Lung Cancer in an Orthoprosthetist Using Vermiculite

Occupational exposure to certain substances would cause cancer. Herein, we report on a case of a 58-year-old former orthoprostethist who died from a lung adenocarcinoma. He had a 3 pack-year history of smoking and a single exposure to asbestos during his professional career. Between 1979 and 2010, he used vermiculite plaques daily to build medical prostheses, using no personal protective equipment. Contamination of vermiculite with amphibole asbestos has been described in Libby, Montana. Expert opinion on this case has raised the hypothesis of the use of this kind of vermiculite during this period and the occupational etiology of this cancer. It seems important to point out the possibility of vermiculite-related lung cancers in unusual occupations in order to better document such cases in the future.

Evaluation of Efficacy and Toxicity of Exfoliated Silicate Nanoclays as a Feed Additive for Fumonisin Detoxification

The efficacy of nanosilicate clay platelets (NSCP), exfoliated silicates from natural montmorillonites, as a feed additive for ameliorating fumonisin B1 (FB1) toxicosis was evaluated. Toxicological mechanisms by NSCP were examined through proteomic and biochemical analyses. Dietary supplementation with NSCP at a low level of 40 mg/kg of feed improved growth performances in chickens with respect to FB1 toxicosis. Other issues of ameliorated symptoms including serum and/or hepatic aspartate aminotransferase activity, oxidative stress indicators, and sphinganine/sphingosine ratio, a hallmark of FB1 toxicosis, were considered. Chickens with NSCP inclusion alone at 1000 mg/kg of feed exhibited no changes in hepatic histology, oxidative status, and serum parameters and even had a higher feed intake. Proteomic analysis with liver tissues identified 45 distinct proteins differentially affected by FB1 and/or NSCP, in which proteins involved in thiol metabolism and redox regulation, glycolysis, carcinogenesis, and detoxification by glutathione S-transferase were promoted by FB1, whereas NSCP caused differential changes of protein abundances related to methionine/cysteine and choline/glycine interconversion for glutathione synthesis, redox regulation by peroxiredoxin, toxin/metabolite delivery by albumin, glycolysis, tricarboxylic acid cycle, adenosine triphosphate (ATP) synthesis, and chaperon escort for endoplasmic reticulum stress relief. Functional analyses confirmed the enhancement of hepatic metabolic processes for ATP and NAD(P)H production to meet the need for detoxification, antioxidative defense, and toxin/metabolite clearance by FB1 or NSCP ingestion. On the basis of the amelioration of FB1 toxicosis, global profile of hepatic protein expressions, and validated toxicological mechanisms, NSCP were concluded as a safe and effective agent for FB1 detoxification.

Pleuroparenchymal fibroelastosis associated with aluminosilicate dust: a case report

Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a recently described rare condition, characterized by pleural and subpleural parenchymal fibrosis, predominantly in the upper lobes. The clinical course of this disease is progressive and prognosis is poor, with little information regarding the etiology of IIPPFE. This report describes an IPPFE patient with convincing evidence of inhalational dust and suggests that dust exposure should be considered as a new causative factor of IPPFE.

Effect of Clinoptilolite and Sepiolite Nanoclays on Human and Parasitic Highly Phagocytic Cells

Nanoclays have potential applications in biomedicine raising the need to evaluate their toxicity in in vitro models as a first approach to its biocompatibility. In this study, in vitro toxicity of clinoptilolite and sepiolite nanoclays (NC) was analyzed in highly phagocytic cultures of amoebas and human and mice macrophages. While amebic viability was significantly affected only by sepiolite NC at concentrations higher than 0.1 mg/mL, the effect on macrophage cultures was dependent on the origin of the cells. Macrophages derived from human peripheral blood monocytes were less affected in viability (25% decrease at 48 h), followed by the RAW 264.7 cell line (40%), and finally, macrophages derived from mice bone marrow monocytes (98%). Moreover, the cell line and mice macrophages die mainly by necrosis, whereas human macrophages exhibit increased apoptosis. Cytokine expression analysis in media of sepiolite NC treated cultures showed a proinflammatory profile (INFγ, IL-1α, IL-8, and IL-6), in contrast with clinoptilolite NC that induced lees cytokines with concomitant production of IL-10. The results show that sepiolite NC is more toxic to amoebas and macrophages than clinoptilolite NC, mostly in a time and dose-dependent manner. However, the effect of sepiolite NC was comparable with talc powder suggesting that both NC have low cytotoxicity in vitro.

Muscovite is protective against non-steroidal anti-inflammatory drug-induced small bowel injury

AIM: To evaluate the effect of muscovite in preventing small bowel injury induced by nonsteroidal anti-inflammatory drugs (NSAIDs).

METHODS: We recruited and screened thirty-two healthy volunteers who were randomly allocated equally into two groups: an NSAID control group, who received 75 mg slow-release diclofenac, twice daily for 14 d; and an NSAID-muscovite group, who received 3 g of muscovite in addition to the 75 mg of slow-release diclofenac, twice daily for 14 d. For gastroprotection, both groups were administered 20 mg/d of the proton pump inhibitor omeprazole. All eligible subjects underwent video capsule endoscopy (CE) prior to and 14 d after treatment.

RESULTS: Thirty subjects (NSAID-muscovite group, n =16; NSAID control group, n =14) finally completed the whole trail. At the baseline CE examination, no statistically significant differences between the two groups have been observed. However, after 14 d of drug treatment, a significant difference was observed in the percentage of subjects with mucosal breaks when comparing the NSAID-muscovite group with the NSAID control group. While 71.4% (10/14) of subjects in the NSAID control group had at least one mucosal break, co-administration of muscovite in the NSAID-muscovite group reduced the rate to 31.3% (5/16) (P = 0.028). Moreover, higher number of mucosal breaks was found in the NSAID control group vs that in the NSAID-muscovite group (P < 0.05).

CONCLUSION: Muscovite co-therapy reduced the incidence of small intestinal injury after 14 d of diclofenac administration.

