 

staff met extensively with officials in 

three states and held interviews with 

seven facilities Uiat have developed 

RMPs under state laws. To gather more 

information, EPA held eight focus 

groups, five with facilities (two each in 

New Jersey and California, one in 

Delaware), and three with administering 

agency officials in California, to elicit 

their opinions on the regulations and 

their ideas about the most useful 
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Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5117 

program components. After analyzing 

the results of these meetings, EPA held 

a two-day seminar on issues Uiat have 

arisen at Uie state level. Officials from ., 

California, Delaware, and New Jersey, as 

well as Minnesota, Texas, New York, 

and Wisconsin, attended the meetings. 

On Uie second day, otiier groups that 

had expressed an interest, including 

trade associations, labor unions, 

environmentalists, and organizations of 

public officials, joined the discussion. 

Participants were concerned that to 

the extent possible, Uie OSHA, EPA, and 

state chemical lists and related 

regulations should be consistent. 

Several facilities indicated that they 

would like Uie regulations arranged so 

that if they are in compliance with one 

rule, they would be in compliance with 

all rules, at least for a specific chemical. 

It was noted that the chemical list 

should be based on criteria; thresholds 

should be developed on a risk-based 

system. In general, the focus group 

participants found the thresholds used 

in their states reasonable, regardless of 

the actual threshold quantities, which 

varied from state to state. A report on 

this information gathering effort entitled 

Clean Air Act of 1990, Chemical 

Accident Release Provisions, Report on 

Focus Groups and Round Table 

Discussions, transcripts of the focus 

group sessions, and a report on the twoday seminar are available in the docket. 

V. Petitions for Additions and Deletions 

A. Information Required from Petitioner 

The Act requires EPA to review the 

list at least every five years; EPA may 

revise the list either through petitions or 

by Agency initiative. EPA is required to 

develop procedures for the addition and 

deletion of substances from the list; 

these procedures are to be consistent 

with those applicable to the list in CAA 

section 112(b). 

EPA will consider and respond to 

petitions to modify the list of regulated 

substances for accidental release 

prevention within 18 months of 

submission of the petition. For EPA to 

complete its review of petitions and 

publish the results of its determinations 

in a timely and efficient manner, the 

data presented in the petition must be 

complete and technically sound. EPA's 

review would be facilitated if the 

petitioner presents Uie information in 

the order listed below. 

o Name and address of the petitioner 

and a brief description of the 

organization(s) that the petitioner 

represents, if applicable. 

o Name, address, and telephone 

number ofa contact person for the 

petition. 

o Common chemical name(s), 

common synonym(s). Chemical 

Abstracts Service (CAS) number, and 

chemical formula and structure. The 

CAS number is a unique number 

assigned to chemical substances by the 

American Chemical Society Chemical 

Abstracts Service Registry System. The 

CAS numbers are independent of 

nomenclature and have no chemical 

significance. They are assigned as each 

new chemical enters the CAS Registry 

System. 

° Action requested. The petitioner 

must identify whether Uie request is to 

add to or delete from the list of 

regulated substances for accidental 

release prevention. c 

» Rationale supporting the 

petitioner's position. Each petition must 

present a discussion of the rationale to 

add or delete each substance based 

upon the data presented and their 

relationship to the criteria for addition 

or deletion. A short summary of the 

rationale must be submitted along with 

a more detailed narrative that includes 

a discussion of the available data on the 

potential for acute adverse human 

health effects that occur as a result of 

exposure to the substance. Physical and 

chemical data related to the likelihood 

of accidental releases and the magnitude 

of human exposure also should be 

discussed. For a petition to add, data 

must be submitted showing that the 

criteria for listing are met. Chemicals 

meet the criteria for listing if they meet 

the mammalian toxicity criteria for 

listing as EHSs (discussed in Section III 

C ofthis preamble), are gases or liquids 

with vapor pressure of 0.5 mm Hg or 

higher under ambient conditions, and 

are in production in commercial 

quantities. Less volatile chemicals that 

meet the toxicity criteria will be 

considered for listing if they have a 

history of involvement in accidents that 

caused death or injury. For flammable 

chemicals, data should indicate that the 

substances are flammable gases under 

ambient conditions, or that they are 

liquids with boiling point below 100 °F 

(37.8 °C) and flash point below 73 °F 

(22.8 °C). For a petition to delete, data 

must be submitted demonstrating that 

the substance would not reasonably be 

expected to cause death, injury, or 

serious adverse effects to human health 

or the environment in the event of an 

accidental release. Available data on all 

hazards presented by the chemical 

should be included. 

o Supporting data. The petitioner 

must provide EPA with sufficient 

information to support scientifically his 

or her request to add to or delete from 

the list of regulated substances for 

accidental release prevention. Duplicate 

copies of all material submitted and an 

English translation of any information 

published in a foreign language should 

be included with Uie petition in order 

to expedite Uie review process. 

All data presented must meet basic 

criteria for acceptable scientific quality. 

These include, but are not limited to, 

appropriate study design, quality ofthe 

scientific approach/method, appropriate 

quality assurance and quality control 

procedures, and appropriate statistical 

analyses. 

The supporting data for the petition 

must contain, at a minimum, the 

following elements: 

° List of supporting documents. The 

petitioner must include a summary list 

of all supporting documents included 

with the petition. 

° Literature searches. The petitioner 

must include a printed copy of all 

literature searches conducted to identify 

data available for the substances, 

including identification of the 

databasefs) searched, the search 

strategy, dates covered, and printed 

results. The literature searches must 

have been conducted within six months 

prior to submission of the petition. 

o Effects data. Each petition must 

include summary tables identifying all 

studies cited. The petitioner must 

submit printed copies of the studies 

cited on these tables. The reports of 

effects data should include all available 

reports on effects of short-term exposure 

to the chemical and should not be 

limited to reports on the effect for which 

the chemical was listed. Human studies, 

animal studies, other environmental 

effects studies, and supplementary data 

such as results from short-term in vitro 

tests, toxicokinetic studies, comparative 

metabolism studies, structure-activity 

relationships, and other relevant 

toxicological studies may be submitted. 

