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

Abstract

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.

Chemical stability and dehydration behavior of a sepiolite/indigo Maya Blue pigment

“…The potential fixation in both palygorskite and sepiolite matrices of differently colored dyes may lead to the creation of a new category of pigments, with all possible hues. Studies in the medical field proved that the fibrous habit of these clays is not dangerous for human health (Governa et al, 1995). An absence of poisonous materials (heavymetals) and low production expenses would ensure, in addition, these pigments to be ecologically-oriented and cheap.…”

Wollastonite Fibersin VitroGenerate Reactive Oxygen Species Able to Lyse Erythrocytes and Activate the Complement Alternate Pathway

“…Cells, reactive mixtures, and sera were challenged with wollastonite and asbestos fibers. As in previous investigations (Governa et al, 1995(Governa et al, , 1997, we needed to normalize the doses of mineral particles with different physical characteristics and opted for the parameter of specific surface area, since ROS production is a function of the active sites present on these surfaces (Pezerat, 1991). By dosing the minerals on the basis of total surface area we believe that we have solved the problem Note.…”

Toxicological evaluation of clay minerals and derived nanocomposites: A review

“…Several researchers have studied the effects related with ROS generation and other disorders in several target cell lines exposed to different unmodified and modified clay minerals and derived micro/nanocomposites (Baek et al, 2012;Governa et al, 1995;Hansen and Mossman, 1987;Houtman et al, 2014;Kevadiya et al, 2013Kevadiya et al, , 2014Lordan et al, 2011;Maisanaba et al, 2013Maisanaba et al, , 2014aMeibian et al, 2010;Sharma et al, 2010) (Table 5).…”