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

ENVIRONMENTAL PROTECTION
AGENCY

40 CFR Part 68
[A-91-7468: FRL-4553-3]

List of Regulated Substances and Thresholdsfor Accidental Release Prevention; Requirements for Petitions under Section 112(r) ofthe Clean Air Act as Amended
AGENCY: Environmental Protection Agency (EPA). ACION: Proposed rule.

SUMMARY: The Clean Air Act Amendments of1990, signed into law

on November 15, 1990, include provisions for chemical accident prevention. The Environmental Protection Agency is proposing a listof regulated substances and threshold quantities as required under section 112(r) ofthe Clean Air Act as amended. The list is composed ofthree distinct categories: list of100 toxic substances, list of62 flammable substances (gases and volatile liquids), and commercial explosives as defined by the Department ofTransportation (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 ofaccidental releases to be proposed later. EPA is also publishing the requirements forthe petition process that will be used to add or delete chemicals from the final list. DATES: Comments mustbe 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 forpublic 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 and Prevention Office, OS-120, Environmental Protection Agency, 401 M St. SW., Washington, DC 20460, or theEmergency Planning and Community Right-to-Know Hot Line at 1-800-535-0202. SUPPLEMENTARY INFORMATION: I.Introduction

A. Statutory Authority B.Background I. Clean Air Act Amendments of1990 (CAAA) III. List ofSubstances and Thresholds

A. Introduction B.Factors Considered in Defining List

Criteria C.Criteria Options Considered D.List ofSubstances E.Threshold Quantities IV.Other Issues

A. StatePrograms B.OSHA's List ofHighly Hazardous

Chemicals C. Relationship to EPCRA (SARA Title III)

Section 302/303 D.Agricultural Nutrient Exemption E.Information Gathering Efforts V.Petitions for Additions and Deletions

A. Information Required fron Petitioner B.Petition Process VI. Discussion ofthe Proposed Rule VII. Required Analyses

A. E.O. 12291 B.Regulatory Flexibility Act C. Paperwork Reduction Act

I. Introduction

A. StatutoryAuthority

This notice ofproposed rulemaking (NPRM) is being issued under section 112(r) ofthe Clean Air Act (CAA or Act)

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

B.Background

Public awareness ofthe potential danger from accidental releases of hazardous chemicals has increased over the years as serious chemical accidents have occurred around the world (e.g., the 1974 explosion in Flixborough, England, and the 1976 release of dioxin in Seveso, Italy). Public concern intensified following the 1984 release of methyl 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.

In response to this public concern and the hazards that exist, the U.S. Environmental Protection Agency (EPA) began its Chemical Emergency Preparedness Program (CEPP) in 1985,

as part ofthe Agency's Air Toxics Strategy. CEPP was a voluntary program to encourage state and local authorities
to identity hazards in their areas and to plan for chemical emergency response actions. In 1986, Congress adopted many ofthe elements ofCEPPin the Emergency Planning and Community Right-to-Know Act of1986 (EPCRA), also known as Title I ofthe Superfund Amendments and Reauthorization Act of 1986 (SARA TitleII). EPCPA (SARA Title Ill) requires states to establish state and 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 I) 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 ofboth the emergency response plans and the public-industry dialogue on risks andrisk reduction.

EPCRA (SARA Title III) did not mandate that facilities establish accident prevention programs. However, Congress acknowledged the importance ofaccident prevention by requiring EPA, under EPCRA (SARATitle 11I) section 305(b), to conduct a review of emergency systems to monitor, detect, and prevent chemical accidents. The final report to Congress, Reviewof EmergencySystems (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 TitleII) did not directly address accident prevention, EPA recognized that prevention, preparedness, and response form acontinuum. Therefore, in 1986, EPA established a chemical accident prevention program to collect information on chemical accidents and' work with other groups to increase knowledge ofprevention 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 ofchemical accidents and the steps facilities take toprevent
recurrences. EPA also developed a program forconducting chemical safety audits at facilities. Through the audit program, EPA headquarters and regional staff aswell 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 howbest toreach smaller operations, which the section 305(b) study indicated are less 5102

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aware ofrisks than larger facilities. EPA has also been an active participant in international efforts related to chemical accident prevention, particularly through the Organization forEconomic 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 FR6356, 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 ofChemical Engineers has published guidance on the management ofchemical 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 AirAct Amendments of 1990 (CAAA)

In the Clean AirAct 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 ofthe 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) of the CAA has a number ofprovisions. 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 ofthe quantity oj substances managed at the facility. Activities such

ashazards identification using appropriate hazard assessment techniques, designing, maintaining and operating a safe facility, and minimizing the consequences ofaccidental releases ifthey occur would be essential activities that must beperformed to satisfy the general duty requirements. Owners and operators ofthese stationary sources are required in the CAA to conduct, in the samemanner and to the same extent as OSHA's general duty clause in section 654 of title 29 ofthe United States Code, these activities as a matter ofgeneral business practice.

Section 112(r)(3) ofthe CAA requires EPA to promulgate, by November 15, 1992, a listof atleast 100 substances ("regulated substances") that are known to cause, ormay be reasonably anticipated to cause, death, injury, or serious adverse effects to human health

or the environment ifaccidentally 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 ofaccidental releases and for responses to such releases. The accident prevention regulations will apply to stationary sources that have present
more than a threshold quantity ofa 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 ofpersonnel in theuse and maintenance ofequipment 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 forthe Risk Management Program requirements will bepublished in the Federal Registerin the future.

The Act establishes a Chemical Safety and Hazard Investigation Board to investigate (orcause 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 empl6yees from hazards associated with accidental releases ofhighly hazardous chemicals in the workplace. OSHA promulgated a final rule (57 FR 6356, February 24, 1992) requiring achemical 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 ofhighly hazardous toxic and reactive substances at particular threshold quantities, flammable liquids orflammable gases in quantities of 10,000 pounds ormore and to the manufacture ofexplosives and pyrotechnics.
III.Listof Substances andThresholds
A. Introduction

The Act requires EPA to promulgate,

no later than November 15, 1992, an initial listof at least 100 substances that, in the event ofan 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 theAct 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 ofextremely hazardous substances (EHSs) promulgated under EPCRA (SARA Title III) section 302.

Congress listed the following 16 substances tobe 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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No air pollutant forwhich anational Erimary ambient airquality standard

asbeen established shall beincluded

onthe list, withthe exception of anhydrous sulfur dioxide and sulfur trioxide, which must be included.No substances regulated under title VI of the Act asamended shall beincluded

on the list. Title VIcovers ozone depleters, primarily chlorofluorocarbons (CFCs)and halons.

The list ofchemicals proposed today will, when final. identstationary

sources that will becovered bychemical accident prevention regulations subsequently adopted under section 112(r) ofthe Act.The list ofsubstances is intended to focusaccidental release prevention efforts on those stationary

sources and substances thatpose significant hazards to thecommunity. EPA strongly emphasizes, however, that the chemicals proposed today for listing

are notthe only substances thatmay pose a threat to communities upon release. There are large numbers of compounds and mixtures in commerce in theUnited Statesthat in specific circumstances could be considered toxic

orotherwise dangerous; however, it would notbe feasible to Include all such substances and circumstanoes. The proposed list represents only the first step toward development ofan effective accidental release prevention effort by facilities.Without a preliminary list of thiskind, Itwould bemore 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 alist ofall substances that could be considered forchemical accident prevention. Similarly, thethreshold quantitiesbeing proposed maynot always represent a level below whichno hazard exists. Although stationary

sources will be required to comply with the provisions for accidental release prevention only iftheyhave listed substances in quantities exceeding the threshold quantity, it does not mean that these substances in smaller quantities represent nopotential hazard to the community. Also.stationary

sources have ageneral duty tocomply and perform activities toprevent and mitigate accidental releass regardless of the quantityofthe substance handled

on site.

EPA is proposing a list of100 acutely toxic substances, 62 flammnablegases and volatile flammable liquids, and high explosives as a category.Proposed threshold quantities for toxic substances

arebased ona ranking method that considers each substance' tocicity and potential to become airborne and disperse. The proposed threshold quantity for flammable substances Is based onthequantity that potentially mightbe involved in a vapor cloud explosion.Theproposed threshold quantity for high explosives is based on the quantity that could produce potentially lethal blast waves from an explosion at a distance of 100meters. The presence ofa threshold quantity at

a stationary sourcewould be determined based on the maximum quantity in a single process. B. FactorsConsidered inDefining List Criteria

Under CAA section 112(rX4), the factors to beconsidered inlisting substances are: (a)The severity ofacute adverse health effects associated with accidental releases ofthe substance, (4) the likelihood ofaccidental releases of the substance, and (c)thepotential magnitude ofhumanexposure to accidental releases ofthe substance. The Act specifies that the Administrator shalluse, butis not limited to,the list ofextremely hazardous substances (EHSs)under EPCRA (SARATitle III) section 302 forpurposes of promulgatingthe list.The Act also requiresthatregulations establishing the list shall include an explanation ofthe basis for establishing the list.

EPAreviewed anumber ofexisting or proposed chemical lists associated with other accident prevention, preparedness and response programsto evaluate criteria forlisting regulated substances. These lists, which are related to safety and the protection ofhuman health and the environment, included several EPA lists, listsdeveloped by other Federal agencies, lists developed under state programs, and lists developed under international programs.

The chemical lists reviewed were: * The EPCRA (SARATitle II) Section 302 List ofExtremely Hazardous Substances

9 TheEPCRA (SARA Title II)Section 313 List ofToxic Chemicals

9 The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section 102Hazardous Substances List

a The Clean AirAct Section 112(b) List ofHazardous AirPollutants

e The Department ofTransportation's (DOT)Toxic by Inhalation Lists

o OSHA'sProposed List forProcess Safety Management Regulations1

* The New Jersey Acute Toxic Catastrophe List

SEPA'sanalysiswas based on OSHA'sproposed reISSPR29150,Muy 7,1"go. OSHAbA since publ~eG Bad .mad7 sr R63S6, f ry 24Ae * TheList fromthe European Community's (EC) Seviso Directive (subsequentlyrevised)

* The Delaware Prevention Regulations List

* The National FireProtection Association's (NFPA) Fire Hazard Properties ofFlammable Liquids, Gases, and Volatile Solids

* Flammable Gases and Volatile Flammable Liquids fromthe DOT Hazardous Materials Table

Thecriteria usedfor the development ofthese lists werereviewed to determine whethertheywere related to the factors mandated by Congress forlist development underCAA section 112(r). Acute toxicity wasgenerally considered in developing these lists ofchemicals. but soew also used flammability and explosivity as criteria forregulating chemicals. Several lists used a measure ofdispersibility (equilibrium vapor pressure)incombination with acute toxicity.Furthermore, some programs used,either exclusively orin part, criteriarather than liststodefine coveredchemicals.

The EPCRA ISARA Title 11) section 302 list,the DOT toxicby inhalation list, the New Jersey acute toxic catastrophe list, the Delaware prevention regulations list.andthe list from the European Community's (EC} Seveso Directiveare all based on some
measures oftoxicity and thepotential for achemical tobecome airborne. The CERCLA list isnotbased solelyon an airborne citerion, butrather Isbasedon
a combination ofstatutory requirements and criteria. OSHA's listis based ona reviewofchemical listscompiled by a number ofFederal and state agencies and other organizations [LB.. EPA. DOT, the World Bank, NFPA, the Healthand Safety Commission ofthe United Kingdom. and the states ofDelaware andNewJersey) and itincludes chemicals listed fortoxicity and reactivity, as well as criteria listings for flammability andexplosivity. NFPA~s list was developed bycommittee and includes a compilation ofdate from various sources. Listed chemicals are ranked according totheir flammability. reactivity, and health hazards, the flammabilityrankings ambased primarily on flash point adboiling point. EPA reviewed theDOT Hazardous Materials Table, whichlists materials regulated in transportation, to identify flammable substances The HazardousMaterials Table includes hazard classes and packing assigned according tothe

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EPA's review ofthe CAA section 112(b) list ofhazardous air pollutants and ofthe EPCRA (SARA Title III) section 313 list oftoxic chemicals indicated thatboth ofthese lists focus

on routine emissions rather than accidental releases. The CAA section 112(b) list is aimed at controlling routine emissions ofhazardous 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 ofthese lists include chemicals that have adverse health effects from shortterm exposure, the majority ofthe 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 ofan accidental release. Therefore, EPA determined that the CAA section 112(b) 'list and the EPCRA (SARA Title I) section 313 list were not ofparticulr 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, theAgency set out to define these factors more specifically in relation to accidental releases. The Agency's definitions are discussed below. Severity ofAcute Adverse Health Effects

The severity of acute adverse health effects can be related to the inherent hazards ofthe substances ofinterest, such as the toxicity ofa substance resulting in lethal effects. Accidental releases would most likely lead to shortterm exposure ofthe 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 ofthe substance, or whether the substance is highly reactive. The phenomena associated with these hazards could be, for example, radiant heat from a chemical fire orblast waves from an explosion of

a chemical.

As confirmed by a review ofdeath 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) ofreleased substances are important factors in the actual severity ofthe 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 ofhuman exposure (discussed below), EPA is proposing to give these factors substantial weight in selecting its proposed list ofregulated substances.