Meat and bone meal and mineral feed additives may increase the risk of oral prion disease transmission

Ingestion of prion-contaminated materials is postulated to be a primary route of prion disease transmission. Binding of prions to soil (micro)particles dramatically enhances peroral disease transmission relative to unbound prions, and it was hypothesized that micrometer-sized particles present in other consumed materials may affect prion disease transmission via the oral route of exposure. Small, insoluble particles are present in many substances, including soil, human foods, pharmaceuticals, and animal feeds. It is known that meat and bone meal (MBM), a feed additive believed responsible for the spread of bovine spongiform encephalopathy (BSE), contains particles smaller than 20 μm and that the pathogenic prion protein binds to MBM. The potentiation of disease transmission via the oral route by exposure to MBM or three micrometer-sized mineral feed additives was determined. Data showed that when the disease agent was bound to any of the tested materials, the penetrance of disease was increased compared to unbound prions. Our data suggest that in feed or other prion-contaminated substances consumed by animals or, potentially, humans, the addition of MBM or the presence of microparticles could heighten risks of prion disease acquisition.

Potency factors for risk assessment at Libby, Montana

We reanalyzed the Libby vermiculite miners' cohort assembled by Sullivan to estimate potency factors for lung cancer, mesothelioma, nonmalignant respiratory disease (NMRD), and all-cause mortality associated with exposure to Libby fibers. Our principal statistical tool for analyses of lung cancer, NMRD, and total mortality in the cohort was the time-dependent proportional hazards model. For mesothelioma, we used an extension of the Peto formula. For a cumulative exposure to Libby fiber of 100 f/mL-yr, our estimates of relative risk (RR) are as follows: lung cancer, RR = 1.12, 95% confidence interval (CI) =[1.06, 1.17]; NMRD, RR = 1.14, 95% CI =[1.09, 1.18]; total mortality, RR = 1.06, 95% CI =[1.04, 1.08]. These estimates were virtually identical when analyses were restricted to the subcohort of workers who were employed for at least one year. For mesothelioma, our estimate of potency is K(M) = 0.5 x 10(-8), 95% CI =[0.3 x 10(-8), 0.8 x 10(-8)]. Finally, we estimated the mortality ratios standardized against the U.S. population for lung cancer, NMRD, and total mortality and obtained estimates that were in good agreement with those reported by Sullivan. The estimated potency factors form the basis for a quantitative risk assessment at Libby.

Migration of aluminum silicate from the oral cavity to the submandibular region, with foreign body granuloma formation: report of a case

We present the first case of foreign body granuloma in the cervical (submandibular) region as a result of migration of noninjected aluminium silicate particles from the oral mucosa. This migration can be explained by macrophage phagocytosis and transport through the local lymphatic network and surgical disruption of fascial layers. The appearance of foreign body granulomas in distant sites may appear several weeks after the local event in a specific disposition according with the migration route. This entity must be born in mind in differential diagnosis of multiple nodules, pigmentation, or persistent swelling in the cervical-orofacial region.

Pleuroparenchymal lung disease secondary to nonoccupational exposure to vermiculite

An unusual case of pleuroparenchymal lung disease caused by the inhalation of vermiculite dust, presumably containing asbestos fibers is described. The uniqueness of the case lies in the very indirect nature of exposure -- the wife of a factory owner, rather than a worker exposed to asbestos, whose factory manufactured vermiculite. The present case illustrates the importance of taking careful occupational histories of all household members when presented with a patient whose chest radiograph exhibits features consistent with asbestos exposure.

Vermiculite, respiratory disease, and asbestos exposure in Libby, Montana: update of a cohort mortality study

BACKGROUND

Vermiculite from the mine near Libby, Montana, is contaminated with tremolite asbestos and other amphibole fibers (winchite and richterite). Asbestos-contaminated Libby vermiculite was used in loose-fill attic insulation that remains in millions of homes in the United States, Canada, and other countries.

OBJECTIVE

This report describes asbestos-related occupational respiratory disease mortality among workers who mined, milled, and processed the Libby vermiculite.

METHODS

This historical cohort mortality study uses life table analysis methods to compare the age-adjusted mortality experience through 2001 of 1,672 Libby workers to that of white men in the U.S. population.

RESULTS

Libby workers were significantly more likely to die from asbestosis [standardized mortality ratio (SMR) = 165.8; 95% confidence interval (CI), 103.9-251.1], lung cancer (SMR = 1.7; 95% CI, 1.4-2.1), cancer of the pleura (SMR = 23.3; 95% CI, 6.3-59.5), and mesothelioma. Mortality from asbestosis and lung cancer increased with increasing duration and cumulative exposure to airborne tremolite asbestos and other amphibole fibers.

CONCLUSIONS

The observed dose-related increases in asbestosis and lung cancer mortality highlight the need for better understanding and control of exposures that may occur when homeowners or construction workers (including plumbers, cable installers, electricians, telephone repair personnel, and insulators) disturb loose-fill attic insulation made with asbestos-contaminated vermiculite from Libby, Montana.

An evaluation of wear when enamel is opposed by various ceramic materials and gold

STATEMENT OF PROBLEM

Ceramic restorations have been known to cause wear of opposing enamel.

PURPOSE

The purpose of this study was to evaluate enamel wear caused by 3 ceramic substrates in the glazed and polished conditions.

MATERIAL AND METHODS

Sixty ceramic discs (10 x 2 mm)-20 each of Finesse, All-Ceram, and IPS-Empress-were prepared and glazed. Each group of 20 was divided into 2 groups of 10. The surfaces of one group were ground and polished using a porcelain polishing kit (Dialite). The remaining 10 were left as glazed. Ten specimens of a type III gold alloy were cast into rectangular shapes of 10 x 12 x 2 mm and polished. Seventy human cusps were prepared from sound, caries-free, extracted teeth and abraded against the substrates in a wear machine for a total of 10,000 cycles. The cusp height loss was traced before and after the wear test using a profile projector. Mean surface roughness (R(a)) values for the substrates were also recorded with a profilometer before testing. Differences in R(a) were evaluated using 1- and 2-way ANOVA and the Scheffe post hoc test (alpha = .05).

RESULTS

One-way ANOVA indicated that enamel height loss was significantly different by material (P < .001) and surface condition (glazed and polished or glazed; P < .05). Gold, polished Finesse, and polished All-Ceram were the least abrasive, whereas glazed IPS-Empress was the most abrasive. There was no significant interaction effect between substrate type and surface condition. Significant differences were found when R(a) of the substrate condition was compared with enamel wear (P < .01).

CONCLUSIONS

Gold, polished Finesse, and polished All-Ceram caused the least enamel wear, whereas IPS-Empress caused the most wear. Cast gold was significantly different than glazed IPS-Empress (P < .05), whereas other groups overlapped. There was significant correlation between R(a) and enamel wear (P < .01).

