Adipose tissue concentrations of p,p'-DDE and the risk for endometrial cancer.

OBJECTIVE: To evaluate in a case-control study possible risk of endometrial cancer associated with environmental endocrine disruptors. METHODS: We analyzed the adipose tissue concentrations of polychlorinated biphenyls, hexachlorobenzene (HCB), p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE), chlordanes, and polybrominated biphenyls in 76 cases with endometrial cancer and 39 controls with benign endometrial hyperplasia. RESULTS: For the different chemicals, odds ratios (ORs) and 95% confidence intervals (CI) were close to unity taking the median concentration among the controls as cutoff value. However, for p,p'-DDE OR = 1.9, 95% CI = 0.8-4.8 was obtained. Additional estrogen replacement therapy yielded in this category OR = 2.3, 95% CI = 0.6-8.6. CONCLUSION: The results suggest an interaction between p,p'-DDE and estrogen replacement drugs in the etiology of endometrial cancer, although no significant associations were found.

Increased concentrations of polychlorinated biphenyls, hexachlorobenzene, and chlordanes in mothers of men with testicular cancer.

An increasing incidence of testicular cancer has been reported from several countries in the Western world during the last decades. According to current hypothesis, testicular cancer is initiated during the fetal period, and exposure to endocrine disruptors, i.e., xenoestrogens, has been of concern. In this investigation we studied the concentrations of the sum of 38 polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene, hexachlorobenzene (HCB), and chlordanes, in 61 cases with testicular cancer and 58 age-matched controls. Furthermore, case and control mothers were also asked to participate, and 44 case mothers and 45 control mothers agreed. They were of similar age. In cases only the concentration on lipid basis of cis-nonachlordane was significantly increased, whereas case mothers showed significantly increased concentrations of the sum of PCBs, HCB, trans- and cis-nonachlordane, and the sum of chlordanes. Among case mothers the sum of PCBs yielded an odds ratio (OR) of 3.8; 95% confidence interval (CI), 1.4-10 was calculated using the median concentration for the control mothers as cutoff value. For HCB, OR = 4.4 (95% CI, 1.7-12); for trans-nonachlordane, OR = 4.1 (95% CI, 1.5-11); for cis-nonachlordane, OR = 3.1 (95% CI, 1.2-7.8); and for sum of chlordanes, OR = 1.9 (95% CI, 0.7-5.0). No consistent different risk pattern was found for seminoma or nonseminoma testicular cancer.

Toxic disputes and the rise of environmental justice in Australia.

The paper examines the rise of environmental justice issues in Australia, evident in two toxic disputes; the first, in a Perth outer suburb in Western Australia where residents faced both a hazardous waste dump and the nation's biggest chemical fire; and the second, in the Sydney suburb of Botany where residents were confronted with the destruction of what is thought to be, the world's largest stockpile of hazardous hexachlorobenzene (HCB) waste. The paper reviews the range of factors that impacted the local communities' fight for environmental justice. It explores the limitations of risk assessment and risk-based policies, as well as the problematic role of the expert and the communication of risk. The informational inequity and resource disparities so evident in toxic disputes are highlighted. The case studies confirmed the inequitable distribution of chemical risk as a failure to secure environmental justice for all Australians.

The role of the immune system in hexachlorobenzene-induced toxicity.

Hexachlorobenzene (HCB) is a persistent environmental pollutant. The toxicity of HCB has been extensively studied after an accidental human poisoning in Turkey and more recently it has been shown that HCB has immunotoxic properties in laboratory animals and probably also in man. Oral exposure of rats to HCB showed stimulatory effects on spleen and lymph node weights and histology, increased serum IgM levels, and an enhancement of several parameters of immune function. Moreover, more recent studies indicate that HCB-induced effects in the rat may be related to autoimmunity. In Wistar rats exposed to HCB, IgM antibodies against several autoantigens were elevated; in the Lewis rat, HCB differently modulated two experimental models of autoimmune disease. Oral exposure of rats to HCB induces skin and lung pathology in the rat. Recently several studies have been conducted to investigate whether these skin and lung lesions can be related to HCB-induced immunomodulation, and these studies will be discussed in this review. HCB-induced skin and lung lesions probably have a different etiology; pronounced strain differences and correlation of skin lesions with immune parameters suggest a specific involvement of the immune system in HCB-induced skin lesions. The induction of lung lesions by HCB was thymus independent. Thymus-dependent T cells were not likely to be required for the induction of skin lesions, although T cells enhanced the rate of induction and the progression of the skin lesions. No deposition of autoantibodies was observed in nonlesional or lesional skin of HCB-treated rats. Therefore, we concluded that it is unlikely that the mechanism by which most allergic or autoimmunogenic chemicals work, i.e., by binding to macromolecules of the body and subsequent T- and B-cell activation, is involved in the HCB-induced immunopathology in the rat. Such a thymus-independent immunopathology is remarkable, as HCB strongly modulates T-cell-mediated immune parameters. This points at a very complex mechanism and possible involvement of multiple factors in the immunopathology of HCB.

