Document 8RyBjrx1a2vZJ4RyQ3aEdym4K
AIR POLLUTION SECTION 3
ANTIKNOCK COMPOUNDS AND PUBLIC HEALTH
0019214
ANTIKNOCK COMPOUNDS AND PUBLIC HEALTH
Q -l: A -l:
A re smog and air pollution the sam e thing?
No. You can have air pollution without sm og, but you can 't have smog without a ir pollution.
Q -2: A -2:
Is the p re sen c e of lead in the atm o sp h ere a phenom enon of the autom obile age?
D efinitely not. W e've alw ays had lead in the a ir, originating from m any so u rc es. The soil, for exam ple, has lead in it ranging up to 15 o r m o r e p a r t s p e r m illi o n . T h e c o m b u s t io n of o t h e r f u e l s , including coal and even wood, re s u lts in the d istrib u tio n of the lead that exists in these fuels into the atm osphere.
Q -3: A -3:
What is the connection betw een antiknock compounds and questions of public health? `
A fter an antiknock compound has done its job of controlling com bustion inside an autom obile engine, the w aste products of the antiknock compound a re discharged through the automobile tailpipe and p ra c ti cally all fall to the ground. A sm all portion of th ese w aste products en ters the atm osphere. Consequently, the question is ra ise d from tim e to tim e as to w hether this lead in the atm o sp h ere is a h azard to public health.
Q-4: A -4:
Have the public health asp ects of antiknock com pounds been investigated?
T etraeth y l lead, the p rin cip al antiknock com pound in u se, has been one of the m o st com prehensively studied of indu strial pro d u cts, from th e s ta n d p o in t of p u b lic h e a lth , in th e l a s t 35 y e a r s . T h is w o rk h a s included two in v e stig a tio n s s p o n so re d by the U. S. P u b lic H ealth S e rv ic e in 1925 and again in 1959. It has a lso included y e a rs-lo n g investigations by the K ettering L a b o ra to ry in the M edical C ollege of the U niversity of C incinnati, under the financial sponsorship of the m a n u fa c tu re rs and d istrib u to rs of antiknock com pounds in the United States. It has also included an extensive study of leaded gasoline, from the standpoint of sm og, conducted by the M idw est R e se a rc h Institute a few y e a rs ago. The re su lts of these and other investigations have been published in scientific and m edical journals. (Continued on P ag e 2. )
Q -5: A -5:
M o st r e c e n tly the U. S. P u b lic H e alth S e rv ic e and. th e C a lifo rn ia D epartm ent of Public H ealth, cooperating w ith industry, c o m p le te d the " T h re e -C ity Study" fo r the p u rp o s e of 1) E s t a b l i s h i n g a b a s e l i n e of l e a d c o n te n t in th e a t m o s p h e r e s a n d in the blood and u rin e of s e le c te d p o p u latio n g ro u p s; 2) A s c e rta in d ifferen ces in lead level for the blood and u rin e of groups exposed to v a ry in g a m o u n ts of le a d , and 3) O b tain d a ta to p e r m i t a r e v ie w of the effects of a tm o s p h e ric le a d on th e population. What have these investigations shown?
These investigations have repeatedly shown the following:
1. T h e l e a d c o m p o u n d s d i s c h a r g e d in th e e x h a u s t of a u to m o b ile engines have not created a public health hazard.
2. A ntiknock com pounds do not contribute to the form ation of smog.
3. The c o n c e n tra tio n s of le a d (fro m a ll s o u r c e s , including a n t i knock com pounds) generally found in the a ir of A m erican cities a re low.
4. The am ounts of lead to which the g en eral population is exposed (from all so u rces, including foods and beverages) are well below hazardous lim its.
5. In the p a st tw enty-odd y e a rs , th e re has been no d e m o n strab le change, on the p a rt of the average A m erican, either in his intake and output of lead, or in the am ounts of lead retain ed in his body.
Q-6: .A6**
Q -7: A -7:
A re any cu rren t investigations underway?