Likelihood ofRelease

There are many measures and surrogates that can be used to define the likelihood ofan accidental release. The likelihood ofa 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 ofgreater handling and use, may have a greater potential for

an accidental release. A history ofa large number ofaccidents in the past, for example, may be an indicator ofan 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 ofaccidental 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 ofequipment) in criteria for a national list.

Likelihood can also be related to the possibility ofthe chemical becoming airborne and having an effect beyond the facility fenceline in the event ofan 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 non- volatile liquids to become airborne in an explosion, gaseous substances and vapors from volatile liquids are more likely to bereleased to air and have an effect beyond the facility fenceline. Because the chemical and physical properties ofthe substances under review are linked to both the likelihood and the severity ofchemical accidents, EPA believes that these two factors deservethe greatest weight in determining its proposed listof substances. EPA solicits comments on other factors accounting for severity and likelihood ofa release that might be used to determine the list of substances. EPA also solicits comments on the availability ofdata to support the use of such factors. Magnitude ofHuman Exposure

For purposes oftoday's proposal EPA considers the magnitude ofhuman exposure associated with accidental releases to be related to the severity of the health effects (hazards)and the likelihood ofa release (the likelihood that a release will have an effect on the population orenvironment beyond the facility fenceline). This definition of magnitude of exposure Is somewhat different from the traditional risk assessment definition ofhuman 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 ofusing the Agency's approach

as a surrogate measure ofthe magnitude ofhuman and environmental exposure and requests commenters to submit any suggested method for determining magnitude ofhuman or environmental exposure to accidental releases of hazardous substances.

The Agency recognizes factors that might affect the magnitude ofhuman exposure could be site-specific or accident-specific, and could varywidely 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 touse 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 ofsubstances.

EPA has also estimated, through analysis ofinformation collected through the Accidental Release Information Program (ARIP) database for

some ofthe listed toxics, the likelihood that releases ofthose 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 5105

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precisely known and isnot predictable with any degree ofconfidencebecause ofmany site-specific factors that influence the result. However, for purposes ofthisproposal, the level of severity ordegree ofhazard for the particular substance that generated the off-site impact isknown such that the severity ofthe health effect and the likelihood ofrelease has been usedas a surrogate forthe actual human exposure level. EPA requests comments and any additional data which could improve

our assessment ofhuman exposure. C. CriteriaOptionsConsidered

The CAA mandates EPAto develop a list of substances based on specified criteria, namely severity ofadverse health effects, likelihood ofaccidental releases, and potential magnitude of human exposure. TheAct also mandates the inclusion of16 substances in this list; these substances serve as the starting point for the development ofthe full-listofregulated-substances. The Agency identified additional substances based on similarities with themandated substances and the selection criteria specified in the Act. The options considered for the selection criteria accounted for the inherent hazards of thesubstances tobe listed, as well as for thepotential these hazards have to affect thecommunity in case of an accidental release. The hazards considered include toxicity, flammability, reactivity, explosivity, and radioactivity, all ofwhich can result in acute effects from short term exposures. Substances were identified for each ofthese hazards, but, in addition, the Agency considered the potential impact that the identified substances would have on the community incase ofa release. Each hazard, and its potential topose a threat to the community, was evaluated independently of any other hazard, because ofthe difficulties ofaddressing all possible combinations ofhazards. A .group oftoxic substances, agroup 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 proposingto focus on acute effects from short-term exposure to toxics as one priority for development of this listbecause these effects are believed tobe ofimmediate concern beyond the fenceline in case ofan accidental release. EPA isproposing to list 100 acutely toxic substances. EPA is also proposing to consider the physical hazards of flammable and explosive substances because theseeffects may have an impact on the community beyond thefnameine intheevent ofan accidental release. For flammable chemicals, EPA is focusing on the effects ofblast waves from vapor cloud explosions, because such effects appear to have the potential to affect the community beyond the fenceline. A list of62 flammable gases and volatile flammable liquids isproposed. EPA considers commercial high explosives, which have the potential to detonate, to bethe explosive substances with the greatest potentialto affect the community; commercial high explosives

are proposed for listing as acategory. EPA also considered, based on analyses ofaccident history data, the relationship between past accidental releases of toxic, flammable, and explosive substances and their associated human and environmental effects, as atool 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 (orimported) or that are not handled in commercial quantities.

1. Toxicity.

To account for the severity ofacute health effects from accidental releases of toxic chemicals, EPA is proposing to list

a subset ofthe chemicals already identified as EHSs on the basis of acute toxicity (lethality) under EPCRA (SARA Title Il) section 302. For purposes of criteria for listing, severity ofacute adverse health effects from toxic chemicals was considered to bebest measured by the concentration or dose level that could cause death or serious, irreversible health effects after a short exposure. Chemicals not on the EHS list, but listed under otherprograms, also were reviewed to determine whether there were other chemicals that should be considered for listing on the basis oftheENS 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 oftheir
acute toxicity. The listhas been revised

over the years based on reviews of toxicity data.EPA believes that theEHS 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 ofanimal test data, using thecriteria listed below. These criteria are discussed in more detail in TechnicalGuidance forHazards Analysis(December 1987). aguidance document developed by EPA in conjunction with the Federal Emergency Management Agency (FEMA) and DOT. EPA also included on the EPCRA (SARA Title 11) section 302 list chemicals that are less toxic than those meeting these criteria but, because of theirknown toxicity and high production volume, maypose a threat to the community.

The acute toxicity criteria are: Inhalation LCse-0.5 milligrams perliter ofair (for-exposure time!8 hours),

or Dermal LDWe50 milligrams per kilogram ofbody weight, or Oral LDs:e.25 milligrams perkilogram of body weight where LCso is the median lethal concentration, or the concentration in air at which 50percent ofthe test animals died, and LD59 is the median lethal dose, orthe dosethat killed 50 percent ofthe testanimals. In the absence ofLC 5oorLDo data, LCLo or LD data were used for listing, where LCLoL the lethal concentration low, or the lowest concentration in air atwhich any test animals died, and LD.is the lethal dose low, or the lowest dose that killed any testanimals.

In addition, EPA chose to focus on physical state, vaporpressure, and accident historyin setting criteria related to the likelihood ofaccidental releases fortoxic chemicals. A vapor pressure criterion of0.5 millimeters of mercury (mim Hg) under ambient conditions is proposed fortoxic liquids. This criterion captures mosttoxic substances that have relatively low volatility but may still pose an airborne hazard in case ofan accidental release. Congress mandated the listing of toluene diisocyanate, which has a relatively low ambient vaporpressure; therefore, EPAbelieves itis appropriate to setthe vapor pressure criterion at a level that would include onthe list other toxic liquids with relatively low volatility, similarto toluene diisocyanate that alsohave accident history. Chemicals on the EHS list that

are gases under ambient conditions and liquids meeting the vaporpressure criterion of0.5 mm Hg were considered for listing. Additional chemicals were identified on the basis ofhigh 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 ofaccident prevention

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damaging and environmental effects. Using theARIP data, EPA developed estimates ofthe probabilities that releases ofthose toxic substances reported through ARIP would result in human or environmental impacts. In this way, EPA attempted to measure the potential magnitude ofthe impacts resulting from an accidental release ofa listed toxic substance as itrelates to certain chemical accident prevention requirements at facilities that handle these substances. EPA seeks comments

on which type ofdata (i.e., relationship between accidental releases and human and environmental impacts, accident history, physical/chemical properties)

orcombination ofdata could be used to evaluate the magnitude ofhuman exposure fortoxics.

EPA is focusing on acute toxicity to identity toxic chemicals as a priority for listing,because acute toxicity is ofthe most immediate concern in an accidental release. However, there are a number ofother possible health effects criteria that might be considered ata future time for listinghazardous 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 ofthese health effects and onhow to rank substances listed onthese bases.

2. Flammability

EPA also considered physical hazards ofchemicals in relation to acute health effects. EPA Is currently reviewing the EPCRA (SARA TitleM) section 302 list ofchemicals and considering the addition ofchemicals to that list based

on explosivity, flammability, and reactivity. EPA has published an advance notice ofproposed rulemaking (55FR 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 forlisting today based on the analysis conducted in its review ofthe EPCRA (SARA Title 11I) section 302 list.The analysis of flammables and explosives conducted in support oflisting under section 302 has been reviewed by EPA's Science Advisory Board. Results ofadditional analysis that may be carried out as a result ofthat review in support ofthe EPCRA (SARA TitleIII) section 302 list review will beconsidered priorto publication ofa finalrule. EPA's analysis ofhistorical data on accidental releases offlammable chemicals indicate that vapor cloud explosions may pose the most serious hazard from a flammable substance to the community. The heat effects ofa fire involving a flammable liquid or gas, or ofa fireball from aboiling liquidexpanding vapor explosion (BLEVE), do not have a severe impact foras great a distance from the source as theblast effects ofavapor cloud explosion ofthe

same quantity ofa 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 onthe results ofEPA modeling offlammable hazards and analysis ofthe literature, aclear distinction can be made between the results for flammable substances that boil attemperatures below approximately 370 C and higher boiling flammable substances. Analysis ofother classification schemes and regulations indicates that flammable gases and volatile flammable liquids arethe flammable materials considered of greatest concern by agencies and organizations such asDOT, NFPA, and EEC.The temperature at which clear distinctions in consequences can be made, based on modeling techniques, corresponds to the temperature atwhich DOT and NFPA have made distinctions in categories of flammable materials (boilingpointbelow 380Cand flash point below 23*C for NFPA flammability rating 4; boiling point below 35 0C and flash pointbelow 230C for DOTpacking group I).EPA decided
to use the criteria used by NFPA for flammable gases and liquids withthe highest degree ofhazard (aranking of4) forflammability toidentify flammable substances. Flammable liquids with a flash point below 730F (22.80C) and a boiling point below 100'F (37.8°C), as well asflammable 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 ofaccidental releases offlammable substances. The volatility ofa flammable substance istaken into accountby 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 ofthese effects and on the ranking ofthese 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 forthis basis. However, unlike the accident database for toxic substances, EPA does not have a database from whichto estimate directly

arelationship 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 Agencybelieves that the accident prevention measures that have proven effective at facilities that handle toxic substances willbe as effective at facilities thathandle flammable substances. EPA requests comments and any data that the public

can provide to directly estimate the relationship between the presence or absence ofaccident prevention

measures at facilities where accidental releases ofthese substanceshave occurred and the probability that human and environmental Impacts will occur. EPA also seeks comments on which type ofdata (i.e., relationship between accidental releases andhuman and environmental impacts, accident history, physical/chemical properties)

or combination ofdata could be used to evaluate the magnitude ofhuman exposure for flammables.
3. Explosivity

Explosives are already regulated by several agencies and organizations. The Bureau ofAlcohol, Tobacco, and Firearms (BATF)regulates the manufacture, processing, use, distribution, and storage ofexplosive materials; BATF regulations include licensing, permitting, and recordkeeping requirements and requirements for storage ofexplosives. DOTregulates the transportation ofexplosives, and other agencies such asOSHA, the Mine Safety and Health Administration (MSHA), the Department ofDefense (DOD), and the International Maritime Organization (IMO) regulate certain aspects ofthe explosives industry.Many state and local governments alsohave regulations regarding licensing and safety 5107

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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 ofan accidental explosion. Although explosives are currently regulated by Federal, state, and local governments, these regulations do not uniformly address the issue ofidentifying hazards using appropriate hazard assessment. techniques, designing and maintaining a safe facility, and minimizing the
consequences ofaccidental releases when they do occur. All ofthese 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 oflist development and accidental release prevention regulations.

Blast waves from accidental explosions have the potential to cause damage to people and property beyond the fenceline. EPAconsidered high explosives, low explosives, and blasting agents in its analysis ofthe hazards of explosives. High explosives are generally defined as those materials that detonate ifignited, shocked, or subjected to heat or friction. Detonations result from chemical reactions that proceed at supersonic velocities, generating large volumes ofhigh
pressure gas and heat instantaneously,

even though no confining vessel or structure exists. In an explosion caused by a high explosive, the rate ofenergy release is particularly rapid and the shock wave has a very short duration time. In contrast, low explosives deflagrate, or bum 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 ofgas and heat) or which, by chemical reaction within itself, is able to function in a similar manner

even ifnot designed to function by explosion *

.... "High explosives are classified by DOT in Division 1.1, defined asexplosives that have a mass explosion hazard, where a mass explosion hazard is onethat affects almost the entire load instantaneously. Low explosives, Division 1.3 under DOT, are defined as explosives that have a firehazard and either a minor blasthazard or aminor projection hazard orboth, but nota 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 oftransition from burning to detonation under normal conditions oftransport.

EPA's analysis forrevisions to the EPCRA (SARA Title InI) section 302list indicates that blastwaves causedby the detonation ofcommercial 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 amass explosion hazard, are less likelyto cause a catastrophic event when compared to the same quantity ofhigh explosives. The deflagration orburning ofa low explosive generates lower pressures and is less destructive than the detonation of

a high explosives, although the Agency recognizes that it maybe possible for jome low explosives to detonate under

nusual conditions, with effects similar to the detonation ofa high explosive. Another key distinction between categories ofexplosives is the likelihood ofinitiation of an explosion. Blasting agents, for example, have a mass explosion hazard, but it is much more difficult to set offan explosion ofa 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 andhigh explosives may not be apparent; effects onthe community could be felt from explosions ofboth types ofexplosives.