Hexachlorobenzene, a dioxin-type compound, increases malic enzyme gene transcription through a mechanism involving the thyroid hormone response element.

Hexachlorobenzene (HCB) is a dioxin-type chemical that acts mainly through the aryl hydrocarbon receptor. Chronic exposure of rats to HCB increases the activity of malic enzyme (ME). In this report, we show that this increase is correlated with an induction of ME messenger RNA (mRNA) levels, with the maximal HCB effect achieved after 9 days of intoxication. This effect is specific for ME, as other liver enzymes, such as glyceraldehyde-3-phosphate dehydrogenase, phosphoenol pyruvate carboxykinase, and mitochondrial alpha-glycerol-3-phosphate dehydrogenase, are not affected by HCB. The induction of ME mRNA levels is accompanied by an increase in ME promoter activity, as demonstrated by transient transfection experiments performed in rat hepatoma H35 cells. In an attempt to identify the cis-regulatory elements responsible for the HCB effect, different promoter deletions and mutations were used. The results obtained localize the responsive region between positions -315 and -177. This region does not contain either consensus xenobiotic response or activating protein-1 elements, the two main mediators of dioxin compounds described to date. In contrast, a thyroid hormone response element (TRE) is located between -281 to -261. Deletions and mutations of the TRE element do not respond to HCB, demonstrating that this element mediates the response of this dioxin-type compound. As ME gene expression is regulated mainly by thyroid hormones, we next investigated the role of T3 receptor (T3R) in the ME gene transcriptional induction mediated by HCB. Using Scatchard analysis, we show that neither T3R binding features for its ligand nor alpha1 or beta1T3R mRNA levels are changed with the toxic. In gel shift assays, however, we observed that protein/DNA complexes formed on TRE from the ME promoter were induced by HCB. Using an oligonucleotide with a mutation that eliminates the TRE function, we demonstrate a loss of the induced protein/DNA complexes. Together, these data suggest that the dioxin-type compound HCB increases ME gene transcription by modulating the levels of still unidentified nuclear proteins that bind to the TRE element of the ME promoter.

[Effect of thyroid hormones on the modulation of genetic expression of liver cytosolic malic enzyme, in rats poisoned with hexachlorobenzene]. / Acción de las hormonas tiroideas sobre la modulación de la expresión genética de la enzima málica citosólica hepática, en ratas intoxicadas con hexaclorobenceno.

