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.