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Citation: 43 Fed. Reg. 46246 1978

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### 46246


### [6560-611

Title'40-Protectionof Environment.

CHAPTER I-ENVIRONMENTAL PROTECTION AGENCY

SUBCHAPTER C-AIR PROGRAMS

[FRL937-5]



### 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 ordertolist lead as-acriteriaipollutant for the development of an ambient standard, andthe Agency'sissuance 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 acalendar 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 beregarded as a groupwithin 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/dlAre associated with the impairment of heme synthesis in cells indicatedby elevated erythrocyte protoporphyrin '(EP), which EPAxegards Ls adverse to the health of. chronically exposed children. There are anumber of-other-adverse health effects associated With blood lead levels above 30 gg Pb/dl, in children aswell as in the general pop- ulation, including-the possibility that

nervous system damage may occur in children even without overt-symptoms ofleadpoisoning. 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 ofthe standard by no later than October of 1982. EPA's final reg- ulations for the development of State -RULES AND REGULATIONS

implementation plans appear else

### where in thisFEDERAL 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 =standardisaVailable forpublic 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 publishedii appendix G to thispromulga

### tion. This FEDERAL REGISTER 

### also cofltains proposed regulations under 40 CFR Parts '51 and 53 for equivalent lead air monitoring methods, final rules forthe development ofState implementation ' plans promulgated under 40 CFRPart 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 LeadAir Enissions were issued af'the -time of-proposal. The Control Tech-

- niques Document is available uponre-

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 oflead 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 ofno- lead gasoline for catalyst-equipped

cars. EPA also intended to control emissions from certain categories of industrial point sources under section ill ofthe Clean AirAct.

In 1975, the Natural Resources Defense Council (NRDC) and others brought suit against EPA to list lead under section 108 ofthe Clean Air Act

as a pollutant for which air quality criteria wouldbe developed and anation. 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 Federalreference 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 SIPregulations, Additional comments on these matters

were provided to EPA at apublic hearing held onFebruary 15-16, 1978.

LEGISLATIvE REQUIREMENTS For NATIONAL AMBIENT AIR QUALITY STANDARDS
Sections 108 and 109 of the Clean AirAct govern the development ofna- tional ambient air quality standards. Section 108 Instructs EPA to document the scientific basI9 forthe standard:

Section 108(a)(2). The Administrator shall issue airquality criteria foran airpollutant within 12months after hehasincluded 

### 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 1978ambient air,invarying quantities.The criteriafor an airpollutant;to theextentpracti- cable,shallinclude 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 orwelfare ofsuch airpollutant;

(B) The types of air pollutants which, when present in theatmosphere, may interact with such pollutant to,produce an ad-

verse effect onpublichealth orwelfare; and

(C) Any known or anticipated adverse effects onwelfare.

Section 109 addresses the actual settingofthe 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 aspromulgated. .

(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 inthejudgment ofthe Administrator, based

on such criteria, is requisite to protect the publicwelfare fromany knownoranticipat- ed adverse effects associated with the pres- ence of such air pollutant in the ambient
air. Such secondary standards may be revisedinthe samemanner aspromulgated.

In order to conform to the requirements of section 109, EPA has based the level ofthe 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 toplace 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 ofreported health effects, the probability that such effects may occur, and uncertainties as to the full biological significance of exposure to lead. IComments resulting from external review of the air quality criteria and the proposed- standard highlight disagreements on anumber ofareas 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 ofthe Act requiring timely promulgation ofthe standard, andrequirements 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 GENERALFmDinGs F!Rou AmQUALITY CRITERIA FORLvw Following thelisting oflead 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 ofthe 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 forlead.

1. There are multiple sources oflead 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 andsoil.

3. There is significant individual variability in response to lead expo-
sure. Even within a particular population, individual response to lead expo-
suremay varywidely from the average response for the same group. Certain subgroups within the general population are more susceptible to the effects oflead 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, neuro

### 46247
logical damage ordeath asblood leads approach and exceed 80 to 100pgPb/ dl in children down to the inhibition of an enzymes system as low as 10pg 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'sjudgment that themaximum 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 of3.0 pgPb/dlwas estimated tobethe 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 shouldbe 1.5pg/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 thatthe existing regulations forthe phase-down ofleadin 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 exhaustisthe 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 standardin thevicinity ofnonferrous 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 ofState plans to-implement thestandard, 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 theStateplans.

Also, EPA is encouraging affected firms andState 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

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### 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 examined, while at the same time 'assuring protection from clear risks to the public health.

SuMARY.

### oF CoMNTsRECEIVED During the comment period from flecember 14, 1977, to March 17, 1978, and at thepublic meeting onFebruary 15-16, 1978, -EPA received 95 written and oral comments addressing theproposed 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 ttgPb/m, calendar quarter average, as the appropriate level for the standard.

Comments,Received.OpposingtheProposed

standard of 1.5 lig/m' Calendar,Month AverageasExcessivelyStringent

Company Op- Enposed ' dorsed2

AmaxLead &Zinc,

. X

, X American MiningCongress

......... x M AmericanPetroleumInstitute

. X ASARCO

............................................ X AssociatedOctel Co., Ltd X X Battery Councl InternationaL....

- - X Bethlehen.Steel Corp

........ .. . BunkerHill Co.

............... *

............. X X C&D_ Batterles vslon-o.......... x 7X E. Ldu Pont de Nemours &Co.,

Inc

.............. . ................ .. x X ESALaboratories, Inc

..................... X X Ethyl Corp

.................................. X x General Battery,Cor rp........... X X GeneralMotors.Corp-............... Getty Refining&Marketing Co X HECLA MiningCo

........................... x Houston:Chemlcal

.................. .X N HuntOil C o. N Kerr-McKee Corp

.......................................... LeadIndustriesAssociation

........... x X 'Nalco'Chemical :X X N LIndustries,'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 UnitedMachinery Group.,

.................. VulcanMaterials Co

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

'1.5 jg/rm, calendarmonth.

