Document o9ENrQ5B5o6OKm5DL8p4Jg5NX
A Study of the Physiological Effects of Carbon
I l l . .4tisorption and Elutiori Potskitials; Sitbczrtaiizozis Oijcctioirs
CARL A. NAY, M.D.; JACK NEAL, M.S., and V. A. STEMBRIDGE, M.D., G a l v e s t o n , Texos
Carbon black, the finely di\ided carbon The potciitial physiological effects
resulting from the incomplete combustion of tact with these \-arious "blacks
gas, oil, and oil sludges, or mixtures of these studied extensively until in 1949
materials, is becoming increasingly more im- industry initiated an extensive
portant. primarily because of the increasing directed toward studying the possible e
demands for rubber goods in which; in of (1) ingestion; (2) skin contact;
general, carbon black is a significant com- adsorption and elution potentials: sub
ponent. It has been used for many years neous injection; (4) inhalation.
as a coloring for certain foods (jelly beans, The results of the first two
licorice, gum drops, etc.), in inks and in this study were completed and .rep
rubber goods used in food processing (tub- These studies included not only an
ing, conveyor belts, etc.). While all carbon tion of the "whole" carbon black as
blacks are the product of incomplete com- duced and used but also a study of ads
bustion of carbonaceous fuels there are benzene-extractable components (when
many different varieties of "black." There ent) of various "furnacd' blac
are 4 principal processes of manufacture : clition. an evaluation of the adsorbing po 1. The impingement or channel process in which of various furnace blacks for
tine particle (highly a r g l m e r a t e d ) blacks are made entirely from .gas -7. The lamp black process in which a relatively coarse (highly agglomerated) carhon is pro-
,.inogens and the inactivation of such cinogens when adsorbed on carbon b was included.
duced from a variety of oil products 3. The furnace process, using either gas or oil
or both. in which hy v a y i n g the operating conditions, blacks of graded sphere sizes can lx produced 4. The thermal process, in which hydrocarbon
The results of the first two ph sented evidence in support of the that the ingestion of and skin contact various channel (impingement and/or nace) blacks leads to no detect
cases are used to produce c a u s e blacks which from the normal in hamsters,
have relatively little tendency to agglonierate pigs, rabbitsq or monkeys-rega
The generalization holds that all carbon amount of
black ingested
blacks. at the time of manufacture, exist in. a high degree of agglomeration. The dispersion to the tinest state develops only in application.
by the skin and regardless of
time such
is maintained.
The third phase of our study. now c
plete. deals with adsorption ancl elutio
Receiveci ior publication July 25, 1960. Dcpartiiient of Pretentike hfcdirine .iid Public
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Iiossibilitiey ;ind the possible effects (it'sub-.' ;
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Hmltli. Dniwm of 1ntlustri:il H\ciene, Vie Lilt- cutaneoub or intraperitoneal injection of
,
tersit! of Texas Medical Branch
varioub channel or furnace carbon b
This study was supported in part hy Cabot The carbon blacks used for th~.;pha
ctmtiiiental Carbon Cumpan\.
Huher Cor-
poration. Phillip4 Chemical Cornpan!, Sld Richard-
son C.irbon Company, and United C.lrbon Coinpiny,
who proiided not onl? financial aid hut alco tech-
nical assiqtance and advicr
"black33'
i n cOlnnlOn use, regs
of what producer makes them. Their
ertie\ are
and are herein*
gether with nomenclature. re\ iewed.
bonds leading to an "unsaturated" state. The benzene were added to the channel carbor!
oxygen is chemisorbed on the carbon sur- black with the adsorbed benzpyrene in an
face. The amount of oxygen present has an attempt to extract the benzpyrene. The sam-
effect on the properties of the black-the ples were agitated at 2s C and allowed to
more chemisorbed oxygen the greater the hy- set in contact for 30 minutes. The!. were
drophilic property of the black and the more centrifuged and the supernatant liquid was
acidic the water sludge of this black becomes. scanned with the spectrophotometer. No
The properties imparted by the chemisorbed benzpyrene was detected when 8pg. or 9pg.
oxygen are very important to the rubber was adsorbed on 100 mg. of the carbon
industry. The chemisorbed oxygen and hy- black and only small quantities were de-
drogen are termed "volatile matter" and may tected when 10p.g. was adsorbed.
be determined by heating most "blacks" to From these studies it was concluded that
1,200 c.
