Occupational arsenic exposure and genitourinary cancer: systematic review and meta-analysis

BACKGROUND

Existing evidence suggests that ingestion of high doses of arsenic through drinking water is associated with an increased risk of genitourinary cancers, while systematic evidence on workers exposed to arsenic is lacking.

AIMS

The aim of this study is to systematically review the evidence on the association between occupational exposure to arsenic and genitourinary cancer risk and mortality.

METHODS

A systematic literature search was carried out on Pubmed, Web of Science and Embase by including cohort and case-control studies. Study-specific relative risks (RRs) and the corresponding 95% confidence intervals (CIs) were pooled using Mandel-Paule random-effects model. Contour-enhanced funnel plot and Egger's test were used to assess the occurrence of publication bias.

RESULTS

A total of 17 studies were included in the meta-analysis, 7 on cancer incidence (n = 161,244 individuals) and 10 on cancer mortality (n = 91,868). Most of them were cohort (71%) and industry-based studies (59%). The meta-analysis failed to detect an increased risk of genitourinary cancers among workers exposed to arsenic, except for a suggestive but not significant positive association for bladder cancer incidence (RR: 1.26, 95% CI: 0.89, 1.80), although this estimate was based on only three studies. No compelling evidence of publication bias was found (P = 0.885).

CONCLUSIONS

Our findings did not show an association between occupational exposure to arsenic and genitourinary cancers, although further high-quality studies with detailed exposure assessment at the individual level are needed to clarify this relationship.

The Cardiologist's Role in the Management of Patients with a Genitourinary Cancer

Increased life expectancy due to improved cancer prognosis, shared determinants (e.g., tobacco use), and cardiovascular toxicities related to cancer therapies, including the adverse cardiometabolic effects of androgen deprivation therapy for prostate cancer, make cardiovascular disease an frequent and important co-morbidity in patients with a genitourinary malignancy. Complex cardiovascular disease can pose significant challenges in the management of these patients given the uncertainties related to the best approach to reconcile ischemic and bleeding risks, and the role of invasive cardiovascular interventions in individuals with advanced cancer. In this review, we discuss the current evidence that informs decision-making in this clinical context.

Nonpulmonary outcomes of asbestos exposure

The adverse pulmonary effects of asbestos are well accepted in scientific circles. However, the extrapulmonary consequences of asbestos exposure are not as clearly defined. In this review the potential for asbestos to produce diseases of the peritoneum, immune, gastrointestinal (GIT), and reproductive systems are explored as evidenced in published, peer-reviewed literature. Several hundred epidemiological, in vivo, and in vitro publications analyzing the extrapulmonary effects of asbestos were used as sources to arrive at the conclusions and to establish areas needing further study. In order to be considered, each study had to monitor extrapulmonary outcomes following exposure to asbestos. The literature supports a strong association between asbestos exposure and peritoneal neoplasms. Correlations between asbestos exposure and immune-related disease are less conclusive; nevertheless, it was concluded from the combined autoimmune studies that there is a possibility for a higher-than-expected risk of systemic autoimmune disease among asbestos-exposed populations. In general, the GIT effects of asbestos exposure appear to be minimal, with the most likely outcome being development of stomach cancer. However, IARC recently concluded the evidence to support asbestos-induced stomach cancer to be "limited." The strongest evidence for reproductive disease due to asbestos is in regard to ovarian cancer. Unfortunately, effects on fertility and the developing fetus are under-studied. The possibility of other asbestos-induced health effects does exist. These include brain-related tumors, blood disorders due to the mutagenic and hemolytic properties of asbestos, and peritoneal fibrosis. It is clear from the literature that the adverse properties of asbestos are not confined to the pulmonary system.

Genitourinary long-term outcomes for childhood cancer survivors

The treatment of pediatric malignancies represents one of the success stories of modern medicine. As survival has increased, the focus is now on minimizing harmful effects of treatment. There continue to be late toxicities and secondary malignancies of the genitourinary (GU) system for childhood cancer survivors related to the specific therapeutic exposures. A systematic approach is important for prevention and treatment of these adverse late GU effects.

