dieldrin and Liver-Neoplasms

The rodent liver is a target organ for the action of several non-genotoxic carcinogens. These include dioxins, polychlorinated biphenyls, phenobarbital, peroxisome proliferators and organochlorine pesticides. These chemicals disrupt the homeostasis of the liver by perturbing hepatocyte cell death and proliferation, causing hyperplasia leading to tumour formation. Significant progress has been made towards elucidating the mechanisms of action of these toxicants since the discovery of receptors that bind specific classes of xenobiotics. Dioxins and polychlorinated biphenyls bind to the aryl hydrocarbon receptor, phenobarbital binds to the constitutive androstane receptor and peroxisome proliferators act via the their activated receptor alpha. These three receptors have ligand-dependent transcription activities and therefore mediate changes in gene expression in response to toxicant exposure. The development of transgenic mouse strains where the genes for these receptors are disrupted has demonstrated that receptor activity is essential for the toxicity of these carcinogens. This implies that changes in the expression of key target genes control proliferation and apoptosis in the xenobiotic-induced hepatocyte phenotype.

Topics: Animals; Apoptosis; Carcinogens; Cell Division; Dieldrin; Dioxins; Hepatocytes; Liver; Liver Neoplasms; Peroxisome Proliferators; Phenobarbital; Polychlorinated Biphenyls; Pyridines; Receptors, Cytoplasmic and Nuclear; Rodentia

Topics: Animals; Dieldrin; Humans; Liver Neoplasms; Liver Neoplasms, Experimental; Occupational Diseases; Occupational Exposure; Phenobarbital; Risk Assessment; Species Specificity

Topics: Animals; Carcinogens; Dieldrin; Free Radicals; Gene Expression Regulation, Neoplastic; Liver Neoplasms; Mice; Oncogenes; Oxidative Stress; Rats; Transcription Factor AP-1

Topics: Animals; Butylated Hydroxytoluene; Carcinogens; Cell Line; DDT; Dieldrin; Dioxins; Drug Evaluation, Preclinical; Humans; Liver Neoplasms; Liver Neoplasms, Experimental; Mutagenicity Tests; Mutagens; Neoplasms; Phenobarbital; Structure-Activity Relationship

Topics: Aldrin; Animals; Carcinogens; DDT; Dieldrin; Dose-Response Relationship, Drug; Drug Synergism; Enzyme Induction; Food Contamination; Government Agencies; Liver Neoplasms; Lung Neoplasms; Neoplasms; Pesticide Residues; Pesticides; Photolysis; United States; United States Food and Drug Administration

Dieldrin has been shown to induce liver tumors selectively in mice. Although the exact mechanism is not fully understood, previous studies from our laboratory and others have shown that dieldrin induced liver tumors in mice through a non-genotoxic mechanism acting on tumor promotion stage. Two studies were performed to examine the role of nuclear receptor activation as a possible mode of action (MOA) for dieldrin-induced mouse liver tumors. In the initial study, male C57BL/6 mice (6- to 8-week old) were treated with dieldrin in diet (10 ppm) for 7, 14, and 28 days. Phenobarbital (PB), beta-naphthoflavone (BNF) and Di (2-ethylhexyl) phthalate (DEHP) were included as positive controls in this study for evaluating the involvement of CAR (constitutive androstane receptor), AhR (aryl hydrocarbon receptor) or PPARα (peroxisome proliferator activated receptor alpha) in the MOA of dieldrin hepatocarcinogenesis. A significant increase in hepatocyte DNA synthesis (BrdU incorporation) was seen in treated mice compared with the untreated controls. Analysis of the expression of the nuclear receptor responsive genes revealed that dieldrin induced a significant increase in the expression of genes specific to CAR activation (Cyp2b10, up to 400- to 2700-fold) and PXR activation (Cyp3a11, up to 5- to 11-fold) over untreated controls. The AhR target genes Cyp1a1 and Cyp1a2 were also slightly induced (2.0- to 3.7-fold and 1.7- to 2.8-fold, respectively). PPARα activation was not seen in the liver following dieldrin treatment. In addition, consistent with previous studies in our lab, treatment with dieldrin produced significant elevation in the hepatic oxidative stress. In a subsequent study using CAR, PXR, and CAR/PXR knockout mice, we confirmed that the dieldrin-induced liver effects in mouse were only mediated by the activation of CAR receptor. Based on these findings, we propose that dieldrin induced liver tumors in mice through a nuclear receptor CAR-mediated mode of action. The previously observed oxidative stress/damage may be an associated or modifying factor in the process of dieldrin-induced liver tumor formation subsequent to the CAR activation.