L e a d i,s b u t one of m a n y a i r - b o r n e i n g r e d i e n t s now b e i n g m e a s u r e d on a continuing b a sis by the N ational A ir Sam pling N etw ork.
Do antiknock com pounds play any significant role in a ir pollution?
No. A fter well over th ree decades of sustained use in gasoline, rep eated investigations have failed to dem o n strate that lead antiknock com pounds c re a te h azard s to public health or contribute significantly to the general problem of a ir pollution.
Q-8:
Do antiknock com pounds play any ro le in the fo rm atio n of sm og?
A -8:
No. The M idw est R esearch Institute study, whose findings w ere re p o rte d to the A ir Pollution C ontrol A ssociation in Los A ngeles, d e m o n strate that te tra eth y l lead, the p rin cip al antiknock com pound in use, does not contribute in any m anner to any of the m anifestations
of smog.
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Q -9: A -9:
If antiknock com pounds a r e n 't to b lam e for smog,, why a re so m any fingers pointed at them so often?
The answ er is sim ply that ch arg es a re m ade from tim e to tim e without any scientific foundation or b asis in fact.
Q -10: A - 10:
A re antiknock com pounds the only sou rce of lead in the atm o sp h ere?
No. Antiknock compounds contribute only a portion of the total am ount of lead p a rtic le s found in the atm o sp h ere. O ther so u rces include the com bustion of wood, co al and vegetable m a tte r; lead in the soil; industrial p ro c e sses involving the use of lead; and m an-m ade products containing lead.
Q -ll:
A -ll:
How m uch lead in the atm o sp h ere com es fro m auto exh au sts?
A s sta te d b e fo re , an tik n o ck com pounds acco u n t fo r only a p o rtio n of the total am ount of lead in the atm o sp h ere. It would be ex trem ely difficult to e x p re ss this in exact p roportions because of the v ariab ility of other factors.
Q - 12:
A - 12:
Is the am o u n t of le a d in the a tm o s p h e re , fro m a ll s o u rc e s , of hazardous proportions?
No. R ep e a ted in v estig atio n s have show n th a t the am ount of lead in the atm osphere, from all so u rces, is well below hazardous lim its. The re c en tly completed T h re e -C ity Study has shown that the average concentration of lead in the atm o sp h ere in these cities was 3 m ic ro g ra m s o r l e s s p e r c u b ic m e t e r . T h e s e c o n c e n t r a t i o n s c o n t r a s t w ith th e ............ concentration of 200 m icro g ram s per cubic m eter which has been accepted in the United States as the satisfacto ry specification of the safe co n cen tratio n of lead in the a ir of in d u stria l e sta b lish m en ts. (This specification is not d ire c tly applicable to the g en eral atm o sp h ere because the occupational exposure to lead is approxim ately 40 hours p er week, w h ereas the concentration of lead in the g eneral atm osphere co n tin u es 24 h o u rs p e r day o r 160 h o u rs p e r w eek. )
Q-13: A - 13:
Does increased usage of leaded gasoline m ean a proportionate increase in le a d -in -a ir concentrations in m etropolitan a re a s ?
No, indeed. An extensive study of a tm o sp h eric lead in C incinnati shows p recisely the opposite. The Cincinnati study shows there has
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been a significant reduction in the lead content th ere since the late 1940's. This is tra c e a b le in p a rt to a reduction in airb o rn e lead contributed by the com bustion of coal, and in p a rt to changes in the c o m m e rc ia l activ ities and traffic p a tte rn s in C incinnati during that period. This reduction took place despite the p ro g ressiv e increase in vehicular traffic and in the consum ption of gasoline.
Q - 14: A - 14:
If antiknock com pounds w e re elim in ated , would that not g reatly red u ce the am ount of lead in the a tm o sp h ere ?
Any such re stric tio n s would not elim inate lead from the atm osphere. In fact, as indicated im m ed iately above in Q uestion 13, th e re m ight be little m easurable change of the lead -in -air content.
Q - 15: Q - 15:
A re the w aste products of antiknock compounds the only air-b o rn e contam inants ?
