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46246

[6560-611

Title '40-Protection of Environment.

CHAPTER I-ENVIRONMENTAL

PROTECTION AGENCY

SUBCHAPTER C-AIR PROGRAMS

[FRL 937-5]

PART 50-NATIONAL TARIMARY AND

SECONDARY AMBIENT AIR -QUALITY STANDARDS

National Primary and -Secondary Ambient Air Quality Standards -for

Lead

AGENCY: Environmental Protection

Agency.

ACTION: Final rulemaking.

SUMMAY:--PA is setting a national

ambient air quality.-standard for lead

at a level of 1.5 micrograms lead per cubic meter of air .(g Pb/n), averaged over a calendar quarter. This

final rulemaking follows a 1976 court

order to list lead as-a criteriaipollutant

for the development of an ambient

standard, and the Agency's issuance of

a proposed standard on December 14,

1977. In response to comments received on the proposed standard, EPA

has changed the averaging period for

the standard from a calendar month

to a calendar quarter, and has clarified

the health basis used in selecting the

standard level.

In establishing the level of the final

standard, EPA has determined that

young children" (age 1-5 years) should

be regarded as a group within the gen- eral population that is particularly

sensitive to lead 'exposure. The final

standard for lead in air is -based on

preventing most children in the

United States from exceeding a blood

lead level of 30 micrograms lead per deciliter of blood (gg Pb/dl). Blood

lead 1evels above 30 -±g Pb/dl Are associated with the impairment of heme

synthesis in cells indicatedby elevated

erythrocyte protoporphyrin '(EP), which EPA xegards Ls adverse to the

health of. chronically exposed children. There are a number of-other-adverse health effects associated With

blood lead levels above 30 gg Pb/dl, in

children as well as in the general pop- ulation, including-the possibility that

nervous system damage may occur in

children even without overt-symptoms of lead poisoning.

DATES: Effective: October 5; 1978.

After promulgation, States will have

nine months (until July 5, 1979), to

prepare and submit to EPA plans for

attainment of the standard by no later

than October of 1982. EPA's final reg- ulations for the development of State

-RULES AND REGULATIONS

implementation plans appear elsewhere in this FEDERAL REGISTER.

FOR FURTHER INFORMATION

CONTACT:

Mr. Joseph Padgett, Director, Strategies and Air Standards Division,

Office of Air Quality Planning and

Standards, U.S. Environmental IProtection Agency, Research Triangle

Park, N.C. 27711, telephone 919-541-

5204.

AVAILABILITY OF RELATED INFORMATION

A docket (No. OAQPS-77-1) contain-

,ing the information used by EPA in

the development of the proposed

=standard isaVailable for public inspeetiori and copying between 8 a.m. arid

4:30 p.m., Monday through Friday, at

EPA's Central Docket Section, Room

2903B, Waterside Mall, 401 M Street

SW., Washington, D.C. 20460.

The Federal reference method for

collecting and. measuring lead and its

compounds in the ambient air is published ii appendix G to this promulgation. This FEDERAL REGISTER also cofltains proposed regulations under 40

CFR Parts '51 and 53 for equivalent

lead air monitoring methods, final

rules for the development of State implementation ' plans promulgated

under 40 CFR Part 51, and an advance

notice of proposed rulemaking under

40 CFR Part 51 for ambient monitoring in the vicinity of certain industrial

plants with lead emissions. Additional

information for the development of

the State implementation plans is con- tained in the document Supplementary Guidelines for Lead Implementation Plans. The environmental and

economic impacts of implementing

this standard are described in an environmental impact statement and an economic impact assessment. -These

documents are avdilable for public inspection and copying at the Central

Docket Section (address above). Copies

may be obtalmed upon request from

Mr. Joseph Padgett at the above ad-

-dress.

The documents Air Quality Criteria

-for Lead and Control Techniques for

Lead Air Enissions were issued af' the

-time of -proposal. The Control Tech- - niques Document is available upon re- quest from Mr. Joseph Padgett at the

above address. The Air Quality Criteria Document can be obtained from:

Mr. Michael Berry, Environmental

,Criteria and -Assessment Office, MD52," Office of Research and Development, U.S. Environmental Protection

Agency, Research Triangle Park, N.C.

27711, telephone 919-541-2266.

SUPPLEMENTARY INFORMATION:

BACKGROUND

Lead is emitted to the atmosphere

by vehicles burning leaded fuel and-by

certain stationary sources. Lead enters

the human body through Ingestion

and inhalation with consequent ab

sorption into the bloodstream and distribution to all body tissues. Clinical,

epidemiological, and toxicological

studies have demonstrated that expo- sure to lead adversely affects human

health.

EPA's initial approach to controlling

lead in the air was to limit the lead

emissions from automobiles, the prin-

-cipal.source of lead air emissions. Regulations for the phasedown of lead in

the total-gasoline pool were promulgated In 1973, and, following litigation,

modified and put into effect in 1976,

The Agency has also established regulations requiring th'e availability of no- lead gasoline for catalyst-equipped cars. EPA also intended to control

emissions from certain categories of

industrial point sources under section

ill of the Clean Air Act.

In 1975, the Natural Resources Defense Council (NRDC) and others

brought suit against EPA to list lead

under section 108 of the Clean Air Act as a pollutant for which air quality criteria would be developed and a nation.

al ambient air quality standard estab.

lished under section 109 of the Act.

The Court ruled In favor of NRDC.

(NRDC, Inc. et aL v. Train, 411 F.

Supp. 864 (S.D.N.Y., 1976) aff'd 545 1.

2d,320 (2d Cir. 1976).) EPA listed lead on March 31, 1976, and proceeded to

develop air quality criteria and the

proposed standard.

On December 14, 1977, EPA proposed a standard of 1.5 jtg Pb/m, calendar month average,, proposed the

Federal reference method for monitoring air lead levels, issued the documents Air Quality Criteria for Lead

and Control Techniques for Lead Air

Emissions and proposed regulations

for State implementation plans, EPA

'invited public comments during the

period from December 14, 1977, to

March 17, 1978, on the standard, refer- ence method, and the SIP regulations,

Additional comments on these matters

were provided to EPA at a public hearing held on February 15-16, 1978.

LEGISLATIvE REQUIREMENTS For NATIONAL AMBIENT AIR QUALITY STANDARDS

Sections 108 and 109 of the Clean

Air Act govern the development of na- tional ambient air quality standards.

Section 108 Instructs EPA to document the scientific basI9 for the standard:

Section 108(a)(2). The Administrator shall

issue air quality criteria for an air pollutant within 12 months after he has included such

pollutant in a list under paragraph (1). Air

quality criteria for an air pollutant shall ac. curately reflect the latest scientific knowl.

edge useful in indicating the kind and

extent of all Identifiable effects on public health-or welfare which may be expected from the presence of such pollutant in the

FEDERAL REGISTERe VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46246 1978
ambient air, in varying quantities. The criteria for an air pollutant; to the extent practi- cable, shall include information on- ' (A) Those variable factors (including atmospheric conditions) which of themselves or in combination witth other factors may alter the effects on public health or welfare

of such air pollutant; (B) The types of air pollutants which,

when present in the atmosphere, may interact with such pollutant to, produce an ad- verse effect on public health or welfare; and

(C) Any known or anticipated adverse effects on welfare.

Section 109 addresses the actual setting of the standard:

Section 109(b)(1). National primary ambient air quality standards, prescribed under

subsection (a) shall be ambient air-quality

standards the attainment and maintenance

of which in the judgment of the Administrator, based on such criteria and allowing an adequate margin of safety, are requisite

to protect the public health. Such primary standards may be Tevised in the same manner as promulgated. .

(2) Any national secondary ambient air

quality standard prescribed, under subsection (a) shall specify a leVel of air quality the attainment-and maintenance of which

in the judgment of the Administrator, based on such criteria, is requisite to protect the

public welfare from any known or anticipat- ed adverse effects associated with the pres- ence of such air pollutant in the ambient

air. Such secondary standards may be revised in the same manner as promulgated.

In order to conform to the requirements of section 109, EPA has based

the level of the lead air quality standard on information presented in the

criteria document pertaining to the

health and welfare implications of

lead air pollution. This is in contrast

to other sections of the Act under

which EPA considers economic costs

and technical availability of air pollution control systems in determining

emissions limitations. It is clear from

section 109 that the Agency should

not attempt to place the standard at , level estimated to be at the threshold

for adverse health effects, but should

set the standard at a lower level in

order to provide a margin of safety.

EPA believes that the extent of the

margin of safety represents a judgment in which the Agency considers

the severity of reported health effects,

the probability that such effects may

occur, and uncertainties as to the full

biological significance of exposure to

lead. I Comments resulting from external

review of the air quality criteria and

the proposed- standard highlight disagreements on a number of areas critical to EPA's rationale for the standard. However, the scientific data base

provided in the document Air Quality

Criteria for Lead is as extensive as that for any other regulated air pollutant. Also, at every stage of development of the air quality criteria and

the standard, EPA has facilitated and

received broad eiternal participation.

RULES AND REGULATIONS

EPA regards as inevitable the presence

of scientific disagreement and uncertainty about key factors relevant to

environmental standards. Provisions

of the Act requiring timely promulgation of the standard, and requirements

for periodic future review of air quality criteria and standards indicate con- gressional intent that the Agency proceed even where scientific knowledge

is not complete or full scientific con- sensus is absent.

SUMTARY OF GENERAL FmDinGs F!Rou

Am QUALITY CRITERIA FOR Lvw

Following the listing of lead as a cr- teria pollutant, EPA developed the

document, Air Quality Criteria for

Lead. In the preparation of this document. EPA provided opportunities for

external review and comment on three

successive drafts. The document was

reviewed at three meetings of the Subcommittee on Scientific Criteria for

Environmental Lead of EPA's Science

Advisory Board. Each of these meetings was open to the public and a number of individuals presented both

critical review and new information

for EPA's consideration. The final criteria document was issued on December 14, 1977.

From the scientific information in

the criteria document. EPA draws conclusions in several key areas with particular relevance for the ambient air

quality standard for lead.

1. There are multiple sources of lead

exposure. In addition to air lead, these sources include: Lead In paint and ink,

lead in drinking water, lead in pesticides, and lead in fresh and processed

food.

2. Exposure to air lead can occur directly by inhalation, or indirectly by

ingestion of lead contaminated food,

water, or nonfood materials including

dust and soil.

3. There is significant individual

variability in response to lead expo- sure. Even within a particular population, individual response to lead expo- sure may vary widely from the average

response for the same group. Certain

subgroups within the general population are more susceptible to the effects of lead or have greater exposure

potential. Of these, young children

represent a population of forbmost concern.

4. Three systems within the human

body appear to be most sensitive to

the effects of lead-the blood-forming or hematopoietic system, the nervous system, and'the renal system. In addition, lead has been shown to affect the

normal functions of the reproductive,

endocrine, hepatic, cardiovascular, immunologic, and gastrointestinal systems.

5.'The blood lead level thresholds

for various biologic effects range from

the risk of permanent, severe, neuro46247

logical damage or death as blood leads

approach and exceed 80 to 100 pg Pb/

dl in children down to the inhibition

of an enzymes system as low as 10 pg

Pb/dl.

6. Lead is a stable compound, ubiquitously distributed, which persists and

accumulates both in the environment

and in the human body. In developing

the proposed standard. EPA used

these findings to arrive at a standard

level of 1.5 pg Pb/m3, calendar month

average. This level was derived from

the Agency's judgment that the maximum safe blood lead level (geometric

mean) for a population of young- children was 15 pg Pb/dl and, of this

amount. 12 pg.Pb/dl should be attributed to nonair sources. The difference

of 3.0 pg Pb/dl was estimated to be the

allowable safe contribution to mean population blood lead from lead in the

air. With epidemiological data indicating a general relationship of 1:2 between air lead (pg Pb/m3) and blood

lead (pg Pb/dl), EPA determined that

the level for the proposed standard

should be 1.5 pg/l 3.

SummARY OF ANcTIPATED IMPACTS

While the level of the standard is

based on health considerations, EPA

has conducted econoffic and environmental studies to assess the potential

impacts of the standard selected. EPA

estimates that the existing regulations

for the phase-down of lead in gasoline,

combined with the increasing use of

no-lead gasoline for catalyst-equipped

cars, will result in attainment of the

standard in urban areas where automobile exhaust is the dominant source of air lead. No additional pollution

controls are anticipated for these

areas.

EPA's economic analysis does indicate that there may be significant

problems in attainment of the standard in the vicinity of nonferrous smelt- ers and other large industrial sources of lead emissions. This assessment is

based, however, on studies using general emission factors and plant con- figurations, combined with dispersion

modeling. In the development of State

plans to-implement the standard, EPA

is encouraging affected industries and

State agencies to gathe plant-specific

technical data, ambient air quality

data, and assessments of alternative

engineering controls. With this information, the Agency will be able to more accurately evaluate the impact

of the standard .and better consider

approval of alternative approaches to

emission control in the State plans.

Also, EPA is encouraging affected

firms and State agencies to evaluate in

the early design phase, strategies

which take into consideration the

workplace standard for airborne lead

which will be promulgated by the Occupational Health and Safety AdminFEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46247 1978
46248

istration (OSHA). EPA believes that

this :approach will facilitate application of control technologies which

meet the requirements of both agencies. In working-with OSHA to estimate the combined. impact of the

OSHA and EPA standards,'in coordinating compliance strategies, and in

reviewing State plans implementing

the ambient standard, EPA intends to

avoid an approach which would foster

uncertainty in the investment deisionsoof affected firms.

The Agency will make every effort

'to insure that all opportunities to

avoid plant closures are exam ined,

while at the same time 'assuring protection from clear risks to the public

health.