3pg. of benzpyrene was the maximum that
The ash content of channel black is usu- could be adsorbed on 100 mg. of the partic-
ally less than 0.1% and consists primarily ular channel black used, and that this ad-
of oxides of iron and silica. The ash con- sorbed component could not be extracted
tent of furnace black may be as high as with benzene at room temperature by the
, 1%. This is often due to the mineral con- Falk and Steiner method.
I tent of the quenching water.
Studies were then carried out to see if
The nomenclature and general properties artificial and/or natural gastric juice or hu-
1 are well known to those who are producers man blood plasma would elute some of the
but not so well known to others. It seems benzpyrene adsorbed as described above.
well to present them again herein (Tables Accordingly 2.5 gm. of the channel carbon
1. 1 and 2 ) .
black to which 0.225 mg. of benzpyrene had
Adsorption and Elution Potentials
been adsorbed were added to each of 50 mI. of gastric juice and blood plasma. These
3, 4-Eenzpyrene was added in successive samples were placed in 125 ml. Erlenmeyer
increments to an impingement (channel) flasks which were shaken for 3 minutes
black having 0.0014% of benzene-extract- .I mechanical shaker) out of each hour for
ables. This adsorption was carried out ac- S hours temperature 2s C). They were set
cording to the method of Falk and Steiner.3,` aside for 16 hours and the same procedure
. After preliminary additions of varying was iollowed for 4 successive days. Each
amounts of the 3, 4benzpyrene to 100 mg. sample was then incubated at 37 C for 60
. of carbon black samples it was determined hours and then again shaken for 3 minutes
' that adsorption was almost complete at 1Opg. out of each hour for 8 hours. The samples
per 100 mg. of carbon black. Samples of were then centrifuged at 30,000 rpm. The
8pg., 9pg. and 1Opg. of 3, +benzpyrene supernatant liquid was removed, placed in a
were then added in 10 ml. benzene aliquots separatory funnel and extracted with 10 ml.
to 100 mg. samples of channel black. These o i double-distilled reagent grade benzene.
samples were agitated for approximately The supernatant benzene was removed and
5 minutes each and allowed to remain in scanned with a Beckman D C spectrophotom-
contact over night. The next day they were eter from 290-400 mp. No benzpyrene
centrifuged and the supernatant liquid was was detected-either by using gastric juice
removed and scanned with the Beckman or blood plasma as a potential eluting ve-
DU spectrophotometer for the presence of hicle.
3, 4-benzpyrene. No benzpyrene was de- Samples of lO.Opg., 5.Opg. and 1.2pg. of
tected when Spg. or 9pg. was adsorbed on benzpyrene in benzene were prepared and
100 mg. of the channel black; however, scanned with the spectrophotometer between
minute quantities were present when IOpg. 290-405 mp using benzene as a blank. This
-1.80
1.70-
-1.60
-1.50
1.40 -
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ARCHIVES OF E N V I R O N M E N T A L HEALTH
Benzpyrene Standard Read in Benzene 298 milliniicrons Slit opening 1.7 Du Beckninn IO nim cell
123
4 5 6 7 8 9 10
C u n c e n t r a t 1o n i n \f I r r o L: r R m 3 p e r m 1 1 1 1 1 1 t e r
scanning revealed niaximum absorption at It is to be noted that neither gastric juice
298 nip, minimum at 320 nip and a second nor blood plasma when in contact continu-
and lveaker iiiaximum at 385 mp. Using ously with various channel or furnace car-
concentration in micrograms as the abscissa bon blacks for 7 days elutes any significant
and optical density as the ordinate. a straight component from the "black." These results
line was plotted (Figure).