By no m eans. E very activity connected with our daily life contributes one or m ore contam inants to the general atm osphere.
Q - 16: A-16:
What is m eant by p article size and is it significant in lead absorption?
P a rtic le size is an im p o rtan t co n sid eratio n for .two re a so n s - it d eterm in es the am ount of lead which does not settle out of the air but which rem ain s suspended in the atm o sp h ere, and in addition, it d eterm in es the am ount of lead that will enter the lungs and w ill be retain ed th ere. L arg e p a rtic le s of lead fall to the ground rapidly and a re , th e re fo re , not an a ir pollution hazard. Of those p artic le s that a re inhaled, if they a re la rg e r than 5 m icro n s in d ia m e ter, they w ill be filte re d out of the a ir in the upper re s p ira to ry tra c t and, th erefo re, not reach the lungs. Those p articles that are sm all enough to behave like a gas (a few m icro n s in d iam eter) tend to be exhaled ra th e r than to be retain ed within the lung.
When an antiknock com pound has done this job inside an autom obile engine, its w aste products a re d isch arg ed in the exhaust gas. G enerally speaking, up to 75% of the lead en terin g an autom obile is exhausted. H ow ever, la rg e r lead p a rtic le s fall to the ground. It is only the sm all lead p a rtic le s which rem ain suspended in the atm osphere.
So fa r as the a v erag e p e rso n is c o n ce rn e d , the lcLrger lead p a r tic le s again from all sources - would not be inhaled by a person.
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Q - 17: Do an tiknock com pounds p r e s e n t any h a z a rd to h u m an b e in g s ?
A - 17:
Suitable protection is provided by regulation for all m en who handle antiknock com pound. A ll o th ers a re denied a cc e ss to the m a te ria l. None of th ese protected m en have ever suffered lead poisoning.
Q -18: A -18:
How m uch lead is inhaled and absorbed by the average p erso n ?
The quantities of lead taken into the body from food and drink greatly exceed the am ounts taken in with the a ir in breathing. While the a v e r a g e of a l a r g e n u m b e r of o b s e r v a t i o n s o n t h e h u m a n in ta k e o f .......... lead in food and drink approxim ates o n e-th ird of a m illig ram per day, that taken in, in the a ir, w ithin the 24-hour p erio d m ay be as little as one-tw entieth of that am ount or as m uch, perhaps, as onefo u rth of it, depending upon w h e re and how one sp end s th e h o u rs of the entire day.
Of m o re significance is the am ount of lead absorbed into the body. The absorption from the digestive tra c t is slow and incom plete, s o m e w h a t l e s s th a n 10% of th a t s w a llo w e d u n d e r o r d i n a r y c o n d itio n s being absorbed. On the other hand, that absorbed from the re sp ira to ry t r a c t m ay be a s m u c h as 50%, o r so m ew h a t le s s th an 35%, of th a t which is inhaled.
E xhaustive studies have shown that the output of lead daily from the body of the av erag e p e rso n is so n e a rly equivalent to the total intake daily, that any accum ulation of lead w hich m ay occur over a long p eriod of y e a rs , o r a lifetim e, is too sm all to be detected.
Q -19: A -19:
Is lead which en ters the body th ru inhalation m ore hazardous than that which enters by ingestion?
The m a tte r of danger fro m the ab so rp tio n of lead w ithin ap p ro p ria te lim its of dosage is g re a te r, g en erally , in the c a se of inhaled lead because the absorption is m o re rapid and m o re com plete. How ever, w hen the q u a n titie s involved a r e su fficien tly low th e re is no r i s k in either case.
Q-20: A-20:
W hat is the av erag e lead level in the blood of people? What is co n sidered to be the safe lim it?
This v a rie s som ew hat from p e rso n to p erso n , but averages slightly u n d e r 30 m i c r o g r a m s p e r h u n d re d g r a m s of w hole blood.
The upper lim it of safety is about 70 m ic ro g ra m s .