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

Sueny: Forty-five comments received from 29 corporations or their representatives; 25 of the29 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 otheraveraging 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 CenterPublic Interest Campaign University of Connecticut School of Med,

cine

- Comments suppoiting the level of

theproposed 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

-STATEANDLOCAL 'AGENCIES

California Department ofHealth Wassachusetts Department ofPublic'Health New York State Department of ,Environ-

- mental Conservation New York City Department ofEnvironmentalProtection Tennessee Department of-Public Health 'Wisconsin 'Department of 'Natural Re-

sources

FEDERAL AGENCIES

Center -forDisease 'Control, Public Health

Service Departmenlt ofTransportation -FoodandDrugAdministration Occupational Safety and Health Administratiofi-'

PUBrc INTEREST'GROUPS AND THEMEDICAL

"Comritte-on Environmental Hazards,

American Academy ofPediatrics D.C. Committee forLead Elimination inthe

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, -EPAhas received- numerous comments and correspondence

on theproposed standard afterthe official end of the comment period. Though'EPA-does nothavea legal obligation to review these documents, -it has, in the interest of fostering full -publicparticipation in the rulemaking process, reviewedthese comments and correspondence as time permitted. As with all other documents considered

_or examined by EPA as part ofits decision process, these documents have been placed in the public .docket and have become part of the administrative record ofthisdecision. The comments received by EPA did ,notchallenge three-aspects oftheproposed standard:

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

2. The selection ofyoung children as

a population particularly at risk to lead exposure.

3.The attribution of 12 1Ag Pb/dlout of the target mean population blood -lead level of 15 ig Pb/dl to nonair

sources oflead for thepurposes of settingthe 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 bloodlead 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 oflead In the blood to lead in the air.

5. The statistical form and averaging periodforthe standard.

6. The appropriate marginof safety. 7. The limitation of the standard to the respirable fraction oftotal air lead particles.

8. The economicInpact ofthe 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 andwthe provision for publicparticipation.

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 ERYTHROCYTEPROTOPORPHYIIN ELEVATION

Ten commenters disagreed with -EPA'sconclusion -that 'theimpairment ofheme 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. 'EPelevation, -while indicating a change inheme synthesis, does not 

### in. "-dicate an insufficient production of heme, orhemoglobin.

3. 'EP elevation and the alteration Qf heme synthesis doesnot imply impair-

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

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### RULES AND REGULATIONS

ment of other mitochondrial tions.

4-EP elevation isnotassociated impairment of other heme pro particularly cytochrome P-450.

5. Elevated EP may be cause conditions other than exposur lead,particularly irondeficiency.

Five commenters agreed with I conclusions about the health si

cance ofelevated EP citing the ft ing arguments:

1.The interference oflead in a damental cellular metabolic fun to the extent that there is acet tion ofa substrate is physiologic pairment, even without the pre ofclinical evidence ofdisease.

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 atenhancec
tolead 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 forhematopc

AGENCY RESPONSE EPA agrees with the commenI ceived that the-initial elevation c
as a result of exposure to lead, indicatingan impairment ofhem( thesis,maynotbe 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 leaddose.

-Thehematological effects described

are the eariesf physiological impair encountered as afunction of ncreasin

exposures as indexed by blood lead tions, as such, those effects may bec ered to represent critical effects ofle, posure. Although itmaybeargued titain of the initial hematological ( (such as ALAD inhibition) constitute tively mild, nondebilitating symptoi low blood lead levels, they nevert signal theonset ofsteadily intensifyt

verse effects as blood lead elivatio:

crease- Eventually. the hematologic fects reach such magnitude that they clear-cut medical .significance as Indi ofundue leadexposure.

Thefact 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 ofa child t adverse effects oflead 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 havebeen teins. extensively studied in part because of the ease with which this tissue maybe d by obtained, other cellular metabolic-sys-

re to tems utilizing heme are less well un- derstood.EPA doesnot have sufficient PA's information to conclude that impairgnifi- ment of heme synthesis In other tisllow- sues is not of concern untilblood 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 otherdose-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 systemicfunction ofwhich

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

that inneural tLmue. CP. 13-5.)
Lffect In summary, the criteria document patic states: pro- Elevation Inprotoporphyrinis considered )iesIS. notonly to be a biological Indicator of ImpairedInItochondrlal function of erythrold tissuebit also an Indicator of accumulation ofsubstrate forthe enzyme ferrochelatase. It therefore has the same pathophysologi- ofEP 6al meaning as increased urinary 8-ALA while (vide supra). For these reasons, accumulaesyn- tion ofprotoporphyrln hasbeen takentoIn-

orbe dicatephysiologieal Impairment Inhumans. !cline and this clinical consensus Is expressed In iteria the 1975 Statement of the Center for Distthis ease Control (CDC), USPHS. The criterion usedby CDCto Indicate an effectofleadon ssive- heme functionIs anFEP level of 60pg/dl In the presence ofa blood lead level above 30 above pg/dlwhole blood. rments More recent Information relating to
glead thresholdofleadeffects Indicates that PEP eleva- levelsbegin toincrease atabloodleadvalue onsld- of 15 to 20 pg Pb/dl blood In children and adex- women and, at asomewhat higher value. 20 itcer- to 25pgPb/dlblood, Inadultmen. (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 onsetor a mild ex-
ns in- perience of this condition may be tolal ef- erated by an individual, as with other
areof 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 ofanemia in chitth 

### an dren may occur at bloodlead levels of !re is 40 pg/d. EPAhas adopted 30pg Pb/dl defi- as amaximum safeblood leadlevel for the individual children. Ly Mh THE BLOOD LEAD THRESHOLD FOR ELEVATSthe E ERYTHROCYTEPROTOPORPHYRIN

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.

ahigher thresholdincluded:



### 1. The threshold accepted byEPAis 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 higherthreshold.

3. The study in"question excluded dataon children withblo6dleadIevqls inexcess of30 pg/d.

4. Other investigators have reported higher thresholds.

Comments insupport ofthe 15pg/dl thresholdmaintained:

1. It Isproper to exclude values con- sidered abnormal if the intent of the analysis is to determine an unbiased effectthreshold.

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 segmentedline 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 PbldLand forthis

reason considered changing its judgments as to the maximum safe blood lead level fora population ofchildren. 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 bebelow 30pg Pb/dL At 16.7 pg Pb this percentage falls to 98.7. EPA regards the number ofchildren predicted tobebelow 30pg 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 bloodlead.

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 toimply thatthe air standard was notnecessary to protectpublic health.

AGENCY RESPONSE

EPA aclmowledges the variability of the impact of exposure to air lead on thepotential foradverse 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 

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routes through which human expo- sure occurs. It is for this reason that the Agency has accepted the concept that only aportion ofthe 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. Takinginto 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 forDisease Control, the criteria document reports:

It was concluded that the primary factor associated with elevated bloodlead levels in the children was ingestion or inhalation of dust containinglead. Dataon 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 ofthe 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 ofleadinsoil (ppm). 3. Age (years). 4. Cleanliness of the home (subjective evaluation.coded 0, 1, and 2, with 2'signify- ingdirtiest).