Workgroup report: National Toxicology Program workshop on Hormonally Induced Reproductive Tumors - Relevance of Rodent Bioassays

The National Toxicology Program (NTP) is currently reviewing its research portfolio as part of its efforts to implement the NTP Roadmap to achieve the NTP Vision for the 21st century. This review includes a recent workshop, "Hormonally Induced Reproductive Tumors-Relevance of Rodent Bioassays," held 22-24 May 2006, that was organized to determine the adequacy and relevance to human disease outcome of rodent models currently used in the 2-year bioassay for four types of hormonally induced reproductive tumors (ovary, mammary gland, prostate, and testis). In brief, none of the workshop's breakout groups felt the currently used models are sufficient. For some types of tumors such as prostate, no adequate animal models exist, and for others such as ovary, the predominant tumors in humans are of different cellular origins than those induced by chemicals in rodents. This inadequacy of current models also applies to the testis, although our more complete understanding of the responses of Leydig cells to hormonal changes in rats may prove predictive for effects in humans other than cancer. All breakout groups recommended that the NTP consider modifying its testing protocols (i.e., age at exposure, additional end points, etc.) and/or using alternative models (i.e., genetically engineered models, in vitro systems, etc.) to improve sensitivity. In this article we briefly review the workshop's outcome and outline some next steps forward in pursuing the workshop's recommendations. Breakout group reports and additional information on the workshop, including participants, presentations, public comments and background materials, are posted on the NTP website.

Clinical implications of DES

Once prescribed to pregnant women to prevent risk of spontaneous abortion, diethylstilbestrol (DES) is now associated with an increased risk of breast cancer, clear cell adenocarcinoma (CCA) of the vagina and cervix, and reproductive anomalies. This article will summarize the potential long-term health implications of DES, the role of nurse practitioners in identifying exposed individuals, and proper clinical management.

Chemoprevention of lung carcinogenesis by cacao liquor proanthocyanidins in a male rat multi-organ carcinogenesis model

The effects of cacao liquor proanthocyanidins (CLPr) on tumorigenesis were investigated using a multi-organ carcinogenesis model in male F344 rats receiving combined treatment with a single i.p. injection of diethylnitrosamine (100 mg/kg body wt), four i.p. injections of N-methylnitrosourea (20 mg/kg body wt), four s.c. injections of dimethylhydrazine (40 mg/kg body wt), along with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine and then 0.1% 2,2'-dihydroxy-di-n-propylnitrosamine, both in the drinking water, for 2 weeks each, during the initial 4-week period (DMBDD treatment). Starting 1 week thereafter, rats were administered CLPr at a dose of 0.025% or 0.25% and the experiment was terminated at week 36. The final survival rate for the DMBDD+0.25% CLPr group was significantly greater than for the DMBDD alone group. In the lung, significant reduction in the incidence and multiplicity of carcinomas was also observed, and in the thyroid, quantitative values for adenomas also tended to decrease in a CLPr dose-dependent manner. No significant modification in the small intestine, colon or kidney was evident. These results indicate that CLPr exerts chemopreventive effects in the lung without any promoting influence in other major organs.

The Koebner phenomenon in immunosuppression-related Kaposi's sarcoma

The Koebner phenomenon has been reported to develop in classic or acquired immune deficiency syndrome-related Kaposi's sarcoma (KS). A 12-year-old kidney transplant recipient who developed immunosuppression-related KS showed reoccurrence of lesions in some previously intact incision sites following removal of tumor, suggesting Koebner phenomenon. It is recommended that surgeons be careful when planning surgical interventions in patients with certain skin disorders in which Koebner phenomenon is known to develop.

Multiorgan transplacental and neonatal carcinogenicity of 3'-azido-3'-deoxythymidine in mice

