Review of the Scientific Basis for EPA's
(Environmental Protection Agency's)
School Asbestos Hazard Program, with
Recommendations to State Health Officials
(U.S.) National Inst, for Occupational
Safety and Health, Cincinnati, OH
Oct 84
a
U.S. Depjrtnwnt of Cmiiere®
Natimai Tedwol kMi Urnu

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P!i85-22 1 4U8
1 REPORT DOCUMENTATION
PAGE
1. REPORT NO.

J. RoctpMnr* Aocoosion No.
| 4. THto oftd Qufrtftlo
A Rcvieu Of The Scientific Basis For EPA's School Asbestos
S. Report Ooto
84/10/00


7. Autrywit)
Anonymous
& Porform'rta Orsoniiotion Ropt. No.
9. PorfomnoQ Ofsonifotton Homo end Atfdrofto
NIOSH, U.S. Department of Health and Human Services,
Clncinnat i, Ohio
10. Proi©ct/To*Ji/Worti Untt No.
11. ControcttO or GrontfGl No.
fC)
< G)
12. Spo*v»«r4n(j OrtjnnLidtIon Name ood Addroao
A3 BOX 9
IX. Typo of ftoport & Period Covorvd
W.
Haiard Proposa 1 Ui\_h Recommendations To State Health Officials,0-
IS. SuDoVcmorrtary Noaou
iO. Abstract (Umlt 200 wortfci)
The basis for the school asbestos (1332214) haiard program of the
Environmental Protection Agency (EPA) is reviewed. Risk of disease following
asbestos exposure is discussed For industrial exposures, lung cancer rists
cluster between 1 and 10 p e r r: ,-i t per fiber year per milliliter For
mesothelioma, estimates range "rom 0.01 to 0.06 percent. For nonoccupational
exposure, lung cancer risks range from 2 to 40 per million exposed persons
Mesothelioma risks range from 2 to 100 per million The indirect quantitative
risk assessment of EPA for asbestos associated cancers due to exposures at
schools in early life is discussed As of May, 1982, approximately 8,600
schools contain friable asbestos and approximately 2 to 6 million students and
100,000 to 300,000 teachers, administrators, and other staff are potentially
exposed to airborne asbestos in these schools . EPA estimates that over the next
30 years, approximately 1 , 0 0 0 premature deaths' will result from current and
future exposures to asbestos released from friable building materials
Attention to environmental sources of asbestos by EPA have focused on potential
risks for children because they are more active than adults, breathe at higher
rates, and breathe more often by mouth
17. Ooeu/nefrt AnofjnUo o. Descriptors
b.	Ton-no
NIOSH-Publ ; cat ion, NIC >H-A'jt hor , Resp l r ab 1 e-dust
I ndust r i a I-dust s , R i sk-ana1ysls , E n v l r o nine r, t a 1 - e x po su r e ,
Quantitative-ana1ysis, Health-protection, Health-standards,
Protectlve-measures
c.	C03AT1 FkAJ/Q/cuo
Alrborne-flbe r s
1-8. Qutz*iwnt
1C. 09CU*fy CLrefl <7h*o ftiOOrt)
21. No, o* hqw
m. ClftM
n.

jAotrvtffto* o*
NOTICE: This material may be protected
by coj;yri£ht law (Title 17 U.S. Code)
oTisnM rosad m 
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A REVIEW OF THE SCIENTIFIC BASIS FOR EPA'S SCHOOL ASBESTOS HAZARD PROGRAM,
WITH RECOMMENDATIONS TO STATE HEALTH OFFIC_ALS
CENTERS FOR DISEASE CONTROL
October 1984
INTRODUCTION
In view of the carcinogenic potential of inhaled asbestos fibers, public
health officials should identify the presence (or confirm the absence) and
evaluate^the potential hazards of environmental exposures to asbestos released
from controllable bulk sources in consumer products. Evaluations of school
buildings have revealed the widespread presence of potentially hazardous
asbestos-containing materials, with some surfaces found to be heavily damaged
or deteriorated.
The Environmental Protection Agency (EPA) has placed the legal burden of
administering the mandatory school asbestos hazard program on local and State
educational agencies; however, the lay public members of these agencies may
lac^ sufficient guidance as to 1) the training, technical consultation, and
standardized methods necessary to conduct valid and reliable environmental
sampling and analysis of bulk asbestos, 2) the limitations (sensitivity,
specificity, limits of detection, and quantification) of available bulk- and
air-sampling methods, 3) the quantitative risk assessment of the airborne
hazard potential of any bulk asbestos identified by the sampling and
analytical program, 4) what to tell the nonoccupationaily exposed groups
(students, parents, and community members) about their level of risk, for
asbestos-associated diseases, 5) what to tell the occupationally exposed
groups (the administrative, teaching, custodial, and maintenance staffs) about
their risks, especially if the implementation of control measures requires
contact with hazardous bulk asbestos, 6) how to decide whether to implement a
control program, and 7) how to choose between alternative control measures.
Reliable and precise, standardized methods of sampling and analyzing bulk
asbestos should precede the application of equally valid, standardized
evaluation criteria in the process of recognizing, evaluating (predicting),
and controlling environmental hazards caused by airborne asbestos.
Quantification of airborne asbestos fiber concentrations by air sampling is
not an appropriate first approach because 1) it requires a relatively high
level of expertise and expense, especially in view of the large number of
buildings involved, and 2) it indicates only current airborne fiber
concentrations, and thus the risks for transient and peak exposures due to
episodic releases of fibers from bulk material are not reflected.
A consistent national approach is essential If the desired public health
benefits of this program are to be realized and the impact of the program is
to be evaluated. The following review should be helpful to State health
officials who may be called upon to assist in designing, implementing,
interpreting, and evaluating nonindustrial asbestos hazard programs.
Enclosed for your information is EPA's document titled "Guidance for
Controlling Friable Asbestos-Containing Materials In Buildings."
