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Polychlorinated Biphenyl- and Triplicnyl-Incluccd Gastric Mucosal Hyperplasia in Primates
Abstract. Polychlorinated biphenyl or iriphcnyl ingestion by subhuman primates jor J months produced hyperplasia and dysplasia of the gastric n.ucosa. The con centration of the biphenyl within the experimental diet was less than an order of magnitude greater than that occurring in random food samples sold in the United States and less than levels which have occurred in food products as a result of industrial accidents. The increased cellularity, abnormal dyspiastic growth pattern, and invasion of the adjacent tissue region indicate com; romised gastric function and arc suggestive of an eventual neoplastic transformation.
Polychlorinated biphenyls (PCB's) have been widely used in industry for over 40 years as sealants, heat transfer agents, plasticizers, adhesives, and dielec tric fluids in capacitors and transform ers. Global environmental contamina tion (I) and their presence within the food chain have occurred through in dustrial accidents and improper dis posal and misuses of the compounds (2, .?). Polychlorinated biphenyls were reporlcd in the Llniled Stales in coho salmon in J969 and then in mill; fat (2P parts per million), poultry and eggs (4.2 ppm), fish (35 ppm), and cereals (less than 1 ppm) (2). The Food and Drug Administration is presently re moving from the market known con taminated food samples which exceed 5 ppm. However, as a result of occult environmental and food cxposuic, significant levels of I'CH's (over I ppm in adipose tissue) arc present in over 30 pcicem of random samples taken from the general population of this country (4). Two separate, well-documented in dustrial accidents resulted in high con centrations of PCB's in lice oil (2000 to 3()00 ppm), which was subsequently consumed by oscr 1000 people (3). and in fish meal (N to 30 ppm) used for poultry feed (2). 1 lie effects of f'CH's on humans include acneform skin eruptions, pigmentation of nails and skin,, eye discharge, generalized swelling, weakness, vomiting, diarrhea, weight loss, and fetal toxicity (5). Addi tional effects observed in experimental animals fed the compounds include hepatic potphyria in chickens and rab bits (6), proliferation of hepatic smooth endoplasmic reticulum in tats (7), mice, and monkeys (-?), increase in certain hepatic enzyme activities in rats (7) a ml kcsttols (9), neuiopathy in tats (10) , lymphopenia and immunosuppres sion in tabbits and guinea pig- (<). and estrogenic activity in the rat uterus (11) . In the study repotted heie der matologic .'dictations including alo-
pccia, edema, and acneform lesions and hepatic alterations including organ hypertrophy and proliferation of the endoplasmic reticulum were observed in the subhuman primate. In addition, a
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previously unreported lesion, h\ plasia and dysplasia of the vav.n,mucosa, occurred in all animals that were fed diets controlling thy chlorin ated biphenyls and triphcnsls (PCTsh
Male rhesus monkeys raneine in aw from 1V4 to 2 years and having an average weight of 2.9 kg were mod m this study. Six animal-, - ere fed a diet containing 300 parts of PCI! (Aroclor I2-1S) per million and ji\ were given 5000 parts of PCT (Aroclor 5460) per million in the diet, (cr 3 months. The remaining thscc animals served as con trols. During the courre of the experi ment the animals were given access to 400 p of the experimental diet daily. The animals continued to cat through out the experimental period, although there was a decrease in tody weight of approximately 15 percent in both of the experimental groups. Within 1 month, all of the PCH-led animals, and within 6 weeks, the PCT-fcd animals, had hair loss from the head. neck, and luck. A progressive, genctabzcd, subcutaneous edema, particularly of the face, was manifested as swollen cycl'd, ami bps. A purulent discharge exuded from li e eyes, and isolated acneform Icnons were present on skin areas dexold of hair. I.ivet hypetuophy (2.! pcicem of the body weigh.! in contiolv. 4.5 per cent in tire PCI! cioup; 5.6 peice.it in the PCT group) was attributed, mainiv to a proliferation of the smooth endo plasmic reticulum observed electron miejoscopicnlly. I'.dcmaipus thici-cnine of (he stomach wall and marked hyper trophy of the pyloric anJ fue.dic gasttic mucosa occurred.
The hypertiophic gastric muco-a was several times thicker than the control mucosa and was composed of greatly elongated hyperplastic glands contain ing mucus-secreting, celts (Pig. I). 'I he cells containing basilar positioned nuclei, abundant slightly acidophilic cytoplasm, large vacuoles, and a micro villous border abutted on a basal lamina. Prevention of discharge of the secre tion owing to the depth and apposition
Pig. I. (A) Normal pyloric eland- of lb; gastric mucosa (M) arc separated flora the suhmucosn !5) by the mnsruliwix mucosae (in). (It) P'oliow iny polva Hot t-
naied biphenyl Inge:;:ion the hype; 1: f-: is. mucosal glands pci .age the m'ls.'ol :i;:5 nvaiosae lu foim mi .cus-tiP.ed e.vsts o: Kv s-ubmuenso. Celts lining cy-t sum ar to au-a indicated by at mw ( ) ate m: Hod in l-ig. 2. (X-IO ; scale icpresmi- '00 //mb
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of the glands predisposed to the devel
opment of large mucous cysts. Glands
of the fundic area which noinrally con
tain a variety of secretory cell types
consisted primarily of mucus-secreting
cells.