SuMARY. oF CoMNTs RECEIVED

During the comment period from

flecember 14, 1977, to March 17, 1978,

and at the public meeting on February

15-16, 1978, -EPA received 95 written

and oral comments addressing the proposed standard or -the requirements

for State implementation plans. All

comments opposing 'the -standard as

excessively stringent (25) came from

-xepresentatives of affected industries,

and 20 of these counter-proposed 5.0

ttg Pb/m, calendar quarter average, as the appropriate level for the standard.

Comments ,Received .Opposing the Proposed

standard of 1.5 lig/m' Calendar ,Month

Average asExcessively Stringent

Company Op- Enposed ' dorsed 2

AmaxLead &Zinc, . X , X

American Mining Congress ......... x M

American Petroleum Institute . X

ASARCO ............................................ X

Associated Octel Co., Ltd X X

Battery Councl InternationaL.... - - X Bethlehen.Steel Corp ........ .. . Bunker Hill Co. ............... * ............. X X

C & D_ Batterles vslon-o.......... x 7X

E. L du Pont de Nemours & Co.,

Inc .............. . ................ .. x X

ESA Laboratories, Inc ..................... X X

Ethyl Corp .................................. X x General Battery,Cor rp........... X X

General Motors.Corp-............... Getty Refining & Marketing Co X

HECLA Mining Co ........................... x Houston:Chemlcal .................. .X N

Hunt Oil C o. N

Kerr-M cKee Corp .......................................... Lead Industries Association ........... x X

'Nalco 'Chemical :X X

N L Industries,'In n. ....... x X

Prestolite BatteryDivision..... X X

Secondary Lead Smelters Association . ............................ x X

Shell Oil Co .............. -..... ..... x St. Joe Minerals Cor-.._...-.. X X

Texaco. Inc ..................... ............. x X United Machinery Group., .................. Vulcan Materials Co .............

'1.5 jg/rm, calendar month.

•. 5.0 pg/mr' calendar quarter (or other averaging

period).

Sueny: Forty-five comments received from 29

corporations or their representatives; 25 of the 29

firms opposed the proposed standard of 1.5 pg/m' calendar month -average; 20 endorsed an alternative

RULES AND REGULATIONS

standard'of-5.0 jg/nil. calendar.quarter-average (or other averaging period).

Four comments 'opposed the proposed standard on the grounds that it

,was -not sufficiently protective .of

health.

CoMMNrs RECEIVED OPPosno PROPOSED

LEAD AIR 'QUAiITY STANDARD OF 1.5 gg/m3 ,

-CALENDAR MONTH AVERAGE, IN .FAVOR OF A

MOR STRINGENT~ STANDARD,,

Natural Resources Defense Council

Dr. Sergio Piomelli, Director;, Pediatric- Iematology, -New -York -University Medical

Center Public Interest Campaign

University of Connecticut School of Med,

cine

- Comments suppoiting the level of

the proposed standard (17) came from

the medical community, Federal agencies, State :and local public health

'agenciesand public interest-groups.

COMMENTS -REcExvED ENDORSING PROPOSED

IYAn AIR QUALIrY STANmaR OF 1.5 Ag/m*,

CALENDAR MoNTa AVERAGE

-STATE AND LOCAL 'AGENCIES

California Department of Health

Wassachusetts Department of Public'Health

New York State Department of ,Environ- - mental Conservation

New York City Department of EnvironmentalProtection

Tennessee Department of-Public Health

'Wisconsin 'Department of 'Natural Re- sources

FEDERAL AGENCIES

Center -for Disease 'Control, Public Health

Service

Departmenlt of Transportation

-Food and Drug Administration

Occupational Safety and Health Administratiofi-'

PUBrc INTEREST'GROUPS AND THE MEDICAL

"Comritte -on Environmental Hazards,

American Academy of Pediatrics

D.C. Committee for Lead Elimination in the

District

League of Women Voters of the lUnited

States

National UrbanLeague.

Herbert 'Needleman, :Boston Children's Hospital Medical Center

University of' North Carolina 'School of

Public Health

In .addition, -EPA has received- numerous comments and correspondence

on the proposed standard after the official end of the comment period.

Though 'EPA-does not have a legal obligation to review these documents, -it

has, in the interest of fostering full

-public participation in the rulemaking

process, reviewed these comments and

correspondence as time permitted. As

with all other documents considered

_or examined by EPA as part of its decision process, these documents have

been placed in the public .docket and

have become part of the administrative record of this decision.

The comments received by EPA did

,not challenge three -aspects of the proposed standard:

1. The basic structure of the rdtionale used by the Agency .in deriving

the level of theproposed standard.

2. The selection of young children as

a population particularly at risk to

lead exposure.

3. The attribution of 12 1Ag Pb/dl out

of the target mean population blood

-lead level of 15 ig Pb/dl to nonair sources of lead for the purposes of setting the air standard.

Significant comments vere received,

however, on the following key areas relating to the standard:

1. The elevation of erythrocyte protoporphyrin (EP) as the first adverse

health effect with increasing lead exposure rather than the decline of he-

•mogl6bin levels.

2. The blood lead threshold level for

elevated EP.

3. The incidence of health effects In

populations residing in the vicinity of • industrial sources of lead particulate

emissions.

4. The relationship describing the response of lead In the blood to lead in

the air.

5. The statistical form and averaging

period for the standard.

6. The appropriate marginof safety.

7. The limitation of the standard to

the respirable fraction of total air lead

particles.

8. The economic Inpact of the standard. 9. The State implementation plan

regulations.

10. The Federal reference method

formonitoring lead air quality.

11. The administrative procedures

employed by EPA in the; development

of the standard and wthe provision for

public participation.

A review of the comments received

and their disposition has been placed

in the rulemaking docket (OAQPS-77-

1) ifor public -inspection., The following

,paragraphs summarize the significant

comments and present the Agency's

findings.

THE HEALTH SIGNIFICANCE OF ERYTHROCYTE PROTOPORPHYIIN ELEVATION

Ten commenters disagreed with

-EPA's conclusion -that 'the impairment

of heme synthesis indicated by elevated erythrocyte protoporphyrln (EP)

constituted an adverse health effect.

Reasons for this disagreement ineluded:

1. An elevated level of EP is not

itself 'toxic to the cells in blood or ,other tissues.

2. 'EP elevation, -while indicating a change in heme synthesis, does not in.

"-dicate an insufficient production of

heme, or hemoglobin.

3. 'EP elevation and the alteration Qf

heme synthesis does not imply impair-

.FEDERAL REGISTER, VOL .43, NO. 194-THURSDAY, -OCTOBER '5, 1978

HeinOnline -- 43 Fed. Reg. 46248 1978
RULES AND REGULATIONS

ment of other mitochondrial

tions.

4- EP elevation is not associated

impairment of other heme pro

particularly cytochrome P-450.

5. Elevated EP may be cause conditions other than exposur

lead, particularly iron deficiency.

Five commenters agreed with I

conclusions about the health si cance of elevated EP citing the ft

ing arguments:

1. The interference of lead in a

damental cellular metabolic fun

to the extent that there is acet

tion of a substrate is physiologic

pairment, even without the pre

of clinical evidence of disease.

2. It is prudent medical practi

intervene where subclinrcal indic

of physiological impairment are

ent.

3. The impairment of heme sy

sis resulting from genetic or di

factors places a child at enhancec

to lead exposure.

4. There is evidence to suggest

impaired heme synthesis may - the function of neural or he

tissue even at levels where heme

duction is sufficient for hematopc

AGENCY RESPONSE

EPA agrees with the commenI

ceived that the -initial elevation c as a result of exposure to lead,

indicating an impairment of hem(

thesis, may not be a disease state seen as a clinically detectable d(

in performance. However, the cr document points out (p. 1-13) tha

impairment does-increase progre

ly with lead dose.

-The hematological effects described

are the eariesf physiological impair

encountered as a function of ncreasin

exposures as indexed by blood lead

tions, as such, those effects may be c ered to represent critical effects of le,

posure. Although it may be argued titain of the initial hematological (

(such as ALAD inhibition) constitute

tively mild, nondebilitating symptoi

low blood lead levels, they nevert

signal the onset of steadily intensifyt verse effects as blood lead elivatio:

crease- Eventually. the hematologic

fects reach such magnitude that they

clear-cut medical .significance as Indi

of undue lead exposure.

The fact that other conditions,

as iron deficiency may also ii

heme synthesis, does not obviate cem that lead is interfering wit

essential- biological function. Tht

the possibility that a nutritional

ciency is an additional stress t(

heme synthetic system which mE crease the sensitivity of a child t

adverse effects of lead exposure. EPA notes that there -is ge

agreement that heme and hemc

taining proteins play important

in the oxygen fixation pathways

fune-- cells. While the effects of low-level

lead exposure on the heme synthetic

with pathway in erYthrold tissue have been

teins. extensively studied in part because of

the ease with which this tissue may be

d by obtained, other cellular metabolic-sys- re to tems utilizing heme are less well un- derstood. EPA does not have sufficient

PA's information to conclude that impairgnifi- ment of heme synthesis In other tisllow- sues is not of concern until blood lead

levels are reached greater than those

fun- associated with hematological effects.

rction The air quality criteria document does

nula- point out that this effect has been es- a im- tablished in other tissues and that

sence other dose-response factors may apply.

The effect of lead on the formation of ce to -heme Is not limited to the hematopbletic

ators system. Experimental animal studies have

pres- shown a lead effect on the heme-requiring

protein, cytochrome P-450. an integral part

nthe- of the hepatic mixed-function oxIdase

etary (chapter 11). the systemic function of which

risk Is detoxification of exogenous substances. Heme synthesis inhibitionm also takes place

that in neural tLmue. CP. 13-5.)

Lffect In summary, the criteria document

patic states:

pro- Elevation In protoporphyrinis considered

)iesIS. not only to be a biological Indicator of Impaired InItochondrlal function of erythrold tissue bit also an Indicator of accumulation

of substrate for the enzyme ferrochelatase. It therefore has the same pathophysologi- of EP 6al meaning as increased urinary 8-ALA

while (vide supra). For these reasons, accumulae syn- tion of protoporphyrln has been taken to In- or be dicate physiologieal Impairment In humans.

!cline and this clinical consensus Is expressed In

iteria the 1975 Statement of the Center for Dist this ease Control (CDC), USPHS. The criterion

used by CDC to Indicate an effect of lead on ssive- heme function Is an FEP level of 60 pg/dl In

the presence of a blood lead level above 30

above pg/dl whole blood.

rments More recent Information relating to

g lead threshold of lead effects Indicates that PEP

eleva- levels begin to increase at a blood lead value

onsld- of 15 to 20 pg Pb/dl blood In children and

ad ex- women and, at a somewhat higher value. 20

itcer- to 25 pg Pb/dl blood, In adult men. (P. 13-5.)

ffects EPA concludes that the state of elerela- vated EP must be regarded as poten- ms at

heless tially adverse to the health of young

,g.ad- children. While the onset or a mild ex- ns in- perience of this condition may be tolal ef- erated by an individual, as with other are of subclinical manifestations of Impaired

catom function. it is a prudent public health

practice to exercise corrective action

such prior to the appearance of clinical

apair symptoms. The criteria document re- con- ports that symptoms of anemia in chitth an dren may occur at blood lead levels of

!re is 40 pg/d. EPA has adopted 30 pg Pb/dl

defi- as a maximum safe blood lead level for

the individual children.

Ly Mh THE BLOOD LEAD THRESHOLD FOR ELEVATSthe E ERYTHROCYTE PROTOPORPHYRIN

neral Comments provided by ten organiza-"

-con- tions challenged EPA's conclusion

roles that the threshold for the elevation of

in all EP occurs in children at a blood lead

level of 15 pg/dL Evidence offered for.

a higher threshold included:

1. The threshold accepted by EPA is

based on a study in which an inappropriate statistical technique, probit

analysis, was employed.

2. Application of a more appropriate

technique, segmented line analysis, results in a higher threshold.

3. The study in" question excluded

data on children with blo6d lead Ievqls

in excess of 30 pg/d.

4. Other investigators have reported

higher thresholds.

Comments in support of the 15 pg/dl

threshold maintained:

1. It Is proper to exclude values con- sidered abnormal if the intent of the

analysis is to determine an unbiased

effect threshold.

2. Other studies have reported

thresholds with error bands which include 15 pg/dl.

3. Probit analysis Is an appropriate

technique and differs only slightly

from the results 6btained from segmented line analysis.

AGENCY RESPONSE

EPA agrees that the segmented line

technique provides a more accurate estimate of the correlation threshold of

EP elevation with increasing blood

lead, about 16.7 pg PbldL and for this reason considered changing its judgments as to the maximum safe blood

lead level for a population of children.

However, as the target geometric mean for a population is increased, a greater percentage of children in the

population will exceed the maximum

safe individual level of 30 pg PbfdL

EPA estimates that at a population

geometric mean of 15 pg Pb/d. 99.5

percent of children will be below 30 pg

Pb/dL At 16.7 pg Pb this percentage

falls to 98.7. EPA regards the number

of children predicted to be below 30 pg

Pb/dl as the critical health consideration. For this reason, EPA has maintained its estimate of a geometric mean of 15 pg Pb/dl as the target fbr

population blood lead.

THE INCIDENCE OF HEALTH EFFECTS Ilf

POPULATIONS RESIDInG Inr THE VICfl=-

TY OF INDUSTRIAL SOURCES OF LEAD

PARTICULATE EKSSIONS

Several comments cited situations in

which proximity to significant point sources of airborne lead emissions

appear to have little or no health

impact on resident populations. This was taken to imply that the air standard was not necessary to protect public

health.