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 thatitwas 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 oflead 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 aboutthe extent to which air quality observations accurately re- flect actual exposure. From the Azar data, the relationship oflead 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 ifnot 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 asmelter, 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 alsosome 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 thelognormal 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 0.41jg/M 3in 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 ofthe averaging period is the health significance of possible elevations of air lead ,above 1.5 jg/m3 which could be sustained without violation ofthe average of 1.5 pg/m3

. In the proposed standard, EPA chose a monthly averaging period on the basis ofa study showing anadjustment period ofblood lead level with a change ofexposure (Griffin et al.). Be-

cause of the scientific and technical difficulties of the monthly standard, EPAhas 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 Isbased on the following points:

(1) From actual ambient measure- ments, the distribution of air lead levelsis such thatwhere the quarterly standard is achieved, there Is little possibility that there could be sus- tained periods greatly above the aver- agevalue.

(2) While It is difficult to relate the extent to which a monitoring network actuallyrepresents the exposure situation foryoung 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 periodreported bythe 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 ofa short-term period of expo-
sureto elevated air lead.

(4) Direct exposure to air is only one of several routes of total exposure. Thislessens the Impact ofa change in air lead onblood leid levels.

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

HeinOnline -- 43 Fed. Reg. 46250 1978On 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 ofthe standard.

THEAPPROPRIATE 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 viewthat the critical health effect,,impaired heme synthesis, was not of health significance

oron theview 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 generalpopulation ofyoung children.

AGENCY RESPONSE

EPA does not agree thatthe impairment of heme synthesis is a physiological response to lead exposure that is without health significance. While EPA does not fid-that this impairment isnecessarily seriousto.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 pgPb/dl this effect has progressed
to the extent that it shouldbe regardedas anadverse health effect.

In determining the final ambient air standard' for lead, EPA has used margin ofsafety considerations princlpally in establishing a maximum safe bloodleadlevelforindividual children at 30jgPb/dland in determining the -percentage of children to be placed below this maximum level, about 99.5 percent. Usini thesefactors, resultsin

a target geometric niean population bloodlead of15pgPbfdl.

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 attheprecautionary extreme ofthe range ofdataavailable to theAgency. In the case ofthe geometric standard deviation (GSD), studies reviewed in the criteria document showed a range of 1.3 to 1.5. A standard-basedon 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 therelationship between air lead and blood 

### RULES AND REGULATIONS

leadto be 1:2,the Agency used anepidemiological study of children near a smelter, Yankel etal, whereresponse ofbloodleadto airlead 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 concernedthat typical levels for this component may be muchgreater, and that regulatory actionsby other public healthpiograms may be necessary to achieve a 12 pg level.

Because of the variability between individuals in apopulation experlencing-agivenleveloflead 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 largeor onthe otherhand thattheair standard can protect everyone from elevated bloodlead levels.

THEIMPORTANCE OFTHE RESPIRABLE
FRACTION OFTOTALAMLEAD LEVEL


### The Agency received a number of
comments expressingconcern that,because only a fraction of airborne particulate matter is respirabl% an air standard based on total air leadisunnecessarily stringent.

AGENCY RESPONSE 

### EPA agrees that some lead particles

aretoo small ortoo large to be deposited in the respiratory system. EPA
cannot conclude, however, that particles outside ofthe respirable range do
not represent an exposure hazard. A significant component of exposure can beingestion ofmaterials contaminated by deposition of lead from the air. In addition to the indirect route ofingestion 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 airstandard.
ECONOMICIMPACE OFTHEPROPOSED

STANDARD 

### Anumber of commenters were crtical of the Agency's economic impact assessment, and argued that the forecast underestimated the severity of the economic impactto certainleadIndustries. 

### 46251

AGENCY RESPONSE The comments critical of the draft impact statement did not include data whichwould allowEPAto confirm the possibility of more severe economic Impacts on certain source categories including primary and secondary lead smelters which couldhave difficulty in limiting emissions sufficiently to

assure attaining the standard in their immediate vicinity. Under the Clean AirAct, the primary responsibility for implementing thestandard isassigned
to the States and each State is required to submit a plan to EPA demonstrating how attainment is to be achieved. The actual economfimpacts ofImplementation aredifficult toestimate atthis time since,following promulgation, States wil have 9 months
to develop and submit these plans to EPA. The plans must demonstrate attainment as soon aspracticable, butno later than 3 years following the date of plan approval. However, under certain circumstances, Statesmayrequest; up to a 2-year extension ofthis deadline. Other sections of the Clean Air Act maybe used with theAdministrator's discretion tograntfurther extensions of compliance deadlines for impacted industrial facilities.

EPA cannot.at this time accurately predict the impact of this standard, butwith the timetable in theAct, sees

noreason to expect imminent closure ofany facility. The Agency is committed to developing accurate data for specificplants in cooperation withthe Industry and State agenciesin 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 ofthepublichealth.

EPA believes that the economic Impact asessmentis a reasonable forecast ofthe economic consequences of implementation ofthe 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.

THEFEDERAL REFERENCEMETZOD FOR. MONITORING LEAD AIR QUALITY
A summary of conments and the Agency's disposition 

### isincluded in the preamble to the final method published elsewhere In this FEDERAL.EGTHE ADMINISTRATIVE PROCEDURES EMPLOYED BY EPAIN THEDEVELOPM[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 thepost-proposal public hearing on the proposed standard and implementation regulations.EPA also received arequest topostpone thepublic hearing and to extend the comment period, citing theneed 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 therequestfor 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 ofthe 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 forthe final standard:

(1) EPA is making a distinction between the bloodJead 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 itis regarded as adverse to health.

(2) EPA is making a distinction between estimating a maximum safe blood leadlevel 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 ofstandard setting.

DERIVATION OF THENUMERICAL LEVEL OF THEFINAL STANDARD ,EPA's objective in setting the level ofthe 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 judgmentin fourkey areas:

(1) Determining the "sensitive population" as that group vithinthe 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 is30 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 Statesbelow 30jgPb/dl

.

(3) Attributing the contribution to blood lead from nonair pollution

sources. EPA concludes thaf 12 jIgPb/ 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 achievingthe standard to 3 jugPb/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 shouldbe 1.5 1zgFPb/m3.

Each ofthese 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 risksubgroups has, however, influenced EPA's determination of the percentage of the population of children (99.5 percent) to be maintained below30jigPb/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 oflead, and,transplacental transfer of lead may affect the prenatal development ofthe 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.