Topics: Animals; Aryl Hydrocarbon Hydroxylases; Cell Transformation, Neoplastic; Constitutive Androstane Receptor; Cytochrome P450 Family 2; Dieldrin; DNA Replication; Enzyme Induction; Insecticides; Liver; Liver Neoplasms; Male; Mice, Inbred C57BL; Mice, Knockout; Oxidative Stress; PPAR alpha; Pregnane X Receptor; Receptors, Cytoplasmic and Nuclear; Signal Transduction; Steroid Hydroxylases

Dieldrin-induced hepatocarcinogenesis, which is seen only in the mouse, apparently occurs through a nongenotoxic mechanism. Previous studies have demonstrated that dieldrin induces hepatic DNA synthesis in mouse, but not rat liver. A number of nongenotoxic hepatocarcinogens have been shown to increase hepatocyte nuclear ploidy following acute and subchronic treatment in rodents, suggesting that an induction of hepatocyte DNA synthesis may occur without a concomitant increase in cell division. The current study examined the effects of dieldrin on changes in hepatocyte DNA synthesis, mitosis, apoptosis, and ploidy in mouse liver (the sensitive strain and target tissue for dieldrin-induced carcinogenicity) and the rat liver (an insensitive species). Male F344 rats and B6C3F1 mice were treated with 0, 1, 3, or 10 mg dieldrin/kg diet and were sampled after 7, 14, 28, or 90 d on diet. Liver from mice fed 10 mg dieldrin/kg diet exhibited significantly increased DNA synthesis and mitosis at 14, 28, or 90 d on diet. In rats, no increase in DNA synthesis or mitotic index was observed. The apoptotic index in liver of mice and rats did not change over the 90-d study period. Exposure of mice to only the highest dose of dieldrin produced a significant increase in octaploid (8N) hepatocytes and a decrease in diploid (2N) hepatocytes, which were restricted primarily to centrilobular hepatocytes, with the periportal region showing little or no change from control. No changes in hepatocyte nuclear ploidy were observed in the rat. This study demonstrates that exposure to high concentrations of dieldrin is accompanied by increased nuclear ploidy and mitosis in mouse, but not rat, liver. It is proposed that the observed increase in nuclear ploidy in the mouse may reflect an adaptive response to dieldrin exposure.

Topics: Animals; Apoptosis; Cell Division; Dieldrin; Disease Models, Animal; DNA; Environmental Exposure; Hepatocytes; Insecticides; Liver Neoplasms; Male; Mice; Mice, Inbred Strains; Mitotic Index; Ploidies; Rats; Rats, Inbred F344

The effect of cessation of phenobarbital and dieldren treatment on hepatic focal lesion growth in male B6C3F1 mice was investigated. Following induction of lesions by diethylnitrosamine, mice were placed on control NIH-07 diet (control diet) or NIH-07 diet containing either dieldrin (10.0 mg/kg diet) or phenobarbital (500 mg/kg diet). Mice were sacrificed after 30 and 60 days of dietary treatment. Two additional groups of mice were fed either the dieldren- or phenobarbital-containing diet for 30 days followed by feeding of NIH-07-only diet for an additional 30 days. The effect of treatment and removal of dieldrin or phenobarbital on lesion growth was examined by measuring both the number of focal lesions per liver and the relative volume of focal lesions. In addition, the rate of cell proliferation and programmed cell death in focal lesion growth was investigated by examining DNA synthesis and apoptosis in the focal lesions. Dietary dieldrin or phenobarbital increased the number of focal lesions and the focal lesion volume. In both dieldrin- and phenobarbital-treated mice, an increased number of eosinophilic lesions were seen. The focal lesion volume was increased in both eosinophilic and basophilic lesions. Dieldrin and phenobarbital treatment also increased the DNA synthetic labeling index in both eosinophilic and basophilic lesions. Removal of dieldrin or phenobarbital from the diet after 30 days of promoter treatment decreased the total number and volume of hepatic focal lesions. The labeling index of the focal lesions was also decreased in these mice. At the terminal sacrifice, the percentage of apoptotic cells in focal lesions was higher in mice fed dieldrin- or phenobarbital-containing diets for the entire 60 days than in mice returned to control diet for the last 30 days. Eosinophilic lesions were more dependent on the presence of a promoting stimulus than the basophilic lesions. These data indicate that induction and maintenance of the growth of some preneoplastic lesions in the mouse may be dependent upon continuous tumor promoter treatment.

