Irving J. Selikoff

THE OCCURRENCE OF ASBESTOSIS AMONG INSULATION WORKERS IN THE UNITED STATES

Information currently available concerning asbestosis has been derived largely from studies of employees of asbestos textile factories and should properly be referred to such individuals. I t is inadequate to speak now of “asbestos workers.” With the growth of asbestos utilization, including rapid multiplication of the number and variety of its applications, it would perhaps be more accurate to categorize workmen exposed to asbestos as “asbestos textile workers,” “asbestos insulation workers,” “asbestos miners,” “asbestos mill workers,” “asbestos-cement workers,” etc. The different occupations vary widely in important respects ; in intimacy, intensity and duration of exposure, in variety and grade of asbestos used, in working conditions, in concomitant exposure to other dusts or inhalants. The importance of this distinction and the parallel obligation to evaluate and study the experience of asbestos exposure in other trades, is emphasized by the fact tha t asbestos textile workers a re now a minority of those exposed during the industrial use of asbestos. There were good reasons for the early emphasis on asbestos textile workers. The first cases of asbestosis were in textile workers.’-’ Following the republication of Cooke’s case in 1927,’ with its rapid confirmation by the report of another case by Seiler,’ the Factory Department in Great Britain had to decide whether these were exceptional occurrences o r represented a significant health risk in industry. Accordingly, an investigation into the problem was undertaken during 1928 and 1929.“ The scope of the study had to be restricted. The textile industry was selected for study since only here was there pure or almost piire asbestos exposure. Since it was urgent t o investigate the effect of this dust, limiting the investigation to this branch of the industry avoided the possible complications which might be introduced by the presence of other potentially fibrogenic dusts. Moreover, in other asbestos trades, there were varying portions of asbestos in the dust to which workers were exposed, which would have added another complicating factor. I t was accepted that there were considerable numbers of workers exposed to mixed dusts whose r i sk would not be documented by study of the asbestos textile industry. Subsequent surveys, similarly designed to study the risk of industrial asbestos exposure, were also largely confined to asbestos textile works’ I’

RHEUMATOID FACTOR IN SERUM OF INDIVIDUALS EXPOSED TO ASBESTOS

I t is known tha t a factor ( o r factors) capable of reacting in various ways with gamma globulins may be found not only in the serum of persons affected by rheumatoid arthrit is , but also in patients with other diseases (particularly the so-called “collagen” diseases’ ) and even in apparently healthy individuals, with an increased frequency in older age.‘ I t is also known that these factors may differ in molecular size:’ or specificity, that is in their ability of reacting with rabbit o r human gamma globulins and even with human gamma globulins carrying different genetic markers.‘ I t appears, therefore, that the so-called “rheumatoid factors” or “rheumatoid-factor-like” substances may include a large family of reactors that a re induced by different conditions; the fact, however, that the rheumatoid factors always belong to the immunoglobulins ( IgG or, more often, IgM) and tha t they show a specificity of reactions comparable to those of antibodies, strengthens the concept that they arise as the consequence of an immunological stimulation. Various observations and experiments,-’.G support the possibility tha t the rheumatoid factors and related substances may be isoo r autoantibodies to gamma globulins; in the second instance the antigenic stimulation would be provided by autologous gamma globulins altered so to become autoantigens either by gross denaturation induced by some physical o r chemical agent or by more subtile changes in shape such a s those tha t accompany the formation of antigen-antibody complexe~.~ The latter possibility is very interesting because, if the modified gamma globulins of antigen-antibody complexes a re the stimulus for the production of rheumatoid-factor-like substances, we would have a good explanation for finding these substances in the course of many different diseases, which might have this in common: a prolonged period of immunological stimulation with sustained formation of antigen-antibody complexes “in vivo.” Chronic pulmonary diseases of various kind seem to be among those in which the presence of a rheumatoid factor in the serum a t good ti ters is B frequent finding. A positive reaction of the serologic tests for rheumatoid

THE DETECTION AND LOCALIZATION OF MINERAL FIBERS IN TISSUE

1 nt ~ o d uct ion A number of new techniques are described in this paper tha t make possible (1) the tagging of individual fibers with fluorochromes in vivo for a period of a t least one month and ( 2 ) facilitate the detection of otherwise “invisible” individual asbestos fibers and mineral particulates by electronic ashing of sections. These techniques were designed for use ( a ) in experimental studies in animals to locate individual fibers in s i t u shortly a f te r respiratory exposure and ( b ) in the study of human biopsy or autopsy specimens, especially in the absence of asbestos bodies. Localization by electronic ashing has proven highly satisfactory. Variations in procedure permit coi*relation of fiber location with histological structures. Studies of the effect of ashing on asbestos bodies a re also described. The advantages of the concomitant use of phase microscopy were demonstrated. The results of the fluorochromes experiments raise the question of mechanical fixation of particulate carcinogens in tissue, as well as the adsorption and concentration of dilute carcinogenic agents.

Lead exposure reduction in workers using stabilizers in PVC manufacture: effects of a new encapsulated stabilizer

The handling of lead-containing powdered stabilizers may be associated with excessive lead exposure and occupational lead poisoning. An encapsulated stabilizer has been designed, which is shown to result in a marked reduction in air lead levels and a concommitant decrease in blood lead concentrations in a group of blender operators manufacturing PVC electrical cable coating.

The Use of Immunological and Molecular Biological Techniques in the Assessment of Occupational and Environmental Disease

Environmental factors are playing an increasing etiologic role in the development of disease [1]. This includes both non-malignant and malignant illnesses. The occupational diseases do not differ biologically from other, non-occupationally-induced diseases, but are unique in their relation to the occupational-environmental conditions under which they have been induced. Recognition of risk to a certain population and the identification of causative environmental factors is, therefore, of profound importance; in fact, this forms the basis upon which the success of controlling environmental health hazards ultimately will depend.