Q-21: A -21:
W hat is the difference in the significance of lead in blood and lead in urine ?
The answ er to this question m ight b etter com e from m edical people.
Q-22; A-22:
What is the ultim ate te s t of any lead h azard to hum an beings?
The ultim ate c rite rio n of safety , in re la tio n to hum an exposure to lead, is the freedom of the individual from a rate of intake and absorption which will re su lt in the p ro g ressiv e accum ulation of lead in his body over a long period of tim e. All available evidence indicates that, under the p re s e n t g en eral conditions of exposure, no such accum ulation occurs.
The additional evidence which is being sought through future ex p erim en tatio n is intended to define the th resh o ld point in the overall exposure to lead from all so u rces, which will re su lt in a b arely d em o n strab le accum ulation of lead in the body. By such m eans, the m argin of safety betw een p resen t conditions and potentially hazardous c o n d i t i o n s c a n b e e s t a b l i s h e d , a n d a s t a n d a r d f o r th e f u t u r e m a d e ............ available. However, you m ay w ish to develop this fu rth er with m edical people.
Q -23: A-23:
W hat do you m ean when you use the te rm "potential h a za rd "?
A potential h a z a rd is one w hich has the capability of producing a deleterio u s effect and is one w hich produces the possibility of risk . The h a z a rd b eco m es re a d o n ly when som e facto r changes in som e m anner.
O ur p urpose is to avoid any ris k by insuring that the exposure is n ev er sufficiently g re a t, such that it would re s u lt in the accum ulation of lead in the body.
Q-24: Do antiknock com pounds c re a te a public health problem ?
A -24: Q-25:
B a se d on our studies and those of o th ers, th e re is no evidence that antiknocks create a public health problem .
'
A re A m erican s absorbing m ore lead into th eir sy stem s than they used to ?
A-25:
No. A study shows that the a v erag e citiz en , even if re sid in g in a m etro p o litan a re a w ith heavy highway traffic, has shown no m easu rab le in c re a se in the concentration of lead in his blood or in the daily output
o f l e a d in h i s u r i n e d u r i n g t h e p a s t 13 y e a r s .
Q-26: A-26;
Is th ere any connection betw een antiknock com pounds and lung cancer?
We have no ev id en ce th a t an tik n o ck com pounds a r e in any way related to lung cancer.
Q-27: A-27:
A re th ere other toxic m aterials in antiknock compounds besides lead?
T here are other m aterials in a com plete antiknock compound, p rin cip ally chlorine and brom ine. T h ese, in g en eral, a re burned w ith the com bustion of the fuel and occu r in the exhaust gas in low concentrations and of hygienically insignificant proportions.
Q -28: A -28:
Is th ere any connection betw een antiknock com pounds and the death ra te in the g en eral population?
The death ra te in the United States has d e crea se d steadily during the period in w hich the use of antiknock com pounds has been increasing.
Q -29: A -29:
Have com m itm ents to m ental institutions ris e n in proportion to the use of lead antiknock com pounds?
D uring the p erio d in w hich the use of antiknock com pounds in the United S tates has been in creasin g , and p a rtic u la rly in the la st ten y e a rs, th e re has been an in c re ase in the proportion of m ental illness in the A m erican population.
Any relatio n sh ip betw een th ese two phenom ena m u st be re g a rd ed as purely coincidental.
The esse n tial fact is that an in creasin g aw aren ess of the p ro b lem s of m ental health has com e about through im portant advances in the recognition of these diseases by m edical practitioners.
Q -30: A-30:
Is th ere any connection betw een antiknock com pounds and m ental health?
In acute sev ere poisoning by antiknock com pounds, there is a typical and acute fo rm of m ental illness that is com pletely re v e rsib le . This type of poisoning o c c u rs only r a r e l y and th en only a s the r e s u lt of accidental, in dustrial conditions. T h ere is no relationship betw een antiknock compounds and other form s of m ental illness.
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Q-31: A-31:
Does smog cause lung can cer?
> ......