Studies will be evaluated for 

adequacy using standard EPA guidance 

documents and basic toxicologic 

principles. EPA will place greater 

confidence in studies that have been 

published in peer-reviewed scientific 

journals or books. In addition, Uie 

petitioner may be aware of supporting 

studies, data, or reports Uiat were not 

published in peer-reviewed journals or 

books. In such cases, the petitioner 

should submit a printed copy of each 

relevant non-peer-reviewed citation. 

Examples of such citations may include 

proceedings of scientific meetings, 

studies conducted at an industrial site 

for internal purposes, and some 

government-sponsored reports/ 

assessments. 

o Exposure and accident history data. 

The petition should include data related 

to the potential for serious adverse 
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5118 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

human health or environmental effects. 

Relevant physical and chemical 

properties ofthe substance (e.g., boiling 

point and vapor pressure) should be 

included, with literature citations. Air 

dispersion modeling results may be 

included. Assumptions and data used 

for Uie modeling should be presented 

clearly, and documentation for the 

model used should be included in the 

submission. Historical data on accidents 

involving the substance may be 

included, clearly citing Uie sources of 

the data. 

B. Petition Process 

The guidance presented in this 

proposed rulemaking is intended to 

provide a general framework for 

determining petition adequacy. Because 

most petitions will have specific issues 

not covered by this guidance, 

individuals wishing to petition EPA to 

modify the list of regulated substances 

for accidental release prevention are 

encouraged to request a pre-petition 

conference with EPA. Such a meeting 

would facilitate submittal of complete 

and technically sound petitions. To 

arrange a pre-petition conference, please 

contact CAA 112(r) Petition 

Coordinator, Chemical Emergency 

Preparedness and Prevention Office 

(OS-120), 401 M Street SW., 

Washington DC 20460. At the time a 

pre-petition conference is requested, the 

potential petitioner must be prepared to 

submit a proposed agenda for the 

meeting and a list of participants. 

A petition to modify the hst of 

regulated substances for accidental 

release prevention under section 112(r) 

of the Clean Air Act should be sent to 

the following address to expedite its 

review. Environmental Protection 

Agency, Chemical Emergency 

Preparedness and Prevention Office, 

OS-120, 401 M Street, SW., 

Washington, DC 20460. 

Upon receipt of a petition, EPA will 

first review the petition for 

completeness. If the petition is found to 

be incomplete, EPA will return it to the 

petitioner identifying the omissions. 

The petitioner may correct Uie 

deficiencies and resubmit the petition. 

This action will be considered 

equivalent to submitting a new petition; 

thus, EPA will have 18 months to 

review the petition contents and publish 

a decision to grant or deny the petition. 

If the petition is found to be complete, 

EPA proposes to publish the following 

two notices in the Federal Register: 

1. Notice of Petition Receipt and 

Request for Comments: This notice will 

announce that a complete petition has 

been received and will identify the 

following: the petitioner, the action 

requested (regulated substance, 

addition/deletion), Uie rationale and 

summary of the key data submitted in 

support ofthe petition, and the list of 

studies submitted by the petitioner to 

support the request. In response to this 

notice, EPA will request that interested 

parties submit additional, pertinent 

scientific information Uiat was not 

identified by the petitioner if such 

information might assist EPA in making 

the decision to grant or deny the 

petition. Additional data will be 

accepted for sixty days following 

putelication of this notice. The request 

for information will constitute a request 

for public comments on the petition. All 

pertinent information and comments 

received will be addressed in the notice 

granting or denying the petition. 

2. Publication of Decision: This notice 

will announce EPA's decision to grant 

or deny a specific petition. 

EPA anticipates publishing the two 

notices discussed above within 18 

months of receiving a complete petition. 

EPA will not accept additional petitions 

on the same substance following 

publication of a final notice of the 

decision to grant or deny a petition 

unless new data become available that 

could significantly affect the basis for 

the decision made by EPA. If significant 

additional data are available, interested 

persons may submit these data through 

the petition procedures identified in 

this notice. Reference should be made to 

previous petitions for a specific 

substance, identifying the date Uie 

petition was submitted and the previous 

petitioner. Information previously 

submitted need not be resubmitted but 

may be cited by reference for 

reconsideration. EPA requests 

comments on the proposed information 

to be required from the petitioner and 

the proposed petition process. 

VI. Discussion ofthe Proposed Rule 

EPA is proposing to add Part 67 to 

Title 40 of the Code of Federal 

Regulations, which would include the 

list of regulated substances and 

threshold quantities, as well as the 

requirements for the petition process to 

add regulated substances to the list or to 

delete regulated substances from the 

list. 

Proposed § 68.5 would establish the 

procedures to determine whether a 

threshold quantity of a regulated 

substance is present at a stationary 

source. Specific exemptions to the 

threshold determination procedure are 

also included for mixture 

concentrations, articles, and certain uses 

and activities. 

Proposed §68.100 would establish the 

purpose of the subpart as the 

designation of regulated substances and 

their threshold quantities, and 

establishment of the requirements for 

petitions to add substances or delete 

substances from Uie list. 

Proposed § 68.120 would specify the 

requirements for petitions to the Agency 

to add substances to the list, and to 

delete substances from the list. 

Proposed § 68.125 would exempt 

ammonia used as an agricultural 

nutrient when held by a farmer. 

Proposed § 68.130 would establish Uie 

list of regulated substances, including a 

list of toxic substances, a list of 

flammable substances, and a list 

criterion for commercial high 

explosives. This section also would 

establish Uie threshold quantities for all 

listed substances. 

VII. Required Analyses 

A. E.O. 12291 

Under Executive Order 12291, the 

Agency must judge whether a regulation 

is "major" and thus subject to the 

requirement for a Regulatory Impact 

Analysis (RIA). Under E.O. 12291, a 

major rule is one that is likely to result 

in: 

1. An adverse (cost) impact in the 

economy of $100 million, 

2. A major increase in cost or prices 

to consumers, individual industries, 

Federal, state, or local government, or 

geographic region, or 

3. Significant adverse effects on 

competition, employment, investment, 

productivity, innovation, or the ability 

of U.S.-based enterprises in domestic or 

export markets. 