The anti-HIV drug 3'-azido-3'-deoxythymidine (AZT) is used successfully for reduction of perinatal viral transmission. However toxic side effects including carcinogenesis are possible. To test this, pregnant CD-1 Swiss mice were given 25.0 or 12.5 mg AZT on gestation days 12-18. Previously we reported an increase in lung, liver, and female reproductive system tumors in offspring euthanized at 1 year (Olivero et al., J. Natl. Cancer Inst. 89, 1602-1608, 1997). Findings for all remaining offspring up to 2 years old are reported here. AZT effects were most prominent in female offspring, with a significant threefold increase in lung tumors, a reduction in lymphoblastic and follicle center cell lymphomas, and a significant increase in histiocytic sarcomas (0 in controls, 3% after low-dose AZT, and 8% after high-dose AZT, p = 0.022). Dose-dependent incidences of mammary gland, ovarian, and seminal vesicle tumors were low but significant: 0/106 controls, 3/105 low-dose, and 8/105 high-dose mice presented one of these neoplasms (p = 0.0025). Incidences of females showing any clearly AZT-related neoplasm, in lung, liver, ovary, or mammary gland or histiocytic sarcoma, in the second year, were 12/32 after the low dose and 14/27 after the high dose vs 3/23 controls (p = 0.0045). Also, the sensitivity of neonatal mice was assessed by administration of 25, 50, 100, or 200 mg/kg AZT on postnatal days 1 through 8. The effects at 2 years were similar to those seen after transplacental exposure, with significant increases in lung, liver, and mammary tumors in females. The results confirm that AZT is a moderately effective perinatal carcinogen in mice, targeting several tissue types.

Ultrasonic diagnosis of 3,2'-dimethyl-4-aminobiphenyl induced tumors in the urogenital organs of F344 rats

The usefulness of transabdominal ultrasonography in the diagnosis of 3,2'-dimethyl-4-aminobiphenyl- and testosterone propionate-induced tumors of the urogenital organs was evaluated in F344 rats. Seven mass lesions (1 ventral prostate, 1 dorsolateral prostate, 3 seminal vesicles, and 1 kidney) in the urogenital organs could easily be diagnosed concerning size and localization by ultrasound. Histological examination revealed a lesion in the ventral prostate to be an abscess and the other tumors to be malignant. Three hydronephroses by tumor invasion to the ureter, and six tumors in organs other than the urogenital organs could be detected by ultrasound. The threshold of malignant tumor detection by ultrasound was 7 mm in actual length. The size of the mass lesion estimated by ultrasound correlated well with the direct measurement (r = 0.96). Transabdominal ultrasonography is useful for diagnosing the localization of experimental tumors and accurately measuring their size in the urogenital organs of rats.

Pathology of chronic polychlorinated biphenyl (PCB) feeding in rats

The hepatocarcinogenic effect of Clophen A 30 and Clophen A 60 was tested in male weanling rats by long-term feeding over a period of 832 days. The mortality rate was investigated in 100-day intervals. In the first 800 days liver carcinoma accounted for 21% of necropsies in the Clophen A 60 group but only 2% of the necropsies in the Clophen A 30 group and none in the control animals. The tumors were first observed after 700 days. After 800 days hepatocellular carcinoma was the most common lesion observed in the Clophen A 60 animals (61%) whereas it was only observed in 3% of animals in the Clophen A 30 group and 2% in the controls. Preneoplastic lesions, such as foci of hepatocellular alterations and neoplastic nodules, were first observed after Day 500. The incidence of foci predominated in all time intervals, but an increase in neoplastic nodules and hepatocellular carcinomas was observed with increased time. There was a marked trend from foci to neoplastic nodule to hepatocellular carcinoma with time. The total mortality rate and the incidence of thymoma, inflammatory lesions of the urogenital tract, in the experiment were significantly reduced by Clophen administration. Whether this protective effect could be induced by polychlorinated biphenyls (PCBs) is discussed.

Cancer risk among oil refinery workers. A review of epidemiologic studies

The possibility that excess cancers result from occupational exposures in oil refineries has generated a great deal of interest. Ecological studies and case-control studies in the general population have suggested a positive association between oil industry activity and cancer rates, with more direct evidence provided by studies of refinery employees. The eight investigations of cancer risks among refinery employees are critically reviewed. The methodological strengths and weaknesses of these studies are evaluated with an emphasis on the likely impact on the results. While the results are markedly inconsistent across studies, there is some suggestion of excess risks for melanoma and for brain, stomach, kidney, and pancreatic cancers. Problems with exposure characterization, latency, and potential confounding factors limit all of the studies that were reviewed.