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Under the authority of the Toxic Substances Control Act (1976), EPA
promulgated a mandatory program (40 CFR, Part 763) requiring all local public
school boards to assess the potential for hazardous inhalation exposures to
asbestos in primary and secondary schools by June 28, 1983 (_!.)• From March
1979-May 1982, the school asbestos program was voluntary, and EPA, in
collaboration with the U.S. Department of Health and Human Services (nee U.S.
Department of Health,, Education, and Welfare), the Occupational Safety and
Health Administration, the Consumer Product Safety Commiosion, and independent
consultants, prepared and distributed several guidance documents (2-9)» In
1980, EPA proposed the use of an Asbestos Exposure Assessment Algorithm, based
on the presence and description of eight factors for nonoccupational indoor
environments (10). In practice, each factor was to be rated and given a
numerical score; the sum of the scores then would provide a numerical index
that could be compared with a given corrective-action scale. In October 1982,
the EPA Region VII Asbestos Coordinator published an inspection manual for use
with the EPA algorithm (11). However, results with the algorithm have varied
greatly among both trained and untrained observers, and experts' scores have
shown poor comparability (12). To provide & less ambiguous basis for decision
making, EPA recently published a new guidance document that prescribes a
modified method for selecting a course of action based on the use of "yes" and
"no" responses rather than on the rating and scoring of each factor (13).
This review is to assist public health officials in providing up-to-date
advice and consultation to educational agency officials, often the lay public,
who have the legal responsibility to implement, interpret, and act upon these
asbestos hazard evaluations. This will update the Centers for Disease
Control's (CDC's) public health recommendations regarding asbestos hazards in
buildings, dated May 9, 1977 (14).
BACKGROUND ¦
Exposures to asbestos vary in nature, frequency, and duration, and they
decrease in approximately the following order of intensity: direct
occupational exposure (e.g., mining, milling, fabricating, or using
asbestos-containing materials); indirect occupational exposure (e.g., that of
an electrician working near an asbestos insulation worker); family contact
exposure ("take-home" from the workplace); and general environmental exposures
(e.g., from communitywide contamination near waste disposal sites, from
industrial point-source emissions and motor vehicle brake linings, and from
consumer products and damaged or deteriorated building materials made or
contaminated with asbestos) (15-7.8).
Risk of Disease After Industrial Exposures - Reliable population-based studies
on the increased, risk of asbestos-associated diseases (pulmonary fibrosis,
pleural thickening and asbestosis, lung cancer, and pleural or peritoneal
mesothelioma) have been reported for certain groups with nontrivial,
well-documented occupational exposures (29-34). The risk for both types of
asbestos-associated malignancies, lung cancer and pleural or peritoneal
mesothelioma, varies in a fashion consistent with a linear (nonthreshold)
dose-response relationship (29-34). However, we do not completely understand
the pathogenic mechanisms of mineral fiber-induced carcinogenesis, the
interactive effects of other risk factors, and the dose-response relationships
at extremely low levels of frequent or transient exposures (35-39).
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For lung cancer, excess risks per unit of exposure vary widely, but estimates
cluster between 1% and 102 for increased cancer risk per fiber-year/ml (30).*
In addition, the risk for lung cancer multiplies for cigarette smokers
occupationally exposed to asbestos at either high or low levels (16,30,34).
Age-standardized lung cancer death rates (deaths per 100,000 person-years)
among a large cohort of Insulators ranged from 11.3 for unexposed nonsmokers
to 58.4 for exposed nonsmokers and from 122.6 for unexposed smokers to 601.6
for exposed smokers (16). Since most lung cancers in both exposed smokers and
nonsmokers occur after age 60, the risk caused by asbestos exposure before age
50 (whether transient or continuous) is virtually independent of age at first
exposure and is simply proportional to the cumulative dose (34).
For mesothelioma, most estimates range from 0.01% to 0.06% (cumulative risk
after 35 years' latency) per fiber-year/ml; however, the risks may be five or
more times higher than this when exposures begin early in life (30-34).
Cigarette smoking does not appear to increase the risk for mesothelioma in
exposed individuals (34).
Risk of Disease After Nonlndustrial Exposures - Environmental contamination
with natural and synthetic mineral fibers is now so common (40,41) that
virtually all urban dwellers have some of these fibers in their lungs,
especially if they have had occupational or avocational exposures to
mineral-fiber dusts (£2,^3). Radiologically detectable plaques, or pleural
thickening and/or pulmonary fibrosis, have been associated with
nonoccupational (household contact) exposures (16). Although such
roentgenographic abnormalities can give evidence of asbestos exposure, they
are not diagnostic unless alternative traumatic,-infectious, medical,
surgical, and environmental etiologies are ruled out (44). Asbestosis, a
potentially disabling, nonmalignant, fibrotic lung disease, is highly
A In measurements of low-level environmental asbestos contamination, the total
mass concentration of asbestos fibers per cubic meter of air (ng/m^) is
estimated by electron microscopic (EM) techniques for counting and sizing
fibers (34,40). However, the most extensive and reliable exposure data
available for quantitative risk assessment are from studies of
occupationally exposed groups, measured by phase contrast microscopic (PCM)
and polarizing light microscopic (PLM) techniques and expressed in fiber
concentration (f/m^) for fibers detectable by light microscopic methods
(i.e., only those fibers longer than 5 ;um). Partly because of differences
in the specificity and sensitivity of these methods for identifying and
quantifying asbestos fibers, the conversion factor relating mass
concentration to fiber concentration ranges from 5,000 to 150,000 ng/m^
per 1,000,000 f/m^, with a geometric mean of about 30,000 ng/m^ per
1,000,000 f/m^ (i.e., about 30 f/ng) and a geometric standard deviation of
about 4,000 ng/m^ per 1,000,000 f/nr (about 250 f/ng). The geometric
mean of the range of conversion factors should be used for environmental
risk, assessment, with the low mass concentrations extrapolated from fiber
count (34) and with the large magnitude of variability noted in this
extrapolation (30,40). In this report, we will use the geometric mean
conversion factor of 30 fibers (longer than 5 ^un) per nanogram (30 f/ng) of
asbe3tos, keeping in mind thac the uncertainty about thi.3 conversion factor
is considerable (34,41).