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

arelationship between the presence or absence ofaccident prevention

measures atfacilities where significant accidental releases of explosives have occurred and the probability that human

or environmental impacts will occur. Nevertheless, historical data demonstrate that explosives can be involved in accidents withthe potential for devastating impacts to the community. The Agencybelieves 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 ofaccident prevention

measures atfacilities where accidental releases ofthese substances have occurred and the probability that human and environmental impacts will occur. EPA also invites comments on methods to evaluate substances onthe basis of these effects and on the ranking ofthese substances. EPA also seeks comments

on which type ofdata (i.e., relationship between accidental releases and human and environmental impacts, accident history, physical/chemical properties)

orcombination ofdata could be used to evaluate the magnitude ofhuman exposure forexplosives.
4. Reactivity

In its analysis forEPCRA (SARA Title Inl) section 302 list revisions, EPA is currently working to identify approaches for evaluating the hazards associated with othertypes of substances that may have explosive properties, e.g., unstable substances such as certain peroxides. To evaluate the hazards ofthese substances, a numberoffactors mustbe considered, such as the energy ofreaction and whether a probable or possible result of the decomposition ofsuch 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 airor water; identifying

common characteristics or specific properties that cause chemicals tobe so reactive with airor water asto pose a hazard to the community requires additional study. Forexample, chemicals that arereactive 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 ofthese reactions would be very different. At present, EPA is attempting to evaluate the hazards ofreactive chemicals and to develop an adequate technical basisto determine the potential effects onthe community. EPA is investigating, for example, computer models that estimate heatsofreaction, and the possible use ofthe heats ofreaction to compare the 5108

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effects ofan explosion of an unstable substance to the effects ofan explosion oftrinitrotoluene (TNT). This methodology would only be appropriate forsubstances that detonate, which appears to be unlikely for many unstable substances. Unstable and reactive substances will be considered for listing foraccidental release prevention ifthe evaluation indicates potential consequences involving the community. Thus, any decision relating to this type ofhazard willbe deferred pending additional Agency review. EPA requests comments on methods that mightbe used to evaluate the potential consequences ofaccidents involving reactive substances.
5.Radioactivity

EPA Is requesting Information to determine the need and appropriateness oflistingradionuclides under this proposed rulerhaking. There are several issuesthat 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 ofsevere health effects in case ofan accidental release? Ifsome jtiionuclides were listed, should they be listed a class ofsubstances, oris it

more appropriate to prioritize their hazards and list specific radionuclides ofconcern? What specific approaches could be taken to develop a methodology that setsthresholds for radionuclides that would represent equivalent hazards tothose posed by other substances listed under this rule? Is the volatility ofradionuclides relevant to their potential tobe released? The Agency is interested in obtaining information on the universe of facilities potentially affected by listing radionuclides; the baseline considered by theAgency is listing ofradionuclides

as a class with levels similar to those established forNRC-licensed facilities under NUREG 1140, A Regulatory Analysis onEmergency 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 inplace for the accidental release prevention ofradionuclides at the Federal, state, or local levels would interact with the accident prevention requirements applicable to these substances. D. ListofSubstances
1.Proposed List

EPA is proposing a list of100 toxic chemicals based on the criteria discussed above and the list of chemicals mandated forinclusion. EPA is also proposing a list of62 flammable gases andvolatile flammable liquids. The listsoftoxic and flammable chemicals are setforth in §67.130 ofthe proposed rule. EPA is also proposing the commercial explosives inDivision 1.1 (explosives with a mass explosion hazard), as defined by DOT; individual commercial explosives are not included

on the proposed list. Inproposing this list, EPA considered the factors specified in the Act: severity ofacute adversehealth effects associated with accidental releases, the likelihood of accidental releases, and the potential magnitude ofhuman exposure to accidental releases (albeitnot directly as function offactors such as population exposed). As noted above, each hazard

was evaluated independently. The final list adopted by the Agency may consist ofacombination ofany ofthese substances. Substances will be placed

on the final listaccording the statutory criteria andbased upon public comment and additional information provided by the public or developed by the Agency

as a result ofpublic comment.

a. ToxicSubstances.All ofthe 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 ofchemicals:

* Gaseson theEHS list.The list includes 22 gases that meet the toxicity criteria based on theirpresence on the EHS list and meet the criteria for likelihood ofaccidental 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 b statute.

* Liquidson theEHS list with vapor pressureof0.5mm Hgorgreater. There

are 65 liquids that meet the toxicity criteria by virtue of Inclusion on the EHS listand meet the criteria for likelihood ofaccidental releasesbecause their vaporpressure under ambient conditions is 0.5 mm Hg orhigher, 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 forlisting 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 notbelieve it is appropriate to include methyl vinyl ketone and methacryloyl chloride on this proposed listbased on toxicity data that may be questionable. * Otherliquidson theEHS list. Toluene 2,4-diisocyanate (584-84-9) and toluene 2,6-diisocyanate (91-08-7)

are included onthe 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 ofaccidents 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 theyhave ambient vapor pressures lessthan 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 riskto human health and the environment from accidental releases.

Releases to air arereported for all of these substances in EPA'sAHE database, even though theirvapor pressure is less than 0.5 mm Hg. Sulfuric acid is one ofthe 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 ofIncidents involving sulfuric acid, more than half ofthem involving releases to air and 60 ofthem involving deaths or injuries. Air releases were reported in more than halfofthe incidents with deaths or injuries, including four where explosions were reported. The ARIP database Includes nearly 150 reports forsulfuric acid. Migration ofsulfuric acid beyond the facility boundaries was reported in a significant number (32) ofincidents. In 5109

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two ofthese cases, migration of sulfuric acid as a vapor or gas was reported.

For phenol, the AHE database includes reports of24 incidents, with one-third ofthem involving releases to air. Deaths or injuries were reported in five phenol incidents, with air releases reported in two ofthem. The ARIP database includes 10 reports for phenol, with migration beyond the fenceline reported in four ofthem. Intwo ofthese
cases, migration beyond the fenceline

was reported forphenol vapor.

Parathion incidents were reported 11 times in the AHE database, with releases to air reported in most ofthem, and deaths or injuries reported in eight of them. Recent regulations have restricted the useofparathion; as a result ofthe restrictions, the likelihood of accidents involving parathion may decrease. EPA requests comments on whether parathion should be included on the list ofregulated 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 ofdeaths 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 listbut are mandated for listing. Both ofthese chemicals have ahistory ofaccidents involving death orinjury. Both ofthese 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 forlisting by OSHA, and

are included because oftheir 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 forduration of exposure. EPAconcluded that listing is appropriate, based on available data.

Congress mandated the listing ofboth 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 withtotal ammonia concentration in water of20 percent by weight orgreater). The concentration cut-offwas chosen so that commonly used commercial solutions of ammonia would be covered.

Congress also mandated the listing of toluene diisocyanate, without specifying

an isomer; EPA is proposing to list toluene diisocyanate (unspecified isomer)(26471-62-5), which is not on theEHS list, in addition to toluene 2,4- diisocyanate (584-84-9) and toluene 2,6-diisocyanate (91-08-7), which are EHSs. The TSCA Inventory includes these three listings for toluene diisocyanate (and noother listings). Including unspecified isomers onthe list should help to ensure that all forms oftoluene diisocyanate are covered, in conformance with the intent of Congress.

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-offof 25 percent is intended to cover commonly-used commercial solutions ofhydrochloric acid; solutions of hydrochloric acid in these concentrations could release hydrogen chloride gas in the event ofa spill. Listing ofthe solution is proposed on the basis ofits potential to release hydrogen chloride, high volume use, and accident history. Hydrochloric acid is one ofthe most frequently reported chemicals in death and injury events and in all events in the AHE database; the ARIP database also includes many reports ofincidents involving hydrochloric acid.

b. FlammableSubstances.The proposed list of62 flammable substances includes 43 flammable gases and 19 volatile flammable liquids that meet the criteria forNFPA's highest flammability hazard- ranking. These substances were identified from NFPA's Properties ofFlammable Liquids, Gases and Volatile Solids and DOT's Hazardous Materials Table; in addition, there wasevidence ofproduction of these substances in commercial quantities. EPA is not proposing to

cover any ofthese substances when they

are used solely for facility consumption

as fuel. Two additional chemicals that met the criteria for listing were excluded from the listbecause they are covered under title VI ofthe Act as amended. Some ofthe substances listed

on thebasis oftoxicity also.meet the flammability criteria; they are listed as toxic substances, however, and were not considered for listing asflammables.

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, orcould be non-explosive, depending on various factors; e.g., particle size, concentration, and other components ofthe formulation. EPA is not proposing to list
any individual explosive substances.

d. Toxic SubstancesNotProposed 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 asEHSs on the 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 notproposed for listing today because of the questionable nature ofthe toxicity. data. Two additional substances on the EHS list that did not meet the vapor pressure criterion were considered for listing because they have been involved 0 in a number ofaccidents with death or injury. These substances, chlordane (57-74-9) and tetraethyllead (78-00-2),

are notproposed 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 ofthese chemicals from the proposed list of substances.

2. Other List Options

As discussed above, the Agency is proposing a list ofsubstances comprised ofthree distinct categories: toxics, flammables, and explosives. The substances listed under each category conform to the discussed criteria forthe particular hazard it presents, and reflect

a measure oflikelihood ofoff-site impacts in case of accidental release. Because these categories have been developed independently ofeach other, the Agency may choose, at the 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.

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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 forthe list ofregulated substances that would meet the statutory criteria. Thisoption is discussed below. The Agency requests comments on anyvariation ofthe proposed list, aswell ason the additional option forcomment.

Entire EHSList.EPA considered the option ofadopting the entire list of360 chemicals regulated under EPCRA (SARATitle II) section 302 asthe list oftoxic chemicals. These chemicals are listed on the basis ofacute toxicity, and, therefore, meet the criterion ofseverity ofacute health effects. Since this list

was adopted in 1986, toxicity data for many of thechemicals 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, theEHS list is based solely upon acute toxicity formost ofthe substances, without any consideration oftheir 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 ofsubstances for accidental release prevention, EPA proposes to focus on those toxic chemicals posing the greatest potential threat to the community from airborne releases. In this way,the initial list willreflect the statutory criteria oflikelihood and magnitude ofrelease. The EHS list includes anumber ofsolids and nonvolatile liquids that, although they meet the toxicity criteria, are expected tobe much less likely to have an effect beyond the fenceline in the event ofan accidental release than those EHSs that

are gases and volatile liquids.
E. ThresholdQuantities

Under CAA section 112(r)(5), EPA must establish threshold quantities for each substance atthe time oflisting. The threshold quantity should take into account the toxicity, reactivity, volatility, dispersibility, combustibility,

orflammability ofthe substance, and the amount ofthe substance known or anticipated to cause death, injury, or serious adverse human health effects. Substances used by farmers as agricultural nutrients may be assigned greaterthreshold quantities or exempted. Two issuesrelated to threshold quantities were considered: Development ofan appropriate threshold quantity fortriggering the risk management prevention regulations and development ofa method for determining whether a stationary source has present a quantity ofa listed chemical greater than the threshold quantity. The Agency does notconsider any thresholds to bea 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 ofthe chemical may pose very different threats depending on the location ofa facility, weather atthe time ofthe release, the elevation ofthe

source ofthe release (e.g., a release from

a smokestack versus a ground level release), and the pressure and temperature ofthe substance, among other factors.
1.Review ofThreshold Methodologies

In developing threshold quantities, the reporting thresholds associated with the other lists considered and the methods used to develop them were reviewed. This review is discussed below.

DelawareMethodology.The Delaware thresholds for toxic chemicals were determined on the basis of dispersion modeling and acombination oftoxicity and vapor pressure; the Delaware "Sufficient Quantity" (SQ) for a toxic chemical is defined asthe quantity that -wouldcreate a potentially lethal concentration atthe facility boundary if released over a period ofone hour.The thresholds are calculated based on an assumption ofa 100-meter distance to the fenceline. Ifthe distance at a facility is greater, the threshold is adjusted upward.

For flammable materials, Delaware provides a calculation method for determination ofthe SQbased on a comparison with propane. The Delaware calculation is based on the release rate calculated forpropane as sufficient to cause death or permanent disability from heat radiation resulting from a fireball at a distance of100
meters fromthe point ofrelease. SQs for other flammable substances are calculated based on the properties ofthe substances compared to the properties ofpropane. Thresholds can be adjusted upward forfenceline distances greater than 100 meters, as fortoxics.

Delaware specifically excludes commercial explosives from its list.For potentially explosive chemicals that are notcommercial explosives, SQs are determined by relating explosion energy fora given mass ofmaterial to an equivalent mass ofTNT. The scaling law, which relates blast overpressure, distance, and mass ofTNT, was used to calculate SQs. The SQ fora reactive substance was the quantity calculated to create an overpressure of 2.3 pounds per square inch (psi)at a distance of 100 meters.

NewJerseyMethodology.New Jersey thresholds fortoxic chemicals are set based on dispersion modeling and mortality curves; a Registration Quantity (RQ) is the quantity that will produce

one fatality in a location with 10,000 people per square mile. NewJersey does not currently list flammable or explosive substances.

ORCMethodology.The methodology recommended by the Organization Resources Counselors (ORC) for the development ofthreshold quantities for toxic cnemicals, presented by aRCto OSHA in public hearings, was also reviewed. This methoduses dispersion modeling, assuming the total quantity of the substance released immediately becomes airborne, to determine the quantity ofa toxic substance that 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, the threshold methodology recommended by ORCwas the same as that used by Delaware to develop SQs forexplosive chemicals, described above.