Nested case-control study of autoimmune disease in an asbestos-exposed population

OBJECTIVE

To explore the potential association between asbestos exposure and risk of autoimmune disease, we conducted a case-control study among a cohort of 7,307 current and former residents of Libby, Montana, a community with historical occupational and environmental exposure to asbestos-contaminated vermiculite.

METHODS

Cases were defined as those who reported having one of three systemic autoimmune diseases (SAIDs): systemic lupus erythematosus, scleroderma, or rheumatoid arthritis (RA). Controls were randomly selected at a 3:1 ratio from among the remaining 6,813 screening participants using frequency-matched age and sex groupings.

RESULTS

The odds ratios (ORs) and 95% confidence intervals (CIs) for SAIDs among those >or=65 years of age who had worked for the vermiculite mining company were 2.14 (95% CI, 0.90-5.10) for all SAIDs and 3.23 (95% CI, 1.31-7.96) for RA. In this age group, exposure to asbestos while in the military was also an independent risk factor, resulting in a tripling in risk. Other measures of occupational exposure to vermiculite indicated 54% and 65% increased risk for SAIDs and RA, respectively. Those who had reported frequent contact with vermiculite through various exposure pathways also demonstrated elevated risk for SAIDs and RA. We found increasing risk estimates for SAIDs with increasing numbers of reported vermiculite exposure pathways (p<0.001).

CONCLUSION

These preliminary findings support the hypothesis that asbestos exposure is associated with autoimmune disease. Refined measurements of asbestos exposure and SAID status among this cohort will help to further clarify the relationship between these variables.

Symptomatic efficacy of beidellitic montmorillonite in irritable bowel syndrome: a randomized, controlled trial

BACKGROUND

Beidellitic montmorillonite is a purified clay containing a double aluminium and magnesium silicate.

AIM

To assess the efficacy and the safety of beidellitic montmorillonite (3 g, t.d. for 8 weeks) in patients with irritable bowel syndrome (IBS).

METHODS

A multicentre, double-blind, placebo-controlled, randomized study with parallel groups, was performed in IBS patients selected according to ROME I criteria. Patients were included after a 1-week washout period to confirm that abdominal pain and/or discomfort was rated at least 2 on a 0-4 graded Likert scale. Patients were then randomized and stratified according to their predominant bowel habit profile into three groups. The use of rescue medication was allowed: polyethylene glycol 4000 (10-20 g/day) as a laxative agent in case of stool absence for three consecutive days, phloroglucinol (80 to a maximum of 320 mg/day) as a spasmolytic agent for no more than 8 days. The main end-point was the improvement of abdominal pain and/or discomfort by at least 1 point on the Likert scale.

RESULTS

A total of 524 patients constituted the overall intent-to-treat population (ITT), 263 were assessed in the beidellitic montmorillonite group, i.e. 93 diarrhoea-predominant IBS (D-IBS), 83 constipation-predominant IBS (C-IBS), 87 alternating constipation/diarrhoea-IBS (A-IBS); 261 in the placebo group, i.e. 81 D-IBS, 92 C-IBS and 88 A-IBS. Initial analysis in the ITT population demonstrated a higher rate of success with beidellitic montmorillonite (51.7%) when compared with the placebo group (45.2%); however, the difference was not statistically significant. Improvement was significant in C-IBS both in ITT (beidellitic montmorillonite group = 49.4%, placebo group = 31.5%, P < 0.016) and per protocol populations (59.4% vs. 37.8%) (P < 0.01). The time to improvement of abdominal pain and/or discomfort (log Rank test) was also significantly in favour of beidellitic montmorillonite, (P < 0.04). The average number of stools per day was not different from baseline, either in all patients or in C-IBS patients. Spasmolytic and laxative agent intakes were not different between the two groups. Subjective evaluation by patients of treatment efficacy and visual analogue scale test of treatment efficacy by investigators were significantly better in the beidellitic montmorillonite group (P < 0.05). Tolerance of beidellitic montmorillonite was considered optimal without any significant adverse event.

CONCLUSIONS

Although pain or discomfort was not significantly improved in the entire IBS population treated with beidellitic montmorillonite in comparison with placebo, this study demonstrates that beidellitic montmorillonite is efficient for C-IBS patients (P < 0.016). This effect of beidellitic montmorillonite on pain cannot be explained by changes in bowel habits. The efficacy of this well-tolerated therapy warrants further confirmatory therapeutic trials in C-IBS patients.

Clinicopathological features of pure mica pneumoconiosis associated with Sjögren syndrome

BACKGROUND

There are few reports on the clinical, radiologic, and pathologic features of pure mica pneumoconiosis.

METHODS

A case of definite pure mica pneumoconiosis in a rubber factory worker is reported with the clinicopathological findings.

RESULTS

Chest HRCT demonstrated subpleural and peribronchovascular interstitial thickening. The characteristic histologic features were pulmonary fibrosis accompanied by prominent histiocytic granulomas containing giant cells.

CONCLUSIONS

Pure mica pneumoconiosis can be identified by specific radiologic and pathologic findings.

Pneumoconiosis in Rush Mat Workers Exposed to Clay Dye “Sendo” Dust

STUDY OBJECTIVES

The purpose of this study was to describe the clinical, chest radiographic, high-resolution CT, and histopathologic features of clay dye "sendo" dust pneumoconiosis in seven rush mat ("tatami") workers.

PATIENTS

Seven patients with a history of occupational exposure to sendo dust and radiographic changes suggestive of pneumoconiosis were retrospectively reviewed.

RESULTS

The duration of exposure ranged from 15 to 45 years (median, 30 years). Three patients had cough, and four patients had abnormal pulmonary function test results. Chest radiographs showed nodular opacities < 3 mm in diameter (types p and q) in all patients. The standard International Labor Office profusion score ranged from 0/1 to 1/1 (median, 1/0). High-resolution CT demonstrated small nodular opacities (types p and q) in all seven patients. In four patients, high-resolution CT demonstrated branching centrilobular structures, airway ectasia, airway wall thickening, and emphysematous changes. None of the patients had conglomerate nodules, large opacities, honeycombing, pleural effusion, or lymphadenopathy. Microscopic examination of the specimens obtained by open lung biopsy or transbronchial lung biopsy revealed nodular fibrosis with accumulation of dust-laden macrophages, but no silicotic nodules. Needle-like particles of 1 to 20 microm in length were evident among the dust deposits, and birefringent crystals were identified under polarizing microscopy. Four of seven patients showed intra-alveolar fibroblastic foci similar to Masson bodies, accompanied by dust deposition.