Topics: Animals; Apoptosis; Body Weight; Carcinogens; Cell Division; Dieldrin; Diet; Diethylnitrosamine; Eosinophils; Liver; Liver Neoplasms; Male; Mice; Mice, Inbred Strains; Organ Size; Phenobarbital; Precancerous Conditions

Topics: Animals; Carcinogens; Dieldrin; Liver Neoplasms; Male; Mice; Mice, Inbred Strains; Phenobarbital; Precancerous Conditions; Rats; Rats, Inbred F344

The frequency and pattern of mutations at codon 61 of the c-Ha-ras protooncogene were analysed in glucose-6-phosphatase-deficient hepatic lesions of male C3H/He mice occurring either spontaneously or after continuous treatment with 10 p.p.m. dieldrin or 500 p.p.m. phenobarbital (PB) in their diet. At 52 weeks after start of promoter administration, enzyme-altered liver lesions had developed in 41% (15/37) of untreated control mice and in 67% (10/15) and 63% (10/16) of mice treated with dieldrin or PB respectively. The average numbers of focal lesions per mouse were 0.57 in the control, 1.5 in the dieldrin and 1.0 in the PB group. Lesions were punched out from frozen liver sections and used for mutation analysis by allele-specific oligonucleotide hybridization following in vitro amplification of DNA via polymerase chain reaction. In the control group, 12 out of 21 liver lesions (57%) showed c-Ha-ras mutations, while five out of 23 (22%) and four out of 16 (25%) lesions were mutated in the dieldrin and PB groups. Taking the different numbers of animals in the three experimental groups into account, our data indicate that the tumour promoters increased the frequency of c-Ha-ras wild-type but not of c-Ha-ras mutated focal liver lesions, suggesting that the mutations had occurred spontaneously and were not related to treatment. Since c-Ha-ras mutations were found to be frequent in large but infrequent in small hepatocellular lesions, these mutations may represent in livers of C3H/He mice an endogenous promoting principle that provides a selective growth advantage to the mutated progenitor cells.

Topics: Amino Acid Sequence; Animals; Codon; Dieldrin; Genes, ras; Glucose-6-Phosphatase; Liver; Liver Neoplasms; Male; Mice; Mice, Inbred C3H; Molecular Sequence Data; Mutation; Phenobarbital; Polymerase Chain Reaction

Mutations in codon 61 of the Ha-ras proto-oncogene have been shown to occur with a high frequency in both spontaneous and carcinogen-induced liver tumours of the B6C3F1 mouse. In the present study we analysed the frequency and pattern of Ha-ras mutations in liver tumours in a different strain of mice, namely the CF1 mouse. These liver tumours occurred spontaneously or after administration of either aflatoxin B1, phenobarbital or dieldrin. Mutation analysis was performed by in vitro amplification of DNA using the polymerase chain reaction combined with selective oligonucleotide hybridization. Our results demonstrate the presence of mutations in the Ha-ras gene in liver tumours of the CF1 strain. In total, 6 out of 35 liver tumours of male CF1 mice, two of them occurring after treatment with the tumour promoter phenobarbital solely, contained mutations at either the first or second base of codon 61 of the Ha-ras gene. The types of mutations found in liver tumours of the CF1 mouse were very similar to those described in the B6C3F1 mouse, indicating that mutations in the Ha-ras proto-oncogene may represent a critical event in mouse hepatocarcinogenesis.

