Analysis for asbestos in environmental samples.

As we get into more and more analysis of environmental material, it is becoming increasingly apparent-in large part because of man's effect-that it is critical to take a look at composition as a function of size distribution of these small particles. The Duluth situation is one well known to this group, and I think it is an excellent example. It is one in which we have natural contributions of material from along the lake shore and sediments in the lake subject to the possibility of resuspension as well as various industrial and even municipal discharges into the lake. Now if you look at the size distribution as presented by Nicholson (1) and at the parameters other than amphiboles, you find that in the kind of material you would see at 1000 X, whether using electron microscopy or light microscopy, you get a tremendous amount of biological material. It is clear, as pointed out by Speil (2), that size fractions of materials that we are dealing with-here in terms of asbestos but also a broader range of minerals that are affected by industrial processes-are going to be very extensively skewed. Because of the problems we are facing at the moment, and our interest as researchers, the focus has been in terms of specific minerals or specific components. This has been clear throughout the whole history of pollution research. As we begin to take a look at the environmental concentrations of materials and get a better feeling for the kinds and variety of different compositions of inorganic and organic materials, we have to do a system study. I think that was very well pointed out by Speil's comments (2). The extent of Transite pipe used in the United States is such that we have a great deal of chrysotile available in water systems, both in supply and systems of waste discharge, that is clearly going to affect particle analyses in water and must be analyzed in our studies of natural water bodies. The geologist has often considered material found in water bodies as being from natural sources aside from obvious things like beer cans and great chunks of pollutants. He has considered these to be dominantly of natural origin, but I think as we work more on environmental samples of concern to man, we are going to have to take man's variety of discharges much more closely into consideration. We will have …