CONCLUSION

Rush mat workers' sendo dust pneumoconiosis is caused by dust containing free silica. The radiographic and high-resolution CT findings consist of small nodular opacities < 3 mm in diameter and bronchial and bronchiolar abnormalities.

Use of natural and synthetic aluminosilicates in decontamination of feed contaminated by fungi and micotoxins

The contamination of feed with micotoxin has been a serious problem in animal nutrition. Many existing methods of decontamination are not satisfying due to the toxicological safety and health quality of the fodder materials. It stimulates the scientists to search for the new methods. The use of sorbents in the form of natural and synthetic aluminosilicates is a promising direction. The efficacy of aluminosilicates towards aflatoxins has been proved. However, their influence on other micotoxins is not that obvious. According to the last investigations, the use of aluminosilicates in nutrition does not cause any side effects and widespread pathological effects are observed only when dosage is incorrect. Regarding the analyses that were published, it can be supposed that the addition of several different aluminosilicates is a sufficient protection against mycotoxicoses.

In vivo effect of a resin-modified glass ionomer cement on enamel demineralization around orthodontic brackets

Because the risk of dental caries increases with the use of orthodontic appliances and its control cannot depend only on the patient's self-care, this study evaluated the effect of a glass ionomer cement on reducing enamel demineralization around orthodontic brackets. Fourteen orthodontic patients were randomly divided into 2 groups of 7; they received 23 brackets fitted to their premolars, bonded with either Concise (3M Dental Products, St Paul, Minn), a composite resin (control group), or Fuji Ortho LC (GC America, Chicago, Ill), a resin-modified glass ionomer cement (experimental group). The volunteers lived in a city that has fluoridated water, but they did not use fluoridated dentifrices during the study. After 30 days, the teeth were extracted and longitudinally sectioned; in the enamel around the brackets, demineralization was assessed by cross-sectional microhardness. The determinations were made at the bracket edge cementing limits, and at occlusal and cervical points 100 and 200 microm away from them. In all of these positions, indentations were made at depths from 10 to 90 microm from enamel surface. Analysis of variance showed statistically significant effects for position, material, depth, and their interactions (P<.05). The Tukey test showed that the glass ionomer cement was statistically more efficient than the control, reducing enamel demineralization in all analyses (P<.05). The use of glass ionomer cement for bonding can be encouraged because it decreases the development of caries around orthodontic brackets.

Pneumoconiosis in a vermiculite end-product user

BACKGROUND

Vermiculite is a silicate used as an insulating agent, soil additive, and carrier for chemicals and fertilizers. It is currently perceived to have no adverse effects to "end-product" users. An 82-year-old man presented with complaints of progressive dyspnea on exertion.

METHODS

A clinical evaluation included a chest radiograph, complete pulmonary function testing, CT scan of the thorax, and comprehensive occupational and environmental history.

RESULTS

The patient had clinical and radiographic features of advanced pulmonary interstitial fibrosis. The presence of calcified pleural plaques, together with the other clinical and radiographic features, strongly supported a diagnosis of asbestosis. His only significant exposure was to vermiculite used in the workplace for several hours per day from 1970 to 1987.

CONCLUSIONS

This case represents the first report of an end-product vermiculite-user with probable asbestosis, and together with recent similar findings in a vermiculite expansion plant worker, requires further epidemiologic investigations.

The effect of iron on the biological activities of erionite and mordenite

Epidemiological data has demonstrated that environmental and/or occupational exposure to mineral particulates may result in the development of pulmonary fibrosis, bronchogenic carcinoma and malignant mesothelioma many years following exposure. It has been suggested that the genotoxic effects of fibrous particulates, such as asbestos, is due in part to the generation of reactive oxygen species (ROS) from iron associated with the particulates. However, the molecular mechanisms by which mineral particulates induce ROS that results in genotoxic damage remains unclear. The naturally occurring zeolites, erionite and mordenite share several physiochemical properties but they elicit very different biological responses, with erionite, a fibrous particulate, being highly toxic, and mordenite, a nonfibrous particulate, being relatively benign. We are using these natural zeolites as a model system to determine what physicochemical properties of these zeolites are responsible for their biological response(s) and to evaluate the parameters that influence these responses. The purpose of the present study was to determine the mutagenic potential of erionite and mordenite and to determine whether this mutagenic potential was modulated by iron. The results of this study using the Chinese hamster ovary cell line AS52 demonstrated that erionite was more cytotoxic than mordenite. However, the cytotoxicity of both zeolites was increased in the presence of physiological concentrations of ferrous chloride. Ferrous ions (5-20 microM) significantly (p<0.001) increased the cytotoxicity of mordenite, but only at the highest concentration (16 microg/cm(2)) of mordenite tested. Conversely, only the highest concentration (20 microM) of ferrous ion significantly (p<0.001) increased the cytotoxicity of erionite, but this enhanced cytotoxicity occurred over a wider concentration range (6-16 microg/cm(2)) of erionite. Mordenite was not mutagenic at any of the concentrations tested, and the mutagenic potential of mordenite was not enhanced by the addition of ferrous ion. Conversely, erionite was mutagenic in a dose-response manner at concentrations greater than 6 microg/cm(2) and the mutagenic potential of erionite was significantly enhanced by the addition of ferrous ions. These results suggest that while the cytotoxicity of mordenite and erionite may be related to the ability of these fibers to transport iron into a cell, the different coordination state of iron associated with the two fiber surfaces is critical for inducing genotoxic damage.