AGENCY RESPONSE

EPA aclmowledges the variability of

the impact of exposure to air lead on the potential for adverse health conse- quences. It is clear that direct expo- sure to air lead is only one of the

FEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

46249

HeinOnline -- 43 Fed. Reg. 46249 1978
46250

routes through which human expo- sure occurs. It is for this reason that

the Agency has accepted the concept

that only a portion of the safe population mean blood lead level should be

attributable to air lead exposure. The

presence or absence of health effects

in an exposed population is influenced

by a variety of factoks including:,Meteorology, terrain ,characteristics, geo- lodical and anthropological history,

pdrsonal and domestic hygiene, the oc- cupations of the population members,,

and the food and nonfood materials

with which they come into contact.

Taking into account such variability, it

remains the Agency's belief that airborne lead directly and indirectly con- , tributes to the risk of adverse health

consequences and that sufficient clinical and epidemiological evidence is

available to form a judgment as to the

extent of this contribution. This evidence Includes epidemiological studies

showing higher blood lead levels in

urban areas where air lead levels were elevated in comparison to rural areas. There have also been a number of.

studies linking elevated blood lead

levels -to industrial sources of lead

emissions. With regard to the 1972

tudy at El Paso, Tex., by the Center

for Disease Control, the criteria document reports:

It was concluded that the primary factor

associated with elevated blood lead levels in

the children was ingestion or inhalation of

dust containing lead. Data on dietary intake

of lead were not obtained because the climate and proximity to the smelter prevent- ed any farming in the area. It was unlikely that the dietary lead intakes of the children

from near the smelter, and farther away were significantly different. (P. 12-15.)

With regard to the report of Yankel

et al. at Kellogg, Idaho, the criteria

document states:

Five factors influenced, In a statistically significant manner, the probability of a child developing an excessive blood lead

level:

1. Concentrations of lead in ambient air

2. Concentration of lead in soil (ppm). 3. Age (years). 4. Cleanliness of the home (subjective evaluation.coded 0, 1, and 2, with 2'signify- ing dirtiest).

5. General classification of the parents' occupation (dimensionless).

Although the strongest correlation found was between blood lead levels and air lead

level, the authors concluded that it was un- likely that inhalation of contaminated air

alone could explain the elevated blood lead

levels observed. (P. 12-16.)

THE APPROPRIATE RELATIONSHIP

BETWEEN LEAD IN AIR AND LEAD IN BLOOD

Several commenters questioned. the

Agency's estimate that, for children, one microgram of lead per cubic meter

air (g Pb/m results in an increase of

RULES AND REGULATIONS

two micrograms lead per deciliter

blood (jIg Pb/dl).

AGENCY RESPONSE

EPA has reviewed the studies discussed in the criteria document which

report changes in blood lead levels

with different air lead levels. The

Agency. believes that one of the

strongest epidemiological studies is

that by Azar et al. in.which personal

dosimeters were used to measure lead

intake. This eliminated some of the

uncertainty about the extent to which

air quality observations accurately re- flect actual exposure. From the Azar

data, the relationship of lead in the air

.to lead in the-blood, evaluated at 1.5

jig Pb/ma was 1:1.8. The Azar study

was,-however, limited to an adult pop-' ulation.

A clinical study of adults, Griffin et

al., gives roughly the same conclusion

for a group of adults confined to a chamber with controlled exposure to

lead aerosol. This study was conducted over a three month period with con- trol over lead ingestion. As air- lead

levels n the chamber were increased

from 0.15 ji Pb/m3 to 3.2 jig Pb/m3, the air lead to blood lead relationship was 1:1.7.

Because children are known to have

greater net absorption and retention

of lead.than adults, it is reasonable to assume that the air lead to blood lead

relationship for this sensitive population, exposed to air lead levels in the

range of the proposed standard, is

equal to if not greater than for adults.

EPA also notes that the air lead to

blood lead relationship is nonlinear

and may result in a higher ratio at

lower air levels.

In an epidemiological study of children near a smelter, Yankel et al., the

response of blood lead to air lead, av- eraged over :the exposure range, was 1.9. EPA believes that these studies as well as others reported in the criteria

document, support the criteria document's conclusion that:

Ratios between blood lead levels and air

lead exposures were shown to range general- ly from 1:1 to 2:1. These were not, however,

constant over the range or air lead concen- trations encountered. There are suggestive data indicating that the ratios for children are in the upper end of the range and may even be slightly above it. There is also some slight suggestion that the ratios for males are higher than those for females. (P. 12-

38.) -

THE STATISTICAL FORM AND PERIOD OF

THE STANDARD

One commenter expressed the view

that, due to the lognormal distribution

of measured air lead, a not-to-be-exceeded standard of 1.5 jg/m3

, calendar

month average, would require sources of air lead to achieve control of their

emissions to a geometric monthly mean of 0.41 jg/M3 in order to prevent

the occurrence of a violation. Another

comment expressed the opinion that,

with the normal operation of a 6-day,

sampling schedule, the number of

samples which could be collected In

the course of a calendar month would

not provide a statistically valid estimate of the actual lead air quality for

the period.'

Several comments questioned the

health basis for the selection of the

calendar month averaging period.

EPA RESPONSE

EPA accepts the consensus of com- ments received on the scientific and

technical difficulties presented by the

selectibn of a calendar month averaging period. The Agency believes that

the key criterion for the averaging

period Is the protection of health of

the sensitive population. In proposing

the 1.5 1ig/m 3 standard, EPA concluded that this air level as a ceiling would

be safe for indefinite exposure of

young children. The critical question

in the determination of the averaging

period is the health significance of

possible elevations of air lead ,above 1.5 jg/m3 which could be sustained

without violation of the average of 1.5

pg/m3. In the proposed standard, EPA

chose a monthly averaging period on the basis of a study showing an adjustment period of blood lead level with a change of exposure (Griffin et al.). Be- cause of the scientific and technical

difficulties of the monthly standard,

EPA has reexamined this question and

concludes that there Is little reason to

expect that the slightly greater possibility of elevated air lead levels within

the quarterly period is significant for

health. This conclusion Is based on the

following points:

(1) From actual ambient measure- ments, the distribution of air lead

levels is such that where the quarterly

standard is achieved, there Is little

possibility that there could be sus- tained periods greatly above the aver- age value.

(2) While It is difficult to relate the

extent to which a monitoring network

actually represents the exposure situation for young children, it seems likely

that where elevated air lead levels do

occur, they will be close to point of

mobile sources of lead air pollution.

Typically, young children will not en- counter such levels for the full 24-

hour period reported by the monitor.

(3) There is medical evidence indicating that blood lead levels recqulli.

brate slowly to changes in air expo- sure. This serves to dampen the

impact of a short-term period of expo- sure to elevated air lead.

(4) Direct exposure to air is only one of several routes of total exposure.

This lessens the Impact of a change in

air lead on blood leid levels.

FEDERAL REGISTER, VOL 43, NO, 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46250 1978
On balance, the Agency concludes

that a requirement for the averaging

of air quality data over calendar quarter -will improve the validity of air

quality data gathered without a significant reduction in the protectiveness of the standard.

THE APPROPRIATE MARGIN OF SAFETY

Several comments received by the

Agency criticized the proposed standard for incorporating an excessive

margin of safety. This. criticism was

based either on the view that the critical health effect,, impaired heme synthesis, was not of health significance

or on the view that, EPA had employed

conservative, estimates of the several

-factors used in calculating the standard which, when combined, resulted in

an excessively stringent standard.

Other comments were received

which expressed concern that the

standard had little or no margin of

safety, particularly for certain subgroups within the general population

of young children.

AGENCY RESPONSE

EPA does not agree that the impairment of heme synthesis is a physiological response to lead exposure that

is without health significance. While

EPA does not fid- that this impairment is necessarily serious to. health at

the point at which it first can be detected by the elevation of erythrocyta

protoporlphyrin, at a threshold in a

range of 15-20 pg Pb/di, the Agency

does believe that above blood levels of

30 pg Pb/dl this effect has progressed

to the extent that it should be regarded as an adverse health effect.

In determining the final ambient air

standard' for lead, EPA has used

margin of safety considerations princlpally in establishing a maximum safe

blood lead level for individual children

at 30 jg Pb/dl and in determining the

-percentage of children to be placed

below this maximum level, about 99.5

percent. Usini these factors, results in

a target geometric niean population

blood lead of 15 pg Pbfdl.

In establishing other factorsused in

calculating the standard, EPA has

used margin of safety in the sense of

making careful judgments based on

-available data, but these judgments

have not been at the precautionary extreme of the range of data available to

the Agency. In the case of the geometric standard deviation (GSD), studies

reviewed in the criteria document

showed a range of 1.3 to 1.5. A standard -based on a 1.5 GSD would be far

more stringent than using 1.3. EPA

took the 1.3,' however, because of its

concern that the total geometric

standard deviation -contains variation

attributable to monitoring and analytical methodology. In estimating the relationship between air lead and blood

RULES AND REGULATIONS

lead to be 1:2, the Agency used an epidemiological study of children near a

smelter, Yankel et al, where response

of blood lead to air lead averaged over

the exposure. range was 1 to 1.9. In

adopting- 12 pg Pb/dl as the part of

blood lead attributable to nonair

sources, EPA Is concerned that typical

levels for this component may be

much greater, and that regulatory actions by other public health piograms

may be necessary to achieve a 12 pg

level.

Because of the variability between

individuals in a population experlencing-a given level of lead exposure, EPA

finds it is impossible to provide the

same amount of margin of safety for

all members in the sensitive population, or to define the margin of safety

in the standard as a simple percentage. EPA does believe that the factors

It has used-in designing the standard

provide an adequate margin of safety

for a large proportion of the sensitive

population. The Agency does not believe. that this margin Is excessively

large or on the other hand that the air

standard can protect everyone from

elevated blood lead levels.

THE IMPORTANCE OF THE RESPIRABLE

FRACTION OF TOTAL AM LEAD LEVEL

The Agency received a number of

comments expressing concern that, because only a fraction of airborne particulate matter is respirabl% an air

standard based on total air lead is unnecessarily stringent.

AGENCY RESPONSE

EPA agrees that some lead particles

are too small or too large to be deposited in the respiratory system. EPA

cannot conclude, however, that particles outside of the respirable range do

not represent an exposure hazard. A

significant component of exposure can

be ingestion of materials contaminated

by deposition of lead from the air. In

addition to the indirect route of ingestion and absorption from the gastrointestinal tract, nonrespirable lead in

the environment may, at some point,

become respirable through weathering

or mechanical action. EPA concludes,

therefore, that total airborne lead,

both respirable and nonrespirable

fractions, should be addressed by the

air standard.

ECONOMIC IMPACE OF THE PROPOSED

STANDARD

A number of commenters were crtical of the Agency's economic impact

assessment, and argued that the forecast underestimated the severity of

the economic impact to certain lead Industries.

46251

AGENCY RESPONSE

The comments critical of the draft

impact statement did not include data

which would allow EPA to confirm the

possibility of more severe economic

Impacts on certain source categories

including primary and secondary lead

smelters which could have difficulty in

limiting emissions sufficiently to

assure attaining the standard in their

immediate vicinity. Under the Clean

Air Act, the primary responsibility for

implementing the standard is assigned

to the States and each State is required to submit a plan to EPA demonstrating how attainment is to be

achieved. The actual economfimpacts

of Implementation are difficult to estimate at this time since, following promulgation, States wil have 9 months

to develop and submit these plans to

EPA. The plans must demonstrate attainment as soon as practicable, but no

later than 3 years following the date

of plan approval. However, under certain circumstances, States may request;

up to a 2-year extension of this deadline. Other sections of the Clean Air

Act may be used with the Administrator's discretion to grant further extensions of compliance deadlines for impacted industrial facilities.

EPA cannot. at this time accurately

predict the impact of this standard,

but with the timetable in the Act, sees

no reason to expect imminent closure

of any facility. The Agency is committed to developing accurate data for

specific plants in cooperation with the

Industry and State agencies in order to

avoid the imposition, of mmecessaiy

controls. EPA's principal concern,

however, must be to follow the mandate of the Clean Air Act relating to

the protection of the public health.

EPA believes that the economic

Impact asessment is a reasonable forecast of the economic consequences of

implementation of the standard.

T= PROPOSED STATE nbOLEXATIOn

PLAN (SIP) REGULATIONs

A summary of comments and the

Agency response is included n the

preamble to the final regulations published elsewhere in this MlmErgA EG-.

ISTER.

THE FEDERAL REFERENCE METZOD FOR.

MONITORING LEAD AIR QUALITY

A summary of conments and the

Agency's disposition is included in the

preamble to the final method published elsewhere In this FEDERAL.EGTHE ADMINISTRATIVE PROCEDURES EMPLOYED BY EPA IN THE DEVELOPM[ET OP

TH PROPOSED STANDARD AD THE PROVIS16N FOR PUBLIC PARTICIPATION

Two conmenters requested that

cross examination of witnesses be alFEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER. 5, 1978

HeinOnline -- 43 Fed. Reg. 46251 1978
RULES AND REGULATIONS

lowed in the post-proposal public hearing on the proposed standard and implementation regulations. EPA also received a request to postpone the public

hearing and to extend the comment

period, citing the need to complete on- going studies.

AGENCY RESPONSE

Both the request for cross-examination and the extension of the comment period were denied by the

Agency. With regard to the request for

cross-examination, the Agency determined that, in light of the extensive

review already conducted, cross-examination was not likely to produce new

information or results that would justify such a-significant departure from

the normal rulemaking process. Also

the existence of the normal comment

period was sufficient to allow interested members of the public to raise

questions concerning the Agency's determinations. Further, due to the ex- tensive review opportunities available

at all stages of the regulatory development, an extension of the comment

perlbd was not believed to be sufficiently necessary to further delay the

schedule f6r preparation of the final.

rule.