Ineffectiveness of topical idoxuridine in dimethyl sulfoxide for therapy for genital herpes

The efficacy and toxicity of topical applications of 30% idoxuridine in dimethyl sulfoxide, dimethyl sulfoxide alone, or saline in 96 recurrent and 39 first episodes of genital herpes simplex virus (HSV) infection were compared. Drug was applied to lesions four times daily for seven days. In recurrent episodes, the duration of viral shedding after beginning idoxuridine in dimethyl sulfoxide use was significantly shorter (0.6 days) than with dimethyl sulfoxide (1.4 days) or saline (2.0 days) (P less than .05). In primary episodes, viral shedding lasted 2.6 days with idoxuridine in dimethyl sulfoxide and 8.4 days with dimethyl sulfoxide or saline. Idoxuridine in dimethyl sulfoxide had no effect in recurrent or primary HSV on duration of symptoms, new lesion formation, healing time, or risk of subsequent recurrence. Complications in patients given idoxuridine in dimethyl sulfoxide included local burning, generalized contact dermatitis, and vulvar carcinoma in situ. Thirty percent idoxuridine in dimethyl sulfoxide has no effect on clinical manifestations of genital HSV infection and may be hazardous.

The role of toxicity in the carcinogenicity of endosulfan

Two studies have been undertaken on the toxicity and carcinogenicity of endosulfan, a chlorinated cyclodiene - the NCI Endosulfan Rat Study and the NCI Endosulfan Mouse Study. Histological sections have been examined and the results of this review are based on my diagnoses. Endosulfan is highly toxic for male and female osborne-Mendel rats, particularly for male rats. The chemical causes interstitial fibrosis or acute tubular necrosis of the kidney and death. These lesions, as well as atrophy of the testes, polyarteritis, parathyroid hyperplasia, osteitis fibrosis of bone, and abscesses of the lung, interfere with the health of the animals and with the development of neoplasms. Endosulfan, even though it is extremely toxic, is carcinogenic for male and female Osborne-Mendel rats. The chemical induced malignant neoplasms at all sites in male and female rats and the endocrine organs in male rats. Rats of both sexes developed lymphosarcomas, and female rats had neoplasms of the reproductive system. Endosulfan is also carcinogenic for the liver of female mice.

The effect of N-nitroso-2-methoxy-2,6-dimethylmorpholine on endocrine and exocrine pancreas of Syrian hamsters

N-Nitroso-2-methoxy-2,6-dimethylmorpholine (MeNDMM), a cyclic derivative of the proposed proximate pancreatic carcinogen N-nitroso(2-hydroxypropyl) (2-oxopropyl)amine (HPOP), is shown to have an almost selective cytotoxic effect on pancreatic beta-cells when a single high dose is given to Syrian hamsters. Hence in this aspect its effect is comparable to that of streptozotocin, which has a glucose moiety similar to the MeNDMM structure. However, contrary to the effect of streptozotocin, low single (subdiabetogenic) doses of MeNDMM led to the development of pancreatic ductular and mixed ductular-insular neoplasms; only 1 animal also had islet cell adenoma. It therefore seems that MeNDMM possesses an affinity for both endocrine and exocrine pancreatic tissue. Other target tissues of MeNDMM were the forestomach, intra- and extrahepatic bile ducts, liver, kidneys and vagina. The tumors of these organs appeared in various incidences, partially in relation to dose and/or survival time. The possible mechanisms of the MeNDMM effect upon the endocrine and the exocrine pancreas is discussed.

Experimental identification of genitourinary carcinogens

Classic principles of pharmacology and toxicology are not entirely applicable to carcinogenesis. The existence of thresholds for carcinogens has yet to be proved. The use of high dosages in laboratory animals is an acceptable and necessary practice in identifying carcinogens. Generally, carcinogenicity is a result of the intrinsic property of a chemical and is independent of dosage and duration of exposure; however, the detection of carcinogenicity is dose-related. Not all chemicals are carcinogens. A properly designed and conducted study in laboratory animals is a scientifically valid way of identifying carcinogens that may pose a risk to humans. The route by which a chemical is administered to laboratory animals need not be identical to the way in which humans are exposed. The target organs in laboratory animals may or may not be the same as in humans. The inherent limitations of epidemiologic studies severely restrict their usefulness for detecting cancer-causing agents in human beings. Therefore, carcinogens identified in laboratory animals should be treated as if they cause cancer in human beings as well.