EHS TPOMethodology.The threshold planning quantities (TPQs) developed for EHSs arebased on aranking ofthe EHSs according to their potential to become airboiine, dispersion potential, 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 ofOccupational Safety and Health (NIOSH), or an approximation of the IDLH based on animal toxicity data,

was used as an index oftoxicity. Physical state and volatility wereused to derive an index ofthe chemical's potential tobecome airborne and disperse. The two indices were combined toproduce an overall risk "ranking factor" defined as IDLH/V, where V isthe index ofpotential to become airborne and disperse. TPQs

were assigned to groups ofEHSs according to theirrelative ranking.

The index ofpotential tobecome airborne and disperse (V)was derived based on physical state and volatility. For EHSs that are gases under ambient conditions, V was assumed tohave a value of 1,indicating that in an accidental release, the total quantity ot chemical involved inthe release could become airborne. For liquids, Vwas calculated by estimatingthe rate of volatilization from a pool (assumed to 5111

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be one centimeter in depth) on a flat, non-absorbing surface using equations presented inAttachment I ofthe Interim Final Rule ofNovember 17, 1986, listing EHSs under EPCRA (SARA Title 11) section 302 (51FR 41580). LiquidsWere assumed to be attheir boiling point, and allliquids were assumed to have the same density as water. A mass transfer coefficient was estimated by reference to water. Because ofthese assumptions, the only variables used in the calculation ofV were the molecular weight andboiling point of the liquid,

The EHSs were ranked according to the ranking factor IDLH/V and assigned TPQs of1, 10, 100, 500, 1,000, or 10,000 pounds based on order ofmagnitude ranges in the ranking factor. The TPQs assigned based on the ranking factors

were reviewed, andchanges were made based on other toxicity data,rapid absorption, chemical reactivity, and consideration ofspecific handling, formulation, anduse information.
2. ProposedThreshold Methodology

RelativeRanking forToxic Chemicals. To set thresholds fortoxic chemicals, EPA is proposing to use a ranking method similar to that used in developing the TPQs for EHSs, as described above, modified to reflectthe different purposes ofthresholds under thisrulemaking; i.e., under EPCRA (SARA Title III) section 302, thresholds onlytrigger reporting by facilities to state and local planners, while under CAA section 112, facilitieswith listed substances in quantities exceeding the threshold willbe required tocomply with prevention requirements, such as the development ofrisk management plans. Usingthe revisedthreshold methodology, aranking factorbased on toxicity and potential tobecome airborne and disperse was derived as described above. In some cases,revised toxicity data orIDLH values wereused. 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 of500 pounds, representative ofdrum-size containers, and, at the maximum level of 10.000 pounds, consistent withreporting requirements already in place for EPCRA (SARA Title IM) under sections 311-312 and 302. UnderEPCRA (SARA Title III) sections 311-312, facilities must submit material safety data sheets, chemical lists, orinventory reportson hazardous chemicals to state and local agencies ata threshold for most chemicals of 10,000pounds. Under EPCRA (SARA Title MI)section 302, the maximum TPQ for EHSs is 10,000 pounds; the presence ofa TPQ ofan EHS requires facilities to notify state and local planners.

A relative rankingmethod to assign thresholds has advantages over developing substance-specific thresholds based on dispersion modeling because airborne dispersion modeling involves many site-specific and accident-specific parameters, including the 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 ofthe release. The Agency's analysis showed that assumptions made for modeling cause wide variations in the results. In addition, therelative ranking takes into accountboth toxicity and volatility. Air dispersion modeling alone does nottake into account the potential for a substance to become airborne. This relative ranking method also is consistent with the methodology for assigning TPQs under EPCRA (SARA Title Ill) section 302.

This methodology has been applied to develop thresholds for additional substances that would be listed ifEPA chose the option, discussed above, of adopting the entire list of EHSs regulated under EPCRA (SARA Title M) section 302. Refer to the technical background documents in the docket for

more information on thresholds for EHSsnot proposed for listing. Thresholds have been developed using this methodology for the four toxic chemicals discussed previously, that appeared to meet the listing criteria but have notbeen proposed for listing because ofquestionable 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; tetraethyllead (78-00-2), 1,000 pounds.

ThresholdMethodology for Flammable Substances.EPA's analysis ofthe hazards of flammable chemicals indicates thatthe greatest hazard to the public from these substances is from vapor cloud explosions. Historical data indicate thatvapor cloud explosions are unlikely for vapor clouds containing quantities less than 10,000 pounds. The quantity in a vapor cloud resultingfrom

an accidental release ofa flammable gas

or volatile flammable liquid could vary greatly depending on site-specific and accident-specific conditions, aswell as properties ofthe chemical released. Because it would be difficult to set chemical-specific thresholds based on all these factors, EPA isproposing to set the thresholds for all the listed flammable substances at 10,000 pounds. EPA believes that this threshold is conservative and protective ofthe public because thevapor cloud resulting from arelease of10,000 pounds would probably contain a quantity less than 10,000 pounds, even though all ofthe listed flammable substances are gases or volatile liquids. Establishing one threshold for allthe flammable substances onthe list also simplifies the regulatory process.

Threshold Methodology for Explosives.EPA's analysis ofexplosives indicates that a blastwave overpressure of3.0 psi from a detonation could have potentially lethal effects in the community beyond the fenceline ofa 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 the scaling law of distances, which relates quantity ofexplosive material and distance fora given overpressure, to estimate the quantity ofhigh explosives that would produce an overpressure of3.0 psi ata distance of 100 meters in the event of

a detonation. Based on thiscalculation, EPA decided to set the threshold for high explosives at 5,000 pounds. Although individual highexplosives may vary intheir explosive power, the variations are not very great; high explosives function by detonation and produce similarresults for agiven weight. EPA believes, therefore, that 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 forhigh explosives; BATF uses one table of distances forall high explosives. EPA believes that this threshold will apply primarily to manufacturers ofhigh explosives, who have larger quantities available on site with the potential for catastrophic releases. Users of explosives (e.g., forindustrial uses, construction, ormining) would probably not have enough high explosives present at onetime tomeet this threshold; lower quantities on site and existing regulations would reduce the likelihood ofcatastrophic events at these facilities.
3. Other Threshold Options

The Agency's proposed options for the threshold quantity methodology relate to the physical/chemical properties ofthe substances and the specific hazard that each substance I 5112

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presents (i.e., toxicity, flammability, explosivity). EPA recognizes however, that the impact of arelease in a particular instance may be greater or lesser depending upon site-specific considerations and that there may be other factorsthat 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 ifit is typically handled at elevated temperatures and pressures. Other factors that 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 partitular chemical (e.g., a chemical may be typically used at
remote locations, far from dense population centers or sensitive ecosystems), orprocess type in which a chemical is typically involved. The advantages ofthis approach wouldbe that it would more specifically tailor threshold quantities based on common

use patterns ofa substance. The disadvantage would be that this approach would not apply to ubiquitous chemicals that are used in a wide variety ofapplications, 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 ofa 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 ofthe aforementioned factors (or other factors)
to establish threshold quantities.

In developing the proposed threshold methodologies, the Agency also considered four additional options, which are discussed below. Three of these methodologies are based on intrinsic properties ofeach 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. VaporQuantityMethod(Toxics).EPA considered a method similar to that recommended by ORC fordevelopment ofthreshold 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 of100 meters from the source ofthe 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 forHazards Analysis (EPA, FEMA, and DOT, 1987). For the calculations, moderate conditions ofa wind speed of10 miles per hour (4.4 meters per second), atmospheric stabilityD, and urban conditions were assumed. The duration ofthe 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 ofassigning thresholds

assumes that the total quantity ofthe substance becomes airborne. It does not consider the chemical properties that might affect the likelihood ofan accidental release. The volatility ofthe listed chemicals is not taken into account; e.g., a gas could be assigned the

same threshold as a liquid with relatively low volatility ifthe 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 ofchemical-specific calculations such

as those used under this method may have little relation to what might happen during an actual release.

TPQMethod(Toxics). EPA also considered using the TPQs under EPCRA (SARA Title Ill) section 302 as the thresholds for toxic substances under this rulemaking. However, the purpose ofthe TPQs is to trigger reporting by the facility to state and local emergency planners ofthe presence ofan EHS. The community planners then carry out an analysis of the hazardsposed by the substance and

use this analysis to set priorities for community planning. The primary purpose ofthe threshold quantities under thisrule, however, is to trigger mandatory prevention requirements to prevent the catastrophic accidental release ofa regulated substance. Therefore, thresholds under this rule should represent quantities that are sufficiently hazardous (i.e., pose arisk ofcatastrophic event) to merit the requirement fora riskmanagement plan

on a site-specific basis.These quantities shouldbe higher than the TPQs. which only represent a level where the hazard should be considered forplanning 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 of5,000 pounds. A TPQ of 10,000 pounds generally corresponds to a threshold of10,000 pounds.

Alternative Overpressure Levels (Explosives).EPA considered basing the threshold quantity for explosives on other overpressure levels; for example,

an overpressure of2.0 psi, a level which could cause the partial collapse ofwalls and roofs ofhouses, 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 ofan accidental release. Adopting OSHA's Thresholds

For chemicals listed under both OSHA's chemical process safety standard and the list ofregulated 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 ofOSHA-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 5113

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ofthe public outside the workplace or offsite.

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 toOSHA'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) (7647-01-01, 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 ofregulated 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 ofthe worker may differ from levels that

are protective ofthe public. EPA believes it is reasonable for the EPA thresholds generally tobe 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 theworkplace 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 that the scientific methodology applied to determine the protective thresholds for these 15 chemicals should be consistent with that used for the remaining substances

on the EPA list.By adopting a consistent methodology, EPA can

ensure that there is areasonable relationship between the thresholds for substances on EPA's list that are on OSHA's list and those that are not, and between substances listed in the initial rulemaking and those added subsequently by petition orother 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 oftoxics, flammables and explosives and their corresponding offsite effects willbe 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 ofPresence of Threshold Quantity

The purpose ofthe threshold determination is to evaluate (a) whether

a facility is covered for a specific regulated substance and Mb) whether a particular location within the facility is subject to regulations based on the presence ofthe substance. In deciding how the presence of athreshold 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 ofEPCRA (SARATitle I1), a facility is covered ifthe total quantity ofan EHS present on site at any one time is in

excess ofits TPQ.New Jersey's threshold also is applied to the maximum quantity on site at anytime. Under Delaware's approach, facilities must determine the maximum quantity ofa toxic chemical that could be released at one time,using guidance provided by the state to account for. facility-specific factors. Ifthis potential release quantity is greater than the threshold, the facility is covered by the Delaware RMP regulations. OSHA proposed thatthe threshold quantity be based on the amountused 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 ofthese activities." Vessels that are interconnected or vessels thatare not interconnected but could be involved in

a potential release are considered a single process.

EPA is proposing to apply the threshold quantity tothe maximum total quantity ofa 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, orin several vessels that could be involved at onetime 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 systemby pipes, pumps, or otherconveyance 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 ofa substance that could be released in a single accident. For example, ifa facility uses 300 pounds of chlorine in one process, uses 150 pounds totreat wastewater, and stores 600 pounds, the facility would have a total of 1,050 poundsquantity on site. The proposed threshold quantity for chlorine is 1,000 pounds. gall ofthe chlorine is kept andused i1 a single
area, where a fire or explosion could affect the chlorine cylinders, morethan 1,000 pounds have the potential of being released in a single incident, thereby exceeding the 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. EPAalso believes that considering only the quantity in

one vessel or interconnected vessels would notbe sufficiently protective in

some cases. For example, debris from an explosion could puncture a nearby container, or a fire could cause a number ofcontainers or pipes to rupture.Therefore, EPA is also proposing that threshold determination consider all vessels located sufficiently close to each other that they might be involved in arelease at onetime. EPA believes this approach is relatively simple to implement and verify and also reasonably approximates the potential release quantity.The Agency recognizes, however, that thismethod 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 ofcombinations of substances. EPA requests comments on theproposed approach. 5114

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EPA considered applying the threshold quantity to the total quantity

on site at a facility, as under EPCRA (SARATitle III) section 302. A facility wouldbe covered ifit hadpresent an amount of a listed substance exceeding its threshold quantity regardless ofits location or distribution on the site. This method is clear andunambiguous; no complicated formulas or definitions need tobe 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 tobe an overly conservative approach.

Another approach considered was to base determination ofthethreshold on the maximum quantity ofthe regulated substance capable ofbeing released in a worst-case accidental release. This approach is used by Delaware fortoxic chemicals. Under the Delaware regulation, the facilities must calculate

a worst-case potential release quantity based on formulas provided. Some difficulties havebeen reported with this approach; forexample, the calculations require a technical knowledge not available atthe full range ofpotentially covered facilities. Again, EPA believes this approach may present enforcement and compliance problems dueto the lack ofeasily verifiable criteria. EPA requests comments onthe proposed definition for threshold quantities and the alternative approaches considered as options.
5.Threshold Exemptions

EPA is proposing several exemptions to limitthe quantities ofsubstances included inthe threshold determination. EPA would adopt the exemption applied under EPCRA (SARA Title IM) which does not consider substances in mixtures ifthey represent less than one percent ofthe mixture by weight Regulated substances in such dilute solutions are unlikely to pose a hazard to the community in the event of an accidental release. In addition, it might notbe feasible in many casesfor facilities to calculate small quantities ofsubstances that may be contained in mixtures.