Based on Uie RIA, EPA estimates that 

approximately 140,500 facilities will be 

covered by the three proposed hazards 

lists and thresholds (i.e., toxic, 

flammables, and explosives). These 

facilities include 22,440 manufacturers 

(18,960 of whom are covered by the 

OSHA rule); 33,250 public drinking 

water and waste treatment systems 

(15,400 covered by OSHA); 50,000 cold 

storage facilities (42,500 covered by 

OSHA); 4,460 wholesalers (2,240 

covered by OSHA); 1,240 service 

industry facilities (776 covered by 

OSHA); 2,980 private utilities (3,000 

covered by OSHA); and 20,000 propane 

retailers. The average number of 

regulated substances varies from one per 

facility for cold storage facilities, to 13 

per facility for highly complex 

manufacturing facilities. 

EPA has determined the proposed 

rule is not a major rule for the purposes 

of E.O. 12291 because the list, by itself, 

imposes no cost on facilities. The cost 

impact of the list and thresholds derives 

from compliance with the risk 
P.20 

Federal Register / Vol. 58, No. 11 /Tuesday, January 19, 1993 / Proposed Rules 5119 

management regulations and other 

reasonable regulations, which are 

triggered by the presence of a regulated 

substance above its threshold quantity. 

Because Uie impact of Uie list and 

threshold decisions are felt through the 

risk management regulations, EPA has 

prepared a combined preliminary RIA 

entitled, "Regulatory Impact Analysis in 

Support of Listing Regulated Substances 

and Thresholds and Mandating Risk 

Management Programs for Chemical 

Accident Prevention, as Required by 

section 112(r) of Uie CAA," which 

analyzes Uie impacts of various list and 

threshold options on the risk 

management requirements. The RIA is 

available in the docket. 

The petition process is the only aspect 

of this rulemaking that is directly 

attributed to the listing of substances. 

EPA estimates that the petition process 

under this rulemaking will cost a 

facility submitting a petition an average 

of $5,000. EPA estimates that there will 

be 11 petitions a year. EPA anticipates 

that the cost to the Federal govemment 

for processing and reviewing the 

petitions will be approximately equal to 

Uie cost to facilities for filing a petition. 

The total annual cost is estimated to be 

$110,000 ($5,000 x 2 x 11 petitions). 

B. Regulatory Flexibility Act 

In accordance with the Regulatory 

Flexibility Act of 1980, Federal agencies 

must evaluate the effects of the rule on 

small entities and examine alternatives 

Uiat may reduce these effects. Because 

Uie proposed rule, by itself, has no cost 

impact on facilities, a separate 

Regulatory Flexibility analysis was not 

conducted, but is included in the 

combined RIA, available in the docket. 

C Paperwork Reduction Act 

The information collection 

requirements in this proposed rule have 

been submitted for approval to Uie 

Office of Management and Budget 

(OMB) under Uie Paperwork Reduction 

Act, 44 U.S.C. 3501 et seq. An 

Information Collection Request 

document has been prepared by EPA 

(ICR No. 1601.1) and a copy may be 

obtained from Sandy Farmer, 

Information Policy Branch, EPA, 401 M 

St. SW. (PM-22Y), Washington, DC 

20460, or by calling (202) 260-2740. 

Public reporting burden for this 

collection of information in the petition 

process, Uie only aspect of Uie proposed 

rule involving reporting or 

recordkeeping, is estimated to be 

approximately 138 hours, including 

time for reviewing instructions, 

searching existing data sources, 

gathering and maintaining data needed, 

and completing and reviewing the 

collection of information. EPA estimates 

that there will be 11 petitions a year. 

The total annual burden is estimated to 

be 1,518 hours (138 hours x 11 

petitions). 

Send comments regarding the burden 

estimate or any other aspect of this 

collection of information to Chief, 

Information Policy Branch, PM-223Y, 

U.S. EPA, 401M St. SW., Washington, 

DC 20460, and the Office ofinformation 

and Regulatory Affairs, Office of 

Management and Budget, Washington, 

DC 20503, Attn: Desk Officer for EPA. 

The final rule will respond to any OMB 

or public comments on the information 

collection requirements contained in 

this proposal. 

List of Subjects in 40 CFR Part 68 

Chemicals, Hazardous substances, 

Extremely hazardous substances, 

Intergovernmental relations, Clean Air 

Act, Chemical accident prevention. 

Dated: December 30,1992. 

William K. Reilly, 

Administrator. 

For the reasons set out in the 

preamble, title 40, chapter I, subchapter 

C of the Code of Federal Regulations is 

proposed to be amended by adding a 

new part 68 to read as follows: 

PART 68—CHEMICAL ACCIDENT 

PREVENTION PROVISIONS 

Subpart A—General 

Sec. 

68.1 Scope. 

68.3 Definitions. 

68.5 Threshold determination. 

Subpart B—Rish Management Plan 

Requirements [Reserved] 

Subpart C—Regulated Substances for 

Accidental Release Prevention 

68.100 Purpose. 

68.120 Petition process. 

68.125 Exemptions. 

68.130 List of substances. 

Authority: 42 U.S.C. 7412(r). 

Subpart A—General 

§68.1 Scops. 

This part sets forth requirements for 

chemical accident prevention steps that 

must be taken by the owner or operator 

of stationary sources. 

§68.3 Definitions. 

For Uie purposes ofthis part: 

Accidental release means an 

unanticipated emission of a regulated 

substance or other extremely hazardous 

substance into Uie ambient air from a 

stationary source. 

Administrator means the 

administrator of the U.S. Environmental 

Protection Agency. 

Article means a manufactured item 

that is formed to a specific shape or 

design during manufacture, Uiat has end 

use functions dependent in whole or in 

part upon the shape or design during 

end use, and Uiat does not release or 

otherwise result in exposure to a 

regulated substance under normal 

conditions of processing and use. 

CAS means the Chemical Abstracts 

Service. 