°CLARIFICATION OF ELEMENTS OF TnE

STANDARD

From reviewing the comments re- ceived, EPA wishes to clarify the following points in the presentation of

the rationale for the final standard:

(1) EPA is making a distinction between the blood Jead level that, is the

threshold for detection of the biological effect, impaired heme synthesis,

and the blood lead level at which this

effect has progressed to an extent that

it is regarded as adverse to health.

(2) EPA is making a distinction between estimating a maximum safe

blood lead level for an individual child,

and establishing a population target

geometric mean blood lead level for

the sensitive population.

(3) EPA is making a distinction between what the contribution to blood

lead levels from nonair sources actually may be, and attributing a contribution from nonair sources for the purpose of standard setting.

DERIVATION OF THE NUMERICAL LEVEL OF

THE FINAL STANDARD

,EPA's objective in setting the level

of the standard is to estimate the concentration of lead in the air to which

all groups within the general population can be exposed for protracted periods without an' unacceptable risk to'

health.

This' estimate is based on EPA's

judgment in four key areas: (1) Determining the "sensitive population" as that group vithin the general population which has the lowest

threshold for adverse effects or greatest potential for exposure. EPA_ con- cludes that young children, aged 1 to

5, are the sensitive population.

(2) Determining the safe level of

total lead exposure for the sensitive

population, indicated by the concentration of lead in the blood. EPA con- cludes that the maximum safe level of

blood lead for an individual child is 30

jig Pb/dl and that population blood

lead, measured as the geometric mean,

rhust be 15 jig Pb/dl in order to place

99.5 percent of children in the United

States below 30 jg Pb/dl . (3) Attributing the contribution to

blood lead from nonair pollution sources. EPA concludes thaf 12 jIg Pb/

dl of population blood lead for children should be atttributed to nonair

exposure.

(4) Determining the air lead level

which is consistent with maintaining

the mean population blood lead level

at 15 jig Pb/dl. Taking into'account

exposure from other sources (12 jig

Pb/di) EPA has designed the standard

to limit air contribution after achieving the standard to 3 jug Pb/dl. On the

basis of an estimated 'relationship of

air lead to blood lead of 1 to 2, EPA

concludes that the ambient air standard should be 1.5 1zgFPb/m3.

Each of these four areas is discussed

- further in the following sections.

SENsITIVE POPULATION

EPA believes that the health of

young -children is at particular risk

from lead exposure.- This is because

children have a greater physiological

sensitivity to the effects of lead than

do adults and may have greater expo- sure to environmental lead from playing in contaminated areas. Other sensitive populations identified by EPA

include those occupationally exposed,

and pregnant women and their fetuses. Comments received on the proposed standard did not challenge

EPA's position that young children are the most sensitive populition for

determining the standard. A number

of comments did point out that within

the general population of children

there' were subgroups with enhanced

risk due to genetic factors, dietary deficiencies, or residence in urban areas.

EPA acknowledges the higher - risk

status of such groups but does not

have information either in the air

quality criteria or in the comments re- ceived for estimating a threshold for

adverse effects separate from that of

all young children. Concern about

these high risk subgroups has, however, influenced EPA's determination of

the percentage of the population of

children (99.5 percent) to be maintained below 30 jig Pb/dl.

EPA continues to' be. concerned

about the possible health risk of lead

exposure for pregnant women and

their fetuses. The stress of pregnancy

may place pregnant women In a state more susceptible to the effects of lead,

and,transplacental transfer of lead

may affect the prenatal development

of the child. There is, however, Insufficient scientific Information for EPA to

either confirm or dismiss this suggestion, or to establish that pregnant

women and fetuses are more at risk

than young children.

THE MAXIMuM SAFE EXPOSURE FOR

CHILDREN

In determining the maximum safe

exposure to lead for children, EPA has

taken the measurement of blood lead

as the indicator of total lead dose.

There are other possible indicators of

exposure, for example the level of zinc

protoporphyrin (ZPP), but most

health studies reported in the criteria

document utilize blood lead levels as indications of the mobile body burden

of lead. The criteria document reports

the following table of effect thresholds ,for children with increasing-blood

lead levels.

SUMMARY OF LOWEST OBSERV, MEf ECT LEVELS

IN YOUNG CHILIREN

pv Pb/dl

8-ALAD inhibition ..................... ............. 10

Erythrocyte protoporphyrin elevation 15-20

Increased urinary 8-ALA excretion .......... 40

Anemia ......................................................... 40

Coproporphyrin elevation ................... ... 40

Cognitive (CNS) deficits .................... 50-00

Peripheral neuropathics ......................... 50-00

Encephalopathic symptoms .................... 80-100

(P. 13-8)

The first physiological effect associ.

ated with increasing blood lead levels

is the Inhibition of the enzyme 8-aminolevulinic acid dehydratase (8-ALAD),

both in red blood cells (erythrocytes),

and In cells In other tissues. This

enzyme catalyzes the condensation of

two molecules of 8-aminolevulinle acid

(8-ALA) to form porphobilinogen, one

of the components involved in the cellular synthesis of heme. The criteria

document reports that the threshold

for 8-ALAD inhibition in children is 10

jig Pb/di.

At blood lead levels above 10 Ag Pb/

di, the function of 8-ALAD Is Increasingly inhibited by lead. The criteria

document states that 40 pg Pb/dl Is

the threshold for elevation of 8-ALA

recognized as 8-ALA in the urine or 8-

ALA-U, an indication that 8-ALA has

begun to accumulate In cells.

EPA does not regard the inhibition

of 8-ALAD above 10 jg Pb/dl as ad- verse to health because of the absence

of evidence that there Is an impairment of heme synthesis until a threshold of 40 jig Pb/dl Is reached. The ac- cumulation of 8-ALA above normal

levels, indicated by 8-ALA-U, Is re- garded as adverse to health, both because .of impaired heme synthesis, and

FEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

46252

HeinOnline -- 43 Fed. Reg. 46252 1978
the possibility that 8-ALA accumulation is itself toxic to cells.

The criteria document reports that

above a threshold of 15-20 pg Pb/dU

there is an elevation of protoporphyrin in erythrocytes. Protoporphyrin is an organic chemical compound used by all cells in the production of heme. In the final stage of

heme synthesis, erythorocyte protoporphyrin (EP) and iron are brought

together in the cell mitochondria. In

the presence of lead, this step is

blocked, possibly by inhibition of the

enzyme ferrochelatase or by interference-in the transport of iron across the mitochondrial membrane. Without

incorporation into heme, the levels of

protoporphyrin in the cell become elevated.

From review of the information provided by the air quality criteria document as wellas the evidence and arguments offered by medical professionals

commenting on the proposed standard, EPA has concluded that the effects of lead on the cellular syntheis

of heme, as indicated by elevated

erythrocyte protoporphyrin, are potentially adverse to the health of

young children. This appears, however, to be a question of the degree to

which the effect has progressed. EPA

does not believe that there is significant risk to health at the point where

the elevation of EP can first be corre- lated with an increase in blood lead

(15 to 20 jig Pb/dl). On the other

hand, EPA regards as clearly adverse

to health the impairment of heme

synthesis, and other effects of lead

which result in clinical symptoms of

anemia above 40 pLg Pb/dl. These effects are followed quickly by the risk

of nervous system deficits for some

children with blood lead levels of 50 pg

Pb/dl.

EPA has concluded that the maximum safe blood lead level for an individual child is 30 pg Pb/dl. This is

based on the following factors:

(1) The maximum safe blood lead

level should be somewhat lower than

the threshold for a decline in hemoglobin levels (40 pg Pb/dl).

(2) The maximum safe blood lead

level should be at an even greater distance below the threshold for risks of nervous system deficits (50 pg Pb/dl).

(3) The maximum safe blood lead

level should be -no higher than the

blood lead range characterized as undue exposure by the Center for Dis- ease Control of the Public Health

Service, as endorsed by the American

-Academy of Pediatrics, because of elevation of erythrocyte protoporphyrin

(above 30 pg Pb/dl).

(4) The maximum safe blood lead

level for an individual need not be as

RULES AND REGULATIONS

low as the detection point for the initial elevation of EP (15-20 pg Pb/dl).

The criteria document points out

that data from epidemiological studies

show that the log values of measured

individual blood lead values In a uniformly exposed population are nor- mally distributed with a geometric

standard deviation (GSD) of 1.3 to 1:5.

Using standard statistical techniques,

it Is possible to use the geometric

standard deviation to calculate the mean population blood lead level

which would place a given percentage

of the population below the level of an effects threshold. A GSD of 1.5 would

result in a lo*er geometric mean, and a more stringent standard. However,

because some of the variability in the

GSD is from measurement systems,

EPA has used a GSD of 1.3.

Recently, analysis of the data collected by New York City's Bureau of

Lead Poisoning has shown that populations of children In the New York area consistently have distributions of

blood lead values with a GSD of 1.4 to

1.5. With a geometric mean of 15.0 pg

Pb/di, a GSD of 1.4 results in about

two percent of the population over levels of 30 pg Pb/d. A GSD of 1.5

would place more than four percent over 30 pg Pb/dl. EPA is concerned

that such results may Imply that the

standard Is not as precautionary as It

would be if the actual GSD was 1.3.

However, the Agency's best estimate is

that some of the GSD is from analytical and monitoring variance, and for

this reason, EPA Is using the 1.3 value

in calculating the final standard.

In EPA's view, use of the 99.5 percent range Is not excessive. From 1970

statistics, there are approximately 20

million children In the United States

below the age of 5 years, 12 million in

urban areas, and 5 million In center

cities where lead exposure may be

high. Again, khowledge that there are special high risk groups of children

within the general population deters

EPA from considering lower percentages.

CoNTaIuTION To TOTAL Lnw

ExPosuRE FROM NONAM SouRcEs

In the proposed standard, EPA

.argued that the air standard should

take into account the contribution to

blood lead levels from lead sources un- related to air pollution. No, comments were received challenging this argument. EPA continues to base Its calculation of the.amblent air standard on

the assumptions that, to an extent,

the lead contribution to blood lead

from. nonair sources should be subtracted from the estimate of safe mean population blood lead. Without

this subtraction, the combined expo- sure to lead from air. and nonair

46253

sources would result in a blood lead

concentration exceeding the safe levelEPA notes that the level of the

standard Is strongly influenced by Judgments about nonair contribution

to total exposure, and that there are difficulties in attempting to estimate

exposure from various lead sources. Studies reviewed in the criteria document do not provide detailed or widespread information about the relative

contribution of various sources to children's blood lead levels. Estimates can only be made by Inference from other

empirical or theoretical studies, usually involving adults. Also, It can be ex- pected-that the contribution to blood

lead levels from nonair sources can very widely, is probably not in con- stant proportion to air lead contribution, and in some cases may alone

exceed the target mean population

blood lead leveL

In spite of these difficulties, EPA

has attempted to assess available information in order to estimate the

general contribution to population

blood lead levels from air and nonair sources. This has been done with evaluation of evidence from general epidemiological studies, studies showing deCline of blood lead levels with decrease

in air lead, studies of blood lead levels

in areas with low air lead levels, and

isotopic tracing studies.

Studies reviewed by the criteria document show that the geometric mean blood lead levels for populations of

children are frequently above 15 pg

Pb/dl. In studies reported, the range

of mean population blood lead levels

for children was from 16.5 pg Pbldl to

46.4 pg Pb/dl with most studies showing mean levels greater than 25 pg Pb/

dl (Fine, 1972; Landrgan, 1975; von Lindern. 1975). EPA believes thaf, for

many of these populations, the contribution to blood lead levels from nonair

sources may exceed the desired target mean blood lead level.

In a number of studies, reduction in

air lead levels resulted in a decline in

children's blood lead levels. A study of

blood lead levels in children in New

York City showed, that children's mean blood lead levels declined from

30.5 pg Pb/dl from 1970 to 1976, while

during the same period air lead levels

at a single monitoring site fell from 2.0

pg Pb/dl to 0.9 pg/Pb (Billick, 1977).

Studies at Omaha, Nebr. (Angle, 1977)

and Kellogg, Idaho (Yankel, von Lindern. 1977) also show a drop in mean blood lead levels with declines in air

lead levels. As air lead levels decline

there appears to be a rough limit to

the drop in blood lead levels. , EPA has also examined epidemiologIcal studies in the criteria document

where air lead exposure is low, and can be assumed to be a minor contributor to blood lead. These studies pro- vide an indication of blood lead levels

resulting from a situation where

nonair sources of lead'are predominant.

FEDERAL REGISTER, VOL 43, NO. 194-TURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46253 1978
46254 RULES AND REGULATIONS

STUDIES REPORTING BLOOD LEAD LEVELS IN CHILDREN EXPOSEDTO M ODERATE TO LOW Am LEAD

LEVELS

Investigator Blood Air lead 2 Comment

lead'

Hammer. 1972 ... . ......... ...... .............. 11.6 0.1 ............ Children in Helena, Mont.

Angle,1974 .................. ; .......... . . . 14.4 0.14 .................... Suburban Children ages 1 to -4 In

Omaha, Nebr.

Goldsmith, 1974 ...................... 13.7 0.2 to 0.7 .......... Children in Benecla Calif. 0.3 to'0.6

Children in.

JCrocket, Calif..

Johnson, TiIery, 1975............10. .... Female children-mean age 9 in

Lancaster Calif.

'In 2 micrograms of lead per deciliter.

In micrograms of lead per ctbic meter.

The range of mean blood lead levelsJin

those studies is from 10.2 jig Pb/dI to

14.4'lpg Pb/,dl, with an average at12.7

pg Pb/dl.