Analysis of the biological and chemical reactivity of zeolite-based aluminosilicate fibers and particulates

Environmental and/or occupational exposure to minerals, metals, and fibers can cause lung diseases that may develop years after exposure to the agents. The presence of toxic fibers such as asbestos in the environment plus the continuing development of new mineral or vitreous fibers requires a better understanding of the specific physical and chemical features of fibers/particles responsible for bioactivity. Toward that goal, we have tested aluminosilicate zeolites to establish biological and chemical structure-function correlations. Zeolites have known crystal structure, are subject to experimental manipulation, and can be synthesized and controlled to produce particles of selected size and shape. Naturally occurring zeolites include forms whose biological activity is reported to range from highly pathogenic (erionite) to essentially benign (mordenite). Thus, we used naturally occurring erionite and mordenite as well as an extensively studied synthetic zeolite based on faujasite (zeolite Y). Bioactivity was evaluated using lung macrophages of rat origin (cell line NR8383). Our objective was to quantitatively determine the biological response upon interaction of the test particulates/fibers with lung macrophages and to evaluate the efficacy of surface iron on the zeolites to promote the Fenton reaction. The biological assessment included measurement of the reactive oxygen species by flow cytometry and chemiluminescence techniques upon phagocytosis of the minerals. The chemical assessment included measuring the hydroxyl radicals generated from hydrogen peroxide by iron bound to the zeolite particles and fibers (Fenton reaction). Chromatography as well as absorption spectroscopy were used to quantitate the hydroxyl radicals. We found that upon exposure to the same mass of a specific type of particulate, the oxidative burst increased with decreasing particle size, but remained relatively independent of zeolite composition. On the other hand, the Fenton reaction depended on the type of zeolite, suggesting that the surface structure of the zeolite plays an important role.

Fatal asbestosis 50 years after brief high intensity exposure in a vermiculite expansion plant

The authors report the case of a 65-year-old accountant whose only asbestos exposure was during a summer job 50 years earlier in a California vermiculite expansion plant. Vermiculite is a silicate material that is useful in building and agriculture as a filler and insulating agent. He developed extensive fibrocalcific pleural plaques and end-stage pulmonary fibrosis, with rapidly progressive respiratory failure. Careful occupational and environmental history revealed no other source of asbestos exposure, and the initial clinical diagnosis was idiopathic pulmonary fibrosis; open lung biopsy shortly before his death confirmed asbestosis. Electron microscopic lung fiber burden analysis revealed over 8,000,000 asbestos fibers per gram dry lung, 68% of which were tremolite asbestos. Additional asbestiform fibers of composition not matching any of the standard asbestos varieties were also present at over 5,000,000 fibers per gram dry lung. Comparison analysis of a sample of Libby, Montana, vermiculite showed a similar mix of asbestiform fibers including tremolite asbestos. This case analysis raises several concerns: risks of vermiculite induced disease among former workers of the more than 200 expansion plants throughout the United States; health effects of brief but very high-intensity exposures to asbestos; and possible health effects in end-users of consumer products containing vermiculite.

Mica dust as a cause of severe pneumoconiosis

BACKGROUND

Mica exposure is frequent in mines, mills, agriculture, construction, and industry. This is a case report of possible mica pneumoconiosis.

METHODS

Case report and description of pathology. Histology slides were subjected to spectroscopic examination.

RESULTS

Fibrosis in the presence of mica, without evidence of silica was confirmed.

CONCLUSIONS

This report indicates that mica exposure may result in mica pneumoconiosis.

Leakage associated with intermediate restorative material and glass-ionomer cement retrograde fillings: a human and sheep teeth comparison with 2 different aging procedures

OBJECTIVES

Leakage around retrograde fillings is an important cause of endodontic surgery. This in vitro study sought to compare the following: (1) methylene blue dye leakage linked to retrofillings in human and sheep teeth with the degree of dye penetration when intermediate restorative materials and Chemfil were used as retrofillings, (2) the apical microleakage in filled with that in unfilled root canals, and (3) 2 storage techniques, incubator-based and subcutaneous implantation in rats.

STUDY DESIGN

Tested were 198 human and 196 sheep teeth that were retrofilled with intermediate restorative material or Chemfil, then stored in an incubator or subcutaneously in rats for 10, 20, and 30 days before immersion in methylene blue dye for 24 hours. Linear dye penetration was evaluated, and the results were statistically analyzed by means of analysis of variance.

RESULTS

Leakage between sheep and human teeth was significantly different (P <.05). Chemfil had significantly less leakage than intermediate restorative material after storage in rat (P <.05) for up to 20 days, but not after 30 days. No differences were found between leakage of unfilled and filled human root canal teeth.

CONCLUSIONS

The sheep incisor is a poor experimental model of the human tooth, and both aging procedures demonstrate extensive leakage of retrofilling materials after long-term storage.

[Aspects of silicotuberculosis course in workers of highly aluminous mullite refractories]

The article covers differential diagnostic features of pulmonary tuberculosis and pneumoconiosis in workers engaged into mullite refractories production. The authors suggest that the disease courses as a new form of lung disorder--mullitosis.

Health hazards of ceramic artists

Ceramic artists can be exposed to many hazards including metals (such as lead), fibrogenic dusts (such as silica), heat, repetitive motion, radiation, and toxic emissions from kilns. The health risks of these exposures have not been well characterized among artists, although limited information is available from commercial potteries. Adverse health effects may be prevented by using less hazardous materials (such as lead-free glazes), improved ventilation, and proper work practices. Special precautions must be in place if children have access to the ceramics studio. The use of glazed ceramic dishes can be a risk for lead toxicity. Food should not be stored in glazed ceramics, and pregnant women should avoid daily use of ceramic mugs for drinking hot beverages.

Subacute fatal aluminum encephalopathy after reconstructive otoneurosurgery: a case report

We report a 52-year-old woman who underwent otoneurosurgery to resect acoustic neurinoma. Bone reconstruction was performed with an aluminium (Al)-containing cement. Six weeks later the patient suffered from loss of consciousness, myoclonic jerks, and persistent grand mal seizures, clinical symptoms that resembled those of lethal dialysis encephalopathy of the 1960s and 1970s. She died 6 months later because of septic complications. Light- and electron-microscopic investigation of the central nervous system (CNS) showed pathognomonic Al-containing intracytoplasmic argyrophilic inclusions in choroid plexus epithelia, neurons, and cortical glia. These changes are characteristics of dialysis-associated encephalopathy (DAE), induced nowadays by long-term ingestion of Al-containing drugs (and with benign clinical courses). Atomic absorption spectrometry showed an increase of mean bulk Al concentration of the cortex and subcortex up to 9.3 microg/g (normal range <2 microg/g); laser microprobe showed the increase of Al in subcellular structures. This unique case again shows the extraordinary neurotoxicity of Al, which was, in our patient, initiated by an amount of about 30 mg Al and apparently caused by direct Al access to the brain parenchyma via a cerebrospinal fluid leakage.