Topics: Aflatoxin B1; Aflatoxins; Animals; Base Sequence; Carcinogens; Dieldrin; DNA, Neoplasm; Genes, ras; Liver Neoplasms; Mice; Mice, Inbred Strains; Molecular Sequence Data; Mutation; Oligonucleotide Probes; Phenobarbital; Polymerase Chain Reaction

The kinetics of nuclear polyploidization in livers of CF-1 mice exposed to dieldrin were studied at concentrations of 0, 0.1, 1, 5 and 10 p.p.m. in the diet, in 'steady-state' situations (which are reached within a few weeks after initiation of treatment). Animals were killed at five time intervals (after 1.85, 3, 6, 9 and 14 months of exposure). The changes in the percentage of octaploid nuclei (8C) were used as an indicator of the kinetics of overall polyploidization. Polyploidization in control mice increased proportionally (linearly) with time (age). The enhancement of polyploidization by dieldrin was found to be proportional to dietary concentration. The slopes of the linear regressions of polyploidization, as a function of age, were identical in all dieldrin-treated groups and controls, indicating that there was no cumulative effect of dieldrin in time. A comparative analysis of the observed dieldrin dietary concentration: response relationship of polyploidization and of tumour formation in CF-1 mouse liver indicates that liver tumour formation is associated with a constant degree of polyploidization. Assuming that polyploidization reflects the ageing process, the data suggest that liver tumour formation is imminent at a constant biological age and that tumour promoters, such as dieldrin, could operate by advancing the biological age of mouse liver in the initial phases of treatment. The results of this study suggest that the analysis of ploidy changes may serve as an aid to perspective in evaluating risks associated with exposures to liver tumour promoters.

Topics: Aging; Animals; Cell Nucleus; Dieldrin; Dose-Response Relationship, Drug; Liver; Liver Neoplasms; Liver Neoplasms, Experimental; Mice; Ploidies; Receptors, Drug; Time Factors

The dose-response characteristics of dieldrin-mediated enhancement of liver tumour formation in CF-1 mice were analysed, using existing tumour data from chronic feeding studies at six levels of continuous exposure, involving a total of greater than 1500 animals. The dose-response relationship can be expressed as: Dx X Tx = D0 X T0 = constant, where T0 = the median liver tumour induction period in control CF-1 mice, Tx = the median liver tumour induction period in dieldrin-treated mice at a dose level Dx, D0 = the background dose equivalent for the induction of 'spontaneous' liver tumours, Dx = the sum of background dose (D0) and actual dieldrin dose (delta x). The relationship, which is a Druckrey equation (D X Tn = constant) where n = 1, indicates that: (i) the velocity of liver tumour development is proportional to the daily dose level (Dx), (ii) the total tumourigenic dose is constant across all doses, (iii) the effects of dieldrin on the neoplastic process in mouse liver are essentially irreversible and cumulative, and (iv) there is no evidence for a threshold level. However, when delta x much less than D0, the actual contribution of dieldrin to tumour formation is expected to be negligible.

Topics: Animals; Dieldrin; Dose-Response Relationship, Drug; Liver Neoplasms; Liver Neoplasms, Experimental; Mice

The current study was undertaken to investigate the dose-response characteristics of dieldrin-mediated enhancement of liver tumour formation in CF-1 mice. The median time to tumour development was established in controls, and in dieldrin-treated animals at six levels of continuous exposure (0.1, 1, 2.5, 5, 10 and 20 p.p.m.). The results of the analysis, which was based on liver tumour data from two parallel chronic feeding studies involving 1800 mice, are at variance with those reported by Druckrey for various established chemical carcinogens. In a double-logarithmic system of coordinates there was no linear relationship between the median total dose or the median time to tumour formation and the daily dieldrin exposure level. These results suggest that the tumourigenicity of this compound in CF-1 mouse liver is determined not by the sum of all consecutive doses, but rather by the level of daily exposure, and, presumably, the duration of treatment. This concept is consistent with the observed dose-dependency and reversible nature of dieldrin-induced subcellular changes in mouse liver. These considerations, together with evidence that dieldrin and its mammalian metabolites possess neither genotoxic activity nor potential, are not inconsistent with the concept that this compound is devoid of initiating potential, and operates by enhancing the effect of a genetically linked oncogenic factor in CF-1 mouse liver.

Topics: Adenoma; Animals; Dieldrin; Dose-Response Relationship, Drug; Female; Liver Neoplasms; Male; Mice; Mice, Inbred Strains; Neoplasms, Experimental

Mallory bodies (MBs) were observed in hepatic nodules induced by long-term administration of a diet containing 10 p.p.m. of dieldrin to C57BL/6 mice. MBs were first detected after 46 weeks and were seen in 26 of 41 mice which developed hepatic nodules. The MBs were limited to the nodules in 25 mice. Twenty-one of the nodules were carcinomas and 20 of those contained MBs. Our observations suggest that MBs may be a marker for neoplastic transformation and may prove useful in experimental studies of carcinogenesis.