Hexachlorobenzene (HCB) is a widespread environmental pollutant. Chronic exposure of laboratory animals to HCB triggers porphyria, induction of liver microsomal enzymes, low levels of T4 reproductive dysfunction's, liver and thyroid tumors. Previous findings from our laboratory have shown that HCB increased the activity of the liver thyroid-responsive enzymes: malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PD) without any change in the mytochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD). In this study we have demonstrated that HCB treatment increased ME mRNA. We also have investigated if HCB affected: a) the thyroid hormone receptor (TR) concentration and binding affinity for its ligands, b) specifically the ME gene expression, or other thyroid hormone responsive enzymes were affected as well, c) Protein/DNA complex formed on the thyroid responsive element (TRE). Livers from female Wistar rats intoxicated with HCB (100 mg/100 g b.w.), for 9 and 15 days, were analyzed. Northern blot hybridization analysis, have demonstrated that ME mRNA levels increased 4 times and 2 times after 9 and 15 days intoxication respectively, without any alterations in the mRNA levels of other thyroid hormone responsive enzymes such as glyceraldheyde 3- phosphate dehydrogenase, phosphoenolpyruvatecarboxikinase and alpha-GPD. These results suggest that HCB affects specifically, ME gene expression. Hepatic T3 and T4 levels evaluated by RIA were not affected by HCB. Scatchard analyses showed that TR affinity and number of sites were not altered after 9 and 15 days of HCB treatment (control, Ka: 1.9 nM, Bmax 3.9 f/mol 100 micrograms DNA: HCD 9 days Ka: 2.1 nM, Bmax 4.5 fmol/100 micrograms DNA: HCB 15 days Ka 1.9 nM. Bmax 5.1 fmol/100 micrograms DNA intoxication, neither at 9 nor at 15 days. Electrophoresis mobility shift assay showed that HCB did not modify nuclear protein extract affinity for the TREs sequence. Our results suggest that TR itself was not directly involved in the induction of ME gene expression by HCB. Nevertheless TR could interact with other transcription factors in the overexpression of ME gene.

Isolation and characterization of new porphyrin metabolites in human porphyria cutanea tarda and in rats treated with hexachlorobenzene by HPTLC, HPLC and liquid secondary ion mass spectrometry.

Porphyrin metabolisms in human porphyria cutanea tarda (PCT) and in rats treated with hexachlorobenzene (HCB) have been studied in detail by high performance thin layer chromatography (HPTLC), high performance liquid chromatography (HPLC) and liquid secondary ion mass spectrometry (LSIMS). The analyses of porphyrin metabolites in the urine, faeces and liver biopsies of patients with PCT have shown that apart from uroporphyrin I and III and their expected decarboxylation intermediates and products, a complex mixture of many other porphyrins are present. The new porphyrins identified are: meso-hydroxyuroporphyrin III, beta-hydroxypropionic acid uroporphyrin III, hydroxyacetic acid uroporphyrin III, peroxyacetic acid uroporphyrin III, beta-hydroxyproionic acid heptacarboxylic acid porphyrin III, hydroxyacetic acid hepatocarboxylic porphyrin III and peroxyacetic acid pentacarboxylic porphyrin III.

Organochlorine and mercury contamination in United Kingdom seals.

In 1988 and 1989 tissue samples were obtained from the grey seal (Halichoerus grypus) population found in the Dee estuary in the north west of England and from harbour seals (Phoca vitulina) from the populations in the Wash and north east Scotland and analysed for mercury and organochlorine compounds. Adult seals from the Dee estuary were highly contaminated with mercury and polychlorinated biphenyls (PCBs), and one animal from the Dee contained traces of dichlorodiphenyltrichloroethane (DDT), suggesting the recent use of this banned pesticide. The levels of hexachlorobenzene in the livers of two Dee seals exceeded those in the blubber, possibly indicating liver malfunction or recent exposure. The same relationship was found for hexachlorobenzene in three specimens from the Wash and, in one of these animals, the liver was also more highly contaminated than the blubber with dieldrin and PCBs. Levels of contamination were lower in seals from the Wash and even lower in animals sampled in Scotland, where only dichlorophenyldichloroethylene, the metabolite of DDT, was routinely detected. The toxicological significance of the results is discussed, particularly in relation to the mortality observed in the seal epizootic of 1988.

Is hexachlorobenzene human overload related to porphyria cutanea tarda? A speculative hypothesis.

After the epidemic outbreak of Porphyria Turcica from 1955 to 1961, the porphyrinogenic effect of hexachlorobenzene (HCB) on humans and animals has been fully confirmed. HCB is an environmental contaminant originated from its use as fungicide or obtained as a by product from industrial residues. Measurement of HCB levels in adipose tissue and maternal milk is a useful tool for monitoring its body stores which are clearly higher in Spain than in other European or American countries. At least in the Spanish area of Catalunya, the HCB fat tissue concentration decreased from more than 5 ppm in 1981-1982 to less than 3 ppm in 1986-1987. Porphyria cutanea tarda is a relatively frequent disease in Spain. More than 700 cases were observed in Madrid from 1964 to 1988. Before 1970, less than 10 cases were annually detected, a figure that rose up to 60-70 annual cases from 1977 to 1982 and decreased to less than 25 annual cases from 1985 to 1988. Based on all these previous data, a speculation is tempting: the high and variable incidence of porphyria cutanea tarda in Spain may be related to environmental contamination with HCB.