EPA also is proposing to exempt substances contained in "articles" from the threshold determination. The OSHA definition ofan 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 forthe following purposes from Inclusion in the threshold determination: substances that are a structural component ofthe facility; substances used for routine janitorial maintenance; substances in

consumer products; and substances in water drawn from the environment or municipal sources. EPA also would exempt activities in laboratories when under the supervision ofa technically qualified person. EPA considers it less likely that substances stored in these exempt forms could be involved in accidental releases ofacatastrophic nature.

These proposed exemptions parallel the exemptions provided under EPCRA (SARA TitleIII) sections 311 and 312 for threshold calculations. EPA recognizes that under EPCRA (SARATitle III) section 302, there are no similar exemptions from threshold determination. However, asnoted previously, EPCRA (SARA Title 11) section 302 does notrequire facilityspecific prevention measures, in contrast to the requirements ofCAA section 112(r). EPAbelieves these exemptions are necessary to avoid covering facilities whose use ofthe substances does notmerit 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, orin specific supervised situations. For example, without the article exemption, car dealers and service stations could'be covered because ofthe acid in car batteries. Under EPCRA (SARA Title MI) section 302, facility notification to local and state emergencyplanners may be appropriate in order for them to consider the risk to the community, but mandatory prevention requirements in all cases would be excessive.

In addition, EPA is proposing to exempt listed flammable substances used solely for facility consumption as fuel. This exemption isconsistent 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 ifthey are in concentrations by weight above specified levels; for example, hydrochloric acid would be covered only when it is in solution at a concentration of25 percent orgreater, aqueous solutions of ammonia must be considered only ifthe concentration is 20 percent or greater, and hydrogen peroxide solutions must beconsidered ifthe concentration is greaterthan 52 percent. Stationary sources would not be required toestimate quantities of more dilute solutions ofthese substances. These concentrations represent typical industry handling of these mixtures. For mixtures or solutions ofother listed substances, determination ofwhether a threshold quantity is present would be based on the quantity ofthe listed substance in the mixture or solution. Forexample, fora 25 percent solution ofa listed substance with athreshold quantity of 500 pounds, more than 2,000 pounds of the solution wouldbe needed to exceed the threshold for the listed substance.

IV. OtherIssues
A. StatePrograms

The Act encourages statesto develop programs to implement CAA statute requirements. EPA willbe publishing guidance to assist inthe development of state programs and inthe implementation ofsection 112(r) requirements. Section 112(l)(1) indicates that statis may submit State Program Plans outlining the implementation and enforcement ofsection 112(r) requirements. The chemical list and reporting thresholds EPA adopts will provide a minimum set ofrequirements 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 NewJersey already have chemical accident prevention regulations that require facilities to develop and implement risk management plans. Foreach ofthese 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 TitleIll) section 302;that is, the California program covers all 360 extremely hazardous substances on the EPCRA (SARA Title III) section 302 list at their TPQs. New Jersey has developed its own list ofchemicals and thresholds. Delaware has alsodeveloped a separate list; Delaware's thresholds are dependent onboth the quantity ofthe substance on site andthe distance to the nearest population. Ifan established state program does not include allthe substances at the threshold quantity set by EPA (orat a lower, more stringent threshold), the program would have to be revised tobring itinto compliance with the Federal requirements when they are promulgated. 5115

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B. OSHA'sListof Highly Hazardous Chemicals

In developing the proposed list of substances and thresholds, EPA considered the possibility ofadopting the list ofhighly hazardous chemicals and thresholds OSHA lists for its chemical process safety standard. EPA conducted its analysisbased on the proposed OSHA standard available at the time,with coordination withOSHA between theirproposal and final versions. However, OSHA's list does not include allthe substances mandated for listing by Congress. It does not include allEHSs that meet EPA's proposed criteria and includes several substances that EPA cannot listunder the Act. It also includes a number ofsubstances that are not in commercial production. EPA is required to consider likelihood ofa release; substances that are notin commercial production would be unlikely tobe 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 ofreactive chemicals. EPA is currently considering whether reactive chemicals pose a potential threat to the public health or welfare (asopposed to worker safety), and is deferring listing such substances for the accidental release provisions pending further analysis oftheir 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 liststo the 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 oftoxic substances and 11 on the list of flammable substances). Of the substances that are listed by both OSHA and EPA, 10 (9toxics and I 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 toprotect the community, it is reasonable that EPA's thresholds should be higher. However, OSHA's thresholds are higher for 15 substances.
C.RelationshiptoEPCRA (SARA Title III)Section302/303

Under EPCRA (SARA Title III) section 302, EPA published alist ofextremely hazardous substances (EHSs) and threshold planning quantities (TPQs). Facilities with EHSs, in quantities exceeding the TPQmust notify the State Emergency Response Commission and Local Emergency Planning Committees. Identification offacilities with EHSs above their TPQs Is intended to.provide local emergency planners with abasis for further analysis ofthe potential danger posedby these facilities. The TPQs do nottrigger any specific requirements, other than notification and designation ofa facility coordinator, for facilities with EHSs, nor dothey trigger any specific emergency planning requirements atthe facilityother 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 ofhazards that has resulted from EPCRA (SARATitle III) section 303 activities. The main distinction between EPCRA (SARA Title III) section 303 requirements and the CAA requirements isthat 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 ofsubstances and threshold quantities being proposed under CAA section 112(r) triggers mandatory prevention requirements by facilities for prevention ofaccidental releases. EPA, therefore, believes it is appropriate that the list oftoxic chemicals under CAA section 112(r) shouldbe limited to gases and volatile liquids with evidence ofproduction, unlike the EHS list, which is based only

on toxicity, and that the thresholds for toxic chemicals under CAA section 112(r) should behigher than the TPQs under EPCRA (SARATitle I) section 302. In addition, determination ofthe presence ofaTPQ ofan EHS under EPCRA (SARATitle III) section 302is based on the total quantity ofthe EHS
atthe facility, while under CAA section 112(r), the proposed method of threshold determination isbased on the quantity ofthe regulated substance in a process. EPAbelieves it is appropriate under EPCRA (SARATitle I) section 302 to identify facilities based on the total quantity on site; emergency planners can then take factors such as location and distribution ofvessels into
account when setting priorities for planning. On the other hand,EPA believes it is more appropriate under CAA section 112(r), because of the 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 Ill) section 302, following completion ofits analysis ofthe hazards ofsuch chemicals. Because of the different purposes ofEPCRA (SARA TitleIII) section 302 and CAA section 112(r), it may be appropriate tohave somewhat different lists and thresholds under EPCRA (SARA Title I) section 302. For example, toprovide local emergency planners with sufficient Information to allow them to set planning priorities fortheir communities, EPA mayuse less stringent criteria forlisting (e.g., blasting agents as well ashigh 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 NutrientExemption 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 onthe proposed list ofsubstances that would be used as an agricultural nutrient and thus couldbe subject to the higher threshold orexemption. EPA is proposingto exempt ammonia fromthe requirements ofthisrulewhen held by

a farmer as an agricultural nutrient. EPA is proposing this exclusion for two

reasons. First,the farmsthatuse ammonia asa fertilizer areprimarily growing corn, wheat, and cotton, and involve large acreages and the ammonia isintentionally released to the environment. Second, many elements of chemical accident prevention programs may.notbe directly relevant to the use ofammonia as a fertilizer. EPA requests comments on the proposed exemption. EPA notes that farm contractors who sell ammonia as a fertilizer would be coveredby today's proposed rule.
E.InformationGathering Efforts Before EPA began writing its proposed rules foraccidental release prevention, the Agency decided to seek information from those already implementing similar regulations. EPA staffmet extensively with officials in three states and held interviews with

seven facilities that have developed RMPs under state laws. To gather more information, EPA held eight focus groups, five with facilities (twoeach in New Jersey and California, one in Delaware), and three with administering agency officials in California, to elicit their opinions on the regulations and theirideas about the most useful 5116

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program components. After analyzing the results ofthese meetings, EPA held

a two-day seminar on issues that have arisen at the state level. Officials from California, Delaware. andNew Jersey, as well as Minnesota, Texas,New York, and Wisconsin, attended the meetings. On the second day, other groupsthat 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, the OSHA, EPA, and state chemical lists andrelated regulations should be consistent. Several facilities indicated that they would like the regulations arranged so that ifthey are in compliance with one rule, theywould be in compliance with all rules, at least fora specific chemical. Itwas noted that the chemical list should bebased 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 thisinformation gathering effort entitled CleanAirAct of1990, Chemical AccidentReleaseProvisions, Reporton FocusGroupsandRound Table Discussions, transcripts ofthe focus group sessions, and a report on thetwoday seminar are available in the docket.

V. Petitions for Additions and Deletions
A.InformationRequired from Petitioner
The Actrequires EPA toreview the list at least every five years; EPA may revise the list eitherthrough petitions or by Agency initiative. EPA is required to develop procedures for the addition and deletion ofsubstances 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 ofregulated substances foraccidental release prevention within 18months of submission ofthe petition. For EPA to complete its review of petitions and publish the results ofits 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 ifthe petitioner presents the information in the order listed below.

* Name andaddressofthepetitioner andabrief descriptionofthe organization(s) thatthepetitioner represents,ifapplicable.

* Name,address,andtelephone numberofacontact person forthe petition. o Common chemicalname(s),

common synonym(s), Chemical AbstractsService(GAS) number,and chemical formula andstructure.The CAS numberis aunique number assigned to chemical substances by the American Chemical SocietyChemical Abstracts Service Registry System. The CAS numbers are independent of nomenclature and have nochemical significance. They are assigned aseach

new chemical enters the CAS Registry System.

9Action requested. The petitioner
must identify whether the request is to add to or delete from the list of reulated substances for accidental release prevention.

• Rationalesupportingthe petitioner's position.Each petition must present a discussion ofthe rationale to add or delete each substance based upon the data presented and their relationship to the criteria for addition

ordeletion. A short summary ofthe rationale must be submitted along with

a more detailed narrative that includes

a discussion ofthe available data on the potential for acute adversehuman health effects that occur as a result of exposure to the substance. Physical and chemical data related to the likelihood ofaccidental releases and the magnitude ofhuman 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 ifthey meet the mammalian toxicity criteria for listing asEHSs (discussed in Section I Cofthis 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 chemicalsthat meet the toxicity criteria will be considered for listing ifthey have a history of involvement in accidents that caused death orinjury. For flammable chemicals, data should indicate that the substances are flammable gases under ambient conditions, or that they are liquids with boiling point below 100OF (37.8 0C)and flash point below 73 OF (22.8 *C). For a petition to delete, data must be submitted demonstrating that the substance would notreasonably be expected to cause death, injury, or serious adverse effects to human health

orthe environment in the event ofan accidental release. Available data on all hazards presented by the chemical should be included. * Supportingdata.The petitioner must provide EPA with sufficient information to support scientifically his

orher request to add to or delete from the list ofregulated substances for accidental release prevention. Duplicate copies ofall material submitted and an English translation ofany Information published in a foreign language should be included with the petition in order to expedite the review process.

All data presented must meet basic criteria foracceptable scientific quality. These include, but are not limited to, appropriate study design, quality ofthe scientific approach/method, appropriate quality assurance and qualitycontrol procedures, and appropriate statistical analyses.

The supporting data for the petition must contain, at a minimum, te following elements:

* Listofsupportingdocuments.The petitioner must include a summary list ofall supporting documents included with the petition.

* Literature searches. The petitioner must include a printed copy ofall literature searches conducted to Identify data available for the substances, including identification ofthe database(s) searched, the search strategy, dates covered, and printed results. The literature searches must havebeen conducted within six months prior to submission ofthe petition.

* Effects data.Each petition must include summary tables identifying all studies cited. Thepetitioner must submit printed copies ofthe studies cited on these tables. The reports of effects data should include all available reports on effects ofshort-term exposure to the chemical and should notbe limited to reports onthe effect for which the chemical was listed. Human studies, animal studies, otherenvironmental 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 beevaluated for adequacy using standard EPA guidance documents andbasic toxicologic principles. EPA will place greater confidence in studies that have been published in peer-reviewed scientific journals orbooks. In addition, the petitioner may be aware ofsupporting studies, data, orreports that were not Eublished in peer-reviewed journals or

ooks. In such cases, the petitioner should submit a printed copy ofeach relevant non-peer-reviewed citation. Examples ofsuch citations may include proceedings ofscientific meetings, studies conducted at an industrial site for internal purposes, and some government-sponsored reports/ assessments.

* Exposure and accident history data. The petition should include data related to the potential for serious adverse

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human health or environmental effects. Relevant physical and chemical properties ofthe substance (e.g., boiling point and vaporpressure) shouldbe included, with literature citations. Air dispersion modeling results may be included. Assumptions and data used for the modeling should be presented clearly, and documentation for the model used shouldbe included in the submission. Historical data on accidents involving the substance may be included, clearly citing the sources of the data.
B. PetitionProcess

The guidance presented in this proposed rulemaking is intended to provide ageneral framework for determining petition adequacy. Because most petitions will have specific issues not covered by this guidance, individuals wishingto petition EPAto modify the list ofregulated substances for accidental release prevention are encouraged to request a pre-petition conference with EPA. Such a meeting would facilitate submittal ofcomplete 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 DC20460. 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 ofparticipants.

