magnesium-trisilicate and Neoplasms

Topics: Animals; Calcium Compounds; Carcinogens; Environmental Exposure; Humans; Magnesium Compounds; Magnesium Silicates; Neoplasms; Neoplasms, Experimental; Occupational Exposure; Silicates; Silicon Compounds; Zeolites

Produced worldwide at 1.2m tons per year, fibrous clays are used in the production of pet litter, animal feed stuff to roof parcels, construction and rheological additives, and other applications needing to replace long-fiber length asbestos. To the authors' knowledge, however, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the anti-inflammatory, anti-bacterial, and cytotoxic activity by sepiolite (Vallecas, Spain) and palygorskite (Torrejon El Rubio, Spain). The anti-inflammatory activity was determined using the 12-O-tetradecanoylphorbol-13-acetate (TPA) and myeloperoxidase (MPO) methods. Histological cuts were obtained for quantifying leukocytes found in the epidermis. Palygorkite and sepiolite caused edema inhibition and migration of neutrophils ca. 68.64 and 45.54%, and 80 and 65%, respectively. Fibrous clays yielded high rates of infiltration, explained by cleavage of polysomes and exposure of silanol groups. Also, fibrous clays showed high inhibition of myeloperoxidase contents shortly after exposure, but decreased sharply afterwards. In contrast, tubular clays caused an increasing inhibition of myeloperoxidase with time. Thus, clay structure restricted the kinetics and mechanism of myeloperoxidase inhibition. Fibrous clays were screened in vitro against human cancer cell lines. Cytotoxicity was determined using the protein-binding dye sulforhodamine B (SRB). Exposing cancer human cells to sepiolite or palygorskite showed growth inhibition varying with cell line. This study shows that fibrous clays served as an effective anti-inflammatory, limited by chemical transfer and cellular-level signals responding exclusively to an early exposure to clay, and cell viability decreasing significantly only after exposure to high concentrations of sepiolite.

Topics: Aluminum Silicates; Animals; Antacids; Anti-Bacterial Agents; Anti-Inflammatory Agents; Antidotes; Antineoplastic Agents; Cell Survival; Clay; Edema; Humans; Kinetics; Macrophages; Magnesium Compounds; Magnesium Silicates; Male; Mice; Neoplasms; Neutrophils; Peroxidase; Rats; Rats, Wistar; Silicon Compounds; Tetradecanoylphorbol Acetate

Attapulgite (palygorskite) and sepiolite are fibrous clay minerals used commercially as components in a wide variety of products including oil and grease adsorbents, carriers for pharmaceuticals, cosmetics, and pesticides. They are also components of drilling muds and animal litter and they are used as paint thickeners. The current annual worldwide production of these minerals exceeds one million tons. Although fibrous in nature, the fibre length may vary greatly depending on the location of the geological deposits. American attapulgite is short (0.1-2.5 micron in length, median of 0.4 micron) but palygorskite from other parts of the world is much longer (30% longer than 5 micron). Several samples of these materials have been submitted to scanning transmission electron microscopy (STEM). This paper reports the results of microscopic evaluations and makes a comparison with the data from experimental carcinogenicity studies and it is concluded that fibre length is a most important carcinogenic property.

Topics: Environmental Exposure; Humans; Magnesium; Magnesium Compounds; Magnesium Silicates; Microscopy, Electron, Scanning; Minerals; Neoplasms; Risk; Silicon; Silicon Compounds