In addition to epidemiological investigations, EPA -has reviewed studies

that examine the -source of blood lead

by detecting characteristic lead isotopes. A study using isotopic tracing

(Manton, 19.77) suggests that for several adults in Houston, Tex., 7 to 41 per-.

cent of blood lead could be attributed

to air lead sources. An earlier isotopic

-study .(Rabinowitz, 1974) concluded

that for two -aduflt'male subjects studied, approximately one-third of total

daily intake of lead could be attributed to exposure to air lead levels of 1-2

pg Pb/m. While these results -cahnot

be directly related to children,- it 'is

reasonable to assume that children

-may exhibit the san3ie or higher percentages of air lead contribution to

blood lead level because of a greater

potential for exposure to indirect air

sources, soil and dust.

From reviewing these areas of :evidence, EPA concludes that:

1. In studies showing -nean blood

lead levels above 15 pg Pb/d, it is

probable that both air and nonair

sources of lead contribute significantly

to blood lead with the possibility that

contributions from ,nonair sources

exceed 15 pg Pb/dl.

2. Studies showing -a sustained drop

in air lead levels show a corresponding

drop in blood lead levels, down to 'an

,apparent limit in the range -of 10.2 -to

14.4 pg Pb/di.'

3. Isotopic tracing studies showt air

contribution to blood lead to -be 7-41

.percent in one study and about 33 percent In another study.

In considering -this evidence, EPA

notes that if, from the isotopic Studies, .aproxmatlytwo~thirds ,of blood

ieads typically derived from honair

sources, a-meanblood lead'target of 15

pg -Pb/di would attribute 10 lg Pb/dI

to non-air sources. On the other hand,

the average blood lead level from -the

limited studies available where air exposure was low is 12.7 )ig Pb/di. In the

absence of' more precise information,

EPA is calculating th6 lead standard

based on the attribution of 12 pg Pb/

dl of the-blood lead level in children to

lead sources unaffected by the lead air

quality standard. EPA is aware that

.actual population blood lead levels,

either individually or as a population

mean, may exceed this benchmark.

'However,- if EPA were to use a larger

estimate of non-air contribution to

blood lead, the -result would be an exceptionally- stringent standard, which

would-not address the principal source of lead exposure.

THE' RELATIONSHIP BE wN AIR m-AD

ExPosURE AND RESULTING - BLOOD

IXAD IZVL

E:A hai reviewed the studies discussed in the criteria -document which

report changes in blood lead levels

with different air Jead"levels. The

Agency , believes -that, one of the

strongest epidemiological studies is

that by Azar et al., which used person-

-aLdosimeters to measure lead intake.

This eliminated some of the ulicertainty ,about the extent to which air -quality observations accurately reflect

-actual exposure. From the Azar data,

the relationship of lead in the air to

lead in the blood, evaluated at 1.5 pg

-Pb/m,. was 1:1.8. The Azar study was,

however, limited to an adult popula-

-tion.

A clinical study of adults, *Griffin et

al., gives roughly the same conclusion

for a group of adults confined to a chamber with ontrolled exposure to

lead aerosol. This study was conducted over a'three month period with .control over lead ingestion. As air lead.

levels in the chamber were increased

from 0.15 -pg Pb/m3 .to 3.2 pg Pb/m3,

the air lead-to blood lead relationship was -1:1.7.

Because children are known to have

greater net absorption and retention

of lead than adults, it is reasonable to

assume that the -air lead to -blood lead

relationship for this sensitive population, exposed to air lead levels in the

range of the _proposed standard, is

equal to if not greater than for adults.

EPA also notes that -the air lead to

blood lead relationship is nonlinear

which will result in a higher ratio at

lower air levels.

In an epidemiological study of children near a smelter, Yankel et al., the

response of, blood lead to air lead, averaged over the exposure range, was 1.95. This study provided information

on the relationship of blood lead to air

lead over a very large range of air lead

values. The air lead values in the

study are the result of a model calibrated by monitoring data. The relative error, of the individual values, es.

pecially in the low range is larger thin

in the Azar study.

The authors of the study, Yankel

and von Lindem, chose a log-linear

model which provided a good fit to the

data and gave an estinated slope of

about 1.2 at an air lead of 1.5. However, EPA sees a problem with a loglinear model in that It forces a lower

slope at low air lead values and a

higher slope at higher lead values,

This is i-i direct 'contradiction to the

,Azar and the Griffin studies, both of

which indicate higher slopes at lower

air lead values.

Because of the uncertainties in the

low air lead values in the Idaho study,

,EPA -felt that the calculation of an

average slope or ratio over the entire

xange of data would be a moderate

compromise. The calculation of an average slope gives a value of 1.95.

EPA believes that these studies as well as others reported in the criteria document support the document's conolusion that:

ratios between blood lead levels and air lead

exposures were shown to range generally from 1:1 to 2:1. These were not, however,

constant over the range of air lead concen- trations encountered. There ar6 suggestive data Indicating that the ratios for children .are In the upper end of the range and may even be slightly above it. There is also some 'slight suggestion that the ratios for males are higher than those for females. (pp. 12-

38.)

CALCULATIoN oF TuE AIR STANDARD

EPA has calculated the standard

based on the conclusions reached In

the previous sections;

1. Sensitive population: Children. ages 1-5.

2. Health basis: Maximum safe blood lead

level for individual children Is 30 pg Pb/di

-based on concern for impaired heme synthe- sis above .30 pg Pb/dl and margin o1 safety for anemia above 40 jg Pb/d and ngrvous

system deficits above 50 pg Pb/dI.

3. Maximum safe geometric mean blood

lead for children based on placing 99,5 percent of the sensitive population below the

30 pg Pb/al level of concern: 15 pg Pb/d.

4. Estimate of blood lead level attributed

to non-air sources: 12 pg Pb/dl.

5. Allowable contribution to blood lead

frotm air sources after achieving the stand.

ard: 15 pg Pb/dl-12 pg Pb/dl=3 pg Pb/d.

6. Air lead concentration consistent with

blood lead contribution from air sources: 3

pg Pb/dlxl pg Pb/m3 air/2 pg Pb/dl

blood= 1.5 pg Pb/m.

FEDERAL-REGISTER, VOL 43, NO. 194-THURSDAY, -OCTOBER 5, 3978

HeinOnline -- 43 Fed. Reg. 46254 1978
SELECTION OF THE AVERAGING PERIOD

FOR THE STANDARD

Based on. comments received and

consideration by the Agency, the proposed- averaging period of a calendar

month is extended to a calendar quarter. EPA believes that this change will

significantly improve the validity of

lead air quality data which will be

gathered to monitor progress toward

attainment without placing an undue

burden of State and local environmental agencies, or significantly reducing

the protectiveness of the standard.

The Agency believes that the key

criteria for the averaging period is the

protection of the health of the sensitive population. In proposing the 1.5

jg Pb/m3 standard, EPA concluded

that -this air level was safe for young

children with an indefinie exposure

period. The critical factor in the determination of the averaging period is

the health significance of possible elevations of air lead above 1.5 gg Pb/m3

which could be encountered for short

periods without causing average levels

to exceed the standard. In the proposed standard, EPA chose a calendar"

month averaging period on the basis

of a study (Griffin et al.) showing an adjustment period of blood lead level

with a change in exposure. Because of

the scientific and technical difficulties

of the monthly stan~lard, EPA has

reexamined this question and concluded that there is little reason to expect

that the slightly greater possibility of

elevated air lead levels sustainable by

the calendar quarter standard is significant-for health. This conclusion is

based on the following factors:

(1) From actual ambient measure- ments, there is evidence that the distribution of air lead levels is such that

if the quarterly average was achieved

-there is little possibility that there

could be sustained periods greatly

above the averageyvalue.

(2) While it is difficult to relate the

extent to which a monitoring network

actually represents the exposure situation for young children, it seems likely that where elevated air lead levels do

occur, they will be close to point or mobile sources. Typically, young children will not encounter such levels for

the full 24-hour period reported by

the monitor.

(3) There is medical evidence indicating that blood lead levels reequilibrate slowly to changes in air expo- sure. This serves to dampen the

impact of a short-term period of exposure to elevated air lead.

(4) Direct exposure to air is only one of several rputes of total exposure.

This lessens the impact of a change in

air lead on blood lead levels.

On balance, the Agency concludes

that a requirement for the averagingof air quality data over a calendar

quarter will improve the validity of air

RULES AND REGULATIONS

quality data gathered without a significant reduction in the protective- ness of the standard.

MARGIn OF SAFE

The Clean Air Act instructs EPA to

set the level of an ambient air quality

standard at a level which protects the

public health with a margin of safety.

One approach to using margin of

safety is to estimate the air concentration of a pollutant that Is the threshold for the first adverse effect detected with increasing air levels, and then

set the air standard at a somewhat

lower level. The extent of the safety

margin between the standard and the

estimated threshold for adverse effects is influenced by such factors as the severity or irreversibility of effects, the degree of uncertainty about

known or suspected health effects, the

size of the population at risk, and possible interactions of several pollutants

in potentiating health effects. While

the margin of safety is basek on available scientific information, this factor

is judgmental in that the AdminI trator must weigh the acceptability of es- timated risk.

Estimating an appropriate margin of

safety for the air lead standard in

complicated by the multiple sources and media for lead exposure. Because

of this, EPA has elected to use margin

of safety considerations in estimating

the maximum safe level for blood lead,

and the percentage of the sensitive

population to be placed below this

level, rather than making a final adjustment to concentration of lead in

the air. EPA has adopted 30 pg Pb/dl as the maximum safe blood lead level

for individual children, and the air

standard is calculated to maintain

most children below this target. On

the basis of Information developed in

the criteria document and from public

comment, blood lead levels between 30

and 40 pg Pb/dl are associated with

impairments of the heine synthetic

pathway which EPA regards as ad- verse to health. Blood lead levels

above 40 pg Pb/dl are associated with a decline in hemoglobin levels, and

levels above 50 jig Pb/dl are associated

with the risk of nervous system deficits for some children. With a geometric mean population blood of 15 pig Pb/dl lead, most children will be well

below these'thresholds, but a small

percentage can be expected to have

blood lead levels of concern. Because of the variability between

individuals in a population experiencing a given level of lead exposure, EPA

finds that it is not possible to provide

the same amount of margin of safety

for all members in the sensitive popu- lation, or to define a margin of safety

in this standard as a simple percentage. In developing the numerical level

of the standard, EPA used evidence in

46255

the criteria document that the blood

lead levels for individuals in a given

population of children are log-normally distributed. The statistical properties of this distribution make it possible to calculate the percentage of the

population which will fall below any

given blood lead level. Individuals at

each of these levels would have a" different margin of safety below the

maximum safe blood lead level. As'a

rough example, with a population of

children with a geometric mean blood

lead of 15 pig Pb/di, 86 percent of the

children would be below 20 pug Pb/dl,

97.5 percent would be below 25 pig Pb/

dl and 99.5 percent would be below 30

pg Pb/di. Assuming a population of

children In central urban areas where

air lead was at the standard level,

693,000 children would be over 20 lg

Pb/d, 126,500 oier 25 pug.Pb/d, and

20,605 above 30 pg Pb/di.

In determining the appropriate

margin of safety, the Agency has also

included consideration of the &following factors:

(1) In addition to the health effects

discussed, the "Air Quality Criteria.for

Lead" report multiple biological involvements of lead in practically all

cell types, tissues, and organ systems.

The significance for health of these

has not been fully studied.

(2) There are no beneficial effects of

lead at current environmental levels.

(3) EPA has incomplete data about

the extent to which children are indirectly exposed to lead from air lead

which moves to other environmental

media, such as water, soil and dirt, and

food.

(4) Lead is chemically persistent and

with continued uncontrolled emissions

will continue to accumulate both in

human tissue and in the environment:

(5) There is a possibility that lead

expospre resulting in blood lead levels

previously considered safe may in fact

influence the neurological development and learning abilities of the

young child. EPA does not have evidence, however, that provides more than a suggestion that this could occur at blood lead levels below 30 Pb/

dl for individual children.

TMPACT OF LEAD DUSTrALL ON BLOOD LEAD

In the preamble for the proposed air

standard for lead, EPA pointed out

that the significance of dust and soil

lead as indirect routes of exposure has

been of particular concern in the case of young children. Play habits and

mouthing behavior between the agqs

of 1 and 5 have led to the conclusion

*that greater potential may exist in

these children for ingestion and inhalation of the lead available in contaminated dust and soil. EPA is also con- cerned that the deposition of lead particles can lead to general contamination of the environment and increased

FEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46255 1978
46256

lead exposure from surface waters and

foodstuffs.

Studies -reviewed in the criteria document indicate a correlation between

soil and dust levels and childrens'

blood lead levels in highly contdiminated environments (Yankel and Von Lindern, 1977; Barltrop, 1974; Galke, in

press). The lead threshold for concern

has been reported as'1,000 parts per million (ppm) in soil (Yankel and von

Lindern, 1977). At levels of between

500 and 1;000 ppm in soil; the criteria

document concludes that 'blood lead

levels begin to increase. A twofold -increase in soil concentration in this

range is predicted to result in a 3-6

percent rise in blood lead levels. Below

500 ppm lead -in soil, no correlation

has been observed with blood lead

levels. *- The normal background for lead in

soil is cited in the criteria document as

15 ppm. Due to human activities, the

average levels in most -areas of the

United States are considerably-higher. Soil studies conducted by EPA's Offise

of Pesticides Programs from 1974 to

1976 in 17 urban areas reported onlyk3 ,cities with arithmetic mean concentrations in excess of 200 ppm, with the

highest valud 537 ppm. Concentrations

in the soils surrounding large point

sources of lead emissions, or heavily travelled roads may reach many thousand ppm.

Because of 'the many factors involved, EPA is unable to predict the

relationship between air lead levels, dustfail rates, and resulting soil accumulation.. Complicating factors include: Particle size distribution, rainout, other meteorological iactors, to- ";pographical features affecting deposition, and removal Iechanisms.