It is not known w h eth er the ch em ical constitu en ts of g e n eral a ir pollution can produce lung can cer. C ancer-producing chem icals have been identified in the a ir, but it is not known w hether they can produce can cer in m an or w hether the concentrations that a re found are sufficient to produce a c an c e r in m an.
,
Q-32: A -32:
I t is r e p o r t e d t h a t a u t o m o b i l e s in L o s A n g e l e s d i s c h a r g e 16 to n s of lead daily into the a tm o sp h ere. Is this tru e ? W hat effect does it have on the public ?
If it is t r u e , it w ould ta k e 3. 5 m illi o n c a r s u s in g s o m e w h a t m o r e th a n 6 m illion gallons of gasoline to do it. T h eo retically , then, it is possible that autom obiles could discharge that m uch lead- although it m ust be rem e m b ered that a good p a rt of the lead falls to the ground. A ctual m e asu rem en ts have shown that the dissipation of lead is quite rapid, both because of rapid settling of the p a rtic le s and the dilution in the atm osphere.
Q-33: A-33:
W hat a r e the a v e ra g e c o n c e n tra tio n s of le a d in the a tm o s p h e re of A m erican citie s? What are the highest reported concentrations? How do they co m p are w ith in d u stria l safety lim its?
As p re v io u sly noted, the c o n ce n tra tio n of lead in the a tm o sp h e re of A m e ric a n c itie s, a s in d ic a ted by the T h r e e -C ity Study, a v erag es 3 m ic ro g ra m s p e r cubic m e te r or le ss. One isolated s a m p l e s h o w e d a c o n c e n t r a t i o n a s h ig h a s 71 m i c r o g r a m s p e r cubic m e te r for a b rie f p erio d of tim e on a heavily tra v e lle d highw ay, b u t e v en h e r e , the c o n c e n tr a tio n s a v e r a g e only 25 m ic ro g ra m s p er cubic m e te r. These atm ospheric lead con c e n tra tio n s c o m p a re w ith a safety stan d a rd of 200 m ic ro g ra m s of le a d p e r cubic m e te r w hich h as been acc e p ted for in d u stria l occupations.
Q -34: A -34:
Why should the public health lim its for lead in the atm o sp h ere be low er than those for industrial occupations?
C hiefly b ecau se occupational exposure is g e n erally lim ited to 40 hours a week, w hereas com m unity exposure under variable conditions is continuous.
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Q-35:
A re the m ore volatile antiknock com pounds, such as tetram ethyl lead, m ore hazardous to public health than tetraethyl lead?
A -35: Q-36:
No. U nder the conditions of use th e re is no evidence of any public
health h azard in eith er case.
^ -~
D idn't a Yale p ro fe sso r once p re d ic t that p ed estrian s would "drop l i k e f l i e s " o n F i f t h A v e n u e in N e w Y o r k C i t y if v e h i c l e s u s e d ............. leaded gasoline?
A -36:
P rio r to the use of leaded antiknock com pounds bn a la rg e scale, dire consequences w ere predicted by a num ber of people, including som e u n iversity p ro fe sso rs in the United States and abroad. These predictions w ere m ade without knowledge of the m anner and extent of the use of these com pounds and of the m any v ariab les that would exert their influence.
Investigations have shown that the actual conditions of use have borne v e ry little re sem b la n c e to those that w ere postulated p rio r to experience.
Q-37: A re enclosed vehicular tunnels and other heavily travelled highways the source of g re a te r concentrations of lead than other a re a s ?
A -37:
The concentration of lead along heavily trav elled highways is higher than that in other a re a s , but the rap id m ovem ent of the atm o sp h ere rapidly dissipates the lead so that highway levels a re not sustained. In vehicular tunnels w here relativ ely high levels have been m e asu re d when com pared to the g en eral atm o sp h ere (average 44. 5 m ic ro g ra m s p er cubic m e te r in the outlet a ir of the Sum ner tunnel), the tunnel em ployees showed no eyidence of exposure.
P r e p a r e d Ja n u a ry , 1965 R e v ise d D e c e m b e r, 1965
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