Process means any activity involving 

a regulated substance including any use, 

storage, manufacturing, handling, or 

onsite movement of such substances, or 

combination of these activities. For the 

purposes of this definition, any group of 

vessels that are interconnected, or 

separate vessels that are located such 

that a regulated substance could be 

involved in a potential release, shall be 

considered a single process. 

Regulated substance is any substance 

listed under section 112(r)(3) ofthe 

Clean Air Act as amended, and § 68.130. 

Stationary source means any 

buildings, structures, equipment, 

installations, or substance emitting 

stationary activities which belong to the 

same industrial group, which are 

located on one or more contiguous 

properties, which are under the control 

of the same person (or persons under 

common control), and from which an 

accidental release may occur. A 

stationary source includes 

transportation containers that are no 

longer under active shipping orders and 

transportation containers that are 

connected to equipment at the 

stationary source for the purposes of 

temporary storage, loading, or 

unloading. 

Threshold quantity means the 

quantity specified for regulated 

substances under section 112(r)(5) ofthe 

Clean Air Act as amended, and listed in 

§ 68.130 and determined to be present at 

a stationary source as specified in 

§68.5. 

Vessel means any reactor, tank, drum, 

barrel, cylinder, vat, kettle, boiler, pipe, 

hose, or other container. 

§68.5 Threshold dotormination. 

(a) A threshold quantity of a regulated 

substance as listed in § 68.130 is present 

at a stationary source if the total 

quantity of Uie regulated substance 

contained in a process exceeds the 

threshold. 

(b) For the purposes of determining 

whether more than a threshold quantity 

of a regulated substance is present at the 

stationary source, Uie following 

exemptions apply: 

(1) Concentrations ofa regulated 

substance in a mixture. If a regulated 

substance is present in a mixture and 
T " ^" 

P.21 

5120 Federal Register / Vol. 58^ No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

Uie concentration ofthe substance is 

below one percent by weight ofthe 

mixture, the amount of Uie substance in 

Uie mixture need not be considered 

when determining whether more than a 

threshold quantity is present at the 

stationary source. 

(2) Articles. Regulated substances 

contained in articles need not be 

considered when determining whether 

more than a threshold quantity is 

present at the stationary source. 

(3) Uses. Regulated substances used 

for the following purposes need not be 

included when determining whether 

more than a threshold quantity is 

present at the stationary source: 

(i) Use as a structural component of 

the stationary source; 

(ii) Use of products for routine 

janitorial maintenance; 

(iii) Use by employees of foods, drags, 

cosmetics, or other personal items 

containing the regulated substance; 

(iv) Use of regulated substances 

present in process water or non-contact 

cooling water as drawn from the 

environment or municipal sources, or 

use of regulated substances present in 

air used either as compressed air or as 

part of combustion; and 

(v) Use solely for consumption as fuel. 

(4) Activities in Laboratories. If a 

regulated substance is manufactured, 

processed, or used in a laboratory at a 

stationary source under the supervision 

of a technically qualified individual as 

defined in § 720.3(ee) of this chapter, 

the quantity of Uie substance need not 

be considered in determining whether a 

threshold quantity is present. This 

exemption does not apply to: 

(i) Specialty chemical production; 

(ii) Manufacture, processing, or use of 

substances in pilot plant scale 

operations; and 

(iii) Activities conducted outside the 

laboratory. 

Subpart B—Risk Management Plan 

Requirements [Reserved] 

Subpart C—Regulated Substances for 

Accidental Release Prevention 

§68.100 Purpose. 

This subpart designates substances to 

be listed under section 112(r) (3), (4), 

and (5) ofthe Clean Air Act, as 

amended, identifies their threshold 

quantities, and establishes Uie 

requirements for petitioning to add or 

delete substances from Uie list. 

§681*20 Petition process. 

(a^ Any person may petition Uie 

Administrator to modify, by addition or 

deletion, the list of regulated substances 

identified in § 68.130. Based on the 

information presented by the petitioner, 

Uie Administrator may grant or deny a 

petition. 

(tt>) A substance may be added to the 

list if, in the case of an accidental 

release, it is known to cause or may be 

reasonably anticipated to cause death, 

injury, or serious adverse effects to 

human health or the environment. 

($) A substance may be deleted from 

the list if adequate data on Uie health 

and environmental effects of Uie 

substance are available to determine 

that Uie substance, in the case of an 

accidental release, will not cause death, 

injury, or serious adverse effects to 

human health or the environment. 

(I) No substance for which a national 

primary ambient air quality standard 

has been established shall be added to 

the list. No substance regulated under 

title VI of the Clean Air Act, as 

amended, shall be added to Uie list. 

(e) The burden of proof is on the 

petitioner to demonstrate that Uie 

criteria for addition and deletion are 

met. A petition will be denied if this 

demonstration is not made. 

§) The Administrator will not accept 

additional petitions on the same 

substance following publication of a 

final notice of the decision to grant or 

deny a petition, unless new data become 

available that could significantly affect 

Uie basis for the decision. 

Jg) Petitions to modify the list of 

regulated substances must contain the 

following: 

fl) Name and address ofthe petitioner 

and a brief description of the 

organization(s) fiat the petitioner 

represents, if applicable; 

P) Name, address, and telephone 

number ofa contact person for the 

petition; 

(3) Common chemical name(s), 

common synonym(s), Chemical 

Abstracts Service number, and chemical 

fonmula and structure; 

(4) Action requested (add or delete a 

substance); 

(5) Rationale supporting Uie 

petitioner's position; Uiat is, how the 

substance meets the criteria for addition 

and deletion. A short summary ofthe 

rationale must be submitted along with 

a more detailed narrative; and 

(6) Supporting data; that is, the 

petition must include sufficient 

information to scientifically support the 

request to modify Uie list. Such 

information shall include: 

(i) A list of all support documents; 

(ii) Documentation of literature 

searches conducted, including, but not 

limited to, identification of Uie 

database(s) searched, Uie search 

strategy, dates covered, and printed 

results; 

(iii) Effects data (animal, human, and 

environmental test data) indicating the 

potential for death, injury, or serious 

adverse human and environmental 

impacts from acute exposure following 

an accidental release; printed copies of 

the data sources, in English, should be 

provided; and 

(iv) Exposure data or previous 

accident history data, indicating Uie 

potential for serious adverse human 

health or environmental effects from an 

accidental release. These data may 

include, but are not limited to, physical 

and chemical properties of the 

substance, such as vapor pressure; 

modeling results, including data and 

assumptions used and model 

documentation; and historical accident 

data, citing data sources. 