EPA believes, however, that -significant impacts on blood lead- of -soil nd

dust lead are mainly limited to areas

of high soil concentration (in excess of

1,000 ppm) around large point sources

and heavily- travelled roads. Evidence

suggests that soil lead-levels in, areas

with air lead levels in the range of the

standard are below the" threshold for

,lead health impact (Johnson, Tillery, 1975; Johanson, 1972; EPA, 1975 Air

Quality Data and Soil Levels).

Comments ,received on the proposed standard argued that the lead -air

standard should be limited -to respira- ble size lead particulate matter, as

larger' particles would fall to the

ground without being deposited or absorbed in the lung. "EPA has decided

not to accept this recommendation because, as discussed above, larger parti: cles can contribute to lead dose by human ingestion of airborne particles, by contamination of other environmental media, or by eventual reduction to respirable size by mechanical

action or weathering.

RULES AND REGULATIONSWELFARE EFEcTs

Comments received on the proposed

lead air quality standard did not address the issue of welfare effects or the need-for a secondary air quality

standard more restrictive than the primary standard. EPA maintains its position that the primary air quality

standard 'will adequately protect

against known and anticipated adverse

effects on public welfare. EPA 'does

not have evidence that a more restrictive secondary standard would be justified.

Available evidence cited in the crite-

'ria document indicates that animals

-do not appear to be more susceptible

'to adverse effects from lead than man,

,nor do adverse effects in animals occur at lower levels of exposure than. com- parable effects in humans.

Lead is absorbed but not accumulat- - ed to any great extent by plants from

soil. Lead is, either unavailable to

plants or is fixed in the roots and only .small amounts are transported to the

above ground iportions. Lead may be

'-deposited on the leaves- of-plants and

,present a hazard to grazing animals.

Although some plants may be susceptible to lead in the natural environment, it-is generally in a form that is

largely nonavailable to them. ' There is no evidence to indicate that

ambient levels of lead result in significant damage to manmade materials.

Effects of -lead on visibility and climate are minimal.

Based on such data, EPA promulgates the secondary air quality standard for lead at 1.5 pg Pb/m 3

, calendar

-quarteraverage.

EcoNomicIMPaAcT ASSESSMENT

-As, required by Executive Orders

11821 and 12044, EPA has conducted a general analysis - of the economic

-impact which might xesult from the

impleme;ntation of 'the lead xegula- tions. This arialysis was not intended

for nor was it used in the development or promulgation of the standard, and was issued for informational purposes

only. I I

The economic impact assessment

points out that the categories of sources likely to be affected by control

of lead emissions are primary lead and

copper smelters, secondary lead smelters, gray iron foundries, gasoline lead

'additive manufacturers, and lead storage battery manufacturers. This analysis further indicates that some primary and secondary lead smelters and

copper smelters may be severly

strained economically in achieving

emission reductions that may be re- quired in implementing the proposed

air quality standard. -

There are, however, uncertainties as- sociated with evaluating the impact-of

attaining the standard. For smelters

and foundries, -attaining the standard

may require control of fugitive lead

emissions, i.e., those emissions escap.

ing from individual process operations,

other than emissions from smoke

stacks. Fugitive emissions are difficult

to estimate, measure, and control; and

it is also difficult to predict their

impact on air quality near the facility.

From the information available to

EPA, nonferrous smelters may have

great difficulty in achieving lead air

quality levels consistent with the proposed standard in areas immediately

adjacent to the smelter complex.

The change in averaging time from a monthly average to a calendar quarter

average will affect the economic Impacts associated with the lead stand.

ard because for a given level of the

standard, a longer averaging period is

theoretically less stringent than" a shorter averaging period.

OTHR LEAD REGULATORY AND CONTROL

PROGRAMS

EPA's ambient air quality standard

is only one of a nuber of Federal,

State, and local programs designed to

limit exposure to lead.

In 1975, EPA promulgated the na- tional interm primary drinking water

regulation setting a maximum con. taminant level for lead. The standard,

aimed at protecting children from

undue lead exposure, was'set at 50 pg

Pb/liter. In 1977, the National Academy of Sciences concluded that a lead

level at which adverse health effects are observed cannot be set with assur- ance at any value greater than 25 yg

Pb/liter. The Office of -Drinking

Water is currently considering the

need to revise the interim drinking

water standard for lead,

Based on Its toxicity, EPA has n. cluded lead on Its list of priority water

pollutants for which effluent guide.

lines are being developed under the

Clean Water Act. Effluent guidelines are being developed for lead for non- ferrous smelters, based on achievement of best available technology.

EPA's Office of Pesticide Programs

,has promulgated regulations based on the toxicity of lead which require the

addition of coloring agents to the, pesticide lead arsenate and specify disposal procedures for lead pesticides. Use

of lead in pesticides is a small and decreasing proportion of total lead con- sumption in the United States.

The Resource Conservation and Recovery Act (RCRA) of 1976, through

which EPA Is to establish standards on how to treat, dispose, or store hazardous wastes, provides a means for

specifying how used crankcase oil and

other. waste streams containing lead

should be recycled or safely disposed

of. Regulatory actions related to

wastes containing lead are currently

being developed under subtitle C of

RCRA.

FEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46256 1978
EPA has regulations for reducing

the average lead content in the total

gasoline pool to 0.5, grams/gallon by

October 1, 1979, and Tegulations providing for lead-free gasoline required

for cars equipbed 'with catalytic con- verters and other vehicles certified for use of unleaded fuel. The former regulations are based on reducing exposure

to airborne lead to protect public

health. Other EPA actions which

result in the reduction of airborne

lead levels include ambient standards

and State implementation plans for

other pollutants such as particulate

matter and sulfur dioxide and new source performance standards limiting

emissions of such pollutants. Existing

and new sources of particulate matter emissions generally use control techniques which reduce lead emissions as one component of particulate matter.

The Occupational Safety and Health

Administration 'proposed regulations

in 1975 to limit occupational exposure

to lead to 100 pg Pb/ni3, 8-hour timeweighted average. The exposure limit was based on protecting against effects, clinical or subclinical, and the

mild symptoms which may occur below 80 pg Pb/dL providing an adequate margin of safety. The level of

100 gg Pb/m 3 is anticipated to limit

zblood lead levels in workers to a mean 40 pg Pb/dl and a maximum of 60 pg

PbjdL OSHA is presently reviewing

the latest information on lead expo- sure and health effects in preparation

for- promulgation of the workplace

standard for lead.

The Department of Housing and -

Urban Development (HUD) has re- quirments for reducing human expo- sure to lead through the prevention of

lead poisoning from ingestion of paint

from buildings, especially residential

dwelling. Their activities include (1)

prohibition of the use of lead-based

paints on structures constructed or re- habilitated through Federal funding

and on all HUD-associated housing; (2)

the elimination of the immediate

hazard from lead-based paint; (3) notification of purchases of HUD-associated housing constructed prior to 1950

which may contain lead-based paint;,

and (4) research activities to develop

improved methods of detection and

elimination of lead-based paint haz-.

ards, and the nature and extent of

lead poisoning.

The Consumer Product Safety Commission (CPSC) promulgated regulations in September 1977 which ban: (1)

Paint and other surface coating materials containing more than 0.06 percent lead; (2) toys and other articles

intended for use by children bearing

paint or other similar surface coating

material containing more than 0.06

percent lead; and (3) furniture coated

with materials containing more than

0.06 percent lead. These regulations

RULES AND REGULATIONS

are based on CPSC's conclusion that It

is in the public Interest to reduce the

risk of lead poisoning to young children from ingestion of paint and other

similar surface-coating materials.

The Food and Drug Administration

(FDA) adopted in 1974 a proposed tol- erance for lead of 0.3 ppm in evaporated milk and evaporated skim milk.

This tolerance is based on maintaining

children's blood lead levels below 40 pg

Pb/dL FDA has also proposed an action level of 7 pg Pb/ml for leachable lead in pottery and enamelware,

although the exact contribution of

such exposure to total human dietary

intake has not been established.

The Center for Disease Control

(CDC) concluded in 1975 that undue or increased lead absorption exists

when a child has confirmed blood lead

levels of 30-70 pg Pb/dl or an EP elevation of 60-189 pg Pb/dl except

where the elevated EP level Is caused

by iron deficiency.

In developing the lead air standard,

EPA has estimated both individual

and population blood lead levels which

it regards as safe targets. The Agency

believes that these targets do not nec- essarily serve as precedents for other

regulatory programs. There bre three reasons for this view:

(1) These targets were selected on

the basis of what the Clean Air Act re- quires. Other programs have other legislative requirements which would lead

to adoption of different but equally legitimate goals.

(2) The scientific data provided by

the air quality criteria allow compari- son of air levels with blood lead levels,

but analogous information Is not available for other media. At this time,

there does not appear to be the same extent of information about the

impact on blood lead of lead in food.

water, and nonfood ingested Items. Be- cause of this, FDA, CPSC and other

EPA standards have been based on es- timates of acceptable daily dose rather

than on blood lead targets.

(3) Studies currently underway may

provide new information relevant to

estimating safe levels of lead exposure.

Commlrs Br Orn s FEAL AGscrrs

Comments on the proposed lead air

quality standard were received from

eight Federal Agencies. Five of the

Agencies endorsed the air standard

while three of the Agencies commented on specific Issues and neither en- dQrsed nor opposed the standard. The

Center for Disease Control and the

U.S Public Health Service voiced support for the proposed standard of 1.5

pg Pb/m and urged basing the decision on the standard solely on considerations of public health. CDC Is fully

satisfied that EP elevation does indeed

represent a subclinical manifestation

of lead toxicity and that young chil46257

dren are the population most at rlik

from lead exposure, while some subgroups of children are at special risk

to lead because of conditions such as

malnutrition, genetic factors,- or iron

deficiency.

The Consumer Product Safety Commission endorsed the approach and

some of the Judgments made in arriving at the proposed air standard.

CPSC concurred with the position that children are the population at enhanced risk to lead exposure, and that

the goal of a mean population blood

lead level for children of 15 pg Pb/dl is

sufficiently low to be protective of the

population at enhanced risk of exposure. CPSC views the selection, of EP

elevation as the adverse health effect

of concern as open to challenge and

suggests basing the standard on a

more generally recognized severe

health effecL CPSC condurs that the

contrbuton..of nonair sources to lead

body burden must be evaluated in setting the air standard and suggests that

a larger nonair contribution, such as

13.5 pg Pb/dl used in the California

standard. might be considered.

The Food and Drug Administration

commended EPA's proposal of an ambient air quality standard for lead.

FDA agrees that children aged 1-5

years old comprise the most critically sensitive population. FDA concurs

that 15 pg Pb/dl is a reasonable maximum blood lead level to use as an

average national goal for children

aged 1 to 5, although FDA suggests that for young children the margin of

safety is disturbingly narrow. The division of the 15 pg Pb/dI into 12 pg Pbh

dl for nonair sources and 3 pg Pb/dl

for air sources was not unreasonable

in FDA's view.

The Occupational Safety and Health

Administration endorsed EPA's pro- posed standard for lead and agrees

with EPA that 15 pg Pb/dl as an average national blood lead level goal for

young children is reasonable. OSHA

views their proposed standard of 100

pg Pb/m, 8-hour time-weighted average, and their establishment, of 40 pg Pb/dl as the threshold effect level for

workers as consistent with the EPA

proposed standard.

The Department of Transportation (DOT) endorsed the proposed standard of 1.5 pg Pb/m. Based on an analysis of the impact of the proposed standard on the highway program, DOT concluded that it is highly prob- able that transportation-related violations of the proposed standard would

be limited to large urban areas.

In commenting on the proposed standard,.the Department of the Interior (DOI) expressed concern that the

burden for meeting the proposed standard will fall primarily on lead

and copper smelters and battery manufacturers, and commented on theFEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46257 1978
46258

impact of lead dustfall on ground

water quality. The Tennessee Valley

Authority provided specific comments

on the proposed State implementation

plan regulations and the proposed

Federal reference method. The De-.

partment of Commerce offered comments on the potential impacts of the

standard, pointing out that more con- sideration should be given to the potential impact of the standard on the

petroleum industry.

THE FEDERAL REFERENCE METHOD

The reference method for the determination of lead in suspended particulate matter collected from ambient air

describes the appropriate techniques

for determining the concentration of

lead and its compounds as measured as elemental lead in the ambient air. A

total of eight organizations submitted

written comments on the method and

two persons made comments at EPA's

February public hearing on the proposed air quality standard. Since proposal of the Federal reference method

for lead, EPA has completed additional testing of the method and added new information on the precision of

the extraction analysis procedure.

Two of the commenters recommended the addition of a nitric plus hydrochloric acid extraction procedure. The

extraction procedure of the propbsed

method contains only nitric acid.' Use

of a mixed acid procedure would

permit the analyst to quantitatively

extract more metals than just lead,

thereby allowing him to analyze the

same extract for more than one metal.

The analysis for lead would not be affected. EPA agrees that a mixed acid

extraction procedure should be added,

and the revised method contains a

mixed nitric-hydrochloric acid extraction procedure. -

- One commenter questioned the reliability of the air volume measured in

the sampling procedure because of differences between initial and final flow

rates caused by buildup of particulate

matter on the collecting filter. The

method of sampling specifies that initial and final flow rates must fall between 40 and 60 cubic feet per fflinute

Pnd variations within this range cause only a slight error. If- the flow rate

specification is not met, the 'sample

should be voided. For these reasons,

EPA believes the air volume measure- ment does not suffer unduly from inaccuracies.

A question was raised as to the

effect of variation in lead content

across the filter of the collected

sample on lead analysis, since the

method calls for analysis of only one strip or one-twelfth of the filter. Our

work has shown that strips taken from

different positions within the filter

can, on occasion, produce different

lead values, but the effect appears to

RULES AND REGULATIONS

be significant only when sampling

near a heavily traveled roadway. The

proposed method recommends analyzing additional strips, when sampling near a roadway, to minimize this error.