Topics: Animals; Cytoskeleton; Dieldrin; Inclusion Bodies; Liver; Liver Cirrhosis; Liver Neoplasms; Male; Mice; Mice, Inbred C57BL

The effects of naturally occurring microsomal enzyme inducers on hepatocellular drug-metabolizing enzyme systems and also upon the incidence of "spontaneous" liver tumors in CF-1 mice were investigated, using animals maintained on semisynthetic diet and filter-paper bedding as controls. The administration of dieldrin, a potent microsomal enzyme inducer with tumorigenic properties in livers of CF-1 mice, to some of the experimental treatment groups served as a positive control. Conventional diet and sawdust bedding caused induction of the liver monooxygenase system, although this effect was far less pronounced than that produced by dieldrin. The incidence of liver tumors in mice exposed to conventional diet and sawdust bedding was similar to that seen in the control group. The incidence of liver tumors was significantly increased in dieldrin-treated mice, including those maintained on semisynthetic diet and filter-paper bedding. Both benign and malignant tumors were found in dieldrin-treated mice, the latter type of lesion showing evidence of lung metastasis. These results, together with evidence that dieldrin and its mammalian metabolites possess neither genotoxic activity nor potential, are consistent with the concept that dieldrin exacerbates or facilitates the expression of a preexisting oncogenic factor which is genetically linked and possibly viral in origin.

Topics: Animals; Beds; Biotransformation; Cocarcinogenesis; Dieldrin; Diet; Enzyme Induction; Liver Neoplasms; Male; Mice; Mice, Inbred Strains; Microsomes, Liver; Neoplasms, Experimental; Oxygenases

The spontaneous hepatocellular neoplasms of C3H (MTV-ve) male mice were compared with the hepatic tumors induced in these animals by diethylnitrosamine (DEN) and dieldrin. No morphologic differences could be detected by light or electron microscopy between the spontaneous and induced lesions. However, the animals given diethylnitrosamine or dieldrin developed the lesions earlier, in greater numbers and of larger size. The earliest change was the development of foci composed of clear cells. Later nodules appeared which were composed of clear or basophilic cells. These lesions were followed by and presumably progressed to nodules of trabecular hepatocellular carcinomas. It is postulated that in this series, the first morphological step in the neoplastic transformation is the appearance of unusually clear hepatocytes. Ultrastructurally, the clear cells had increased glycogen and lipid droplets and a decrease in smooth endoplasmic reticulum. The basophilic cells seen later resembled the clear cells except for having a greatly increased rough endoplasmic reticulum. Trabecular hepatocellular carcinomas differed from benign nodules in the greater secretory activity of the rough endoplasmic reticulum, in the development of basement membranes at the vascular pole and of microvilli along the lateral cell membranes. The stepwise progression of normal hepatocytes to hepatocellular carcinoma is discussed on the basis of these sequential light microscopic and ultrastructural observations.

Topics: Aging; Animals; Body Weight; Dieldrin; Diethylnitrosamine; Liver Neoplasms; Male; Mice; Mice, Inbred C3H; Neoplasms, Experimental; Nitrosamines; Organ Size; Rodent Diseases

Topics: Animals; Dieldrin; Diet; DNA; Liver; Liver Neoplasms; Mice; Organ Size; Proteins

Topics: Aldrin; Chemical Industry; DDT; Dieldrin; Humans; Insecticides; Liver Neoplasms; Occupational Diseases; Time Factors; United States

Topics: Aldrin; Animals; Carcinogens, Environmental; Dieldrin; Dogs; Dose-Response Relationship, Drug; Environmental Health; Food Contamination; Government Agencies; Haplorhini; Humans; Liver Neoplasms; Mice; Neoplasms, Experimental; Rats; United States

Topics: Adult; Animals; Carcinogens; DDT; Dieldrin; Dogs; Haplorhini; Humans; Liver Neoplasms; Male; Maximum Allowable Concentration; Mice; Microsomes, Liver; Middle Aged; Netherlands; Occupational Medicine; Phenobarbital; Rats; United Kingdom