Widespread penetration of the mus-
cularis mucosae and invasion of the
submucosa by the mucosal epithelium
(Frig. 1) was observed in thr stomach
of each experimental animal. Large
cystic areas filled with mucus and
lined with elongated mucus-sccrcting
epithelial cells predominated in the sub
mucosa. Other cells assumed a glandu
lar pattern. Serial sections of the sub
mucosal cysts demonstrated stratified
arrangements of proliferating epithelial
cells which penetrated the basal lamina
and invaded the surrounding connective
tissue of the submucosa (Fig. 2). Epithe
lial oiigin of the stratified cells was
determined by the presence of nucleoli
and similarity of the nuclei in size and
shape to the nuclei of the epithelial
cells lining the cysts. Occasionally, ir
regular hypcrchromic nuclei and pleo
morphic cells with mitotic figutes were
present in the cells of the stratified
areas. The presence of inflammatory
cells in the submucosa in proximity to
the glandulat and cystic changes was
common.
TTie increased ccllulnrity of the
mucous glands with invasion of the
musculaiis mucosae and accompanying
inflammation noted above is histologi
cally described as a hypertrophic
gastiitis. The extension of the mucosal
epithelial cells into the submucosa and
the presence of irregular stiatified ar
rangements of epithelial cells within the
submucosa nrc distinctly dysplastic pat
terns. The experimental concentration
of biphenyls (300 ppm) within the diet
which was sufficient to produce these
conditions in subhuman primates in 3
months is about ten limes the levels
that have occurred in samples of milk
(28 ppm) and of fish (35 ppm) re
ported by the U.S. Food and Drug
Administiation (2). This concentration
is much less than the levels that have
occurred in food products due to in
dustrial accidents (2000 to 3000 ppm)
(5).
The magnitude of the chronic ef
fects which could he produced by I'CH-
induccd hyperliophic gaslrilis is as yet
undetermined. The nausea and vomiting
following human consumption of l'CH's
me possibly a result of the gastric irrita
tions. Weight loss by the experimental
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Fip. 2. Ghnclular epilhclin) cells llial have extended from the mucosa into the sub-
inueosa encompass larfc cysts (C). In some areas (~>) (lie epithelial cells ate
stratified and penetrate into the connective tissue of the submucosa. The cell nuclei
of the stratified area is similar in size and appearance to that of the simple columnar
epithelium that lines the remainder of the cyst (see inset). Serial sections of the tissue
confirmed the stratified arrangement of the epithelial cells (x250, inset x6-K>; scale
rcptcscnls 50 urn),
monkeys and human patients exposed <o the 1'CIVs may be related to gastri tis. Replacement of the parietal cells by the mucus-sccrcting cells which occtiricd in the fundic glands of the more severely affected animals may icsult in achlorhydria and eventual pernicious anemia owing to the lack of intrinsic factor necessary for vitamin B,:, absorption. Invasion of the mtisculatis mucosae and submucosa by the epithelial elements may lead to loss of integrity of the gastric wall with even tual erosion, ulceration, and hemor rhage, as was the ease in monkeys fed chlorinated biphenyl dioxins {12).
Because interest in these environ mental contaminants is only recent, in vestigative efforts have not yet deter mined the long-term carcinogenic poten tial of POli's and PCT's. The associa lion of chionic irritation with cancer, particularly of the stomach, ccmx, oral mucosa, and bronchial epithelium, is well documented. These dysplastic cel lular abnormalities of the hypertrophic gastric mucosa arc likely due to chronic irritation but arc at present short of neoplastic transformation. `1 he develop ment of hypertrophy, hyperplasia, and
dysplasia of the gastric mucosa of sub
human primates necessitates clarifica
tion of the carcinogenic potentials of
these compounds.
' J. U. Au.i:n
D. 11. Noiuuck
Department of Pathology, Medical
School, and Regional Primate Reseatch,
Center, University of Wisconsin,
Madison 53705
.
Itcfcrrnret t>nd Notrs
1. K. Y\ Jliv.bronpli, P, Kicche, D. H. Tc.-iVa!!,
5. O. Herman, M. N. Kinen, Nature 220, 1098 (19CsS).
2. A. C. Kolbyc, Environ, ilrohh Ftni'cct, 1,
$$ (191?),
3. G. 1\ Puri, MM., p, 55.
A, A. R. Yobs, MM., p. 19.'
5. M. Kur.nfutnc, T. Yosltfmma, 3. MalMUiAa,
A. Yam.^ri'nii. MM., p. 119.
6. 3. O. Vos, i/'lci., p. J05.
7. 1>. H. Norback and 3. K. Allrn, Fed. J'roc. 29, E!f (1970).
8. If. NNhifumJ, Arch. Environ. Jfcalth 21, (20
o;vo).
9. ), L. LJneer and D. P. Pcnil. Nature 228,
781 (1970).
10. M. Ot:*vvn, Fukuokti-Isaku-'/ctsfil, 02, 74
(1971).
11. 3. hiltnnn p'xJ II. C, Cecil, 3. A^iic. Fond
them. JR. J108 (1970).
12. 1. K. Alien ami L. A. Cars'.cn*. Aruer. J.
Vet. Kn. 28. 15H (3967).
13. This voi): v-.tc suppoiud (>' N1H pa-m
1 -5>rKV4?2 j-nd RR001G7, and Wisconsin Sea
Grant Piopram.
20 October J972
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