The effect of nerve growth factor and antibodies to nerve growth factor on ethylnitrosourea carcinogenesis in mice

The specific induction of neural tumors by the carcinogen, ethylnitrosourea (ENU), can be enhanced by reducing the in vivo nerve growth factor (NGF) levels in mice using IgG directed against the biologically active subunit of NGF (anti-NGF). This effect is reversible, confirming that the altered endogenous NGF levels do return to normal following injection with anti-NGF. Correspondingly, no neural tumors were observed when in vivo NGF levels were elevated by administering exogenous NGF with ENU. The higher physiological levels of NGF in control mice when compared to control rats might explain why fetal administration of ENU to rats results in a greater percentage of neural tumors. This would suggest that the long studied maturation effect that NGF has on developing neural cels of the peripheral nervous system may also influence neural oncogenesis.

Carcinogenic effect of N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine, a postulated proximate pancreatic carcinogen in Syrian hamsters

N-Nitroso(2-hydroxypropyl)(2-oxopropyl)amine (HPOP) proved to be a potent carcinogen in Syrian golden hamsters. The compound is an in vivo metabolite of N-nitrosobis(2-hydroxypropyl)amine, N-nitrosobis(2-oxopropyl)amine (BOP), and N-nitroso-2,6-dimethylmorpholine and a postulated proximate pancreatic carcinogen in hamsters. As with BOP, HPOP induced a higher incidence of pancreatic ductular adenocarcinomas than did N-nitrosobis(2-hydroxypropyl)amine and N-nitroso-2,6-dimethylmorpholine, and these neoplasms showed a great tendency for invasion and metastasis. Also, HPOP induced tumors of the forestomach, liver, gallbladder, kidneys, and vagina (as did BOP). However, HPOP [unlike BOP, but like N-nitrosobis(2-hydroxypropyl)amine and N-nitroso-2,6-dimethylmorpholine] led to tumor development in the nasal cavity, larynx, trachea, intestine, Harderian gland, lips, and flank organ. The possible mechanisms of HPOP carcinogenicity are discussed.

Carcinogenicity of toxaphene: a review

Toxaphene is highly carcinogenic in rats and mice. Toxaphene induced malignant neoplasms of the liver in rats. Neoplasms at all sites, as well as malignant neoplasms, were increased in male and female rats ingesting toxaphene. Sarcomas were found more often in male rats and carcinomas in female rats. Neoplasms of the endocrine organs were also increased in male and female toxaphene-treated rats. The incidence of neoplasms of the reproductive system was increased in female rats, as was the incidence of mammary gland neoplasms in male rats. Toxic changes in male rats given toxaphene included interstitial fibrosis of the kidney and atrophy of the testes. Toxaphene induced malignant neoplasms of the liver in male and female mice. The incidence of malignant neoplasms at all sites was also increased. In addition to hepatic neoplasms, male mice had leukemia or lymphosarcoma and females had sarcomas of the uterus.

Carcinogenicity of N-nitrosobis(2-hydroxypropyl)amine and N-nitrosobis(2-oxopropyl)amine in MRC rats

Weekly sc injections of equitoxic doses of N-nitrosobis(2-hydroxypropyl)amine (BHP) and N-nitrosobis(2-oxopropyl)amine (BOP) to Wister-derived MRC rats induced tumors. The incidence, latency, multiplicity, morphologic type, and distribution of these tumors varied according to the compound given. The esophagus was the main target organ for BHP (100%), followed by the respiratory tract (87%), pharynx (80%), colon and liver (each 73%), kidneys (20%), thyroid gland (20%), and urinary bladder and urethra (each 7%). BOP was ineffective in the esophagus and pharynx but induced a higher incidence of tumors in the kidneys (27%), thyroid gland (60%), urinary bladder (33%), and urethra (73%) and fewer neoplasms in the respiratory tract (20%), colon (67%), and liver (53%). In addition, BOP caused a few, apparently primary, prostate squamous cell carcinomas. The results are compared with results of BHP treatment in Sprague-Dawley rats and with results of BHP and BOP treatment in Syrian golden hamsters.