§ 68.125 Exemptions. 

Agricultural nutrients. Ammonia used 

as an agricultural nutrient, when held 

by farmers, need not be included when 

determining whether a threshold 

quantity is present on site. 

§68.130 Ust of substances. 

(a) Explosives are covered under 

section 112(r) ofthe Clean Air Act if 

they are classified by DOT in Division 

1.1(49 CFR part 172.102) defined as 

explosives that have a mass explosion 

hazard, and are present on site in 

quantities greater than 5,000 pounds. 

(b) Regulated toxic and flammable 

substances under section 112(r) ofthe 

Clean Air Act are the substances listed 

in Tables 1, 2, 3, and 4 ofthis section. 

Threshold quantities for listed toxic and 

flammable substances are specified in 

the tables. 

(c) The bases for placing toxic and 

flammable substances on the list of 

regulated substances are explained in 

the notes to the list. 
____22_

Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5121 

TABLE 1 TO §68.130.—LIST OF REGULATED TOXIC SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEASE 

; , PREVENTION 

[Alphabetical Order—100 Substances] 

Chemical name CAS No. 

75-86-5 

107-02-8 

107-13-1 

814-68-6 

107-18-6 

107-11-9 

7664-41-7 

7664-41-7 

62-53-3 

7783-70-2 

7784-34-1 

7784-42-1 

98-87-3 

98-16-8 

98-07-7 

100-44-7 

140-29-4 

10294-34-5 

7637-07-2 

353-42-4 

7726-95-6 

75-15-0 

7782-50-5 

10049-04-4 

107-07-3 

67-66-3 

542-88-1 

107-30-2 

4170-30-3 

123-73-9 

506-77-4 

108-91-8 

19287-45-7 

110-57-6 

111-44-4 

75-78-5 

57-14-7 

2524-03-0 

106-89-8 

107-15-3 

151-56-4 

75-21-8 

7782-41-4 

50-00-0 

107-16-4 

110-00-9 

302-01-2 

7647-01-0 

74-90-8 

7647-01-0 

7664-39-3 

7722-84-1 

7783-07-5 

7783-06-4 

13463-40-6 

78-82-0 

108-23-6 

78-97-7 

126-98-7 

74-83-9 

74-87-3 

79-22-1 

60-34-4 

624-83-9 

74-93-1 

556-64-9 

75-79-6 

13463-3&-3 

7697-37-2 

10102-43-9 

98-95-3 

56-38-2 

79-21-0 

594-42-3 

108-95-2 

75-44-5 

7803-51-2 

10025-87-3 

Threshold 

quantity (lbs) 

5,000 

1,000 

10,000 

1,000 

5,000 

1,000 

1,000 

5,000 

5,000 

1.000 

5,000 

500 

1,000 

1,000 

500 

1,000 

1,000 

1,000 

1,000 

5,000 

1,000 

10,000 

1i000 

500 

1000 

10,000 

500 

1,000 

10,000 

10,000 

1,000 

5,000 

500 

1,000 

10.000 

1,000 

5.000 

1.000 

10.000 

10,000 

1,000 

5,000 

500 

500 

5,000 

1,000 

5,000 

5,000 

500 

1,000 

500 

5,000 

500 

1,000 

500 

10,000 

5,000 

5,000 

1,000 

5,000 

10,000 

1,000 

5,000 

1,000 

1,000 

10,000 

1,000 

500 

5,000 

1,000 

10,000 

1,000 

1,000 

1,000 

10,000 

500 

1,000 

1,000 

Basis lor 

listing 

P) 

P> 

C) 

p) 

P) 

P) 

(••") 

C--) 

P) 

(

b

) 

P) 

P) 

P) 

P) 

(

b

) 

p) 

p) 

p) 

p) 

p) 

M 

P) 

C-") 

P) 

p) 

p) 

p) 

p) 

p) 

p) 

P) 

p) 

P) 

p) 

p) 

P) 

p) 

P) 

p) 

p) 

p) 

P") 

p) 

p) 

p) 

p) 

p) 

p) 

n C-") 

(..») 

p) 

p) 

(..t.) 

P) 

P) 

P) 

O 

P) 

O 

O 

P) 

P) 

P") 

P) 

P) 

P) 

P) 

P) 

P) 

(') 

O 

P) 

tt 

O 

(..t.) 

P) 

P) 

Acetone cyanohydrin 

Acrolein 

Acrylonitrile 

Acrylyl chloride 

Allyl alcohol 

Allylamine 

Ammonia (anhydrous) 

Ammonia (aqueous solution, cone 20% or greater) 

Aniline 

Antimony pentafluoride 

Arsenous trichloride 

Arslne 

Benzal chloride 

Benzenamine, 3-(trifluoromethyl)-

Benzotrichloride 

Benzyl chloride 

Benzyl cyanide 

Boron trichloride 

Boron trifluoride 

Boron trifluoride compound with methyl ether (1:1) 

Bromine 

Carbon disulfide 

Chlorine 

Chlorine dioxide 

Chloroethanol 

Chloroform 

Chloromethyl ether 

Chloromethyl methyl ether 

Crotonaldehyde 

Crotonaldehyde, (E)-

Cyanogen chloride 

Cyclohexylamine 

Diborane 

Trans-1,4-dichlorobutene 

Dichloroethyl ether 

Dimethyldichlorosilane 

Dimethylhydrazine 

Dimethyl phosphorochloridothioate 

Epichlorohydrin 

Ethylenediamine 

Ethyleneimine 

Ethylene oxide 

Fluorine 

Formaldehyde 

Formaldehyde cyanohydrin 

Furan 

Hydrazine 

Hydrochloric acid (solution, cone 25% or greater) . 