A petition to modify the list of regulated substances for accidental release prevention under section 112(r) ofthe 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 apetition, EPA will first review the petition for completeness. Ifthe petition is found to be incomplete, EPA will return it to the petitioner identifying the omissions. The petitioner may correct the deficiencies and resubmit the petition. This action willbe considered equivalent to submitting anew petition; thus, EPA will have 18months to review the petition contents and publish

a decision to grant or deny the petition. Ifthe petition is found to be complete, EPA proposes to publish the following two notices in the Federal Register:

1.Notice ofPetitionReceiptand Request for Comments:This notice will

announce that acomplete petition has been received and will identify the following: the petitioner, the action requested (regulated substance, addition/deletion), the rationale and summary ofthe key data submitted in support ofthe petition, and the listof 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 that was not identified by the petitionerif such information might assist EPAin making the decision to grant or deny the petition. Additional data will be accepted for sixty days following publication ofthis notice. The request for information will constitute arequest forpublic comments on the petition. All pertinent information and comments received will be addressed in the notice granting or denying the petition.

2.Publicationof Decision: This notice will announce EPA's decision to grant

ordeny a specific petition.

EPA anticipates publishing the two notices discussed above within 18 months ofreceiving a complete petition. EPA will not accept additional petitions

on the same substance following publication ofa final notice ofthe decision to grant ordeny apetition unless new data become available that could significantly affect the basis for the decision made byEPA. 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 the petition was submitted and the previous petitioner. Information previously submitted need notbe resubmitted but may be cited by reference for reconsideration. EPArequests comments on the proposed information to be required fromthe petitioner and the proposed petition process.
VI. Discussion oftheProposed Rule

EPA is proposing to add Part 67 to Title 40 ofthe Code ofFederal Regulations, which would include the list ofregulated substances and threshold quantities, as well asthe requirements for the petition process to add regulated substances to the list orto delete regulated substances from the list.

Proposed §68.5 would establish the procedures to determine whether a threshold quantity ofa regulated substance is present ata 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 ofthesubpart as the designation ofregulated substances and theirthreshold quantities, and establishment ofthe requirements for petitions to add substances or delete substances from the list.

Proposed §68.120 would specify the requirements forpetitions to theAgency 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 the list ofregulated substances, including a list oftoxic substances, a list of flammable substances, and a list criterion forcommercial high explosives. This section alsowould establish the threshold quantities forall listed substances.
VII. Required Analyses
A. E.O. 12291

Under Executive Order 12201, 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 orprices to consumers, individual industries, Federal, state, or local government, or geographic region, or

3. Significant adverse effects on competition, employment, investment, productivity, innovation, orthe ability ofU.S.-based enterprises in domestic or export markets.

Based on the 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 perfacility for highly complex manufacturing facilities.

EPA has determined the proposed rule is not a majorrule for the purposes ofE.O. 12291 because the list, by itself, imposes no cost on facilities. The cost impact ofthe list and thresholds derives from compliance withthe risk 5118

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management regulations and other reasonable regulations, which are triggered by the presence ofa regulated substance above its threshold quantity. Because the impact ofthe list and threshold decisions are felt through the risk management regulations, EPA has prepared a combined preliminary RIA entitled, "Regulatory Impact Analysis in Support ofListing Regulated Substances and Thresholds andMandating Risk Management Programs for Chemical Accident Prevention, asRequired by section 112(r) ofthe CAA," which analyzes the impacts ofvarious list and threshold options on the risk management requirements. The RIA is available in the docket.

The petition process is the only aspect ofthisrulemaking that is directly attributed to the listing ofsubstances. EPA estimates that the petition process under this rulemaking will cost a facility submitting apetition an average of$5,000. EPA estimates that there will be 11 petitions a year. EPA anticipates that the cost to the Federal government forprocessing and reviewing the petitions will be approximately equal to the 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. RegulatoryFlexibilityAct

In accordance with the Regulatory Flexibility Act of 1980, Federal agencies must evaluate the effects ofthe rule on small entities and examine alternatives that may reduce these effects. Because the proposed rule, by itself,has no cost impact on facilities, a separate Regulatory Flexibility analysis was not conducted, but isincluded in the combined RIA, available in the docket.
C.Paperwork ReductionAct
The information collection requirements in this proposed rulehave been submitted for approval to the Office ofManagement and Budget (OMB) under the 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 SandyFarmer, Information Policy Branch, EPA, 401 M St. SW. (PM-22Y), Washington, DC 20460, orby calling (202) 260-2740.

Public reporting burden for this collection ofinformation in the petition process, the only aspect ofthe proposed rule involving reporting or recordkeeping, is estimated to be approximately 138hours, including time forreviewing instructions, searching existing data sources, gathering and maintaining data needed, and completing and reviewing the collection ofinformation. 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 theburden estimate or any other aspect ofthis collection ofinformation to Chief, Information PolicyBranch, PM-223Y, U.S. EPA, 401 M St. SW., Washington, DC 20460, and the Office ofInformation and Regulatory Affairs, Office of Management and Budget, Washington, DC20503, Attn: Desk Officer for EPA. The final rule will respond to any OMB

orpublic comments on the information collection requirements contained in this proposal.
List ofSubjects in 40 CFRPart68

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 setout in the preamble, title 40, chapter I,subchapter C ofthe Code ofFederal Regulations is proposed tobe amended by adding a
new part 68 to read as follows: PART68-CHEMICAL ACCIDENT
PREVENTION PROVISIONS SubpartA-General

Sec. 68.1 Scope. 68.3 Definitions. 68.5 Threshold determination. SubpartB-Risk Management Plan Requiremeirts [Reserved] Subpart C-Regulated Substancesfor Accidental Release Prevention 68.100 Purpose. 68.120 Petition process. 68.125 Exemptions. 68.130 Listofsubstances.

Authority: 42 U.S.C. 7412(r). Subpart A-General
568.1 Scope.

This part sets forth requirements for chemical accident prevention steps that must be taken by the owner oroperator of stationary sources. §68.3 Definitions.

For the purposes ofthis part: Accidentalrelease means an unanticipated emission ofa regulated substance or other extremely hazardous substance into the ambient air from a stationary source.

Administrator means the administrator ofthe U.S. Environmental Protection Agency. Articlemeans a manufactured item that is formed to a specific shape or design during manufacture,'that has end

use functions dependent in whole orin part upon the shapeor design during end use, and that does not release or otherwise result in exposure to a regulated substance under normal conditions ofprocessing and use.

CAS means the Chemical Abstracts Service.

Process means any activity involving

aregulated substance including any use, storage, manufacturing, handling, or onsite movement ofsuch substances, or combination ofthese activities.For the purposes ofthis 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, shallbe considered a single process.

Regulatedsubstance is any substance listed under section 112(r)(3) ofthe Clean AirAct as amended, and §68.130.

Stationary sourcemeans any buildings, structures, equipment, installations, orsubstance emitting stationary activities which belong to the

same industrial group, which are located on one or more contiguous properties, which areunder the control ofthe same person (orpersonsunder

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 forthe purposes of temporary storage, loading, or unloading. Thresholdquantitymeans the quantity specified forregulated substances under section 112(r)(5) ofthe Clean AirAct as amended, and listed in §68.130 and determined tobe present at

a stationary source asspecified in §68.5.

Vessel means anyreactor, tank, drum, barrel, cylinder, vat, kettle, boiler,pipe, hose, or other container. §68.5 Threshold determination.

(a) A threshold quantity ofa regulated substance aslisted in S68.130 is present ata stationary source ifthe total quantity ofthe regulated substance contained in a process exceeds the threshold.

(b) For the purposes ofdetermining whether morethan a threshold quantity ofa regulated substance is present at the stationary source, the following exemptions apply:

(1)Concentrations ofa regulated substance in amixture. Ifaregulated substance is present In a mixture and 

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## / Tuesday, January 19, 1993 / Proposed Rules

theconcentration ofthe substance is below one percent by weight ofthe mixture,the amount ofthe substance in the mixture neednot beconsidered when determining whether more than a threshold quantity ispresent at the stationary source.

(2)Alices.Regulated substances contained in articles need notbe considered when determining whether

morethan athreshold quantity is present at the stationary source.

(3) Uses.Regulated substances used forthe following purposes need notbe included when determining whether

more than a threshold quantity is present at the stationary source:

(i)Use asa structural component of the stationary source; (ii)Use ofproducts forroutine janitorial maintenance; (iii) Useby employees offoods, drugs, cosmetics, orother personal items containing the regulated substance;

(iv) Use ofregulated substances present inprocess water ornon-contact coolingwater as drawn from the environment or municipal sources, or
use ofregulated substances present in air used either as compressed air oras part ofcombustion; and

(v)Use solely for consumption as fueL (4)Activities inLaboratories. Ifa regulated substance is manufactured, processed, or used in a laboratory at a stationary source under the supervision ofatechnically qualified individual as defined in §720.3(ee) ofthischapter, the quantity ofthe substance need not be considered in determining whether a threshold quantity is present. This exemption does notapply to:

(i) Specialty chemical production- (ii)Manufacture, processing, or use of substances in pilotplant scale operations; and

(iii)Activities conducted outside the laboratory.
Subpart B--Risk Management Plan Requirements [Reserved) Subpart C-Regulated Substances for
Accidental Release Prevention

168.100 Purpoae.

This subpart designates substancesto be listed under section 112(r) (3), (4), and (5) ofthe Clean AirAct, as amended, identifies theirthreshold quantities, and establishes the requirements forpetitioning to add or delete substances from the list. S68.120 Petition process. (a)Any person may petition the Administrator to modify, by addition or deletion, the list ofregulated substances identified in §68.130. Based on the information presented by the petitioner, the Administrator may grant ordeny a petition.

(b) A substance may be added to the list if,in thecase ofan accidental release, it is known to cause or may be reasonably anticipated to cause death, injury, or serious adverse effects to human health or theenvironment.

(c) A substance may be deleted from the list ifadequate data on the health and environmental effects ofthe substance are available to determine that the substance, in the case ofan accidental release, will not cause death, injury, or serious adverse effects to human health or the environment.

(d) No substance for which anational primary ambient air quality standard has been established shall be added to the list. No substance regulated under titleVI ofthe Clean AirAct, as amended, shall be added to the list.

(e)The burden ofproofis on the petitioner to demonstrate that the criteria for addition and deletion are met. A petition will be denied ifthis demonstration is not made.

(f) The Administrator will not accept additional petitions on the same substance following publication ofa final notice ofthe decision to grant or deny apetition, unless new data become available that could significantly affect the basis forthe decision.

(g) Petitions to modify the list of regulated substances must contain the following:

(1) Name and address ofthe petitioner and abrief description ofthe organization(s) thatthe petitioner represents, if applicable;

(2) Name, address, and telephone number ofa contact person forthe petition;

(3) Common chemical name(s),

common synonym(s), Chemical Abstracts Service number, and chemical formula and structure;

(4) Action requested (add or delete a substance);

(5) Rationale supporting the petitioner's position; that 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; thatis, the petition must include sufficient information to scientifically supportthe request to modify the list. Such information shall include:

(i) A listofall support documents; (ii)Documentation ofliterature searches conducted, including,but not limited to, identification ofthe database(s) searched, the search strategy, dates covered, andprinted results; (ii) 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 orprevious accident history data, indicating the 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 ofthe' substance, such as vapor pressure; modeling results, Including data and assumptions used and model documentation; and historical accident data, citing data sources.
§68.125 Exemptlons.

Agricultural nutrients. Ammonia used

as an agricultural nutrient, whenheld by farmers, need notbe included when determining whether a threshold quantity is present on site.
§68.130 Ustofsubtarce.

(a)Explosives are covered under section 112(r) oftheClean Air Act if they are classified by DOT inDivision 1.1(49 CFRpart 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 andflammable substances under section 112(r) ofthe Clean AirAct are the substances listed inTables 1,2, 3, and4 ofthis section. Threshold quantities for listed toxic and flammable substances are specified in the tables. (c)The basesfor plarcng toxic and flammable substances onthe list of regulated substances are explained in the notes tothelist. 