3
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dose-dependent and clearly associated with industrial exposure (15,35-39);
there is no convincing evidence that disabling asbestosis is caused by
nonoccupational exposures to asbestos (34).
No reliable, population-based data are available on which to base a direct
quantitative assessment of the risk of asbestos-associated cancer due to
take-home or other nonindustrial exposures to asbestos (29-34). However,
numerous quantitative risk assessments have been based on indirect nechods,
explicit but different assumptions, and various sources of data on
environmental exposure concentrations (30,31,34). For individuals with
nonoccupational exposures to asbestos, Schneiderman et al. estimated an excess
lung cancer risk of 3-30 per million exposed persons (30), and Enterline
estimated the excess risk to be 2-40 per million (31). For individuals with
nonoccupational exposures to asbestos, the estimated excess mesothelioma'risks
were 4-24 per million (30) and 100 per million (31). A comprehensive review
of the risk assessments for exposures to asbestos and asbestiform fibers is
available in a report of the National Academy of Sciences (45).
Nelson et al. have provided the most recent and authoritative estimated risks
of death from lung cancer (Table 1) and mesothelioma (Table 2) according to
age at onset of nonoccupational exposure to asbestos, duration of such
exposure, sex, and smoking status (34).
A person's age at first exposure to asbestos is an important determinant of
risk of mesothelioma (34_). For both pleural and peritoneal mesothelioma,
incidence appears to rise as a function of the third or fourth power of time
since first exposure. This rise occurs irrespective of cigarette smoking;
however, the magnitude of the risk is related to both the concentration and
the duration of exposure. When exposure begins before age 20, the risk of
mesothelioma may be similar to that of lung cancer in smokers and may be
greater than that of lung cancer in nonsmokers, perhaps because of differences
in the pathogenic roles of asbestos in the multistage processes that produce
these different cancers (34).
Although we cannot prove that there is a linear, nonthreshold dose-response
relationship after nonindustrial exposures, it Is thought that euch a
relationship does exist, that exposure to respirable-size asbestos fibers
pose3 a carcinogenic risk for humans, that exposure beginning early in life
increases the risk for mesothelioma, and that no safe level of exposure to a
carcinogenic agent has been demonstrated; therefore, sources of asbestos that
are likely to result in hazardous exposures should be identified and
controlled (29-34).
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Table 1*
Lung Cancer: Estimated Risks of Death Per 100,000 Person-Years
Due Co Continuous Nonoccupational Asbestos Exposure,
by Age at Onset of Exposure, Duration of Exposure, and Smoking Status
Age at Onset Years of Continuous Nonoccupational Exposure (10,000 f/rn^)
of Exposure
(in Years) _1_	_5	_1_0	2jJ
Hale nonsmokers
<1
0.1 - 0,8
0.5 -
4.6
0.9 -
8.8
1.8 -
17.6
10
0.1 - 0.8
0.5 -
4.6
0.9 -
8.8
1.8 -
17.6
20
0.1 - 0.8
0.5 -
4.6
0.9 -
8.8
1.8 -
17.6
30
0.1 - 0.9
0.5 -
4.6
0.9 -
8.3
1.8 -
17.2
50
0.1 - 0.8
0.4 -
3.8
0.7 -
6.7
1.2 -
11.3
Male smokers
<1
0.8 - 8.4
4.2 - 41.6
8.4 - 83.6
16.7 - 166.7
10
0.8 - 8.4
4.2 - 42.0
8.4 - 84.0
16.8 - 167.6
20
0.8 - 8.4
4.2 - 42.4
8.4 - 84.4
lb.7 - 166.7
30
0.8 - 8.4
4.2 - 42.4
8.4 - 84.0
15.8 - 158.3
50
0.7 - 7.1
3.2 - 32.3
5.7 - 56.7
8.1 - 80.6
A This table was adapted from the Final Report of the Chronic Hazard Advisory
Panel on Asbestos to the Consumer Product Safety Commission (34).
Calculations were based on U.S. mortality rates for 1977, adjusted to
account for secular changes in the risk of lung cancer in male smokers
compared with male nonsmokers (34,46,47). Patterns for female smokers and
nonsmokers are similar to those given for males (34). From the authors'
linear, nonthreshold dose-response model, the risks for lung cancer can be
extrapolated from alternative assumptions of age at onset of exposure,
duration of continuous exposure, smoking status, and level of exposure (34).
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Tabls 2*
Mesothelioma: Estimated Risks of Death Per 100,000 Person-Years
Due to Continuous Nonoccupational Asbestos Exposure,
by Age at Onset of Exposure, Duration of Exposure, and Smoking Status
Age at Onset Years of Continuous Nonoccupational Exposure (10,000 f/m^)
of Exposure
(in Years)	]_	5	10	20
Hale nonsmokers
<1
3.7 - 37.4
17.1 - 170.9
30.7 - 307.0
49.4 - 493.5
10
2.4 - 23.5
10.6 - 105.8
18.8 - 187.7
29.2 - 291.9
20
1.3 - 13.4
6.1 - 61.3
10.5 - 1C5.4
15.7 - 157.1
30
0.7 - 7.1
3.2 - 31.5
5.3 - 52.5
7.4 - 73.9
50
0.1 - 1.3
0.5 - 4.6
0.7 - 6.7
0.8 - 8.0
Male smokers
<1
3.2 - 31.9
14.5 - 144.9
25.7 - 256,6
41.2 - 412.4
10
2.0 - 19.7
8.8 - 88.2
15.5 - 154.6
23.4 - 233.5
20
1.1 - 10.9
4.9 - 49.1
8.4 - 84.0
12.3 - 123.5
30
0.5 - 5.9
2.4 - 24.3
4.0 - 40.3
5.5 - 5'.4
50
CO
o
1
9
o
0.3 - 3.4
0.5 - 4.6
0.5 - 5.5
* This table was adapted from the Final Report of the Chronic Hazard Advisory
Panel on Asbestos to the Consumer Product Safety Commission (34).