One commenter pointed out that the

proposed sampling procedure does not

collect gaseous (organic) lead com- pounds and recommended that EPA

consider requiring the use of a method

for monitoring gaseous lead.. As the

criteria document states, reported ambient levels of gaseous lead a;e very

low and EPA has determined that the

effort required to carry out-the difficult task of monitoring for ambient

gaseous lead is not justified in view of

the extremely low concentration.

It was pointed out in the preamble

to the proposed method that other

analytical prindiples would probably

be handled by provision for approval

of the' equivalent methods (40 CFR

Part 53) proposed elsewhere in this

FEDERAL REGISTER. Two organizations

submitted requests that alternate

methods (X-ray fluorescence and

anodic stripping voltametry) for lead

analysis be declared equivalent to the

reference method These requests will

be considered when the procedures for

determining equivalency are promulgated.

The final Federal reference method

is based on measuring the lead content

of suspended particulate matter on glass fiber filters using high volume

sampling. The lead is then extracted

from the particulate matter with

nitric acid facilitated by heat or by a -mixture of nitric acid and hydrochloric acid facilitated by ultrasonication.

Finally, the lead content is measured

by atomic absorption spectrometry.

The reference method specified for

lead measures the lead for a single

sampling period by extraction of a portion of a high-volume glass fiber

filter used to collect particulate

matter over a 24-hour period. Some

agencies may prefer to composite

filter strips from a number of sam- pling periods and extract ahd-analyze

it for lead. This procedure is acceptable provided the Agency shows that

the compositing procedure results in

the same average lead value as would

be obtained from averaging individual

values.

Dated: September 29, 1978.

DOUGLAS M. COSTLE,

Administrator.

REFERENCES

Angle, C. R. and M. S. McIntire. Environ--

mental controls and the decline of blood

lead. Arch. Environ. HIth. (in press.) 1977.

Azar, A., R. D. Snee, and K. Habibi. An

Epidemiologic Approach to Community Air

Lead Exposure Using Personal Air Samplers. Environmental Quality and Safety, Supplement Vol I-Lead 254-288 (1975). Barltrop, D., C. D. Strehlow, J. Thornton.

and J. S. Webb. Significance of high soil

concentrations for childhood lead burdens.

Environ. Hlth. Persp. Expt. Iss. 7:76-84,

1974.

Billick,. I. A. durran, and D. Shier. Presen.

tation to the U.S. EPA Lead Subcommittee

of the Science Advisory Board, Washington, D.C., October 7, 1977, Fine, P. R., C. W. Thomas, R. H. Suho R,

E. Cohnberg, and B. A. Flashner. Pedlatria

Blood Lead Levels A Study in 14 Illinois

Cities of Intermediate Population. JAMA

221:1475-1479, September 25, 1972.

Johanson. W. C, and . P. Luby. A Report on a Study to Determine the Blood Lead

Levels in Dallas Children. Dallas Health Dopartment, Dallas, Tex. 1972.

Johnson, D. E., J. B. Tillery, and R J. Provost. Levels of platinum, palladium and lead

in populations of Southern California. Envi- ron. Health Persp. 12:27-33, 1975.

Landrigan. P. J., S. H. Gehlbach, B. F. Ro

senblum, J. M. Shoults, et al. Epidemic Lead

Absorption Near an Ore Smelter, The role

of particulate lead. New England J. Med.

292:123-129, 1975.

Manton, W. I. Sources of Lead in Blood.

Akch. Environmental Health, 32:149-150,

1977. , Rabinowitz, M. B. Lead contamination of

the biosphere by human activity. A stable

isotope study, PhD Thesis, University of

California, Los Angeles, 1974, 120 pp. U.S.* Environmental Protection Agency. Air Quality Criteria for Lead Office of Research and Development, Washington, D.C, 20460. EPA-450/8-77-017, December 1977. von Lindern, I. and A. J. Yankel, Presentation to the Shoshone Heavy Metals Project

Committee by Idaho Department of Health

and Welfare, Boise, Idaho, September 4,

1975.

Yankel, A. J. and I. von Lindern. The

Silver Valley lead study. The relationship of

childhood lead poisoning and environmental

exposure. & Air Pollut. Cont. Ass., August 1977.

40 CFR Part 50 is amended by

adding a new § 50.12 and a new appendix G as follows:

§ 50.12 National primary and secondary

ambient air quality standards for lead.

National primary and secondary ambient air quality standards for lead

and its compounds, measured as elemental lead by a reference method

based on appendix G to this part, or

by an equivalent method, aie: 1.5 micrograms per cubic meter, maximum

arithmetic mean averaged over a calendar quarter.

(Sees. 109, 301(a4 Clean Air Act as amended

(42 U.S.C. 7409, 7601(a)).)

AXPENDIX G-RMassCE METHOD FOR T1E

DETERMINATION OF LFAD IN SUSPENDED PAn.

TicULATE MA=TR COLLEcTED PRoM AmaiENT Am

1. Principle and applicability. 1.1 Ambient air suspended particulate

matter is collected on a glass.fiber filter for

24 hours using a high volume air sampler, 1.2 Lead in the particulate matter is solubilized by extraction with nitric acid

(HNO.), facilitated by heat or by a mixture

FEDERAL REGISTER, ,VOL. 43, NO., 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46258 1978
RULES AND REGULATIONS

of ENO and hydrochloric acid (HCl) facilitated by ultrasonication.

1.3 The lead content of the sample is

analyzed by atomic absorption spectrometry

using an air-acetylene flame. the 283.3 or 217.6 nm lead absorption line, and the opti- mum instrumental-conditions recommended

by the manufacturer.

1.4 The ultrasonication extraction with

HNOJ/HC1 will -extract metals other than

lead from ambient particulate matter.

2. Rlange, sensitivity, and lower detectablie

Zimt. The values given below are typical of

the methods capabilities. Absolute values

will vary for individual situations depending on the type of instrument used, the lead

line, and operating conditions.

2.1 Range. -The typical range of the

method is 0.07 to 7.5 jg Pb/m 3 assuming an upper linear range of analysis of 15 jig/ml

and an air volume of 2,400 i

3

.

2.2 Sensitivity. Typical sensitivities for a. 1 percent change in absorption (0.0044 absorbance units) are 0.2 and 0.5 jig Pb/ml for

the 217.0 and 283.3 nm lines, respectively. 2.3 Lower detectable limit (LDL)-. A typical LDL is-0.07 jig Pb/m3!.The above value was calculated by doubling the between-laboratory standard deviation obtained for the

lowest measurable lead concentration in a collaborative test of the method.(15) An air

volume of 2,400 m3 was assumed. '

3. Interferences, Two types of interfer- ences are possible: chemical and light scattering.

3.1 Chemical. Reports on the absence (1,

2, 3, 4, 5) of chemical interferences far

outweigh those reporting their presence, (6)

therefore, no correction for chemical inter- . ferences is given here. If the analyst sus- pects that the sample- matrix Is causing a chemical interferencl, the Interference can be verified and correctedfor by carrying out

the analysis with and without the method

of standard additions.(7)

3.2 Light scattering. Nonatomi absorp- tion or light scattering, produced by high

concentrations of dissolved solids in the

sample, can produce a, significant interference, especially at low lead concentrations.

(2) The interference is greater at the 217.0

'um line than at the 283.3 nm line. No Interference was observed using the 283.3 nm line with a similar method.(1)

Light scattering interferences can, however, be corrected for instrumentally. Since

the dissolved solids can vary depending on the origin of the sample, the correction may be necessary,-especially when using the

217.0 nm line. Dual beam instruments with a continuum source give the most accurate

correction. A less accurate correctioncan be

obtained by using a nonabsorbing lead line

that is near the lead analytical line. Information on use of these correction techniques can be obtained from instrument

manufacturers' manuals. , If instrumental correction Is not feasible.

the interference can be eliminated by use of

the ammonium pyrrolidinecarbodithioatemethylisobutyl ketone, chelation-solvent ex- traction technique of sample preparation.(8)

4. Rrecision and bias.

4.1 The high-volume sampling procedure

used to collect ambient air particulate

matter has a between-laboratory relative

standard deviation of 3.7 percent over the

range 80 to 125 Ag/rm.(9) The combined ex- traction-analysis .procedure has an average

within-laboratory relative standard deviation of 5 to 6 percent over the range 1.5 to

15 jig Pb/ml, and an average between laboratory relative standard deviation of Ito 9

percent over the same range. These values

include use of either extraction procedure.

4.2 Single laboratory experiments -and

collaborative testing indicate that there Is no significant difference In lead recovery between the hot and ultrasonic extraction procedures.(l5)

S. Apparatu

5.1 Sampling.

5.1.1 High-volume sampler. Use and calibrate the sampler as described In reference

10.

5.2 Analysis,

5.21 Atomic absorption spectrophotometer. Equipped with lead hollow cathode or electrodeless discharge lamp.

5.2.1.1 Acetylene The grade recommended by the instrument manufacturer should

be used. Change cylinder when pressure

drops below 50-100 pslg.

5.2.1.2 Air. Filtered to remove partculate, oil, and water.

5.2.2 Glassware. Class A borosilicate

glassware should be used throughout the

analysis.

5.2.2.1 Beakers. 30 and 150 ml. graduated,

Pyrex.

5.2.2.2 Volumetric flasks. 100-ni].

5.2.2.3 Pipettes. To deliver 50. 30, 15. 8. 4.

2 .1 ml.

5.2.2.4 Cleaning. All glassware should be

scrupulously cleaned. The following procedure~s sugested. Wash with laboratory detergent, rinse, soak for 4 hours In 20 percent

(w/w) HNO,. rinse 3 times with distilled.

delonized water, and dry in a dust free manner.

5.2.3 Hot plate.

5.2.4. Ultrasonication water bath, un- heated. Commercially available laboratory

ultrasonic cleaning baths of 450 watts or higher "cleaning power," Le., actual ultrasonic power output to the bath have been

found satisfactory.

5.2.5 Template. To aid In sectioning the

glass-fiber filter. See figure 1 for dimensions,

5.2.6 Pilzz cutter. Thin wheel. Thickness

<lmm.

5.2-7 Watch glass.

5.2.8 Polyethylene bottles. For storage of

samples. Linear polyethylene gives better

storage stability than other polyethylenes

and is preferred.

5.29 Paraflim "W".0 American Can Co., Marathon Products, Nennah. Wis., or equiv- alent.

6. Reagents.

6.1 Sampling.

6.11 Glass fiber filters. The specifica- tions given below are Intended to aid the user In obtaining high quality filters with

reproducible properties. These specifications have been met by EPA contractors.

6.1.L1 Lead content. The absolute lead

content of filters is not critical, but low

values are, of course, desirable. EPA typically obtains filters with a lead content of <75

j9g/fllter.

It is Important that the variation In lead

content from filter to fter, within a given

batch, be small

6.1.1.2 Testing. . 6.1.1.2.1 For large batches of filters

(>500 filters) select at random 20 to 30 flters from a given batch. For small batches

(<500 filters) a lesser number of filters may

be taken. Cut one 2/x8' strip from each

*Mention of commercial products does

not Imply endorsement by the US. Environmental Protection Agency.

filter anywhere in the filter. Analyze all

strips, separately, according to the directions in sections 7 and 8-

6.1.1.2.2 Calculate the total lead in each

filter as

F Pbml x100 MI X 12 strips Fb= pg Pb/mI x 100T~ r l 2 fite

bstrp - f!ilterwhere:

Pb-Amount of lead per 72 square inches of

filter, jig.

6.1.1.2.3 Calculate the mean. F., of the

values and the relative standard deviation

(standard deviation/mean x 100. if the relative standard deviation is high enough so

that, In the analysts opinion, subtraction of

F. (section 10.3) may result in a significant

error In the pg Pb/m3- the batch should be

rejected.

6.1.124 For acceptable batches, use the

value of Pb to correct all lead analyses (section 10.3) of particulate matter collected

using that batch of flters. If the analyses

are below the DL (section 2.3) no correc- tion is necessary.

6.2 Anaysls.

6=1 Concentrated (15.6 A0 HNO ACS

reagent grade HNO and commercially avalable redistilled HNO. has found to have suffcliently low lead concentrations.

6.2.2 Concentrated (IL7 M) HCL ACS

reagent grade.

6..3 Distilled-deionzed water. D.I.

water).

6.4 3 At HNO. This solutlon is used in

the hot extraction procedure. To prepare,

add 192 ml of concentrated HNO. to D.

water in a I ! volumetric fssk. Shake well

cool and dilute to volume with DI. water./

Caution: Nitric acid fumes are toxic. -Pre

pare n a well ventilated fume hood.

6.25 0.45 M HNO. This solution is used

as the matrix for calibration standards

when using the hot extraction procedure.

To prepare, add 29 ml of concentrated

ENO. to D.L water In a 1 1 volumetric flask.

Shake well, cool, and dilute to volume with

D.L water.

6a6 2.6 A HNOb+0 to 0.9 A HCL This

solution Is used in the ultrasonic extraction

procedure. The concentration of HCI can be

varied from 0 to 0.9 .. Directions are given

for preparation of a 2.6 Afr HO0.9 M HCI

solution. Place 167 ml of concentrated ENO.

into a 11 volumetric flask and add 77 ml of

concentrated HCI. Stir 4 to 6 hours dilute

to nearly 1 I with D.L water cool to room temperature, and dilute to 1 L

6±9-7 OAOMHNO +XMrHCLThissolution Is used as the matrix for calibration

standards when using the ultrasonic extraction procedure. To prepare, add 26 ml of

concentrated HNO,, plus the ml of HC1 re- quired, to a 1 1 volumetric flask. Dilute to

nearly 1 1 with D.I water cool to room temperature and dilute to 1 L The amount of

HC1 required can be determined from the

following equatio

Y 77m1 x 0.15x

0.9 M

FEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, -OCTOBER 5, 1978

46259.