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TABLE 

### 1TO §68.130.-LIST OF REGULATED Toxic SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEASE PREVENTION (Alphabetical Order-100 Substances)

Chemical name CAS No. Threshold Basisfor quantity (Ibs) listing

Acetone cyanohyddn 5....................................................................................................................................................... 75-86-5 5,000 (b) Acrolen

............................................................................................................................................................................. 107-02-8 1.000 (b) Acrylonitl0e

........................................................................................................................................................................ 107-13-1 10,000 (') Acry ly chloride

................................................................................................................................................................... 814-68-4 1,000 (b) Alyl alcohol

........................................................................................................................................................................ 107-18-6 5,000 (b) Allylamine

........................................................................................................................................................................... 107-1 -9 1,000 () Ammona (anhydrous)

....................................................................................................................................................... 7664-41-7 1,000 b) Ammonia (aqueous solution. conc 20%or greater)

.......................................................................................................... 7664-41-7 5,000 ("b) A llne

................................................................................................................................................................................ 62-53-3 5,000 (b) Antimony pentafluo de

...................................................................................................................................................... 7783-70-2 1,000 (b) Arsenous trilo rIde

........................................................................................................................................................... 7784-34-1 5,000 (b) Arsine

................................................................................................................................................................................. 7784-42-1 500 () Benzal chloide

................................................................................................................................................................. 98-87-3 1.000 (b) Benzenamlne, 3-{tdfluoromethyl)-

..................................................................................................................................... 98-1 -8 1,000 (b) Benzotlichlodde

................................................................................................................................................................. 98-07-7 500 () Benzy d chloride

.................................................................................................................................................................. 100-44-7 1,000 C') Benzyl cyande

.................................................................................................................................................................. 140-29-4 1,000 () Boron trichlodde

................................................................................................................................................................. 10294-34-5 1,000 (b) Boron trfluorde

................................................................................................................................................................. 7637-07-2 1,000 (b) Boron trnfluorlde compound with methyl ether (1:1)

......................................................................................................... 353-42-4 5,000 () Bromi¢ne

.............................................................................................................................................................................. 7726-95-6 1,000 (-. b) Cartondisulfide

................................................................................................................................................................. 75-15-0 10,000 (b) Chlorine

.............................................................................................................................................................................. 7782-50-5 1,000 (, b) Chlorine dio de

................................................................................................................................................................. 10049-04-4 500 (d) Chloroethanol

..................................................................................................................................................................... 107-07-3 1,000 () Chloroform

......................................................................................................................................................................... 67-66--3 10,000 (b) Chlorom thyl. ether

............................................................................................................................................................ 542-88-1 500 (b) Chloromethyl methyl ether

................................................................................................................................................. 107-30-2 1000 (b) Crotonaldehyde

.................................................................................................................................................................. 4170-30-3 10,000 C')
Crotonaldehyde, (E)-

......................................................................................................................................................... . 123-73-9 10,000 (b) Cyanogenchloride

............................................................................................................................................................. 506-77-4 1,000 (d) Cyclohexylamine

............................................................................................................................................................... 108-91- 5,000 (b) Diborane

............................................................................................................................................................................ 19287-45-7 500 (b) Trans-1.4-dchloro.butene

................................................................................................................................................... 110-57-6 1,000 ) Dichloroethyl ether

............................................................................................................................................................. 111-44-4 10,000 (b) Dimethyldichlorosllane

....................................................................................................................................................... 75-78-5 1,000 (b) Dimethylhydrazne

............................................................................................................................................................. 57-14-7 5,000 (b) Dimethyl phosphorochlondothloate

................................................................................................................................... 2524-03-0 1,000 (b) Epchlorohydrin

................................................................................................................................................................. 106-89-8 10,000 C') Ethylenediamine

................................................................................................................................................................ 107-15-3 10,000 (b) Ethyleneim e

.................................................................................................................................................................... 151-56-4 1,000 (,b) Ethylene oxidle

............................. I...................................................................................................................................... 75-21-8 5,000 (,- b) Fluorine

............................................................................................................................................................................. 7782-4 1-4 500 () Formaldehyde

.................................................................................................................................................................... 50-00-0 500 (b) Formaldehyde cyanohydrin

............................................................................................................................................... 107-16-4 5,000 (b) Furan

.................................................................................................................................................................................. 110-00-9 1,000 () Hydrazine

........................................................................................................................................................................... 302-0 1-2 5,000 (b) Hydrochloric acid (solution, conc 25% or greater)

............................. I

..... ............................................ 7647-01-0 5,000 (') Hydrocyanc acid

............................................................................................................................................................... 74-90-8 500 ( b) Hydrogen chloridde (anhydrous)

......................................................................................................................................... 7647-01-0 1,000 b) Hydrogen fluoridde

.............................................................................................................................................................. 7664-39-3 500 ' b) Hydrogen peroxide (conc 52%)

...................................................................................................................................... 7722-84-1 5,000 ') Hydrogen selende

............................................................................................................................................................. 7783-07-5 500 (b) Hydrogen sulfide

................................................................................................................................................................ 7783-06-4 1,000 (' b) Iron, pentacatonyl-..

.......................................................................................................................................................... 13463-40-6 500 (b) Isobutyronitdte

.......................................................... .......................................................................................................... 78-82-0 10,000 (b) Isopropyl chlo .ofo.a.e

..................................................................................................................................................... 108-23-6 5,000 (b)

Lactonitnile

.......................................................................................................................................................................... 78-97-7 5,000 () Methacrylon trile

................................................................................................................................................................. 126-98-7 1,000 (b) Methyl bromide

.................................................................................................................................................................. 74--&3-9 5,000D O ' Methyl chloridde

................................................................................................................................................................... 74-87-3 10,000 ') Methyl chlo oratmate

.......................................................................................................................................................... 79-22-1 1,000 (b) Methyl hy

.............................................................................................................................................................. 60-34-4 5,000 (b) Methyl Isocyanate

.............................................................................................................................................................. 624-83-9 1,000 (',b) Methyl mercaptan

.............................................................................................................................................................. 74-93-1 1,000 (b) Methyl thlocyanate

............................................................................................................................................................. 556-64-9 10,000 (b) Methyltcb rosilane

.......................................................................................................................................................... 75-79-6 1,000 (b) Nickel carbonyl

........................................................................................ ;......................................................................... 13463-39-3 500 M t, Nitric acid

.......................................................................................................................................................................... 7697-37-2 5,000 (b) Nitric oxide

................................. :

....................................................................................................................................... 10102-43-9 1,000 (b) Nitrobenzene

...................................................................................................................................................................... 98-95-3 10,000 ) Parathion

........................................................................................................................................................................... 56-38-2 1,000 ) Peracetic acid

.................................................................................................................................................................... 79-21-0 1.000 ) Perchloromethylmrercaptan

................................................................................................................................................ 594-4 2-3 100() (b) Phenol (liquid)

.................................................................................................................................................................... 108-95-2 10,000 M Phosgene

........................................................................................................................................................................... 75-44-5 500 ( b) Phosphine

.......................................................................................................................................................................... 7803-51-2 1,000

h7) Phosphorus oxychloridde

.................................................................................................................................................... 10025-87-3 1,000 (b)

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TABLE I TO 

### §68.130.-LIST OF.REGULATED Toxic SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEA'I;: PREVENTION-Continued (Alphabetical Order-l0a Substances)

Chemical name CAS No. Threshold Basisfor quantity (Ibs) listing

Phosphorus trichlodde

................................... ..... ............................................ 7719-12-2 5,000 (b) Piperidine

........................................................ .. . .............................................. 110-89-4 5,000 (') Proplonltle

....................................................................................................... ............ 107-12-0 1,000 (') Propyl chloroformate

................................................. .............................. ............... 109-61-5 5,000 C') Propytenelrnine

...................................................................................................... 4.......................................................... 75-55-8 10,000 (h) Propylene oxide

................................................................................................................................................................. 75-56-9 10,000 () Pyridlne, 2-methyl-5-vnyl-

................................................................................................................................................. 140-76-1 1,000 e) Sulfur dioxide

......................................................................... 7446-09-5 1,000 ( ) Sulfuridc acid

....................................................................................................................................................................... 7664-93-9 5,000 () Suifur tetrafluodde

............................................................................................................................................................. 7783-60-0 11, 00 (b) Sulfur ti

doxide

..................................................................................................................................................................... 7446-11-9 1,000 ( b) Tetram ethyllead

................................................................................................................................................................. 75-74-1 1,000 (b) Tetranitmm ethane

.............................................................................................................................................................. 509-14-8 1,000 (b) Thlophenol

......................................................................................................................................................................... 108-98-5 1,000 ) Titanium tetrachlorlede

........................................................................................................................................................ 7550-45-0 500 () Toluene 2,4-diisocyanate

................................................................................................................................................... 584-84-9 1,000 () Toluene 2,6-dllsocyanate

................................................................................................................................................... 91-08-7 1,00 (') Toluene dilsocyanate (unspecified Isomer)

....................................................................................................................... 26471-62-5 1,000 ) Trichloroethylsllane

............................................................................................................................................................ 115- 21-9 1,000 ') Trimethylchlorosilane

......................................................................................................................................................... 75-77-4 1,000 (b) Vinyl acetate monom er ...................................................................................................................................................... 108-05-4 5,000 (b) Vinyl chloride

................................................................................................................ 4.....................................................1 75-01-4 1 10,000 1(-)

Basis for Listing: :Mandated for listing by Congress. bOn ENS ist, vapor pressure 0.5 mmHg or greater. .On EMS NLvapor pressure lessthan 0.5 mrnHg, but has been involved In accidents resulting in death or Injury. a Toxic gas. Listed based on toxicity of 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 Basis for quantity (Ils) listing

50-00-0

.......... Formaldehyde

..................................................................................................................................................................... 500 (b) 56-38-2

.......... Parathion

............................................................................................................................................................................. 1,000 () 57-14-7

.......... lmethylhydrazine

.............................................................................................................................................................. 5,000 (b) 60-34-4

.......... Methyl hydrazlne

................................................................................................................................................................ 5,000 C) 62-53-3

.......... Aniline

................................................................................................................................................................................. 5,000 ) 67-66-3

.......... Chloroformn

...................... .................................................................................................................................................... 10,000 (b,) 74-83-9

.......... Methyl bromide

................................................................................................................................................................... 5,000 ') 7 "-7-3

.......... M

ethyl chloride

.................................................................................................................................................................... 10,000 (,) 74-87-3......Methyl mhloide...................................................................

....... 10,000 (b) 74-90-8

......... Hydrocyanic acid

........................................................................................................................... . ..................................... 5000 (.)

75-15-0

.......... Car onhy l ide

... n.......................... ..................................................................................................................................... 10,000 (b,) 75-91-1

.......... Et ryle c apo tade

................................... ............................................................................. .................................................. . 1 0,000 (*)

75-15-0

.......... Car on disulfide.

................................................................................................................................................................. 500 (b)

75 5

- . . . ...- 21

-- 8in

. .. . .. .. . ... . . .. . . . .. . . .. .. .. . .. .. . ... . . .. . . . .. . . .. . . .. . .. .. . ... . . .. . . . .. .. de.
... . . . .. . . .. . .1 ,000 ('.b) 75-

- .......... ylene oxide............................

.................................................................................................................................... 000 (b) 75-44-5

. h. e n..........
.. h e

. .................................................................................................................................................................. 100 ( b) 75-55-8

.......... Propyleneimine

................................................................................................................................................................... 10,000 (b) 75-5-9

. Propylene oxide....

. . ................................................................................................................................................................... 10,000 (b) 75-74-1

.......... Tet methyllead

................................................................................................................................................................... 1,000 (,) 75-77-4

.......... T methylchlo si lane

......................................................................................................................................................... ,O0 (b) 75-78-5

.......... Dimethyld chorsil lane.....

...................................................................................................................................................... 1,000 (')

78- 7-7

.......... Metoyltriclor s ..................................................................................................................................................................... 5,000 (b) 75-86-5

.......... Acetone cyanohyd rin

................................................................................................................................................................ ,000 (b) 78-82-0

......... Isobutyronll e..................................................................................................................................................................... 10,000 (b) 78-97-7

......... Lactonie i

................................................................................................................................................................... ... ,000 ') 79-21-0

.......... Peracetic acid

............... .... ......................................................................................................................................... .. . 1,000 (b) 79-22-1

.......... M

ethyl chloroformate

..... ....................................................................................................................................... .. 1,000 (b)

918- 73

.......... Tolen ea 2,h lsoy e .................................................................................................................................................... . 1,000 (b) 98-95-7

.......... Nyabenz o e ................................................................................................................................................................. ... 1,000 (,)

98-16-8

....... Benzenem ne, 3-(tri luo omethyl)....

... ................................................................................................................................... ... 1,000 (b) 98-87-3

........ Banzai chlor ide.

................................................................................................................................................................... 1,000 (') 96-95-3

........ Nitrobenzene

. ....................................................................................................................................................................... 1 ,000 (b) 100-44-7

....... Benzyl chlor de

...................................................................................................................................................................... 1,000 C') 106-89-8

........ plchlom hydrin

. ................................................................................................................................................................. 10,000 () 107-02-8

....... Acrolein

............................................................................................................................................................................... 1,000 (b) 107-07-3

.... Chloroethanol........................................1,000 (b) 107-11-9

........ Alylamlnee

.......................................................................................................................................................................... 1,000 (') 107-12-0

...... Proopnltrnit

.... e...........................................................................................................................o,00 ') 107-13-1

..... Acrylyltoneit

..... e...................................................................................................................10,000 1,00 ')
107-15-3

........ Ethylenedlamine

............................................................................................................................................................... 10,000 () 107-16-4

........ Formaldehyde cyanohydrin

................................................................................................................................................ 5,000 C') 107-18-6

........ Alyl alcohol

.......................................................................................................................................................................... 5,000 (b) 107-30-2

....... Chloromethyl methyl ether

.................................................................................................................... ............................ 1,000 C)

HeinOnline -- 58 Fed. Reg. 5122 1993

### Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 193 / 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 Basis for Niquantity (lbs) listing

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-.... 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 13483-39-3

.... 13463-40-6

.... 19287-45-7

.... 26471--62-5

.... '4K Vinyl acetate monomer ...................................................................................................................................................... Isopropyl chorofom ate

................................................................................................... Cyciohexylamine

................................................................................................................................................................ 