THEMAXIMuM 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, forexample thelevel ofzinc protoporphyrin (ZPP), but most health studies reported in the criteria document utilize blood lead levels as indications of the mobile body burden oflead. The criteria document reports the following table of effect thresholds,forchildren withincreasing-blood leadlevels.
SUMMARY OFLOWEST OBSERV, MEf ECT LEVELS IN YOUNG CHILIREN
pvPb/dl
8-ALAD inhibition

..................... ............. 10 Erythrocyteprotoporphyrinelevation 15-20 Increasedurinary8-ALA excretion

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

......................................................... 40 Coproporphyrinelevation

................... ... 40 Cognitive (CNS) deficits

.................... 50-00 Peripheralneuropathics

......................... 50-00 Encephalopathic symptoms

.................... 80-100 (P.13-8) The first physiological effect associ. ated with increasing blood lead levels istheInhibition 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 for8-ALAD inhibition in children is 10 jigPb/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 begunto 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 ofheme synthesis untila 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 .ofimpaired heme synthesis, and

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

## 46252

HeinOnline -- 43 Fed. Reg. 46252 1978the possibility that 8-ALA accumulationisitselftoxic 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 usedby 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 ofthe information provided by the air quality criteria document as wellas the evidence and arguments offered bymedical 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 riskto health atthe point where the elevation ofEP can firstbe 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 childrenwithbloodlead levels of50pg Pb/dl.

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

(1) The maximum safe blood lead level should be somewhat lower than the threshold for a decline in hemoglobin levels (40pgPb/dl).

(2) The maximum safe blood lead level should be at an even greater distance below the threshold forrisks 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 exposureby the Center forDis-

ease Control of the Public Health Service, as endorsed by the American -Academyof Pediatrics, because of elevation of erythrocyte protoporphyrin (above 30pgPb/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 ofEP (15-20 pgPb/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) of1.3 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 ofthepopulation below thelevel ofan 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 usedaGSD 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 of5 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.
CoNTaIuTIONToTOTAL Lnw ExPosuRE FROM NONAM SouRcEs

In the proposed standard, EPA .argued that the air standard should take into account the contribution to bloodlead 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 safelevelEPA 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 ofvarious sourcesto 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 bloodlead 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 hasbeen done with evaluation of evidence from general epidemiological studies, studies showing deCline ofbloodlead levels withdecrease in airlead, studies ofblood leadlevels in areas with low air lead levels, and isotopic tracingstudies.

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 forchildren was from 16.5 pgPbldl to 46.4 pg Pb/dl with most studies showingmeanlevels greater than25 pgPb/ dl (Fine, 1972; Landrgan, 1975; von Lindern. 1975). EPAbelieves thaf, for many of thesepopulations, thecontribution tobloodlead levels fromnonair

sources may exceed the desired target
mean bloodleadlevel.

In a number ofstudies, reduction in air lead levels resulted in a decline in children's blood leadlevels.A study of blood lead levels in children in New York City showed, that children's

mean blood lead levels declined from 30.5 pgPb/dlfrom 1970 to 1976, while during the same period air lead levels at asingle monitoringsitefell 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 thedrop inblood leadlevels. ,

EPA has also examined epidemiologIcal studies in the criteria document where air lead exposure is low, and

canbe assumed tobe 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 BLOODLEADLEVELSIN CHILDREN EXPOSEDTO MODERATE TOLOW Am LEAD LEVELS

Investigator Blood Airlead2 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 to0.7

.......... ChildreninBenecla Calif. 0.3 to'0.6

Childrenin. JCrocket,Calif.. Johnson, TiIery, 1975............10.

.... Female children-mean age 9 in Lancaster Calif.

'In micrograms oflead per deciliter. 2Inmicrograms oflead perctbic meter.
Therange ofmean bloodlead levelsJin those studies is from 10.2 jig Pb/dI to 14.4'lpg Pb/,dl, with an average at12.7 pgPb/dl.

In addition to epidemiological investigations, EPA-has reviewed studies that examine the-source ofblood lead by detecting characteristic lead isotopes. A study using isotopic tracing (Manton, 19.77) suggests thatforseveral adults in Houston, Tex., 7 to 41 per-. cent ofblood lead could be attributed to air lead sources. An earlier isotopic -study .(Rabinowitz, 1974) concluded that for two -aduflt'malesubjects studied, approximately one-third of total daily intake of lead could be attributed to exposure to airleadlevels of1-2 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, soiland dust.

From reviewing these areas of :evidence,EPAconcludes that:

1. In studies showing -nean blood lead levels above 15 pg Pb/d, it is probable that both air and nonair

sources oflead contribute significantly to bloodlead with the possibility that contributions from ,nonair sources exceed 15 pgPb/dl.

2. Studies showing -asustained 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 14.4pgPb/di.'

3. Isotopic tracing studies showt air contribution to blood lead to -be7-41 .percent in one study and about 33percentIn another study.

In considering -this evidence, EPA
notes that if, from theisotopic Studies, .aproxmatlytwo~thirds ,of blood

iead s typically derived from honair
sources, a-meanblood lead'target of 15 pg -Pb/diwould 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 lowis 12.7 )igPb/di. 

### Inthe absence of' more precise information, EPA is calculating th6 lead standard based on the attribution of 12 pg Pb/ dl ofthe-blood leadlevel 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 alarger estimate of non-air contribution to bloodlead, the -resultwould be an exceptionally-stringent standard, which would-not address the principal source ofleadexposure.
THE'RELATIONSHIP BE wN AIR m-AD

ExPosURE AND RESULTING

- BLOOD IXADIZVL
E:A hai reviewed the studies discussed in the criteria -documentwhich 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 usedperson- -aLdosimeters to measure lead intake. This eliminated some oftheulicertainty,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 ofadults, *Griffinet al., gives roughly the same conclusion for a group of adults confined to a chamber with ontrolled exposure to lead aerosol. This studywas conducted

over a'three month period with .control over lead ingestion. As air lead. levels in the chamber were increased from 0.15 -pgPb/m3 .to 3.2 pg Pb/m3

, the air lead-to blood lead relationship

was -1:1.7.

