Man made mineral fibers

Because the lungs are exposed to airborne hazardous materials, alveolar macrophages (AMs) play a major role in defending against the exposure to various noxious chemical substances. In this study, we reviewed magnetometric investigations of the effects of various chemicals on the lungs and AMs. Magnetometry, using magnetite as an indicator, was used to evaluate the effects of certain chemicals on the lung and AMs. A rapid decrease of the remanent magnetic field after the cessation of external magnetization, a phenomenon called relaxation, was impaired when the lungs and macrophages were exposed to toxic substances...

OBJECTIVES: The toxicity of microglass fibers (MG), one of the man-made mineral fibers, has not been sufficiently evaluated. The aim of the current study was to evaluate the cytotoxicity of MGin vitro. METHODS: Alveolar macrophages were obtained from the bronchoalveolar lavage of male F344/N rats. The macrophages were exposed to MG at concentrations of 0, 40, 80, 160 and 320 μg/ml. The effects of MG on the macrophages were examined by cell magnetometry, LDH assay and morphological observation...

No abstract text is available yet for this article.

OBJECTIVE: To examine the effects of exposure to occupational asbestos and man-made vitreous fibers (MMVF) across a wide range of occupations on risk of mesothelioma. METHODOLOGY: Two population-based case-control studies (1979-1986 and 1996-2001) provided 35 histologically confirmed mesothelioma cases and 1965 controls. A detailed job history was obtained to evaluate occupational exposure to many agents, including asbestos and MMVF. RESULTS: The mesothelioma odds ratio for exposure to any asbestos type was 3...

OBJECTIVE: To conduct a review and meta-analysis of risks of cancers of the lung and head and neck (HN) from exposure to rock wool (RW) and glass wool (GW). METHODS: We performed a systematic review and meta-analysis of risk estimates of lung and HN cancer in epidemiologic studies of workers exposed to man-made vitreous fibers (MMVF), specifically RW and GW. RESULTS: Sixteen estimates of lung cancer risk yielded a summary relative risk (RR) of 1...

Several sources of man-made vitreous fibers (MMVFs) may exist in an office environment causing irritation symptoms among occupants. In 258 office buildings, the occurrence and density of settled MMVFs on surfaces were measured by two sampling methods. Altogether, 1113 samples of settled dust were collected from surfaces with plastic bags and gelatine tape and were analyzed with a scanning electron microscope and a stereomicroscope, respectively. Tape samples from 68 buildings were collected from frequently cleaned (n = 162) and seldom cleaned (n = 57) room surfaces in 56 and 29 offices, respectively, and from supply air ducts (n = 24) in 10 offices...

Since fibrous particles such as asbestos and some man-made fibers (MMF) have been known to produce carcinogenic or fibrogenic effects, disk-shaped potassium octatitanate (POT) particles (trade name: Terracess TF) were manufactured as nonfibrous particles. A 90-day inhalation toxicity study of Terracess TF was performed to evaluate comparative inhalation toxicity of the disk shape with a fibrous shape that was previously evaluated. Four groups of 20 male and 15 female rats each were exposed to Terracess TF aerosols at concentrations of 0, 2, 10, or 50 mg/m(3) for 90 days...

No abstract text is available yet for this article.

No abstract text is available yet for this article.

OBJECTIVE: To examine the effects of occupational asbestos and man-made vitreous fibers (MMVF) on the risk of lung cancer in two population-based case-control studies entailing exposure at lower levels than in historic cohort studies. METHODOLOGY: Study I (1979 to 1986) comprised 857 cases and 1066 population and cancer controls. Study II (1996 to 2001) comprised 858 cases and 1295 population controls. A detailed job history was obtained to evaluate lifetime occupational exposure to 294 agents, including asbestos and MMVF...

Now among asbestos substitutes, the man-made organic fibers (MMOFs) find interesting applications on the industrial side. This class includes aramidic, polyacrylic, polyamides, polyolefins and polyvinylic fibers and it has been listed in category 3 of IARC classification (not classifiable as to carcinogenicity to humans). The aim of this study is to provide a panoramic regarding the toxicity of MMOFs present on the market according to their chemical-physical properties. Three materials have been taken in to consideration: the polyacrylonitrile (PAN), the polyvinyl alcohol (PVA) and the Kevlar...