Ionomeric cement in the human middle ear cavity: long-term results of 23 cases

OBJECTIVES

The long-term results of the implantation of glass ionomer cement in the human mastoid and middle ear were studied.

STUDY DESIGN

A prospective study of the survival of bone cement in the middle ear.

METHODS

Ionocem (IONOS, Medizinische Produkte Gmbh & Co., Seefeld/Obb, Germany), a two-compound bone material that forms a stable, water-proof junction with bone, was implanted in 23 middle ears of 23 patients (13 male and 10 female patients). Closure of the dehiscence of the tegmen was performed in 7 cases, obliteration of the mastoid cavity in 10 cases, and ossicular chain reconstruction in 6 cases.

RESULTS

The follow-up period was 5.1 years. Complications attributable to operation were not seen, but adverse tissue reaction with severe middle ear infection and abundant otorrhea occurred in six cases after 12 months, requiring repeat operation. In three more cases, a spontaneous extrusion of the bone cement was seen after 4 years. The bone cement was totally extruded in nine cases. The mean survival time was 28 months.

CONCLUSIONS

The use of Ionocem for obliteration of the mastoid cavity or for the closure of dehiscence of the tegmen has a high risk of extrusion. Therefore, it is not the first-choice material to use for obliteration or tegmen defect closure in the middle ear.

Clay pica has no hematologic or metabolic correlate in chronic hemodialysis patients

OBJECTIVE

Clay pica is a form of compulsive ingestion of non-nutritive substances frequently practiced by dialysis patients. Its consequences are unknown. In this study, we evaluated the effect of regular consumption of clay on hematologic and metabolic profiles in hemodialysis patients.

DESIGN

A prospective, case-control study with use of structured questionnaire.

SETTING

Free-standing hemodialysis units.

PATIENTS

One hundred thirty-eight patients on hemodialysis for at least 12 months were interviewed. Thirteen of 138 (9.4%) confessed to clay pica. Ten randomly selected patients with no history of pica served as control.

INTERVENTION

Average of all laboratory profiles and interdialytic weight gain (IDWG) over a 3-month period were recorded. Assay of the aluminum (Al), silica (Si), and iron (Fe) content of commercially purchased clay was performed.

MAIN OUTCOME MEASURE

Comparison of laboratory profiles and IDWG between cases and control. Estimation of the daily consumption of Al, Fe, and Si from clay and their relationship to the laboratory profiles.

RESULTS

There was no statistically significant difference in the levels of Al, albumin, calcium, ferritin, hematocrit, iron saturation, phosphorus, and IDWG between pica cases and control. Iron was significantly higher in pica patients (13.0 +/- 7.9 micromol/L v 7.5 +/- 2.5 micromol/L, P =.04), but potassium was higher among control than pica cases (4.9 +/- 0.7 mmol/L v 4.4 +/- 0.6 mmol/L, P =.07). Estimated metal exposure from daily clay consumption per patient were: Al (1-2 mg), Fe (11-23.5 mg), and Si (2-4.5 g). Multivariate logistic regression analysis failed to show any association between clay consumption and nutrition, anemia, or mineral metabolism (R(2) = 0.0, P =.79).

CONCLUSION

Clay pica does not appear to be detrimental to the hematologic and metabolic milieu of hemodialysis patients. The practice should, however, be discouraged, because of potential for ingestion of unknown substances, and reported potential for gastrointestinal complications.

Enamel wear of modified porcelains

PURPOSE

To evaluate the wear of three different modified ceramics along with a conventional porcelain and the wear of opposing enamel at initial wear cycle on a two-body and a three-body wear simulation.

MATERIALS AND METHODS

Modified ceramics used in this study included a low fusing/low crystal porcelain (Finesse), a high fusing/low crystal porcelain (Softspar), and a heat-pressable ceramic (IPS Empress). A conventional porcelain (Ceramco II) was used as the control material. Hemispherical shaped ceramic styli (1/8 inch in diameter) made of respective materials were fabricated according to the manufacturers' directions. Proximal surfaces of non-carious human molars were ground flat within the enamel with a silicon carbide paper to 600 grit with copious irrigation. They were perpendicularly opposed to each other with or without intermediate material as a food bolus and subjected to in vitro wear test by a UAB wear simulator. A 75.6 N load was applied vertically onto the surface at 1.2 Hz. The surface was duplicated after respective wear cycles. Seven specimens were tested for each group of both simulations.

RESULTS

The enamel wear loss when opposing the modified ceramics was less than the Ceramco II control which exhibited the greatest values. The IPS Empress material showed the least amount of wear among them. Statistically significant differences were seen between the IPS Empress and the Ceramco II for every cycle interval evaluated (ANOVA, P < 0.05). Although the enamel wear loss when opposing the IPS Empress was significantly less (ANOVA, P < 0.05) than the others until 20,000 wear cycles, no significant differences were found among the modified ceramics at the end of 50,000 wear cycles. The concentric wear patterns were already prominent at 5,000 wear cycles on two-body wear, however, the wear facet of the three-body wear was smaller (the wear depth of 0-5 microm) than the two-body wear test, as it was quite similar to the one of the two-body wear test at 100 wear cycles. On the other hand, although no statistically significant differences were found among the three modified ceramics and between the conventional porcelain and the modified ceramics at every wear cycle, the high values of the Finesse since 10,000 wear cycles were probably due to the mechanical properties of this porcelain. Moreover, on the surface of the ceramic styli at the end of 50,000 wear cycles, the glaze layer on the contact area had not yet worn off.

Delayed-hypersensitivity granulomatous reaction induced by blepharopigmentation with aluminum-silicate

Blepharopigmentation has been introduced during the last decade as a technique for creating a permanent line along the eyelid margin, thus simulating a cosmetic eyeliner. Complications related to this procedure are mostly reported in the opthalmologic literature describing infectious, allergic, or technical problems. We report a case of a woman who underwent blepharopigmentation with aluminum-silicate and in whom a delayed hypersensitivity granulomatous reaction developed.

[Characteristics of work conditions in mullitic refractories production]

Specific feature of occupational medicine in highly aluminiferous mullitic refractories production nowadays is dust factor associated with disintegration, crushing and pressing of fireclays and coal clays. Therefore average shift dust levels increase and considerably exceed the MAC. Calcination process is associated with slightly exceeded MAC for sulphur dioxide and carbon dioxide and MAL for noise.