Hexachlorobenzene episode in Turkey.

During the period 1955-1959, approximately 4000 people in southeast Anatolia developed porphyria due to the ingestion of hexachlorobenzene (HCB), a fungicide added to wheat seedlings. These HCB exposures subsequently led to the development of bullae on sun-exposed areas, hyperpigmentation, hypertrichosis, and porphyrinuria. The condition was called kara yara or "black sore." Many of the breast-fed children under the age of 2 years whose mothers had ingested HCB-treated grain died from a disease known as pembe yara or "pink sore." In this follow-up study of 252 patients, 20-30 years postexposure, there were 162 males and 90 females, with an average current age of 35.7 years, an average of onset of 7.6 years, and a duration of 2.2 years. Many patients had dermatologic, neurologic, and orthopedic symptoms and signs. The observed clinical findings include scarring of the face and hands (83.7%), hyperpigmentation (65%), hypertrichosis (44.8%), pinched facies (40.1%), painless arthritis (70.2%), small hands (66.6%), sensory shading (60.6%), myotonia (37.9%), cogwheeling (41.9%), enlarged thyroid (34.9%), and enlarged liver (4.8%). Urine and stool porphyrin levels were determined in all patients, and 17 have at least one of the porphyrins elevated. A total of 56 specimens of human milk obtained from mothers with porphyria were analyzed for HCB. The average value was 0.51 ppm in HCB-exposed patients compared to 0.07 ppm in unexposed controls. Offspring of mothers with three decades of HCB-induced porphyria appear normal.

Exposure of man to environmental hexachlorobenzene (HCB)--an exposure commitment assessment.

Hexachlorobenzene (HCB) is widely distributed and has high persistence in the environment. In the 1970s restrictions on its use as a fungicide for cereal grains were initiated, but there are other uses and releases from chemical manufacturing industries and waste disposal operations. Representative values for HCB in environmental media and in man have been used in an exposure commitment assessment. The human body burden of HCB, estimated at 0.7 mg, is derived mainly from dietary intake of fatty foods, diet contributing approximately 0.2 microgram day-1. Inhalation is estimated to contribute about two orders of magnitude less. The assessment indicates a low exposure to HCB from the general environment, but populations exposed to direct contamination have had increased intake via one or both pathways.

Mechanistic studies of the inhibition of hepatic uroporphyrinogen decarboxylase in C57BL/10 mice by iron-hexachlorobenzene synergism.

Porphyria was induced in C57BL/10 mice with iron overload by a single oral dose (100 mg/kg) of hexachlorobenzene (HCB). Within 2 weeks hepatic uroporphyrinogen decarboxylase (EC 4.1.1.37) was inhibited, reaching a maximum (greater than 95%) at 6-8 weeks. There was no recovery by 14 weeks, despite a fall in liver HCB concentrations to only 6% of the day-3 value. The major rise in hepatic porphyrin levels occurred after 4 weeks and secondary inhibition of uroporphyrinogen synthase (EC 4.2.1.75) was inferred from the progressively greater proportion of uroporphyrin I present relative to the III isomer. Plasma alanine aminotransferase (EC 2.6.1.2) activity was also elevated. Although, in further studies, total microsomal cytochrome P-450 content and ethoxyphenoxazone de-ethylase activity reached a peak a few days after dosing and had declined significantly at the time of maximum inhibition of the decarboxylase, additional treatment of HCB-dosed mice with a cytochrome P1-450 inducer, beta-naphthoflavone, enhanced the inhibition, whereas piperonyl butoxide, an inhibitor of cytochrome P-450, partially protected. Uroporphyrinogen decarboxylase was not radiolabelled in vivo by [14C]HCB. There was no major difference in the ability to hydroxylate HCB between hepatic microsomes from induced C57BL/10 mice and those from the insensitive DBA/2 strain. By contrast, lipid peroxidation, in the presence of NADPH, was 8-fold greater in control C57BL/10 microsomes than in DBA/2 microsomes and was stimulated by iron treatment (although not by HCB). The results suggest that the inhibition of hepatic uroporphyrinogen decarboxylase is unlikely to be due to a direct effect of a metabolite of HCB but to another process requiring a specific cytochrome P-450 isoenzyme and an unknown iron species.