Hydrocyanic acid 

Hydrogen chloride (anhydrous) 

Hydrogen fluoride 

Hydrogen peroxide (cone > 52%) 

Hydrogen selenide 

Hydrogen sulfide 

Iron, pentacarbonylIsobutyronitrile 

Isopropyl chlorolormate 

Lactonitrile 

Methacrylonitrile 

Methyl bromide 

Methyl chloride 

Methyl chlorolormate 

Methyl hydrazine 

Methyl isocyanate 

Methyl mercaptan 

Methyl thiocyanate 

Methyltrichlorosilane 

Nickel carbonyl 

Nitric acid 

Nitric oxide 

Nitrobenzene 

Parathion 

Peracetic acid 

Perchloromethylmercaptan 

Phenol (liquid) 

Phosgene 

Phosphine 

Phosphorus oxychloride 
P.23 

5122 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

TABLE 1 TO §68.130.—LIST OF f.@suLAT.tfe> TOXIC SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEASE 

PREVENTION—Continued 

[Alphabetical Order—100 Substances] 

Chemical name CAS No. 

Threshold 

quantity (lbs) 

Basis for 

listing 

Phosphorus trichloride 7719-12-2 5,000 p) 

Plperidlne 110-89-4 5,000 p) 

Proplonltrile 107-12-0 1,000 p) 

Propyl chloroformate 109-61-5 5,000 (b) 

Propylenelmlne 75-55-8 10,000 p) 

Propylene oxide 75-56-9 10,000 (b) 

Pyridine, 2-methyl-5-vlnyl- 140-76-1 1,000 (") 

Sulfur dioxide 7446-09-5 1,000 (••b) 

Sulfuric acid 7664-93-9 5,000 («) 

Sullur tetralluoride 7783-60-0 1,000 (») 

Sullur trioxide 7446-11-9 1,000 (••b) 

Tetramethyllead 75-74-1 1,000 (") 

Tetranitromethane 509-14-8 1,000 p) 

Thlophenol 108-98-5 1,000 (") 

Titanium tetrachloride 7550-45-0 500 (") 

Toluene 2,4-dllsocyanate 584-84-9 1,000 (•) 

Toluene 2,6-diisocyanate 91-08-7 1,000 (•) 

Toluene diisocyanate (unspecified Isomer) 26471-62-5 1,000 (•) 

Trichloroethylsllane 115-21-9 1,000 (") 

Trimethylchlorosilane 75-77-4 1,000 (b) 

Vinyl acetate monomer 108-05-4 5,000 (b) 

Vinyl chloride 75-01-4 10,000 (•) 

Basis lor Listing: 

'Mandated lor listing by Congress. bOn EHS list, vapor pressure O.S mmHg or greater. 

'On EHS list, vapor pressure less than 0.5 mmHg, but has been Involved In accidents resulting In death or injury. 

' Toxic gas. 

* Listed based on toxicity ot hydrogen chloride, potential to release hydrogen chloride, and history of accidents. 

TABLE 2 TO §68.130.—LIST OF REGULATED TOXIC SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEASE 

PREVENTION 

[CAS Number Order—100 Substances] 

CAS No. Chemical name Threshold 

quantity (lbs) 

Basis lor 

listing 

50-00-0 . 

56-38-2 . 

57-14-7 . 

60-34-4 . 

62-53-3 . 

67-66-3 . 

74-83-9 . 

74-87-3 . 

74-90-8 . 

74-93-1 . 

75-01-4 . 

75-15-0 . 

75-21-8 . 

75-44-5 . 

75-55-8 , 

75-56-9 . 

75-74-1 , 

75-77-4 , 

75-78-5 , 

75-79-6 , 

75-86-5 . 

78-82-0 . 

78-97-7 . 

79-21-0 , 

79-22-1 , 

91-08-7 , 

98-07-7 , 

98-16-8 , 

98-87-3 . 

98-95-3 . 

100-44-7 

106-89-8 

107-02-8 

107-07-3 

107-11-9 

107-12-0 

107-13-1 

107-15-3 

107-16-4 

107-18-6 

107-30-2 

Formaldehyde 

Parathion 

Dimethylhydrazine 

Methyl hydrazine 

Aniline 

Chloroform 

Methyl bromide 

Methyl chloride 

Hydrocyanic acid 

Methyl mercaptan 

Vinyl chloride 

Carbon disulfide 

Ethylene oxide 

Phosgene 

Propyleneimine 

Propylene oxide 

Tetramethyllead 

Trimethytchlorosi lane 

Dimethyldlchlorosl lane 

Methyttrlchlorosl lane 

Acetone cyanohydrin 

Isobutyronltrile 

Lactonltrlle 

Peracetic acid 

Methyl chloroformate 

Toluene 2,6-diisocyanate 

Benzotrichloride 

Benzenamlne, 3-(trlfluoromethyl) 

Benzal chloride 

Nitrobenzene 

Benzyl chloride 

Epichlorohydrin 

Acrolein 

Chloroethanol 

Allylamlne 

Propionitrile 

Acrylonitrile 

Ethylenediamine 

Formaldehyde cyanohydrin 

Allyl alcohol 

Chloromethyl methyl ether 

500 

000 

000 

000 

000 

,000 

,000 

,000 

500 

000 

000 

000 

000 

500 

,000 

,000 

000 

000 

000 

000 

000 

000 

000 

,000 

,000 

,000 

500 

,000 

,000 

,000 

,000 

,000 

,000 

,000 

,000 

000 

000 

000 

,000 

000 

000 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

(•) 

P

b

) 

p) 

p) 

p) 

(-") 

p") 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 

p) 
P.24 

Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5123 

TABLE 2 TO §68.130.—LIST OF REGULATED TOXIC SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEASE 

PREVENTION—Continued 

[CAS Number Order—100 Substances] 

CAS No. Chemical name Threshold 

quantity (lbs) 

5,000 

5,000 

5,000 

10,000 

1,000 

5,000 

1,000 

1,000 

5,000 

10,000 

1,000 

10,000 

1,000 

1,000 

1,000 

1,000 

5,000 

5,000 

1,000 

1,000 

500 

10,000 

1,000 

1,000 

1,000 

1,000 

1,000 

10,000 

1,000 

1,000 

500 

1,000 

1,000 

5,000 

500 

1,000 

5,000 

5,000 

5,000 

5,000 

5,000 

1,000 

500 

1,000 

1,000 

500 

1,000 

1,000 

5,000 

500 

1,000 

1,000 

500 

1,000 

1,000 

500 

500 

500 

1,000 

Basis for 

listing 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

C) 

P) 

P") 

P) 

P) 

P) 

P") 

pt.) 