Because children are knownto have greater net absorption and retention oflead than adults, it isreasonable to

assume that the-airlead to -bloodlead relationship for thissensitive population, exposed to air leadlevels in the range of the _proposed standard, is equal to ifnotgreater 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 ofblood 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 thelow range is larger thin in theAzar 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 -feltthat 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:
ratiosbetween bloodlead levels and airlead exposures were shown to range generally from 1:1 to 2:1. These were not, however, constant over the range of airlead concen- trations encountered. There ar6 suggestive data Indicating that the ratiosfor children

.areIn 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 TuEAIR STANDARD

EPA has calculated the standard based on the conclusions reached In the previous sections;

1.Sensitive population: Children. ages1-5. 2.Health basis: Maximum safe blood lead level for individual children Is 30 pg Pb/di -basedon concernforimpaired heme synthe- sis above .30pg Pb/dl and margin o1 safety for anemia above 40jg Pb/d and ngrvous system deficitsabove 50pg Pb/dI.

3. Maximum safe geometric mean blood lead for children based on placing 99,5 percent of the sensitive population below the 30pg Pb/al level ofconcern: 15pgPb/d.

4. Estimate ofblood lead level attributed to non-airsources: 12pgPb/dl.

5. Allowable contribution to blood lead frotm air sources after achieving the stand. ard: 15pgPb/dl-12pg Pb/dl=3pg 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

### pgPb/m.

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

HeinOnline -- 43 Fed. Reg. 46254 1978SELECTION OFTHEAVERAGING PERIOD FOR THESTANDARD
Based on. comments received and consideration by the Agency, the proposed-averaging period of a calendar month is extended to a calendar quarter. EPAbelieves 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 ofState and local environmental agencies, or significantly reducing the protectiveness ofthe standard.

The Agency believes that the key criteria for the averaging period isthe protection of the health of the sensitive population. In proposing the 1.5 jg Pb/m3 standard, EPA concluded that -thisair level was safe for young children with an indefinie exposure period.The critical factorin 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 onthefollowing factors:

(1) From actual ambient measure- ments, there is evidence that the distribution of airlead levels is such that if the quarterly average was achieved -there is little possibility that there could be sustained periods greatly above theaverageyvalue.

(2) While it is difficult to relate the extent to which a monitoring network actually represents the exposure situationforyoung 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 suchlevels for the full 24-hour period reported by themonitor.

(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 ashort-term period ofexposure to elevated airlead.

(4)Direct exposure to air is only one of several rputes of total exposure. Thislessens the impact of a change in airlead onbloodleadlevels.

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 ofthe standard.

MARGIn OFSAFE

The Clean Air Act instructs EPA to set the level ofan ambient air quality standard at a level which protects the publichealth with a margin ofsafety. 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 orsuspected health effects, the size ofthe population atrisk, and possible interactions of several pollutants in potentiating health effects. While the margin ofsafety isbasek on available scientific information, this factor isjudgmental in that the AdminI trator mustweigh the acceptability ofes- timated risk.

Estimating an appropriate marginof safety for the air lead standard in complicated by the multiple sources and media for lead exposure. Because ofthis, EPA has elected to usemargin of safety considerations in estimating the maximum safelevel forbloodlead, 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 frompublic comment, bloodlead 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 50jig 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 bloodlead levels ofconcern.

Because of the variability between individuals in a population experiencing agivenlevel oflead exposure, EPA finds that it is notpossible 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 pigPb/di, 86 percent of the children would be below 20 pug Pb/dl, 97.5 percent would bebelow 25 pigPb/ 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 pgPb/di.

In determining the appropriate margin of safety, the Agency has also included consideration of the &followingfactors:

(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 notbeenfullystudied.

(2) There are nobeneficial effects of lead atcurrentenvironmental 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 aswater, soil and dirt,and food.

(4) Lead is chemically persistent and with continued uncontrolled emissions will continue to accumulate both in human tissueand in the environment:

(5) There is a possibility that lead expospre resulting in blood lead levels previously considered safemay 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 atbloodlead levels below30 Pb/ dlforindividual children.

TMPACT OF LEAD DUSTrALL ON BLOOD LEAD

In thepreamble for theproposed air standard for lead, EPA pointed out that the significance of dust and soil lead as indirectroutes 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 ofthe lead available in contaminated dust and soil. EPA is also con- cerned that the deposition ofleadparticles can lead to general contamination ofthe 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 -reviewedin the criteria document indicate a correlation between soil and dust levels and childrens' blood lead levels inhighly contdiminatedenvironments (Yankel and VonLindern, 1977; Barltrop, 1974; Galke, in press). The lead threshold for concern has been reported as'1,000 parts per million (ppm) in soil (Yankel andvon Lindern, 1977). At levels of between 500 and 1;000 ppm insoil; 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 percentrise inbloodleadlevels. Below 500 ppm lead -in soil, no correlation has been observed with blood lead levels. *-

The normal background for lead in soilis 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 byEPA's Offise of Pesticides Programs from 1974 to 1976 in 17 urban areas reported onlyk3 ,citieswith arithmetic mean concentrations in excess of 200 ppm, withthe highestvalud 537ppm. Concentrations in the soils surrounding large point

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

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,andremovalIechanisms.

EPA believes, however, that-significant impacts on bloodlead-of-soil nd dust lead are mainly limited to areas ofhigh soil concentration (inexcess of 1,000 ppm)around large pointsources and heavily- travelled roads. Evidence suggests that soil lead-levels in,areas with air lead levels inthe range ofthe standard are below the"threshold for ,leadhealth impact (Johnson, Tillery, 1975; Johanson, 1972; EPA, 1975 Air Quality Data andSoilLevels).

Comments ,received on the proposed standard argued that the lead -air standard should be limited-torespira- ble size lead particulate matter, as larger' particles would fall to the ground without being deposited or absorbed in the lung. "EPAhas decided not to accept thisrecommendation 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 orweathering. 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 primarystandard. EPA maintains its position that the primary air quality standard 'will adequately protect againstknown and anticipated adverse effects on public welfare. EPA 'does not have evidence that amore 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, ,nordo adverse effects in animals occur at lower levels of exposure than.com- parable effects inhumans.

Lead is absorbed but not accumulat-

- ed to any great extent by plants from

soil. Lead is, either unavailable to plants orisfixed in theroots 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 isno evidence to indicatethat ambient levels oflead result in significant damage to manmade materials. Effects of-lead on visibility and climate areminimal.

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 fornorwas it usedin 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 oflead emissions are primary lead and copper smelters, secondary lead smelters, gray iron foundries, gasoline lead 'additive manufacturers, and lead storage battery manufacturers. This analysisfurther indicates that someprimary 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, alonger 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 tolead.