Porphyria cutanea tarda, or the uroporphyrinogen decarboxylase deficiency diseases.

The term "porphyria cutanea tarda" originally described the dermatological manifestations of various chronic porphyrias. Its usage now is usually restricted to disorders associated with a deficiency of uroporphyrinogen decarboxylase (UROD), for which the term "UROD-deficiency" may be more appropriate. Four etiologic agents have been implicated in this condition: alcohol, oral estrogens, halogenated aromatic hydrocarbons, and iron. An inherited deficiency of UROD is also recognized, with increased susceptibility to these agents. Certain halogenated aromatic hydrocarbons can cause UROD-deficiency in animals and synergism with iron is demonstrable in this model. Neither ethanol nor estrogen has been shown to cause UROD-deficiency in animals. Treatment by venesection to reduce total body iron is safe and effective. The 4-aminoquinoline antimalarial drugs also provide effective treatment, possibly by lysis of affected liver cells. Unlike venesection, they may not reverse the biochemical lesion which causes porphyrins to accumulate. The mechanism of acquired UROD-deficiency is not clear but animal studies suggest a role for the hepatic mixed function oxygenases which initiate iron-dependent inactivation of UROD. Diagnosis is simple, often requiring only appropriate clinical data and testing of a random urine sample. Although not common, the disorder is the most frequently diagnosed disturbance of porphyrin metabolism in many countries, and further insight into its unusual pathogenesis may clarify the hepatotoxic effects of the 4 etiologic agents.

Effects of antioxidants on the TBA reaction of various rat liver homogenates.

The TBA reaction of physiologically normal (young and aged) rat liver homogenate appears to be catalyzed mainly by nonheme iron which is sensitive to EDTA, whereas some iron species which are not affected by EDTA seem to be functioning as catalysts in the TBA reaction of drug-intoxicated (CCl4, HCB) liver homogenates.

[Increased lysosomal membrane permeability in hexachlorobenzene poisoning in rabbits]. / Povyshenie pronitsaemosti lizosomal'nykh membran pri intoksikatsii geksakhlorbenzenom u krolikov.

To assess the effect of the fungicide hexachlorobenzene (HCB) on lysosomal membrane stability in rabbits, the authors determined the activity of two lysosomal enzymes (beta-N-acetylglucosaminidase, CP 3.2.1.30 and alpha-mannosidase, CP 3.2.1.24) in the blood serum, and free unsedimentable activity of the former enzyme in liver homogenates. The activities of beta-N-acetylglucosaminidase and alpha-mannosidase were found to be enhanced on the 7th and 50th days after daily administration of HCB in doses 280 and 105 mumol/kg body mass, respectively. In chronic experiments, there was also an increase in free and unsedimentable activity of beta-N-acetylglucosaminidase in liver homogenates. Increased permeability of lysosomal membranes due to HCB indicates that lysosomes and acid hydrolases are implicated in the pathogenesis of intoxication under consideration.

Gamma-glutamyl transferase: a sensitive marker in experimental hexachlorobenzene intoxication.

The behaviour of gamma-glutamyl transferase (gamma-GT) in rat liver, serum and intestinal mucosa under the effect of hexachlorobenzene (HCB) was studied. The investigation was carried out in order to evaluate gamma-GT as a biological parameter in experimental HCG porphyria. HCB was administered by gavage at daily doses of 3.5 mmol/kg body wt for 60 days or 90 days. gamma-GT in liver homogenate progressively increased during the treatment. Following a 60-day exposure the enzymatic activity exceeded the values of the controls by more than 60 times. The rise of serum gamma-GT was more moderately expressed (5--6-fold). gamma-GT in jejunal mucosa was elevated 2-fold after a 90-day treatment. The termination of the daily intoxication reduced back to normal values the enzymatic activity in liver and in intestine as measured after 60 days from the cessation of HCB application. It can be pointed out, that gamma-GT is a sensitive and valuable marker for experimental HCB intoxication.