P) 

P) 

P") 

P) 

(••") 

P

b

) 

P") 

P) 

P) 

P) 

P) 

P") 

P) 

P

b

) 

P

b

) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

P) 

108-05-4 .... 

108-23-6 .... 

108-91-8 .... 

108-95-2 .... 

108-98-5 

109-61-5 

110-00-9 

110-57-6 .... 

110-89-4 .... 

111-44-4 .... 

115-21-9 .... 

123-73-9 .... 

126-98-7 .... 

140-29-4 .... 

140-76-1 .... 

151-56-4 .... 

302-01-2 .... 

353-42-4 .... 

506-77-4 .... 

509-14-8 .... 

542-88-1 .... 

556-64-9 .... 

584-84-9 .... 

594-42-3 .... 

624-83-9 .... 

814-68-6 .... 

2524-03-0 .. 

4170-30-3 .. 

7446-09-5 .. 

7446-11-9 .. 

7550-45-0 .. 

7637-07-2 .. 

7647-01-0 .. 

7647-01-0 .. 

7664-39-3 .. 

7664-41-7 .. 

7664-41-7 .. 

7664-93-9 .. 

7697-37-2 .. 

7719-12-2 .. 

7722-84-1 .. 

7726-95-6 .. 

7782-41-4 .. 

7782-50-5 .. 

7783-06-4 .. 

7783-07-5 .. 

7783-60-0 .. 

7783-70-2 .. 

7784-34-1 .. 

7784-42-1 .. 

7803-51-2 .. 

10025-87-3 

10049-04-4 

10102-43-9 

10294-34-5 

13463-39-3 

13463-40-6 

19287-45-7 

26471-62-5 

Vinyl acetate monomer 

Isopropyl chloroformate 

Cyclohexylamine 

Phenol (liquid) 

Thlophenol 

Propyl chloroformate 

Furan 

Trans-1,4-dichlorobutene 

Piperidine 

Dichloroethyl ether 

Trichloroethylsi lane 

Crotonaldehyde, (E) 

Methacrylonitrile 

Benzyl cyanide 

Pyridine, 2-methyl-5-vlnyl 

Ethyleneimine 

Hydrazine 

Boron trifluoride compound with methyl ether (1:1) . 

Cyanogen chloride 

Tetranitromethane 

Chloromethyl ether 

Methyl thiocyanate 

Toluene 2,4-diisocyanate 

Perch- loromethylmer- captan 

Methyl isocyanate 

Acrytyl chloride 

Dimethylphosphorochloridothloate 

Crotonaldehyde 

Sulfur dioxide 

Sulfur trioxide 

Titanium tetrachloride 

Boron trifluoride 

Hydrogen chloride (anhydrous) 

Hydrochloric acid (solution, cone 25% or greater) ... 

Hydrogen fluoride 

Ammonia (anhydrous) 

Ammonia (aqueous solution, cone 20% or greater). 

Sulfuric acid 

Nitric acid 

Phosphorus trichloride 

Hydrogen peroxide (cone > 52%) 

Bromine 

Fluorine 

Chlorine 

Hydrogen sulfide 

Hydrogen selenide 

Sulfur tetrafluoride 

Antimony pentafluoride 

Arsenous trichloride 

Arslne 

Phosphine 

Phosphorus oxychloride 

Chlorine dioxide 

Nitric oxide 

Boron trichloride 

Nickel carbonyl 

Iron, pentacarbonyl 

Diborane 

Toluene diisocyanate (unspecified Isomer) 

Basis tor Listing: 

" Mandated for listing by Congress. b

 On EHS list, vapor pressure O.S mmHg or greater. 

• On EHS list, vapor pressure less than O.S mmHg, but has been Involved In accidents resulting In death or Injury. 

* Toxic gas. 

• Listed based on toxicity ol hydrogen chloride, potential to release hydrogen chloride, and history of accidents. 

TABLE 3 TO §68.130.- -LIST OF REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL 

RELEASE PREVENTION 

[Alphabetical Order—62 Substances] 

Chemical name CAS No. 

Threshold 

quantity (lbs) 

Basis for 

listing 

Acetaldehyde 

Acetylene 

Bromotri- fluorethylene 

1,3-Butadlene 

75-07-0 

74-86-2 

598-73-2 

106-99-0 

10,000 

10,000 

10,000 

10,000 
• I ppi " 

" T 

P.25 

5124 Federal Register / Vol. 5 ^ No. 11 / Tuesday, January 19, 1993 / Proposed Rules 

TABLE 3 TO §68.130.^LIST ©F REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL 

RELEASE PREVENTION—Continued 

[Alphabetical Order—62 Substances] 

Chemical name CAS No. 