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 forlead,

Based on Its toxicity, EPA has n. cluded lead on Its listofpriority 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 ofbest 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 andspecify disposal procedures for lead pesticides. Use oflead in pesticides is a small and decreasing proportion of total lead con- sumption in theUnited 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 1978EPA 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 othervehicles certified for

use ofunleaded fuel. Theformer regulations arebased onreducing 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 ofparticulate matter emissions generally use control techniques whichreduce lead emissions as
one component ofparticulatematter.

The Occupational SafetyandHealth 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 ofsafety. 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 standardfor lead.

The Department of Housing and

- Urban Development (HUD) has re- quirments for reducing human expo-
sure tolead through theprevention of lead poisoning from ingestion ofpaint 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 hazardfromlead-based paint; (3) notification ofpurchases ofHUD-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 regulationsin September 1977whichban: (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 conclusionthatIt is in the public Interest to reduce the risk of lead poisoning to young children from ingestion ofpaint and other similar surface-coating materials.

The Food and Drug Administration (FDA) adopted in 1974 a proposed tol-

erance forlead of0.3 ppm inevaporated milk and evaporated skim milk. This tolerance isbased onmaintaining children's blood leadlevelsbelow 40pg 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 intakehas notbeen established.

The Center for Disease Control (CDC) concluded in 1975 that undue

or increased lead absorption exists when a childhas confirmed bloodlead levels of30-70 pg Pb/dl or anEP elevation of 60-189 pg Pb/dl except where the elevated EP level Is caused byiron deficiency.

In developing the lead air standard, EPA has estimated both individual and population bloodleadlevelswhich it regards as safe targets. The Agency believes that these targets do notnec- essarily serve as precedents for other regulatory programs. There bre three

reasons forthisview:

(1) These targets were selected on thebasis ofwhat the CleanAirActre- quires. Otherprograms have otherlegislativerequirements whichwouldlead to adoption ofdifferent butequallylegitimate goals.

(2) The scientific data provided by the air quality criteria allow compari-

son of airlevels withblood leadlevels, butanalogous 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, andnonfood ingested Items. Be-

cause of this, FDA, CPSC and other EPA standards have been based on es- timates ofacceptable daily dose rather than onbloodlead targets.

(3) Studies currently underway may provide new information relevant to estimatingsafelevels oflead exposure.
Commlrs Br Orn s FEALAGscrrs

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 ofpublic health. CDCIs fully satisfied thatEP elevation does indeed represent a subclinical manifestation of lead toxicity and that young chil

### 46257

dren are thepopulation 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 madein arriving at the proposed air standard. CPSC concurred with the position thatchildren are thepopulation atenhanced risk toleadexposure, andthat the goal of a mean population blood leadlevel forchildren of15pgPb/dl is sufficiently low tobe protective of the population at enhanced risk of exposure. CPSC views the selection,ofEP 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 thatthe contrbuton..of nonair sources to lead body burdenmust be evaluated insettingthe air standardand suggeststhat
a larger nonair contribution, such as 13.5 pg Pb/dl used in the California standard. mightbeconsidered.

The Food and Drug Administration commended EPA'sproposal 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 15pgPb/dlis areasonable maximum blood lead level to use as an average national goal for children aged 1 to 5, although FDA suggests that foryoung children the margin of safety isdisturbinglynarrow.Thedivision of the 15pg Pb/dIinto 12pgPbh dl for nonair sources and 3pg Pb/dl for air sources was not unreasonable inFDA'sview.

The OccupationalSafety andHealth Administration endorsed EPA's pro- posed standard for lead and agrees withEPAthat 15 pgPb/dlasan average national blood lead level goal for young children is reasonable. OSHA views their proposed standard of 100 pgPb/m, 8-hour time-weighted average, and their establishment,of40 pg Pb/dl asthe thresholdeffect levelfor workers as consistent with the EPA proposed standard.

The Department of Transportation (DOT) endorsed the proposed standard of1.5pg Pb/m. Based onananalysis of the impact of the proposed standard on the highway program, DOT concluded that itis highly prob- able that transportation-related violations of the proposed standard would belimitedtolargeurbanareas.

In commenting on the proposed standard,.theDepartment oftheInterior (DOI) expressed concern thatthe burden for meeting the proposed standard will fall primarily on lead and copper smelters andbattery manufacturers, and commented on theFEDERAL REGISTER, VOL 43, NO. 194-THURSDAY, OCTOBER 5, 1978

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### 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 ofthe 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 oflead 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 ofthe 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 ofdifferences 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 aroadway, to minimize thiserror.

One commenter pointed outthat the proposed sampling procedure does not collect gaseous (organic) lead com- pounds and recommended that EPA consider requiring the use of amethod 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 notjustified 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 isbased on measuring thelead 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. (inpress.) 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, SupplementVol 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 theScience Advisory Board, Washington, D.C., October7,1977,

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, September25, 1972.

Johanson. W. C, and

. P. Luby.A Report
on a Study to Determine the Blood Lead Levels in Dallas Children.DallasHealth Dopartment, Dallas,Tex. 1972.

Johnson, D. E.,J.B. Tillery, and R J.Provost. Levels ofplatinum, palladiumand lead in populations ofSouthern California. Envi-

ron.Health Persp. 12:27-33, 1975.

Landrigan. P. J., S. H. Gehlbach, B.F.Ro senblum, J.M. Shoults,et al. EpidemicLead 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, LosAngeles, 1974, 120 pp.

U.S.* Environmental Protection Agency. Air Quality Criteria for Lead Office ofResearch and Development, Washington, D.C, 20460. EPA-450/8-77-017, December 1977.

vonLindern, I. andA.J.Yankel,Presentationto 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 SilverValley leadstudy. Therelationship 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 (42U.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.Principleandapplicability. 1.1 Ambient air suspended particulate matter is collected on a glass.fiber filter for 24hours using ahigh volume air sampler,

1.2 Leadinthe particulate matterissolubilized by extraction with nitric acid (HNO.), facilitated byheat or by a mixture

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

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### RULES AND REGULATIONS

ofENO and hydrochloric acid (HCl) facilitated byultrasonication.

1.3 The lead content of the sample is analyzed by atomic absorptionspectrometry using an air-acetylene flame. the 283.3 or 217.6 nmlead absorption line, and theopti-

muminstrumental-conditions recommended bythe manufacturer.

1.4 The ultrasonication extraction with HNOJ/HC1 will -extract metals other than leadfrom ambientparticulate matter.

2. Rlange, sensitivity, andlowerdetectablie Zimt.The values given below are typical of the methods capabilities. Absolute values will varyforindividual situations depending

on the type of instrument used, the lead line,and operating conditions.