In vivo studies in Syrian golden hamsters: a transplacental bioassay of ten nitrosamines

The carcinogenic effects of low doses of 10 nitrosamines were determined in pregnant Syrian golden hamsters and their offspring. Compounds studied included dimethylnitrosamine, di-n-propylnitrosamine, di-n-butylnitrosamine, nitrosopiperidine, nitrosohexamethyleneimine, 2-dydroxypropyl-propyl-nitrosamine, 2-oxopropyl-propyl-nitrosamine, methylpropylnitrosamine, di(2-hydroxypropyl) nitrosamine, and 4-hydroxybutyl-butyl-nitrosamine. Tumor incidences of all organ systems were almost always higher and latencies shorter in the mothers than in the offspring. Exceptions occurred in the respiratory system in which several compounds induced a low incidence of tumors in the offspring but none in the mothers. Fetal susceptibility appeared greatest toward the end of gestation. For purposes of bioassay, transplacental exposure was less efficient than conventional adult treatment.

Carcinogenicity of saccharin

Saccharin is carcinogenic for the urinary bladder in rats and mice, and most likely is carcinogenic in human beings. The neoplasms of the urinary bladder are malignant and invade and metastasize. Male rats are more susceptible to urinary bladder carcinogenesis than female rats. Rats exposed as fetuses develop neoplasms more readily than rats exposed as weanlings. The lesions in the urinary bladder go through the stages of hyperplasia, hyperplastic nodules, and later carcinomas. The male of the human species ingesting saccharin, as for rats, is more susceptible to carcinogenesis of the urinary bladder than the female. Neoplasms of the urinary bladder in rats were not caused by stones, parasites, sodium, or impurities. There is a cocarcinogenic effect between saccharin and methylnitrosurea for the urinary bladder. Even through carcinomas of the urinary bladder are present in rats given the higher doses of saccharin, one was observed in a female rat given 0.5%. Chronic renal disease develops in rats ingesting saccharin. The disease is more advanced at the lower doses than at the higher doses, suggesting that saccharin at the lower doses does not reach the urinary bladder. Early neoplasms are seen in the renal pelvis of rats given the higher doses of saccharin. The risk ratios for urinary bladder carcinomas in human beings increase with both frequency andduration of saccharin usage. Benign and malignant neoplasms at all sites are significantly increased in mice and rats ingesting the higher doses of saccharin. These neoplasms are present in the reproductive and hematopoietic systems, and to a lesser extent in the lungs, vascular system and squamous epithelium. Neoplasms in some organs develop with the lower doses of saccharin. Lymphosarcomas of the lung are significantly increased in rats given 0.01% saccharin. Chronic renal disease in rats given saccharin interferes with the health and life span and consequently with development of neoplasms. Saccharin initiates neoplasms of the skin when its application is followed by croton oil. Epidemiological studies have not been done for neoplasms other than the urinary bladder in human beings.

[Tumors of the efferent parts of the urinary tract and abuse of analgesics]

Since 1965, when Swedish authors first suggested that analgesic abuse could cause uroepithelial tumors associated with or without analgesic nephropathy, an increasing number of cases have been reported from many parts of the world. In a retrospective analysis of all patients admitted to the medical department of the University Hospital in Basel from 1966 to 1976, records of 20 patients with analgesic nephropathy and tumors of the urinary tract (excluding hypernephroma) were found (17 uroepithelial tumors, 2 sarcomas, 1 chorionepithelioma). Typical symptoms, outcome and actuarial survival of the patients with uroepithelial tumors are summarized. Phenacetin as the common ingredient in analgesic mixtures has been regarded as carcinogenic, since some of its metabolites are similar in chemical structure to well-known industrial carcinogens. In animal experiments malignant tumors have in fact been induced with 2-hydroxylated metabolites and areneoxydes of phenacetin and paracetamol, and there is even more convincing evidence of the carcinogenic properties of N-oxydized metabolites such as N-hydroxy-phenetidine and N-hydroxy-phenacetin. Dimethylnitrosamine formed from aminophenazone appears to be improbable as a cause of uroepithelial tumors associated with analgesic abuse, since aminophenazone has not been a common ingredient of analgesic mixtures in Australia, where the incidence of uroepithelial tumors appears to be as high as in Sweden, where abuse of aminophenazone-containing analgesics has been massive.