To evaluate the safety of rock wool (RW), an asbestos substitute, we examined the biopersistence of RW fibers in rat lungs based on the changes of fiber number and fiber size (length and diameter) by a nose-only inhalation exposure study. Twenty-four male Fischer 344 rats were exposed to RW fibers at a concentration of 30 mg/m(3) continuously for 3 h daily for 5 consecutive days. Six rats each were sacrificed shortly and at 1, 2, and 4 wk after exposure, and their lung tissues were ashed by a low-temperature plasma asher...

A human monocytes cell line, U-937, incubated in the presence of filtered medium from Escherichia coli culture (FS) has been previously reported to degrade man made mineral fiber and it has been indicated as a good paradigm of in vivo fiber biopersistence evaluation (manuscript accepted for publication). In the present paper, a study is reported aimed to define the molecular modification occurring in the U-937 monocytes during in vitro fiber degradation. The induction of gene expression was investigated in U-937 exposed to rock wool fibers (HDN) in the presence of FS by transcriptome analysis using 20 K DNA microarrays and quantitative RT-PCR...

The toxicity of mineral fibers, whether they are natural or man made (MMMF), is usually evaluated in vivo using biopersistence tests in rodents. Development of an in vitro cellular model would be worthwhile in order to reduce, refine and finally replace animal models. For this purpose, we developed an in vitro assay using human monocytic cell line (U-937) to evaluate a new manufactured rock wool fiber (HDN) biodegradation. Experiments on earlier known mineral fibers asbestos (crocidolite) and glass wool fibers (CM44) were also performed...

The toxic effects of man-made mineral fibers (MMMFs) have been evaluated by cell magnetometry using alveolar macrophages (AMs). Recently, on the other hand, the murine macrophage cell line, RAW 264.7, became available and has been used as an in vitro model of AMs. The objective of this study was to determine whether or not cell magnetometry using RAW 264.7 cells can be used to evaluate the toxic effects of MMMFs. RAW 264.7 cells were exposed to one of the MMMFs, potassium octatitanate (PT) or silicon carbide whisker (SiC) at 0, 20, 40 and 60 microg/ml, or chrysotile as a positive control at 0, 15, 20 and 25 microg/ml...

We evaluated the pattern of pulmonary inflammation for the assessment of the biological hazards of two man-made mineral fibers. Rats were exposed by intratracheal instillation to a 2 mg dose of each of two kinds of man-made mineral fibers (PT1, potassium octatitanate whisker; and SiCW, silicon carbide whisker), or three kinds of comparable respirable particles (crystalline silica, crocidolite asbestos, and titanium dioxide, TiO(2)). The lung tissue was evaluated at 3 day, 1 wk, and 1, 3 and 6 mo after exposure...

Engineered nanoparticles (NP) comprise various classes of technological materials with innovative properties. Although inhalation is less likely for engineered nanomaterials (NM) compared with ambient or mineral dust particles, this can happen during bulk manufacture and handling of freely dispersible NP. In this mini-review we summarize recent data on NP and CNT (carbon nanotubes) hazards, with particular emphasis on toxic effect on lung and in cell culture of lung origin. Owing to the highest deposition efficiency in the alveolar area, primary interactions of NM occur with epithelial and alveolar macrophages (AM)...

Carbon nanotubes (CNT) and nanoparticles (NP) represent new classes of technological materials with innovative properties. Although inhalation is less likely for engineered nanomaterials (NM) compared with ambient or mineral dust particles, this can happen during bulk manufacture and handling of freely dispersable NP at workplace. Both environmental and engineered NP are able to cause oxidative stress, reactive oxygen species (ROS) generation, NF-kappaB activation, but some of the possible NM interactions with biological systems may result in additional forms of injury...

Glass wool or vitreous fibers are non-crystalline, fibrous inorganic substances (silicates) made primarily from rock, slag, glass, or other processed minerals. They belong to the man-made mineral fibers (MMMFs) group and their respiratory effects are well described by De Vuyst et al. [1995]. The authors pointed out the absence of firm evidence that exposure to these fibers is associated with lung fibrosis, pleural lesions, or non-specific respiratory disease in humans. Because of this observation, we find it of importance to present a case of interstitial fibrosis, which implies a direct association between long-term exposure to glass wool and the clinical outcome...

OBJECTIVES: To investigate the contribution of occupational exposure to asbestos and man-made vitreous fibres (MMVF) to lung cancer in high-risk populations in Europe. METHODS: A multicentre case-control study was conducted in six Central and Eastern European countries and the UK, during the period 1998-2002. Comprehensive occupational and sociodemographic information was collected from 2205 newly diagnosed male lung cancer cases and 2305 frequency matched controls...