Calculations were based on U.S. mortality rates for 1977 (34). Patterns for
female smokers and nonsmokers are similar to those given for males (34).
The risks for mesothelioma can be extrapolated from alternative assumptions
of age at onset of exposure, duration of continuous exposure, smoking
status, and level of exposure (34).
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£PA's INDIAICT gUAi\"T::.-.r:vf£ RISK ASSESSMENT /OR ASBESTOS-ASSOCIATED CA-S'CERS
DUi TO EXPOSURES AT SCHOOL IN EARLY LIFE
Because Che onset of dsbestos-associaced cancers generally follows initial
exposures only after long latency periods of 20 to 30 years or more, the early
recognition, evaluation, and control of potentially hazardous exposures to
asbestos are essential. This is especially true for environments in which
infanta, children, and young adults nay be exposed to airborne asbestos fibers
from a vide variety of consumer products. Such environments may include
hones, day-care facilities, and schools where asbesr.os-containing construction
and insulation materials (especially sprayed-on materials [3_j and possibly
floor tiles (48J) may be deteriorated, friajle (easily crumbled), or otherwise
likely to result in fallout (e.g., from frequent mechanical disruption).
Asbestos was used extensively in school and other construction from 1946 to
1978 (4-7).
Between 1969 and 1970, concentrations of asbestos in ambient (outdoor) air
were measured in 48 cities in the U.S.A. Asbestos was detectable in the air
of virtually every metropolitan area; however, ambient levels never exceeded
100 ng/ta^ (about 3,000 f/m^—see footnote on page 3 concerning the use of
a conversion factor of about 30 f/ng) , except near sources of asbestos
emissions (e.g., within 0.5 miles of an ongoing asbestos spray fireproofing
operation where levels as high as 500 ng/nH—about 15,000 f/nr—were
measured) (4_p. In the homes of chry30tile asbestos mine and mill workers,
five (382) of thirteen 4- to 8-hour daytime air samples contained between 20U
and .5,000 ng/m^ (about 6,000 to 150,000 f/m^), whereas airborne asbestos
concentrations in the homes of nonminers in the same town were routinely less
than 100 ng/m^ (about 3,000 f/m^) (£l_). In 10 public schools, evaluated
because of visibly damaged areas of sprayed-on chrysotile asbestos, the
airborne concentrations in 4- to 8-hour daytime indoor samples ranged from 9
to 1 ,950 og/m^ (270 f/m^ co 60,000 f/m^), with an average of about 220
ng/m^ (6,600 f/m^), whereas outdoor samples at three of these schools
averaged 14 ng/m^ (420 f/m^) (41). A more representative, random survey
of 25 schooLs with asbestos surfacing materials gave similar results, even
though these schools were not selected because of the presence or absence of
damaged materials. In that survey, average levels of about 240 ng/m^ (7,200
f/in^) were found in rooms with asbestos surfaces, 54 ng/m^ (1,600 f/m^)
in rooms that were in the same buildings but that did not have asbestos
surfaces, and 8 ng/m^ (240 f/m^) in sasiplas of air outside these buildings*
Or. the basis of a survey of the nation's schools, EPA estimated that as of May
1982 about 8,600 schools contained friable asbestos (_!_). Although recognizing
various limitations to the validity of these data, Nicholson has escimated
that about 2 to 6 million students and 100,000 to 300,000 teachers,
administrators, and other staff, including approximately 23,000 janitorial and
maintenance workers, are potentially exposed to airborne asbestos in these
schools (8,41).
Environmental asbestos exposure may increase the risk for preventable
premature mortality due to lung cancer (beyond the proportion that could be
attributable to other nonoccupational exposures such as cigarette smoke and
ionizing radiation) and mesothelioma (30,31,34 ,45). In the absence of
population-based data for nonindustrially exposed groups, EPA and others have
7
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provided iadirect estimates of the general population risks by means of
quantitative risk assessment aethods (8,30,31,34,41,45).
Using a ncaber of controversial but explicit assumptions, EPA has estiaated
that over the next 30 years about 1,000 premature deaths (minimal and maximal
estimates <=> 100 and 7,000) will result from current and future exposures to
aobsstoo roleased from friable building materials. Although an estimated
excess lifotima riok of 1,000 premature deaths per 90,000,000 person-years (30
ycaro of oirpoaura for on average population aizu of 3 million people) may not
~com to represent an unuaually large individual risk ratio, EPA regards this
aa en important national public health problem, especially since 90% of these
deaths would be expected to result from children's exposures that could have
been prevented (8,41).**
The assumptions used in the EPA risk aaaaosment Included the following:
reference exposure and epidemiologic data from mortality studies of
asbestos-exposed insulation workers; estimates of the prevalent levels of
airborne asbestos exposures in schoola containing friable asbestos from data
on buildings surveyed in European and American cities; the extent of
contamination and size of the populations at risk, from the above-mentioned
survey of U.S. schools in which asbestos was considered a potential hazard
only If it was friable; no change in smoking heblts (assumed to be the same as
those of the reference population of insulation workers) over the next 30
years; an extrapolation of four orders of magnitude, from the exposure levels
experienced by the insulation workers, with no consideration given to the
Influence that children's longer life expectancy would have on the risk for
mesothelioma; and no peak exposures over the estimated mean levels (8_). An
additional assumption was that the cumulative exposures for 3.2/ million
current, school occupants (about 90% students) were calculated as if they were
a cohort that would be exposed for 1,000 hours per year (students) or 2,000
* The rule on asbestos hazards in schools was partly justified by EPA because
of the need to control "peak" exposures (_1_). In buildings containing
friable asbestos materialst peak exposures of up to 500,000 ng/m^
(15,000,000 f/m^) have been documented and may be common during simple
maintenance or cleaning operations or aftej vandalism and other damage
(1,8,41). The average adult male inhales about 9.6 m^ of air per 8 hours
of light physical activity, and the average 10-year-old child inhales about
8.24 in the same period of light physical acrivity. During periods of
rest or maximal exercise, the volume cf inspired air may be about one-third
or five times the given values, respectively (49). A "school year" of
exposure is about 1,000 hours (6 hours per day for 5 days per week and 33
weeks per year), whereas a "work year" of exposure is about 2,000 hours (8
hours per day for 5 days per week and 50 weeks per year). With these
factors in mind, it l.s important to note that a peak childhood exposure to
500,000 ng/m^ (15,000,000 f/m^) for 1 hour results in inhalation of the
same number of fibers as exposure to 500 ng/m^ (15,000 f/m^) over a full
school year. Since adult school workers inhale about 502 more air at
similar levels of activity and are exposed to the school environment for
about twice as many hours per calendar year as students, they would inhale
the same number of fibers at about one-third the peak or annual exposure
levels given in the example for children.