-are in agreement with the results of our
Control of St.nsitirit?.-Four 2Opg. sam- feeding studies as reported.' These same
ples of benzpyrene were placed in flasks tests were run using gastric juice to which
with benzene. The benzene was evaporated. 10% cooking oil was added. The results
To 2 of the flasks 50 ml. of gastric juice was were the same (negative) as described above
added: to the other 2 flasks 50 ml. of blood when gastric juice alone was used.
plasma was added. These flasks were agitated
for a short time and then set aside at room temperature for 12 hours. Three repeated
Subcutaneous and/or Intraperitoneal Injection
estrnctions in a separatory funnel wing benzene were then made. The benzene was wxnned froin 290-405 mp. It was determined that 60% of the benzpyrene atldetl to the gastric juice and 80% o i that added to the blood plasma could be recovered.
Elution trials were made using gastric
The need for a study of the possible effects of subcutaneous or intraperitoneal contact with various channel and/or furnace carbon blacks is obvious when one realizes that workers handling carbon black may sustain injuries with skin lacerations or
juice and blood plasma and various types abrasions which may permit the entrance
of channel blacks and furnace blacks. The of carbon black into or beneath the skin or
methods used were the same as described into the peritoneal cavity. This "black" may
above.
remain in such areas for many years.
60/'516
Vol. 1,Der., 1960
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material with its small amount of adsorbed (extractable) component, i f present, can be injurious or harmful was not definitely determined prior to these studies.
This phase of our study deals with the
were kept in Monel pans (10 mice to a pan). They were gir+n a liberal supply of Purina Dog Chow to eat (available to them at all times). 411 injected mice were examined carefully for health status and for the
potential physiological effects of the subcutaneous or intraperitoneal injection of the
1. various
and/or 6' furnace"
carbon blacks
2. Carbon blacks from which the benzeneextractable adsorbed components (when present) have been removed
3. The benzene extractives from various
4- The carbon blacks to which the benzene
extractives have been
(after
Prior
benzene extraction)
5. Cotton seed oil in which various car-
bon blacks are suspended to determine
elution potentials of the oil 6. Known free carcinogens (methylcho-
Presence of any detectable masses at the site of injection at least once each week.
Later white rabbits weighing 4 to 5 Ib. were
used for intraperitoneal injection. These
were fed Purina rabbit food and were care-
''fully observed and kept scrupulously clean.
and when a
was detected the
animal involved was isolated and the rapidity with which the mass grew was determined.
When a diameter of 4 cm. for the mass was
attained, the animal was weighed and killed
and all organs and tissues were subjected
to gross and microscopic examination. All
mice were kept for observation until an age of 20 months was reached. Injections
of the various carbon blacks were made,
using water, cotton seed oil, or tricaprylin
as the suspending vehicle.
lanthrene and benzpyrene; not ad- Examination of Table 4 reveals no
significant changes from the normal in mice 7. Known carcinogens (methylcholan- given subcutaneous or intraperitoneal injec-
threne and/or benzpyrene) adsorbed on tions o f various carbon blacks ( furnace-
carbon black
FEF, H A F , SRF, CF; channel-MPC; or
IVhite CFW and brown CaH strain of thermal- IT) with or without an adsorbed
male mice as well as guinea pigs and rabbits component which can be eluted with hot
were used as test animals.
benzene. XOchanges from the normal were
Reference was made in our first report noted in the test rabbits (Table 4). to an adsorbed component (on furnace An oil furnace black (FEF) extracted
black) which could be removed in whole or
in part by continuous extraction of the carbon black for 24 hours with redistilled benzene, using a Soxhlet Extractor. The
amount of this extractable component varies
with the type of carbon black extracted (up to 0.374% in the "blacks" we studied). Extensire studies of the benzene-extractable
,for 21 hours with hot benzene in a Soxhlet
Extractor was then injected free of ex-
tract) ( T 5). ~ ~ ~ ~
It is noted that no significant changes from the normal were observed in the in-
jetted mice.
Subcutaneous injection of the benzene-
reveals the presence of various components -some of which have a carcinogenic effect when painted on the skin of CaH brown mice and CF\V white mice. Consideration
extractables of furnace blacks of types FEF. H.IF and C F when suspended in cooking oil led to the formation of tumors at the site of injection. Suspended in water
of these findings is made a part of our study these same extracts did not cause the forma-
on subcutaneous and intraperitoneal injec- tion o i tumors when injected wbcutaneously Table 6 ) .
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