HeinOnline -- 43 Fed. Reg. 46259 1978
46260

where:

y - ml of concentrated HCI required.

x - molarity of HCI in 6.2.6.

0.15 = dilution factor in 7.2.2.

6.2.8 Lead nitrate, Pb(NO.).. ACS reagent

grade, purity 99.0 percent. Heat'for 4 hours

at 120" C and cool in a desiccator.

6.3 Calibration standards..

6.3.1 Master standard, 1000 pg Pb/ml in

HNO,. Dissolve 1.598 g of Pb(NO.). in.0.45 M

HNO, contained in a 1 1 volumetric flask

and dilute to volume with 0.45 M HNO .

6.3.2 Master standard, .1000 pg Pb/ml in

HNO,/HCl. Prepare as in 6.3.1 except use the, HNO./HCI solution in 6.2.7.

Store standards in a polyethylene bottle.

Commercially availablecertified lead standard solutions may also be used.

7. Procedure.

7.1 Sampling. Collect samples for 24

hours using the procedure described in reference 10 with glass.fiber fifters meeting the

specifications in 6.1.1. Transport collected

samples to the laboratory taking care to.

minimize contamination and loss of

sample. (17).

7.2 Sample preparation.

7.2.1 Hot extraction procedure.

7.2.1.1 Cut a %" x 8" strip from the exposed filter using a template and a pizza

cutter as described in figures land 2 Other

cutting procedures may be used.

Lead in ambient particulate matter collected on glass fiber filters has been shown

to be uniformly distributed across-the filter

(1, 3, 11) suggesting that the position of the

strip Is unimportant. However, another

study (12) has shown. that when sampling' near a road-way lead is not uniformly distributed across the filter. The nonuniformity has been attributed to large variations

in particle size. (16) Therefore, when sam- pling near a road-way, additional strips at

different positions within the filter should

be analyzed.

7.2.1.2 Fold the strip in half twice and"

place in a 150-ml beaker. Add 15 ml of 3 M

HNO, to cover the sample. The acid should

completely cover the sample. Cover the

beaker with a watch glass.

7.2.1.3 Place beaker on the hot-plate,

contained in a fume hood, and boll gently

for 30 min. Do not let the sample evaporate

to dryness. Caution: Nitric acid fumes are

toxic.

7.2.1.4 Remove beaker from hot plate

and cool to near room temperature.

7.2.1.5 Quantitatively ' transfer the

sample as follows:

7.2.1.5.1 Rinse watch glass and sides of

b eaker with D.I. water.

7.2.1.5.2 Decant extract and rinsings into

a 100-ml volumetric flask.

7.2.1.5.3 Add D.I. water to 40 ml mark on beaker, cover with watch glass, and set aside

for a minimum of 30 minutes, This Is a critical step _and cannot be omitted since it

allows the HNO, trapped in the filter to diffuse into the'rinse water.

7.2.1.5.4 Decant the water from the filter

into the volumetric flask.

7.2.1.5.5 Rinse filter and beaker twice

with D.f. water and add rinsings to volumetric flask until total volumeois 80 to 85 ml.

7.2.1.5.6 Stopper flask and shake vigorously. Set aside for approximately 5 minutes or until foam has dissipated.

7.2.1.5.7 Bring solution to volume with

D.I. water. Mix thoroughly.

RULES AND REGULATIONS

7.2.1.5.8 Allow solution to settle for one. hour before proceeding with analysis. 1 7.2.1.5.9 If sample is to be stored for subsequent analysis, transfer to a linear lpolyethylene bottle.

7.2.2 Ultrasonic extraction procedure.

7.2.2.1 Cut a Y" x 8" strip from the ex- posed filter as described in section 7.2.1.1.

7.2.2.2 Fold the strip in half twice and

place in a 30 ml beaker. Add 15 ml of the

HNO./HCl solution in 6.2.6. The acid should

completely cover the sample,. Cover the

beaker with parafilm.

Th'e parafilm should be placed over the

beaker such that none of the paraflm Is in

contact with water in the ultrasonic- bath.

Otherwise, rinsing of the parafilm (section

7.2.2.4.1) may contaminate the sample.

7.2.2.3 Place the beaker in the ultrasoni:

cation bath and operate for 30 minutes.

7.2.2.4 Quantitatively transfer the

sample as follows:

7.2.2.4.1 Rinse parafilm and sides of

beaker with D.I. water.

7.2.2.4.2 Decant extract and rinsings into a 100 ml volumetric flask.

7.2.2.4.3 Add 20 ml D.I. water to cover the filter strip, cover with parafilm, and set

aside for a minimum of 30 minutes. This is a critical step and cannot be omitted. The

sample is then processed as in sections

7.2.1.5.4 through 7.2.1.5.9.

NoTE.-Samples prepared by the hqt ex- traction procedure are now in 0.45 M HNO,.

Samples prepared by the ultrasonication

procedure are in 0.40 M HNO + X M HCI.

8. Analysis. -

8.1 Set the wavelength of the monochromator at 283.3 or 217.0 nm. Set or align

other instrumental operating conditions as recommended by the manufacturer.

8.2 The sample can be.analyzed directly

from the volumetric flask, or an appropriate

amount of sample decanted into a sample

analysis tube. In either case, care should be

taken not to disturb the settled solids.

8.3 Aspirate samples, calibration standards and blanks (section 9.2) into the flame

and- record the equilibrium absorbance.

8.4 Determine the lead concentration in

pg Pb/m, from the calibration curve, sec- tion 9.3.

8.5 Samples that exceed the linear calibration range should be diluted with acid of

the same concentration as the calibration

standards and reanalyzed.

9. Calibration.

9.1 Working standard, 20 pg Pb/mi. Prepared by diluting 2.0 ml of the master

standard (6.3.1 if the hot acid extraction

was usedor 6.3.2 if the ultrasonic extraction

procedure was used) to 100 ml with acid of

the same concentration as used in preparing

the master standard.

9.2 Calibration standards. Prepare daily

by diluting the working standard, with the same acid matrix, as indicated below. "Other

lead concentrations may be used.

Volume of 20 Final volume. Concentration

pg/ml working ml pg Pb/ml

standard, ml

0 100 0

1.0 200 0.1

2.0 200 0.2

2.0 100 0.4

4.0 100 0.8

8.0 100 1.6 15.0 100 3.0,

30.0 100 6.0

50.0 100 10.0

100.0 . 100 20.0

9.3 Preparation of calibration curve,

Since the working range of analysis will

vary depending on which le'ad line is used

and the type of instrument, no one set of

Instructions for preparation of a calibration curve can be given. Select standards .(plus

the reagent blank), in the same acid concen- tration as the samples, to cover the linear

absorption range indicated by the instrument manufacturer. Measure the absor.

bance of the blank and standards as In section 8.0 Repeat until good agreementIs obtained between replicates. Plot absorbance

(y-axis) versus concentration in pg Pb/ml

(x-axis). Draw (or compute) a straight line

through the linear portion of the curve. Do

not force the calibration curve through zero. Other calibration procedures may be

used.

To determine stability of the calibration

curve, remeasure-alternately-one of the

following calibration standards for every

10th sample analyzed: concentration ;5 1lpg

pb/!nl; copcentration 9 10 pg Pb/mi, If

either standard deviates by more than 5 percent from the value predicted by the calibration curve, recalibrate and repeat the

previous 10 analyses.

10. Calculation.

10.1 Measured air volume. Calculate the

n easured air volume as

Qi + Qf

Vm = 2 xT

where:

V.,=Air volume sampled (uncorrected). m3

.

O1=Initia air flow rate, m3/min.

Qt=Final air flow rate, m3/min.

T=Sampling time, min.

The flow rates QL and Q, should be cor- rected to the temperature and pressure con- ditions existing at the time of orifice call.

bration as directed in addendum B of refer- ence 10, before calculation V..

10.2 Air volume at STP. The measured

air volume is corrected to reference 'conditions of 760 mm Hg and 25" C as follows.

The units are standard cubic meters, sm3.

VSTP = V P2 xT 1

Vnp=Sample volume, sm3, at 760 um Hg

and 298' K,

V,=Measured volumd from 10.1.

P,=Atmosbherlc pressure at time of orifice

calibration, nun Hg.

P,=760 mnm Hg.

T =Atmospheric temperature at time of orifice calibration, *K.

T,=298" K.

- 10.3 'Lead concentration. Calculate lead

concentration in the air sample.

(ug Pb/ml x 100 ml/stri x 12 strps/fliter) - r C- b

FEDERAL REGISTER, VOL 43,-NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46260 1978
where:

C=Concentration, jg Pb/sm'.

jg Pb/ml=Lead concentration determined

from section 8.

100 m /strip=Total sample volume.

12 strips/filter=Useable filter area, 7" X 9"/

Exposed area of one strip, T" X 7".

Fb=Lead concentration of blank filter, A±g,

from section 6.1.1.2.3.

Vs-=Air volume from 10.2.

11. Quality control

%" x 8" glass fiber filter strips containing 80 to 2000 pg Pb/strlp (as lead salts) and

blank strips with zero Pb content should be

used to determine if the method-as being

used-has any bias. Quality control charts

should be established to monitor differences

between measured and true values. The frequency of such checks will depend on the

local quality control program.

To minimize the possibility of generating

unreliable data, the user should follow practices established for assuring the quality of

air pollution data, (13) and take part in

.EPA's semiannual audit program for leadanalyses.

12. Trouble shooting.

1. Duiring extraction of lead by the hot ex- traction procedure, it is important to keep

the sample covered so that corrosion produbts-formed on fume hood surfaces which

may contain lead-are not deposited In the

extract.

2. The sample acid concentration should

minimize' corrosion of the nebulizer. Howev'-

er, different nebulizers may require jower

acid concentrations. Lower concentrations can be used provided samples and standards

have the same acid concentration.

3. Ashing 6f particulate samples has been

found, by EPA and contractor laboratories,

to be unnecessary in lead analyses by atomic

RULES AND REGULATIONS

absorption. Therefore, this step was omitted

from the method.

4. Filtration of extracted samples, to remove particulate matter, was specifically

excluded from sample preparation, because some. analysts have observed losses of lead

due to filtration.

5. If suspended solids should clog the ne- bulizer during analysis of samples, centrifuge the sample to remove the solids.

13. Authority.

(Sees. 109 and 301(a). Clean Air Act as amended, (42 U.S.C. 7409. 7601(a)).)

14. References.

1. Scott, D. R. et al. "Atomic Absorption

and Optical Emission Analysis of NASN Atmospheric Particulate Samples for Lead."

Envir. ScL and Tcch., 10, 877-880 (1976).,

2. Skogerboe R. K. et al. "Monitoring for

Lead in the Environment" pp. 57-66. Department of Chemistry, Colorado State University, Fort Collins, Colo. 80523. Submitted

to National Science Foundation for publications, 1976.

3. Zdrojewskl, A. et al "The Accurate

Measurement of Lead In Airborne Particulates." Inter. . Envfron. Anal Chem., 2, 63-

77 (1972).

4. Slavin, W., "Atomic Absorption Spectroscopy." Published by Interscence Company, New York. N.Y. (1968).

5. Kirkbright, G. F., and Sargent. M..

"Atomic Absorption and Fluorescence Spectroscopy." Published by Academic Press.

New York. N.Y. 1974.

6. Burnham, C. D. et at. "Determination

of Lead in Airborne Particulates In Chicago

and Cook County, IlL by Atomic Absorption

Spectroscopy." Envir. SdL and Tech., 3, 472-

475 (1969),

7. "Proposed Recommended Practices for

Atomic Absorption Spectrometry." AS.TM

46261

Book of Standard% part 30. pp. 1596-1608

(July 1973).

8. Koirttyohann, S. R. and Wen. J. W.

"Critical Study of the APCD-MIBK Extraction System for Atomic Absorption." AzaL

Chem., 45, 1986-1989 (1973).

9. Collaborative Study of Reference

Method for tMe Determination of Suspended

Particulates in the Atmosphere (High Volume Method). Obtainable from National

Technical Information Service, Department

of Commerce, Port Royal Road, Springfield, Va. 22151, as PB-205-891.

10. "Reference Method for the Determination of Suspended Particulates In the Atmosphere (High Volume Method)." Code of

Federal Regulations, Title 40, Part 50, Appendix B. pp. 12-16 (July 1, 1975).

11. Dubois. L,, et al., "The Metal Content

of Urban Air." JAPCA, 16, 77-78 (1966).

12. EPA Report No. 600/4-77-034. June

1977. "Los Angeles Catalyst Study Symposlum." Page 223.

13. Quality Assurance Handbook for Air

Pollution Measurement System. Volume IPrinciple& EPA-600/9-76-005, March 1976.

14. Thompson, R. J. et al, "Analysis of Selected Elements In Atmospheric Particulate

Matter by Atomic Absorption." Atomic Absorption Newsletter. 9, No. 3. May-June

1970.

15. To be published. EPA, QAB, EMSL,

RTP, N.C. 27711

16. Hlrschler, D. A. et at, "Particulate

Lead Compounds in Automobile Exhaust

Gas." Industrial and Engineering Chemistry, 49, 1131-1142 (1957). -

17. Quality Assurance Handbook for Air

Pollution Measurement Systems. Volume

lI-Ambfent Air Specific Methods. EPA-600/

4-77/027a May 1977.

[FR Doc. 78-28050 Filed 10-4-78; 8:45 am]

FEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

HeinOnline -- 43 Fed. Reg. 46261 1978