8
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hours per year (otaff) over the 30-year period chat the school buildings are
czpacted to reaaic In service (8_K Although EPA recogniied that over this
tiae the current students and staff would be replaced by others, the agency
won able to simplify its risk estimates by assessing that the oiie of the
expound population would resiela at obout 3.27 oillion, by using cunulatlve
coipooureo, and by asouaing a linear aonthresbold duse-reopoaoo relationship
(8,30,34,45).
flora cautious aeoumpciona (e.g., the occurrence of peak crpotureo
and the use of a tiae-dependene dosc-res7>on3e aodel) , which reflect the
greater magnitude of s«3otheliocia risk for exposed children, would
considerably increase tha above rink ectimatos.
THE RATIONALE BEHIND EPA'S SCHOOL ASBESTOS HAZARD PROGRAM
EPA's attention to controllable environmental sources of asbestos exposures
has been focused on the relatively greater {wtential risks for children than
for adults partly because children are core active, they breathe at higher
rates and more often by taouth, they spend aore time close co the; floor where
sedimented duat accumulates, and they have an anticipated longer remaining
life span during which the chronic effects of asbestos exposure may be
manifested (_2-8.).
The EPA policy assunes: ,1) that valid and reliable methods of inspection,
sample identification and collection, and analysis will be used by adequately
trained individuals to detect the presence of bulk asbestos in school
environments, 2) chat evaluation criteria based on such data will permit &
quantitative estimate of the hazard potential for deterioration, disturbance,
fallout, and resuspension of airborne respirable-size fibers, 3) thac 3uch
criteria may be used for selecting tha most appropriate control strategy among
several alternatives thac vary in effectiveness and technical and economical
feasibility, 4) that implementation of such concrol measures will
significantly reduce the overall lung burden from environmental exposures to
asbestos fibers in school populations, and 5) that such a reduction in lung
burden will significantly reduce the risk for delayed onset of
asbestos-associated cancer in these populations. However, regardless of the
logic behind the program, EPA has proposed no means for evaluating the
effectiveness of its implementation, and preliminary evidence indicates that,
in practice, program operations will vary markedly (12,50). We know of only
two States (South Carolina and Arizona) in which tfte State health department
has prescribed and administered the training, certification, and methods to be
used in each school asbestos hazard evaluation (51 ,52).
ENVIRONMENTS AFFECTED BY EPA'S RULE
The mandatory EPA rule calls for an asbestos hazard evaluation in all
nonprofit public schools. More details on the legal definitions of
"nonprofit," "public," and "schools" may be obtained from the rule itself (_1_) •
The EPA rule does not mandate an evaluation of asbestos hazards in other
indoor or outdoor environments.
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THE MANDATED PROCESS OF INSPECTION, IDENTIFICATION, AND NOTIFICATION
The steps involved in complying with the EPA rule consist of three phases:
inspection, identification, and notification (13). The iopleaentation of
control measure* is not mandated. Certainly, ethical and legal issues Bay
arise when potentially hazardous asbestos-containing materials are found in
the school environment (1,16,21,33).
In the following outline of the required process, sone suggestions are
included that, although not required under the letter of the rule, appear to
be appropriate:
1.	Inspect che entire school building for deteriorated, water-damaged,
or frMble material that say contain asbestos and be subject to
fallout or mechanical disruption (6,5,11,13).
2.	If such material is found (e.g., on floor or ceiling tiles, in pipe
lagging, in sprayed materials, or on jackets of boilers or furnaces),
take systematically selected random bulk samples by removing all
layers of three or more representative portions of the material with
a suitable sampling device (e.g., a scalpel or trephine) and putting
them into a clean collecting device (e.g., a 35-mm film canister).
Use appropriate respiratory protection and work practices when
obtaining the samples to minimize potential personal and
environmental exposures to asbestos fibers.*
3.	Carefully label each container to show the sampling site, and submit
the samples to a competent laboratory to determine if they contain
asbestos. Specify the preferred analytical method (polarizing light
microscopy with dispersion staining or electron microscopy), and
require that the laboratory report its findings with quality control
data on the sensitivity, specificity, limits of detection, possible
interferences, and confidence limits of quantitation for the method
a8 used in that laboratory.