The development of hyperplastic and neoplastic lesions of parenchymal cells of the liver adjacent to central veins was observed in C3H mice ingesting the chlorinated hydrocarbons, dieldrin or aldrin, in the diet. Lesions could be followed from pericentral hyperplasia to areas of hyperplasia, nodules of hyperplasia, small hepatocellular carcinomas, and large well-developed carcinomas, occasionally with metastases. Sometimes pericentral hyperplasia was diffuse throughout most or all of one lobe of the liver. These hyperplastic cells collided to become one large nodule and also one large carcinoma. The carcinomas were well-differentiated or moderately well-differentiated and grew on transplantation to isologous hosts. Histologically, the hyperplastic cells adjacent to central veins were increased in size, frequently with double nuclei. Carcinoma cells varied in size and shape and were huge with large nuclei, prominent nucleoli, and eosinophilic cytoplasm. Similar hepatocellular carcinomas were seen previously with carbon tetrachloride, another organochlorine chemical.

Topics: Aldrin; Animals; Carcinoma, Hepatocellular; Chemical and Drug Induced Liver Injury; Dieldrin; Female; Hepatic Veins; Hyperplasia; Liver Diseases; Liver Neoplasms; Male; Mice; Mice, Inbred C3H

The world food crisis is as critical today as when it was debated at the 1974 World Food Conference in Rome. Since the United States and Canada-and to a lesser extent, Australia and New Zealand-lead in the production of corn, wheat and soybeans, the North American "bread basket" has become the "market basket" of the world. For welfare, economic, and political reasons, our energies, resources, and deliberations must be expanded toward optimum production of wholesome food products. I do not recommend that we permit food additives in "questionably" safe or excessive concentrations in our agricultural products. I do recommend, however, that tolerance limits for food additives be established based on a comprehensive review of all contributing factors-the world food crisis and the rational interpretation of both positive and negative animal data as they relate to man. As Dr. Herbert Stokinger put it so aptly: "Avoid the establishment of unnecessarily severe standards." 2. Funds for research and teaching of food and nutrition should be greatly increased, so that all who can read and write may be made aware of the daily dietary requirements for the maintenance of good health. 3. Unsubstantiated scare tactics in publications of the scientific and lay press can only lead to well-intended but often emotionally-inspired restrictions, ordinances, and laws. Such decisions are likely to either under- or over-define the requirements and standards for food additives and other chemicals which are important to the well-being of the populace.

Topics: Aldrin; Animals; Carcinogens; DDT; Dieldrin; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Tolerance; Feeding Behavior; Food; Food Additives; Food Supply; History of Medicine; Humans; Liver Neoplasms; Mice; Nutritional Physiological Phenomena; Population; Research Design; Species Specificity; United States

Topics: Aldrin; Animals; Dieldrin; Humans; Legislation, Drug; Liver Neoplasms; Mice; United Kingdom; United States

Topics: Adult; Age Factors; Animals; Carcinogens; Dieldrin; Environmental Exposure; Humans; Infant; Infant, Newborn; Liver Neoplasms; Maximum Allowable Concentration; Mice; Neoplasms; United States

Topics: Animals; Carcinogens; Dieldrin; Liver Neoplasms; Lung Neoplasms; Mice; Mice, Inbred Strains; Risk

Topics: Administration, Oral; Animals; DDT; Dieldrin; Female; Hepatomegaly; Hexachlorocyclohexane; Hyperplasia; Liver; Liver Neoplasms; Male; Mice; Microsomes, Liver; Mortality; Neoplasm Metastasis; Phenobarbital; Time Factors

Topics: Administration, Oral; Animals; Body Weight; Carcinoma, Hepatocellular; Chemical and Drug Induced Liver Injury; DDT; Dieldrin; Female; Hepatomegaly; Liver Neoplasms; Male; Mice; Mortality; Neoplasm Metastasis; p-Dimethylaminoazobenzene; Sarcoma; Sterilization; Time Factors

Topics: Adipose Tissue; Arteriosclerosis; Brain Chemistry; Brain Neoplasms; Cerebral Hemorrhage; Chromatography, Gas; DDT; Dichlorodiphenyldichloroethane; Dieldrin; Encephalomalacia; Humans; Hypertension; Kidney Diseases; Liver; Liver Cirrhosis; Liver Diseases; Liver Neoplasms; Pesticides; Statistics as Topic