Threshold 

quantity (lbs) 

Basis for 

listing 

Butane 106-97-8 10,000 

1-Butene 106-98-9 10,000 

2-Butene 107-01-7 10.000 

Butene 25167-67-3 10,000 ft 

2-Butene-cls 590-18-1 10,000 

2-Butene-trans 624-64-6 10,000 ft 

Carbon oxysulfide 463-58-1 10,000 

Chlorine monoxide 7791-21-1 10,000 

2-Chloropropylene 557-98-2 10,000 

1-Chloropropylene 590-21-6 10,000 

Cyanogen 460-19-5 10,000 ft 

Cyclopropane 75-19-4 10,000 ft 

Dlchlorosilane 4109-96-O 10,000 ft 

Difluoroethane 75-37-6 10,000 ft 

Dimethylamine 124-40-3 10,000 

2,2-Dlmethylpropane 463-82-1 10,000 

Ethane 74-84-0 10,000 ft 

Ethyl acetylene 107-00-6 10,000 ft 

Ethylamlne 75-04-7 10,000 ft 

Ethyl chloride 75-00-3 10,000 ft 

Ethylene 74-85-1 10,000 

Ethyl ether 60-29-7 10,000 

Ethyl mercaptan 75-08-1 10,000 

Ethyl nitrite 109-95-5 10,000 ft 

Hydrogen 1333-74-0 10,000 ft 

Isobutane 75-28-5 10,000 

Isopentane 78-78-4 10,000 

Isoprene 78-79-,'i 10,000 

Isopropylamine 75-31-0 10,000 

Isopropylchloride 75-29-6 10,000 

Methane 74-82-8 10,000 ft 

Methylamine 74-89-5 10,000 ft 

3-Methyl-1-butene 563-45-1 10,000 

2-Methyl-1-butene 563-46-2 10,000 

Methyl ether 115-10-6 10,000 

Methyl formate 107-31-3 10,000 

2-Methylpropene 115-11-7 10,000 ft 

1,3-Pentadiene 504-60-9 10,000 ft 

Pentane 109-66-O 10,000 

1-Pentene 109-67-1 10,000 

2-Pentene, (E)- 646-04-8 10,000 

2-Pentene, (Z)- 627-20-3 10,000 

Propadiene 463-49-0 10,000 ft 

Propane 74-98-« 10,000 ft 

Propylene 115-07-1 10,000 ft 

Propyne 74-99-7 10,000 ft 

Silane 7803-62-5 10,000 ft 

Tetrafluoroethylene 116-14-3 10,000 ft 

Tetramethylsllane 75-76-3 10,000 

Trichlorosilane 10025-78-2 10,000 

Trifluoro- chloroethylene 79-38-9 10,000 ft 

Trimethylamine 75-50-3 10,000 ft 

Vinyl acetylene 689-97-4 10,000 ft 

Vinyl ethyl ether 109-92-2 10,000 (•) 

Vinyl fluoride 75-02-5 10,000 

Vinylidene chloride 75-35-4 10,000 

Vinylidene fluoride 75-38-7 10,000 ft 

Vinyl methyl ether 107-25-5 10,000 ft 

Basis tor Listing: 

'Flammable gas. 

• Volatile flammable liquid. 

TABLE 4 TO §68.130.—LIST OF REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTIAL 

RELEASE PREVENTION 

[CAS Number Order—62 Substances] 

CAS No. Chemical name Threshold 

quantity (lbs) 

Basis for 

listing 

60-29-7 

74-82-8 

74-84-0 

74-85-1 

74-86-2 

74-89-5 

74-98-6 

Ethyl ether... 

Methane 

Ethane 

Ethylene 

Acetylene .... 

Methylamine 

Propane 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 
P.26 

Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules 5125 

TABLE 4 TO §68.130.- -LIST OF REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTIAL 

RELEASE PREVENTION—Continued 

[CAS Number Order—62 Substances] 

CAS NO. Chemical name Threshold 

quantity (lbs) 

Basis for 

listing 

74-99-7 

75-00-3 

75-02-5 

75-04-7 

75-07-0 

75-08-1 

75-19-4 

75-28-5 

75-29-6 

75-31-0 

75-35-4 

75-37-6 

75-38-7 

75-50-3 

75-76-3 

78-78-^1 

78-79-5 

79-38-9 

106-97-8 .... 

106-98-9 .... 

106-99-0 .... 

107-00-6 .... 

107-01-7 .... 

107-25-5 .... 

107-31-3 .... 

109-66-0 .... 

109-67-1 .... 

109-92-2 .... 

109-95-5 .... 

115-07-1 .... 

115-10-6 .... 

115-11-7 .... 

116-14-3 .... 

124-40-3 .... 

460-19-5 .... 

463-49-0 .... 

463-58-1 .... 

463-82-1 .... 

504-60-9 .... 

557-98-2 .... 

563-45-1 .... 

563-46-2 .... 

590-18-1 .... 

590-21-6 .... 

598-73-2 .... 

624-64-6 .... 

627-20-3 .... 

646-04-8 .... 

689-97-4 .... 

1333-74-0 .. 

4109-96-O .. 

7791-21-1 .. 

7803-62-5 .. 

10025-78-2 

25167-67-3 

Propyne 

Ethyl chloride 

Vinyl fluoride 

Ethylamine 

Acetaldehyde 

Ethyl mercaptan 

Cyclopropane 

Isobutane 

Isopropyl chloride 

Isopropylamine 

Vinylidene chloride 

Difluoroethane 

Vinylidene fluoride 

Trimethylamine 

Tetramethylsilane 

Isopentane 

Isoprene 

Trifluorochloroethylene 

Butane 

1-Butene 

1,3-Butadiene 

Ethyl acetylene 

2-Butene 

Vinyl methyl ether 

Methyl formate 

Pentane 

1-Pentene 

Vinyl ethyl ether 

Ethyl nitrite 

Propylene 

Methyl ether 

2-Methylpropene 

Tetrafluoroethylene 

Dimethylamine 

Cyanogen 

Propadiene 

Carbon oxysulfide 

2,2-Dlmethylpropane .... 

1,3-Pentadiene 

2-Chloropropylene 

3-Methyl-l -butene 

2-Methyl-1-butene 

2-Butene-cis 

1-Chloropropylene 

Bromotrifluorethylene ... 

2-Butene-trans 

2-Pentene, (Z) 

2-Pentene, (E) 

Vinyl acetylene 

Hydrogen 

Dichlorosilane 

Chlorine monoxide 

Silane 

Trichlorosilane 

Butene 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

10,000 

Basis for Listing: 

'Flammable gas. 

'Volatile flammable liquid. 

[FR Doc. 93-960 Filed 1-15-93; 8:45 am] 

BILUNQ CODE 6560-50-M