4.	Evaluate the potential for human exposure "if the presence of asbestos
is confirmed, using a standardized set of evaluation criteria that
include the condition and type of product, the likelihood of water
damage, the accessibility and amount of exposed surface area, air
movement in the vicinity, human activity in the vicinity, friability,
the number and age of occupants, the average duration cf occupancy,
* To provide advice on sampling and analyses, including a list of laboratories
that are competent m the polarized light microscopic method of analysis,
EPA maintains a toll-free telephone number: 1-800-334-8571. EPA has
advised that in the process of obtaining samples of random or suspect
building materials, respiratory protection is unnecessary, although
exposures of up to 100,000 f/m3 may occur during sample collection (_1).
However, we believe that the use of personal respiratory protection and
precautions against releasing fibers to the environment during sampling
(such as enclosing and wetting the surface area to be sampled) would be
prudent.
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che frequency and methods of cleaning the exposed surface, and the
percentage of various types of asbestos in the material, by weight
(13).
5. Post warnings as prescribed by EPA, and notify potentially exposed
teachers, custodians, other staff, and parent-teacher associations of
the findings and any recommended control measures.
IDENTIFICATION AND EVALUATION OF ASBESTOS HAZARDS - SOME CAVEATS
In Industrial Occupational Settings Where Asbestos Is Known To Be Present - In
the mining, milling, formulation, or application of a product that is known or
suspected to contain asbestos, the hazard's recognition, evaluation, and
control depends on the sampling and analysis of airborne respirable-size
asbestos fibers. Fibers less than 3.5 ,11m In diameter are considered
respirable (15).
The Occupational Safety and Health Administration (G3HA) standard for
occupational exposure to airborne asbestos is based on the concentration of
fibers that are longer than 5 micrometers (jum) and are thus resolvable by a
400-500 X magnification phase-contrast microscope (PCM) (53). Since 1976, the
OSHA standard has limited a worker's 8-hour time-weighted average (TWA)
exposure to 2,000,000 fibers (longer than 5 ,um) per m^ (f/m^), In
December 1976, NI0SH recommended to OSHA that this standard be lowered to
100,000 f/m"^ (8-hour TWA) (15). In November 1980, the 100,000-f/m^ limit
was selected by NIOSH again on the basis of the best available data concerning
health risks and the validity and reliability of available methods for
sampling and analyzing airborne asbestos fibers (19). Because of the
well-docunented human carcinogenicity of asbestos and the apparent lack of any
threshold (no-effect level) in its carcinogenic effects, NIOSH's ultimate goal
in recommending occupational exposure limits has been to eliminate asbestos
exposure. Although the 100,000-f/m3 limit was considered not feasible,
partly because of the limitations imposed by currently accepted methods of
sampling and analysis, NIOSH's recommendation was intended to 1) protect
against the noncarcinogenic effects of asbestos, 2) materially reduce the ri.-.k.
of asbestos-induced cancer, and 3) be measurable by techniques that are valid,'
reproducible, and widely available to industry and to official agencies (19).
In November 1983, OSHA issued an emergency temporary standard that would have
lowered the worker's 8-hour TWA exposure to 500,000 f/m^. This emergency
standard was suspended by judicial order (November 23, 19S3) , and the limit of
2,000,000 f/m3 is the current OSHA standard for occupational exposure to
airborne asbestos. In June 1984, NIOSH reiterated its recommendation for an
occupational exposure limit of 100,000 f/m3, noting recent improvements in
the sensitivity and reliability of available methods for sampling and
analyzing airborne fibers (54,55).
Some researchers believe that asbestos fibers less than 5 pm long may be
carcinogenic and that they should be included in the airborne fiber count;
however, only supplemental use of the more expensive and sophisticated
analytical EM methods would permit detection of such short fibers. Other
investigators believe that the main hazard is from asbestos fibers longer than
L0 co L5 urn (those chat cannot be fully ingested by single c.^lls in the lung).
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Still other investigators have hypothesized that any durable mineral fiber
0.25 ;um or less in diameter and longer than 8 jjm may be capable of inducing or
promoting carcinogenesis if inhaled (56-58). The portion of very short or
very long fibers in the total weight of fibers collected by air sampling
varies greatly (15,30,34).
Clearly, the sensitivity of the method for identifying airborne asbestos
depends on whether PCM or EM methods are used and on whether the distribution
of fibers by size and the absolute fiber count are determined.
Of more fundamental concern is the fact that the PCM analytical method used
under the OSEA standard for airborne asbestos is not specific for asbestos
fibers. This may aff -.t both the sensitivity and the specificity of the
method. Under OSHA's standard, fibers are identified only by the requirements
that the observed particulate must have a length-to-diameter (aspect) ratio of
3:1 or greater and be detectable by PCM methods. The physical, chemical, and
mineralogical nature of the material need not be determined. Thus, glass
fibers or other refractile fibrous minerals may be counted (false positives),
and asbestos fibers or fibrils too small to be detected by light microscopic
methods may not be noted (false negatives) (19).
In Nonindustrial Settings (Such as Schools) - There are no uniformly accepted,
standardized evaluation criteria (at least seven algorithms have bean used)
for predicting the aerosolization potential of respirable fibers from
asbestos-containing bulk material (12,13). State health departments have only
limited economic, human, and technical'resources available for evaluating the
hazards of nonoccupational exposures to asbestos and other indoor air
pollutants (59). In practice, some or all of the factors (listed in item 4
under the previous section) are scored for each sample analyzed; the total
scores for each sample are then compared with predetermined criteria so that
the relative hazard potential of each sampling site can be rated (10,12). The
latest EPA guidance document (13) suggests the use of "yes" and "no" responses
rather than a scoring system, thus reducing ambiguity; however, that method
has not been independently evaluated (12).
Considerable controversy surrounds the adequacy of the PCM light microscopic
method's sensitivity and specificity for identifying asbestos fibers in air
samples; howevar, in bulk samples the use of a light microscopic method may be
sufficiently sensitive (the size of fibers is not likely to limit detection)
and specific if polarizing light microscopy (FLM) or PLM in conjunction with
dispersion staining is used in a laboratory with good quality control (15).A
* Advice on the results of quality control tests by various laboratories may
be obtained from £PA by telephone (1-800-334-8571). The cost of analyses by
light microscopic methods varies from about $25 to $45 or more per sample.