### P eno (l u )

................................................................................................................................................................. Thiophenol

....... ........................................................................................................................................................... Propyl.hlorolo ate

........................................................................................ .................................................................. T ran .4-d

. tene..................................................................................................................................................... Piper ine

.................................................................................................................................................................... Dic roethyl ether

..................................................................................................................................................................... TDchloroethylal lane

............................................................................................................................. ............................. Crotonalr ehyde, (E)

............................................................................................................................. . ............................ M hac onl

. . . . . . . . . . . . . . . . . .............................................................................................................................................. Bent cyl on e ........................................................... ............................................................... ............................. Pyrd ne, 2-met y-5- nyl

............. ..................................................................................................................................... Etyldre elml v y

........ .................. ........................................................................ ....................................................... Ethylenelmlne

................................................ . ................................................................................................................. Hydrazne

......... . ...

. . ..... . .. . . . ....................................................................................................... Boron trhfluo

.. de com.ound with methyl ether (1:1)

.................................................................................... ..................... Tetrang h e

.......................................................................................................................................................... Chloromethyl eter

............................................................................... .......................................................................
Toluene 2,4 isocyanate

........................................................................................................... ....................................... Me "rc h loometh le

............. ..... ........... ........ ....... ... ....................... ............................................................................... Tolen 2iisocyana e .... ..................................... ............................ ................................................................................. . P r ch lor e

. ... captan

............................................................................................................................................ Methyl Isocyanate

................................................... .................................................................................

Cr tyla hyork e

.... d..............................................................................

............. ............................................................. Cr t doadey de.............

.................................................................................................................................... Sufur ioIdde

.................................................................................................................................................................... T ltanum te rach.orl e

..................................................................................................................................................... ron

trifluodde

.................................................................................................................................................................. Hydrogen chloride (anhydrous)

........................................................................................................................................... Hyron fluode

.......................................... ......................................... .......................................................................... Hydrognalod (anhydrous)

............................................................................................................................................... Ammooni (aueou (solution, conc 2% or greater)

.................................. Hydrogn (flu ie s t n, on 20 org e er ............................... ...................... ................................................................ Sulfuric a d d

............................................................. .................... .................................................................. Nitric acid

.......................................................................................................................................................................... Phosphorustr lodde

..................... ................................. ........................................................................ Hydrogen peroxide (coc> 52%/6)

...................................................................................................................................... Fluo ine

......................................................................................................................................................................... C lorine

............................................................................................................... .......................................................... Hydrogen sl.de

.................................................................. ............................................................................................. Hydrogen seleide

.............................................................................................................................................................. SHyr e t eflo kle

............................................................................................................................................................ A imonype aluodd e

..................................................................................................................................................... Aimenoustrch odde

............................................................................ .............................. . ......................................... Arsone.....hore............................................................................................ ...- ,-- - Prie...................................................n....................................................... Pho6ph ne

......................................................................................................................................................................... Phosphorus oxycanoree ................................................................................................................................................ CThoreed o e

............................................................................................................................................................... Nhtdc oxide

..... ... ............................................................................................................................................................... Boron trlchlodde

..................................... ................................. ............. .... . ..................................................................... Nickel carbonyl

.. .......................................... .............................................. ...................................................................... iron. pentacaronyl

............................................................................................................................................................. Diborane

..... .................................................................... ........... ............................................................... Toueeo is cy n teenseefedIomrd.........................s......................d......................). 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 5,0O0 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 1,0010 5,000 5,000 5,000 5.000 5,00C 1,000

500 1.000 1,000

500 1,000 1,00C 5,00C

50C 1,00C 1,000

50C 1,00 4.00C

5O( 500 50C 1,000 Basisfor UsItg: *Mandated for liting by Congress. On EHS list, vapor pressure 0.5 mmHg or greater On EHS lot vapor essure Is than 0.5 mmlg, but has been nvolved In accld@nt resukig in death or I ,ury.
Ld based on ioxiclty of hydrogen chloide, potential to release hydrogen chloride. and histoy ofsocit

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 J Basisl for I I quentliy (06) 1 flth'ng
I I I Acetaldehyde Acetylene

........ Bromoi- fluordhylene 1,3-Butadtene 1 75-07-0 10,000 (9) 74-86-2 10,000 () 598-73-2 10,000 ('
106-99-0 10,0001

HeinOnline -- 58 Fed. Reg. 5123 1993

### 5124 Federal Register / Vol. 58, No. 11 / Tuesday, January 19, 1993 / Proposed Rules

TABLE 3 TO 

### §68.130.-LIST OF REGULATED FLAMMABLE SUBSTANCES AND THRESHOLD QUANTITIES FOR ACCIDENTAL RELEASE PREVENTION-Continued

[Alphabetical Order--62 Substances]

Threshold Basis for Chemical name CAS No. quantity (Ibs) listing

Butane
.................................................................................................................................................................................... 106-97-8 10,000 1-Butane

.................................................................................................................................................................................. 106-98-9 10,000 ( 2-But ne .................................................................................................................................................................................. 107-01-7 10,000 (t Butene

..................................................................................................................................................................................... 25167--67-3 10,000 ( 2-Butene-c .s ........................................................................................................................................................................... 590-18-1 10,000 2-Butene-trans

........................................................................................................................................................................ 624-64-6 10,000 ( Carbon oxysuflde

.................................................................................................................................................................. 463-58-1 10,000 ( Chlo ine r noxide

.................................................................................................................................................................. 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 ) Cyclopropane

.......................................................................................................................................................................... 75-19-4 10,000 (
Dchlorosilane

.......................................................................................................................................................................... 4109-96-0 10,000 Difluoroethane

......................................................................................................................................................................... 75-37-6 10,000

Di lmethylamlne

........................................................................................................................................................................ 124-40-3 10,000 2,2-Dlmethylpropane

............................................................................................................................................................... 463-82-1 10,000 ( Ethane

..................................................................................................................................................................................... 74-84-0 10,000 ( Ethyl acetylene

........................................................................................................................................................................ 107-00-6 10,000 Ethylamine

.............................................................................................................................................................................. 75-04-7 16,000 ( Ethyl chloride

.......................................................................................................................................................................... 75-. 00-3 10,000 Ethylene

......................................................................................................... ....................................................................... 74-85-1 10,000 Ethyl ether

.............................................................................................................................................................................. 60-29-7 10,000 C) Ethyl mercaptan
...................................................................................................................................................................... 75-08-1 10,000 ) Ethyl nitte

.............................................................................................................................................................................. 109-95-5 10,000 Hydrogen

........................ .............................................. 1337-0 t00C)

o e

....................... .............................................................................................................. 1333-74 10,000 (9 Isobutanve

............................................................................................................................... :................................................. 75-28-5 10,000 ( Isopntane

.............................................................................................................................................................................. 78-78-4 10,000 (s) Isoprene

................................................................................................................................................................................. 78-79-5 10,000 ) Isopropylamine

........................................................................................................................................................................ 75-31-0 10,000 ) Isopropyl chloride

................................................................................................................................................................... 75-29-6 10,000 (S)
Methane

................................................................................................................................................................................ 74-82-8 10,000 ( Methylamine

............................................................................................................................................................................ 74-89-5 10,000 3-Methyl-l-butene

................................................................................................................................................................... .563-45-1 10,000 2-Methyl-i-butene

.......................................... ....................................................................................................... 5 3-46-2 10,000 (') Methyl ether

................................................... "......................................................................................................................... 115-10-6 10,000 ( Methyl formate

....................................................................................................................................................................... 107-31-3 10,000 ()
2-Methylpropene

..................................................................................................................................................................... 115- 11-7 10,000 1,3-Pentadiene

........................................................................................................................................................................ 504- 0-9 10,000
Peantane
................................................................................................................................................................................... 109- 6-0 10,000 ) 1-P ntene
................................................................................................................................................................................ 109-67-1 10,0001 ) 2-Pentene, (E)-

....................................................................................................................................................................... 646-04-8 10,000 ) 2-Pentene, (Z)-.

..................................................................................................................................................................... 627-20-3 10,000 ') Propadleane

............................................................................................................................................................................ 463-49-0 10,000 Propane
.................................................................................................................................................................................. 74-98- 10,000 (1 Propylene

................................................................................................................................................................................ 115-0 7-1 10,000 Propyne
................................................................................................................................................................................... 74-99-7 10,000 Silane

....................... ............................................................................................................................................................. 7803-62-3 10,000 ( Tetrafluoro thyl ene ................................................................................................................................................................. 116-14-3 10,000 ( Tetramethylsilane

.................................................................................................................................................................... 75- 76-3 10,000 () Trlchlorosilane

......................................................................................................................................................................... 10025-78-2 10,000 ) Tdfluoro- chloroethylene

.............................................................................. I

........................................................................ 79-38-9 10,000 ( Tdmethylamlne

........................................................................................................................................................................ 75-50--3 10,000 Vinyl acetylene

........................................................................................................................................................................ 689-97-4 10,000 Vinyl ethyl ether

..................................................................................................................................................................... 109-92-2 10,000 ) VInyl fluoride

..................................................................................................................... .75-02-5 10,000 Ct9
Vinylidene chloride

.................................................................................................................................................................. 75-35 -4 10,000 ) Vinylldne fluoride

................................................................................................................................................................... 75-38-7 10,000( l ( Vinyl methyl ether

................................................................................................................................................................... 107-25-5 10,000 (

Bass for Lwk 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 Basis for quantity (Ibe) listing

60-29-7

.......... Ethyl ether

........................................................................................................................................................................... 10,000 () 74- -82-8

.......... Methane

.............................................................................................................................................................................. 10,000 () 74-84-0

.......... Ethane

................................................................................................................................................................................. 10,000 ( 74-85-1

.......... Ethylene

.............................................................................................................................................................................. 10,000 ( 74-86-2

.......... Acetylene

............................................................................................................................................................................ 10,0001 () 74-89-5

.......... Methylan ne ....................................................................................................................................................................... 10,000 ( 74-98-6

.......... Propane
............................................................................................................................................................................. . 10,000

HeinOnline -- 58 Fed. Reg. 5124 1993Federal 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]

Chemical name Threshold I Basis for quantity (Ibs) I listing

Propyne

.............................................................................................................................................................................. Ethyl chloride

...................................................................................................................................................................... Vinnyl fluoride

...................................................................................................................................................................... Ethylarnine

.......................................................................................................................................................................... Acetaldehyde

.......................................................................................................................................................... ........... Ethyl mercaptan

.................................................................................................................................................................. Cyclopropane

.............................................................................................................................................................................. Isobutane

........................................................................................................................................................................... Isopropyl c o ........................................................................................................................................................... Iopropylam ne .................................................................................................................................................................... Vinylidene chlorde

............................................................................................................................................................. Difluoroethane

..................................................................................................................................................................... Vinyl ene fluoridde

.............................................................................................................................................................. Trlmetyla ne ................................................................................................................................................................... Tetramethylsilane

............................................................................................................................................................... Isopentane

.......................................................................................................................................................................... Isoprene

............................................................................................................................................................................. Trlfluorochloroethylene

....................................................................................................................................................... Mfl#

... 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

.......... 75-60-3

.......... 75-76-3

.......... 78-78-4

.......... 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

........ 463-68-1

........ 463-82-1

........ 504-60-9... 557-98-2

........ 563-45-1

........ 563-46-2

........ 590-18-1

........ 590-21-0

........ 598-73-2

........ 624-64-6. 627-20-3

........ 646-04-8

........ 689-97-4

........ 1333-74-0. 4109-96-0

...... 7791-21-1

...... 7803-62-5

...... 10025-78-2 25167-67-3

.... 1.-1lJ faOIOflA

................................................................................... Ethyl acetylene

................................................................................................................................................................... 2-Butene

............................................................................................................................................................................. V lmethyl

.. t.er...................................

................................................ Vnmthyrter

................................................................................................................................................................ Pentane

.... . ...................................................................................................................................................................... I-Pentane

............................................................................................................................................................................... Vinyl ethyl ether

.................................................................................................................................................................. Ethyl n otrlte

. .................................................................................................................................................................. Propylene

............................................................................................................................................................................ Methyl ether

........................................................................................................................................................................ 2-Methylpropene

................................................................................................................................................................. Tetrafluoroethylene

............................................................................................................................................................. Dimethylamine.........f...

...................................................................................................................................................... Cyanogen

......................... ...................................................................... . ........................................................................ Cyanogen

................................................................................................. . .. .. .. ................................. ..... Carbon oxysulie

................................................................................................................................................................... 2,2-D methylpropane

........................................................................................................................................................... 1,3-Pentadiene...............................................................................................................................................................

2-Chloropropylene

.............................................................................................................................................................. 3-Methyl-l-butne

.............................................................................................................................................................. 2-Methyl-1-butene

............................................................................................................................................................... 2-Butene-cis

........................................................................................................ ....................................................... 1-Chloropropylene Brom otrifluore yle.ne

.......................................................................................................................................................... 2-Butene-trans

.................................................................................................................................................................... 2-Pentene, (Z)

..................................................................................................................................................................... 2-Pentene, (E)

.................................................................................................................................................................... Vinyl acetylene

.................................................................................................................................................................... Hydrogen

........................................................................................................................................................................... Dichlorosilane

..................................................................................................................................................................... Chlorine monoxide

.............................................................................................................................................................. Slane

................................................................................................................................................................................ Tdchlorosilane

..................................................................................................................................................................... Butane

............................................................................................................................................................................... Basisfor Ust:

'Vltiefa"al liquid 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

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

BILUNG CODE 6660-50- 4 CAS No.

1 -Butane o.o........................................................I.........................................................................o............+..............................

........................................................................................................................................................

HeinOnline -- 58 Fed. Reg. 5125 1993