2.1 Range. -The typical range of the method is0.07 to 7.5 jgPb/m3 assuming an upper linear range ofanalysis of 15 jig/ml and an airvolumeof2,400 i 3

.

2.2 Sensitivity.Typical sensitivities for a. 1 percent change in absorption (0.0044 absorbanceunits) are 0.2 and 0.5 jigPb/ml for the 217.0 and283.3 nmlines,respectively.

2.3 Lower detectable limit (LDL)-.A typical LDL is-0.07 jig Pb/m3!.The above value

was calculated by doubling thebetween-laboratory standard deviation obtained for the lowest measurable lead concentration in a collaborative test ofthe method.(15) An air volumeof2,400 m3was 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 reportingtheir 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, theInterference can be verified and correctedfor by carrying out the analysis with and without the method ofstandard 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 lowlead concentrations. (2) The interference is greater at the 217.0 'umlinethanatthe 283.3 nm line.No Interference was observed using the 283.3 nm linewith a similarmethod.(1)

Light scattering interferences can,however, be corrected for instrumentally. Since the dissolved solids can vary depending on the originofthesample, 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. Aless accurate correctioncan be obtained by using a nonabsorbing lead line that is near thelead analytical line. Information on use of these correction techniques can be obtained from instrument manufacturers' manuals. ,

If instrumental correction Is not feasible. theinterference canbe eliminated by use of the ammonium pyrrolidinecarbodithioatemethylisobutyl ketone, chelation-solvent ex- traction technique ofsamplepreparation.(8)

4.Rrecisionandbias. 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 to125 Ag/rm.(9) The combined ex- traction-analysis .procedure has an average within-laboratory relative standard deviationof 5 to6 percent over therange 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 ofeither extraction procedure.

4.2 Single laboratory experiments -and collaborative testing indicate that there Is

nosignificantdifference Inleadrecoverybetweenthehotandultrasonic 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

orelectrodeless dischargelamp.

5.2.1.1 Acetylene The graderecommended by the instrument manufacturer should be used. Change cylinder when pressure dropsbelow50-100 pslg.

5.2.1.2 Air. Filtered to remove partculate,oil, andwater.

5.2.2 Glassware. Class A borosilicate glassware should be used throughout the analysis.

5.2.2.1 Beakers. 30and 150 ml. graduated, Pyrex.

5.2.2.2 Volumetricflasks. 100-ni]. 5.2.2.3 Pipettes.To deliver50. 30,15.8. 4. 2.1ml.

5.2.2.4 Cleaning. All glassware should be scrupulously cleaned. The following procedure~s sugested.Wash withlaboratory detergent, rinse,soak for4hours In20percent (w/w)HNO,. rinse 3 times with distilled. delonized water, and dry in a dust free

manner.

5.2.3 Hotplate. 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 bathhave been foundsatisfactory.

5.2.5 Template. To aid In sectioning the glass-fiber filter. See figure 1 for dimensions,

5.2.6 Pilzz cutter.Thinwheel. Thickness <lmm.

5.2-7 Watchglass. 5.2.8 Polyethylene bottles.For storage of samples. Linear polyethylene gives better storage stability than other polyethylenes and ispreferred.

5.29 Paraflim "W".0 American Can Co., Marathon Products,Nennah. Wis., orequiv- 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 specificationshave beenmetby EPAcontractors.

6.1.L1 Lead content. The absolute lead content of filters is not critical, but low values are, ofcourse, desirable.EPA typically obtains filters with a lead content of <75 j9g/fllter.

It is Important that the variation Inlead content from filter to fter, within a given batch, besmall

6.1.1.2 Testing.

. 6.1.1.2.1 For large batches of filters (>500 filters) select atrandom 20 to 30 flters from a given batch. For small batches (<500 filters) a lesser number offilters may be taken. Cut one 2/x8' strip from each

*Mention of commercial products does notImply endorsement by theUS. EnvironmentalProtection Agency. filter anywhere in the filter. Analyze all strips, separately, according to the directions insections 7and8-

6.1.1.2.2 Calculate the total lead in each filter as

F Pbml x100 MI X12 

### strips Fb= pg Pb/mI x 100T~ r 2

l fite bstrp

- f!ilterwhere:
Pb-Amount ofleadper 72 square inches of filter,jig.
6.1.1.2.3 Calculate the mean. F.,of the values and the relative standard deviation (standarddeviation/mean x 100. if therelative standard deviation is high enoughso that, In the analysts opinion, subtraction of F. (section 10.3) mayresult in a significant

error Inthe pgPb/m3-the batch shouldbe rejected.

6.1.124 For acceptable batches, use the value ofPb to correct all lead analyses (section 10.3) of particulate matter collected using thatbatch of flters. If the analyses

are below the DL (section 2.3) no correc- tionisnecessary.

6.2 Anaysls.
6=1 Concentrated (15.6 A0 HNO ACS reagent grade HNO and commercially avalableredistilledHNO. hasfoundtohavesuffclientlylowleadconcentrations.

6.2.2 Concentrated (IL7 M) HCL ACS reagent grade.

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

6.4 3At HNO. This solutlon is used in the hot extraction procedure. To prepare, add 192 ml of concentrated HNO. to D. water ina I !volumetric fssk.Shake well cool and dilute to volume with DI. water./ Caution:Nitric acid fumes are toxic. -Pre pare n a wellventilatedfume hood.

6.25 0.45 MHNO. 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 waterIn a 11volumetric flask. Shake well, cool, and diluteto volume with D.Lwater.

6a6 2.6 A HNOb+0 to 0.9 A HCL This solution Isused in the ultrasonicextraction procedure. The concentration ofHCIcanbe varied from0 to 0.9

.. Directions are given for preparation of a 2.6 AfrHO0.9 MHCI solution. Place 167 mlofconcentrated ENO. into a 11 volumetricflask 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, anddilute to1 L

6±9-7 OAOMHNO +XMrHCLThissolution Is used as the matrix for calibration standards when usingtheultrasonic extraction procedure. To prepare, add 26 ml of concentrated HNO,, plusthe mlof HC1 re- quired, to a 1 1volumetric flask. Dilute to nearly 1 1with D.I water cooltoroom 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 - mlofconcentrated HCI required.

x - molarity ofHCI in6.2.6. 0.15 = dilutionfactor in 7.2.2.

6.2.8 Lead nitrate,Pb(NO.).. ACSreagent grade, purity 99.0 percent. Heat'for 4 hours
at 120" C andcool ina desiccator.

6.3 Calibration standards.. 6.3.1 Master standard, 1000 pg Pb/ml in HNO,. Dissolve 1.598 g ofPb(NO.). in.0.45 M HNO, contained in a 1 1volumetric flask and dilute to volume with 0.45MHNO

.