Transplacental effects of nitrosamines in Syrian hamsters. II. Nitrosopiperidine

Nitrosopiperidine (NP) was found in Syrian hamsters quantitatively in the maternal blood for more than 8 h after subcutaneous injection, whereas it disappeared from placenta, fetus and amniotic fluid within the same time period. For N6MI, only traces were seen after 2 h in the same tissues. The long-term transplacental effect of a single dose of NP was weak, as demonstrated by a low respiratory tract tumor incidence (P-generation: 54%, F1- generation: 4%). Some tumors occurring in the digestive tract of exposed young were not found in their mothers and not commonly observed in controls. These tumors were considered a borderline transplacental effect. Tumors of other sites (i.e., the urogenital and genital tracts, reticuloendothelial system, endocrine organs and other tissues) corresponded in incidences to the overall fluctuations observed in this hamster colony.

Transplacental effects of nitrosamines in Syrian hamsters. III. Dimethyl- and dipropylnitrosamine

The aliphatic nitrosamines dimethylnitrosamine (DMN), diethylnitrosamine (DEN), dipropylnitrosamine (DPN), and dibutylnitrosamine (DBN) reached fetal tissue in quantitatively measurable amounts after subcutaneous administration to pregnant Syrian hamsters. The compounds were present for at least 2 h in maternal blood, placenta, fetus, and amniotic fluid; DBN was still measurable after 6 h. Only a weak or borderline transplacental effect was seen when incidences and latencies of neoplasms in the respiratory and digestive tracts of the F1-generation were compared with those of the P-generation after exposure to a single dose of DMN or DPN. However, some tumor types occurred at relatively high rates in the young, but were seen only occcasionally in their mothers or in this hamster colony in general.

Effects of repeated applications of two semi-permanent hair dyes to the skin of A and DBAf mice

Two proprietary semi-permanent hair dyes were tested for carcinogenicity in A and DBAf mice by repeated topical applications in aqueous acetone. Mice of both strains developed lymphoid tumours but experimental differences were marked only in DBAf mice. A number of tumours of the ovary and uterus, and some skin papillomas near the penis, occured in dye-treated but not in control DBAf mice. As many hair-dye constituents are known mutagens, adequate carcinogenicity testing of these substances, and epidemiological study of exposed human populations, are needed for evaluating possible health hazard from hair dyeing.

Mortality among employees of PVC fabricators

A cross-sectional mortality study of 4,341 deaths occurring among current and former employees of 17 PVC fabricators during 1964-1973 is presented. The objectives are: (1) to identify any angiosarcoma deaths among the employees of these fabricators, and (2) to examine the distribution of deaths by cause. No angiosarcoma deaths were found among the study group. Sex-race-cause-specific Proportionate mortality Ratios (PMR's) were computed, using the corresponding U.S. mortality as the standard. Among white employees, there appears to be an excess in total cancer mortality, particularly that of the digestive system. Observed deaths were found to exceed the expected in cancers of the breast and urinary organs among white females. Deficit mortality was observed in cirrhosis of liver among both male and female white employees.

A potent pancreatic carcinogen in Syrian hamsters: N-nitrosobis(2-oxopropyl)amine

N-Nitrosobis(2-oxopropyl)amine (BOP), a further postulated beta-metabolite of di-n-propylnitrosamine, induced a high incidence of pancreatic duct adenomas and adenocarcinomas as early as 13 weeks in Syrian hamsters receiving weekly sc injections for life and a few pancreatic adenomas, after 28 weeks, in those given a single sc dose. Compared to related compounds, N-nitrosobis(2-hydroxypropyl)amine and N-nitrosobis(2-acetoxy-propyl)amine which are also pancreatic carcinogens, BOP induced only a few neoplasms of the lung, liver, and kidney and none in the nasal cavity, larynx, and trachea. The results therefore indicate progress in developing a more specific model for pancreatic carcinogenesis studies.