In vitro and in vivo tests for determination of the pathogenicity of quartz, diatomaceous earth, mordenite and clinoptilolite

The effects of samples of crystalline quartz, diatomaceous earth, mordenite and clinoptilolite were investigated in vitro (as concerns erythrocyte haemolysis and lactate dehydrogenase (LDH) release from peritoneal macrophages) and in vivo (on LDH, protein and phospholipids in rat bronchoalveolar lavage (BAL), and phospholipids in rat lung tissue). The respirable mineral samples were instilled intratracheally. Determinations in the BAL were carried out after 15, 60 and 180 days, and in the lung tissue after 90, 180 and 360 days. Quartz DQ and quartz FQ induced acute, subacute and chronic inflammation and progressive fibrosis. However, due to the Al2O3 contamination on the surface of the particles quartz FQ caused a delayed response in vivo. Diatomaceous earth produced acute/subacute inflammation that gradually became more moderate after 60 days. Clinoptilolite was inert, whereas the other zeolite sample, mordenite, was cytotoxic in vivo. The reason for this was presumably the needle and rod-shaped particles in the mordenite samples. The investigation revealed that different in vitro and in vivo methods canprovide valuable data concerning the pulmonary toxicity of minerals.

Clinical, pathological and mineralogical features in two autopsy cases of workers exposed to agalmatolite dust

An agalmatolite miner and processor showed large shadows at the bilateral hila accompanied by surrounding emphysematous changes and irregular shadows on chest X-ray films. Chest CT scans were characterized by a mixture of tiny irregular structures and small round opacities. Histopathological examination revealed massive fibrosis, which corresponded to large shadows, but only a small number of typical silicotic nodules, indicating mixed dust pneumoconiosis. Mineralogical examination of the autopsy lungs showed quartz, pyrophyllite, mica, and kaolinite. Quartz accounted for 70% of the amount of all mineral dust in both patients, but pyrophyllite accounted for 10.8% and 14.4%. The pulmonary mineral dust composition in the two patients was well consistent with the mineral composition of the raw clays in the agalmatolite mine. In the two patients, chest X-ray findings and histopathological findings of the lungs also suggested agalmatolite pneumoconiosis, which was confirmed by mineral analysis of the lungs.

Studies on the hazardous effects and the maximum allowable concentration of pyrophyllite dust

Pyrophyllite (H2Al2Si4O22) dust (P-dust) is a mixture of silica (10-40%), different proportions of a luminium oxide (Al2O3), and various metal compounds. People with occupations known to be associated with exposure to P-dust include miners, other industrial workers and persons engaged in artistic carving. Currently, little is known about pyrophyllite pneumoconiosis from P-dust. This study was designed to investigate the hazardous effects of P-dust and to suggest a maximum allowable concentration (MAC) of the dust. This study included four parts: (i) Occupational epidemiology survey in 781 workers from 1 pyrophyllite mine (PM) and four pyrophyllite carving mills (PCM), with a registration rate of 98%. (ii)

IN VITRO STUDIES

Six groups of rats were exposed to different levels of P-dust; the cytotoxicity of P-dust on rat alveolar macrophages (AM) was investigated by determining the potassium content of AM and the activity levels of lactate dehydrogenase (LDH) in AM culture fluid, (iii) Mineralogical analysis of P-dust: The contents of silica (SiO2), aluminum (Al), ferrum (Fe), nickel (Ni), zinc (Zn) and copper (Cu) in both PM-dust and PCM-dust were determined. (iv) Determination of P-dust MAC: Using the life-talbe method, an investigation of the hygiene standard of P-dust was carried out in 625 workers exposed to either PM-dust or PCM-dust, upon whom routine radiographs were performed. The results suggest that the risk of developing pneumoconiosis from pyrophyllite dust is significantly higher for PM workers than for PCM workers. The prevalence rate of PCM-dust pneumoconiosis is significantly higher in men than in women. The content of SiO2 and Al2O3 in the mixture of P-dust is the most important factor in the etiology of pyrophyllitosis. Depending on the different P-dust MAC values, we suggest that 2 mg/m3 and 4 mg/m3 should be considered as the MAC for PM-dust and PCM-dust, respectively, and 3 mg/m3 for P-dust. We believe that establishing different hygiene standards is more accurate even though workers are exposed to the "same" dust.

[Toxic aluminum encephalopathy. Predominant involvement of the limbic system on MRI]

Two patients underwent acoustic schwannoma surgery by transmastoid approach. Petrous bone defect was filled in with aluminium-containing bone cement (Ionocem). A pseudomeningocele by CSF accumulation in subcutaneous temporoparietal area appeared after the procedure and, in subsequent weeks, encephalopathy with confusion and seizures. MRI showed cerebral involvement with herpes-like disposition. Temporal stereotactic biopsy in a case did not confirm viral encephalitis but disclosed cellular accumulation of lipofucsin and particles highly suggestive of aluminum-inclusions. Aluminium's levels in blood and CSF of both patients were very high and confirm the brain's toxic involvement. Aluminium's toxicity would be advocated in patients with neurologic disorders who have undergone maxillofacial or skull bone-cementoplasty by an aluminum-containing biomaterial, if this cement is in contact with CSF.

In vitro biological effects of clay minerals advised as substitutes for asbestos

We studied one sample of commercial sepiolite and two samples of commercial vermiculite--clay minerals proposed as replacements for asbestos--and tested in vitro their abilities to activate complement, to lyse erythrocytes, and to elicit the production of reactive oxygen species (ROS) with human polymorphonuclear leukocytes (PMN) or bovine alveolar macrophages (AM); their behavior was compared with that of asbestos fibers obtained from the Union International Contra Cancer (UICC) as reference standards, as well as with kaolinite and illite, main members of the clay mineral family. Since in short-term in vitro tests the biological activity of mineral particles seems especially related to the active sites on their surface, we first measured the specific surface area of each mineral. Sepiolite was unreactive in two of the three tests we used (complement activation and ROS production) and able to lyse a minimal percentage of red blood cells. Vermiculite was shown to be incapable of activating complement, to have a moderate hemolytic activity and a high ability to elicite ROS production, although lower than that of chrysotile. Sepiolite, therefore, might be of more interest than vermiculite, given the low level of biological effects detected during the tests used to compare both clay minerals with asbestos fibres. The ROS production does not seem to require phagocytosis. A high ROS production was observed with kaolinite: this result casts doubt on the ability of pathogenic mineral dusts in vitro to induce a greater release of ROS than nonpathogenic mineral dusts.