The cost of analyses by EM methods varies from about $100 to several hundred
dollars per sample.
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When air samples are collected (e.g., during routiue periodic monitoring of an
environment containing potentially hazardous bulk asbestos materials or after
an asbestos abatement or removal program), the "action level" should conform
with a policy of lowest feasible level.*
Use of the revised NIOSH PCM air sampling method, including modified rules for
counting only fibers with aspect ratios of 5:1 or more in a 1,000-liter sample
of air, will permit detection and quantitation of about 10,000 f/n^ if a
coefficient of variation of about 252 is considered acceptable for risk-
management decisions (54 ,55,60). This variability is reasonable, since the
conversion factor (30 f/ng) used to convert mass concentrations to fiber
concentrations in environmental risk assessments has such a large uncertainty
factor (250 f/ng). An "action level" of 10,000 f/m^ may be useful as a
guideline for monitoring a building with potentially hazardous asbestos
surfaces as part of a comprehensive asbestos program or during abatement work,
maintenance, etc. It is not a recommended "occupancy" or "safe" level.
Studies of occupational groups have shown no clear evidence that comparable
exposures to different asbestos fiber types or formulations rssult in
different levels of risk for asbestos-associated cancers (34). Only
analytical EN and PLM methods can distinguish the specific mineralogical types
of asbestos (15). When the revised NIOSH exposure monitoring method is
applied to environmental settings, about 5% of the air samples below 10,000
f/m and all of the samples that contain more than 10,000 f/m should be
further analyzed by EH or PLM methods for specifically determining the
identity of fibers detected by the PCM method (54,55,60).
Investigators at NIOSH have developed a screening test for asbestos, the
method (a colorimetric test interpreted visually by the investigator), which
may be used in the field. It is extremely sensitive (61); however, recent
experience indicates thai; false-negative results can occur with materials
containing more than 1% asbestos (62). Since the specificity of a screening
test is of considerable importance in determining the predictive value of a
positive test, it is important to note that false-positive results are common
with the asbestos screening test. Thus, positive samples must be
confirmed by analytical EM or PLM methods (62). In a stratified random sample
of Colorado schools, in which the method of dispersion staining with PLM was
used for confirming positive tests, the specificity of the test was
only about 21% (28). Under these circumstances, the predictive value of a
positive test was only about 56% (28,62). The test probably should
not be recommended for use as ~ screening test (62).
An algorithm developed for risk assessment of asbestos in the Colorado schools
identified 31 of 41 randomly selected schools that had asbestos material in
* The concept of an environmental "action level" is not the same as that of a
permissible exposure limit that is precisely monitored for compliance with
regulatory standards. As used here, it is consistent with CDC's policy of
recommending that asbestos exposures be reduced to the lowest feasible
level; it is readily measured by using the revised NIOSH PCM method (54);
and it should be helpful to authorities who must make risk-management
decisions when the general public is potentially exposed to a
well-documented human carcinogen.
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one or more locations, and most of these had high exposure potentials, on the
basis of relative scores for six evaluation criteria: condition or degree of
deterioration of the material, its accessibility, air movement, human
activicy, friability, and percentage of asbestos. For each sample site, each
criterion was ranked 1 to 3, except the percentage of asbestos, which was
ranked 1 to 4. A score of 8 or less was considered a negligible hazard, and
9 or more indicated that the site required corrective action (28,62).
On the basis of these studies, 63Z-892 of the public schools in Colorado were
estimated to pose a potentially serious asbestos hazard to staff, children,
and community groups who use these schools (28). This is about two to three
times the national average estimated from EPA's survey (_8); however, this
average may reflect differences in the sampling and analytical methods and
evaluation criteria of the "Colorado algorithm" rather than in the actual
prevalence of hazardous asbestos problems at schools in Colorado (12).
NOTIFICATION: THE LEGAL PROCESS AND AN OPPORTUNITY FOR EDUCATION AND RISK
REDUCTION
The principal legal requirement appears to be that potentially exposed
occupational and nonoccupational school occupants should be notified that
friable asbestos has been identified in their school. There is no mandate to
provide the occupants with a quantitative estimate of their risk for
asbestos-associated diseases. Such " estimate would be very difficult to
make, since valid and reliable dat, .i levels of exposure based on
air-sampling are difficult to obtain in these settings.
The only other legal requirement appears to be that school employees should be
notified of OSHA requirements (i.e., for training, supervision, protective
equipment, monitoring, and medical surveillance) if the asbestos is removed or
if their tasks result in more intense occupational exposures..
From a public health perspective, potential exposures to low levels of
asbestos in nonindustrial settings may be less important than exposures to
cigarette smoke (in relation to one's ultimate risk for premature morbidity
and mortality). Therefore, when a potential asbestos exposure hazard is
identified, the notification to the school should be accompanied by
information on the numerous benefits of not smoking, including the reduced
synergistic risk for lung cancer due to historical or future exposures to
asbestos. It should be made clear, however, that no such benefit has been
demonstrated for reducing the risk of pleural and peritoneal mesothelioma and
that exposure to asbestos may carry a risk of lung cancer even for nonsmokers.
CONTROL MEASURES - HEALTH AND EC0M0MIC„IMPACT OF THE EPA RULE
The rule does not mandate that corrective or control measures be taken if a
potentially hazardous exposure to asbestos is identified; however, EPA's
regional offices can provide technical information and perhaps assistance
regarding control measures. Advice and technical assistance to workers and
their supervisors called upon to implement control measures may also be
obtained from NIOSH or OSHA regional offices. This advice may include
engineering controls, exhaust ventilation, work practices, personal protective
equipment such as adequate respiratory protection, and medical examinations.