A carcinogenicity assay of Mirex in Charles River CD rats

The long-term administration of 50 and 100 ppm of Mirex in the diets of male and female Charles River CD rats was associated with a spectrum of liver lesions, from foci or areas of cellular alteration and neoplastic nodules to hepatocellular carcinoma. Statistically significant numbers of neoplastic nodules were observed in the livers of male rats receiving the high dose. Neoplastic nodules and hepatocellular carcinomas were not observed in control rats.

Drinking water and cancer mortality in Louisiana

Multivariant regression analysis indicates a statistically significant relation between cancer mortality rates in Louisiana and drinking water obtained from the Missippi River. This is true for total cancer, cancer of the urinary organs, and cancer of the gastrointestinal tract.

Tobacco and tobacco smoke

Epidemiologic studies have demonstrated a causal relation between smoking of cigarettes and cancer of the lung in man. Women smokers, cigar, and pipe smokers also face an increased risk for lung cancer. Prospective and retrospective studies have found a correlation between smoking of cigarettes, cigars, and pipes and cancer of the oral cavity, larynx, and esophagus and for cigarette smokers increased risks to develop cancer of the pancreas, kidney, and urinary bladder. Dose responses have been established between number of cigarettes smoked and cancer of the respiratory and upper digestive tract. Tobacco chewers face an increased risk for cancer of the mouth and esophagus. Tobacco smoke has induced tumors of the lung in the dogs and of the larynx of hamsters. The particulate matter of the smoke is carcinogenic to the skin of mice and rabbits, and the bronchi and connective tissue of rats. In tobacco smoke were identified tumor initiators, tumor promoters, cocarcinogens and organ specific carcinogens. Chewing tobacco is a tumor promoting agent and contains traces of tobacco specific and carcinogenic nitrosamines. Ten to 15 yr after giving up smoking the ex-smoker faces the same low risk to develop cancer of the upper digestive tract, the lung, the pancreas, and the urinary tract as the nonsmoker. It should be our goal, therefore, to prevent young people from starting the smoking habit and to convince the smoker to quit smoking. So far, we can report no success in terms of decreasing smoking habits among younger people. On the other hand, we can take satisfaction from the fact that antismoking propaganda has had an effect on college educated males, that among the population as a whole, there is a considerable number of exsmokers; that smoking cessation clinics do prove cost effective and if they were to become part of every health care center, they could help a large number of heavy smokers who cannot seem to stop smoking on their own. We can also report that there has been a significant reduction in the tar yield of American cigarettes, a reduction which we hope will continue; that the tumorigenic activity of tobacco as measured in animal studies, has decreased; and that as a consequence of the above, the risk of lung cancer and other tobacco-related cancers among smokers of these cigarettes is lower than in years past. It is unlikely that man will ever be able to inhale smoke components as harmless as unpolluted air, but as long as we have a society which accepts this habit and as long as people find satisfaction in smoking, we must work towards the day when tobacco-related cancers and other diseases will be reduced to a minimum. With the world wide coperation of the scientific community, the Departments of Agriculture, and the tobacco industry, it is our hope that this goal will be achieved.

[Urinary tract carcinomas in gas industry employees (author's transl)]

Arising from a retrospective investigation of the causes of death in active and pensioned employees from the author's sphere of observation, the increased occurence of urinary tract carcinoma in furnace battery and pipe system workers in the gas industry is pointed out. Statistical studies suggest a causal connection between exposure to tar in these jobs and the urinary tract carcinomas. The necessity for industrial medical precautions is commented on.

Effects of nerve growth factor administration of N-ethyl-N-nitrosourea carcinogenesis

We attempted to determine whether the sympathetic nervous system in rodents is susceptible to co-carcinogenesis, employing murine salivary nerve growth factor (NGF) as a co-carcinogenic agent. NGF had no co-carcinogenic effect with either methylcholanthrene or ethylnitrosourea (ENU) on the sympathetic nervous system of the mouse, whether administered transplacentally, postnatally, or both transplacentally and postnatally. At a dose of ENU of 30 mug/g body weight, NGF did not shorten the latent period for tumor induction of BD-IX rats. In contrast, a 25% reduction in latent period was brough about by NGF for tumor appearance in BD-IX rats receiving 90 mug/g ENU. In both cases the frequency of urogenital tumors in rats was increased as a result of NGF administration, at the apparent expense of neural tumors.