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 alsobe used.

7.Procedure. 7.1 Sampling. Collect samples for 24 hours using the procedure described in reference 10with 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 cuttingprocedures may beused.

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 ofthe 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 beanalyzed.

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 beakerwith awatch glass.

7.2.1.3 Place beaker on the hot-plate, contained in a fume hood, and boll gently for 30 min. Do not letthe sample evaporate to dryness. Caution:Nitric acid fumes are toxic.

7.2.1.4 Remove beaker from hot plate andcool to nearroom temperature.

7.2.1.5 Quantitatively 'transfer the sample as follows:

7.2.1.5.1 Rinse watch glass and sides of beaker 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 markon beaker, cover with watch glass, and set aside for aminimum of30 minutes, This Is acritical step _and cannot be omitted since it allows the HNO, trapped in thefilter to diffuse into the'rinse water.

7.2.1.5.4 Decant the water fromthe filter intothe volumetric flask.

7.2.1.5.5 Rinse filter and beaker twice with D.f. water and add rinsings tovolumetricflaskuntil totalvolumeois 80to 85 ml.

7.2.1.5.6 Stopper flask and shake vigorously. Setaside 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. hourbeforeproceeding with analysis. 17.2.1.5.9 Ifsample 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" x8" strip from the ex- posed filter asdescribed insection 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 withparafilm.

Th'e parafilm should be placed over the beaker such that none ofthe 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 foraminimum of30 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 nowin 0.45 MHNO,. Samples prepared by the ultrasonication procedure are in0.40 MHNO + X MHCI.

8.Analysis.

- 8.1 Set the wavelength ofthe monochromator at 283.3 or 217.0 nm. Set or align other instrumental operating conditions as recommended bythe 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 eithercase, care should be taken not to disturb thesettled solids.

8.3 Aspirate samples, calibration standards and blanks (section 9.2) into the flame and- recordthe 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 iftheultrasonic extraction procedure was used) to 100 ml with acid of the same concentration as used inpreparing 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 beused.

Volume of20 Finalvolume. Concentration pg/mlworking ml pgPb/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 forpreparation of a calibration

curve can be given. Select standards .(plus thereagent 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 ofthe 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 thelinear 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 than5 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 airvolume as

Qi + Qf
Vm = 2 xT

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

. O

1=Initia airflow rate, m3/min. Qt=Final airflow 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 Bofrefer-

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 arestandard cubic meters, sm3 .

VSTP = V P2 xT 1

Vnp=Sample volume, sm3

, at 760 um Hg and 298' K, V,=Measured volumdfrom 10.1. P,=Atmosbherlc pressure at time of orifice calibration,nunHg. P,=760 mnm Hg.
T =Atmospheric temperature at time of orifice calibration, *K. T,=298"K.

- 10.3 'Lead concentration. Calculate lead concentration inthe air sample.

(ug Pb/mlx 100 ml/stri x 12 strps/fliter)

- r b C-

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

HeinOnline -- 43 Fed. Reg. 46260 1978where: C=Concentration, jgPb/sm'. jg Pb/ml=Lead concentration determined fromsection 8. 100 m/strip=Total samplevolume. 12 strips/filter=Useable filterarea, 7" X 9"/ Exposedarea of one strip,T" X 7". Fb=Lead concentration of blank filter, A±g, fromsection 6.1.1.2.3. Vs-=Air volume from 10.2.

11. Qualitycontrol %"x 8"glass fiber filter stripscontaining 80 to 2000 pg Pb/strlp (as lead salts) and blank stripswith zero Pb content should be used to determine if the method-as being used-has any bias. Quality control charts shouldbe established tomonitor differences between measured and truevalues. The frequency of such checks will depend on the localquality control program.

To minimize the possibility of generating unreliable data,the usershould follow practices established for assuring the quality of air pollution data, (13) and take part in .EPA's semiannual audit program for leadanalyses.

12. Troubleshooting. 1.Duiring extraction ofleadby thehotex- 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 ofthe nebulizer. Howev'- er, different nebulizers may requirejower acid concentrations. Lower concentrations

canbe used provided samples and standards have the same acidconcentration.

3. Ashing 6f particulate samples has been found, by EPA and contractor laboratories, tobe unnecessary inlead analyses by atomic 

### RULES AND REGULATIONS

absorption. Therefore, this stepwas omitted fromthemethod.

4. Filtration of extracted samples, to

remove particulate matter, was specifically excluded from sample preparation, because

some.analysts have observed losses of lead dueto filtration.

5. If suspended solids should clog the ne- bulizer during analysis of samples, centrifuge the sampleto 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 ofNASN Atmospheric Particulate Samples for Lead." Envir.ScL andTcch., 10,877-880 (1976).,

2. Skogerboe R. K. et al. "Monitoring for Lead in the Environment" pp. 57-66. Department of Chemistry, Colorado StateUniversity, Fort Collins, Colo. 80523. Submitted
to National Science Foundation forpublications, 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 andTech., 3, 472- 475 (1969),

7. "Proposed Recommended Practices for Atomic Absorption Spectrometry." AS.TM 

### 46261

Book ofStandard% part 30. pp. 1596-1608 (July 1973).

8. Koirttyohann, S. R. and Wen. J. W. "Critical Study ofthe APCD-MIBKExtraction System for Atomic Absorption." AzaL Chem., 45, 1986-1989 (1973).

9. Collaborative Study of Reference MethodfortMe Determinationof Suspended Particulates in the Atmosphere (High Volume Method). Obtainable from National Technical Information Service, Department ofCommerce, PortRoyal Road, Springfield, Va.22151, as PB-205-891.

10. "Reference Methodfor theDeterminationof 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 ofUrban Air." JAPCA,16, 77-78 (1966).

12. EPA Report No. 600/4-77-034. June 1977. "Los Angeles Catalyst Study Symposlum." Page223.

13. QualityAssurance Handbook forAir PollutionMeasurementSystem. Volume IPrinciple& EPA-600/9-76-005, March 1976. 14.Thompson, R. J.etal, "Analysis ofSelected Elements In Atmospheric Particulate Matter by Atomic Absorption." AtomicAbsorption 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." Industrialand EngineeringChemistry,49,1131-1142 (1957).

-

17. QualityAssurance Handbook for Air Pollution Measurement Systems. Volume lI-AmbfentAirSpecificMethods.EPA-600/ 4-77/027a May1977.

[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