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In selecting the most appropriate control measures, school officials should
consider the following factors:
1.	The location and amount of the asbestos-containing jaterial(s).
2.	The condition and function of the material(s).
3.	The likelihood of present or future fallout or disruption of the
iaaterial( 3).
4.	The economic cost, technical feasibility, and potential for
hazardous occupational versus nonoccupational exposures in the
course of various control measures.
The alternative control methods are as follows (13):
1.	Encapsulation (with an effective sealant) reduces the likelihood
that fibers will be released into the building environment as long
as the sealant remains intact. If this method is used, a
comprehensive asbestos hazard program should be instituted on the
basis of current OSHA regulations and NIOSH recommendations, buch a
program should include the designation of one competent
administrator who would be responsible for organizing and conducting
routine periodic inspections and environmental monitoring (using the
lowest feasible action level, e.g., 10,000 f/m^); education and
training of potentially exposed individuals; respirator selection,
maintenance, and use; and recordkeeping.
2.	Enclosure (with a barrier such as a suspended or false ceiling)
reduces the likelihood that incidennl contact with the
asbestos-containing material will occur as long as the barrier
remains intact and entry into the enclosed space is not required.
If this method is used, a comprehensive asbestos hazard program, as
described above, would be advisable.
3.	Administrative management may effectively minimize the problem if no
action is required immediately and if potential sources are
inspected periodically. If this method is used, a comprehensive
asbestos hazard program, as described above, would be advisable.
4.	Removal eliminates the source of the contamination. However,
control by removal nay cause considerable exposure risk for workers
and for future occupants unless disrupted material is removed
properly and completely, appropriate work practices are used, and
respiratory protection is provided.
Under the EPA rule, it is not necessary to follow up the positive
identification of a potentially hazardous exposure to bulk asbestos with a
demonstration of airborne respirable asbestos fibers in the affected
environments). In fact, a comprehensive evaluation (sampling and analysis)
of airborne asbestos concentrations—even in a relatively circumscribed
environment—is very costly, and highly sophisticated human and technical
resources are required to obtain valid results. Furthermore, in a given
sampling only the current airborne fiber concentration is measured, and thus
the risks for transient and peak exposures due to episodic releases of fibers
from bulk material are not reflected.
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Since che financial and human costs of any control aeasure aay be high, the
avoidance of a false-positive identification of an asbestos hazard is an
important consideration in implementing a program to comply with the EPA rule.
In August 1984, the Asbestos School Hazard Abatement Act of 1984 established
an EPA program to provide financial assistance to local and State aducational
agencies that have identified sources of asbestos that ar« potentially
hazardous to the health of schoolchildren and employees. This fall, EPA will
send an informational package uc the office of each State Governor concerning
plans for implementing this Act. Application forms will be sent directly to
the local educational agencies to be completed. These applications will be
processed by the State, and EPA will assign priorities on the basis of the
nature of the asbestos hazard and rhe financial need of the affected school.
EPA's review and evaluation vill determine who receives financial assistance.
Since funding is limited. EPA strongly encourages local educational agencies
and State governmental officials to begin abatement efforts and not delay or
revise plans in anticipation of federal assistance. For further information
on this Act, contact your EPA Regional Asbestos Coordinator as provided in
this advisory.
RECOMMENDATIONS
The primary prevention of hazardous exposures to toxic agents is one of the
goals that the Surgeon General identified in his 1930 report titled "Promoting
Health/Preventing Disease: Objectives for the Nation." The early
identification, evaluation, and control of occupational and nonoccupational
exposures to previously unrecognized asbestos is consistent with these goals
and should provide important public health benefits for the nation.
State health departments may be called upon to assist local and State
educational agencies in implementing EPA's efforts to meet these goals. In
addition, States aay wish to identify and control other potentially hazardous
asbestos exposures in environments and consumer products not covered under the
EPA school asbestos hazard program. We hope that the preceding information
and the following suggestions will be helpful in designing and conducting such
efforts.
1.	Standardized reliable and valid methods of asbestos hazard
evaluation are necessary, especially if there is to be periodic
reevaluation of asbestos hazards and an overall assessment of the
effectiveness of the EPA rule (34,45,50,59).
2.	Risk-management decisions regarding the implementation of
alternative control measures for identified nonindustrial asbestos
hazards should be based on an environmental carcinogen policy of
control at the lowest feasible level (12,13).
3.	EPA has announced that it will reevaluate the current regulation
"Asbestos; Friable Asbestos-Containing Materials in Schools;
Identification and Notification" (_1). We recommend support of tnis
reevaluation and any potential efforts on the part of the EPA to
develop uniform methods for surveillance of school asbestos hazards
and to develop uniform criteria for conducting remedial activities.
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4.	In selected settings where the potential for study exi3ts, the
effectiveness of alternative control measures should be evaluated in
relation to the level of hazard determined by a set of standardized
evaluation criteria. Effectiveness may be defined either in terns
of assessing airborne asbestos concentrations in selected buildings,
following cohorts of building occupants *
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indoor, nonoccupational exposures Co asbestos. Assistance nay also be
obtained from the Consumer Product Safety Commission's regional offices or
from those of the EPA. The EPA Regional Asbestos Coordinators' addresses are
listed in Appendix B of the enclosed document, "Guidance for Controlling
Friable Asbestos-Containing Materials in Buildings."
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42.	Churg A, Uarnock ML. Analysis of the cores of asbestos bodies from
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Bernstein RS, Falk H, Turner DR, Melius JM. Nonoccupational exposures to
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H/g Assoc J 1981;42:198-201.
Baldwin CA, Beaulieu HJ, Buchan RM. Application of the asbestos
screening test in Colorado schools. An Ind Hyg Assoc J 1982;43:602-4.
Glickman LT, Domanski LM, Maguire TG, Dubielrig RR, Churg A.
Mesothelioma in pet dogs associated with exposure of their owners to
asbestos. Environ Res 1983;32:305-13.
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