Health effects of refractory ceramic fibres: scientific issues and policy considerations

OBJECTIVES

To review the scientific literature on the health effects of refractory ceramic fibres (RCFs). The adverse effects of exposure to asbestos has led to concern about the potential for other fibrous materials to cause diseases. For this reason the human populations most heavily exposed to synthetic mineral fibres have been examined for any adverse effects and many types of fibre have been studied in animal experiments. One type of man made vitreous fibres (MMVFs), refractory ceramic fibres (RCFs), are principally used in thermal insulation at high temperatures--up to 1400 degrees C. As manufactured RCFs exist in a glassy, non-crystalline (sometimes called amorphous) state, they have various compositions, physical properties, and sized fibres.

METHODS

All reports on the health effects of RCFs available up to the end of 1994 have been examined and the scientific literature reviewed although all publications have not necessarily been referenced.

CONCLUSIONS

In recent inhalation experiments conducted with both rats and hamsters at the Research and Consulting Company, Geneva, at the highest dose tested (30 mg/m3) there was an increased incidence of tumours in both species. Lower doses were only examined in the rat and at these doses there was no significant excess of lung tumours. Epidemiological investigations of workers engaged in the manufacture of ceramic fibres have shown a small excess of pleural plaques. This phenomenon is being further investigated but could be due to confounding exposures. The populations available for study are small and their exposures fairly short, but it is considered prudent that they should remain under surveillance for some time to come. This is despite the fact that present exposures in the ceramic fibre industry are low (< 1 f/ml) and are being reduced.

Vermiculite: a review of the mineralogy and health effects of vermiculite exploitation

Vermiculite is a mica-type mineral that is being used in increasing quantities for insulation, in composite cements, and in horticulture. No serious health risks have been found resulting from the exposure to vermiculite alone nor are any anticipated in view of its long-term chemical durability, even with respect to fibers of vermiculite. Vermiculite ores may contain a variety of other minerals including asbestos, which, if present in significant quantities, could pose a health risk to producers and end users. A variety of regulations are in place that should prevent inadvertent exposure to asbestos in vermiculites, but great care is needed if true asbestos hazards are to be correctly identified. At the same time, vermiculites containing any of a variety amphibole minerals should not be excluded from use because of mistaken identification of these minerals as asbestos. A variety of test methods that have been developed are described and recommendations are made with respect to appropriate action levels for asbestos in vermiculites or other raw materials.

Pharmacokinetic study of zeolite A, sodium aluminosilicate, magnesium silicate, and aluminum hydroxide in dogs

Zeolite A is a synthetic zeolite which may have therapeutic utility in osteoporotic individuals because of its ability to stimulate bone formation. A study of Zeolite A (30 mg/kg), sodium aluminosilicate (16 mg/kg), magnesium trisilicate (20 mg/kg), and aluminum hydroxide (675 mg) was designed in beagle dogs. The purpose of this study was to compare the oral bioavailability of silicon and aluminum from Zeolite A, sodium aluminosilicate, magnesium trisilicate, and aluminum hydroxide in dogs. Twelve female dogs received each compound as a single dose separated by one week in a randomized, 4-way, crossover design. Plasma samples were drawn at time 0 and for 24 hours after dosing. The concentrations of silicon and aluminum were determined by graphite furnace atomic absorption. The mean plasma silicon AUC values (+/- S.D.) were 9.5 +/- 4.5, 7.7 +/- 1.6, 8.8 +/- 3.0, 6.1 +/- 1.9 mg.hr/L and the mean plasma silicon Cmax values (+/- S.D.) were 1.07 +/- 1.06, 0.67 +/- 0.27, 0.75 +/- 0.31, 0.44 +/- 0.17 mg/L for Zeolite A, sodium aluminosilicate, magnesium trisilicate, and aluminum hydroxide respectively. Although mean silicon AUC and Cmax values were elevated when compared to baseline after administration of the silicon containing compounds, only the AUC from Zeolite A reached statistical significance (p = 0.041). The mean plasma silicon Tmax values (+/- S.D.) were 7.9 +/- 6.4, 5.8 +/- 4.6, 6.9 +/- 6.3 and 8.5 +/- 3.4 hrs for Zeolite A, sodium aluminosilicate, magnesium trisilicate and aluminum Hydroxide respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Analyses of the 1990 chest health survey of china clay workers

During 1990 all present and retired china clay workers in the United Kingdom were invited to take part in a chest health survey. A total of 4401 china clay workers participated representing over 70% of current employees and 17% of pensioners. The survey consisted of a chest x ray film, lung function measurements, and a questionnaire on respiratory symptoms and smoking habits. The chest x ray films were read by three readers to the International Labour Office (ILO) 1980 classification. Full details of occupational history for each participant were available and for each employee an estimate of total exposure to china clay dust was derived from representative dust concentrations for each location and job. These were based on measured dust concentrations after 1978 and on estimates before 1978. Analyses of the data were carried out to investigate the relations between exposure, x ray film category, lung function, and respiratory symptoms. The percentage of people with small opacities greater than major x ray film category 1 was 0.8% (lower than in previous studies). Dust concentrations have been reduced in recent years, averaging 1.7 mg m-3 for dryers in 1990 compared with 3.5 mg m-3 in 1978. The lower effect of exposure after 1971, compared with earlier exposure, was confirmed by the analyses. After 1971 the milling of dried china clay (Atritor mills) was found to be the occupation with the highest effect on x ray film category. The relation between total exposure to china clay dust and x ray film category is such that a typical non-smoker worker employed in the most dusty of current occupations may expect to reach the lower limit of category 1 after about 42 years continuous employment in that job at current exposures. Both forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were found (as in other studies) to decline with age, more rapidly for smokers than non-smokers at the rates for FVC of 0.035 l/y and 0.033 l/y, whereas for FEV1 the rates are 0.039 l/y for smokers and 0.034 l/y for non-smokers. Changes in x ray film category are also related to lung function , a change of one major category being equivalent to about six years of aging in its effect on FEV1.